Post-operative vestibular function outcomes evaluated by video Head Impulse Test in patients with non-vestibular schwannoma cerebellopontine angle tumors

Objectives: To evaluate post-operative semicircular canal function in patients with non-vestibular schwannoma (VS) cerebellopontine angle (CPA) tumors by video Head Impulse Test (vHIT).

Methods: Fourteen patients with non-VS CPA tumors who underwent surgery. The gain in vestibulo-ocular reflex (VOR) was examined pre- and post-operatively for the semicircular canals in patients with non-VS CPA tumors.

Results: Ten of 14 patients showed semicircular canal dysfunction in one or more of the semicircular canals pre-operatively and VOR gain was significantly correlated with hearing function. Two patients showed improvement in one or more semicircular canals at 1 month after surgery compared to the pre-operative results. Significant improvements in VOR gain were observed when comparing VOR gain at 1 month and 6 months after surgery.

Conclusions: Detailed evaluation of semicircular canal function was achieved by using vHIT in patients with non-VS CPA tumors. The good prognosis for vestibular function as evaluated by vHIT post-operatively was confirmed in patients with non-VS CPA tumors when compared to those in patients with VS. As improvement may occur post-operatively, surgical approaches that preserve the vestibular nerves and semicircular canals should be chosen for patients with non-VS CPA tumors, regardless of preoperative vestibular function. Even if vestibular function deteriorates immediately after surgery, it may improve over time if the nerve is preserved.