The 6 thalamic regions: surgical approaches to thalamic cavernous malformations, operative results, and clinical outcomes

Endoscopic Supracerebellar Infratentorial Transpineal Approach for Posterior-Medial Thalamic Lesions: Surgical Technique and Clinical Experience

BACKGROUND AND OBJECTIVES

Accessing lesions in the posterior-medial thalamus can be challenging because of their deep location and intricate neurovascular anatomy. This study aims to describe the techniques and feasibility of the endoscopic supracerebellar infratentorial transpineal approach for treating posterior-medial thalamus lesions.

METHODS

We reviewed and analyzed the clinical outcomes and endoscopic surgical experience of 11 patients with posterior-medial thalamic lesions. The first 4 cases used the endoscopic midline supracerebellar infratentorial transpineal approach, whereas the subsequent 7 cases used the endoscopic contralateral paramedian supracerebellar infratentorial transpineal approach. All cases involved the upward transposition of the pineal gland to access the posterior-medial thalamus. The extent of resection and the endoscopic techniques were the main focus of analysis. Neurological examinations and MRI/computed tomography follow-up were conducted for 3-12 months after surgery.

RESULTS

The pathology of the group included 6 gliomas, 1 cavernous malformation, 1 inflammation, 1 melanoma, and 2 hematomas. All 11 patients achieved gross total resection (6 patients, 54.5%) or subtotal resection (5 patients, 45.5%) with no new neurological deficits. Most patients (9 patients, 81.8%) experienced improvement in Karnofsky Performance Status after surgery. Postoperative hydrocephalus occurred in 2 patients (18.2%) and was relieved by endoscopic third ventriculostomy.

CONCLUSION

The endoscopic supracerebellar infratentorial transpineal approach is an effective approach for removing posterior-medial thalamic lesions that require access through the third ventricle surfaces of the thalamus. The endoscopic contralateral paramedian supracerebellar infratentorial transpineal approach provides a more superior and lateral view of the posterior-medial thalamic lesions.

Microsurgical removal of supratentorial and cerebellar cavernous malformations: what has changed? A single institution experience

BACKGROUND

Features associated with a safe surgical resection of cerebral cavernous malformations (CMs) are still not clear and what is needed to achieve this target has not been defined yet.

METHODS

Clinical presentation, radiological features and anatomical locations were assessed for patients operated on from January 2008 to January 2018 for supratentorial and cerebellar cavernomas. Supratentorial CMs were divided into 3 subgroups (non-critical vs. superficial critical vs. deep critical). The clinical outcome was assessed through modified Rankin Scale (mRS) and was divided into favorable (mRS 0-1) and unfavorable (mRS ≥ 2). Post-operative epilepsy was classified according to the Maraire Scale.

RESULTS

A total of 144 were considered eligible for the current study. At 6 months follow-up the clinical outcome was excellent for patients with cerebellar or lobar CMs in non-critical areas (mRS ≤ 1: 91.1 %) and for patients with superficial CMs in critical areas (mRS ≤ 1: 92.3 %). Patients with deep-seated suprantentorial CMs showed a favorable outcome in 76.9 %. As for epilepsy 58.5 % of patients presenting with a history of epilepsy were free from seizures and without therapy (Maraire grade I) at last follow-up (mean 3.9 years) and an additional 41.5 % had complete control of seizures with therapy (Maraire grade II).

CONCLUSIONS

Surgery is safe in the management of CMs in non-critical but also in critical supratentorial locations, with a caveat for deep structures such as the insula, the basal ganglia and the thalamus/hypothalamus.

An endoscopic-assisted contralateral paramedian supracerebellar infratentorial approach in the treatment of thalamic hemorrhage with hematoma extension into the brainstem: a case report

Objective

Thalamic hemorrhage (TH) with hematoma extension into the brainstem can lead to poor outcomes. In this study, we discuss the feasibility of the endoscopic-assisted contralateral paramedian supracerebellar infratentorial (SCIT) approach as a therapeutic method for treating such patients.

Case presentation

A patient suffered from a sudden loss of consciousness and right limb weakness, and a CT scan indicated TH with hematoma extension into the brainstem. She consented to undergo surgery by the endoscopic-assisted contralateral paramedian SCIT approach.

Results

Now, the patient can open her eyes on her own and move her left arm in response to commands.

Conclusion

The endoscopic-assisted contralateral paramedian SCIT approach may be a viable therapeutic method for treating TH patients with hematoma extension into the brainstem.

The anterior perforated substance (APS) revisited: Commented anatomical and imagenological views

INTRODUCTION

Since 2002, when we published our article about the anterior perforated substance (APS), the knowledge about the region has grown enormously.

OBJECTIVE

To make a better description of the anatomy of the zone with new dissection material added to the previous, to sustain the anatomical analysis of the MRI employing the SPACE sequence, interacting with our imagenology colleagues. Especially, we aim to identify and topographically localize by MRI the principal structures in APS-substantia innominata (SI).

METHOD

The presentation follows various steps: (1) location and boundaries of the zone and its neighboring areas; (2) schematic description of the region with simple outlines; (3) cursory revision of the SI and its three systems; (4) serial images of the dissections of the zone and its vessels, illustrated and completed when possible, by MRI images of a voluntary experimental subject (ES).

RESULTS

With this method, we could expose most of the structures of the region anatomically and imagenologically.

DISCUSSION

The zone can be approached for dissection with magnification and the habitual microsurgical instruments with satisfactory results. We think that fibers in this region should be followed by other anatomical methods in addition to tractography. The principal structures of ventral striopallidum and extended amygdala (EA) can be identified with the SPACE sequence. The amygdala and the basal ganglion of Meynert (BGM) are easily confused because of their similar signal. Anatomical clues can orient the clinician about the different clusters of the BGM in MRI.

CONCLUSIONS

The dissection requires a previous knowledge of the zone and a good amount of patience. The APS is a little space where concentrate essential vessels for the telencephalon, "en passage" or perforating, and neural structures of relevant functional import. From anatomical and MRI points of view, both neural and vascular structures follow a harmonious and topographically describable plan. The SPACE MRI sequence has proved to be a useful tool for identifying different structures in this area as the striatopallidal and EA. Anatomical knowledge of the fibers helps in the search of clusters of the basal ganglion.

Role of endoscopic third ventriculostomy in patients undergoing resection of pulvinar area lesions: Preliminary clinical results

BACKGROUND

Patients with pulvinar area lesions may develop hydrocephalus at any stage. The role of endoscopic third ventriculostomy (ETV) in this setting remains unclear.

METHOD

We retrospectively enrolled 15 patients with a mean age of 43 years who underwent endoscopic resection of pulvinar area lesions using the supracerebellar infratentorial approach (SCITA). We compared the different modalities of hydrocephalus management and their outcomes.

RESULTS

Nine of 15 patients (60.0%) had preoperative obstructive hydrocephalus. Five patients underwent ETV before tumor resection, and none developed postoperative hydrocephalus. Four patients underwent one-stage surgery for tumor removal, and one patient with a polymorphous low-grade neuroepithelial tumor of the young required postoperative ETV. Another patient with diffuse astrocytoma and hydrocephalus underwent concurrent lamina terminalis fenestration and endoscopic resection via the SCITA, which resulted in the resolution of hydrocephalus. The preoperative ETV group had no major postoperative complications, while the non-ETV group had three (0/5 vs. 3/4, P = 0.048). The ETV group also had a shorter intensive care unit stay; however, the difference was not significant (1.2 vs. 2.8; P = 0.188). ETV was effective in alleviating symptoms of postoperative hydrocephalus in patients with midbrain-invading tumors.

CONCLUSION

Endoscopic surgery via the SCITA can address both tumor and hydrocephalus issues in some cases but has a higher surgical risk and postoperative hydrocephalus rate. Preoperative ETV can prevent these complications and improve postoperative outcomes.

