Patel, Neil

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.

Objective: Intraoperative far-field auditory brainstem response (ABR) and direct cochlear nerve action potential monitoring using neural response imaging (NRI) are techniques for monitoring the cochlear nerve during vestibular schwannoma (VS) surgery. A new paradigm has developed where the cochlear nerve is anatomically preserved during tumor removal to facilitate cochlear implantation in select circumstances. This report describes the use of an unmodified commercial cochlear implant (CI) to elicit electrically-evoked direct cochlear nerve and far-field ABR monitoring to evaluate the status of the cochlear nerve during tumor resection in real time. Patients: Adult female with unilateral, sporadic VS. Intervention(s): Cochlear implantation followed by translabyrinthine resection of VS in single operation. Main Outcome Measures: During tumor resection intra-cochlear electrodes were used to deliver electrical stimulation and measure NRI or the cochlear nerve action potential. Electrically-evoked ABR (eABR) was measured using surface electrodes and wave V was monitored (far-field ABR) during surgery. Results: A 61-year-old female was evaluated for a unilateral, enlarging intracanalicular VS with asymmetric SNHL. The patient opted for microsurgery and due to her bilateral hearing loss was a candidate for CI. Cochlear implantation with an unmodified, commercially available lateral wall electrode was performed. The remainder of the approach and tumor resection was performed under continuous eABR and NRI monitoring. Gross total resection was achieved with intact eABR and NRI at the conclusion of the case. Changes in ABR and NRI consistently recovered after modifying dissection strategy. The patient reported auditory percepts with her cochlear implant postoperatively. Conclusions: This report demonstrates the feasibility of using real-time NRI and eABR with a CI to facilitate preservation of the cochlear nerve during VS microsurgery. Using this method to mitigate cochlear nerve trauma during microsurgery may preserve the option of CI for hearing rehabilitation.

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.

Objective: The etiology of sensorineural hearing loss (SNHL) in patients with jugular paraganglioma (JP) whose tumors lack inner ear fistulae or vestibulocochlear nerve involvement is unknown. Recent literature has proposed that occlusion of the inferior cochlear vein may be causative. Herein, we assess the association between radiologic involvement of the cochlear aqueduct (CA) and the development of SNHL. Study Design: Blinded, retrospective review of imaging and audiometry. Setting: Tertiary center. Patients: Adults with JP. Intervention(s): None. Main Outcome Measures: Asymmetric SNHL was assessed continuously as the difference in bone conduction pure-tone average (BCPTA) between ears and as a categorical variable (≥15 dB difference at two consecutive frequencies, or a difference in speech discrimination score of ≥15%). Involvement of the CA was considered present if there was evidence of medial T2 fluid signal loss, contrast enhancement, or bony erosion/expansion. Results: Of 30 patients meeting inclusion criteria, 15 (50%) had asymmetric SNHL. CA involvement was observed in 87% of patients with asymmetric SNHL compared with 13% in those with symmetric hearing (p = 0.0001). Univariate analysis demonstrated that age, sex, and tumor volume were not associated with asymmetric SNHL. The median difference in BCPTA between ears in patients with CA involvement was 21.3 dB HL compared to 1.2 dB HL in those without CA involvement (p < 0.0001). Regression analysis demonstrates that enhancement within the CA is associated with a BCPTA difference of 19.4 dB HL (p = 0.0006). Conclusions: Cochlear aqueduct involvement by JP is associated with SNHL in the absence of inner ear fistula, vestibulocochlear nerve involvement, or brainstem compression. Correlation with operative findings or histopathologic evidence of tumor involvement may validate this intriguing imaging finding.

