Long-term outcome of primary clival chordomas: a single-center retrospective study with an emphasis on the timing of recurrences based on the primary treatment

OBJECTIVE

This study aimed to provide data on extended outcomes in primary clival chordomas, focusing on progression-free survival (PFS) and overall survival (OS).

METHODS

A retrospective single-center analysis was conducted on patients with clival chordoma treated between 1987 and 2022 using surgery, stereotactic radiosurgery, or proton radiation therapy (PRT).

RESULTS

The study included 100 patients (median age 44 years, 51% male). Surgery was performed using the endoscopic endonasal approach in 71 patients (71%). Gross-total resection (GTR) or near-total resection (NTR) was attained in 39 patients (39%). Postoperatively, new cranial nerve deficits occurred in 7%, CSF leak in 4%, and meningitis in none of the patients. Radiation therapy was performed in 79 patients (79%), with PRT in 50 patients (50%) as the primary treatment. During the median follow-up period of 73 (interquartile range [IQR] 38-132) months, 41 recurrences (41%) and 31 deaths (31%) were confirmed. Patients with GTR/NTR had a median PFS of 41 (IQR 24-70) months. Patients with subtotal resection or biopsy had a median PFS of 38 (IQR 16-97) months. The median PFS of patients who received radiation therapy was 43 (IQR 26-86) months, while that of patients who did not receive radiation therapy was 18 (IQR 5-62) months. The Kaplan-Meier method showed that patients with GTR/NTR (p = 0.007) and those who received radiation therapy (p < 0.001) had longer PFS than their counterparts. The PFS rates following primary treatment at 5, 10, 15, and 20 years were 51%, 25%, 17%, and 7%, respectively. The OS rates at the same intervals were 84%, 60%, 42%, and 34%, respectively. Multivariate Cox regression analysis showed that age < 44 years (p = 0.02), greater extent of resection (EOR; p = 0.03), and radiation therapy (p < 0.001) were associated with lower recurrence rates. Another multivariate analysis showed that age < 44 years (p = 0.01), greater EOR (p = 0.04), and freedom from recurrence (p = 0.02) were associated with lower mortality rates. Regarding pathology data, brachyury was positive in 98%, pan-cytokeratin in 93%, epithelial membrane antigen in 85%, and S100 in 74%. No immunohistochemical markers were associated with recurrence.

CONCLUSIONS

In this study, younger age, maximal safe resection, and radiation therapy were important factors for longer PFS in patients with primary clival chordomas. Preventing recurrences played a crucial role in achieving longer OS.

Correlation of older age with better progression-free survival despite less aggressive resection in nonfunctioning pituitary adenomas

OBJECTIVE

Nonfunctioning pituitary adenomas (NFPAs) present at a wide range of ages; it is possible that variable outcomes are based on patient age at presentation. This study aimed to explore long-term outcomes of patients with NFPAs following endonasal transsphenoidal surgery (ETS), considering age stratification.

METHODS

This retrospective study included 228 patients with NFPAs who underwent ETS, with a median follow-up period of 63 months. The outcomes included progression-free survival (PFS) rates and neurological and endocrinological outcomes. Age-stratified Kaplan-Meier and Cox proportional hazards analyses were performed. Patients were classified into four age groups: ≤ 49, 50-59, 60-69, and ≥ 70 years.

RESULTS

Age-stratified analysis showed a significant correlation between age and PFS in NFPAs (5-year PFS rates: 63.0% in those ≤ 49 years, 76.7% in those 50-59 years, 85.0% in those 60-69 years, and 88.1% in those ≥ 70 years; p = 0.001, log-rank test). Bivariate (HR 1.03, 95% CI 1.01-1.05; p = 0.001) and multivariable (HR 1.03, 95% CI 1.02-1.05; p = 0.001) analyses demonstrated that older age was significantly associated with longer PFS. Multivariable analysis also demonstrated that smaller maximum tumor diameter (HR 0.77, 95% CI 0.60-0.99; p = 0.036) and gross-total resection (HR 8.55, 95% CI 3.90-18.75; p = 0.001) were significantly associated with longer PFS. Multivariable logistic regression analysis demonstrated that only younger age was associated with postoperative improvement of male hypogonadism (HR 0.91, 95% CI 0.84-0.99; p = 0.019). Other postoperative neurological and endocrinological outcomes were not significantly associated with age.

CONCLUSIONS

Older patients with NFPAs treated with ETS demonstrated a longer PFS. Of endocrinological outcomes studied, only male hypogonadism improvement was associated with younger patient age.

Delayed vagal nerve compressive neuropathy following placement of vagal nerve stimulator: case report

Vagal neuropathy causing vocal fold palsy is an uncommon complication of vagal nerve stimulator (VNS) placement. It may be associated with intraoperative nerve injury or with device stimulation. Here we present the first case of delayed, compressive vagal neuropathy associated with VNS coil placement which presented with progressive hoarseness and vocal cord paralysis. Coil removal and vagal neurolysis was performed to relieve the compression. Larger 3 mm VNS coils were placed for continuation of therapy. Coils with a larger inner diameter should be employed where possible to prevent this complication. The frequency of VNS-associated vagal nerve compression may warrant further investigation.

Predicting the need for occipitocervical fusion for patients with lower clival chordoma: a single-center retrospective study

OBJECTIVE

To assess the impact of tumor extension into the occipital condyle (OC) in lower clival chordoma management and the need for occipito-cervical fusion (OCF).

METHODS

A retrospective analysis was conducted on 35 patients with lower clival chordoma. The preoperative area of the intact OCs, Hounsfield units, and the integrity of the apical ligament and the tectorial membrane were assessed using preoperative imaging.

RESULTS

Seven (20%) patients were in the OCF group. The OCF group exhibited a higher prevalence of preoperative pain in the neck or head (p = 0.006), ligament absence (p = 0.022), and increased propensity for postoperative wound issues (p = 0.022) than the non-OCF group. The OCF group had less intact OCs (p < 0.001) and higher spinal instability neoplastic score (p = 0.002) than the non-OCF group. All patients with intact OCs<60% underwent OCF, and those with OCs≥70% were treated without OCF. Those with OCs between 60% and 69% underwent OCF if the ligaments were eroded, and did not undergo OCF if the ligaments were intact. Treatment strategies varied, with endoscopic endonasal approach (EEA) alone being common. Radiation therapy was administered to 89% of patients. All three patients treated with OCF after tumor resection had wound issues; none treated with OCF before resection had wound issues. None developed atlanto-occipital instability. Survival rates did not significantly differ between groups.

CONCLUSIONS

In the absence of mobility-related neck pain, patients with lower clival chordoma and intact OC≥60%, intact apical ligament, and intact tectorial membrane, may not require OCF.

Unplanned returns to the operating room: a quality improvement methodology for the comparison of institutional outcomes to national benchmarks

OBJECTIVE

Unplanned returns to the operating room (RORs) constitute an important quality metric in surgical practice. In this study, the authors present a methodology to compare a department's unplanned ROR rates with national benchmarks in the context of large-scale quality of care surveillance.

METHODS

The authors identified unplanned RORs within 30 days from the initial surgery at their institution during the period 2014-2018 using an institutional documentation platform that facilitates the collection of reoperation information by providers in the clinical setting. They divided the procedures into 28 groups by Current Procedural Terminology and International Classification of Diseases, 9th and 10th Revision codes. They estimated national benchmarks of unplanned RORs for these procedure groups via querying the American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) registry during the period 2014-2018. Finally, they numerically assessed the unplanned ROR rates at their institution compared with those calculated from the ACS NSQIP registry.

RESULTS

Using the above methodology, the authors were able to classify 12,575 of the cases performed in their department during the period of interest, including 6037 (48%) cranial cases and 6538 (52%) spinal or peripheral nerve cases. Among those, 161 (1.3%) presented with complications that required an unplanned ROR within 30 days from the initial surgery. The respective cumulative unplanned ROR rate in the ACS NSQIP registry during the same timeframe was 3.6%. Among 15 categories of cranial procedures, the cumulative unplanned ROR rate was 1.3% in the authors' department and 5.6% in the ACS NSQIP registry. Among 13 categories of spinal and peripheral nerve procedures, the cumulative unplanned ROR rate was 1.3% in the authors' department and 2.8% in the ACS NSQIP registry. Unplanned ROR rates at the authors' institution were lower than the national average for each of the 28 procedure groups of interest. Yearly analysis of institutional ROR rates for the five most commonly performed procedures showed lower reoperation rates compared with the national benchmarks.

CONCLUSIONS

Using an institutional documentation tool and a widely available national database, the authors developed a reproducible and standardized method of comparing their department's outcomes with national benchmarks per procedure subgroup. This methodology accommodates longitudinal quality surveillance across the different subspecialties in a neurosurgical department and may illuminate potential shortcomings of care delivery in the future.

Extraocular muscle electromyographic recordings for intraoperative monitoring of cranial nerves III, IV, and VI: a single-center experience with intraorbital electrodes

OBJECTIVE

The objective of this study was to describe the quantitative features of intraoperative electromyographic recordings obtained from cranial nerve III, IV, and VI neuromonitoring using 25-mm intraorbital electrodes, in the larger context of demonstrating the practicality of this technique during neurosurgical cases.

METHODS

A 25-mm-long shaft-insulated intraorbital needle electrode is routinely used at the authors' institution for extraocular muscle (EOM) electromyographic monitoring of the inferior rectus, superior oblique, and/or lateral rectus muscles when their function is at risk. Cases monitored between January 1, 2021, and December 31, 2022, were reviewed for patient demographics, tumor location and pathology, EOMs monitored, pre- and postoperative examination, and complications from electrode placement. Compound muscle action potentials on triggered electromyography, as well as neurotonic discharges on free-run electromyography, were described quantitatively.

RESULTS

There were 141 cases in 139 patients reviewed during the 24-month time span, with 278 EOMs monitored (inferior rectus/superior oblique/lateral rectus muscles 68/68/142). Triggered electromyography yielded biphasic or triphasic compound muscle action potentials from EOMs with a mean onset latency of 1.51 msec (range 0.94-3.22 msec), mean maximal peak-to-trough amplitude of 1073.93 μV (range 76.75-7796.29 μV), and high specificity for the channel in nearly all cases. Neurotonic discharges were recorded in 30 of the 278 EOMs (with all 3 muscles represented) and associated with a greater incidence of new or worsened ophthalmoparesis (OR 4.62, 95% CI 1.3-16.4). There were 2 cases of small periorbital ecchymosis attributed to needle placement; additionally, 1 case of needle-related intraorbital hematoma occurred after the review period.

