Calculating the tumor volume of acoustic neuromas: Comparison of ABC/2 formula with planimetry method

Neurosurgical short-term outcomes for pediatric medulloblastoma patients and molecular correlations: a 10-year single-center observation cohort study

This study examined the risk factors for short-term outcomes, focusing particularly on the associations among molecular subgroups. The analysis focused on the data of pediatric patients with medulloblastoma between 2013 and 2023, as well as operative complications, length of stay from surgery to adjuvant treatment, 30-day unplanned reoperation, unplanned readmission, and mortality. 148 patients were included. Patients with the SHH TP53-wildtype exhibited a lower incidence of complications (45.2% vs. 66.0%, odds ratio [OR] 0.358, 95% confidence interval [CI] 0.160 - 0.802). Female sex (0.437, 0.207 - 0.919) was identified as an independent protective factor for complications, and brainstem involvement (1.900, 1.297 - 2.784) was identified as a risk factor. Surgical time was associated with an increased risk of complications (1.004, 1.001 - 1.008), duration of hospitalization (1.006, 1.003 - 1.010), and reoperation (1.003, 1.001 - 1.006). Age was found to be a predictor of improved outcomes, as each additional year was associated with a 14.1% decrease in the likelihood of experiencing a prolonged length of stay (0.859, 0.772 - 0.956). Patients without metastasis exhibited a reduced risk of reoperation (0.322, 0.133 - 0.784) and readmission (0.208, 0.074 - 0.581). There is a significant degree of variability in the occurrence of operative complications in pediatric patients with medulloblastoma. SHH TP53-wildtype medulloblastoma is commonly correlated with a decreased incidence of complications. The short-term outcomes of patients are influenced by various unmodifiable endogenous factors. These findings could enhance the knowledge of onconeurosurgeons and alleviate the challenges associated with patient/parent education through personalized risk communication. However, the importance of a dedicated center with expertise surgical team and experienced neurosurgeon in improving neurosurgical outcomes appears self-evident.

The insertion and management of an external ventricular drain in pediatric patients with hydrocephalus associated with medulloblastoma

An external ventricular drain (EVD) is used to facilitate cerebrospinal fluid (CSF) removal in medulloblastoma patients suffering from hydrocephalus. It is essential to recognize that EVD management plays a crucial role in influencing the incidence of drain-related complications. However, the ideal method for EVD management remains undetermined. Our research sought to examine the safety of EVD placement and the impact of EVD on the incidences of intracranial infections, postresection hydrocephalus, and posterior fossa syndrome (PFS). We conducted a single-center observational study involving a cohort of 120 pediatric medulloblastoma patients who were treated from 2017 to 2020. The rates of intracranial infection, postresection hydrocephalus, and PFS were 9.2%, 18.3%, and 16.7%, respectively. EVD did not influence the occurrence of intracranial infection (p = 0.466), postresection hydrocephalus (p = 0.298), or PFS (p = 0.212). A gradual EVD weaning protocol correlated with an elevated incidence of postresection hydrocephalus (p = 0.033), whereas a rapid weaning approach resulted in 4.09 ± 0.44 fewer drainage days (p < 0.001) than the gradual weaning strategy. EVD placement (p = 0.010) and intracranial infection (p = 0.002) were linked to delayed speech return, whereas a longer duration of drainage was conducive to the recovery of language function (p = 0.010). EVD insertion was not correlated with the incidence of intracranial infection, postoperative hydrocephalus, or PFS. The optimal EVD management method should encompass a rapid EVD weaning strategy, followed by prompt drain closure. We have presented additional evidence to improve the safety of EVD insertion and management in neurosurgical patients to ultimately facilitate the establishment of standardized institutional/national implementation and management protocols.

Incidence and Risk Factors for Necessitating Cerebrospinal Fluid Diversion Following Medulloblastoma Surgery in Children

BACKGROUND

There are insufficient data on pediatric patients with medulloblastoma who require cerebrospinal fluid (CSF) diversion following resection. Therefore, this study aimed to determine the incidence and the characteristics associated with it in this subset of patients.

METHODS

We conducted a single-center, retrospective, observational cohort study of patients aged 18 years or less who underwent medulloblastoma resection at our department between 2010 and 2021. The primary outcome was the incidence of CSF diversion surgery required after resection. Participant demographics, tumor biology, and interventions were analyzed using univariate- and multivariate-adjusted models.

RESULTS

Of the 183 patients admitted to our department, 131 (71.6%) participated in this study. The incidence of permanent CSF diversion was 26.0% (95% confidence interval [CI]: 18.7 to 34.3). Factors independently associated with requirement of permanent CSF diversion were medulloblastoma volume >46.4 cm³ (odds ratio [OR]: 2.919, 95% CI: 1.191 to 7.156) and CSF channel invasion (OR: 2.849, 95% CI: 1.142 to 7.102). The duration of manifestation may be a covariate of tumor volume with increased risk of requirement for permanent CSF diversion (OR: 1.006, 95% CI: 1.000 to 1.013), and tumor volume may be a predictor in patients who underwent subtotal resection (OR: 4.900, 95% CI: 0.992 to 24.208, P = 0.05). Finally, patients who required permanent CSF diversion were divided according to medulloblastoma molecular subgroups, and no significant differences were found.

CONCLUSION

We report major predictive factors for permanent CSF diversion surgery in patients with medulloblastoma. Our study suggests that the presence of postresection hydrocephalus is not high enough to warrant permanent, prophylactic CSF diversion in all patients.

Reducing Gadolinium Exposure in Patients Undergoing Monitoring for Meningiomas

Background Due to the non-malignant and slow-growing nature of many meningiomas, surveillance with serial magnetic resonance imaging (MRI) serves as an acceptable management plan. However, repeated imaging with gold-standard contrast-based studies may lead to contrast-associated adverse effects. Non-gadolinium T2 sequences may serve as a suitable alternative without the risk of adverse effects of contrast. Thus, this study sought to investigate the agreement between post-contrast T1 and non-gadolinium T2 MRI sequences in the measurement of meningioma growth. Methodology The Virginia Commonwealth University School of Medicine (VCU SOM) brain tumor database was used to create a cohort of meningioma patients and determine the number of patients who had T1 post-contrast imaging accompanied by readily measurable imaging from either T2 fast spin echo (FSE) or T2 fluid-attenuated inversion recovery (FLAIR) sequences. Measurements of the largest axial and perpendicular diameters of each tumor were conducted by two independent observers using T1 post-contrast, T2 FSE, and T2 FLAIR imaging series. Lin's concordance correlation coefficient (CCC) was calculated to assess inter-rater reliability between observers and agreement between measurements of tumor diameter among the different imaging sequences. Results In total, 33 patients (average age = 72.1 ± 12.9 years, 90% female) with meningiomas were extracted from our database, with 22 (66.7%) undergoing T1 post-contrast imaging accompanied with readily measurable imaging from T2 FSE and/or T2 FLAIR sequences. The inter-rater reliability between the measurements of T1 axial and perpendicular diameters was 0.96 (95% confidence interval (CI) = 0.92-0.98) and 0.92 (95% CI = 0.83-0.97), respectively. The inter-rater reliability between the measurements of T2 axial perpendicular diameters was 0.93 (95% = CI 0.92-0.97) and 0.89 (95% CI = 0.74-0.95), respectively. The agreements between the measurement of T1 and T2 FSE axial diameter by each observer were 0.97 (95% CI = 0.93-0.98) and 0.92 (95% CI = 0.81-0.97). The agreements between the measurements of T1 and T2 FSE perpendicular diameter measurements by each observer were 0.98 (95% CI = 0.95-0.99) and 0.88 (95% CI = 0.73-0.95). Conclusions Two-thirds of our patients had meningiomas that were readily measurable on either T2 FSE or T2 FLAIR sequences. Additionally, there was excellent inter-rater reliability between the observers in our study as well as an agreement between individual measurements of T1 post-contrast and T2 FSE tumor diameters. These findings suggest that T2 FSE may serve as a safe and similarly effective surveillance method for the long-term management of meningioma patients.

