Sughrue, Michael E.

BACKGROUND: Intraoperative neuromonitoring (IONM) has become vital in the management of vestibular schwannoma (VS) with the paradigm shift from tumor eradication to functional preservation. Several facial nerve (FN) monitoring strategies have been explored over the past few decades ranging from free-running electromyography, direct nerve stimulation, continuous nerve stimulation, facial motor evoked potentials, blink reflex, and others. Hearing preservation surgery is guided primarily by far-field auditory brainstem response and real-time cochlear nerve action potentials. Given the heterogeneity in tumor and patient factors, it remains very difficult to accurately predict cranial nerve outcomes, regardless of the monitoring strategy. OBJECTIVE: To critically appraise literature regarding IONM during VS surgery and update the previous evidence-based clinical practice guideline. METHODS: This is a systematic review of the literature, incorporating articles from March 2015 to May 2022. Literature published before 2015 that would have been included in the previous Congress of Neurological Surgeons guideline was not searched again in this update. RESULTS: FN monitoring provides better functional outcomes compared with anatomic dissection alone and may guide the extent of tumor resection. While facial motor evoked potentials and free-running electromyography can provide continuous noninvasive FN monitoring, there are insufficient data to determine which more strongly correlates with facial function outcomes. Both electrophysiological data and tumor size correlate with facial function outcomes. The ideal hearing monitoring strategy remains unclear as there are insufficient data comparing cochlear nerve action potentials with far-field auditory brainstem response. All studies were graded as Class III evidence. CONCLUSION: IONM should be used in all VS cases. While the optimal FN and hearing monitoring strategy remains elusive, available data support the use of a combination of strategies, including preoperative tumor size, to maximize sensitivity and specificity. There remains a significant need for high-quality comparative studies to determine which intraoperative monitoring scheme can provide intraoperative guidance and predict postoperative outcome. The full guideline can be seen online at https://www.cns.org/guidelines/treatment-adults-vestibular-schwannoma/3-intraoperative-cranial-nerve-monitoring-in-manag

Abstract BACKGROUND Laser interstitial thermal therapy (LITT) is being used for the treatment of recurrent glioblastoma multiforme (GBM). Lesions can be treated using 1 or multiple LITT fibers depending on the preference of surgeons. Usually, more fibers are needed for coverage of larger tumors. OBJECTIVE To investigate and analyze how tumor size affected the number of LITT fibers used. METHODS This is a retrospective review of patients undergoing treatment of recurrent GBM. Patients were treated with up to 4 LITT fibers for adequate tumor coverage. Patient demographics, tumor characteristics, length of stay, complications, and biopsy results were recorded. RESULTS A total of 43 cases were treated using LITT, and of these cases, 31 consisted of contiguous lesions. We used more fibers to treat larger tumor volumes. On average, for each 5 cc of tumor volume, a fiber was added for proper coverage ( P = .554). Complications and length of stay were similar across the groups ( P = .378, P = .941). CONCLUSION LITT can be used for the treatment of recurrent GBM. For each 5 cc of tumor volume, a LITT fiber can be added to the treatment plan.

Abstract TARGET POPULATION Adults diagnosed with vestibular schwannomas. QUESTION 1 What is the prognostic significance of Antoni A vs B histologic patterns in vestibular schwannomas? RECOMMENDATION No recommendations can be made due to a lack of adequate data. QUESTION 2 What is the prognostic significance of mitotic figures seen in vestibular schwannoma specimens? RECOMMENDATION No recommendations can be made due to a lack of adequate data. QUESTION 3 Are there other light microscopic features that predict clinical behavior of vestibular schwannomas? RECOMMENDATION No recommendations can be made due to a lack of adequate data. QUESTION 4 Does the KI-67 labeling index predict clinical behavior of vestibular schwannomas? RECOMMENDATION No recommendations can be made due to a lack of adequate data. QUESTION 5 Does the proliferating cell nuclear antigen labeling index predict clinical behavior of vestibular schwannomas? RECOMMENDATION No recommendations can be made due to a lack of adequate data. QUESTION 6 Does degree of vascular endothelial growth factor expression predict clinical behavior of vestibular schwannomas? RECOMMENDATION No recommendations can be made due to a lack of adequate data. The full guideline can be found at: https://www.cns.org/guidelines/guidelines-management-patients-vestibular-schwannoma/chapter_6.

