Link, Michael J.

ObjectiveTo ascertain the relationship among vestibular schwannoma (VS) tumor volume, growth, and hearing loss.Study DesignRetrospective cohort study.SettingSingle tertiary center.Subjects and MethodsAdults with observed VS and serviceable hearing at diagnosis were included. The primary outcome was the development of nonserviceable hearing as estimated using the Kaplan‐Meier method. Associations of tumor volume with baseline hearing were assessed using Spearman rank correlation coefficients. Associations of volume and growth with the development of nonserviceable hearing over time were assessed using Cox proportional hazards models and summarized with hazard ratios (HRs).ResultsOf 230 patients with VS and serviceable hearing at diagnosis, 213 had serial volumetric tumor data for analysis. Larger tumor volume at diagnosis was associated with increased pure‐tone average (PTA) (P <. 001) and decreased word recognition score (WRS) (P =. 014). Estimated rates of maintaining serviceable hearing at 6 and 10 years following diagnosis were 67% and 49%, respectively. Larger initial tumor volume was associated with development of nonserviceable hearing in a univariable setting (HR for 1‐cm3 increase: 1.36, P =. 040) but not after adjusting for PTA and WRS. Tumor growth was not significantly associated with time to nonserviceable hearing (HR, 1.57; P =. 14), although estimated rates of maintaining serviceable hearing during observation were poorer in the group that experienced growth.ConclusionLarger initial VS tumor volume was associated with poorer hearing at baseline. Larger initial tumor volume was also associated with the development of nonserviceable hearing during observation in a univariable setting; however, this association was not statistically significant after adjusting for baseline hearing status.

AbstractObjective The objective of this study is to describe the clinical presentation, tumor characteristics, natural history, and treatment patterns of sinonasal osteosarcoma.Methods Fourteen patients who had been treated for osteosarcoma of the nasal cavity and paranasal sinuses at a tertiary care center were reviewed. In addition, a systematic review of the literature for osteosarcoma of the sinonasal cavity was performed.Results In a systematic review, including 14 patients from the authors' institution, 53 total studies including 88 patients were assessed. Median follow-up was 18 months (interquartile range: 8–39 months). The most common presenting symptoms were facial mass or swelling (34%), and nasal obstruction (30%). The most common paranasal sinus involved by tumor was the maxillary sinus (64%), followed by the ethmoid sinuses (52%). The orbit (33%), dura (13%) and infratemporal fossa (10%) were the most common sites of local invasion. The majority of patients underwent surgery followed by adjuvant therapy (52.4%). Increasing age was associated with decreased overall survival rate (unit risk ratio [95% confidence interval (CI)] = 1.02 [1.003–1.043]; p = 0.0216) and T4 disease was associated with decreased disease-specific survival rate (hazard ratio [HR] = 2.87; p = 0.0495). The 2- and 5-year overall survival rates were 68 and 40%, respectively, while 2- and 5-year disease-specific survival rates were 71% and 44%, respectively.Conclusion Sinonasal osteosarcomas are uncommon tumors and can pose a significant therapeutic challenge. Increasing age and T4 disease are associated with worse prognosis. This disease usually warrants consultation by a multidisciplinary team and consideration of multimodality therapy.

Abstract Systematic reviews and meta-analyses in the neurosurgical literature have surged in popularity over the last decade. It is our concern that, without a renewed effort to critically interpret and appraise these studies as high or low quality, we run the risk of the quality and value of evidence-based medicine in neurosurgery being misinterpreted. Correspondingly, we have outlined 4 major domains to target in interpreting neurosurgical systematic reviews and meta-analyses based on the lessons learned by a collaboration of clinicians and academics summarized as 4 pearls. The domains of (1) heterogeneity, (2) modeling, (3) certainty, and (4) bias in neurosurgical systematic reviews and meta-analyses were identified as aspects in which the authors’ approaches have changed over time to improve robustness and transparency. Examples of how and why these pearls were adapted were provided in areas of cranial neuralgia, spine, pediatric, and neuro-oncology to demonstrate how neurosurgical readers and writers may improve their interpretation of these domains. The incorporation of these pearls into practice will empower neurosurgical academics to effectively interpret systematic reviews and meta-analyses, enhancing the quality of our evidence-based medicine literature while maintaining a critical focus on the needs of the individual patients in neurosurgery.

A 60-year-old man with a history of four prior operations for a left cerebellar/middle cerebellar peduncle hemangioblastoma presented with hearing loss, imbalance, and ataxia (de la Monte and Horowitz, 1989). Magnetic resonance imaging (MRI) demonstrated a 3-cm cystic mass with heterogeneous enhancement in the same location. We resected the mass via reopening of the retrosigmoid approach (Lee et al., 2014). Left cranial nerves IV, V, VII, VIII, IX, X, and XI were all well identified and preserved, and feeding arteries from the brainstem were meticulously coagulated and transected without violating the tumor-brainstem interface (Chen et al., 2013). Preoperative embolization greatly aided safe resection of the mass, whose pathology revealed recurrence of hemangioblastoma (Eskridge et al., 1996; Kim et al., 2006; Sakamoto et al., 2012). The video can be found here: https://youtu.be/3mZgY15xOZc .