CONCLUSIONS

The 25-mm shaft-insulated intraorbital electrode facilitates robust and consistent electromyographic recordings of EOMs that are advantageous over existing techniques. Combined with the relative ease of needle placement and low rate of complications, the technique is practical for neuromonitoring during craniotomies.

Treatment modalities and outcomes of granular cell tumors and spindle cell oncocytomas of the pituitary gland: an analysis of two national cancer databases

BACKGROUND

Spindle cell oncocytomas (SCO) and granular cell tumors (GCT) are rare primary pituitary neoplasms; the optimal treatment paradigms for these lesions are unknown and largely unexplored. Thus, using national registries, we analyze the epidemiology, management patterns, and surgical outcomes of SCOs and GCTs.

METHODS

The National Cancer Database (NCDB; years 2003-2017) and the Surveillance, Epidemiology, and End Results Program (SEER; years 2004-2018) were queried for patients with pituitary SCOs or GCTs. Incidence, extent of surgical resection, and rate of postoperative radiation use for subtotally resected lesions comprised the primary outcomes of interest. All-cause mortality was also analyzed via time-to-event Kaplan-Meier curves.

RESULTS

SCOs and GCTs have an annual incidence of 0.017 and 0.023 per 1,000,000, respectively. They comprise 0.1% of the benign pituitary tumors registered in NCDB. A total of 112,241 benign pituitary tumors were identified in NCDB during the study period, of which 83 (0.07%) were SCOs and 59 (0.05%) were GCTs. Median age at diagnosis was 55 years, 44% were females, and median maximal tumor diameter at presentation was 2.1 cm. Gross total resection was achieved in 54% patients. Ten patients (7%) had postoperative radiation. Comparing patients with GCTs versus SCOs, the former were more likely to be younger at diagnosis (48.0 vs. 59.0, respectively; p < 0.01) and female (59% vs. 34%, p = 0.01). GCTs and SCOs did not differ in terms of size at diagnoses (median maximal diameter: 1.9 cm vs. 2.2 cm, respectively; p = 0.59) or gross total resection rates (62% vs. 49%, p = 0.32). After matching SCOs and GCTs with pituitary adenomas on age, sex, and tumor size, the former were less likely to undergo gross total resection (53% vs. 72%; p = 0.03). Patients with SCOs and GCTs had a shorter overall survival when compared to patients with pituitary adenomas (p < 0.01) and a higher rate of thirty-day mortality (3.1% vs 0.0%; p = 0.013).

CONCLUSION

SCOs and GCTs are rare pituitary tumors, and their management entails particular challenges. Gross total resection is often not possible, and adjuvant radiation might be employed following subtotal resection.

Acute to long-term characteristics of impedance recordings during neurostimulation in humans

Objective.This study aims to characterize the time course of impedance, a crucial electrophysiological property of brain tissue, in the human thalamus (THL), amygdala-hippocampus, and posterior hippocampus over an extended period.Approach.Impedance was periodically sampled every 5-15 min over several months in five subjects with drug-resistant epilepsy using an investigational neuromodulation device. Initially, we employed descriptive piecewise and continuous mathematical models to characterize the impedance response for approximately three weeks post-electrode implantation. We then explored the temporal dynamics of impedance during periods when electrical stimulation was temporarily halted, observing a monotonic increase (rebound) in impedance before it stabilized at a higher value. Lastly, we assessed the stability of amplitude and phase over the 24 h impedance cycle throughout the multi-month recording.Main results.Immediately post-implantation, the impedance decreased, reaching a minimum value in all brain regions within approximately two days, and then increased monotonically over about 14 d to a stable value. The models accounted for the variance in short-term impedance changes. Notably, the minimum impedance of the THL in the most epileptogenic hemisphere was significantly lower than in other regions. During the gaps in electrical stimulation, the impedance rebound decreased over time and stabilized around 200 days post-implant, likely indicative of the foreign body response and fibrous tissue encapsulation around the electrodes. The amplitude and phase of the 24 h impedance oscillation remained stable throughout the multi-month recording, with circadian variation in impedance dominating the long-term measures.Significance.Our findings illustrate the complex temporal dynamics of impedance in implanted electrodes and the impact of electrical stimulation. We discuss these dynamics in the context of the known biological foreign body response of the brain to implanted electrodes. The data suggest that the temporal dynamics of impedance are dependent on the anatomical location and tissue epileptogenicity. These insights may offer additional guidance for the delivery of therapeutic stimulation at various time points post-implantation for neuromodulation therapy.

Lower Cranial Nerve Schwannomas: Cohort Study and Systematic Review

BACKGROUND AND OBJECTIVES

Schwannomas originating from the lower cranial nerves (LCNS) are rare and pose a significant surgical challenge. Resection is the mainstay treatment; however, risk of treatment morbidity is considerable, and the available literature regarding differential treatment outcomes in this vulnerable population is sparse.

METHODS

A single-institution cohort study and systematic literature review of LCNS were performed.

RESULTS

Fifty-eight patients were included: 34 underwent surgical resection and 24 underwent stereotactic radiosurgery (SRS). The median age at diagnosis was 48 years (range 17-74). Presenting symptoms were dysphagia (63%), dysarthria/hypophonia (47%), imbalance (33%), and hearing loss/tinnitus (30%). Tumor size was associated with surgical resection, as compared with initial SRS (4.1 cm vs 1.5 cm, P = .0001). Gross total resection was obtained in 52%, with tumor remnants predominantly localized to the jugular foramen (62%). Post-treatment worsening of symptoms occurred in 68% of surgical and 29% of SRS patients ( P = .003). Postoperative symptoms were mostly commonly hypophonia/hoarseness (63%) and dysphagia (59%). Seven patients (29%) had new neurological issues after SRS treatment, but symptoms were overall milder. The median follow-up was 60 months (range 12-252); 98% demonstrated meaningful clinical improvement. Eighteen surgical patients (53%) underwent adjuvant radiation at a median of 5 months after resection (range 2-32). At follow-up, tumor control was 97% in the surgical cohort and 96% among SRS patients.

CONCLUSION

Although LCNS resection is potentially morbid, most postoperative deficits are transient, and patients achieve excellent tumor control-particularly when paired with adjuvant SRS. For minimally symptomatic patients undergoing surgical intervention, we advise maximally safe resection with intracapsular dissection to preserve nerve integrity where possible. For residual or as a primary treatment modality, SRS is associated with low morbidity and high rates of long-term tumor control.

Longitudinal treatment outcomes of recurrent clival chordomas: a single-center retrospective study

OBJECTIVE

The objective of this study was to clarify the detailed clinical course of recurrent clival chordoma and the outcomes of each treatment modality.

METHODS

A single-center retrospective analysis was conducted on patients seen for recurrent clival chordoma. The cohort was identified from those who underwent surgery, stereotactic radiosurgery, or proton therapy at the authors' institution between 1990 and 2022.

RESULTS

A total of 95 recurrences in 40 patients with a median (interquartile range [IQR]) follow-up of 43 (18-79) months were identified. The median (IQR) age at the time of diagnosis was 48 (36-62) years, and 55% of patients were male. Twenty-three patients were treated with surgery followed by adjuvant radiation before the first recurrence. The median (range) number of recurrences per patient was 2 (1-8), and the median (IQR) time to the first recurrence was 29 (9-51) months. The recurrences were treated with one or more of the following therapies: surgery, radiation, systemic therapy, and laser interstitial thermal therapy (LITT). Surgery was performed for 44 recurrences in 25 patients. Radiation was used to treat 42 recurrences in 28 patients. Patients with recurrences treated with surgery plus radiation had the longest progression-free survival (PFS) (median [95% CI] overall survival [OS] 120 [0-245] months, p < 0.01, log-rank test). Patients with recurrences but without prior radiation had longer PFS than those patients with prior radiation. The median (95% CI) OS after the first recurrence was 68 (54-82) months, 5-year OS after the first recurrence was 48%, and 10-year OS was 27%. Multivariate Cox regression analysis showed that mortality after the first recurrence was significantly associated with no adjuvant radiation (HR 0.149, 95% CI 0.038-0.59, p = 0.0067), older age at the time of the first recurrence (HR 1.04, 95% CI 1.01-1.08, p = 0.021), and total number of recurrences (p = 0.032). Seven patients received systemic therapy, and the median (95% CI) OS of these patients since initiation of systemic therapy was 31 (11-51) months. Imatinib and/or nivolumab were used in 6 patients (15%). One patient (3%) was treated with LITT for his fourth recurrence.

CONCLUSIONS

Despite the aggressive nature of recurrent chordoma, 14 of 29 patients (48%) survived for more than 5 years after the initial recurrence using combined therapies. Multiple treatment options may contribute to the long-term survival of patients with this intractable tumor.

The association of thromboembolic complications and the use of tranexamic acid during resection of intracranial meningiomas: systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

Antifibrinolytics, such as tranexamic acid (TXA), have been shown to decrease intraoperative blood loss across multiple surgical disciplines. However, they carry the theoretical risk of thromboembolic events secondary to induced hypercoagulability. Therefore, the aim of this study was to systematically review the available literature and perform a meta-analysis on the use of TXA in meningioma resection to assess thromboembolic risks.

METHODS

The PubMed, Web of Science, and Google Scholar databases were reviewed for all randomized controlled trials presenting primary data on TXA use during resection of intracranial meningiomas. Data were gathered on operative duration, venous thromboembolic complications, deep venous thrombosis, use of allogeneic blood transfusion, estimated blood loss (EBL), and postoperative hemoglobin. Patients who received TXA were compared with controls who did not receive TXA intraoperatively using random-effects models.

RESULTS

A total of 508 unique articles were identified, of which 493 underwent full-text review. Ultimately, 6 studies with 381 total patients (190 receiving TXA) were included in the final analysis. All 6 trials were randomized, blinded, and placebo controlled with a TXA administration rate of a 20-mg/kg load followed by a 1-mg/kg/hr infusion. All studies were performed in lower-middle-income countries. There were no reported instances of venous thromboembolism (VTE) in the TXA and non-TXA cohorts. Patients receiving TXA exhibited fewer allogeneic transfusions (21.5% vs 41.6% [OR 0.26, 95% CI 0.09-0.77], p = 0.02) and lower EBL (MD -282.48 mL [95% CI -367.77 to -197.20 mL], p < 0.001) compared with patients who did not receive TXA, and they also had lower rates of perioperative complications (10.7% vs 19.9% [OR 0.47, 95% CI 0.2-0.95], p = 0.04).

CONCLUSIONS

Current literature suggests that TXA is not associated with increased risk for VTE when administered during resection of intracranial meningioma. TXA appears to decrease intraoperative blood loss and allogeneic transfusion requirements during meningioma resection and thus may improve the safety of surgical management of this pathology.

