Citations

OBJECTIVE The floor of the third ventricle and the interpeduncular and prepontine regions represent challenging surgical targets. The expanded endoscopic endonasal approach (EEA) with pituitary gland (PG) transposition has been proposed to provide direct access to these anatomical regions. Through the years, different endoscopic PG transposition techniques have been studied and presented. The goal of this study was to compare the techniques, relevant anatomy, and surgical exposure of extradural, intradural, and interdural PG transposition techniques. METHODS Six formalin-fixed, latex-injected cadaveric head specimens were used to perform the EEA with extradural, unilateral interdural, and unilateral intradural PG transpositions. The interpeduncular and prepontine regions and the neurovascular structures located within these cisterns were carefully exposed and analyzed. The maximal cranial, caudal, and lateral accessible points within the surgical field were identified for each approach. Consequently, the relative craniocaudal and horizontal surgical axes were measured to quantify the extent of accessibility of each approach. RESULTS The extradural PG transposition technique provided the largest horizontal extensions and bilateral access to structures within the interpeduncular and prepontine regions; the mean horizontal axis was 17.9 (range 13.9–20.4) mm. The unilateral interdural PG transposition provided wider vertical exposure, with a mean craniocaudal axis of 16.2 (range 13.0–20.9) mm. In this approach, the surgical field was extended cranially above the ipsilateral mammillary body (MB). The unilateral intradural PG transposition provided a similar surgical exposure to the interdural approach, with a mean craniocaudal axis of 14.7 (range 12.9–15.8) mm. The approach required significant manipulation of the PG after opening both periosteal and meningeal dura layers. CONCLUSIONS The extradural PG transposition is indicated for lesions of the upper clivus region that extend bilaterally and do not have a cranial extension beyond the MBs. The inter- and intradural PG transpositions are beneficial for unilateral lesions that extend cranially to the MBs. Both techniques require coagulation of the ipsilateral inferior hypophyseal artery. The intradural technique requires more manipulation of the PG, while the interdural technique requires opening and access to the cavernous sinus. If needed, the intra- and interdural techniques can also be performed bilaterally.

Abstract We investigated the extent of access to Meckel's cave (MC) and the middle cranial fossa (MCF) protecting the internal carotid artery (ICA) using the retrosigmoid approach with endoscopic-assisted reverse anterior petrosectomy (EA-RAP). Five specimens were dissected using the limited and extended EA-RAP. Based on the bone removal of the internal acoustic meatus (IAM) and subarcuate fossa, exposure of the MC and ICA were statistically compared. The limited and extended EA-RAP allowed access to the medial and anterior MC (4 mm posterior to the first genu of the cavernous ICA, and 20 mm posterior to foramen rotundum [FR]). The access to the lateral MC varied with distance of 12 and 8 mm medial to the foramen ovale for the limited and extended EA-RAP, respectively. In the extended EA-RAP, the exposure of the ICA was gained by drilling with the 0-degree endoscope (3 mm) versus 45-degree endoscope (9 mm). The working distances from the midpoint of the IAM to the most medial point of the exposed ICA was 24 mm. The most lateral point of the exposed ICA varied between 0- and 45-degree endoscopes with a distance of 21 and 13 mm, respectively. A coronal plane from the posterior genu of the cavernous ICA and a sagittal plane to the common crus of the semicircular canals can define the area of MCF accessed by the EA-RAP. Drilling of the temporal bone should be carefully customized according to the patient and can be aided by endoscopic assistance for direct visualization to minimize the risk of injuries to ICA.

Objective To compare the utility of intraoperative electrically evoked auditory brainstem response (eABR) and electrically evoked stapedial reflex testing (eSRT) for cochlear nerve integrity monitoring during simultaneous translabyrinthine resection of vestibular schwannoma (VS) and cochlear implantation. Study design Historical cohort study. Setting Tertiary academic referral center. Patients Eleven patients (12 cases) who underwent translabyrinthine tumor resection with simultaneous placement of a standard, unmodified cochlear implant (CI). Intervention A CI placed at the beginning of the operation before tumor resection to facilitate intraoperative cochlear nerve monitoring through a CI-delivered electrical stimulus. Main outcome measure Correlation of intraoperative monitoring outcomes with postoperative CI performance. Results Among the 12 cases (median age, 47 years), eABR waveforms were present at the conclusion of tumor resection in 10, including 6 that achieved open set speech perception. Of the 2 cases with negative eABR, 1 achieved open set speech perception. By contrast, of the 8 cases with a positive eSRT response, 7 achieved open set speech perception. Of the 4 cases with a negative eSRT response, none achieved open set speech perception. The 3 cases that did not receive auditory stimulation included 2 with positive and 1 with negative eABR; all 3 had a negative eSRT response. Conclusions Intraoperative eSRT using an unmodified CI is a promising new method for monitoring the integrity of the cochlear nerve during simultaneous VS resection. eSRT response at the conclusion of tumor resection strongly correlated with CI open set speech capacity. Although still useful, eABR was less reliable at predicting postoperative hearing outcomes in this series.