Growth Analysis of Untreated Meningiomas under Observation

BACKGROUND

 When meningiomas are small or asymptomatic, the decision to observe rather than treat requires balancing the growth potential of the lesion with the outcome and side effects of treatment. The aim of this study is to characterize the growth patterns of untreated meningiomas to better inform the clinical decision-making process.

METHODS

 Patients with meningiomas were identified from 2005 to 2015. Those without treatment who had been followed for 1.5 years, with three magnetic resonance imaging (MRI) scans, were identified. Scans were measured with orthogonal diameters, geometric mean diameters, and volumes using the ABC/2 method. Regression modeling determined what growth pattern these parameters best approximated.

RESULTS

 Two hundred and fifteen MRI scans for 34 female (82.9%) and 7 male (17%) patients with 43 tumors were evaluated. Initial tumor volumes ranged from 0.13 to 9.98 mL. The mean and median initial volumes were 2.44 and 1.52 mL, respectively. Follow-up times ranged from 21 to 144 months, with a median of 70 months. There were 12 tumors (28%) whose growth rates were significantly greater than zero. For all tumors, use of a linear regression model allowed accurate prediction of the future size using prior data.

CONCLUSION

 Three-quarters of presumptive meningiomas managed conservatively do not grow significantly. The remainder have significant growth over time, and the behavior could be approximated with linear regression models.

Progression of Hearing Loss in Observed Non-Growing Vestibular Schwannoma

OBJECTIVE

To assess hearing outcomes in observed vestibular schwannoma (VS) with focus on non-growing tumors.

STUDY DESIGN

Retrospective review.

SETTING

Two tertiary neurotology centers.

PATIENTS AND INTERVENTIONS

Patients with sporadic VS undergoing at least 3 years' observation.

MAIN OUTCOME MEASURES

Changes in pure tone averages (PTA) and word recognition scores (WRS) normalized to the contralateral ear.

RESULTS

During the study period, 39 of 105 included patients (37.1%) had tumor growth. Patients with tumor growth had a mean normalized increase in PTA of 8.0 dB HL (p = 0.008) corresponding to a normalized average worsening of their PTA of 1.8 dB per year. Patients with non-growing tumors less than 5 mm in maximal dimension did not have significant ongoing normalized hearing loss (p > 0.05). Patients with non-growing tumors more than or equal to 5 mm had a mean normalized increase in PTA of 7.4 dB HL (p = 0.001) corresponding to an average of 2.0 dB HL per year, which was similar to the loss observed in growing tumors regardless of size (p > 0.05). Normalized decline in PTA of at least 5 dB HL was seen in 72% of patients with growing tumors, 53% of patients with nongrowing tumors more than or equal to 5 mm, and 38% of patients with non-growing tumors less than 5 mm.

CONCLUSIONS

A long-term analysis of hearing outcomes in observed vestibular schwannoma is presented. With observation, VS more than or equal to 5 mm is associated with continued hearing loss even without tumor growth, while non-growing tumors less than 5 mm are not associated with continuing hearing loss. These data inform expectations for observed VS for providers and patients.

Novel Predictive Models for High-Value Care Outcomes Following Glioblastoma Resection

BACKGROUND

Treating patients with glioblastoma (GBM) requires extensive medical infrastructure. Individualized risk assessment for extended length of stay (LOS), nonroutine discharge disposition, and increased total hospital charges is critical to optimize delivery of care. Our study sought to develop predictive models identifying independent risk factors for these outcomes.

METHODS

We retrospectively reviewed patients undergoing GBM resection at our institution between January 2017 and September 2020. Extended LOS and elevated hospital charges were defined as values in the upper quartile of the cohort. Nonroutine discharge was defined as any disposition other than to home. Multivariate models for each outcome included covariates demonstrating P ≤ 0.10 on bivariate analysis.

RESULTS

We identified 265 patients undergoing GBM resection, with an average age of 58.2 years. 24.5% of patients experienced extended LOS, 22.6% underwent nonroutine discharge, and 24.9% incurred elevated total hospital charges. Decreasing Karnofsky Performance Status (KPS) (P = 0.004), increasing modified 5-factor frailty (mFI-5) index (P = 0.012), lower surgeon experience (P = 0.005), emergent surgery (P < 0.0001), and larger tumor volume (P < 0.0001) predicted extended LOS. Independent predictors of nonroutine discharge included older age (P = 0.02), decreasing KPS (P < 0.0001), and emergent surgery (P = 0.048). Nonprivate insurance (P = 0.011), decreasing KPS (P = 0.029), emergent surgery (P < 0.0001), and larger tumor volume (P = 0.004) predicted elevated hospital charges. These models were incorporated into an open-access online calculator (https://neurooncsurgery3.shinyapps.io/gbm_calculator/).

CONCLUSIONS

Several factors were independent predictors for at least 1 high-value care outcome, with lower KPS and emergent admission associated with each outcome. These models and our calculator may help clinicians provide individualized postoperative risk assessment to glioblastoma patients.

Development of computational models for microtesla-level magnetic brain scanning: a novel avenue for device development

BACKGROUND

Detection of locally increased blood concentration and perfusion is critical for assessment of functional cortical activity as well as diagnosis of conditions such as intracerebral hemorrhage (ICH). Current paradigms for assessment of regional blood concentration in the brain rely on computed tomography (CT), magnetic resonance imaging (MRI), and perfusion blood oxygen level dependent functional magnetic resonance imaging (BOLD-fMRI).

RESULTS

In this study, we developed computational models to test the feasibility of novel magnetic sensors capable of detecting hemodynamic changes within the brain on a microtesla-level. We show that low-field magnetic sensors can accurately detect changes in magnetic flux density and eddy current damping signals resulting from increases in local blood concentration. These models predicted that blood volume changes as small as 1.26 mL may be resolved by the sensors, implying potential use for diagnosis of ICH and assessment of regional blood flow as a proxy for cerebral metabolism and neuronal activity. We then translated findings from our computational model to demonstrate feasibility of accurate detection of modeled ICH in a simulated human cadaver setting.

CONCLUSIONS

Overall, microtesla-level magnetic scanning is feasible, safe, and has distinct advantages compared to current standards of care. Computational modeling may facilitate rapid prototype development and testing of novel medical devices with minimal risk to human participants prior to device construction and clinical trials.

Endoscopic-assisted surgical approach for butterfly glioma surgery

PURPOSE

Gliomas that spread along the white matter tracts of the corpus callosum to both hemispheres have traditionally been considered surgically challenging largely due to the relative complexity of safely achieving complete resections. We present a series of endoscopic-assisted resections of butterfly gliomas with post-operative radiological assessment of EOR and clinical outcome data.

METHODS

Retrospective review of patients who underwent surgical resection of a butterfly glioma from 2007 to 2020. Butterfly gliomas were defined as gliomas, which appeared to arise from the corpus callosum with significant bilateral extension. All records were retrospectively reviewed with operative/clinical outcomes and complications recorded.

RESULTS

70 patients who underwent an endoscopic-assisted transcortical or interhemispheric approach for butterfly glioma resection met inclusion criteria. A unilateral transcortical approach was used in 86% of cases and an interhemispheric approach in 14%. The endoscope enhanced the visualization of the contralateral hemisphere and allowed for resection of tumor, not reached by standard microscopic visualization, in 100% of cases. 90% of resections resulted in greater than a 95% resection rate. Neurological deficits mostly consisted of motor (10%) and memory (6%) deficits and were most common with posterior tumors of the splenium.

CONCLUSION

The endoscopic-assisted transcortical or interhemispheric approach for butterfly glioma resection is effective in achieving a greater than 95% resection with minimal complications. An angled approach allows careful maneuvering around complex anatomic structures and difficult corners, and should be examined further for its clinical benefits in a prospective manner.

Risk Factors for Complications Following Lateral Skull Base Surgery and the Utility of ICU Monitoring

OBJECTIVE

To examine the role of intensive care unit (ICU) management following lateral skull base surgery for vestibular schwannoma and identify risk factors for complications warranting admission to the ICU.