Patterns of recurrence and disease progression in patients with positive-margin olfactory neuroblastoma following primary resection

OBJECTIVE

Olfactory neuroblastoma (ONB) is a rare, malignant tumor of the sinonasal tract that arises from olfactory epithelium. Although surgery is the preferred first-line treatment, tumor involvement of adjacent structures may preclude the ability to achieve negative margins during initial resection. Herein, the authors examine the oncological outcomes of patients with positive margins after primary resection of ONB, with the aim of determining predictors of disease progression and patterns of recurrence.

METHODS

The authors performed an institutional review of 25 patients with positive-margin ONB after resection. Cox survival analyses were used to determine any statistically significant predictors of worse progression-free survival (PFS) and overall survival (OS).

RESULTS

A total of 93 patients who were diagnosed with ONB were identified, of whom 25 patients had positive margins following their primary resection. Eleven (44%) had a delayed finding of positive margins that were initially negative in the operating room but returned as positive on final pathology. Four patients had subtotal resection (STR), whereas the remaining patients underwent gross-total resection. Twenty-four patients received adjuvant radiotherapy (96%), and 15 additionally received adjuvant chemotherapy (60%). Fourteen patients (56%) experienced recurrence/progression at a median time of 35 months following resection (IQR 19-70 months). Local recurrence occurred in 10 patients (40%), regional in 9 (36%), and distant metastasis in 2 (8%). In Cox survival analyses, the 5-year PFS and OS were 55.1% and 79.2%, respectively. Kadish stage D was predictive of worse PFS in univariate (hazard ratio [HR] 15.67, 95% CI 3.38-72.61, p < 0.001) and multivariate (HR 15.46, 95% CI 1.45-164.91, p = 0.023) analyses. Hyams grade, adjuvant chemotherapy, and primary radiotherapy were not associated with PFS. Furthermore, Kadish stage D and STR were predictive of worse OS in univariate analysis (HR 12.64, 95% CI 2.03-78.86, p = 0.007; HR 7.31, 95% CI 1.45-36.84, p = 0.016; respectively). However, local and regional recurrence was not associated with worse OS.

CONCLUSIONS

Approximately half of patients with positive-margin ONB may experience disease recurrence. Patients with an advanced disease stage (Kadish D) may have a higher likelihood of developing recurrence/progression. Furthermore, patients with tumor burden following resection (STR and Kadish D) may have worse OS. However, in positive-margin ONB with no gross disease following initial resection, the presence of disease recurrence does not significantly alter survival when receiving salvage therapy.

Thalamic stimulation induced changes in effective connectivity

Deep brain stimulation (DBS) is a viable treatment for a variety of neurological conditions, however, the mechanisms through which DBS modulates large-scale brain networks are unresolved. Clinical effects of DBS are observed over multiple timescales. In some conditions, such as Parkinson's disease and essential tremor, clinical improvement is observed within seconds. In many other conditions, such as epilepsy, central pain, dystonia, neuropsychiatric conditions or Tourette syndrome, the DBS related effects are believed to require neuroplasticity or reorganization and often take hours to months to observe. To optimize DBS parameters, it is therefore essential to develop electrophysiological biomarkers that characterize whether DBS settings are successfully engaging and modulating the network involved in the disease of interest. In this study, 10 individuals with drug resistant epilepsy undergoing intracranial stereotactic EEG including a thalamus electrode underwent a trial of repetitive thalamic stimulation. We evaluated thalamocortical effective connectivity using single pulse electrical stimulation, both at baseline and following a 145 Hz stimulation treatment trial. We found that when high frequency stimulation was delivered for >1.5 hours, the evoked potentials measured from remote regions were significantly reduced in amplitude and the degree of modulation was proportional to the strength of baseline connectivity. When stimulation was delivered for shorter time periods, results were more variable. These findings suggest that changes in effective connectivity in the network targeted with DBS accumulate over hours of DBS. Stimulation evoked potentials provide an electrophysiological biomarker that allows for efficient data-driven characterization of neuromodulation effects, which could enable new objective approaches for individualized DBS optimization.

A Novel Preoperative Score to Predict Long-Term Biochemical Remission in Patients with Growth-Hormone Secreting Pituitary Adenomas

OBJECTIVE

Transsphenoidal surgery (TSS) is considered the treatment of choice in most patients with growth hormone (GH)-secreting pituitary adenomas. Several preoperative factors have been studied to predict postsurgical remission. Our objective was to design a score that could be used in the preoperative setting to identify patients that will achieve long-term biochemical remission after TSS.

METHODS

A retrospective analysis of consecutive patients with GH-secreting pituitary adenomas that underwent TSS in our institution from 2000 to 2015 who fulfilled prespecified criteria were included. Logistic regression methods were used to evaluate independent preoperative variables predicting long-term remission. Beta coefficients were used to create a scoring system for clinical practice.

RESULTS

Sixty-eight patients were included, with a mean follow-up time of 87 months. Twenty (29%) patients had tumors with a Knosp grade ≥ 3A. Gross-total resection was achieved in 43 (63%) patients. Thirty-three (48%) patients had long-term biochemical remission after TSS. In a multivariate analysis, the following variables were statistically significantly associated with long-term biochemical remission: age, adenoma size (diameter), Knosp grade, GH level, and insulin growth-factor 1index 1 at diagnosis. A score of <3 out of 8 total points was identified as a cutoff associated with long-term remission, with a sensitivity of 91.4% and specificity of 72.7% (AUC 0.867, OR 28.44, 95% CI 6.94-116.47, P = < 0.001).

CONCLUSIONS

A novel, simple, easy-to-use scoring system was created to identify patients with the highest chances of long-term biochemical remission following TSS. This scale should be prospectively validated in a multicenter study before widespread adoption.

Inferior Petrosal Sinus Sampling Tumor Lateralization and the Surgical Treatment of Cushing Disease: A Meta-Analysis and Systematic Review

OBJECTIVE

To determine whether accurate inferior petrosal sinus sampling (IPSS) tumor lateralization is associated with improved clinical outcomes following the surgical treatment of Cushing disease.

METHODS

The presented study was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Data regarding patient demographics, IPSS tumor lateralization, and postoperative endocrinologic outcomes were abstracted and pooled with random effects meta-analysis models. Additional meta-regression models were used to examine the association between the accuracy of IPSS tumor lateralization and postoperative outcomes (recurrence/persistence or remission/cure). Statistical analyses were performed using the Comprehensive Meta-Analysis software (significance of P < 0.05).

RESULTS

Seventeen eligible articles were identified, yielding data on 461 patients. Within average follow-up duration (∼59 months), the rate of correct IPSS tumor lateralization was 69% [95% confidence interval: 61%, 76%], and the rate of postoperative remission/cure was 78% [67%, 86%]. Preoperative IPSS tumor lateralization was concordant with magnetic resonance imaging lateralization for 53% of patients [40%, 66%]. There was no significant association between the rate of correct IPSS tumor lateralization and postoperative remission/cure among study-level data (P = 0.735). Additionally, there was no association among subgroup analyses for studies using stimulatory agents during IPSS (corticotropin-releasing hormone or desmopressin, P = 0.635), nor among subgroup analyses for adult (P = 0.363) and pediatric (P = 0.931) patients.

CONCLUSIONS

Limited data suggest that the rate of correct IPSS tumor lateralization may not be positively associated with postoperative remission or cure in patients with Cushing disease. These findings bring into question the utility of IPSS tumor lateralization in the context of preoperative planning and surgical approach rather than confirming a pituitary source.

Acute to long-term characteristics of impedance recordings during neurostimulation in humans

Objective

This study aims to characterize the time course of impedance, a crucial electrophysiological property of brain tissue, in the human thalamus (THL), amygdala-hippocampus (AMG-HPC), and posterior hippocampus (post-HPC) over an extended period.

Approach

Impedance was periodically sampled every 5-15 minutes over several months in five subjects with drug-resistant epilepsy using an experimental neuromodulation device. Initially, we employed descriptive piecewise and continuous mathematical models to characterize the impedance response for approximately three weeks post-electrode implantation. We then explored the temporal dynamics of impedance during periods when electrical stimulation was temporarily halted, observing a monotonic increase (rebound) in impedance before it stabilized at a higher value. Lastly, we assessed the stability of amplitude and phase over the 24-hour impedance cycle throughout the multi-month recording.

Main results

Immediately post-implantation, the impedance decreased, reaching a minimum value in all brain regions within approximately two days, and then increased monotonically over about 14 days to a stable value. The models accounted for the variance in short-term impedance changes. Notably, the minimum impedance of the THL in the most epileptogenic hemisphere was significantly lower than in other regions. During the gaps in electrical stimulation, the impedance rebound decreased over time and stabilized around 200 days post-implant, likely indicative of the foreign body response and fibrous tissue encapsulation around the electrodes. The amplitude and phase of the 24-hour impedance oscillation remained stable throughout the multi-month recording, with circadian variation in impedance dominating the long-term measures.

Significance

Our findings illustrate the complex temporal dynamics of impedance in implanted electrodes and the impact of electrical stimulation. We discuss these dynamics in the context of the known biological foreign body response of the brain to implanted electrodes. The data suggest that the temporal dynamics of impedance are dependent on the anatomical location and tissue epileptogenicity. These insights may offer additional guidance for the delivery of therapeutic stimulation at various time points post-implantation for neuromodulation therapy.

Comparing Speech Recognition Outcomes Between Cochlear Implants and Auditory Brainstem Implants in Patients With NF2-Related Schwannomatosis

OBJECTIVE

To compare cochlear implant (CI) and auditory brainstem implant (ABI) performance in patients with NF2-related schwannomatosis (NF2).

STUDY DESIGN

Historical cohort.

SETTING

Tertiary academic center.

PATIENTS

A total of 58 devices among 48 patients were studied, including 27 ABIs implanted from 1997 to 2022 and 31 CIs implanted from 2003 to 2022. Three patients had bilateral ABIs, three had bilateral CIs, three had an ABI on one side and a CI on the other, one had a CI that was later replaced with an ipsilateral ABI, and one had an ABI and CI concurrently on the same side.

INTERVENTIONS

CI or ABI ipsilateral to vestibular schwannoma.

MAIN OUTCOME MEASURES

Open-set speech perception, consonant-nucleus-consonant word scores, and AzBio sentence in quiet scores.

