Longitudinal Evaluation of Vestibular Symptoms in Patients with Vestibular Schwannoma After Robotic-Guided Stereotactic Radiosurgery Using the Dizziness Handicap Inventory (Dhi))

BACKGROUND: Vestibular symptoms can severely affect patients with vestibular schwannomas (VS). In patients with VS treated by stereotactic radiosurgery (SRS), studies addressing vestibular symptoms beyond clinical routine assessment (VSYM-clin) are scarce. To objectively evaluate vestibular symptoms, we here introduced the standardized questionnaire Dizziness Handicap Inventory (DHI). METHODS: For this retrospective single center study we included all patients who received Cyberknife® SRS for newly diagnosed unilateral VS between 2012 and 2022, and who had a minimum of three follow-up (FU) visits. Besides clinical assessment (VSYM-clin), the presence and severeness of vestibular symptoms before and after treatment was recorded by using the DHI. Overall DHI symptom scores (1-100) were classified into four categories (0=“none”, 1=“mild”, 2=“moderate” and 4=“severe”). The results were correlated with tumor-, patient-, and treatmentrelated characteristics. RESULTS: We identified 128 patients with a median age of 60 years (range: 20-82) and a median follow-up of 36 months (range: 11-106 months). Median tumor volume was 0.99 cm3 (range: 0.04-7.1 cm3). A median marginal dose of 13 Gy (range: 12-14 Gy) was administered. Local tumor control was 100%. The mean DHI total score at last follow-up (LFU, 25.5 ± 24.7; range 0-92) was significantly lower than before SRS (29.4 ± 25.3; range:0-92, p=0.026), reflected in an increased proportion of patients with DHI “none” category and a decreased proportion of patients with DHI “severe” category at LFU. Chi-square tests showed a significant correlation of the DHI categories (DHI 0-1 vs. DHI 2-3) with the absence or presence of VSYMclin both before SRS (p<0.001, CI 95%) and at LFU (p=0.038). CONCLUSIONS: The DHI has proven to be a feasible and reliable instrument for measuring vestibular symptoms after SRS. In this cohort, DHI scores improved significantly during FU. However, only a minority of VS patients suffers from severe DHI scores before and after SRS.