STUDY DESIGN

Retrospective review.

SETTING

Tertiary referral center.

PATIENTS

Two hundred consecutive patients undergoing lateral skull base surgery for vestibular schwannomas.

INTERVENTION

Lateral skull base approach for resection of vestibular schwannoma and postoperative monitoring.

MAIN OUTCOME MEASURES

Patients were grouped if they sustained an ICU complication, a non-ICU complication, or no complication. Analysis was performed to determine patient or treatment factors that may be associated with ICU complications. Multivariate and three-way analysis of variance compared groups, and multivariate logistic regression determined adjusted odds ratios (aOR) for analyzed factors.

RESULTS

Seventeen of 200 patients sustained ICU complications (8.5%), most commonly hypertensive urgency (n = 15). Forty-six (23%) sustained non-ICU complications, and 137 (68.5%) had no complications. When controlling for age, sex, obesity, and other comorbidities, only hypertension (aOR 5.43, 95% confidence interval (CI) 1.35-21.73, p = 0.017) and tumor volume (aOR 3.29, 95% CI 1.09-9.96, p = 0.035) were independently associated with increased risk of ICU complications.

CONCLUSIONS

The necessity of intensive care following lateral skull base surgery is rare, with the primary ICU complication being hypertensive urgency. Preoperative hypertension and large tumor volume (>4500 mm3) were independently associated with increased risk for ICU complications. These findings may allow for risk stratification of patients appropriate for admission to stepdown units following resection of vestibular schwannomas. Further prospective, multi-center, randomized studies are necessary to validate these findings before systematic changes to current postoperative care practices.

Assessment of Tumor Volume Dynamics and Outcome After Radiosurgery for the Treatment of Vestibular Schwannoma: A Single-Center Experience

OBJECTIVE

To assess the factors affecting early local and audiometric outcomes in vestibular schwannoma (VS) patients treated with stereotactic radiosurgery (SRS).

STUDY DESIGN

A retrospective review of medical records.

SETTING

Tertiary referral center.

PATIENTS

Records of all adult patients who underwent SRS between 2010 and 2016 for the treatment of VS were retrospectively reviewed. Patients treated with microsurgery or multi-fractionation schemes, and those who had neurofibromatosis type 2, were excluded.

INTERVENTION

SRS, tumor volume/size measurements.

MAIN OUTCOME MEASURES

The impact of tumor volume dynamics on the early local and hearing-related outcomes, together with the factors that influence them following SRS, and comparison of different tumor size measurement methods.

RESULTS

From 2010 to 2016, 53 patients underwent single fraction SRS of 12 Gy. Median follow-up time was 32 months (range, 6-79). At the last follow-up, only one patient had clinical progression. Age less than or equal to 65 years (p = 0.04; odds ratio [OR]: 0.17; 95% confidence interval [CI]: 0.03-0.93) and baseline pure-tone average (PTA) level less than or equal to 30 dB (p = 0.03; OR: 0.90; 95% CI: 0.84-0.96) were associated with maintenance of serviceable hearing. On multivariate analysis, PTA remained significant (p = 0.01; OR: 0.04; 95% CI: 0.003-0.45). In patients with a loss of serviceable hearing, the mean volume increase tended to be higher than in the patients whose hearing was maintained. The linear measurement method underestimated, and the A × B × C/2 equation overestimated, the radiological progression compared with 3D-volumetric delineations.

CONCLUSION

During the median observation period of almost 3 years, we reported our early outcome results. Tumor volume increase may have an impact on serviceable hearing loss after SRS. Currently there is no widely accepted method for the evaluation of post-SRS response. Linear measurement and the A × B × C/2 equation produce less reliable estimates of radiological progression compared with 3D-volumetric delineations. Accurate volume measurements with 3D delineations should be considered as part of clinical routine for assessing progression and deciding on salvage therapies.

The Effect of Radiation on Meningioma Volume Change

BACKGROUND

Radiation therapy is a common treatment for meningiomas. Volume changes of meningiomas in response to radiation are not well characterized. This study seeks to quantify the volume change of meningiomas following radiation.

METHODS

Data were collected from a retrospective single-institution database of cases from 2005-2015. Tumors were measured using T1-weighted post-contrast magnetic resonance imaging. Volumes were calculated using the ABC/2 ellipsoidal approximation.

RESULTS

A total of 63 patients fit the inclusion criteria; 37 patients (59%) received radiation following resection, 19 (30%) received radiation alone, 4 (6%) received radiation following a biopsy, and 3 (5%) had unknown surgical status. A total of 39 patients (62%) had skull base meningiomas; 43 tumors were World Health Organization (WHO) grade I, and 12 tumors were WHO grade II. Thirteen patients received radiosurgery, 43 received radiotherapy, and 7 received an unknown number of treatments. Eight patients did not attain local control and were excluded from volume analyses. WHO grade I meningiomas saw an average of 33% ± 19% decrease in tumor volume; WHO grade II tumor volumes decreased by an average 30% ± 23%. Radiosurgery saw an average volume decrease of 34% ± 13%, while radiotherapy resulted in volume decrease of 31% ± 21%. For those who achieved local control, there was an average decrease in tumor size of 30% ± 19%, 30% ± 22%, and 41% ± 19% over 0.5-1.5, 2.5-3.5, and >5 years, respectively.

CONCLUSIONS

Meningiomas treated with radiation exhibit nonlinear decrease in size over time. The greatest decrease in tumor volume occurs within the first year and begins to plateau 5 years post-radiation treatment.

Tumor volume and the dural tail sign enable the differentiation of intracranial solitary fibrous tumor/hemangiopericytoma from high-grade meningioma

OBJECTIVES

Intracranial solitary fibrous tumor/hemangiopericytoma (SFT/HPC) is a rare mesenchymal neoplasm with imaging features mimicking high-grade meningioma (HGM) and can easily be misdiagnosed. We sought to determine the value of routine preoperative data in differentiating these tumors.

PATIENTS AND METHODS

Patients with confirmed SFT/HPC or HGM between January 2012 and June 2020 were identified. A total of 28 preoperative variables (including age, sex, tumor location, tumor volume, 10 traditional MRI features, and 14 peripheral blood indices) were collected for each patient. The top features were selected sequentially based on the least absolute shrinkage and selection operator (LASSO) and support vector machines-recursive feature elimination (SVM-RFE) methods. Differentiation and calibration of the classifiers were assessed by receiver operating characteristic (ROC) curves and calibration curves, respectively. Nomograms were constructed based on multivariate analysis.

RESULTS

A total of 127 patients, including 29 with SFT/HPC and 98 with HGM, were analyzed. Three features were first selected using the LASSO and SVM-RFE methods, and corresponding models were developed. Although the area under the curve (AUC) of model 1 was the highest, a comprehensive analysis suggested the superiority of model 2, which consisted only of the features tumor volume (TV) and dural tail sign (DTS) (AUC: 0.942, sensitivity: 93.10%, p-value of H-L test: 0.734, Brier score: 0.07). A risk score formula and a nomogram were constructed.

CONCLUSIONS

TV can be used to effectively identify SFT/HPC and HGM, whereas adding DTS can improve the overall prediction accuracy. As these two variables are routinely available and are easy for clinicians to master, they can provide a powerful reference for clinical decision-making.

Simplifying Tumor Volume Estimation from Linear Dimensions for Intra-Cranial Lesions Treated with Stereotactic Radiosurgery

Aims:

This study aims to derive simple yet robust formula(s) for the calculation of cranial tumor volume using linear tumor dimensions in anterioposterior (AP), mediolateral (ML) and craniocaudal (CC) directions and also propose a reproducible methodology for tumor dimension measurements.