RESULTS

Among all patients, 27 (47%) achieved open-set speech perception, with 35 (61%) daily users at a median of 24 months (interquartile range [IQR], 12-87 mo) after implantation. Comparing outcomes, CIs significantly outperformed ABIs; 24 (77%) CIs achieved open-set speech perception compared with 3 (12%) ABIs, with median consonant-nucleus-consonant and AzBio scores of 31% (IQR, 0-52%) and 57% (IQR, 5-83%), respectively, for CIs, compared with 0% (IQR, 0-0%) and 0% (IQR, 0-0%), respectively, for ABIs. Patients with ABIs were younger at diagnosis and at implantation, had larger tumors, and were more likely to have postoperative facial paresis.

CONCLUSION

Many patients with NF2-associated vestibular schwannoma achieved auditory benefit with either a CI or an ABI; however, outcomes were significantly better in those patients who were able to receive a CI. When disease and anatomy permit, hearing rehabilitation with a CI should be considered over an ABI in these patients. Tumor management strategies that increase the ability to successfully use CIs should be strongly considered given the high risk of losing bilateral functional acoustic hearing in this population.

Natural History of Serviceable Hearing During Active Surveillance of Nongrowing Sporadic Vestibular Schwannoma Supports Consideration of Initial Wait-and-Scan Management

OBJECTIVE

The treatment paradigm of vestibular schwannoma (VS) focuses on preservation of neurologic function, with small tumors increasingly managed with active surveillance. Often, tumor size and hearing outcomes are poorly correlated. The aim of the current work was to describe the natural history of hearing among patients with nongrowing VS during observational management.

STUDY DESIGN

Historical cohort study.

PATIENTS

Adults with sporadic VS.

INTERVENTION

Wait-and-scan management.

MAIN OUTCOME MEASURE

Maintenance of serviceable hearing (SH) after diagnosis.

RESULTS

Among 228 patients with nongrowing VS, 157 patients had SH at diagnosis. Rates of maintaining SH (95% CI; number still at risk) at 1, 3, and 5 years after diagnosis were 94% (89-98; 118), 81% (74-89; 65), and 78% (71-87; 42), respectively. Poorer hearing at diagnosis (hazard ratio [HR] per 10 dB hearing level increase in pure-tone average of 2.51, p < 0.001; HR per 10% decrease in word recognition score of 1.70, p = 0.001) was associated with increased likelihood of developing non-SH during observation. When controlling for baseline hearing status, tumors measuring 5 mm or greater in the internal auditory canal or with cerebellopontine angle extension were associated with significantly increased risk of developing non-SH (HR, 4.87; p = 0.03). At 5 years after diagnosis, 95% of patients with nongrowing intracanalicular VS measuring less than 5 mm maintained SH.

CONCLUSIONS

Hearing worsens during periods of nongrowth in sporadic VS. Patients with small (<5 mm) intracanalicular tumors demonstrate robust maintenance of SH over time, reinforcing the consideration of initial observation in this patient subset.

Extent of Surgical Resection as a Predictor of Tumor Progression in Skull Base Chordomas: A Multicenter Volumetric Analysis

INTRODUCTION

Skull-base chordomas are aggressive tumors with a propensity for recurrence/progression. Even with standard of care (SoC), 5-year recurrence rates are variable (19%-54%). This high recurrence/progression rate correlates with increased morbidity and mortality. We sought to analyze a multicenter cohort of skull base chordomas to identify predictors of progression in patients receiving SoC.

METHODS

The [Blinded]-Neurosurgery data registry was queried for skull base chordomas treated from 2008-2020. Patients with the histopathologic diagnosis of chordoma were included. The cohort was composed of patients with preoperative and postoperative magnetic resonance imaging. Tumor volume and radiologic characteristics were obtained from axial T2 sequences using a Digital Imaging and Communications in Medicine viewer. Survival analysis was performed using Kaplan-Meier method, and time-to-event multivariate regression was performed to identify independent predictors of progression.

RESULTS

The cohort included 195 patients, of which 66 patients met inclusion criteria; median age was 44, and 28 (42%) were females. Fifty-four (82%) received SoC, 7 (11%) resection only, and 5 (8%) radiotherapy only. Median preoperative and postoperative tumor volumes were 11.55 cm3 (0.33-54.89) and 0.34 cm3 (0-42.52), respectively. Recurrence rate with SoC was 37%. Postoperative tumor volume (P = 0.010) correlated with progression. A postoperative volume of >4.9 cm3 (P = 0.044), ≤81.3% of tumor resection (P = 0.02), and lower-clivus location (P < 0.005) correlated with decreased time to progression.

CONCLUSIONS

Skull base chordomas can be challenging to resect. Even though maximal resection and radiotherapy improve rate of tumor progression, many of these lesions eventually recur. We have identified a postoperative tumor volume of ≥4.9 cm3 and extent of resection of ≤81.3% in this cohort as predictors of progression in patients receiving SoC.

The clinical presentation of PIT1 positive pituitary neuroendocrine tumor immunonegative for growth hormone, prolactin, and thyroid stimulating hormone with analysis of clinical and immunostaining dissociation

BACKGROUND

PIT1 is a pituitary transcription factor that is associated with either growth hormone (GH), prolactin (PRL), or thyroid-stimulating hormone (TSH) production. However, PIT1-positive pituitary neuroendocrine tumors (PitNETs) are occasionally immunonegative for GH, PRL, and TSH. This paper describes the clinical presentation of PIT1 positive however immunonegative PitNETs.

METHODS

We conducted a retrospective analysis, identifying 228 PIT1-positive PitNET patients between 2017 and 2022. Out of these, ten (4%) tested negative for GH, PRL, and TSH. Functioning PitNETs were defined as those causing hormonal excess symptoms or hormonal overproduction.

RESULTS

As for 10 patients immunonegative for all three hormones however PIT1-positive, the mean ( ± standard deviation) age was 46 ± 13 years with 70% women. Six patients exhibited signs of excess GH or PRL, and three had visual problems. Additionally, one patient had secondary hypothyroidism and adrenal insufficiency resulting from the mass effect. All tumors were macroadenoma, with a median volume of 2.1 cm3 (range, 0.8-17.5 cm3). Gross total resection was attained in six patients by trans-sphenoidal surgery. Postoperatively, eight patients experienced clinical improvement: three in vision, two in amenorrhea, two in headache, and one in acromegaly symptoms. Biochemical improvement was observed in six patients, with all experiencing remission in hormonal excess and one showing improvement in secondary hypothyroidism. Stereotactic radiosurgery was performed in three patients.

CONCLUSIONS

Patients with functioning PitNETs may exhibit PIT1 staining without GH, PRL, or TSH staining. Hormonally active tumors exist in this patient population; therefore, close endocrine follow-up is necessary despite the lack of staining for GH, PRL, and TSH.

Temporo-Parietal Extraventricular Approach for Deep Brain Stimulation Targeting the Anterior Nucleus of the Thalamus: Institutional Experience

BACKGROUND AND OBJECTIVES

The anterior nucleus of the thalamus (ANT) is a common target for deep brain stimulation (DBS) for drug-resistant epilepsy (DRE). However, the surgical approach to the ANT remains challenging because of its unique anatomy. This study aims to summarize our experience with the posterior temporo-parietal extraventricular (TPEV) approach targeting the ANT for DBS in DRE.

METHODS

We performed a retrospective analysis of patients with DRE who underwent ANT-DBS using the TPEV approach between January 2011 and February 2021. Subjects with at least 6-month follow-up were eligible. The final lead position and number of active contacts targeting the anteroventral nucleus (AV) of the ANT were assessed using Lead-DBS. Mean seizure frequency reduction percentage and responder rate (≥50% decrease in seizure frequency) were determined.

RESULTS

Thirty-one patients (mean age: 32.9 years; 52% female patients) were included. The mean follow-up period was 27.6 months ± 13.9 (29, 16-36). The mean seizure frequency reduction percentage was 65% ± 26 (75, 50-82). Twenty-six of 31 participants (83%) were responders, P < .001. Two subjects (6%) were seizure-free for at least 6 months at the last evaluation. Antiepileptic drugs dose and/or number decreased in 17/31 subjects (55%). The success rate for placing at least 1 contact at AV was 87% (27/31 patients) bilaterally. The number of active contacts at the AV was significantly greater in the responder group, 3.1 ± 1.3 (3, 2-4) vs 1.8 ± 1.1 (2, 1-2.5); P = .041 with a positive correlation between the number of active contacts and seizure reduction percentage; r = 0.445, R 2 = 0.198, P = .012.

CONCLUSION

The TPEV trajectory is a safe and effective approach to target the ANT for DBS. Future studies are needed to compare the clinical outcomes and target accuracy with the standard approaches.

Anatomic Variants in the Anterior Inferior Cerebellar Artery Encountered During Resection of Vestibular Schwannomas

BACKGROUND AND OBJECTIVES

Vestibular schwannomas (VS) are often phenotypically benign lesions that may be technically challenging to resect because of involvement of neurovascular structures. The anterior inferior cerebellar artery (AICA) is commonly identified near VS, with variable position in relation to the tumor; however, little published literature describes anatomic and pathologic variants of AICA observed during VS resection.

METHODS

A prospectively maintained cohort of surgically managed VS with available operative reports and clinical/radiographic follow-up was queried and reviewed for noted aberrations.

RESULTS

We identified 66 cases with noted AICA abnormalities among 880 reviewer cases, including 20 loops extending into the internal auditory canal (2.3%), 18 arteries embedded in dura (2.0%), 15 AICA branches directly within VS (1.7%), 8 main trunk arteries coursing between cranial nerves 7 and 8 (0.9%), 3 arteries embedded in temporal bone (0.2%), 1 aneurysm (0.1%), and 1 artery bifurcating cranial nerve 6 (0.1%). The median age of AICA-variant patients was 55 years (range 19-74), and 29 were female (45%). Compared with the other AICA variants, tumors embedded with AICA tended to be larger lesions on maximal axial diameter (2.9 vs 1.6 cm; P = .006), they more commonly underwent less than total resection (73% vs 28%; P = .0001), and they had higher rates postoperative House-Brackmann scores >2 (47% vs 20%; P = .005). Two patients had radiographic and symptomatic postoperative cerebral ischemia or hemorrhage-1 from a bone-encased AICA and 1 from a dural embedded variant.

CONCLUSION

Anatomic variants of AICA occur in approximately 7% of VS operations. Most aberrations do not affect surgical or clinical outcomes, and the rate of major vascular injury was low. However, certain types variably add operative time and in the case of AICA encasement in the tumor, likely indicate a more aggressive tumor phenotype with lower rates of gross total resection and high incidences of facial nerve weakness.