AbstractObjectiveNeck metastases are a poor prognostic factor in olfactory neuroblastoma (ONB). Pathologic dural invasion (pathDI) may increase the risk of neck metastases due to invasion of dural lymphatics. We aim to evaluate the prognostic value of pathDI in predicting rates of neck metastases and recurrence using a large, multicenter database of ONB patients.Data sourcesRetrospective review of a prospective, multicenter database of electronic health records of all patients who presented with ONB between 2005 and 2021 at nine tertiary academic care centers within North America.Review methodsClinicopathologic features including modified Kadish staging systems, margin status, treatment modalities, Hyams grading, follow‐up time, and survival.ResultsOf 258 ONB patients, 189 patients met the inclusion criteria. The 10‐year neck recurrence‐free survival (neck‐RFS) rates were 85.7% (75.6‒97.3) and 61.8% (47.9‒79.8) for patients without and with pathDI, respectively (p = 0.018). Time‐to‐event multivariable regression analysis found pathDI to have an odds ratios of 9.7 (95% confidence interval [CI] 1.2–80.4, p = 0.04) for neck‐RFS and 9.5 for RFS at any site (95% CI 1.1–83.3, p = 0.04).ConclusionIn multivariable analysis, the presence of pathDI appears to be the strongest predictor of neck recurrence and recurrence at any site. Future studies exploring the benefit of elective neck dissection or radiation for patients with pathDI may impact disease management.

Abstract BACKGROUND BRAF pathway alterations are frequent in glial/neuroepithelial tumors. BRAF-targeted therapy with BRAF inhibitors (BRAFi) and/or MEK inhibitors (MEKi) has proven efficacy in clinical trials, though mainly enrolling pediatric patients. We sought to investigate real-world data for adult patients with BRAF-pathway mutant glial/neuroepithelial neoplasms treated with BRAFi/MEKi. METHODS Adults with BRAF-pathway mutated glial/neuroepithelial neoplasms treated with BRAFi/MEKi were retrospectively reviewed. RESULTS Five patients (n=4 female, median age at diagnosis 36) were identified (tumor types: glioblastoma n=1, high-grade astrocytoma with epithelioid features n=1, low-grade neuroepithelial tumor n=1, pilocytic astrocytoma n=1, pleomorphic xanthoastrocytoma n=1). Four had BRAF V600E and one had NF1 p.S2687Cfs*5 mutant tumors. Prior to targeted therapy initiation, patients underwent a median 2.4 treatments including surgery (n=4), radiation therapy (n=4), chemotherapy (temozolomide n=4; carboplatin/vincristine n=1). BRAF-targeted therapies included dabrafenib/trametinib (n=4), binimetinib/encorafenib (n=2), binimetinib (n=2). One NF1-mutant glioblastoma received binimetinib followed by binimetinib/bevacizumab. Median BRAFi/MEKi treatment was 15.2 months (range: 6-36 months). Toxicities included leukopenia (n=3), peripheral edema (n=1), reduced ejection fraction (n=1), skin rash (n=5), transaminitis (n=1) with all patients requiring dose reductions and 3 cases requiring discontinuation. Among patients where BRAFi/MEKi was discontinued due to toxicity, 2 received other treatments at progression, then switched to a different BRAFi/MEKi combination, which they tolerated (duration 6-10months). Best radiographic response was partial response, noted in 3 patients treated with dabrafenib/trametinib. Four patients remain alive and continue BRAFi/MEKi. CONCLUSIONS In this cohort of heavily-pretreated patients with glial/neuroepithelial neoplasms, BRAF-targeted therapy was associated with durable responses. Interestingly, two patients who were unable to tolerate one combination of BRAFi/MEKi were able to tolerate a different combination with sustained response. Our findings support ongoing use of BRAF targeted therapy for CNS tumors. Optimal timing and duration of treatment requires further prospective evaluation in adult patients.

BACKGROUND AND OBJECTIVE: Endoscopic endonasal approaches to treat cavernous sinus lesions require detailed knowledge of the origin, course, and anatomic variations of the branches of the cavernous internal carotid artery (cICA) because inadvertent avulsion can cause intraoperative ICA injury. We aim to study the origin and course of the branches of the cICA from an endoscopic endonasal perspective and relate these branches to surgically relevant anatomic references. METHODS: Sixty sides of 30 formalin-fixed specimens were dissected to identify the origin and course of cICA branches, including the inferolateral trunk (ILT), the meningohypophyseal trunk (MHT), anterior and inferior McConnell's capsular arteries (MCAs), and the superolateral trunk (SLT). RESULTS: The ILT and MHT were bilaterally in all specimens, whereas the anterior and inferior MCAs were identified in 28% and 25% of dissected sides, respectively. The SLT was only found in 3% of sides dissected. The MHT was the most proximal branch of the cICA, and its origin was an average of 8.9 mm anterior to the foramen lacerum and 3.8 mm superior to the sellar floor. The ILT was the second most proximal branch of the cICA, which originated 6.4 mm from the MHT on average. The anterior and inferior MCAs were present in 28% and 25% of specimens, respectively. The SLT, when present, was the second most proximal branch of the cICA, which originated at a mean height of 2.7 mm from the sellar floor. Overall, complete ILT and MHT were identified in 68% and 77% of cases, respectively. CONCLUSION: The MHT and ILT are constant branches of the cICA, with the MHT originating from the medial cICA posterior bend 4 mm superior to the sellar floor and 9 mm anterior to the foramen lacerum, whereas the ILT arises from the lateral horizontal cICA, 2.3 mm superior to the sellar floor and 6 mm anterior to the MHT.