Materials and Methods:

Magnetic resonance images (MRI) of 337 patients planned for Gammaknife Stereotactic Radiosurgery for different types of brain tumors were analyzed using Leksell Gamma Plan (LGP) software. Tumor volume in three dimensional was outlined and maximum tumor diameters were measured in three orthogonal directions AP, ML, and CC on the MRI. Formulas were derived to calculate tumor volume from AP, ML, and CC diameters using linear regression technique. An agreement between the calculated volume and standard volume observed from LGP software was determined using Bland Altman (B-A) plot. A comparison was made between the volume calculated using traditionally used formula of ellipsoid, standard volume obtained from LGP software and volume calculated from formulas derived in the present study.

Results:

The tumors were divided into two categories based on their size for better volume prediction. The tumors having product of their diameters in the range 0–2.5cc were called “small tumors” and the formula proposed for their volume estimation (V = 1.513) × (AP × ML × CC) + 0.047 ) was found to predict the tumor volume with an average bias of 0.0005cc. For “large tumors,” having product of diameters in the range 2.5–36cc, the proposed formula (V = 0.444 × (AP × ML × CC) + 0.339 ) predicted the tumor volume with an average bias of 0.007cc.

Conclusions:

The two formulas proposed in the study are more accurate as compared to the commonly used formula that considers the tumors as ellipsoids. The methodology proposed in the study for measurement of linear tumor dimensions is simple and reproducible.

Evolving Role of Non-Total Resection in Management of Acoustic Neuroma in the Gamma Knife Era

OBJECTIVE

To examine patients with residual tumor after vestibular schwannoma (VS) resection with focus on need for further therapy, including stereotactic radiosurgery (SRS) and revision surgery.

STUDY DESIGN AND SETTING

Retrospective review at two tertiary otology referral centers.

PATIENTS AND INTERVENTION

Patients undergoing primary surgery for VS from 2007 to 2017.

MAIN OUTCOME MEASURE

Degree of resection and need for further treatment.

RESULTS

Of 289 patients undergoing surgery, 38 (13.1%) underwent subtotal resections (<95% of tumor resected) and 77 (26.6%) underwent near-total resections (≥95% but <100%). Patients with any residual tumor had larger tumors preoperatively (mean estimated volume 6.3 cm versus 2.1 cm, p < 0.0005) but were otherwise clinically and demographically similar to the population as a whole. Further treatment (surgery or SRS) was needed in 4.6, 14.3, and 50.0% of patients after gross total, near-total, and subtotal resections, respectively (p < 0.0005). Patients undergoing additional therapy had larger residual tumors (median post- to preoperative estimated volume ratio 0.09 versus 0.01, p < 0.0005). Patients undergoing subtotal and near-total resections had poorer facial function at ultimate follow up than those undergoing gross total resections (p = 0.001), likely due to larger tumors and more difficult resections. Literature review revealed higher rates of gross total resection as well as facial palsy in the pre-SRS era.

CONCLUSION

Residual tumor following VS resection is more common today than in the pre-SRS era. Availability of SRS may encourage leaving residual tumor intraoperatively to preserve neural structures. Current surgical strategies decrease surgical morbidity but necessitate further treatment in over 10% of cases.

The Frontal Aslant Tract and Supplementary Motor Area Syndrome: Moving towards a Connectomic Initiation Axis

Simple Summary

Connectomics enables us to map whole brain networks that can be applied to operative neurosurgery to improve neuro-oncological outcomes. Damage to the superior frontal gyrus during frontal lobe surgery is thought to induce supplementary motor area (SMA) syndrome in patients. However, network-based modeling may provide a more accurate cortical model of SMA syndrome, including the Frontal Aslant Tract (FAT). The aim of our study was to retrospectively assess if surgical tractography with diffusion tensor imaging (DTI) decreases the likelihood of SMA syndrome. Compared to patients who underwent surgery preserving the SFG (n = 23), patients who had their FAT and SMA networks mapped through DTI and subsequently preserved were less likely to experience transient SMA syndrome. Preserving the FAT and SMA improves functional outcomes in patients following medial frontal glioma surgery and demonstrates how network-based approaches can improve surgical outcomes.

Abstract

Connectomics is the use of big data to map the brain’s neural infrastructure; employing such technology to improve surgical planning may improve neuro-oncological outcomes. Supplementary motor area (SMA) syndrome is a well-known complication of medial frontal lobe surgery. The ‘localizationist’ view posits that damage to the posteromedial bank of the superior frontal gyrus (SFG) is the basis of SMA syndrome. However, surgical experience within the frontal lobe suggests that this is not entirely true. In a study on n = 45 patients undergoing frontal lobe glioma surgery, we sought to determine if a ‘connectomic’ or network-based approach can decrease the likelihood of SMA syndrome. The control group (n = 23) underwent surgery avoiding the posterior bank of the SFG while the treatment group (n = 22) underwent mapping of the SMA network and Frontal Aslant Tract (FAT) using network analysis and DTI tractography. Patient outcomes were assessed post operatively and in subsequent follow-ups. Fewer patients (8.3%) in the treatment group experienced transient SMA syndrome compared to the control group (47%) (p = 0.003). There was no statistically significant difference found between the occurrence of permanent SMA syndrome between control and treatment groups. We demonstrate how utilizing tractography and a network-based approach decreases the likelihood of transient SMA syndrome during medial frontal glioma surgery. We found that not transecting the FAT and the SMA system improved outcomes which may be important for functional outcomes and patient quality of life.

Navigated transcranial magnetic stimulation following awake craniotomy for resection of glioma: Description of two cases

Background

Although transcranial magnetic stimulation (TMS) has been indicated as a potential therapy for several neurologic conditions, there is little known regarding its use during the postoperative rehabilitation period in patients with brain tumors. Furthermore, seizures, a common presentation in these patients, are regarded as a major contraindication for TMS therapy.

Case Description

We demonstrate that postoperative continuous theta burst stimulation (cTBS), a patterned form of repetitive TMS, was safely tolerated in addition to current neurorehabilitation techniques in two brain tumor patients, including one patient with a history of tumor-related epilepsy. We administered navigated 5 Hz cTBS to two patients within 48 h following awake craniotomy for tumor resection. Active motor thresholds were measured in both patients before TBS administration to determine stimulus intensity. We used resting-state fMRI to identify likely damaged networks based on postoperative deficits. This aided in TMS planning and allowed deficit targeted therapy contralateral to the lesioned network node. Both patients tolerated TBS therapy well and had no adverse effects, including posttreatment seizures, despite one patient having a history of tumor-related epilepsy.

Conclusion

TBS may be safe in the immediate postoperative period for patients following brain tumor resection. Additional studies are needed to quantify the efficacy of TMS in improving neurologic deficits following tumor resection.

Dural Ectasia in Neurofibromatosis 1: Case Series, Management, and Review

BACKGROUND

The natural history and management of dural ectasia in Neurofibromatosis 1 (NF1) is still largely unknown. Dural ectasias are one of the common clinical manifestations of NF1; however, the treatment options for dural ectasias remain unstudied.

OBJECTIVE

To investigate the natural history, diagnosis, management, and outcome of the largest case series of patients with NF1-associated dural ectasia to date.

METHODS

Records from our NF1 clinic were reviewed to identify NF1 patients with computed tomography or magnetic resonance imaging evidence of dural ectasia(s) to determine their clinical course. Demographics, symptoms, radiographic and histopathologic findings, treatment, and clinical course were assessed.

RESULTS

Thirty-four of 37 patients were managed without surgery. Of the 18 initially asymptomatic patients, 5 (27.8%) progressed to symptoms attributable to a dural ectasia (onset of 2.7% per patient-year). Three patients required surgical intervention because of extraspinal mass effect. All 3 initially improved but had symptom recurrence within 2 yr. Reoperation involved shunt placement for cerebrospinal fluid (CSF) diversion. On imaging review, 26 (76.5%) of the nonsurgical patients harbored an associated nearby plexiform neurofibroma. Pathology of one surgical case revealed dural infiltration by diffuse neurofibroma.

CONCLUSION

Using the largest NF1-associated dural ectasia group to date, we report the first symptom-onset rate for nonsurgical patients. In the few cases requiring surgery for decompression, primary resection, and patching of ectasias failed, subsequently requiring CSF shunting. We demonstrate imaging evidence of nearby plexiform neurofibroma in a majority of cases, which, when combined with histopathology, provides a novel explanation for the formation of dural ectasias.