Stereotactic Radiosurgery Outcomes in Medically and Surgically Failed or Nonsurgical Candidates with Medically Failed Prolactinomas: A Systematic Review and Meta-Analysis

Objective  Prolactinomas are treated with dopamine agonists (DAs) as first-line therapy and transsphenoidal surgery as an alternative approach for medically failed tumors. We sought to summarize the efficacy of stereotactic radiosurgery (SRS) in the medically and surgically failed prolactinomas as well as in nonsurgical candidates with medically failed prolactinomas by systematic review and meta-analysis. Method  A literature search was conducted according to the Preferred Reporting Items for Systematic Review and Meta-Analyses guideline. Results  A total of 11 articles (total N  = 709) met inclusion criteria. Thirty-three percent of patients were able to achieve endocrine remission at a mean follow-up of 54.2 ± 42.2 months with no association between stopping DA and endocrine remission. Sixty-two percent of patients were able to achieve endocrine control with DA therapy and 34% of patients were able to decrease the dose of DA dose when compared with pre-SRS DA dose at the end of the follow-up period. However, 54% of patients required DA at the end of the follow-up to control hyperprolactinemia. Ninety percent of patients were able to achieve radiologic control at the end of the follow-up in comparison to pre-SRS imagings. Furthermore, 26% of patients newly developed hypopituitarism (one or more pituitary hormones) post-SRS throughout the follow-up period. Conclusion  This systematic review and meta-analysis demonstrates SRS as an effective adjunct therapy in medically failed nonsurgical candidates or surgically and medically recalcitrant prolactinomas with a 33% chance of achieving endocrine remission, 62% of patients achieved hormonal control with DA and GKRS (gamma knife radio-surgery), with a 34% chance of decreasing DA dose and 90% chance of achieving radiologic control.

Rationale for the Development of a Novel Clinical Grading Scale for Postoperative Facial Nerve Function: Results of a Multidisciplinary International Working Group

OBJECTIVE

The objective of the current study was to present the results of an international working group survey identifying perceived limitations of existing facial nerve grading scales to inform the development of a novel grading scale for assessing early postoperative facial paralysis that incorporates regional scoring and is anchored in recovery prognosis and risk of associated complications.

STUDY DESIGN

Survey.

SETTING

A working group of 48 multidisciplinary clinicians with expertise in skull base, cerebellopontine angle, temporal bone, or parotid gland surgery.

RESULTS

House-Brackmann grade is the most widely used system to assess facial nerve function among working group members (81%), although more than half (54%) agreed that the system they currently use does not adequately estimate the risk of associated complications, such as corneal injury, and confidence in interrater and intrarater reliability is generally low. Simplicity was ranked as the most important attribute of a novel postoperative facial nerve grading system to increase the likelihood of adoption, followed by reliability and accuracy. There was widespread consensus (91%) that the eye is the most critical facial region to focus on in the early postoperative setting.

CONCLUSIONS

Members were invited to submit proposed grading systems in alignment with the objectives of the working group for subsequent validation. From these data, we plan to develop a simple, clinically anchored, and reproducible staging system with regional scoring for assessing early postoperative facial nerve function after surgery of the skull base, cerebellopontine angle, temporal bone, or parotid gland.

Immunohistochemical markers predicting recurrence following resection and radiotherapy in chordoma patients: insights from a multicenter study [RETRACTED]

OBJECTIVE

Chordomas are rare tumors that often recur regardless of surgery with negative margins and postoperative radiotherapy. The predictive accuracy of widely used immunohistochemical (IHC) markers in addressing the recurrence of skull base chordomas (SBCs) is yet to be determined. This study aimed to investigate IHC markers in the prediction of recurrence after SBC resection with adjuvant radiation therapy.

METHODS

The authors reviewed the records of patients who had treatment for SBC between January 2017 and June 2021 across the Mayo Clinic in Minnesota, Florida, and Arizona. Exclusion criteria included patients who had no histopathology or recurrence as an outcome. Histopathological markers included cytokeratin A1/A3 only, epithelial membrane antigen (EMA), S100 protein, pan-cytokeratin, IN1, GATA3, CAM5.2, OSCAR, and chondroid. Information from patient records was abstracted, including treatment, clinical and radiological follow-up duration, demographics, and histopathological factors. Decision tree and random forest classifiers were trained and tested to predict the recurrence based on unseen data using an 80/20 split.

RESULTS

A total of 38 patients with a diagnosis of SBC who underwent resection (gross-total resection: 42.1%; and subtotal resection: 57.9%) and radiation therapy were extracted from the medical records. The mean patient age was 48.2 (SD 19.6) years; most patients were male (n = 23; 60.5%) and White (n = 36; 94.7%). Pan-cytokeratin was associated with an increased risk of postoperative recurrence (OR 14.67, 95% CI 2.44-88.13; p = 0.00517) after resection and adjuvant radiotherapy. The decision tree analysis found pan-cytokeratin-positive tumors to have a 78% chance of being classified as a recurrence, with an accuracy of 75%. The distribution of minimal depth in the prediction of postoperative recurrence indicates that the most important variables were pan-cytokeratin, followed by cytokeratin A1/A3 and EMA.

CONCLUSIONS

The authors' machine learning algorithm identified pan-cytokeratin as the largest contributor to recurrence among other IHC markers after SBC resection. Machine learning may facilitate the prediction of outcomes in rare tumors, such as chordomas.

Assessing the Impact of Shifting Enfolded Neurosurgery Fellowships to Follow the Chief Resident Experience: National Survey of Program and Fellowship Directors

OBJECTIVE

The neurosurgery chief resident year is traditionally completed during the final residency year; however, a recent directive decried that enfolded fellowships should be undertaken following completion of the chief experience for most fellowships.

METHODS

A national survey was distributed to U.S.-based neurosurgery residency/fellowship directors regarding these changes.

RESULTS

We received 135 completed surveys (37% response rate). Respondents tended to feel the new post-chief enfolded fellowship mandate represented positive effects on residency training (58%) and chief experiences (54%)-overall, 47% agreed the changes are net positive, 17% neutral, and 36% negative. In addition, 66% respondents thought the enfolded fellowship was enhanced due to previous completion of the chief year. Most did not feel the directives had a negative impact on resident case minimums completion, total case volumes, or overall case mix during residency; but 64% felt it would reduce post-graduate training. Of those who said the mandate would reduce post-graduate training, 45% thought this would be positive. Throughout all questions, most respondents tended to feel strongly, although with little overall consensus across many of these questions. One area of relative agreement was a 60% preference to allow program discretion for chief/enfolded fellowship training timing-with 41% strongly supporting versus 15% strongly rejecting reversion to program-directed administration.

CONCLUSIONS

Fervent bimodal opinions exist among residency program and fellowship directors regarding the directives for enfolded fellowships to follow successful completion of the chief resident experience. However, there was broad support for allowing greater program discretion for directing certain enfolded fellowship timing and structure.

Implications of intracranial hemorrhage associated with stereo-EEG

OBJECTIVE

Intracranial hemorrhage (ICH) is a known complication during stereo-electroencephalography (sEEG) however true rates remain unknown. We provide a comprehensive review of ICH during sEEG regardless of clinical symptoms. Secondly, we analyzed sEEG recordings to identify electrographic correlates of ICH.

METHODS

This is a retrospective study of patients undergoing sEEG between January 2016 and April 2022 at the Mayo Clinic in Rochester. We reviewed medical records and imaging studies to identify ICH. We analyzed ICH by type, electrode trajectories, timing, sEEG findings and outcomes.

RESULTS

There were a total of 201 sEEG implants, of which 23 (11%) cases or 0.9% electrodes implanted had evidence of ICH. The majority of affected patients (82%) were either asymptomatic or had mild clinical neurological manifestations. In 90% of patients who proceeded with surgical treatments, outcomes were favorable. The most common sEEG finding in contacts in proximity of ICH was either focal slowing with interictal discharges or focal electrographic seizures.

CONCLUSIONS

ICH associated with sEEG is likely under-reported in literature. We present electroencephalographic correlates of ICH that may aid identification of ICH in the course of performing sEEG monitoring.

SIGNIFICANCE

Our data provides clinically relevant information on potential risks and outcomes of ICH. Furthermore, our findings aid identification of ICH during sEEG.

Staged Intracranial Free Tissue Transfer and Cranioplasty for a Refractory Nasal-cranial Base Fistula

After a transnasal endoscopic resection of a high-grade adenoid cystic carcinoma that underwent adjuvant chemoradiation, there was delayed recurrence managed by en bloc resection through an open craniofacial approach. Subsequently, the patient developed a chronic nasocranial fistula with secondary infection and bone flap resorption. This resulted in infectious episodes with secondary scalp incisional dehiscence and hardware exposure which required multiple bone debridement procedures, hardware removal, prolonged IV antibiotics, and hyperbaric oxygen treatment. The nasocranial fistula and chronic frontal bone osteomyelitis persisted despite the previous interventions. The patient underwent a frontal bone removal and obliteration of the anterior cranial base fistula with a free vastus lateralis muscle flap. At 4 weeks postoperatively, the intranasal portion of the muscle flap had completely mucosalized. After a 6-week course of IV antibiotics, a secondary cranioplasty using a custom-made poly-ether-ether-ketone implant was performed. The patient remained disease- and infection-free for the duration of follow-up (17 months).

Drug-resistant temporal lobe epilepsy with temporal encephaloceles: How far to resect

PURPOSE

This study sought to evaluate the impact of surgical extent on seizure outcome in drug-resistant temporal lobe epilepsy (DR-TLE) with temporal encephaloceles (TE).

METHODS

This was a single-institution retrospective study of patients who underwent surgery for DR-TLE with TE between January 2008 and December 2020. The impact of surgical extent on seizure outcome was evaluated. In a subset with dominant DR-TLE, the impact of surgical extent on neuropsychometric outcome was evaluated.

RESULTS

Thirty-four patients were identified (female, 56%; median age at surgery, 43 years). TE were frequently overlooked on initial magnetic resonance imaging (MRI), with encephaloceles only detected after repeat or expert re-review of MRI, additional multi-modal imaging, or intra-operatively in 31 (91%). Sixteen (47%) underwent limited resections, including encephalocele resection only (n = 5) and encephalocele resection with more extensive temporal corticectomy sparing the amygdala and hippocampus (n = 11). The remainder (n = 18, 53%) underwent standard anterior temporal lobectomy and amygdalohippocampectomy (ATLAH). Limited resection was performed more frequently on the left (12/17 vs. 4/17, p = 0.015). Twenty-seven patients (79%) had a favourable outcome (Engel I/II), and 17 (50%) were seizure-free at the last follow-up (median seizure-free survival of 27.3 months). There was no statistically significant difference in seizure-free outcomes between limited resection and ATLAH. In dominant DR-TLE, verbal memory decline was more likely after ATLAH than limited resection (3/4 vs. 0/9, p = 0.014).