Anatomic evaluation of the posterior temporal approach via the Heschl's gyrus to the thalamus, internal capsule, and atrium

OBJECTIVE

Posterior temporal craniotomy allows for the exposure of the superior surface of the planum temporale. Heschl's gyrus is the most prominent structure of the planum temporale and can be an anatomical landmark to approach deep brain structures such as the internal capsule, lateral thalamus, and ventricular atrium.

METHODS

Ten human cadavers' heads underwent a posterior bilateral temporal craniotomy and the microsurgical dissection of Heschl's gyrus was performed and variables were measured with a neuronavigation system and statistically analyzed.

RESULTS

The mean distance between the keyhole and Heschl's gyrus was 61.7 ± 7.3 mm, the mean distance between the stephanion to Heschl's gyrus was 40.8 ± 6.0 mm, and the mean distance between the temporal lobe and Heschl's gyrus was 54.9 ± 6.9 mm. The length of Heschl's gyrus was 24 ± 7.5 mm, and the inclination angle in the axial plane was 20.0 ± 3.7° having the vertex as its deepest point as the base on the surface of the temporal plane. From Heschl's gyrus, the distance from the surface to the internal capsule was 29.1 ± 5.6 mm, the distance to the lateral thalamus was 34.8 ± 7.3 mm, and the distance to the ventricular atrium was 39.6 ± 7.2 mm. No statistical difference was found between the right and left sides.

CONCLUSIONS

Through a posterior temporal craniotomy, the temporal planum is exposed by opening the Sylvian fissure, where Heschl's gyrus can be identified and used as a natural corridor to approach the internal capsule, the ventricular atrium, and the lateral thalamus.

Are Thalamic Intrinsic Lesions Operable? No-Man's Land Revisited by the Analysis of a Large Retrospective, Mono-Institutional, Cohort

Thalamic gliomas represent a heterogeneous subset of deep-seated lesions for which surgical removal is advocated, although clear prognostic factors linked to advantages in performance status or overall survival are still lacking. We reviewed our Institutional Cancer Registry, identifying patients who underwent surgery for thalamic gliomas between 2006 and 2020. Associations between possible prognostic factors such as tumor volume, grade, the extent of resection and performance status (PS), and overall survival (OS) were evaluated using univariate and multivariate survival analyses. We found 56 patients: 31 underwent surgery, and 25 underwent biopsy. Compared to biopsy, surgery resulted positively associated with an increase in the OS (hazard ratio, HR, at multivariate analysis 0.30, 95% confidence interval, CI, 0.12-0.75). Considering the extent of resection (EOR), obtaining GTR/STR appeared to offer an OS advantage in high-grade gliomas (HGG) patients submitted to surgical resection if compared to biopsy, although we did not find statistical significance at multivariate analysis (HR 0.53, 95% CI 0.17-1.59). Patients with a stable 3-month KPS after surgery demonstrated to have a better prognosis in terms of OS if compared to biopsy (multivariate HR 0.17, 95% CI, 0.05-0.59). Age and histological grades were found to be prognostic factors for this condition (p = 0.04 and p = 0.004, respectively, chi-square test). Considering the entire cohort, p53 positivity (univariate HR 2.21, 95% CI 1.01-4.82) and ATRX positivity (univariate HR 2.69, 95% CI 0.92-7.83) resulted associated with a worse prognosis in terms of OS. In this work, we demonstrated that surgery aimed at tumor resection might offer a stronger survival advantage when a stable 3-month KPS after surgery is achieved.

Contralateral Anterior Interhemispheric–Transcallosal–Transrostral Approach for the Resection of a Subcallosal Cavernous Malformation: A Case Report and an Operative Video

This case report demonstrates the surgical resection of a cerebral cavernous malformation located in the subcallosal region. The authors present a detailed operative video explaining the steps to successfully remove the lesion through a contralateral interhemispheric–transcallosal–transrostral approach with the patient in lateral decubitus. The surgical procedure was uneventful, and the patient had no postoperative deficits and no residual lesions in a three-month follow-up.

Survival and functional outcomes in paediatric thalamic and thalamopeduncular low grade gliomas

BACKGROUND

Childhood thalamopeduncular gliomas arise at the interface of the thalamus and cerebral peduncle. The optimal treatment is total resection but not at the cost of neurological function. We present long-term clinical and oncological outcomes of maximal safe resection.

METHODS

Retrospective review of prospectively collected data: demography, symptomatology, imaging, extent of resection, surgical complications, histology, functional and oncological outcome.

RESULTS

During 16-year period (2005-2020), 21 patients were treated at our institution. These were 13 girls and 8 boys (mean age 7.6 years). Presentation included progressive hemiparesis in 9 patients, raised intracranial pressure in 9 patients and cerebellar symptomatology in 3 patients. The tumour was confined to the thalamus in 6 cases. Extent of resection was judged on postoperative imaging as total (6), near-total (6) and less extensive (9). Surgical complications included progression of baseline neurological status in 6 patients, and 5 of these gradually improved to preoperative status. All tumours were classified as low-grade gliomas. Disease progression was observed in 9 patients (median progression-free survival 7.3 years). At last follow-up (median 6.1 years), all patients were alive, median Lansky score of 90. Seven patients were without evidence of disease, 6 had stable disease, 7 stable following progression and 1 had progressive disease managed expectantly.

CONCLUSION

Paediatric patients with low-grade thalamopeduncular gliomas have excellent long-term functional and oncological outcomes when gross total resection is not achievable. Surgery should aim at total resection; however, neurological function should not be endangered due to excellent chance for long-term survival.

Contralateral Interhemispheric Transcallosal Approach for Thalamic Cystic Cavernous Malformation

A 42-year-old man presented with a headache and right hemiparesis and was found to have a cystic mass with a calcified mural nodule in the left thalamus. Because the thalamus is surrounded by vital neurovascular structures, the surgical approach to thalamic lesions can be challenging. We decided to remove the mass for decompression and pathological diagnosis. The mass was removed through a contralateral interhemispheric transcallosal transchoroidal approach with less retraction and parenchymal injury than other approaches to avoid brain retraction and cortical injury. The pathological diagnosis was cavernous malformation. Temporary worsening of the preoperative hemiparesis was recovered over two months following surgery. Tolerable thalamic pain syndrome remained. Here, we report a rare case of thalamic cavernous malformation with a favorable outcome through a contralateral surgical approach.

Microneurosurgical removal of thalamic lesions: surgical results and considerations from a large, single-surgeon consecutive series

OBJECTIVE

The object of this study was to present the surgical results of a large, single-surgeon consecutive series of patients who had undergone transcisternal (TCi) or transcallosal-transventricular (TCTV) endoscope-assisted microsurgery for thalamic lesions.

METHODS

This is a retrospective study of a consecutive series of patients harboring thalamic lesions and undergoing surgery at one institution between February 2007 and August 2019. All surgical and patient-related data were prospectively collected. Depending on the relationship between the lesion and the surgically accessible thalamic surfaces (lateral ventricle, velar, cisternal, and third ventricle), one of the following surgical TCi or TCTV approaches was chosen: anterior interhemispheric transcallosal (AIT), posterior interhemispheric transtentorial subsplenial (PITS), perimedian supracerebellar transtentorial (PeST), or perimedian contralateral supracerebellar suprapineal (PeCSS). Since January 2018, intraoperative MRI has also been part of the protocol. The main study outcome was extent of resection. Complete neurological examination took place preoperatively, at discharge, and 3 months postoperatively. Descriptive statistics were calculated for the whole cohort.