Nonoptic pathway tumors in children with neurofibromatosis type 1

OBJECTIVE

To define the radiologic features and natural history of nonoptic pathway tumors (non-OPTs) in children with neurofibromatosis type 1 (NF1).

METHODS

We performed a retrospective cross-sectional analysis of 64 children with NF1 harboring 100 probable non-OPTs. Age at diagnosis, sex, tumor location, number of tumors, symptomology, concurrent OPT, radiographic progression (defined as qualitative and quantitative increases in size), and treatment were assessed. Tumor volumes were measured from initial presentation until treatment or end of disease progression.

RESULTS

Sixty-three percent of probable non-OPTs progressed over time, where radiographic progression was concomitantly associated with clinical progression. Fifty-two percent of patients had incidentally identified probable non-OPTs. Twenty-five percent of patients were symptomatic at initial diagnosis, all of whom harbored tumors that grew on subsequent scans and required tumor-directed therapy. There were no clinical differences between probable non-OPTs localized to the brainstem vs other locations with respect to age, sex, concurrent optic pathway glioma, symptomology, and treatment. The average time from diagnosis to stabilization or decrease in tumor size was 2.34 years (SD, 2.15 years). Nineteen biopsied lesions were all histopathologically confirmed as tumor. Six children (9%) had deep extensive tumors, who presented earlier (mean age at diagnosis, 3.88 years), required multiple treatments, and had a shorter mean progression-free survival (48 months).

CONCLUSIONS

Over half of children with NF1 in this study developed probable non-OPTs, the majority of which were clinically and radiographically progressive. While brainstem and nonbrainstem gliomas share similar clinical features and natural history, deep extensive tumors comprise a distinct aggressive group of tumors that warrant close attention.

Audiologic Natural History of Small Volume Cochleovestibular Schwannomas in Neurofibromatosis Type 2

OBJECTIVE

To characterize the audiometric natural progression in patient-ears with small volume (<1,000 mm), treatment-naïve cochleovestibular schwannomas (CVSs) in Neurofibromatosis Type 2 (NF2).

STUDY DESIGN

Prospective, longitudinal cohort study.

SETTING

Quaternary medical research institute.

PATIENTS

One hundred eleven ears in 71 NF2 patients with small, treatment-naïve CVSs observed from July 2006 to July 2016.

INTERVENTION

Serial audiometric testing, including pure tone audiometry, speech audiometry, and magnetic resonance imaging (MRI).

OUTCOME MEASURES

Four-frequency pure tone average (4f-PTA) of 0.5, 1, 2, and 4 kHz and word recognition score (WRS) were recorded. Their changes were compared with MRI changes in CVS volume over time. Times to significant hearing loss (10 dB loss in 4f-PTA) and WRS based on 95% critical difference were measured.

RESULTS

Linear regression analysis showed a significant correlation with baseline hearing level (4f-PTA) and internal auditory canal (IAC) tumor volume to annual hearing decrease rate (AHDR) (p = 0.003, p = 0.0004). Hearing level at baseline and tumor volume correlate with AHDR while tumor volume growth rate does not. Two-way analysis of variance found significant differences in AHDR, risk of significant hearing loss, and risk of critical difference in WRS based on baseline hearing level (abnormal or normal) and IAC tumor volume (greater or less than 200 mm).

CONCLUSION

Subjects with normal baseline hearing and small IAC tumor component had a low AHDR and low risk of significant hearing loss and may warrant conservative management while the presence of baseline hearing loss and large IAC volume resulted in higher ADHR and greater risk for further hearing loss and may benefit from early treatment interventions.

Audiological Outcomes in Growing Vestibular Schwannomas Managed Either Conservatively, or With Stereotactic Radiosurgery

OBJECTIVE

Recent studies have suggested good hearing preservation following stereotactic radiosurgery (STRS) in patients with vestibular schwannomas (VS). This study aims to assess audiological outcomes in patients with growing VS treated either with STRS, or managed conservatively.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary referral center.

PATIENTS

Out of 540 patients with VS, 69 patients with growing VS fulfilled the inclusion criteria; 24 treated conservatively and 45 with STRS. VS were considered growing if demonstrating more than 15% tumor volume increase during 1 year of watchful waiting.

INTERVENTION

American Association of Otolaryngology-Head and Neck Surgery (AAOHNS) hearing threshold (dB averaged over 500-3000 Hz) deterioration and Gardner-Robertson class deterioration over time were used as the primary outcome measures. Rate of progression to loss of functional hearing (Gardner-Robertson class I-II) was also determined between cohorts.

RESULTS

Mean follow-up was similar between treatment cohorts (STRS = 69.6 mo, conservative management = 71.7 mo). There was no significant difference in AAOHNS deterioration (t = 1.05, df = 53, p = 0.301) or Gardner-Robertson deterioration (χ = 0.47, df = 1, p = 0.492) between cohorts. Furthermore, rate of progression to loss of functional hearing was similar between cohorts (Hazard ratio = 0.704, 95% CI 0.287-1.728, p = 0.44). In STRS patients, AAOHNS deterioration was greater in those with lower AAOHNS thresholds at diagnosis (t = -2.683, df = 28, p = 0.0121). Similarly, Gardner-Robertson deterioration was significantly more likely in STRS patients with functional hearing (Gardner-Robertson class I-II) (Adjusted odds ratio = 32.14, 95% CI 3.15-328, p = 0.0034).

CONCLUSIONS

STRS results in similar audiological outcomes compared with patients managed conservatively; Consequently, STRS given to patients with VS to preserve hearing is not justified. In contrast to recent studies, patients with preserved hearing at diagnosis have significantly greater audiological deterioration when undergoing STRS.

Management of Giant Pituitary Adenomas: Role and Outcome of the Endoscopic Endonasal Surgical Approach

Giant adenomas represent a significant surgical challenge. Although traditionally several transcranial and transsphenoidal microscopic approaches have had a central role in their management, in the last 2 decades here have been increasing reports of the endoscopic endonasal approach for giant adenomas, citing its improved resection rates and lower complication profile. However, its role as the preferred approach has not been fully established and there is currently a paucity of evidence-based recommendations available in the literature. This article reviews the current literature and attempts to define the role and outcomes of the endoscopic endonasal surgical approach for giant pituitary adenomas.

Management of hydrocephalus after resection of posterior fossa lesions in pediatric and adult patients-predictors for development of hydrocephalus

The surgical management of hydrocephalus in patients with posterior fossa lesions (PFL) is critical for optimal patient outcome(s). Accordingly, it is prudent to identify patients in need of aggressive surgical intervention (i.e., ventriculoperitoneal [VP] shunting). To analyze prevalence of, and risk factors associated with, the development of post-operative hydrocephalus in both pediatrics and adults. A retrospective institutional analysis and review of patient records in those who had undergone PFL surgery was performed. In so doing, the authors identified patients that went on to develop post-operative hydrocephalus. The study included pediatric and adult patients treated between 2009 and 2017. Fifteen of 40 pediatric (37.5%) and 18 of 262 adult (6.9%) patients developed hydrocephalus after PFL surgery. The most common tumor entity in pediatrics was medulloblastoma (34%), astrocytoma (24.4%), and pilocytic astrocytoma (22%), whereas in adults, metastasis (29.5%), meningioma (22%), and acoustic neuroma (17.8%) were most common. Young age ≤ 2 years, medulloblastoma (OR 13.9), and brain stem compression (OR 5.4) were confirmed as independent predictors for hydrocephalus in pediatrics and pilocytic astrocytoma (OR 15.4) and pre-operative hydrocephalus (OR 3.6) in adults, respectively. All patients received VP shunts for hydrocephalus management and the mean follow-up was 29.5 months in pediatrics vs 19.2 months in adults. Overall complication rates related to VP shunts were 33.3% in pediatrics and 16.7% in adults, respectively. Shunt dependency and associated complications in pediatrics were noted to be higher than in adults. Given the identification of predictors for hydrocephalus, it is authors' contention that certain patients with those predictors may ultimately benefit from an alternative treatment regimen (e.g., pre-operative interventions) prior to PFT surgery.