CONCLUSION

Expert re-review of imaging and multi-modal advanced imaging improved TE identification. There was no statistical difference in seizure-free outcomes based on surgical extent. Preservation of verbal memory supports limited resection in dominant temporal cases.

Meningioma: A Biography-Tumor Forever Tied to the Origins and "Soul of Neurosurgery"

Meningiomas are neoplasms derived from the arachnoid cap cells of the leptomeninges and are the most common intracranial tumor. In the present historical vignette, the evolution of the management and diagnosis of meningioma is described. We begin with studies of skulls from the prehistoric record, such as the Steinheim skull, which demonstrate morphologic changes (e.g., hyperostosis) now known to occur with meningioma growth. We then continue with the earliest formal descriptions of meningiomas, including that by Platter, who published the first report of meningioma, along with early histopathologic descriptions by Cushing, who divined the cytological origins of the tumor and was the first to use the term meningioma. We conclude with a description of current management of meningiomas and potential avenues for further discovery. This article is effectively a lifetime biography of a tumor known and loved by neurosurgeons, the simple and yet complex meningioma.

Radiographic predictors of occult intracranial involvement in olfactory neuroblastoma patients

BACKGROUND

Traditional management of olfactory neuroblastoma (ONB) includes margin-negative resection with removal of cribriform plate, dura, and olfactory bulb, regardless of intracranial disease. This approach may be overtreating certain patients. Our investigation examines risk factors associated with occult intracranial disease to optimize therapeutic outcomes.

METHODS

This retrospective, multi-institutional cohort study examined clinical covariates associated with occult intracranial involvement. Patient demographics, staging, Hyam's grade, and pathologic involvement of dura, olfactory bulb/tract, and brain were collected. Diagnostic imaging was reviewed. Positive and negative predictive value (NPV) were estimated along with effect size estimates. Cox hazard regression examined associations with overall survival (OS) and disease-free survival (DFS).

RESULTS

A total of 224 subjects with new diagnoses of ONB (2005-2021) were identified. Skull base bone involvement on computed tomography (CT) had the highest NPV for pathologic dura (88.0%), olfactory bulb (88%), and brain involvement (97.3%). Hyam's grade category was significantly associated with dural involvement (φC  = 0.26; 95% confidence interval [CI]: 0.16, 0.42). Subjects without radiologic skull base involvement (n = 66) had pathologic positivity of 12.1%. Within this subgroup, Hyam's grade was clinically significant for dural positivity (φ = 0.34; 95% CI: -0.12, 0.71) with 28.6% involvement in high grade tumors. Neither clinical nor pathologic positivity of intracranial structures were associated with significantly different OS or DFS.

CONCLUSIONS

Both CT and magnetic resonance imaging (MRI) had reasonably good NPV for involvement of dura and olfactory bulb. Higher Hyam's grade was associated with dural involvement. Patients with low-grade tumors not involving the skull base may be suitable for avoiding skull base resection; however, further investigation is warranted.

Intraoperative diagnosis of facial schwannomas: a multicenter summation of clinical experience, preoperative avoidance, and intraoperative management protocol

OBJECTIVE

Preoperative differentiation of facial nerve schwannoma (FNS) from vestibular schwannoma (VS) can be challenging, and failure to differentiate between these two pathologies can result in potentially avoidable facial nerve injury. This study presents the combined experience of two high-volume centers in the management of intraoperatively diagnosed FNSs. The authors highlight clinical and imaging features that can distinguish FNS from VS and provide an algorithm to help manage intraoperatively diagnosed FNS.

METHODS

Operative records of 1484 presumed sporadic VS resections between January 2012 and December 2021 were reviewed, and patients with intraoperatively diagnosed FNSs were identified. Clinical data and preoperative imaging were retrospectively reviewed for features suggestive of FNS, and factors associated with good postoperative facial nerve function (House-Brackmann [HB] grade ≤ 2) were identified. A preoperative imaging protocol for suspected VS and recommendations for surgical decision-making following an intraoperative FNS diagnosis were created.

RESULTS

Nineteen patients (1.3%) with FNSs were identified. All patients had normal facial motor function preoperatively. In 12 patients (63%), preoperative imaging demonstrated no features suggestive of FNS, with the remainder showing subtle enhancement of the geniculate/labyrinthine facial segment, widening/erosion of the fallopian canal, or multiple tumor nodules in retrospect. Eleven (57.9%) of the 19 patients underwent a retrosigmoid craniotomy, and in the remaining patients, a translabyrinthine (n = 6) or transotic (n = 2) approach was used. Following FNS diagnosis, 6 (32%) of the tumors underwent gross-total resection (GTR) and cable nerve grafting, 6 (32%) underwent subtotal resection (STR) and bony decompression of the meatal facial nerve segment, and 7 (36%) underwent bony decompression only. All patients undergoing subtotal debulking or bony decompression exhibited normal postoperative facial function (HB grade I). At the last clinical follow-up, patients who underwent GTR with a facial nerve graft had HB grade III (3 of 6 patients) or IV facial function. Tumor recurrence/regrowth occurred in 3 patients (16%), all of whom had been treated with either bony decompression or STR.

CONCLUSIONS

Intraoperative diagnosis of an FNS during a presumed VS resection is rare, but its incidence can be reduced further by maintaining a high index of suspicion and undertaking further imaging in patients with atypical clinical or imaging features. If an intraoperative diagnosis does occur, conservative surgical management with bony decompression of the facial nerve only is recommended, unless there is significant mass effect on surrounding structures.

Comparison of Tumor Control After Stereotactic Radiosurgery or Pencil Beam Proton Therapy for Newly Diagnosed Clival Chordomas: A Single-Center Retrospective Study

OBJECTIVE

To compare outcomes of proton radiation therapy (PRT), stereotactic radiosurgery (SRS), and x-ray-based radiation with an SRS boost (XRT + SRS) for newly diagnosed clival chordoma.

METHODS

Consecutive patients who underwent PRT or SRS in our facility were retrospectively reviewed.

RESULTS

A total of 59 patients were identified (PRT, 36; SRS, 11; XRT + SRS, 12). The mean age (± standard deviation) was 46 ± 20 years, with 54% being male. The mean tumor diameter (± standard deviation) was 3.7 ± 1.5 cm, and 21 (36%) involved the lower clivus. Gross total or near-total resection was attained in 27 patients (46%), all of whom received PRT. PRT was administered with a median prescribed dose of 70.8 Gy (range, 66.0-76.0). SRS involved a median marginal dose of 16 Gy (range, 14-20) and a median maximal dose of 36 Gy (range, 30-45). The XRT + SRS group was treated with an SRS marginal dose of 12.5 Gy (range, 10-20), a maximal dose of 27 Gy (range, 20-40), and an XRT prescription dose of 50.4 Gy (range, 45.0-59.4). Fifteen recurrences were observed (PRT, 6; SRS, 5; XRT + SRS, 4). For the entire cohort (n = 59), recurrence was associated with the degree of resection (P = 0.042), but not with radiation groups (P = 0.98). For patients after subtotal resection or biopsy (n = 32), the SRS ± XRT group was associated with few recurrences (hazard ratio, 0.260; 95% confidence interval, 0.069-0.98; P = 0.046).

CONCLUSIONS

Patients after subtotal resection or biopsy may benefit from the incorporation of SRS.

Signatures of Electrical Stimulation Driven Network Interactions in the Human Limbic System

Stimulation-evoked signals are starting to be used as biomarkers to indicate the state and health of brain networks. The human limbic network, often targeted for brain stimulation therapy, is involved in emotion and memory processing. Previous anatomic, neurophysiological, and functional studies suggest distinct subsystems within the limbic network (Rolls, 2015). Studies using intracranial electrical stimulation, however, have emphasized the similarities of the evoked waveforms across the limbic network. We test whether these subsystems have distinct stimulation-driven signatures. In eight patients (four male, four female) with drug-resistant epilepsy, we stimulated the limbic system with single-pulse electrical stimulation. Reliable corticocortical evoked potentials (CCEPs) were measured between hippocampus and the posterior cingulate cortex (PCC) and between the amygdala and the anterior cingulate cortex (ACC). However, the CCEP waveform in the PCC after hippocampal stimulation showed a unique and reliable morphology, which we term the "limbic Hippocampus-Anterior nucleus of the thalamus-Posterior cingulate, HAP-wave." This limbic HAP-wave was visually distinct and separately decoded from the CCEP waveform in ACC after amygdala stimulation. Diffusion MRI data show that the measured end points in the PCC overlap with the end points of the parolfactory cingulum bundle rather than the parahippocampal cingulum, suggesting that the limbic HAP-wave may travel through fornix, mammillary bodies, and the anterior nucleus of the thalamus (ANT). This was further confirmed by stimulating the ANT, which evoked the same limbic HAP-wave but with an earlier latency. Limbic subsystems have unique stimulation-evoked signatures that may be used in the future to help network pathology diagnosis.SIGNIFICANCE STATEMENT The limbic system is often compromised in diverse clinical conditions, such as epilepsy or Alzheimer's disease, and characterizing its typical circuit responses may provide diagnostic insight. Stimulation-evoked waveforms have been used in the motor system to diagnose circuit pathology. We translate this framework to limbic subsystems using human intracranial stereo EEG (sEEG) recordings that measure deeper brain areas. Our sEEG recordings describe a stimulation-evoked waveform characteristic to the memory and spatial subsystem of the limbic network that we term the "limbic HAP-wave." The limbic HAP-wave follows anatomic white matter pathways from hippocampus to thalamus to the posterior cingulum and shows promise as a distinct biomarker of signaling in the human brain memory and spatial limbic network.

EEG Source Localization in Temporal Encephaloceles: Concordance With Surgical Resection and Clinical Outcomes

PURPOSE

Temporal encephaloceles are a cause of drug-resistant temporal lobe epilepsy; however, their relationship with epileptogenesis is unclear, and optimal surgical resection is uncertain. EEG source localization (ESL) may guide surgical decision-making.

METHODS

We reviewed patients at Mayo Clinic Rochester with drug-resistant temporal lobe epilepsy and temporal encephaloceles, who underwent limited resection and had 1-year outcomes. EEG source localization was performed using standard density scalp EEG of ictal and interictal activity. Distance from dipole and standardized low-resolution brain electromagnetic tomography (sLORETA) solutions to the encephalocele were measured. Concordance of ESL with encephalocele and surgical resection was compared with 1-year surgical outcomes.

