Detection of utricular dysfunction using ocular vestibular evoked myogenic potential in patients with benign...

The ocular vestibular evoked myogenic potential (oVEMP) is thought to originate from the contralateral utricular organ. However, the clinical use of oVEMP has not yet been established. This study aimed to clarify whether oVEMP could be used to detect utricular dysfunction in patients with benign paroxysmal positional vertigo (BPPV).

Sixteen patients with BPPV underwent oVEMP measurements. Recordings were made on 2 separate occasions: when typical nystagmus was confirmed (pretreatment oVEMP) and 1 week after performing Epley's maneuver (posttreatment oVEMP). Results were evaluated using the asymmetry ratio (AR) of n1-p1 wave peak-to-peak amplitude and defined as reduced oVEMP when AR was >31.6%, or augmented oVEMP when AR was <-31.6%.

Bilateral responses were recorded in 13 patients on the pretreatment oVEMP. Abnormal results were found in 11 patients (84.5%). These included 5 patients with reduced response and 6 with augmented response. On the posttreatment oVEMP, abnormal results were found in 5 patients (38.5%). All indicated reduced oVEMP. Abnormal results on the pretreatment oVEMP were not related to any persistent positional vertigo (p>0.05, Fisher's exact test). Three out of 4 patients (75.0%) with continuing unsteadiness had abnormal results (reduced response) on the posttreatment oVEMP.

The oVEMP measurements indicated abnormal function of the utricle in patients with BPPV. Reduced oVEMP is thought to originate from the partial degeneration of utricular hair cells. Conversely, augmented oVEMP in the affected ear is thought to originate from a hypermobility of the stereocilia due to the detachment of otoconia within the utricle. The above-mentioned utricular dysfunction should be independent of the existence of otoconia in the semicircular canal; thus, the results of oVEMP were not related to the recovery of symptoms.

oVEMP can be reliably used to detect utricular lesions in patients with BPPV.