Skull Base Enchondroma and Chondrosarcoma in Ollier Disease and Maffucci Syndrome

BACKGROUND

Maffucci syndrome (MS) and Ollier disease (OD) are rare diseases characterized by multiple benign enchondromas. The incidence of skull base (SB) enchondromas and the risk of malignant transformation remain unknown. Most SB lesions are asymptomatic, and surgical resection carries significant morbidity. Observation may be a reasonable strategy. We report our experience with observation of probable SB enchondromas in MS/OD patients.

METHODS

Retrospective review of OD/MS patients with cranial imaging between 1995 and 2018 at 1 institution.

RESULTS

14 patients were included: 3 with MS (21.4%) and 11 with OD (78.6%). The median age was 28 years (range, 11-74 years) and 57.1% were female. Extracranial chondrosarcoma was reported in 3 (21.4%) patients. Seven (50%) patients with SB enchondroma or chondrosarcoma were identified on initial imaging. In patients with SB lesions, the indications for imaging were headache (n=3), seizure (n=1), and diplopia (n=1); 2 cases were incidental findings. The most commonly involved structures were petroclival fissure (86%) and clivus (71%). Treatment included observation (6/7) and resection (1/7). Follow-up imaging was available for all SB lesions, with a mean interval of 50.7 months (range, 5-225 months) and was negative for progression in all patients.

CONCLUSIONS

Primary SB lesions in OD/MS patients frequently present in the petroclival junction. Cranial screening and close observation should be considered in MS/OD patients, given the increased risk of intra-axial intracranial tumors, de novo chondrosarcomas, or malignant degeneration of previously known lesions. In asymptomatic patients, observation appears to be a safe strategy in this cohort. Further case accumulation and follow-up are required to better understand the long-term outcomes.

Assessing the volume of large cerebral arteriovenous malformations: Can the ABC/2 formula reliably predict true volume?

BACKGROUND

Outcomes of stereotactic radiosurgery in the treatment of cerebral arteriovenous malformations (AVMs) are volume-dependent. The ability to estimate AVM volume has significant value in guiding AVM management.

OBJECTIVE

To determine whether AVM volume measurement calculated from the ABC/2 formula is accurate compared to volume calculated by a computer-assisted planimetric method for large AVMs.

METHODS

Retrospective review of 42 intracranial AVMs >3 cm in diameter that underwent treatment with dose-staged hypofractionated stereotactic radiotherapy (HSRT) from 2001 to 2018. Two raters independently measured pre- and post-HSRT volumes using both the ABC/2 formula and computer-assisted planimetry in a blinded fashion. Inter-rater reliability was assessed by calculation of intra-class correlation coefficient (ICC). Absolute volumes and percent volume change following HSRT as determined using the two methods were compared using paired t-tests, linear regression, and Bland-Altman plot analyses.

RESULTS

The ICC between the 2 raters for planimetric and ABC/2 volumes was 0.859 and 0.799, respectively. ABC/2 volumes, 26.1 ± 26.6 cm³, were statistically smaller than planimetric volumes, 28.6 ± 27.1 cm³ (P = .008). Despite differences, the two methods were highly correlated (R² = 0.904, linear regression). The percent volume change following HSRT was significantly greater with the ABC/2 method than compared to planimetry (P = .009).

CONCLUSION

The ABC/2 and planimetric methods are reproducible for measuring cerebral AVM volumes. Although the ABC/2 method of volume estimation underestimates planimetric AVM volume, the high correlation between the two suggests utility of the ABC/2 method if one understands its limits, particularly with respect to estimating change in AVM volume after treatment.

Surgical Resection and Adjuvant Radiation Therapy in the Treatment of Skull Base Chordomas

OBJECTIVE

Chordomas are rare tumors of notochordal origin that are known to be locally aggressive and are often treated with surgical resection followed by adjuvant radiation therapy (RT). The accepted standard of treatment for chordomas of the mobile spine, which includes en-bloc resection with wide margins, cannot be easily applied to the chordomas of the skull base because of their proximity to critical neurovascular structures. We describe our experience with the role of surgery and adjuvant RT in the treatment of chordomas over 16 years.

METHODS

We performed a retrospective chart review on patients with diagnoses of clival chordoma between the years 2000 and 2015 at Northwestern Memorial Hospital. We reviewed presenting symptoms, tumor location and size, extent of resection, complications, recurrence, adjuvant treatment, and follow-up duration.

RESULTS

A total of 20 patients underwent 32 surgeries. Of the 20 initial surgeries, 80% underwent gross total resection, and 20% had subtotal resection. The mean follow-up time was 60.75 months. Mean tumor volume was 23.07 cm³. Most common presenting signs and symptoms were headaches (70%), cranial nerve palsies (45%), and diplopia (55%). Diplopia was defined as complaints of double vision without any objective evidence of a cranial nerve palsy. Median time to progression was 57 months, and median overall survival was 136 months. Initial tumor volume and the need for a second dose of RT either as sole or as adjuvant treatment of a recurrence had a statistically significant effect on progression-free survival (P = 0.009, 0.009). None of the factors studied had a statistically significant effect on overall survival.

CONCLUSIONS

The treatment of chordomas remain challenging and requires multimodal treatment strategies spanning different specialties. Initial tumor size and need for second dose of RT for recurrence appear to play a significant role in progression-free survival. Adjuvant RT after gross total resection may play a role in improved progression-free and overall survival in patients with clival chordomas.

Calculating the Tumor Volumes in Vestibular Schwannomas: Are the ABC/2 and Volumetric Methods Comparable?

PURPOSE

To assess the efficacy of the ABC/2 method for calculating the volume of vestibular schwannomas as compared with 3-D planimetric method.

STUDY DESIGN

Retrospective.

METHODS

Fifty eight cases of pathologically confirmed sporadic vestibular schwannomas (VS) were analyzed. Tumors volumes were calculated for each tumor twice, once through semiautomated 3-D volumetric method and subsequently through ABC/2 (AP × ML × CC/2) methodology after calculating the maximal tumor dimensions in anteroposterior (AP), coronal (ML), and craniocaudal (CC) dimensions. Tumor volumes were initially correlated as a group and subsequently by dividing them into three groups using the Hannover classification.

RESULTS

The two methodologies were highly correlated when tumors were analyzed as a group (rho = 0.913, p < 0.0001). In the sub-group analysis, tumor volumes were again strongly correlated for larger tumors (rho = 0.918, p < 0.0001) but the correlation progressively reduced as tumor volumes decreased.

CONCLUSION

Given the ease and universal accessibility of linear measurement applications, the ABC/2 methodology is a robust substitute for calculating tumor volumes, especially for larger tumors.

Vestibular schwannomas: Accuracy of tumor volume estimated by ice cream cone formula using thin-sliced MR images

PURPOSE

We estimated the volume of vestibular schwannomas by an ice cream cone formula using thin-sliced magnetic resonance images (MRI) and compared the estimation accuracy among different estimating formulas and between different models.

METHODS

The study was approved by a local institutional review board. A total of 100 patients with vestibular schwannomas examined by MRI between January 2011 and November 2015 were enrolled retrospectively. Informed consent was waived. Volumes of vestibular schwannomas were estimated by cuboidal, ellipsoidal, and spherical formulas based on a one-component model, and cuboidal, ellipsoidal, Linskey's, and ice cream cone formulas based on a two-component model. The estimated volumes were compared to the volumes measured by planimetry. Intraobserver reproducibility and interobserver agreement was tested. Estimation error, including absolute percentage error (APE) and percentage error (PE), was calculated. Statistical analysis included intraclass correlation coefficient (ICC), linear regression analysis, one-way analysis of variance, and paired t-tests with P < 0.05 considered statistically significant.

