Cerebrovascular Complications during Vestibular Schwannoma Surgery

Background Cerebrovascular accidents (CVA) are rare complications of vestibular schwannoma (VS) surgery; correspondingly, they have been infrequently reported, and not previously studied as a primary endpoint. Our objective was to assess the overall incidences of radiographic or clinical findings suggestive of postoperative CVA in a large, single-surgeon cohort, as well as their correlation and treatment implications.

Methods A prospectively maintained clinical VS database of 591 patients was retrospectively reviewed. Three-month postoperative MRIs underwent blinded screening for abnormal findings suggestive of CVA, including T2 hyperintensity in the middle cerebellar peduncle (MCP), pons, or cerebellum, or new posterior fossa encephalomalacia. Clinical records were separately queried for documentation of history or exam findings consistent with postoperative CVA. Patients with positive radiographic or clinical findings underwent extensive secondary review.

Results Sixty-one patients had radiographic findings consistent with possible postoperative CVA (10%); of them, 8 had intraoperative documentation of vascular injury (1.4%), and 4 had postoperative exam changes indicative of CVA (0.7%). No patients had clinical CVA findings without corresponding radiographic abnormalities. Intraoperative vascular injuries precipitating clinical CVAs involved the venous system (n = 3, 5%), or anterior inferior cerebellar artery (AICA, n = 1, 2%); corresponding clinical deficits included hemiparesis (n = 1, 2%), trigeminal sensory loss (n = 2, 4%), and dysphagia (n = 2, 2%). Facial nerve function was unfavorable (House-Brackmann 3–6) in two patients (50%). Three required out-of-home placement at hospital disposition (75%). As compared with the remainder of the radiographic CVA cohort (n = 57), the clinical CVA subgroup (n = 4) was not significantly associated with tumor size (median: 3.6 vs. 3.4 cm, p = 0.6), presence of tumor cyst (7 vs. 0%, p = 0.45), or gross total resection (GTR; 44 vs. 75%, p = 0.22). Length-of-stay was not significantly different (median 5 vs. 6 days, p = 0.91), but out-of-home disposition and post-hospitalization rehabilitation were significantly associated with CVA (19 vs. 75%, p = 0.02; 14 vs. 100%, p = 0.0002). Overall rate of unfavorable facial nerve outcomes in the radiographic CVA cohort was 19.7% (n = 12); although not statistically significant, this was appreciably lower rate than two of four patients demonstrating House-Brackmann 3 to 6 facial nerve function in the clinical CVA subgroup (p = 0.16). Clinically silent intraoperative vascular injuries involved AICA (n = 3, 5%) or posterior inferior cerebellar artery (PICA, n = 1, 2%). Other radiographic abnormalities included T2 hyperintensity of the MCP (n = 48, 79%), cerebellum (n = 3, 5%), multiple discrete locations (n = 10, 16%), and/or new encephalomalacia (n = 33, 54%).

Conclusion Although radiographic findings suggestive of intraoperative CVA were commonplace in this cohort, intraoperative vascular injury and postoperative clinical CVA were exceedingly rare occurrences in VS surgery. Unsurprisingly, clinical CVA was associated with poor outcomes. The trend toward association between unfavorable facial nerve outcome and clinical CVA is likely a marker for more difficult operations, predisposing patients to higher risk of these parallel complications.