(0931) Examining Clinical and Radiographic Evidence of Cerebellar Dysfunction Following Vestibular Schwannoma Surgery

Introduction: The retrosigmoid (RS) approach for microsurgical resection of vestibular schwannoma offers the potential advantages of improved posterior fossa access and the possibility of hearing preservation in select cases. However, many have concern regarding the adverse effects of cerebellar retraction with this approach.

Methods: Single institution retrospective chart review (2011-2023) examining postop cerebellar dysfunction in patients undergoing primary acoustic neuroma resection via translabyrinthine (TL), retrosigmoid (RS) and middle cranial fossa (MCF) approaches. Demographics, clinical presentation, postop imaging, exam and audiology outcomes were collected. Chi-square, ANOVA, and non-parametric analysis were used to compare the surgical groups and examine preop factors associated with postop clinical cerebellar injury on exam (dysmetria, dysdiadochokinesia with severe ataxia) and cerebellar changes on MRI (increased FLAIR signal on T2 images, quantified as % of cerebellar area). Case match comparison was used to compare TL and RS results.

Results: Patients undergoing a RS approach were more likely to have large tumors (32/34 cases, p < 0.05) and preop brainstem compression (40/41 cases, p < 0.05). Surgical time and hospital stay was comparable between RS (n-77) and TL (n-21) approaches but shorter for MCF (n-13). Large tumor size, preop brainstem compression and surgical time were independently associated with likelihood of postop cerebellar MRI changes (p < 0.05). RS patients more commonly had minor MRI postop FLAIR signal cerebellar changes (30/77), measuring 2.5% +/- 0.6% for those 30 patients, compared to TL (1/21, 0.4%). MRI changes were not independently correlated with postop clinical cerebellar dysfunction. Case match analysis (14 RS/14 TL) showed RS patients were more likely to have radiographic cerebellar FLAIR changes postop compared to the TL cohort (p < 0.05), no clinical exam correlation was seen.

Conclusions: Patients undergoing RS approach for VS were more likely to have minor radiographic cerebellar changes. Differences in cerebellar postop function was not seen.