Cavernous malformations (CMs) are low-pressure, focal, vascular lesions that may occur within the brainstem and require treatment, which can be a substantial challenge. Herein, we demonstrate the surgical resection of a hemorrhaged brainstem CM through a posterior petrosectomy approach. After dissection of the overlying vascular and meningeal structures, a safe entry zone into the brainstem is identified based on local anatomy and intraoperative neuronavigation. Small ultrasound probes can also be useful for obtaining real-time intraoperative feedback. The CM is internally debulked and resected in a piecemeal fashion through an opening smaller than the CM itself. As brainstem CMs are challenging lesions, knowledge of several surgical nuances and adoption of careful microsurgical techniques are requisite for success. The video can be found here: https://youtu.be/szB6YpzkuCo .

Abstract Endovascular therapy is the primary treatment for the majority of tentorial dural arteriovenous fistulas (dAVF). Surgical occlusion is an effective alternative when embolization is not possible. This video demonstrates microsugical occlusion of a right-sided tentorial dAVF in a symptomatic 45-yr-old male. The dAVF was fed directly by meningohypophyseal trunk. Venous drainage was retrograde through the sphenoparietal sinus, superficial sylvian vein, vein of Labee, and transverse sinus. The patient underwent a right-sided pterional craniotomy; the sylvian fissure was widely opened. Subarachoid dissection was performed until a large arterialized draining vein was identified exiting dura subtemporally. Intraoperative indocyanine green angiography confirmed the fistulous site and the draining vein was occluded and divided. The patient remained neurologically intact after surgery. Immediate angiography demonstrates complete occlusion of the dAVF. This video demonstrates the surgical access obtained through a transylvian approach for this tentorial dAVF. Occlusion of the draining vein, with or without resection of the fistula, is enough to permanently treat these lesions.

Abstract Objective This study was aimed to provide a key update to the seminal works of Prof. Albert L. Rhoton Jr., MD, with particular attention to previously unpublished insights from the oral tradition of his fellows, recent technological advances including endoscopy, and high-dynamic range (HDR) photodocumentation, and, local improvements in technique, we have developed to optimize efficient neuroanatomic study. Methods Two formaldehyde-fixed cadaveric heads were injected with colored latex to demonstrate step-by-step specimen preparation for microscopic or endoscopic dissection. One formaldehyde-fixed brain was utilized to demonstrate optimal three-dimensional (3D) photodocumentation techniques. Results Key steps of specimen preparation include vessel cannulation and securing, serial tap water flushing, specimen drainage, vessel injection with optimized and color-augmented latex material, and storage in 70% ethanol. Optimizations for photodocumentation included the incorporation of dry black drop cloth and covering materials, an imaging-oriented approach to specimen positioning and illumination, and single-camera stereoscopic capture techniques, emphasizing the three-exposure-times-per-eye approach to generating images for HDR postprocessing. Recommended tools, materials, and technical nuances were emphasized throughout. Relative advantages and limitations of major 3D projection systems were comparatively assessed, with sensitivity to audience size and purpose specific recommendations. Conclusion We describe the first consolidated step-by-step approach to advanced neuroanatomy, including specimen preparation, dissection, and 3D photodocumentation, supplemented by previously unpublished insights from the Rhoton fellowship experience and lessons learned in our laboratories in the past years such that Prof. Rhoton's model can be realized, reproduced, and expanded upon in surgical neuroanatomy laboratories worldwide.

Objective: The majority of research influencing our understanding of vestibular schwannoma (VS) comes from large tertiary referral centers, and as a consequence, is inherently prone to referral bias. The objective of the current study was to characterize tertiary referral center bias in VS research. Study design: Single-institution retrospective clinical, audiometric, and radiologic review. Setting: One tertiary referral center. Patients: One hundred twenty-three patients with sporadic VS treated at our institution, consisting of a local cohort of all 41 VS patients residing in the same US county as our medical center and a referral cohort of 82 patients from outside counties matched 2:1 based on age, sex, and year of diagnosis. Intervention: Surgical resection, stereotactic radiosurgery (SRS), observation. Main outcome measures: Clinical manifestations, audiometric and radiologic findings, elected treatment modality. Results: Local patients had significantly longer follow-up after initial presentation compared to referral patients (median 4.0 vs 2.2 yr; p = 0.007). Referral patients were significantly less likely to have an incidental VS diagnosis (1% vs. 29%; p < 0.001) and presented with worse symptomatology such as hearing loss (80% vs. 54%; p = 0.002), dizziness (72% vs. 44%; p = 0.002), headache (29% vs. 15%; p = 0.075), and other cranial nerve dysfunction (11% vs. 0%; p = 0.029). Audiometrically, referral patients had significantly poorer word recognition scores at presentation (median 70% vs. 90%; p = 0.043). Local patients were more likely to have tumors confined to the IAC compared with referral patients, and had significantly smaller tumors when restricted to this region (median 4.0 vs 6.5 mm; p = 0.005). Referral patients were significantly more likely to undergo definitive management with either radiosurgery or microsurgery following primary evaluation compared to local patients (48% vs. 24%; p = 0.013). Conclusion: These data suggest that the majority of existing literature surrounding VS likely suffers from referral bias, whereby disease characteristics and management decisions are distinct from that of the general VS patient population.