RESULTS

In the study period, 92 patients underwent surgery for a thalamic lesion: 81 gliomas, 6 cavernous malformations, 2 germinomas, 1 metastasis, 1 arteriovenous malformation, and 1 ependymal cyst. In none of the cases was a transcortical approach adopted. Thirty-five patients underwent an AIT approach, 35 a PITS, 19 a PeST, and 3 a PeCSS. The mean follow-up was 38 months (median 20 months, range 1-137 months). No patient was lost to follow-up. The mean extent of resection was 95% (median 100%, range 21%-100%), and there was no surgical mortality. Most patients (59.8%) experienced improvement in their Karnofsky Performance Status. New permanent neurological deficits occurred in 8 patients (8.7%). Early postoperative (< 3 months after surgery) problems in CSF circulation requiring diversion occurred in 7 patients (7.6%; 6/7 cases in patients with high-grade glioma).

CONCLUSIONS

Endoscope-assisted microsurgery allows for the removal of thalamic lesions with acceptable morbidity. Surgeons must strive to access any given thalamic lesion through one of the four accessible thalamic surfaces, as they can be reached through either a TCTV or TCi approach with no or minimal damage to normal brain parenchyma. Patients harboring a high-grade glioma are likely to develop a postoperative disturbance of CSF circulation. For this reason, the AIT approach should be favored, as it facilitates a microsurgical third ventriculocisternostomy and allows intraoperative MRI to be done.

Endoscopic Surgery for Supratentorial Deep Cavernous Malformation Adjacent to Cortical Spinal Tract: Preliminary Experience and Technical Note

In this study, we aimed to introduce a technical note and to explore the efficacy of endoscopic surgery combined with diffusion tensor imaging (DTI) navigation for supratentorial deep cerebral cavernous malformations (CCM). A prospectively maintained database of CCM patients was reviewed to identify all CCM patients treated by endoscopic surgery. The sagittal T1-weighted anatomical magnetic resonance imaging (MRI) and DTI were acquired before surgery. Endoscopic surgery was planned and performed based on preoperative DTI images and intraoperative DTI navigation. All patients were followed up more than 6 months. Motor function deficit and modified Rankin scale (mRS) scores were documented on follow-up. A final mRS score of 0–2 was considered a good outcome, and a final mRS score >2 was considered a poor outcome. Second DTI and 3DT1 were performed at 3 months after surgery. We tracked the ipsilateral corticospinal tract (CST) on pre- and postoperative DTI images. The overall mean FA values and the number of fibers of tracked CST were compared on pre- and postoperative DTI images. Risk factors associated with motor deficits and poor outcomes were analyzed. Seven patients with deep CCM and treated by endoscopic surgery were enrolled in this study. The mean value of preoperative mRS was 1.5 ± 0.98, but that score recovered to 0.86 ± 1.22 3 months later. The mRS scores were improved significantly according to statistical analysis (p = 0.012). According to the Spearman non-parametric test, only the fiber number of ipsilateral CST on postoperative DTI was significantly associated with muscle strength 6 months after surgery (p = 0.032). Compared with preoperative CST characteristics on DTI, the change of FA value (p = 0.289) and fiber number (p = 0.289) of ipsilateral CST on postoperative DTI was not significant It meant that the CST was protected during endoscopic surgery. Endoscopic surgery based on DTI navigation might be an effective method to protect fiber tracts in supratentorial deep CCM patients and improve long-term outcomes. However, more studies and cases are needed to confirm our findings.

Maximal surgical resection and adjuvant surgical technique to prolong the survival of adult patients with thalamic glioblastoma

The importance of maximal resection in the treatment of glioblastoma (GBM) has been reported in many studies, but maximal resection of thalamic GBM is rarely attempted due to high rate of morbidity and mortality. The purpose of this study was to investigate the role of surgical resection in adult thalamic glioblastoma (GBM) treatment and to identify the surgical technique of maximal safety resection. In case of suspected thalamic GBM, surgical resection is the treatment of choice in our hospital. Biopsy was considered when there was ventricle wall enhancement or multiple enhancement lesion in a distant location. Navigation magnetic resonance imaging, diffuse tensor tractography imaging, tailed bullets, and intraoperative computed tomography and neurophysiologic monitoring (transcranial motor evoked potential and direct subcortical stimulation) were used in all surgical resection cases. The surgical approach was selected on the basis of the location of the tumor epicenter and the adjacent corticospinal tract. Among the 42 patients, 19 and 23 patients underwent surgical resection and biopsy, respectively, according to treatment strategy criteria. As a result, the surgical resection group exhibited a good response with overall survival (OS) (median: 676 days, p < 0.001) and progression-free survival (PFS) (median: 328 days, p < 0.001) compared with each biopsy groups (doctor selecting biopsy group, median OS: 240 days and median PFS: 134 days; patient selecting biopsy group, median OS: 212 days and median PFS: 118 days). The surgical resection groups displayed a better prognosis compared to that of the biopsy groups for both the O6-methylguanine-DNA methyltransferase unmethylated (log-rank p = 0.0035) or methylated groups (log-rank p = 0.021). Surgical resection was significantly associated with better prognosis (hazard ratio: 0.214, p = 0.006). In case of thalamic GBM without ventricle wall-enhancing lesion or multiple lesions, maximal surgical resection above 80% showed good clinical outcomes with prolonged the overall survival compared to biopsy. It is helpful to use adjuvant surgical techniques of checking intraoperative changes and select the appropriate surgical approach for reducing the surgical morbidity.

How I do it: parietal trans-sulcal para-fascicular approach to lateral thalamic/internal capsule cavernous malformation

BACKGROUND

The surgical management of deep brain lesions is challenging, with significant morbidity. Advances in surgical technology have presented the opportunity to tackle these lesions.

METHODS

We performed a complete resection of a thalamic/internal capsule CM using a tubular retractor system via a parietal trans-sulcal para-fascicular (PTPF) approach without collateral injury to the nearby white matter tracts.

CONCLUSION

PTPF approach to lateral thalamic/internal capsule lesions can be safely performed without injury to eloquent white matter fibres. The paucity of major vessels along this trajectory and the preservation of lateral ventricle integrity make this approach a feasible alternative to traditional approaches.

Quantitative analysis of ipsilateral and contralateral supracerebellar infratentorial and occipital transtentorial approaches to the cisternal pulvinar: laboratory anatomical investigation

OBJECTIVE

The cisternal pulvinar is a challenging location for neurosurgery. Four approaches for reaching the pulvinar without cortical transgression are the ipsilateral supracerebellar infratentorial (iSCIT), contralateral supracerebellar infratentorial (cSCIT), ipsilateral occipital transtentorial (iOCTT), and contralateral occipital transtentorial/falcine (cOCTF) approaches. This study quantitatively compared these approaches in terms of surgical exposure and maneuverability.

METHODS

Each of the 4 approaches was performed in 4 cadaveric heads (8 specimens in total). A 6-sided anatomical polygonal region was configured over the cisternal pulvinar, defined by 6 reachable anatomical points in different vectors. Multiple polygons were subsequently formed to calculate the areas of exposure. The surgical freedom of each approach was calculated as the maximum allowable working area at the proximal end of a probe, with the distal end fixed at the posterior pole of the pulvinar. Areas of exposure, surgical freedom, and the working distance (surgical depth) of all approaches were compared.

RESULTS

No significant difference was found among the 4 different approaches with regard to the surgical depth, surgical freedom, or medial exposure area of the pulvinar. In the pairwise comparison, the cSCIT approach provided a significantly larger lateral exposure (39 ± 9.8 mm2) than iSCIT (19 ± 10.3 mm2, p < 0.01), iOCTT (19 ± 8.2 mm2, p < 0.01), and cOCTF (28 ± 7.3 mm2, p = 0.02) approaches. The total exposure area with a cSCIT approach (75 ± 23.1 mm2) was significantly larger than with iOCTT (43 ± 16.4 mm2, p < 0.01) and iSCIT (40 ± 20.2 mm2, p = 0.01) approaches (pairwise, p ≤ 0.01).