OBJECTIVE Imaging surveillance with serial MRI, or a "wait-and-scan" approach, is a management option for patients with small or medium-sized vestibular schwannomas (VSs). Prior publications have indicated no distinct quality of life advantage to upfront treatment compared with initial wait-and-scan management. However, imaging surveillance is dependent on patient adherence to follow-up. In this study, the authors aimed to identify rates and predictors of patient loss to follow-up during wait-and-scan management of sporadic VS. METHODS A single-center study was conducted including all patients from 2013 to 2018 who had undergone upfront imaging surveillance of sporadic VS. Patient data were retrospectively obtained from the electronic medical record. Outcomes of interest included loss to follow-up unrelated to death and inconsistent adherence to imaging surveillance recommendations. Logistic regression analyses were conducted to evaluate factors associated with loss to follow-up. RESULTS Over a 6-year study period, 270 patients underwent initial imaging surveillance of a sporadic VS. The median tumor diameter was 8.6 mm (range 1–28.9 mm). At the time of censoring, 106 patients (39.3%) had received treatment, 157 (58.1%) had been advised to continue follow-up, and 7 (2.6%) had died of non–VS-related causes. In total, 73 patients (27.0%) were completely lost to follow-up prior to the first treatment or death. Additionally, 60 patients (22.2%) missed at least 1 MRI follow-up or imaging follow-up was delayed by more than 1 year. Multivariable logistic regression identified an out-of-state residence (OR 3.05, 95% CI 1.58–5.89, p = 0.0009) and a smaller tumor size (unit OR per 1-mm increase in size, OR 0.88, 95% CI 0.83–0.95, p = 0.0006) to be associated with loss to follow-up. Patients living ≥ 350 miles from the hospital or with tumors ≤ 3 mm at the time of initial clinic evaluation were most likely to be lost to follow-up. Only a smaller tumor size was associated with an increased risk of inconsistent imaging follow-up (unit OR per 1-mm increase in size, OR 0.92, 95% CI 0.87–0.98, p = 0.007). CONCLUSIONS Patients undergoing imaging surveillance of VS are at risk for loss to follow-up and inconsistent imaging surveillance. Patients with smaller tumors or those living farther away from the treating institution are at highest risk for being lost to follow-up.

OBJECTIVE Advances in surgical technology and microneurosurgery have led to increased utilization of so-called minimally invasive approaches, including the supraorbital eyebrow (SE) and minipterional (MPT) approaches for lesions involving the interpeduncular region. This study aimed to describe and compare anatomical landmarks, along with highlighting the advantages and disadvantages of the SE and MPT approaches to the interpeduncular region. METHODS Ten formalin-fixed, latex-injected cadaveric specimens were used to perform bilateral SE and MPT approaches to the interpeduncular region. The operative depth of each approach to key anatomical landmarks was measured. Forty-five axial thin-slice computed tomography studies were reviewed to calculate the operative angles, with consideration of the midline as a reference. A 3D interactive anatomical model generated through the photogrammetry scanning technique was described. RESULTS The depths of the operative corridors of the SE and MPT approaches to the interpeduncular fossa were 83.4 ± 1.8 mm and 67.7 ± 3.2 mm, respectively (p < 0.001). The mean angle of the MPT approach to the interpeduncular fossa was significantly wider than the one provided by the SE approach (39.9° ± 5.1° vs 28.4° ± 3.6°, p < 0.001). The interpeduncular region can consistently be accessed through the carotid-oculomotor triangle with the SE approach, as well as with the MPT approach. Furthermore, the SE route offered adequate access to the interpeduncular fossa through the opticocarotid triangle. The MPT route provided direct access to the upper prepontine cistern and anterior mesencephalic zone (AMZ). CONCLUSIONS The MPT approach provides a wider and shorter operative corridor and can be employed for lesions in the interpeduncular region with extension to the prepontine cistern and ventrolateral midbrain lesions requiring access through the AMZ. The SE approach is better suited for ventromedial midbrain lesions requiring access via the interpeduncular fossa safe entry zone. Additional studies analyzing these approaches in a clinical setting will help to delineate their reliability and efficacy.