RESULTS

Seventeen patients met criteria. The mean distances from ESL results to encephalocele center for dipole and sLORETA analyses were 23 mm (SD 9) and 22 mm (SD 11), respectively. Ten patients (55.6%) had Engel I outcomes at 1 year. Dipole-encephalocele distance and sLORETA-encephalocele distance were significantly longer in patients with Engel I outcome and patients whose encephalocele was contained by sLORETA had worse outcome as well; however, multiple logistic regression analysis found that only containment of encephalocele by the sLORETA current density was significant (P < 0.05), odds ratio 0.12 (95% confidence interval [0.021, 0.71]).

CONCLUSIONS

EEG source localization of scalp EEG localizes near encephaloceles, however, typically not in the encephalocele itself; this may be due to scalp EEG sampling propagated activity or alternatively that the seizure onset zone extends beyond the herniated cortex. Surprisingly, we observed increased ESL to encephalocele distances in patients with excellent surgical outcomes. Larger cohort studies including intracranial EEG data are needed to further explore this finding.

Surgical Anatomy of the Microscopic and Endoscopic Transorbital Approach to the Middle Fossa and Cavernous Sinus: Anatomo-Radiological Study with Clinical Applications

BACKGROUND

The transorbital approaches (TOAs) have acquired growing notoriety, thanks to their ability to offer alternative corridors to the skull base. However, the limited access and the unfamiliarity with this surgical perspective make recognition of key landmarks difficult, especially for less experienced surgeons. The study wants to offer a detailed description of the anatomy to comprehend the potential and limitations of TOAs.

METHODS

Measurements of the orbit region and the surrounding areas were performed on two hundred high-resolution CT scans and thirty-nine dry skulls. Five specimens were dissected to illustrate the TOA, and one was used to perform the extradural clinoidectomy. Three clinical cases highlighted the surgical applications.

RESULTS

A step-by-step description of the key steps of the TOA was proposed and a comparison with the transcranial anterior clinoidectomy was discussed. The mean work distance was 6.1 ± 0.4 cm, and the lateral working angle increased 20 ± 5.4° after removing the lateral orbital rim.

CONCLUSIONS

TOAs are indicated in selected cases when tumor involves the lateral portion of the cavernous sinus or the middle skull base, obtaining a direct decompression of the optic nerve and avoiding excessive manipulation of the neurovascular structures. Comprehension of surgical anatomy of the orbit and its surrounding structures is essential to safely perform these approaches.

Multicenter Survival Analysis and Application of an Olfactory Neuroblastoma Staging Modification Incorporating Hyams Grade

Importance

Current olfactory neuroblastoma (ONB) staging systems inadequately delineate locally advanced tumors, do not incorporate tumor grade, and poorly estimate survival and recurrence.

Objective

The primary aims of this study were to (1) examine the clinical covariates associated with survival and recurrence of ONB in a modern-era multicenter cohort and (2) incorporate Hyams tumor grade into existing staging systems to assess its ability to estimate survival and recurrence.

Design, Setting, and Participants

This retrospective, multicenter, case-control study included patients with ONB who underwent treatment between January 1, 2005, and December 31, 2021, at 9 North American academic medical centers.

Intervention

Standard-of-care ONB treatment.

Main Outcome and Measures

The main outcomes were overall survival (OS), disease-free survival (DFS), and disease-specific survival (DSS) as C statistics for model prediction.

Results

A total of 256 patients with ONB (mean [SD] age, 52.0 [15.6] years; 115 female [44.9%]; 141 male [55.1%]) were included. The 5-year rate for OS was 83.5% (95% CI, 78.3%-89.1%); for DFS, 70.8% (95% CI, 64.3%-78.0%); and for DSS, 94.1% (95% CI, 90.5%-97.8%). On multivariable analysis, age, American Joint Committee on Cancer (AJCC) stage, involvement of bilateral maxillary sinuses, and positive margins were associated with OS. Only AJCC stage was associated with DFS. Only N stage was associated with DSS. When assessing the ability of staging systems to estimate OS, the best-performing model was the novel modification of the Dulguerov system (C statistic, 0.66; 95% CI, 0.59-0.76), and the Kadish system performed most poorly (C statistic, 0.57; 95% CI, 0.50-0.63). Regarding estimation of DFS, the modified Kadish system performed most poorly (C statistic, 0.55; 95% CI, 0.51-0.66), while the novel modification of the AJCC system performed the best (C statistic, 0.70; 95% CI, 0.66-0.80). Regarding estimation of DSS, the modified Kadish system was the best-performing model (C statistic, 0.79; 95% CI, 0.70-0.94), and the unmodified Kadish performed the worst (C statistic, 0.56; 95% CI, 0.51-0.68). The ability for novel ONB staging systems to estimate disease progression across stages was also assessed. In the novel Kadish staging system, patients with stage VI disease were approximately 7 times as likely to experience disease progression as patients with stage I disease (hazard ratio [HR], 6.84; 95% CI, 1.60-29.20). Results were similar for the novel modified Kadish system (HR, 8.99; 95% CI, 1.62-49.85) and the novel Dulguerov system (HR, 6.86; 95% CI, 2.74-17.18).

Conclusions and Relevance

The study findings indicate that 5-year OS for ONB is favorable and that incorporation of Hyams grade into traditional ONB staging systems is associated with improved estimation of disease progression.

Automated sleep classification with chronic neural implants in freely behaving canines

Objective.Long-term intracranial electroencephalography (iEEG) in freely behaving animals provides valuable electrophysiological information and when correlated with animal behavior is useful for investigating brain function.Approach.Here we develop and validate an automated iEEG-based sleep-wake classifier for canines using expert sleep labels derived from simultaneous video, accelerometry, scalp electroencephalography (EEG) and iEEG monitoring. The video, scalp EEG, and accelerometry recordings were manually scored by a board-certified sleep expert into sleep-wake state categories: awake, rapid-eye-movement (REM) sleep, and three non-REM sleep categories (NREM1, 2, 3). The expert labels were used to train, validate, and test a fully automated iEEG sleep-wake classifier in freely behaving canines.Main results. The iEEG-based classifier achieved an overall classification accuracy of 0.878 ± 0.055 and a Cohen's Kappa score of 0.786 ± 0.090. Subsequently, we used the automated iEEG-based classifier to investigate sleep over multiple weeks in freely behaving canines. The results show that the dogs spend a significant amount of the day sleeping, but the characteristics of daytime nap sleep differ from night-time sleep in three key characteristics: during the day, there are fewer NREM sleep cycles (10.81 ± 2.34 cycles per day vs. 22.39 ± 3.88 cycles per night;p< 0.001), shorter NREM cycle durations (13.83 ± 8.50 min per day vs. 15.09 ± 8.55 min per night;p< 0.001), and dogs spend a greater proportion of sleep time in NREM sleep and less time in REM sleep compared to night-time sleep (NREM 0.88 ± 0.09, REM 0.12 ± 0.09 per day vs. NREM 0.80 ± 0.08, REM 0.20 ± 0.08 per night;p< 0.001).Significance.These results support the feasibility and accuracy of automated iEEG sleep-wake classifiers for canine behavior investigations.

Treatment outcome of metastasis to the pituitary gland: a case series of 21 patients with pathological diagnosis

OBJECTIVE

The aim of this study was to report the treatment course of histologically confirmed metastases to the pituitary gland (pituitary metastasis).

METHODS

The Mayo data explorer was used to find patients with pituitary metastasis. Twenty-one patients were identified between the years 2001 and 2021, and their data were retrospectively collected.

RESULTS

The most common primary cancer origin was lung in men (45%) and breast in women (33%). The median age was 66 years (IQR 56-68 years). Patients presented with headache (67% [14/21]), vision problems (86% [18/21]), anterior hypopituitarism (71% [15/21]), and arginine vasopressin deficiency (38% [8/21]). Pituitary metastases were found before the diagnosis of the primary cancer in 5 patients (24%). The mean ± SD tumor size was 2.0 ± 0.7 cm, and 90% (19/21) presented as a solitary pituitary mass with no other intracranial metastatic lesions. Common radiological features were pituitary stalk thickening (90% [19/21]), cavernous sinus involvement (71% [15/21]), and constriction at the diaphragma sellae (52% [11/21]). Transsphenoidal surgery was performed in 20 patients, and subtotal resection was most frequently attained (76% [16/21]). Fourteen patients (67%) had adjuvant radiation therapy, and 15 patients (71%) were treated with systemic therapy. The median time from surgery to the initiation of radiation therapy was 16 days (IQR 11-21 days), and that from surgery to the initiation of systemic therapy was 5.0 months (IQR 1.5-14 months). During management, headaches improved in 57% (8/14) and vision problems improved in 61% (11/18) of cases; new hypopituitarism occurred in 5 patients. Six patients developed recurrence, and the median progression-free survival was 24 months (95% CI 5.4-43 months). After recurrence, 1 patient with adenoid cystic carcinoma was treated with rescue radiotherapy twice, and 4 patients responded well to systemic therapy. The median overall survival (OS) was 25 months (95% CI 7.1-43 months). The mean OS was better in patients with neuroendocrine lung tumor (261 months) and papillary thyroid carcinoma (80 months) and worse in patients with small cell lung cancer (4 months) and unknown origin (5 months).

CONCLUSIONS

Surgery with or without adjuvant radiotherapy is effective for mass reduction, rapid symptomatic improvement of vision and headaches, and definitive diagnosis. Even after local tumor control failure, some patients still benefit from radiation and/or systemic therapy.

Anatomical Step-by-Step Dissection of Complex Skull Base Approaches for Trainees: Surgical Anatomy of the Endoscopic Endonasal Approach to the Sellar and Parasellar Regions

Introduction  Surgery of the sellar and parasellar regions can be challenging due to the complexity of neurovascular relationships. The main goal of this study is to develop an educational resource to help trainees understand the pertinent anatomy and procedural steps of the endoscopic endonasal approaches (EEAs) to the sellar and parasellar regions. Methods  Ten formalin-fixed latex-injected specimens were dissected. Endoscopic endonasal transsphenoidal transsellar, transtuberculum-transplanum, and transcavernous approaches were performed by a neurosurgery trainee, under supervision from the senior authors and a PhD in anatomy with advanced neuroanatomy experience. Dissections were supplemented with representative case applications. Results  Endoscopic endonasal transsphenoidal approaches afford excellent direct access to sellar and parasellar regions. After a wide sphenoidotomy, a limited sellar osteotomy opens the space to sellar region and medial portion of the cavernous sinus. To reach the suprasellar space (infrachiasmatic and suprachiasmatic corridors), a transplanum-prechiasmatic sulcus-transtuberculum adjunct is needed. The transcavernous approach gains access to the contents of the cavernous sinus and both medial (posterior clinoid and interpeduncular cistern) and lateral structures of the retrosellar region. Conclusion  The anatomical understanding and technical skills required to confidently remove skull base lesions with EEAs are traditionally gained after years of specialized training. We comprehensively describe EEAs to sellar and parasellar regions for trainees to build knowledge and improve familiarity with these approaches and facilitate comprehension and learning in both the surgical anatomy laboratory and the operating room.

