Selective otolithic dysfunction in patients presenting with acute spontaneous vertigo: consideration based on MRI

Abstract

Objective: Acute unilateral peripheral vestibulopathy or vestibular neuritis (AUPV/VN) manifests as acute onset vertigo, often accompanied by nausea, vomiting, and moderate gait instability. It is suspected when vestibular hypofunction is documented on video-head impulse (video-HITs) and caloric tests in the presence of contralesionally beating horizontal-torsional nystagmus. Herein, we report patients presenting with acute vestibular syndrome (AVS) showing selective otolithic dysfunction in the presence of normal caloric and video-HITs and abnormal enhancement of the peripheral vestibular structures on MRI.

Methods: We retrospectively reviewed the medical records of patients presenting with AVS between September 2019 and April 2024 at a tertiary referral hospital in South Korea. All patients underwent extensive neurotologic evaluation, including cervical and ocular vestibular-evoked myogenic potentials (cVEMP and oVEMP, respectively), subjective visual vertical, video-oculography, video-HITs, caloric tests, and audiometry. Patients also underwent MRI according to a standard protocol for the inner ear and internal acoustic canal with an additional 3D-fluid attenuated inversion recovery sequence acquired 4 h after intravenous gadolinium injection.

Results: We identified four patients with selective otolith dysfunction. Video-HITs and caloric test results were normal in all patients, except one with a canal paresis on the opposite side of otolithic dysfunction. Patients usually showed abnormal oVEMP (n = 3) and cVEMP (n = 2) or subjective visual vertical (n = 3). Gadolinium enhancements were found in the vestibule (n = 3), inferior (n = 2) or superior (n = 1) vestibular nerves on dedicated inner ear MRI.

Discussion: Selective otolithic dysfunction can present with AVS, which can be easily overlooked. A thorough neurotologic evaluation and MRI dedicated to the inner ear can help detect selective otolithic dysfunction, expanding the clinical spectrum of AVS.

Keywords: dizziness; magnetic resonance imaging; otolith; vertigo; vestibular neuritis.

Figure 1

4-h delayed 3D-FLAIR images of the patients. Quantitative evaluation of a degree of the perilymphatic enhancement. The signal intensity ratios of the vestibular nerves and inner ear structure to that of the signal intensity of the medulla were calculated to avoid bias from patient-related artifacts.

Figure 2

Neurotologic findings in patient 4. (A) Video-oculography shows spontaneous nystagmus beating rightward, upward with a clockwise component. (B) Video head-impulse tests are normal. (C) Bithermal caloric tests reveal canal paresis of 33% in the right ear. (D) cVEMP and oVEMP show relatively decreased response during left ear stimulation, with 25.7 and 33.3% interaural differences, respectively. AC, anterior canal; cVEMP, cervical vestibular-evoked myogenic potential; H, horizontal position of the right eye; HC, horizontal canal; oVEMP, ocular VEMP; PC, posterior canal; T, torsional position of the right eye; V, vertical position of the right eye.

Figure 3

Initial and follow-up neurotologic evaluation of patient 2. (A) Initially, video-oculography showed spontaneous nystagmus beating right and clockwise (the torsional graph is omitted since artifacts). (B) Video head-impulse tests are normal. (C) Initially, oVEMP and cVEMP responses are decreased during left ear stimulation. (D) These decreased cVEMP and oVEMP responses become normal 3 months later. AC, anterior canal; cVEMP, cervical vestibular-evoked myogenic potential; H, horizontal position of the left eye; HC, horizontal canal; oVEMP, ocular VEMP; PC, posterior canal; V, vertical position of the left eye.