Nassiri, Ashley M.

Abstract Epidermoid cysts are rare, benign lesions that result from inclusion of ectodermal elements during neural tube closure. 1 Cysts are composed of desquamated epithelial cells and restrict diffusion on magnetic resonance imaging (MRI). 2,3 Symptoms are attributable to anatomic location. 4,5 In this video, we illustrate the surgical treatment of an epidermoid cyst located in the right cerebellopontine angle, petrous apex, and Meckel's cave. The patient, a 33-yr-old female with right-sided V1 trigeminal hypoesthesia, underwent surveillance imaging for 2 yr. However, she developed progressive V1 and V2 trigeminal hypoesthesia and imaging revealed enlargement of the lesion. Therefore, surgical resection was pursued. The patient consented to the procedure. The patient underwent a right middle fossa craniotomy and anterior petrosectomy. After identifying the greater superficial petrosal nerve and cutting the middle meningeal artery as it exited foramen spinosum, Kawase's triangle was drilled, and the dura over Meckel's cave and the subtemporal dura were opened. The lesion was resected, taking care to preserve the trigeminal nerve and the basilar artery. A retrosigmoid craniotomy was then fashioned. The cyst and its capsule were dissected off the brainstem and cranial nerves utilizing natural corridors between the trigeminal and vestibulocochlear nerves as well as between the facial and lower cranial nerves. Gross total resection was confirmed on postoperative MRI, and she was discharged home on postoperative day 5. Three months after surgery, she underwent formal pinprick testing, which revealed 95% loss of sensation in V1, 20% loss in V2, and normal sensation in V3. Three-month postoperative MRI showed no residual tumor.

Objective: Active treatment of small- or medium-sized vestibular schwannoma during wait-and-scan management is currently recommended at most centers globally once growth is detected. The primary aim of the current study was to characterize the natural history of growing sporadic vestibular schwannoma during observation. Study Design: Cohort study. Setting: Four tertiary referral centers across the United States and Denmark. Patients: Patients with two prior MRI scans demonstrating ≥2 mm of linear growth who continued observational management. Intervention: Observation with serial imaging. Main Outcome Measure: Subsequent linear growth-free survival (i.e., an additional ≥2 mm of growth) following initial growth of ≥2 mm from tumor size at diagnosis. Results: Among 3,402 patients undergoing observation, 592 met inclusion criteria. Median age at initial growth was 66 years (IQR 59–73) for intracanalicular tumors (N = 65) and 62 years (IQR 54–70) for tumors with cerebellopontine angle extension (N = 527). The median duration of MRI surveillance following initial detection of tumor growth was 5.2 years (IQR 2.4–6.9) for intracanalicular tumors and 1.0 year (IQR 1.0–3.3) for cerebellopontine angle tumors. For intracanalicular tumors, subsequent growth-free survival rates (95% CI; number still at risk) at 1, 2, 3, 4, and 5 years following the initial MRI that demonstrated growth were 77% (67–88; 49), 53% (42–67; 31), 46% (35–60; 23), 34% (24–49; 17), and 32% (22–47; 13), respectively. For cerebellopontine angle tumors, subsequent growth-free survival rates were 72% (68–76; 450), 47% (42–52; 258), 32% (28–38; 139), 26% (21–31; 82), and 22% (18–28; 57), respectively. For every 1 mm increase in magnitude of growth from diagnosis to tumor size at detection of initial growth, the HRs associated with subsequent growth were 1.64 (95% CI 1.25–2.15; p < 0.001) for intracanalicular tumors and 1.08 (95% CI 1.01–1.15; p = 0.02) for cerebellopontine angle tumors. Conclusions: Growth detected during observation does not necessarily portend future growth, especially for slowly growing tumors. Because early treatment does not confer improved long-term quality of life outcomes, toleration of some growth during observation is justifiable in appropriately selected cases.

Objective: Reports using large brain tumor and cancer registries suggest that the incidence of vestibular schwannoma is considerably lower in the United States compared with other countries. The current study compares the incidence and disease characteristics of vestibular schwannoma within a large tertiary referral center's brain tumor and cancer registry using nationally mandated reporting protocols to disease incidence in the same population using an externally validated population-based consortium. Study Design: Population-based study spanning 1,945,007 person-years. Setting: Large tertiary referral center. Patients: Adults with sporadic vestibular schwannoma. Main Outcome Measure: Disease incidence rates from 2004 to 2016. Results: From 2004 to 2016, the incidence of vestibular schwannoma in the tumor registry was 1.3 per 100,000 person-years whereas the population-based cohort had an incidence of 4.4 per 100,000 person-years. From 2012 to 2016, the incidence in the tumor registry was 1.4 per 100,000 person-years compared with 5.2 in the population-based cohort. Patients within the population-based cohort were significantly more likely to have smaller tumors at diagnosis (78% intracanalicular versus 45%; p = 0.004) and consequently more likely to undergo management consisting of observation with serial imaging as opposed to treatment with either microsurgery or radiosurgery (71% versus 28%; p = 0.001). Conclusions: The reliance on pathology specimens and cancer-related treatment data for the national registration of new cancer and brain tumor diagnoses may introduce selection bias and underreporting of benign brain tumors that frequently involve observation as a primary treatment modality. This selection bias likely accounts for the discrepant incidence rates of vestibular schwannoma reported between the United States and other countries.

Background: Previous cross-sectional studies analyzing quality of life (QOL) outcomes in patients with sporadic vestibular schwannoma (VS) have shown surprisingly little difference among treatment modalities. To date, there is limited prospective QOL outcome data available comparing baseline to posttreatment scores. Study Design: Prospective longitudinal study using the disease-specific Penn Acoustic Neuroma Quality of Life (PANQOL) scale. Setting: Large academic skull base center. Patients: Patients diagnosed with unilateral VS who completed a baseline survey before treatment and at least one posttreatment survey. Main Outcome Measures: Change in PANQOL scores from baseline to most recent survey. Results: A total of 244 patients were studied, including 78 (32%) who elected observation, 118 (48%) microsurgery, and 48 (20%) stereotactic radiosurgery. Patients who underwent microsurgery were younger (p < 0.001) and had larger tumors (p < 0.001) than those who underwent observation or radiosurgery; there was no significant difference in duration of follow-up among management groups (mean 2.1 yrs; p = 0.28). When comparing the total PANQOL score at baseline to the most recent survey, the net change was only –1.1, –0.1, and 0.3 points on a 100-point scale for observation, microsurgery, and radiosurgery, respectively (p = 0.89). After multivariable adjustment for baseline features, there were no statistically significant changes when comparing baseline to most recent scores within each management group for facial function, general health, balance, hearing loss, energy, and pain domains or total score. However, the microsurgical group experienced a 10.8-point improvement (p = 0.002) in anxiety following treatment, compared with 1.5 (p = 0.73) and 5.3 (p = 0.31) for observation and radiosurgery, respectively. Conclusions: In this prospective longitudinal study investigating differences in QOL outcomes among VS treatment groups using the disease-specific PANQOL instrument, treatment did not modify QOL in most domains. Microsurgery may confer an advantage with regard to patient anxiety, presumably relating to the psychological benefit of “cure” from having the tumor removed.