Visual Evoked Potential Study in Multiple Sclerosis Disease

Purpose: To demonstrate visual evoked potential (VEP) changes in multiple sclerosis (MS) disease Methods: A case series study of VEP changes in forty-nine patients with definite, probable and possible diagnoses of MS referred to electrophysiology ward from January 2002 to December 2005. Pattern VEP was done for those with good visual acuity (VA), and flash VEP was done for those who did not have central fixation or good VA. Characteristics of P-100 wave in pattern VEP and P-2 wave in flash VEP were evaluated. Results: The implicit time of P-100 and P-2 waves in pattern and flash VEP, demonstrated severe abnormalities in 84.5% of definite MS. In probable MS, implicit time increased in 81.8% cases. In possible MS cases, increased implicit time was seen in more than 50% of patients. Decrease in amplitude alone, was seen in a few cases. Combined changes of implicit time and amplitude were prominent. Conclusion: VEP is an invaluable electrophysiological test in MS for both diagnosis and follow-up of the patients. Concurrent with magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) analysis, VEP can help neurologists and ophthalmologists for better evaluation of MS patients.