Objective:To ascertain long-term hearing outcomes in patients with serviceable hearing following microsurgical resection of sporadic vestibular schwannoma (VS).Study Design:Retrospective cohort.Setting:Tertiary academic referral center.Patients:Forty-three adult subjects with unilateral sporadic VS who had serviceable hearing (American Academy of Otolaryngology–Head and Neck Surgery [AAO-HNS] class A or B) on initial postoperative audiogram following microsurgical resection between 2003 and 2016 with a minimum of two postoperative audiograms available for review.Intervention:Surgical treatment with a retrosigmoid or middle cranial fossa approach.Main Outcome Measure:Rate of maintaining serviceable hearing, as estimated using the Kaplan–Meier method, in accordance with the 1995 and 2012 AAO-HNS guidelines on reporting hearing outcomes.Results:The median immediate postoperative pure-tone average (PTA) and word recognition score (WRS) were 31 dB and 95%, respectively. At last follow-up, the median PTA was 38 dB with a median change of 5 dB from initial postoperative audiogram, and the median WRS was 90% with a median change of 0% from initial postoperative audiogram. Eight patients developed non-serviceable hearing at a median of 4.1 years following microsurgical resection (interquartile range, 2.9–7.0). The median duration of hearing follow-up for the 35 patients who maintained serviceable hearing was 3.1 years (interquartile range, 2.2–7.5). Tumor control was achieved in 41 (95%) patients. The rate of maintaining serviceable hearing at 5 years was 81%.Conclusion:Microsurgical resection provides excellent tumor control and durable long-term hearing in those with AAO-HNS class A or B hearing postoperatively. The paradigm of proactive microsurgical resection—when the tumor is small and hearing is good—hinges on the surgeon's ability to preserve residual hearing in a very high percentage of cases at or near preoperative hearing levels to maintain an advantage over conservative observation with regard to long-term hearing preservation.

OBJECTIVEStereotactic radiosurgery (SRS) is an accepted treatment option for patients with benign parasellar tumors. Here, the authors’ objective was to determine the risk of developing new or progressive internal carotid artery (ICA) stenosis or occlusion after single-fraction SRS for cavernous sinus meningioma (CSM) or growth hormone–secreting pituitary adenoma (GHPA).METHODSThe authors queried their prospectively maintained registry for patients treated with single-fraction SRS for CSM or GHPA in the period from 1990 to 2015. Study criteria included no prior irradiation and ≥ 12 months of post-SRS radiological follow-up. Pre-SRS grading of ICA involvement was applied according to the 1993 classification schemes of Hirsch for CSM or Knosp for GHPA.RESULTSThe authors conducted a retrospective review of 283 patients, 155 with CSMs and 128 with GHPAs. Ninety-three (60%) CSMs were Hirsch category 2 and 3 tumors; 97 (76%) GHPAs were Knosp grade 2–4 tumors. Median follow-up after SRS was 6.6 years (IQR 1–24.9 years). No GHPA or category 1 CSM developed ICA stenosis or occlusion. Three (5.2%) patients with category 2 CSMs had asymptomatic ICA stenosis (n = 2) or occlusion (n = 1); 1 (1.1%) category 2 CSM patient had transient ischemic symptoms. Five (14.3%) category 3 CSMs progressed to ICA occlusion (4 asymptomatic, 1 symptomatic). The median time to stenosis/occlusion was 4.8 years (IQR 1.8–7.6). Five- and 10-year risks of ICA stenosis/occlusion in category 2 and 3 CSM patients were 7.5% and 12.4%, respectively. Five- and 10-year risks of ischemic stroke from ICA stenosis/occlusion in category 2 and 3 CSM patients were both 1.2%. Multivariate analysis showed patient age (HR 0.92, 95% CI 0.86–0.98, p = 0.01), meningioma pathology (HR and 95% CI not defined, p = 0.03), and pre-SRS carotid category (HR 4.51, 95% CI 1.77–14.61, p = 0.004) to be associated with ICA stenosis/occlusion. Internal carotid artery stenosis/occlusion was not related to post-SRS tumor growth (HR and 95% CI not defined, p = 0.41).CONCLUSIONSNew or progressive ICA stenosis/occlusion was common after SRS for CSM but was not observed after SRS for GHPA, suggesting a tumor-specific mechanism unrelated to radiation dose. Pre-SRS ICA encasement or constriction increases the risk of ICA stenosis/occlusion; however, the risk of ischemic complications is very low.