Objective: Previous research has shown that tumor growth during observation of small-to-medium sized sporadic vestibular schwannomas (VSs) occurs almost exclusively within 3 to 5 years following diagnosis. This has led some to consider ending surveillance after this interval. This study seeks to characterize a cohort of patients with tumors that exhibited late growth. Study Design: Retrospective cohort study. Setting: Tertiary referral center. Patients: Adults with sporadic VSs who initially elected observation with serial magnetic resonance imaging (MRI) surveillance. Intervention(s): None. Main Outcome Measure(s): Linear tumor growth was measured in accordance with AAO-HNS reporting guidelines. Delayed growth was defined as growth ≥2 mm in linear diameter that was first detected 5 years or more from the initial MRI. Results: From a total of 361 patients, 172 experienced tumor growth during the interval of observation. Fourteen of these 172 patients (8.1%) experienced late growth occurring at 5 years or beyond. Among patients with delayed growth, the fastest growth rate after extended quiescence was 1.33 mm/yr, and the longest delay before tumor growth detection was 11.1 years. Additional treatment was recommended for six (42.9%) of the patients with delayed growth. Of 68 tumors that remained in the IAC, 11 (16.2%) demonstrated delayed growth. Of 66 tumors that presented in the CPA, 2 (3.0%) demonstrated delayed growth. Initial size was larger for tumors demonstrating early growth compared with those with delayed growth. For tumors within the IAC, those with early growth had a significantly higher median growth rate than those with delayed growth (1.40 vs. 0.45 mm/yr, p < 0.001). Conclusions: Delayed growth encompassed 8.1% of growing VSs and 3.9% of all observed tumors. Patients with delayed growth exhibited slower growth rates compared with those who were diagnosed with growth early in their observation course. These findings support the need for lifelong surveillance of untreated VSs given the possibility of clinically significant delayed growth. Increasing the time interval between MRI studies after 5 years is a reasonable concession to balance practicalities of cost and convenience with risk of delayed of tumor growth.

Objectives: Catecholamine-secreting jugular paragangliomas (JPs) represent a rare subset of head and neck paragangliomas that may present with hypertension, arrhythmia, or syncopal episodes. Subtotal resection to protect critical neurovascular structures may result in persistent catecholamine excess from residual tumor. Herein, we report our experience with stereotactic radiosurgery (SRS) for salvage treatment of catecholamine-secreting JP following subtotal microsurgical resection. Patients: Adult patients treated with SRS after subtotal microsurgical resection of catecholamine-secreting JP. Interventions: SRS. Main Outcome Measures: Post-treatment catecholamine and metanephrine levels, clinical outcomes, and tumor control. Results: Of 85 patients with JPs treated with primary or salvage radiosurgery between 1990 and 2017, 2 (2%) harbored nonmalignant secreting tumors. Patient 1 developed catecholamine excess with elevated norepinephrine (NE) at 475 mcg/24 hours (normal < 80 mcg/24 h). Following subtotal resection, she developed catecholamine excess with radiographic evidence of tumor growth and therefore underwent SRS. Three years post-SRS and beyond, catecholamine levels remained normalized (NE 62 mcg/24 h at 10 yr) and tumor volume remained stable on serial MRI studies over the 17-year follow-up period. Patient 2 developed symptomatic arrhythmia and was found to have a JP. Urine norepinephrine (NE) was elevated at 213 mcg/24 hours. She underwent nerve-sparing subtotal resection and upfront SRS was used to treat residual tumor. Twenty months following SRS, the area of residual JP had not enlarged in size and catecholamine levels remained normal (NE 46 mcg/24 h). Conclusions: Radiosurgery can be used in salvage treatment of catecholamine-secreting JP, providing durable tumor control and resolution of catecholamine excess. For patients with large catecholamine-secreting JP and normal lower cranial nerve function, aggressive nerve-sparing subtotal resection with adjuvant radiosurgery may offer a low-morbidity alternative to gross total resection. Further study of this subset of patients is warranted to substantiate these promising, yet preliminary findings.

