[Evoked potentials in multiple sclerosis: progress or stagnation?]

Evoked potentials (EPs): visual (VEP), short latency somatosensory (SSEP), brainstem auditory (BAEP) and motor evoked potentials (MEP) can provide objective evidence of central nervous system (CNS) abnormalities that complement the clinical and radiological findings in establishing the diagnosis of multiple sclerosis (MS).

The EPs studies may also improve the sensitivity of MS diagnosis.

Abnormal EPs can provide evidence for pathology to satisfy the diagnostic criteria of lesions disseminated in space in the absence of clinical findings and for a relapse in patient with new symptoms but no changes on clinical examination. Since magnetic resonance imaging (MRI) plays a critical role in the current diagnostic criteria of MS, it is important to consider the relationship between EPs and MRI. Evoked potentials provide neurophysiological information about CNS functional abnormalities, while MRI provide anatomical localisation of CNS lesions. VEPs are even more sensitive than MRI in detecting acute and old pre-chiasmatic optic nerve lesions. The revised diagnostic criteria for MS include the provision for an abnormal VEP to serve as a diagnostic factor. Rarely, patients with spinal cord pathology may have an abnormal SEP or MEP without an observed lesions on MRI. Combining multimodality evoked potentials and MRI results in the greatest diagnostic yield.

More widespread use of multimodality EPs in combination with MRI might lead to better outcome measurement in clinical trials as well as in open therapeutic approach. Thought EPs have some limitations, they remain an important factor in the diagnosis and clinical management of MS patients.