CONCLUSIONS

The cSCIT approach is preferable among the 4 compared approaches, demonstrating better exposure to the cisternal pulvinar than ipsilateral approaches and a larger lateral exposure than the cOCTF approach. Both contralateral approaches described (cSCIT and cOCTF) provided enhanced lateral exposure to the pulvinar, while the cOCTF provided a larger exposure to the lateral portion of the pulvinar than the iOCTT. Medial exposure and maneuverability did not differ among the approaches. A short tentorium may negatively impact an ipsilateral approach because the cingulate isthmus and parahippocampal gyrus tend to protrude, in which case they can obstruct access to the cisternal pulvinar ipsilaterally.

Surgical treatment and survival outcome of patients with adult thalamic glioma: a single institution experience of 8 years

PURPOSE

Given the rarity in the population with adult thalamic gliomas (ATGs), comprehensive characteristics, treatments and survival outcome are not well characterized. This study was conducted to investigate the comprehensive characteristic and treatment of ATGs and identify the prognostic factors associated with overall survival (OS).

METHODS

A retrospective analysis of newly diagnosed ATGs who underwent surgical resection consecutively was conducted. Survival analysis of OS was performed by Kaplan-Meier analysis. Cox proportional hazard model was used to investigate the possible prognostic factors associated with OS.

RESULTS

A total of 102 patients with ATG were enrolled in this study. The median age was 41 years (range 18-68 years). There were 56 (54.9%) males. Sixty-two patients (60.8%) had glioblastoma (GBM). Among these patients, 46 patients (45.1%) had GTR/NTR, 50 patients (49.0%) had STR and 6 patients (5.9%) had PR. Postoperatively, 71.6% of these patients received adjuvant therapy. The median OS was 13.6 months (range 1 week-75 months). COX regression analysis revealed that ATG patients with longer duration of symptoms (p = 0.024), better pre-KPS (p = 0.045), maximal resection (p = 0.013), or lower tumor grade (p = 0.002) had longer OS, and these predictors are considered as independent prognostic factors. Survival analysis showed that ATGs with GTR/NTR plus chemoradiotherapy had significant OS advantage compared with other treatment regimens.

CONCLUSIONS

This study comprehensively summarized the characteristics, treatments and survival outcomes of ATGs in the largest sample size. Maximal surgical resection can bring survival benefit. Combined-modality therapy regimen of GTR/NTR plus chemoradiotherapy may be better beneficial for OS than other regimens.

Outcomes of basal ganglia and thalamic cavernous malformation surgery: A meta-analysis

Surgical resection of basal ganglia (BG) and thalamic cavernous malformations (CMs) has not yet become standardized in the field of neurosurgery due to the eloquent location of these lesions and the relative paucity of literature on the subject. This review presents a consolidation of the available literature on outcomes and complication rates after surgical resection of these lesions. A systematic literature review was performed via PubMed database for articles published between 1985 and 2019. Studies comprising ≥2 patients receiving surgery for BG or thalamic CMs with available follow-up data were included. Pooled data included patient demographics, CM preoperative characteristics, and surgical outcomes Twenty studies comprising 227 patients were included for analysis. Complete resection was achieved in 94.7% (fixed-effects pooled estimate [FE]: 94.9%[91.0%-97.8%]; random-effects pooled estimate [RE]: 90.0%[79.8%-96.9%]), and hemorrhage of incompletely resected CMs occurred in 50% (FE: 55.9%[25.9%-83.6%]; RE: 55.9%[25.9%-83.6%]) of patients. Early morbidity was observed in 24.0% (FE: 24.9%[17.8%-32.6%]; RE: 24.9%[17.8%-32.6%]). At final follow-up, 67.3% (FE: 67.7%[58.8%-76.0%]; RE: 67.8%[52.2%-81.6%]) and 20.6% (FE: 20.6%[13.6%-28.6%]; RE: 20.9%[9.8%-34.9%]) had improvement and stability of preoperative symptoms, respectively. Mortality rate was 1.3% (FE: 2.3%[0.6%-5.1%]; RE: 2.3%[0.6%-5.1%]). Therefore, high cure rates with low rates of postoperative morbidity can be achieved in BG or thalamic CM surgery. Most patients had improved neurological function at final follow-up. Complete resection should be attempted to reduce rates of repeat hemorrhage.

Supratentorial Cavernous Malformations Involving the Corticospinal Tract and Sensory Motor Cortex: Treatment Strategies, Surgical Considerations, and Outcomes

BACKGROUND

Cavernous malformations (CMs) are congenital malformations and may be located anywhere in the brain. We present a series of CMs located close to or inside of the motor-sensory cortex or corticospinal tract (CST) with clinical onset due to hemorrhage or mass effect. In such cases, surgery becomes an acceptable option.

OBJECTIVE

To evaluate the role of diffusion tensor imaging (DTI), functional-magnetic-resonance imaging (fMRI), intraoperative neurophysiological monitoring, neuronavigation, and brain-mapping and the clinical results of surgical treatment of CMs in this critical location.

METHODS

The study included 54 patients harboring 22 cortical and 32 deep locations. This series was distinct because in group I, where the DTI was not obtained, and in the group II, where this evaluation was performed.

RESULTS

The postoperative permanent morbidity rate was 4% in the historical group for the deeper CMs, and there was no morbidity in the second group. DTI and fMRI permitted us to estimate the distance between the CMs and both the cortical activation cluster and the pyramidal tract. These data, in addition to intraoperative mapping and monitoring, made it necessary for us to perform a partial resection in 2 cases in the second series.

CONCLUSION

CMs are congenital lesions and CST fibers can run directly on their surface. Integration of fMRI and DTI data with intraoperative functional monitoring and direct cortical and subcortical mapping are mandatory to accomplish an optimal resection, tailoring the best surgical approach to the acceptable morbidity. A subtotal resection could be considered an option for deep locations.

Cavernous Malformations in and Around the Third Ventricle: Indications, Approaches, and Outcomes

BACKGROUND

Cavernous malformations in structures in and around the third ventricle are a challenging conceptual and surgical problem. No consensus exists on the ideal approach to such lesions.

OBJECTIVE

To perform a retrospective review of our institutional database to identify and evaluate approaches used to treat cavernous malformations located in and around the third ventricle.

METHODS

Information was extracted regarding lesion size and location, extent of resection, time to last follow-up, surgical approach, presenting symptoms, preoperative and postoperative neurological status, and specific approach-related morbidity.

RESULTS

All 39 neurosurgical operations (in 36 patients) were either an anterior interhemispheric (AIH) (44%, 17/39) or a supracerebellar infratentorial (SCIT) (56%, 22/39) approach. Gross-total resection was achieved in 23 of 39 procedures (59%), a near-total resection in 1 (3%), and subtotal resection in 15 (38%). For the 31 patients with at least 3 mo of follow-up, the mean modified Rankin Scale (mRS) score was 1.5. Of the 31 patients, 25 (81%) had an mRS score of 0 to 2, 4 had a mRS score of 3 (13%), and 1 each had a mRS score of 4 (3%) or 5 (3%).

CONCLUSION

Most approaches to cavernous malformations in and around the third ventricle treated at our institution have been either an AIH or a SCIT approach. The AIH approach was used for lesions involving the lateral wall of the third ventricle or the midline third ventricular floor, whereas the SCIT approach was used for lesions extending from the third ventricle into the dorsolateral midbrain, with acceptable clinical results.

A contralateral transventricular approach for microsurgical clip ligation of a ruptured intrathalamic aneurysm

Intrathalamic aneurysms are a cause of patient morbidity and mortality. Aneurysms in this location can be accessed microsurgically when they cannot be accessed endovascularly. Care must be taken to avoid critical white matter tracts when approaching the thalamus microsurgically. Use of a tubular retractor can offer safe brain retraction during the approach. A 53-year-old female with a history of hypertension and cerebrovascular accidents presented with slurred speech, altered mental status, and right-sided weakness. CT demonstrated an acute parenchymal hemorrhage within the left thalamus and the internal capsule. CT angiography demonstrated a left dorsal thalamic aneurysm. Following angiography with consideration for embolization, the patient was taken to the operating room for microsurgical clip ligation with the use of minimally invasive techniques. The aneurysm was accessed using a contralateral transventricular approach with a tubular retractor for microsurgical clip ligation. Postoperative imaging demonstrated successful interval clipping of the aneurysm within the thalamus. This is the first report using our described surgical approach for treatment of a dorsal intrathalamic aneurysm. We combined the use of diffusion tensor imaging with a tubular retractor to clip a dorsal thalamic aneurysm.

