Quantitative vestibular function tests in posterior circulation stroke patients: A review

While specific bedside examinations are known to be sensitive in identifying stroke among acute vestibular syndrome patients, complementary quantitative vestibular function testing can be helpful to quantify vestibular loss due to stroke. In contrast to peripheral vestibular dysfunction, diagnosis of central vestibular dysfunction can be challenging for unskilful clinicians. This article presents a comprehensive overview of quantitative vestibular function test findings such as the video head impulse test (vHIT), cervical vestibular evoked myogenic potentials (cVEMPs), ocular vestibular evoked myogenic potentials (oVEMPs), videonystagmography (VNG) and caloric test among stroke patients. Vestibulo-ocular reflex (VOR) gain is usually found normal among posterior inferior cerebellar artery (PICA) stroke patients but varies among anterior inferior cerebellar artery (AICA) stroke patients. Abnormal contralesional posterior semicircular canal VOR gain can be observed due to lesions in the medial longitudinal fasciculus (MLF). AICA and PICA stroke can impair cVEMPs, oVEMPs, and VNG (i.e., smooth pursuit and saccade functions). Strokes, particularly those involving the vestibular nucleus, including both upper, lower brainstem and cerebellum, can result in various abnormalities of smooth pursuit, saccade or calorics testing. The combined evaluations of VNG, vHIT, and VEMPs can be accurately used to complement and quantify bedside vestibular evaluation in diagnosing central vestibular dysfunction. In addition, as most studies were conducted amongst acute vestibular syndrome (AVS) patients, future studies that investigate the prevalence of vestibular dysfunction in recovering stroke patients are required.