RESULTS

Overall tumor size was 4.80 ± 6.8 mL (mean ±standard deviation). All ICCs were no less than 0.992, suggestive of high intraobserver reproducibility and high interobserver agreement. Cuboidal formulas significantly overestimated the tumor volume by a factor of 1.9 to 2.4 (P ≤ 0.001). The one-component ellipsoidal and spherical formulas overestimated the tumor volume with an APE of 20.3% and 29.2%, respectively. The two-component ice cream cone method, and ellipsoidal and Linskey's formulas significantly reduced the APE to 11.0%, 10.1%, and 12.5%, respectively (all P < 0.001).

CONCLUSION

The ice cream cone method and other two-component formulas including the ellipsoidal and Linskey's formulas allow for estimation of vestibular schwannoma volume more accurately than all one-component formulas.

Three-Dimensional Volumetric Segmentation of Pituitary Tumors: Assessment of Inter-rater Agreement and Comparison with Conventional Geometric Equations

Background  The assessment of pituitary tumor (PT) volume is important in the treatment and follow-up of patients with PT. Previously, PT volume estimation has been performed by conventional geometric equations (CGE) such as abc/2 (simplified ellipsoid volume equation) and 4πr ³ /3 (sphere), both presuming a symmetric tumor shape, which occurs uncommonly in patients with PT. In contrast, three-dimensional (3D) voxel-based software segmentation takes the irregular and asymmetric shapes that PTs often possess into account and might be a more accurate method for PT volume segmentation. The purpose of this study is twofold. (1) To compare 3D segmentation with CGE for PT volume estimation. (2) To assess inter-rater reliability in 3D segmentation of PTs. Methods  Nineteen high-resolution (1mm slice thickness) T1-weighted MRI examinations of patients with PT were independently analyzed and manually segmented, using the software ITK-SNAP, by two certified neuroradiologists. Concurrently, the volumes of the PTs were estimated with abc/2 and 4πr ³ /3 by a clinician, and the results were compared with the corresponding segmented volumes. Results  There was a significant decrease in PT volume attained from the segmentations compared with the calculations made with abc/2 ( p  < 0.001, mean volume 18% higher than segmentation) and 4πr ³ /3 ( p  < 0.001, mean volume 28% higher than segmentation). The intraclass correlation coefficient (ICC) for the two sets of segmented PTs was 0.99. Conclusion  CGE ( abc/2 and 4πr ³ /3 ) significantly overestimates PT volume compared with 3D volumetric segmentation. The inter-rater agreement on manual 3D volumetric software segmentation is excellent.

Endoscopic Approach to Clival Chordomas: The Northwestern Experience

INTRODUCTION

Chordomas are rare primary bone tumors with a low-grade histology but an aggressive clinical behavior characterized by local invasion and recurrence. When occurring in the skull base, their treatment is limited by proximity to critical neurovascular structures. Open surgical approaches can carry high morbidity, making the development of alternative approaches desirable. We describe our experience with endoscopic endonasal approaches to clival chordomas over 13 years.

METHODS

We performed a retrospective chart review of patients diagnosed with clival chordomas and treated with an endoscopic endonasal approach between 2003 and 2015 at Northwestern Memorial Hospital. We reviewed presenting symptoms, tumor location and size, extent of resection, complications, recurrence, adjuvant treatment, retreatment, and follow-up duration.

RESULTS

A total of 23 charts were reviewed, with 17 included in our final review. Mean age was approximately 48 years. The most common presenting symptom was diplopia present in 70.6% of patients. Mean tumor volume was 20.2 cm³. Gross total resection was achieved in 52.9% of patients. With a mean follow-up period of 63.4 months, 5 patients had a recurrence. The most common complication was cerebrospinal fluid (CSF) leak, which was noted in 6 patients. Tumor volume was significantly higher in patients with CSF leak. No correlation between intradural extension and postoperative CSF leak was noted.

CONCLUSIONS

Clival chordoma are challenging entities to treat. The best outcomes are achieved with gross total resection followed by adjuvant radiotherapy treatment. We show that the endonasal endoscopic corridor is a viable alternative approach to these lesions.

Vestibular Schwannomas: Do Linear and Volumetric Parameters on MRI Correlate With Hearing Loss?

PURPOSE

To determine if two-dimensional and volumetric imaging parameters in vestibular schwannomas (VS) correlate with hearing loss at presentation.

STUDY DESIGN

Retrospective.

METHODS

Forty-one cases of pathologically confirmed sporadic VS were analyzed. Maximal tumor dimensions in anteroposterior (AP), coronal (ML), and craniocaudal (CC) dimensions were obtained along with tumor-fundus distance and internal auditory canal (IAC) porus diameters. Volumetric analysis was done on 37 cases. Tumors volumes were calculated through both 3-D volumetric and ABC/2 [AP × ML × CC/2] methodology. With the 3-D method, total tumor volume (TTV), and cerebellopontine angle (CPA) tumor volume were separately calculated and IAC volumes obtained by subtracting CPA tumor volumes from TTV. Pure tone average (PTA) and speech discrimination scores (SDS) were correlated with tumor dimensions.

RESULTS

Non-volumetric analysis was performed on 41 tumors. The AP and ML dimensions correlated with both PTA and SDS (p < 0.05). No significant correlations were seen between hearing loss and tumor-fundus distance or porus diameters. The tumor volume calculated through ABC/2 methodology correlated with PTA and SDS (p < 0.05). The 3-D TTV and CPA volumes only correlated with PTA. IAC tumor volumes did not correlate with hearing loss.

CONCLUSION

Maximal AP and ML dimensions are the only non-volumetric variables, which significantly correlate with hearing loss. Tumor volume calculated through ABC/2 method significantly correlates with hearing impairment while the 3-D TTV and CPA tumor volumes only correlated significantly with PTA scores but not SDS scores.

Simultaneous Resection of Multiple Metastatic Brain Tumors with Multiple Keyhole Craniotomies

BACKGROUND

The proper management of symptomatic patients with 2 or more brain metastases is not entirely clear, and the surgical outcomes of these patients undergoing multiple simultaneous craniotomies have not been well described. In this article, we describe patient outcomes after simultaneously resecting metastatic lesions through multiple keyhole craniotomies.

METHODS

We conducted a retrospective review of data obtained for all patients undergoing resection of multiple brain metastases in one operation between 2014 and 2016. We describe a technique for resecting multiple metastatic lesions and share the patient outcomes of this operation.

RESULTS

Twenty patients with 46 tumor resections were included in the study. The primary site of metastases for the majority of patients was lung, followed by melanoma, renal, breast, colon, and testes. Nine of 20 (45%) patients had 2 preoperative intracranial lesions, and 11 (55%) had three or more. Karnofsky performance scales were calculated for 14 patients: postoperatively 10 of 14 (71%) scores improved, 2 of 14 (14%) worsened, and 2 of 14 (14%) remained unchanged. After surgery, 9 of 14 (64%) patients were weaned off steroids by 2-month follow-up. The overall median survival time from date of surgery was 10.8 months.

CONCLUSIONS

We present patient outcomes after simultaneously resecting metastatic brain tumors through multiple keyhole craniotomies in symptomatic patients. Our results suggest comparable outcomes and similar surgical risk compared with those undergoing resection of a single brain metastasis. Resection of multiple brain metastases may improve Karnofsky Performance Scale scores in the early postoperative period and allow patients to be weaned from steroids.

Predicting the necessity of anterior communicating artery division in the bifrontal basal interhemispheric approach

Background

The anterior communicating artery (ACoA) often limits surgical exposure in the anterior interhemispheric approach. Although division of the ACoA has been proposed occasionally, it is rarely practiced, and criteria for such a surgical maneuver remain unknown. Our purpose was to identify key factors that allow for predicting the necessity of controlled ACoA division in the bifrontal basal interhemispheric approach.

Method

Twenty-two consecutive patients who underwent surgery via the bifrontal basal interhemispheric approach for removal of various pathologic brain lesions were examined. First, tumors were dichotomized into central and lateral lesions. Next, three tumor parameters were compared between cases with and without ACoA division in each, the central and lateral lesion groups, respectively: tumor volume, tumor depth (defined as distance between the ACoA and posterior tumor margin) and tumor laterality angle (defined as the geometric angle between the lateral tumor margin and sagittal midline).