Glucocorticoid withdrawal syndrome following surgical remission of endogenous hypercortisolism: a longitudinal observational study

OBJECTIVE

Glucocorticoid withdrawal syndrome (GWS) is a scarcely studied phenomenon that complicates the recovery following surgical remission of hypercortisolism. We aimed to characterize the presence and trajectory of glucocorticoid withdrawal symptoms in the postoperative period and to determine presurgical predictors of GWS severity.

DESIGN

Longitudinal observational study.

METHODS

Glucocorticoid withdrawal symptoms were prospectively evaluated weekly for the first 12 weeks following surgical remission of hypercortisolism. Quality of life (CushingQoL and Short-Form-36) and muscle function (hand grip strength and sit-to-stand test) were assessed at the baseline and at 12 weeks after surgery.

RESULTS

Prevalent symptoms were myalgias and arthralgias (50%), fatigue (45%), weakness (34%), sleep disturbance (29%), and mood changes (19%). Most symptoms persisted, while myalgias, arthralgias, and weakness worsened during weeks 5-12 postoperatively. At 12 weeks after surgery, normative hand grip strength was weaker than at baseline (mean Z-score delta -0.37, P = .009), while normative sit-to-stand test performance improved (mean Z-score delta 0.50, P = .013). Short-Form-36 Physical Component Summary score worsened (mean delta -2.6, P = .015), but CushingQoL score improved (mean delta 7.8, P < .001) at 12 weeks compared to baseline. Cushing syndrome (CS) clinical severity was predictive of postoperative GWS symptomology.

CONCLUSION

Glucocorticoid withdrawal symptoms are prevalent and persistent following surgical remission of hypercortisolism with baseline CS clinical severity predictive of postoperative GWS symptom burden. Differential changes observed in muscle function and quality of life in the early postoperative period may reflect the competing influences of GWS and recovery from hypercortisolism.

The Effect of Age on Facial Nerve Recovery After Vestibular Schwannoma Resection

OBJECTIVE

The objective of this study is to assess the influence of age on facial nerve recovery after microsurgical resection of sporadic vestibular schwannoma.

STUDY DESIGN

A historical cohort study was performed.

SETTING

The study was performed at a tertiary referral center.

PATIENTS

The studied cohort included patients with a House-Brackmann (HB) Grade III or worse in the immediate postoperative period.

INTERVENTIONS

The studied intervention was microsurgical resection.

MAIN OUTCOME MEASURES

The main outcome measure was complete recovery of facial nerve function to HB Grade I at least 12 months postoperatively.

RESULTS

There were six patients with intracanalicular tumors and 100 with cerebellopontine angle (CPA) tumors eligible for study. Given the few patients with intracanalicular tumors, no further analysis was pursued in this subset. For patients with CPA tumors, a multivariable analysis of several patient and tumor characteristics demonstrated age at surgery (odds ratio for 10-year increase of 0.68; 95% confidence interval [CI], 0.47-0.98; p = 0.04) and immediate postoperative HB grade (odds ratio for one-grade increase of 0.27; 95% CI, 0.15-0.50; p < 0.001) to be jointly significantly associated with complete recovery to HB Grade I, indicating that the likelihood of complete facial nerve recovery was higher for younger patients and for those with better immediate postoperative HB grades. For example, the predicted probability of complete facial nerve recovery for a 30-year-old with immediate postoperative HB Grade III was 0.76 (or 76% when expressed as a percentage), whereas the predicted probability for a 50-year-old with immediate postoperative HB Grade V was only 0.10.

CONCLUSIONS

After considering immediate postoperative HB grade, younger age at surgery was independently significantly associated with complete facial nerve recovery, which can assist in intraoperative decision-making regarding extent of resection and postoperative counseling.

Subtotal gland resection for MR negative Cushing disease with no detectable tumor on gland exploration: operative video

MRI-Negative Cushing disease is a very difficult disease to treat medically and surgically. In the past, after negative gland exploration, hemihypophysectomy was commonly performed on the localizing side of inferior petrosal sampling. However, this generally resulted in 50% remission/cure rates. Therefore, other techniques have arisen based on the percent chance of microadenoma tumor being present in the gland. Subtotal gland resection is a technique aimed at removing 75% of the gland that results in a similar chance of remission and a 10% chance of pituitary dysfunction. In this video, the authors demonstrate this important technique for MRI-Negative Cushing disease. The video can be found here: https://thejns.org/doi/abs/10.3171/2023.4.FOCVID2320.

The utility of PET for detecting corticotropinomas in Cushing disease: a scoping review

While magnetic resonance imaging (MRI) is the current standard imaging method for diagnosing and localizing corticotropinomas in Cushing disease, it can fail to detect adenomas in up to 40% of cases. Recently, positron emission tomography (PET) has shown promise as a diagnostic tool to detect pituitary adenomas in Cushing disease. We perform a scoping review to characterize the uses of PET in diagnosing Cushing disease, with a focus on describing the types of PET investigated and defining PET-positive disease. A scoping review was conducted following the PRISMA-ScR guidelines. Thirty-one studies fulfilled our inclusion criteria, consisting of 10 prospective studies, 8 retrospective studies, 11 case reports, and 2 illustrative cases with a total of 262 patients identified. The most commonly utilized PET modalities in prospective/retrospective studies were FDG PET (n = 5), MET PET (n = 5), 68 Ga-DOTATATE PET (n = 2), 13N-ammonia PET (n = 2), and 68 Ga-DOTA-CRH PET (n = 2). MRI positivity ranged from 13 to 100%, while PET positivity ranged from 36 to 100%. In MRI-negative disease, PET positivity ranged from 0 to 100%. Five studies reported the sensitivity and specificity of PET, which ranged from 36 to 100% and 50 to 100%, respectively. PET shows promise in detecting corticotropinomas in Cushing disease, including MRI-negative disease. MET PET has been highly investigated and has demonstrated excellent sensitivity and specificity. However, preliminary studies with FET PET and 68 Ga-DOTA-CRH PET show promise for achieving high sensitivity and specificity and warrant further investigation.

Immunohistochemical markers predicting long-term recurrence following clival and spinal chordoma resection: a multicenter study

OBJECTIVE

Chordomas are rare tumors from notochordal remnants and account for 1%-4% of all primary bone malignancies, often arising from the clivus and sacrum. Despite margin-negative resection and postoperative radiotherapy, chordomas often recur. Further, immunohistochemical (IHC) markers have not been assessed as predictive of chordoma recurrence. The authors aimed to identify the IHC markers that are predictive of postoperative long-term (≥ 1 year) chordoma recurrence by using trained multiple tree-based machine learning (ML) algorithms.

METHODS

The authors reviewed the records of patients who had undergone treatment for clival and spinal chordomas between January 2017 and June 2021 across the Mayo Clinic enterprise (Minnesota, Florida, and Arizona). Demographics, type of treatment, histopathology, and other relevant clinical factors were abstracted from each patient record. Decision tree and random forest classifiers were trained and tested to predict long-term recurrence based on unseen data using an 80/20 split.

RESULTS

One hundred fifty-one patients diagnosed and treated for chordomas were identified: 58 chordomas of the clivus, 48 chordomas of the mobile spine, and 45 chordomas sacrococcygeal in origin. Patients diagnosed with cervical chordomas were the oldest among all groups (58 ± 14 years, p = 0.009). Most patients were male (n = 91, 60.3%) and White (n = 139, 92.1%). Most patients underwent resection with or without radiation therapy (n = 129, 85.4%). Subtotal resection followed by radiation therapy (n = 51, 33.8%) was the most common treatment modality, followed by gross-total resection then radiation therapy (n = 43, 28.5%). Multivariate analysis showed that S100 and pan-cytokeratin are more likely to predict the increase in the risk of postoperative recurrence (OR 3.67, 95% CI 1.09-12.42, p= 0.03; and OR 3.74, 95% CI 0.05-2.21, p = 0.02, respectively). In the decision tree analysis, a clinical follow-up > 1897 days was found in 37% of encounters and a 90% chance of being classified for recurrence (accuracy = 77%). Random forest analysis (n = 500 trees) showed that patient age, type of surgical treatment, location of tumor, S100, pan-cytokeratin, and EMA are the factors predicting long-term recurrence.

CONCLUSIONS

The IHC and clinicopathological variables combined with tree-based ML tools successfully demonstrated a high capacity to identify recurrence patterns with an accuracy of 77%. S100, pan-cytokeratin, and EMA were the IHC drivers of recurrence. This shows the power of ML algorithms in analyzing and predicting outcomes of rare conditions of a small sample size.

Stereo-EEG localization of midline onset seizures on scalp EEG

PURPOSE

The objective of this study was to describe the sEEG-defined seizure onset zone (SOZ), seizure semiology, presurgical evaluations, surgical intervention and outcome in patients with midline onset noninvasive phase I monitoring.

METHODS

A single center sEEG database was reviewed to identify patients with seizures onset predominantly involving midline electrodes (FZ, CZ, PZ, OZ) on scalp EEG. Data abstracted included clinical factors, seizure semiology graded into lobar segmentation, imaging and electrographic findings, sEEG plan, interventions, and outcome.

RESULTS

Twelve patients were identified (8 males, median age of sEEG 28 years) out of 100 cases of sEEG performed from January 2015-September 2019. "Frontal lobe" seizure semiology was the most common. sEEG-defined SOZ were frontal (5), diffuse (1), multifocal (1), frontal and insular (1), frontal and cingulate (1), insular (1), cingulate (1), and mesial temporal (1). CZ and/or FZ scalp EEG changes were present for all patients with SOZ involving the frontal, cingulate, and insular regions. PZ/OZ scalp involvement was present in one patient with mesial temporal SOZ. Four patients underwent a definitive resective or ablative surgery, and the remaining patients underwent a palliative intervention. Of those with follow-up information available, 8/11 had seizure reduction by ≥ 50%, including 4 with an Engel I outcome. No clinical factors were associated with outcome.

CONCLUSIONS

SOZ for midline onset seizures from noninvasive phase I monitoring was most commonly in the frontal, cingulate, and insular regions. A complex cortical network between these regions may explain overlap in semiology and scalp EEG findings. While the number rendered seizure-free was limited, a significant proportion experienced a reasonably favorable outcome justifying use of sEEG to identify surgical options in these patients.