Falling Mechanics Are Altered After Vestibular Schwannoma Surgery-A Case Report.

Abstract

Background: We describe the falling mechanics in a 75-year-old patient diagnosed with a left vestibular schwannoma. The patient completed an experimentally designed fall paradigm before and after vestibular schwannoma treatment.Purpose: This case describes the change in neck muscle activation, vestibular function, and falling mechanics before and after left gamma stereotactic surgery.Research Design: This is a case study.Data Collection and Analysis: This patient completed two falls in three directions (backward, left, and right) before and after treatment. Motion capture and video review assessed kinematic data of falls and head impact. Neck muscle activation was collected from bilateral upper trapezius (UT) and sternocleidomastoid (SCM) muscles. Vestibular function was assessed by vestibular evoked myogenic potential (VEMP) and the video head impulse test.Results: The participant had a minor head impact before and after treatment with falls to the right. Head acceleration during falls was higher posttreatment in backward and left falls. Reduction in bilateral SCM and right UT activation but increased activation of the left UT was noted after treatment, regardless of fall direction. The left cervical VEMP that was present before treatment was absent after treatment, and the video head impulse test gain was greater than 0.8 in all directions except for the left posterior canal (0.63 before treatment), which decreased to 0.47 after treatment.Conclusions: The number or severity of head impacts did not increase despite reduced vestibular function, indicating that the participant used a different neuromuscular strategy to avoid head impact.