Disease 05.7

Multiple Sclerosis

VEMP earns a role in MS as a functional test of brainstem conduction — sometimes abnormal when MRI is not.

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Foundation

What does MS have to do with VEMPs?

Multiple sclerosis causes patchy demyelination of the central nervous system. When plaques affect the brainstem pathways through which the VEMP reflex arc runs (the medial longitudinal fasciculus, vestibular nuclei, vestibulospinal tract), the response is altered — characteristically by latency prolongation rather than amplitude reduction.

AudiogramThe pure-tone signature
1252505001k2k4k8kFrequency (Hz)020406080100dB HLRL
Hearing is typically normal in MS — demyelination of the auditory pathway is unusual and would more commonly affect higher central auditory processing rather than producing a peripheral hearing loss. A normal audiogram in someone with brainstem signs is itself diagnostic of a central lesion until proven otherwise.
01020304050Time (ms)NormalMS (central demyelination)
Latency prolongation with preserved amplitude — the central pattern. Contrasts with the amplitude reduction seen with peripheral pathology.
Trainee

VEMP signature

  • Prolonged P1 latency — the most characteristic finding.
  • Preserved or only mildly reduced amplitudes in the early phase.
  • Abnormal in around 50–70% of MS patients with vestibular symptoms.[21,22]
  • Can be abnormal even with a normal MRI — making VEMP a complementary functional test.
Clinician

Evidence base

Eleftheriadou and colleagues showed that the diagnostic yield of VEMP in MS is maximised by combining the p13-n23 (cVEMP) and n34-p44 (a later cVEMP component) for analysis: the p13-n23 was abnormal in 50% of patients, the n34-p44 in 43%, and the combined yield was approximately 71%.[21] A more recent systematic review of VEMP in MS reaffirms its utility as a functional measure of brainstem integrity that may complement MRI in selected cases.[22]

Reading the report

A patient with optic neuritis but a normal MRI brainstem who then develops vertigo should have VEMP testing considered. A prolonged latency would support central demyelination affecting the brainstem and inform the dissemination-in-space criteria for MS diagnosis.