Voluntary Upper-Extremity Movements in Patients With Unilateral Peripheral Vestibular Hypofunction

Abstract

People with peripheral vestibular pathology demonstrate motor impairments when responding and adapting to postural platform perturbations and during performance of sit-to-stand and locomotor tasks. This study investigated the influence of unilateral peripheral vestibular hypofunction on voluntary arm movement. Subjects without known neurological impairments and subjects with vestibular impairments performed 3 voluntary arm movements: an overhead reach to a target, a sideward reach to a target, and a forward flexion movement through 90 degrees. Subjects performed these tasks under precued and choice reaction time conditions. During all tasks, body segment motion was measured. Head velocity measurements were calculated for the side task only. Subjects with vestibular loss restricted upper body segment motion within the frontal and transverse planes for the 90-degree and overhead tasks. Average angular head velocity was lower for the group with vestibular hypofunction. Task uncertainty (the introduction of a choice reaction time paradigm) differentially influenced the groups regarding head velocity at target acquisition. Individuals with vestibular loss altered their performance of voluntary arm movements. Such alterations may have served to minimize the functional consequences of gaze instability.