Surgical Anatomy of the Subcallosal Artery: Implications for Transcranial and Endoscopic Endonasal Surgery in the Suprachiasmatic Region

BACKGROUND

Suprachiasmatic subcallosal lesions may have an intimate relationship with the anterior communicating artery (AcomA); injury to AcomA branches can result in basal forebrain infarction and cognitive dysfunction.

OBJECTIVE

To evaluate anatomic variations of the AcomA basal perforating branches, especially the subcallosal artery (ScA), for clinical implications when approaching the suprachiasmatic subcallosal region from endonasal and transcranial routes.

METHODS

The origin, course, diameter, and branching pattern of the AcomA's perforating branches were studied in 33 specimens from transcranial and endonasal perspectives.

RESULTS

The ScA was present in 79% of the specimens as a single dominant artery arising from the posterior/posterosuperior surface of the AcomA, along with hypothalamic arteries (55%), or as a single artery (24%). It coursed posteriorly towards the lamina terminalis region, curving superiorly to the subcallosal area. The ScA gave off many branches to provide the main blood supply to the subcallosal region. Importantly, it supplies the septal/subcallosal region bilaterally. The ScA can be found posterior, superior, or inferior to the AcomA when using a transylvian, interhemispheric, or endonasal approach, respectively. In specimens with no ScA (21%), the median callosal artery (MdCA) was the dominant artery arising from the AcomA. It followed an identical course to the ScA, providing supply to the same structures bilaterally, but its distal extension reached the body/splenium of the corpus callosum. The MdCA is a ScA variant.

CONCLUSION

The ScA is a unique vessel because it supplies the septal/subcallosal region bilaterally; preservation of this vessel during surgery is crucial for successful outcomes.

Supracerebellar transtentorial resection of a ruptured thalamomesencephalic cavernous malformation

Thalamomesencephalic cavernous malformations are located high in the brainstem and may be difficult to reach. We present a case of such a lesion which was successfully approached via the supracerebellar transtentorial route. Our enclosed video provides elements to justify this posterior approach and illustrates the steps required for the cavernoma’s safe removal, which include opening of the tentorium and gentle retraction of the exposed temporal lobe.

The video can be found here: https://youtu.be/Ex5OfLyBzPY.

A White Matter Fiber Microdissection Study of the Anterior Perforated Substance and the Basal Forebrain: A Gateway to the Basal Ganglia?

BACKGROUND

Studies detailing the anatomy of the basal forebrain (BF) from a neurosurgical perspective are missing.

OBJECTIVE

To describe the anatomy of the BF and of the anterior perforated substance (APS), the BF emphasizing surgical useful anatomical relationship between surface landmarks and deep structures.

METHODS

White matter fiber microdissection was performed on 5 brain specimens to analyze the topographic anatomy of the APS and expose layer-by-layer fiber tracts and nuclei of the BF.

RESULTS

The APS, as identified anatomically, surgically, and neuroradiologically, has clear borders measured 23.3 ± 3.4 mm (19-27) in the mediolateral and 12.5 ± 1.2 mm (11-14) in the anteroposterior directions. A detailed stratigraphy of the BF was performed from the APS up to basal ganglia and thalamus allowing identification and dissection of the main components of the BF (septum, nucleus accumbens, amygdala, innominate substance) and its white matter tracts (band of Broca, extracapsular thalamic peduncle, ventral amygdalohypothalamic fibers). The olfactory trigone together with diagonal gyrus and the APS proper is a relevant superficial landmark for the basal ganglia (inferior to the nucleus accumbens, lateral to the caudate head, and medial to the lentiform nucleus).

CONCLUSION

The findings in our study supplement available anatomic knowledge of APS and BF, providing reliable landmarks for precise topographic diagnosis of BF lesions and for intraoperative orientation. Surgically relevant relationships between surface and deep anatomic structures are highlighted offering thus a contribution to neurosurgeons willing to perform surgery in this delicate area.

Supracerebellar Infratentorial and Occipital Transtentorial Approaches to the Pulvinar: Ipsilateral Versus Contralateral Corridors

BACKGROUND

Due to the critical neurovascular structures that surround the pulvinar, deciding the best surgical approach can be challenging, with multiple options available.

OBJECTIVE

To analyze and compare the ipsilateral vs the contralateral version of the 2 main approaches to the cisternal pulvinar surface: paramedian supracerebellar infratentorial (PSCI) and interhemispheric occipital transtentorial (IOT).

METHODS

The PSCI and IOT approaches were performed on 7 formalin-fixed adult cadaveric heads to evaluate qualitatively and quantitatively the microsurgical exposure of relevant anatomic structures. We quantitatively measured the corridor distance to our target with each approach.

RESULTS

The ipsilateral PSCI approach provided an easier access and a better exposure of the anteromedial portion of the cisternal pulvinar surface. The contralateral approach provided a wider and more accessible exposure of the posterolateral portion of the cisternal pulvinar surface. When protrusion of the posterior parahippocampal gyrus above the free edge of the tentorium was present, the contralateral PSCI approach provided an unobstructed view to both areas. The IOT approach provided a better view of the anteromedial portion of the cisternal pulvinar surface, especially with a contralateral approach.

CONCLUSION

Multiple approaches to the pulvinar have been described, modified, and improved. Based on this anatomic study we believe that although the corridor distance with a contralateral approach is longer, the surgical view and access can be better. We recommend the use of a PSCI contralateral approach especially when a significant protrusion of the posterior parahippocampal gyrus is present.

The Superior Thalamic Vein and its Variations: A Proposed Classification

BACKGROUND

The superior thalamic vein (STV) was first described comprehensively by Ferner in 1958 as the most prominent thalamic vein; it originates from the central superior portion of the thalamus, coursing medially to the third ventricular thalamic surface, where it turns posteriorly to parallel the internal cerebral vein (ICV) before ending into its posterior portion. Since historical anatomic and angiographic studies in the pre-computed tomography (CT)/magnetic resonance imaging era, the STV has not been investigated.

OBJECTIVE

To describe the anatomic course of the STV with its variations, and to propose a classification system based on its draining pattern.

METHODS

We retrospectively screened our imaging database for 50 patients who had a CT-angiography with predefined parameters. The images were independently reviewed by 3 neurosurgeons and 1 neuroradiologist to classify the STV into 4 types: type 1A-drainage into the anterior portion of the ICV, type 1B-drainage into the posterior portion of the ICV, type 2-drainage into the vein of Rosenthal, type 3-drainage into a medial (3A) or lateral (3B) atrial vein, and type 4-drainage into the vein of Galen.

RESULTS

In 50 patients, we could identify 96 STVs. In 2 hemispheres, the STV was doubled. The 92 single STVs were classified as type 1A in 25 hemispheres (27.2%), type 1B in 45 (48.9%), type 2 in 12 (13.0%), type 3A in 8 (8.7%), type 3B in 1 (1.1%), and type 4 in 1 (1.1%).

CONCLUSION

The draining pattern of the STV varies widely from the initial description.

[MR tractography in diagnosis and choice of a neurosurgical approach to basal ganglia tumors]

We describe two cases of surgical treatment of well-circumscribed basal ganglia tumors. The choice of a neurosurgical approach to a deep tumor was based on the MR tractography data and depended on the course and dislocation extent of the corticospinal tract. MR tractography provides information on the course and dislocation or destruction extent of the corticospinal tract running in the internal capsule and brainstem and clarifies the exact location of a tumor within the basal ganglia. This information promotes the choice of an optimal approach for radical resection of well-circumscribed tumor, leading to improvement in neurological symptoms and patient's quality of life.

