Semicircular canal, saccular and utricular function in patients with bilateral vestibulopathy: analysis based on etiology

Abstract

The diagnosis of bilateral vestibulopathy (BV) is typically established based on bilateral semicircular canal dysfunction. The degree to which both otolith organs—the saccule and utricle—are also impaired in BV is not wellestablished, particularly with respect to the etiology and severity of BV. The aim of this study was to evaluate semicircular canal, saccular and utricular function in patients with BV due to aminoglycoside ototoxicity and bilateral Menière’s disease, and with different severities of BV. Caloric and head impulse testing were used as measures of canal function. Cervical vestibular-evoked myogenic potentials (cVEMP) and ocular VEMPs (oVEMP) were used as measures of saccular and utricular function, respectively. We enrolled 34 patients with BV and 55 controls in a prospective case–control study. Patients with BV were less likely to have saccular (61 %) or utricular (64 %) dysfunction relative to canal dysfunction (100 %). Utricular function differed significantly between patients by etiologic group: the poorest function was found in patients with BV due to aminoglycoside toxicity, and the best function in Menière’s disease patients. Canal and saccular function did not vary according to etiology. Further, utricular but not saccular function was significantly correlated with canal function. Saccular and utricular function had the strongest association with Dizziness Handicap Inventory scores relative to canal function. These data suggest that when a patient with BV is identified in a clinical context, oVEMP testing is the most sensitive test in distinguishing between aminoglycoside toxicity and bilateral Menière’s disease. Both cVEMP and oVEMP testing may be considered to evaluate the functional impact on the patient.

Prevalence and Impact of Bilateral Vestibular Hypofunction

“…Patients who acquire BVH acutely as adults, however, may be dramatically affected by relentless disequilibrium, chronic oscillopsia and cognitive dysfunction due to the need for constant attention to normally automatic functions like walking 1 . Dizziness Handicap Inventory scores have recently been shown to vary in subjects with bilateral vestibulopathy depending on residual otolith function 19 . While BVH subjects as a group report profound impairments in quality of life, functional impairment may vary depending on age of onset and degree of vestibular loss.…”

Bilateral Vestibular Hypofunction: Challenges in Establishing the Diagnosis in Adults

“…Differences in response to the caloric test versus the rotation tests versus HIT are especially pointing to this difference in frequency content. It has been shown that a bilateral vestibular loss can be measured with the caloric test, while the responses as measured with HIT are relatively preserved [95,96]. In other words, it is necessary to understand that the presence of a normal vestibulo-ocular reflex as measured with HIT does not rule out a vestibular deficiency.…”

“…However, while it is necessary to take the total response into account, there is still no consensus on the range of responses required for the diagnosis of BVH [7,10,118,127]. A criterion often suggested for diagnosing BVH is to have a sum of 4 irrigations that is less than 20°/s [7,12,18,95]. While this is highly specific, it could still lead to false-positive results (partly due to the anatomical variations mentioned above) and also, very importantly, to false-negative results.…”

Downbeat nystagmus: evidence for enhancement of utriculo-ocular pathways by ocular vestibular evoked myogenic potentials?

“…The VEMP examination was performed as published elsewhere [15]. Briefly, oVEMP were recorded with recording electrode placed over the inferior oblique muscle bilaterally, approximately 3 mm below the eye and centered beneath the pupil, a reference electrode on the chin; and a ground electrode placed under the chin.…”