Magnetic resonance imaging results in patients with central electronystagmography findings

Abstract

The objective of this study was to determine the findings on magnetic resonance imaging (MRI) in patients identified as having central vestibular abnormalities on electronystagmography (ENG) testing, to discuss the issue of 'gold standard' in the investigation of central oculo-vestibular system diseases and to present a model for understanding this area. A retrospective review of the case notes of patients (n = 23) found to have central ENG findings at vestibular assessment and for whom MRI scanning data was available was undertaken. Each patient underwent a full ENG evaluation, including gaze, ocular-motor and caloric testing, and MRI. Only seven of the patients with central ENG findings had abnormal MRI scans. Thus, the incidence of the identification of structural abnormality on MRI in patients with central ENG findings is low. These investigations are complementary in the investigation of balance disorder patients.

Do central vestibular findings predict abnormal findings on magnetic resonance imaging?

“…An older study by Stoddart et al . 20 reported that the incidence of structural abnormality identification using MRI in patients with central ENG findings is low. Currently, videonystagmography, video head impulse tests and vestibular evoked myogenic potentials are used for vestibular testing and advances in MRI technology have improved its sensitivity in identifying abnormal white matter lesions compared to CT. 21…”

Relative diagnostic importance of electronystagmography and magnetic resonance imaging in vestibular disorders

“…Of the clinical signs of a central lesion, vertical nystagmus was the only one diagnosed in this population. In terms of ENG findings, the abnormalities indicative of central lesions which were identified in our series were square waves, abnormal saccades in terms of accuracy and a low fixation index in caloric responses 4 . A directional preponderance may be present in both central and peripheral lesions 7 .…”

“…Firstly, MRI was performed in all patients with a diagnostic dilemma, not just those with previous abnormal ENG findings suggestive of a central lesion. This methodological difference may be crucial in enabling identification of patients with central lesions who may otherwise escape diagnosis because they have undergone only ENG 4 , 5 . In addition, through this procedure, one may estimate the number of patients with functional abnormalities of the vestibulo-ocular system which have escaped MRI diagnosis, either because they are peripheral or because they are not presented as detectable, concise, structural lesions.…”

“…In the other six patients, the functional abnormalities detected by the ENG were not confirmed by congruent structural lesions in the MRI. Stoddart et al reported that, of 23 patients undergoing MRI after having demonstrated abnormal ENG recordings of central origin, only seven (30 per cent) had pathological MRI findings 4 . Similarly, Kinney et al calculated the diagnostic sensitivity of MRI to be only 30 per cent, using ENG as the gold standard 6 .…”

“…However, a review of the current, relevant literature reveals that studies which compare the diagnostic value of MRI and ENG in such patients appear to be lacking. There are several case studies which have demonstrated correlations in certain conditions, such as multiple sclerosis, Arnold–Chiari malformation and vestibular migraine, 1 – 3 and a few other studies which have examined MRI findings in patients who had already undergone ENG and were found to present abnormalities indicative of central nervous system (CNS) dysfunction 4 – 6…”