Clinical Significance of Middle Cerebellar Peduncle Ischemia After Translabyrinthine Vestibular Schwannoma Resection

Abstract

Objective: To assess clinical symptoms, signs, and radiographic evolution of middle cerebellar peduncle (MCP) diffusion restriction (DR) abnormalities following vestibular schwannoma (VS) resection. Study Design: Retrospective chart and imaging review. Setting: Tertiary-referral neurotology and neurosurgery practice. Patients: All consecutive patients who underwent translabyrinthine VS resection over a 2-year period (August 2017–May 2019). Intervention: Translabyrinthine craniotomy for VS resection. Main Outcome Measures: Magnetic resonance imaging (MRI) obtained on postoperative day 1 were reviewed for DR within the pons and cerebellum, with 3\u200amonths follow-up MRI to assess for evolution of these vascular changes. Results: Of the 31 patients who met inclusion criteria, MRI demonstrated MCP DR consistent with acute ischemia in 29% (9/31). Of those, two showed corresponding T2 signal abnormalities on follow up MRI consistent with cerebrovascular accident (CVA) within the MCP. Both had severe gait ataxia and dysmetria requiring acute rehabilitation admission and significantly larger tumors (p\u200a=\u200a0.02). The remaining seven were asymptomatic, and DR abnormality resolved without lasting radiographic changes. Brainstem compression was present in 100% of patients with postoperative MCP DR (mean MCP ipsilateral:contralateral ratio 0.59\u200a±\u200a0.19), and 68.1% of those without (mean MCP ratio 0.71\u200a±\u200a0.25), a difference that was not statistically significant (p\u200a=\u200a0.14). In the two patients with CVA, MCP asymmetry persisted, whereas the asymmetry resolved in all others. Conclusions: Asymptomatic acute MCP ischemia discovered incidentally does not require intervention. However, when the ischemic area is large and patients are symptomatic, especially if an acute rehabilitation admission is required, surgeons should suspect true CVA.