Vestibular Evoked Myogenic Potential (VEMP) Triggered by Galvanic Vestibular Stimulation (GVS): A Promising Tool to Assess Spinal Cord Function in Schistosomal Myeloradiculopathy

Abstract

BackgroundSchistosomal myeloradiculopathy (SMR), the most severe and disabling ectopic form of Schistosoma mansoni infection, is caused by embolized ova eliciting local inflammation in the spinal cord and nerve roots. The treatment involves the use of praziquantel and long-term corticotherapy. The assessment of therapeutic response relies on neurological examination. Supplementary electrophysiological exams may improve prediction and monitoring of functional outcome. Vestibular evoked myogenic potential (VEMP) triggered by galvanic vestibular stimulation (GVS) is a simple, safe, low-cost and noninvasive electrophysiological technique that has been used to test the vestibulospinal tract in motor myelopathies. This paper reports the results of VEMP with GVS in patients with SMR.MethodsA cross-sectional comparative study enrolled 22 patients with definite SMR and 22 healthy controls that were submitted to clinical, neurological examination and GVS. Galvanic stimulus was applied in the mastoid bones in a transcranial configuration for testing VEMP, which was recorded by electromyography (EMG) in the gastrocnemii muscles. The VEMP variables of interest were blindly measured by two independent examiners. They were the short-latency (SL) and the medium-latency (ML) components of the biphasic EMG wave.ResultsVEMP showed the components SL (p = 0.001) and ML (p<0.001) delayed in SMR compared to controls. The delay of SL (p = 0.010) and of ML (p = 0.020) was associated with gait dysfunction.ConclusionVEMP triggered by GVS identified alterations in patients with SMR and provided additional functional information that justifies its use as a supplementary test in motor myelopathies.

Aplicações dos potenciais evocados miogênicos vestibulares: revisão sistemática de literatura

“…Silva et al (29) 2017 (20,21,29) . Sample size of the studies ranged from eight to 83 individuals with peripheral and central vestibular disorders.…”

“…Regarding the design, eight (29%) studies were descriptive (5)(6)(16)(17)(18)28,(30)(31) ,19 (68%) were comparative cross-secti onal (7)(8)(9)(10)(12)(13)(14)(15)(19)(20)(21)29,(32)(33)(34)(35)(36)(37)(38) , and one (3%) was longitudinal cohort (39) .…”

“…With respect to the diseases, the most commonly investigated clinical applications in patients with vestibular disorders referred to Meniere's disease (5)(6)29) , superior semicircular canal dehiscence syndrome (8)(9)(10)32) , vestibular schwannoma (12)(13) , and central ischemic lesions (15)(16)(17)(18)(19)(20)(21)(36)(37) .…”

“…Concerning the type of applied stimulation, the number (%) of studies using the sound or the electric stimulation were: 19 (68%), auditory -rarefaction tone burst (6)(7)9,12,(14)(15)(16)(17)(18)21,(28)(29)(30)(31)33,(35)(36)(38)(39) ; three (11%), auditory -rarefaction tone burst and click (8,13,32) ; two (7%), auditory -click (10,37) ; two (7%), galvanic (20,34) ; one (3.5%), auditory -click and galvanic (5) ; one (3.5%), auditory -rarefaction tone burst and galvanic (19) . The electric current intensity of galvanic stimulation ranged from 1 to 5 mA (5,19,20,34) .…”

“…The VEMP has been utilized to study a variety of vestibular diseases. Among peripheral diseases, Meniere's disease (5,6) , vestibular neuritis (7) , superior semicircular canal dehiscence (8)(9)(10) , large vestibular aqueduct syndrome (11) , and vestibular schwannoma (12,13) are highlighted, whereas among central vestibular diseases, vestibular migraine (14) , Parkinson's disease (15) , central ischemic lesions (16)(17)(18) , and motor myelopathies (19)(20)(21)(22)(23)(24)(25) stand out.…”