Recent Advances in Understanding Audiovestibular Loss of a Vascular Cause

Abstract

Acute audiovestibular loss is characterized by abrupt onset of prolonged (lasting days) vertigo and hearing loss. Acute ischemic stroke in the distribution of the anterior inferior cerebellar artery (AICA) is known to be the leading cause of acute audiovestibular loss. So far, eight subgroups of AICA territory infarction have been identified according to the patterns of audiovestibular dysfunctions, among which the most common pattern is the combined loss of auditory and vestibular functions. Unlike inner ear dysfunction of a viral cause, which can commonly present as an isolated vestibular (i.e., vestibular neuritis) or cochlear loss (i.e., sudden deafness), labyrinthine dysfunction of a vascular cause rarely results in isolated loss of vestibular or auditory function. As audiovestibular loss may precede the central symptoms or signs of an ischemic stroke in the posterior circulation, early diagnosis and proper management of audiovestiubular loss may provide a window to prevent the progression of infarction to larger areas of the posterior circulation. A clinician should consider the possibility that acute audiovestibular loss may herald impending AICA territory infarction, especially when patients have basilar artery occlusive disease close to the origin of the AICA on brain MRA. This review aims to highlight the recent advances in understanding audiovestibular loss of a vascular cause and to address its clinical significance.

Keywords: Anterior inferior cerebellar artery; Audiovestibular loss; Hearing loss; Prodrome; Stroke; Vertigo.

Figure 1.

MRI and audiovestibular findings in a patient with recurrent vertigo and fluctuating hearing loss with tinnitus – prodromal signs of AICA territory infarction. A) Normal axial diffusion-weighted brain MRI 1 day after the onset of recurrent vertigo and fluctuating right-sided hearing loss with tinnitus. B) An initial pure tone audiogram performed reveals moderate degree of hearing loss with 24% speech discrimination in the right ear. Hearing levels in decibels (dB) (American National Standards Institute, 1989) are plotted against stimulus frequency on a logarithmic scale. C) Video-oculographic recordings of bithermal caloric tests performed showed right canal paresis (65%). Three days later, patient complained of exacerbation of vertigo and hearing loss on the right ear. On examination, there was bidirectional gaze-evoked nystagmus and dysmetria on the right limb. D) Follow-up axial diffusion-weighted MRI demonstrated hyperintense foci involving the right anterior cerebellum including the flocculus. E) Follow-up pure tone audiogram shows aggravated profound hearing loss on the right ear. AICA, anterior inferior cerebellar artery; Vmax, maximal velocity of slow phase of nystagmus.