HSC Section 8_April 2017

Fig. 1. Serial axial T1-weighted MRI with gadolinium (A) demonstrating a right-sided vestibular schwannoma with 0.5 cm of cisternal exten- sion that was treated with primary stereotactic radiosurgery. (B) Following radiation, the tumor demonstrated progressive growth to a size of 1.2 cm over the course of 3.4 years. (C) The patient subsequently underwent translabyrinthine craniotomy with gross total resection and has no evidence of residual progressive disease with over 2 years of follow-up.

integrity. 6 It has even been argued that primary micro- surgery with gross total resection (GTR) is the preferred treatment altogether for VS to avoid the challenges and potential morbidity of surgery following radiation. 8 In this study, we report our experience treating a series of patients with VSs that failed primary SRS and under- went microsurgery for salvage.

Primary outcome measures included facial nerve function and tumor control following salvage surgery. Descriptive statis- tics were used to describe demographic and clinical data. Wil- coxon rank-sum and Fisher’s exact tests were used to compare continuous and categorical variables as appropriate. Logistic regression modeling was performed to identify independent var- iables associated with good (HB grade I–II) postoperative facial nerve outcome after adjusting for age, tumor size, extent of resection, and duration of follow-up. Research approval was obtained from the institutional review board (IRB 13-009442) and the regional ethical committee (NSD 13199) at each partici- pating institution, respectively, prior to study commencement. Data were analyzed using JMP 10 Statistical Discovery Soft- ware (S.A.S. Institute Inc., Cary, NC). P values < 0.05 were considered statistically significant. Thirty-seven patients underwent salvage surgery for radiation treatment failure between 2003 and 2015 (Fig 1). Indications for initial tumor radiation included docu- mented tumor growth (35, 95%) or patient preference (2, 5%). Fifty-one percent of patients were female, and the median age at time of primary SRS was 57 years (range 30–80 years). At the time of primary presentation, all patients had normal facial nerve function, and pretreat- ment hearing class was documented in 35 cases: 15 (43%) were class A; two (6%) were class B; two (6%) were class C; and 16 (46%) were class D. Other primary pre- senting symptoms included imbalance (6, 16%) and tri- geminal neuropathy (3, 8%). The median tumor size was 1.5 cm (range 0.5–2.9 cm) and 24 (65%) were right-sided. Four (11%) VSs were confined to the internal auditory canal, two (5%) were cystic, and none presented with brainstem edema. The original tumor size was unknown or missing from the medical record for three patients who initially received radiation treatment elsewhere. Table I summarizes treatment characteristics of the 37 subjects who received primary radiation therapy. Thirty-three patients (89%) from this group were treated at the authors’ institutions, whereas four were referred from outside centers after diagnosis of tumor growth fol- lowing prior radiation. Following radiation, three (8%) RESULTS Primary Radiation Therapy

MATERIALS AND METHODS Study Design

Prospectively maintained VS clinical databases at two sep- arate institutions were queried, and all patients who underwent salvage surgery between 2003 and 2015 for recurrent sporadic VS after primary radiation failure were identified. Patients with neurofibromatosis type 2 (NF2) were excluded. Matched controls were identified from the same clinical databases, including sub- jects who underwent primary microsurgery for treatment of spo- radic VS. Match criteria included patient age (within 5 years), tumor size (within 5 mm), and treatment center. Demographic, baseline clinical, and treatment outcome data were collected. Tumor size and hearing class were reported according to the American Academy of Otolaryngology–Head and Neck Surgery guidelines for VS outcomes. 10 Facial nerve function was scored according to the House-Brackmann (HB) grading scale. 11 Cystic VS was defined as a tumor with a predominant cystic appear- ance. Growth was defined as greater than 2-mm increase in lin- ear dimension on serial imaging. Great care was taken to avoid misinterpreting postradiation tumor swelling, typically seen on the initial 6-month follow-up magnetic resonance imaging (MRI) scan, as tumor growth. 12 Serial post-SRS imaging was available in 36 of 38 (95%) cases, whereas two patients had only one post- SRS scan prior to salvage surgery. The authors define GTR when all microscopic disease has been removed; near total resection (NTR) is specified when less a 5 3 5 3 2-mm pad of adherent tumor is intentionally left on the facial nerve, brainstem, or vas- culature to preserve neurological integrity; and subtotal removal is specified when anything less than near total resection is per- formed. 13 Following SRS, serial MRI scans are generally obtained every 6 months for the first year, then annually for the next 2 years and biennially thereafter. Following microsurgical resection of VS, postoperative clinical and radiographic (MRI) follow-up was performed at 3 months and at a minimum of every 2 years thereafter. More frequent follow-up was performed when clini- cally indicated if less than GTR was performed.

Wise et al.: Surgical Salvage for Recurrent VS

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