Contralateral Supracerebellar-Infratentorial Approach for Resection of Thalamic Cavernous Malformations

BACKGROUND

Surgical resection of cavernous malformations (CM) in the posterior thalamus, pineal region, and midbrain tectum is technically challenging owing to the presence of adjacent eloquent cortex and critical neurovascular structures. Various supracerebellar infratentorial (SCIT) approaches have been used in the surgical armamentarium targeting lesions in this region, including the median, paramedian, and extreme lateral variants. Surgical view of a posterior thalamic CM from the traditional ipsilateral vantage point may be obscured by occipital lobe and tentorium.

OBJECTIVE

To describe a novel surgical approach via a contralateral SCIT (cSCIT) trajectory for resecting posterior thalamic CMs.

METHODS

From 1997 to 2017, 75 patients underwent the SCIT approach for cerebrovascular/oncologic pathology by the senior author. Of these, 30 patients underwent the SCIT approach for CM resection, and 3 patients underwent the cSCIT approach. Historical patient data, radiographic features, surgical technique, and postoperative neurological outcomes were evaluated in each patient.

RESULTS

All 3 patients presented with symptomatic CMs within the right posterior thalamus with radiographic evidence of hemorrhage. All surgeries were performed in the sitting position. There were no intraoperative complications. Neuroimaging demonstrated complete CM resection in all cases. There were no new or worsening neurological deficits or evidence of rebleeding/recurrence noted postoperatively.

CONCLUSION

This study establishes the surgical feasibility of a contralateral SCIT approach in resection of symptomatic thalamic CMs It demonstrates the application for this procedure in extending the surgical trajectory superiorly and laterally and maximizing safe resectability of these deep CMs with gravity-assisted brain retraction.

Supratentorial cavernous malformations adjacent to the corticospinal tract: surgical outcomes and predictive value of diffusion tensor imaging findings

OBJECTIVE

Diffusion tensor imaging (DTI) findings may facilitate clinical decision making in patients with supratentorial cavernous malformations adjacent to the corticospinal tract (CST-CMs). The objective of this study was to determine the predictive value of preoperative DTI findings for surgical outcomes in patients with CST-CMs.

METHODS

A prospectively maintained database of patients with CM referred to the authors' hospital between September 2012 and October 2015 was reviewed to identify all consecutive surgically treated patients with CST-CM. All patients had undergone sagittal T1-weighted anatomical imaging and DTI before surgery. Both DTI findings and clinical characteristics of the patients and lesions were analyzed with respect to surgery-related motor deficits. DTI findings included lesion-to-CST distance (LCD) and the alteration (i.e., deviation, interruption, or degeneration due to the CM) of CST on preoperative DTI images. Surgery-related motor deficits at 1 week and the last clinic visit (≥ 3 months) after surgery were defined as short-term and long-term deficits, respectively. Preoperative and final modified Rankin Scale scores were also analyzed to identify the surgical outcomes in these patients.

RESULTS

A total of 56 patients with 56 CST-CMs were included in this study. The mean LCD was 3.9 ± 3.2 mm, and alterations of the CST were detected in 20 (36.7%) patients. One week after surgery, 21 (37.5%) patients had short-term surgery-related motor deficits, but only 14 (25.0%) patients had long term deficits at the last clinical visit. The mean patient follow-up was 14.7 ± 10.1 months. The difference between preoperative and final modified Rankin Scale scores was not statistically significant (p = 0.490). Multivariate analysis showed that both short-term (p < 0.001) and long-term (p = 0.002) surgery-related motor deficits were significantly associated with LCD. Receiver operating characteristic (ROC) curve results were as follows: for short-term surgery-related motor deficits, the area under the ROC curve (AUC) was 0.860, and the cutoff point was LCD = 2.55 mm; for long-term deficits, the AUC was 0.894, and the cutoff point was LCD = 2.30 mm. Both univariate (p = 0.012) and multivariate (p = 0.049) analyses revealed that CST alteration on preoperative DTI was significantly correlated with short-term surgery-related motor deficits. On univariate analysis, deep location of the CST-CMs was significantly correlated with long-term motor deficits (p = 0.016). Deep location of the CST-CMs had a trend toward significance with long-term motor deficits on the multivariate analysis (p = 0.060).

CONCLUSIONS

To facilitate clinical practice, the authors propose that 3.00 mm (2.55 to ∼3.00 mm) may be the safe LCD for surgery in patients with CST-CMs. A CST alteration on preoperative DTI and a deep location of the CST-CM may be risk factors for short- and long-term surgery-related motor deficits, respectively. A randomized controlled trial is needed to demonstrate the predictive value of preoperative DTI findings on surgical outcomes in patients with CST-CMs in future studies.

Contralateral anterior interhemispheric-transcallosal-transrostral approach to the subcallosal region: a novel surgical technique

OBJECTIVE The authors report a novel surgical route from a superior anatomical aspect-the contralateral anterior interhemispheric-transcallosal-transrostral approach-to a lesion located in the subcallosal region. The neurosurgical approach to the subcallosal region is challenging due to its deep location and close relationship with important vascular structures. Anterior and inferior routes to the subcallosal region have been described but risk damaging the branches of the anterior cerebral artery. METHODS Three formalin-fixed and silicone-injected adult cadaveric heads were studied to demonstrate the relationships between the transventricular surgical approach and the subcallosal region. The surgical, clinical, and radiological history of a 39-year-old man with a subcallosal cavernous malformation was retrospectively used to document the neurological examination and radiographic parameters of such a case. RESULTS The contralateral anterior interhemispheric-transcallosal-transrostral approach provides access to the subcallosal area that also includes the inferior portion of the pericallosal cistern, lamina terminalis cistern, the paraterminal and paraolfactory gyri, and the anterior surface of the optic chiasm. The approach avoids the neurocritical perforating branches of the anterior communicating artery. CONCLUSIONS The contralateral anterior interhemispheric-transcallosal-transrostral approach may be an alternative route to subcallosal area lesions, with less risk to the branches of the anterior cerebral artery, particularly the anterior communicating artery perforators.

Cavernous malformations of central nervous system in pediatric patients: our single-centered experience in 50 patients and review of literature

PURPOSE

Cavernous malformations (CMs) are rare developmental cerebrovascular malformations of the central nervous system with a childhood prevalence of 0.3 to 0.53%. Our purpose was to assess the clinical features and microsurgical outcome in pediatric central nervous system (CNS) CMs.

MATERIAL AND METHODS

We retrospectively enrolled all the CM patients admitted to our institute from 1 January 2001 to 31 December 2014. Data was analyzed for their clinical features and surgical outcome.

RESULTS

A total of 50 patients with CMs (30 supratentorial, 14 infratentorial, and 6 spinal) with a mean age of 14 years (3-18 years, SD ±4.64) were enrolled into the study. Most of these patients (78%) were male. Size varied from 1.2 to 6 cm. Three patients had multiple CMs. Symptoms of CMs were site specific. Seizure was the most common symptom (63.3%) of CMs at supratentorial location followed by headache (46%) and neurodeficiency (26%), while all brainstem and spinal CMs presented with neurodeficiencies. History of clinically significant acute hemorrhage was present in 19.2% of supratentorial (ST) superficial CMs, 50% of ST deep CMs, 25% of cerebellar CMs, 44.4% of brainstem CMs, and 50% of spinal CMs. Forty-five CMs in 44 patients were surgically excised. Their follow-up ranged from 6 to 162 months (mean 47.2 months, SD ±53). All supratentorial CM patients showed improvement in their symptoms. Patients with preoperative seizure showed good seizure control with Engel scale I in 16 (94.1%) and Engel scale II in 1 (5.9%). In infratentorial (IT) and spinal CM patients, 92.3 and 66.7% had improvement in their neurodeficiencies, respectively. There was no mortality in our series.