Results

Tumor volume was not related in a statistically significant manner to ACoA division in both the central (P = 0.06) and lateral (P = 0.13) lesion groups, respectively. However, tumor depth was significantly correlated with ACoA division in the central lesion group (P = 0.01), whereas in the lateral lesion group, the tumor laterality angle showed a significant correlation with ACoA division (P = 0.04).

Conclusions

Our results suggest that controlled ACoA division may be required in central lesions with a depth of 38 mm or more and in lateral lesions with an angle of 23 degrees or more as defined in this study. Two key factors were thus identified that may predict the necessity of controlled ACoA division before surgery.

Reliability of the Size Evaluation Method for Meningiomas: Maximum Diameter, ABC/2 Formula, and Planimetry Method

BACKGROUND

To evaluate the accuracy of tumor size by maximum diameter, ABC/2 formula, and planimetry method using thick-slice and thin-slice magnetic resonance imaging (MRI).

METHODS

Maximum diameter and tumor volume calculated using ABC/2 formula (V1) and planimetry method with thick-slice MRI (V2) and thin-slice MRI (V3) were examined in 83 meningiomas. Form factor (FF) analysis was performed to assess irregularity of the tumor. V3 values were considered as real tumor volumes. The accuracy of V1 and V2 was evaluated using ratio and difference from V3. Meningiomas were categorized by tumor locations: skull base (anterior, middle, and posterior) and non-skull base (calvaria and other sites).

RESULTS

Correlation between maximum diameter and V3 was statistically significant (r = 0.91), but the error was significant in tumors with longer maximum diameters. Correlation between V1 and V3 was significant (r = 0.97). However, V1 tended to be larger in middle skull base meningiomas or in tumors with low FF values (R² = 0.21). V2 represented relatively accurate volumes in both groups except in the case of small meningiomas. When tumors were demonstrated within 3 fractions on thick-slice MRI, the ratio of V2 to V3 showed significant variability.

CONCLUSIONS

Using the ABC/2 formula, the volume of meningiomas in the middle skull base or meningiomas with low FF value might be calculated larger than the real tumor volume. The planimetry method with thick-slice MRI demonstrated relatively accurate volumes if the tumor was fractionated in >4 slices.

Clinical and Radiographic Factors Predicting Hearing Preservation Rates in Large Vestibular Schwannomas

Objectives Postoperative hearing preservation rates for patients with large vestibular schwannomas range from 0 to 43%. The clinical and radiographic factors predicting hearing preservation in smaller vestibular schwannomas are well described; however, their importance in larger tumors is unclear. We investigated factors predicting hearing preservation in large vestibular schwannomas. Design Retrospective review. Setting Quaternary care academic center. Participants A total of 85 patients with unilateral vestibular schwannomas > 3 cm underwent retrosigmoid resections. Main Outcomes Measures Preoperative and postoperative serviceable hearing rates. Methods Clinical and radiographic data including preoperative and postoperative audiograms, preoperative symptoms, magnetic resonance imaging features, and postoperative facial weakness were analyzed. Results Hearing was preserved in 41% of patients (17 of 42) with preoperative serviceable hearing. Hypertension and diabetes increased the likelihood of preoperative hearing loss. Preoperative tinnitus predicted a lower likelihood of hearing preservation. No radiographic factors predicted hearing preservation; however, larger tumor size, smaller fourth ventricular width, and the presence of a cerebrospinal fluid cleft surrounding the tumor predicted postoperative facial weakness. Conclusion Systemic comorbidities may influence hearing loss preoperatively in patients with large vestibular schwannomas. The absence of tinnitus may reflect hearing reserve and propensity for hearing preservation. Preoperative radiographic features did not predict hearing preservation despite some associations with postoperative facial weakness.

Current indications for the surgical treatment of prolactinomas

The purpose of this study was to examine the current indications for transsphenoidal surgery in the prolactinoma patient population, and to determine the outcomes of patients who undergo such operations. Transsphenoidal surgery may be indicated in prolactinoma patients who are resistant and/or intolerant to dopamine agonist (DA) therapy. We performed a retrospective review of the medical records of prolactinoma patients over a 6 year period (April 2008 to April 2014) at a large volume academic center. The median follow-up time was 12.0 months (range: 3-69). All patients who were included in the study (n=66) were treated with DA therapy and subsequently underwent an endonasal transsphenoidal operation. Of the 66 patients, 44 were women (mean age 34.2 years) and 22 were men (mean 41.7 years). There were 29 (43.9%) intolerant patients and 29 (43.9%) resistant patients. Postoperatively, 18 intolerant patients (66.7%) had normalized prolactin levels without the need for DA therapy, and five (17.2%) required DA to normalize their prolactin levels (p=0.02). Six patients (20.6%) had persistently elevated prolactin levels but were no longer receiving DA treatment (p<0.001). Postoperatively, 10 resistant patients (35.7%) had normal prolactin levels without DA therapy, and seven patients (25%) were treated with DA therapy to normalize their prolactin levels (p=0.22). Eight patients (28.6%) had supraphysiologic prolactin levels but were no longer taking a DA (p<0.001). Three patients (10.7%) were hyperprolactinemic, despite postoperative treatment with DA (p<0.001). After an appropriate treatment interval with multiple DA, radiographic follow-up, and careful clinical evaluation, prolactinoma patients can be offered surgery as an effective therapeutic option.

High-resolution(18)F-fluorodeoxyglucose positron emission tomography and magnetic resonance imaging for pituitary adenoma detection in Cushing disease

OBJECT High-resolution PET (hrPET) performed using a high-resolution research tomograph is reported as having a resolution of 2 mm and could be used to detect corticotroph adenomas through uptake of(18)F-fluorodeoxyglucose ((18)F-FDG). To determine the sensitivity of this imaging modality, the authors compared(18)F-FDG hrPET and MRI detection of pituitary adenomas in Cushing disease (CD). METHODS Consecutive patients with CD who underwent preoperative(18)F-FDG hrPET and MRI (spin echo [SE] and spoiled gradient recalled [SPGR] sequences) were prospectively analyzed. Standardized uptake values (SUVs) were calculated from hrPET and were compared with MRI findings. Imaging findings were correlated to operative and histological findings. RESULTS Ten patients (7 females and 3 males) were included (mean age 30.8 ± 19.3 years; range 11-59 years). MRI revealed a pituitary adenoma in 4 patients (40% of patients) on SE and 7 patients (70%) on SPGR sequences.(18)F-FDG hrPET demonstrated increased(18)F-FDG uptake consistent with an adenoma in 4 patients (40%; adenoma size range 3-14 mm). Maximum SUV was significantly higher for(18)F-FDG hrPET-positive tumors (difference = 5.1, 95% CI 2.1-8.1; p = 0.004) than for(18)F-FDG hrPET-negative tumors.(18)F-FDG hrPET positivity was not associated with tumor volume (p = 0.2) or dural invasion (p = 0.5). Midnight and morning ACTH levels were associated with(18)F-FDG hrPET positivity (p = 0.01 and 0.04, respectively) and correlated with the maximum SUV (R = 0.9; p = 0.001) and average SUV (R = 0.8; p = 0.01). All(18)F-FDG hrPET-positive adenomas had a less than a 180% ACTH increase and(18)F-FDG hrPET-negative adenomas had a greater than 180% ACTH increase after CRH stimulation (p = 0.03). Three adenomas were detected on SPGR MRI sequences that were not detected by(18)F-FDG hrPET imaging. Two adenomas not detected on SE (but no adenomas not detected on SPGR) were detected on(18)F-FDG hrPET. CONCLUSIONS While(18)F-FDG hrPET imaging can detect small functioning corticotroph adenomas and is more sensitive than SE MRI, SPGR MRI is more sensitive than(18)F-FDG hrPET and SE MRI in the detection of CD-associated pituitary adenomas. Response to CRH stimulation can predict(18)F-FDG hrPET-positive adenomas in CD.