OBJECTIVE The morbidity of gross-total resection of jugular paraganglioma (JP) is often unacceptable due to the potential for irreversible lower cranial neuropathy. Stereotactic radiosurgery (SRS) has been used at the authors’ institution since 1990 for the treatment of JP and other benign intracranial tumors. Conventional means of assessing tumor progression using linear measurements or elliptical approximations are imprecise due to the irregular shape and insinuating growth pattern of JP. The objective of this study was to assess long-term tumor control in these patients by using slice-by-slice 3D volumetric segmentation of serial MRI data. METHODS Radiographic data and clinical records were reviewed retrospectively at a single, tertiary-care academic referral center for patients treated from 1990 to 2017. Volumetric analyses by integration of consecutive tumor cross-sectional areas (tumor segmentation) of serial MRI data were performed. Tumor progression was defined as volumetric growth of 15% or greater over the imaging interval. Primary outcomes analyzed included survival free of radiographic and clinical progression. Secondary outcomes included new or worsened cranial neuropathy. RESULTS A total of 85 patients were treated with Gamma Knife radiosurgery (GKRS) for JP at the authors’ institution over the last 27 years. Sixty patients had pretreatment and serial posttreatment contrast-enhanced MRI follow-up suitable for volumetric analysis. A total of 214 MR images were analyzed to segment tumor images in a slice-by-slice fashion to calculate integral tumor volume. The median follow-up duration was 66 months (range 7–202 months). At 5 years the tumor progression-free survival rate was 98%. Three tumors exhibited progression more than 10 years after GKRS. Estimated survival free of radiographic progression rates (95% confidence interval [CI]; n = number still at risk) at 5, 10, and 15 years following radiosurgery were 98% (95% CI 94%–100%; n = 34), 94% (95% CI 85%–100%; n = 16), and 74% (95% CI 56%–98%; n = 6), respectively. One patient with tumor progression required treatment intervention using external beam radiation therapy, constituting the only case of clinical progression. Two patients (3%) without preexisting lower cranial nerve dysfunction developed new ipsilateral vocal fold paralysis following radiosurgery. CONCLUSIONS SRS achieves excellent long-term tumor control for JP without a high risk for new or worsened cranial neuropathy when used in primary, combined modality, or recurrent settings. Long-term follow-up is critical due to the potential for late radiographic progression (i.e., more than 10 years after SRS). As none of the patients with late progression have required salvage therapy, the clinical implications of this degree of tumor growth have yet to be determined.

Objectives To describe transnasal Eustachian tube (ET) occlusion with a liquid embolic solution for lateral skull base cerebrospinal fluid (CSF) leaks. Design A lateral skull base CSF fistula model was developed by the authors using fresh cadaveric heads. Using a transtympanic needle, regulated pressurized pigmented saline was continuously instilled into the middle ear space and visualized endoscopically in the nasopharynx. An angioembolization catheter was then placed through the cartilaginous ET orifice just medial to the bony ET. Under endoscopic and fluoroscopic guidance, a column of liquid embolic agent was deployed into the bony ET segment up to the middle ear space. Setting Tertiary care academic center. Participants Cadaveric specimens. Main Outcome Measures Cessation of CSF flow after occlusion at supraphysiologic pressures. Results In two cadavers, a CSF fistula model was developed and endoscopic visualization of irrigant flow into the nasopharynx was confirmed. Fluoroscopy provided adequate anatomic views of the ET and middle ear, in addition to dynamic views of embolization. Cessation of flow after occlusion was successfully achieved with pressures up to 25 mm Hg, which exceeds normal physiological intracranial pressure. Conclusion Eustachian tube occlusion with a liquid embolic solution is feasible in a novel cadaveric CSF leak model. In the future, this relatively short, straightforward procedure may become an outpatient alternative to manage intermittent or low-flow CSF fistulae following lateral skull base surgery.

Objectives/HypothesisWe sought to analyze key factors that influence the management of lateral skull base defects and implement an algorithm to improve outcomes of reconstruction.Study DesignRetrospective chart review.SettingSingle tertiary academic referral center.MethodsAdults who underwent temporal bone resection were included. Variables included tumor characteristics, ablative procedure, reconstructive method, and wound complications.ResultsSeventy‐one patients were studied. Lateral temporal bone resection was performed in 55 patients (77%), subtotal temporal bone resection in 14 (20%), and total petrosectomy in two (3%). Primary closure was achieved in 46 patients (35%), with rotational muscle flaps in 21 (46%). The pectoralis major myocutaneous flap (PMMF) was used in nine patients (13%) without major complications. Single‐stage free tissue transfer was undertaken in 10 patients (14%) with no flap failures. Primary closure was achieved in 16 of 32 of previously untreated cases (50%) compared to nine of 39 cases of previously treated disease (23%) (P = 0.03). Pedicled or free flaps were used in 18 of 39 cases of previously treated disease (46%) compared to three of 32 previously untreated cases (9%) (P < 0.001). Pedicled or free flaps were used in 13 of 22 cases (59%) in which partial or total auriculectomy was performed, whereas primary closure was achieved in 39 of 49 cases (80%) in which the pinna was preserved (P < 0.001).ConclusionAdvanced tumors that require adjuvant therapy, revision cases for recurrent disease, and cases involving auriculectomy warrant free flap or PMMF reconstruction, with the latter preferred in poor free flap candidates.Level of Evidence4. Laryngoscope, 126:1911–1917, 2016