CONCLUSION

Microsurgical excision of CNS CM results in excellent neurological outcome in pediatric patients. Early intervention is necessary in spinal CMs for better outcome.

Microsurgical and endoscopic approaches to the pulvinar

OBJECTIVE

Approaches to the pulvinar remain challenging because of the depth of the target, surrounding critical neural structures, and complicated arterial and venous relationships. The purpose of this study was to compare the surgical approaches to different parts of the pulvinar and to examine the efficacy of the endoscope as an adjunct to the operating microscope in this area.

METHODS

The pulvinar was examined in 6 formalin-fixed human cadaveric heads through 5 approaches: 4 above and 1 below the tentorium. Each approach was performed using both the surgical microscope and 0° or 45° rigid endoscopes.

RESULTS

The pulvinar has a lateral ventricular and a medial cisternal surface that are separated by the fornix and the choroidal fissure, which wrap around the posterior surface of the pulvinar. The medial cisternal part of the pulvinar can be further divided into upper and lower parts. The superior parietal lobule approach is suitable for lesions in the upper ventricular and cisternal parts. Interhemispheric precuneus and posterior transcallosal approaches are suitable for lesions in the part of the pulvinar forming the anterior wall of the atrium and adjacent cisternal part. The posterior interhemispheric transtentorial approach is suitable for lesions in the lower cisternal part and the supracerebellar infratentorial approach is suitable for lesions in the inferior and medial cisternal parts.

The microscope provided satisfactory views of the ventricular and cisternal surfaces of the pulvinar and adjacent neural and vascular structures. The endoscope provided multi-angled and wider views of the pulvinar and adjacent structures.

CONCLUSIONS

A combination of endoscopic and microsurgical techniques allows optimal exposure of the pulvinar.

Quantitative anatomical comparison of the ipsilateral and contralateral interhemispheric transcallosal approaches to the lateral ventricle

OBJECTIVE The best approach to deep-seated lateral and third ventricle lesions is a function of lesion characteristics, location, and relationship to the ventricles. The authors sought to examine and compare angles of attack and surgical freedom of anterior ipsilateral and contralateral interhemispheric transcallosal approaches to the frontal horn of the lateral ventricle using human cadaveric head dissections. Illustrative clinical experiences with a contralateral interhemispheric transcallosal approach and an anterior interhemispheric transcallosal transchoroidal approach are also related. METHODS Five formalin-fixed human cadaveric heads (10 sides) were examined microsurgically. CT and MRI scans obtained before dissection were uploaded and fused into the navigation system. The authors performed contralateral and ipsilateral transcallosal approaches to the lateral ventricle. Using the navigation system, they measured areas of exposure, surgical freedom, angles of attack, and angle of view to the surgical surface. Two clinical cases are described. RESULTS The exposed areas of the ipsilateral (mean [± SD] 313.8 ± 85.0 mm²) and contralateral (344 ± 87.73 mm²) interhemispheric approaches were not significantly different (p = 0.12). Surgical freedom and vertical angles of attack were significantly larger for the contralateral approach to the most midsuperior reachable point (p = 0.02 and p = 0.01, respectively) and to the posterosuperior (p = 0.02 and p = 0.04) and central (p = 0.04 and p = 0.02) regions of the lateral wall of the lateral ventricle. Surgical freedom and vertical angles of attack to central and anterior points on the floor of the lateral ventricle did not differ significantly with approach. The angle to the surface of the caudate head region was less steep for the contralateral (135.6° ± 15.6°) than for the ipsilateral (152.0° ± 13.6°) approach (p = 0.02). CONCLUSIONS The anterior contralateral interhemispheric transcallosal approach provided a more expansive exposure to the lower two-thirds of the lateral ventricle and striothalamocapsular region. In normal-sized ventricles, the foramen of Monro and the choroidal fissure were better visualized through the lateral ventricle ipsilateral to the craniotomy than through the contralateral approach.

Contralateral Anterior Interhemispheric Approach to Medial Frontal Arteriovenous Malformations: Surgical Technique and Results

BACKGROUND: Medial frontal arteriovenous malformations (AVMs) require opening the interhemispheric fissure and are traditionally accessed through an ipsilateral anterior interhemispheric approach (IAIA). The contralateral anterior interhemispheric approach (CAIA) flips the positioning with the midline still positioned horizontally for gravity retraction, but with the AVM on the upside and the approach from the contralateral, dependent side.

OBJECTIVE: To determine whether the perpendicular angle of attack associated with the IAIA converts to a more favorable parallel angle of attack with the CAIA.

METHODS: The CAIA was used in 6 patients with medial frontal AVMs. Patients and AVM characteristics, as well as pre- and postoperative clinical and radiographic data, were reviewed retrospectively.

RESULTS: Four patients presented with unruptured AVMs, with 5 AVMs in the dominant, left hemisphere. The lateral margin was off-midline in all cases, and average nidus size was 2.3 cm. All AVMs were resected completely, as confirmed by postoperative catheter angiography. All patients had good neurological outcomes, with either stable or improved modified Rankin Scores at last follow-up.

CONCLUSIONS: This study demonstrates that the CAIA is a safe alternative to the IAIA for medial frontal AVMs that extend 2 cm or more off-midline into the deep frontal white matter. The CAIA aligns the axis of the AVM nidus parallel to the exposure trajectory, brings its margins in view for circumferential dissection, allows gravity to deliver the nidus into the interhemispheric fissure, and facilitates exposure of the lateral margin for the final dissection, all without resecting or retracting adjacent normal cortex.

Thalamic cavernous malformations

Cavernous malformations of the thalamus represent a particularly complex subset of cavernous malformations because of the highly eloquent nature of the involved tissue and their deep location. The decision about whether to operate on any individual lesion depends on the specific location of the lesion within the thalamus, the nature of the patient's symptoms, and the patient's history. When surgery is recommended, the approach must be chosen carefully. Each part of the thalamus is reached by a different surgical approach. These approaches include the orbitozygomatic approach to the anteroinferior thalamus, the anterior interhemispheric transcallosal approach to the medial thalamus, the anterior contralateral interhemispheric transcallosal approach to the lateral thalamus, the posterior interhemispheric transcallosal approach to the posterosuperior thalamus, the parieto-occipital transventricular approach to the lateral posteroinferior thalamus, and the suboccipital supracerebellar infratentorial/transtentorial approach to the medial posteroinferior thalamus. Careful attention to safe entry zones and image guidance can allow safe removal of these lesions when necessary.

Clinical course of untreated thalamic cavernous malformations: hemorrhage risk and neurological outcomes