Abstract Please see the full-text version of this guideline (https://www.cns.org/guidelines/guidelines-management-patients-vestibular-schwannoma/chapter_8) for the target population of each recommendation listed below. QUESTION 1 What surgical approaches for vestibular schwannomas (VS) are best for complete resection and facial nerve (FN) preservation when serviceable hearing is present? RECOMMENDATION There is insufficient evidence to support the superiority of either the middle fossa (MF) or the retrosigmoid (RS) approach for complete VS resection and FN preservation when serviceable hearing is present. QUESTION 2 Which surgical approach (RS or translabyrinthine [TL]) for VS is best for complete resection and FN preservation when serviceable hearing is not present? RECOMMENDATION There is insufficient evidence to support the superiority of either the RS or the TL approach for complete VS resection and FN preservation when serviceable hearing is not present. QUESTION 3 Does VS size matter for facial and vestibulocochlear nerve preservation with surgical resection? RECOMMENDATION Level 3: Patients with larger VS tumor size should be counseled about the greater than average risk of loss of serviceable hearing. QUESTION 4 Should small intracanalicular tumors (<1.5 cm) be surgically resected? RECOMMENDATION There are insufficient data to support a firm recommendation that surgery be the primary treatment for this subclass of VSs. QUESTION 5 Is hearing preservation routinely possible with VS surgical resection when serviceable hearing is present? RECOMMENDATION Level 3: Hearing preservation surgery via the MF or the RS approach may be attempted in patients with small tumor size (<1.5 cm) and good preoperative hearing. QUESTION 6 When should surgical resection be the initial treatment in patients with neurofibromatosis type 2 (NF2)? RECOMMENDATION There is insufficient evidence that surgical resection should be the initial treatment in patients with NF2. QUESTION 7 Does a multidisciplinary team, consisting of neurosurgery and neurotology, provides the best outcomes of complete resection and facial/vestibulocochlear nerve preservation for patients undergoing resection of VSs? RECOMMENDATION There is insufficient evidence to support stating that a multidisciplinary team, usually consisting of a neurosurgeon and a neurotologist, provides superior outcomes compared to either subspecialist working alone. QUESTION 8 Does a subtotal surgical resection of a VS followed by stereotactic radiosurgery (SRS) to the residual tumor provide comparable hearing and FN preservation to patients who undergo a complete surgical resection? RECOMMENDATION There is insufficient evidence to support subtotal resection (STR) followed by SRS provides comparable hearing and FN preservation to patients who undergo a complete surgical resection. QUESTION 9 Does surgical resection of VS treat preoperative balance problems more effectively than SRS? RECOMMENDATION There is insufficient evidence to support either surgical resection or SRS for treatment of preoperative balance problems. QUESTION 10 Does surgical resection of VS treat preoperative trigeminal neuralgia more effectively than SRS? RECOMMENDATION Level 3: Surgical resection of VSs may be used to better relieve symptoms of trigeminal neuralgia than SRS. QUESTION 11 Is surgical resection of VSs more difficult (associated with higher facial neuropathies and STR rates) after initial treatment with SRS? RECOMMENDATION Level 3: If microsurgical resection is necessary after SRS, it is recommended that patients be counseled that there is an increased likelihood of a STR and decreased FN function. The full guideline can be found at: https://www.cns.org/guidelines/guidelines-management-patients-vestibular-schwannoma/chapter_8.

During his lifetime and a career spanning 42 years, James Watson Kernohan made numerous contributions to neuropathology, neurology, and neurosurgery. One of these, the phenomenon of ipsilateral, false localizing signs caused by compression of the contralateral cerebral peduncle against the tentorial edge, has widely become known as “Kernohan's notch” and continues to bear his name. The other is a grading system for gliomas from a neurosurgical viewpoint that continues to be relevant for grading of glial tumors 60 years after its introduction. In this paper, the authors analyze these two major contributions in detail within the context of Kernohan's career and explore how they contributed to the development of neurosurgical procedures.