OBJECTIVE The natural history of cerebral cavernous malformations (CMs) has been widely studied, but the clinical course of untreated thalamic CMs is largely unknown. Hemorrhage of these lesions can be devastating. The authors undertook this study to obtain a prospective hemorrhage rate and provide a better understanding of the prognosis of untreated thalamic CMs. METHODS This longitudinal cohort study included patients with thalamic CMs who were diagnosed between 2000 and 2015. Clinical data were recorded, radiological studies were extensively reviewed, and follow-up evaluations were performed. RESULTS A total of 121 patients were included in the study (56.2% female), with a mean follow-up duration of 3.6 years. The overall annual hemorrhage rate (subsequent to the initial presentation) was calculated to be 9.7% based on the occurrence of 42 hemorrhages over 433.1 patient-years. This rate was highest in patients (n = 87) who initially presented with hemorrhage and focal neurological deficits (FNDs) (14.1%) (χ² = 15.358, p < 0.001), followed by patients (n = 19) with hemorrhage but without FND (4.5%) and patients (n = 15) without hemorrhage regardless of symptoms (1.2%). The initial patient presentations of hemorrhage with FND (hazard ratio [HR] 2.767, 95% CI 1.336-5.731, p = 0.006) and associated developmental venous anomaly (DVA) (HR 2.510, 95% CI 1.275-4.942, p = 0.008) were identified as independent hemorrhage risk factors. The annual hemorrhage rate was significantly higher in patients with hemorrhagic pres entation at diagnosis (11.7%, p = 0.004) or DVA (15.7%, p = 0.002). Compared with the modified Rankin Scale (mRS) score at diagnosis (mean 2.2), the final mRS score (mean 2.0) was improved in 37 patients (30.6%), stable in 59 patients (48.8%), and worse in 25 patients (20.7%). Lesion size (odds ratio [OR] per 0.1 cm increase 3.410, 95% CI 1.272-9.146, p = 0.015) and mRS score at diagnosis (OR per 1 point increase 3.548, 95% CI 1.815-6.937, p < 0.001) were independent adverse risk factors for poor neurological outcome (mRS score ≥ 2). Patients experiencing hemorrhage after the initial ictus (OR per 1 ictus increase 6.923, 95% CI 3.023-15.855, p < 0.001) had a greater chance of worsened neurological status. CONCLUSIONS This study verified the adverse predictors for hemorrhage and functional outcomes of thalamic CMs and demonstrated an overall annual symptomatic hemorrhage rate of 9.7% after the initial presentation. These findings and the mode of initial presentation are useful for clinicians and patients when selecting an appropriate treatment, although the tertiary referral bias of the series should be taken into account.

Clinical considerations and surgical approaches for low-grade gliomas in deep hemispheric locations: thalamic lesions

BACKGROUND

Tumors with epicenter in the thalamus occur in about 4 % of pediatric brain tumors. The histological diagnosis is mainly gliomas. Among them, low-grade glioma (LGG) constituted of a significant entity of the tumors (Cuccia et al., Childs Nerv Syst 13:514-521, 1997; Puget et al., J Neurosurg 106:354-362, 2007; Bernstein et al., J Neurosurg 61:649-656, 1984; Bilginer et al., Childs Nerv Syst 30:1493-1498, 2014). Since Kelly's report in 1989, >90 % resection of thalamic tumors were achieved in reported series (Ozek and Ture, Childs Nerv Syst 18:450-6, 2002; Villarejo et al., Childs Nerv Syst 10:111-114, 1994; Moshel et al., Neurosurgery 61:66-75, 2007; Albright, J Neurosurg 100(5 Suppl Pediatrics): 468-472, 2004; Kelly, Neurosurgery 25:185-195, 1989; Drake et al., Neurosurgery 29: 27-33, 1991).

MATERIALS AND METHODS

Sixty-nine cases of thalamic tumors in children were retrospectively reviewed. There were 25 cases of LGGs. We analyzed our experience and correlated it with reported series.

RESULTS

Summing up of 4 reported series and the present series, there were 267 cases of thalamic tumors in children. Among these tumors, 107 (40.1 %) were LGGs and 91 (34.1 %) were low-grade astrocytomas (LGAs). In the present series, all of the 25 LGGs were LGAs that consisted of 11 pilocytic astrocytomas (PAs) and 14 diffuse astrocytomas (DAs). Six cases received biopsy sampling only. The remaining 19 cases received different degrees of surgical resection via several approaches. Radical (>90 %) resection was achieved better in PAs comparing with DAs. There was no operative mortality. Two patients had increased neurological deficits. In a mean follow-up period of 11.9 years, three patients died of tumor progression and one patient died of anaplastic change. The 5- and 10-year overall survival (OS) was 87.1 and 87.1 %, respectively.

CONCLUSION

Thalamic LGGs are mainly LGAs and are indolent. The rate of >90 % resection was relatively low in the present series. By applying contemporary diagnostic MRI studies, surgical facilities, and appropriate approaches in selective cases, we may try maximum neuroprotective radical (>90 %) resection.

Occipital transtentorial/falcine approach, a "cross-court" trajectory to accessing contralateral posterior thalamic lesions: case report

Surgical treatment of lesions in the posterior thalamus, especially those extending laterally, is technically challenging because of a deep surgical field, narrow operative corridor, and the surrounding critical neurovascular structures. The authors describe an occipital transtentorial/falcine approach (OTFA) that was successfully used in the treatment of a cavernous malformation (CM) extending laterally from thalamus to midbrain. A 40-year-old man complained of progressive right hemiparesis and numbness. Radiological evaluation revealed a large CM in the left thalamus, surfacing on the pulvinar thalami, and extending 4 cm laterally from the midline. In addition to the usual procedures of a right-sided occipital transtentorial approach, the authors incised the falx cerebri to expand the operative corridor to the left thalamus. They achieved generous exposure of the left thalamus through a "cross-court" oblique trajectory while avoiding excessive retraction on the occipital lobe. The CM was completely removed, and no newly developed or worsening deficits were detected postoperatively. To better understand the OTFA and its application, the authors performed a cadaveric dissection. The OTFA provides increased exposure of the posterior thalamus without cortical incision and facilitates lateral access to this area through the "cross-court" operative corridor. This approach adds to the armamentarium for neurosurgeons treating thalamic lesions.

[The paramedian supracerebellar transtentorial approach to the mediobasal temporal region]

The mediobasal temporal region (MTR) is located near the brain stem and surrounded by the eloquent neurovascular structures. The supracerebellar transtentorial approach (STA) is safe access to the posterior MTR structures, however its use for resection of anterior MTR lesions still remains controversial. The article describes the technique and outcome of surgery for different MTR structures using STA.

MATERIAL AND METHODS

The paramedian STA was used in 18 patients (13 females and 5 males) for 7 years. Ten patients presented with glial MTR tumors, 3 patients with cavernomas, 2 patients with arteriovenous malformations (AVMs), 2 patients with intraventricular meningiomas, and 1 patient with mesial temporal sclerosis. The patient age ranged from 19 to 57 years. In 10 cases, lesions were localized on the left. Epilepsy was the leading symptom in 14 cases. Patients underwent preoperative high-resolution MRI, electroencephalography video monitoring before and after surgery, intraoperative corticography (if necessary), and postoperative CT and MRI.

RESULTS

Lesions were located in the anterior third of MTR in 5 patients, in the anterior and middle thirds in 2 patients, in the middle third in 5 patients, in the middle and posterior thirds in 2 patients, in the posterior third in 1 patient, in the anterior, middle, and posterior thirds in 1 patient, and in the ventricular triangle area in 2 patients. In all patients with intraventricular tumors, AVMs, and cavernous malformations and in 8 patients with glial MTR tumors, the lesions were totally resected. Two patients with intracerebral tumors underwent subtotal resection. A patient with intractable epilepsy and mesial temporal sclerosis underwent resection of the anterior two-thirds of the hippocampus and parahippocampal gyrus and, partially, amygdala using intraoperative corticography. There was no surgical mortality; 2 patients developed a transient neurological deficit, and 1 patient had a cerebellar hematoma that was successfully removed during surgery.

CONCLUSION

STA enables resection of lesions localized in all parts of the MTR, without damage to the surrounding nerve and vascular structures.

Giant cavernous malformation in the ventrolateral midbrain with extension into the thalamus: a case report of a paramedian supracerebellar transtentorial approach

Cavernous malformations (CMs) of the midbrain and thalamus are relatively rare and particularly difficult to be resected given their location in eloquent tissues. Here, we report a case of a 14-year-old boy who experienced repeated and progressive right hemiparesis. Image examinations showed a gradually enlarged CM originated in the left ventrolateral midbrain extending to the left thalamus with repeated hemorrhage. By performing a paramedian supracerebellar transtentorial approach, the CM was totally removed, and the patient recovered without any new neurological deficit. The authors' experience suggests that this approach is eminent in treating giant lesions involving the ventrolateral midbrain and thalamus.