The prognostic value of evoked potential abnormalities

Early alterations of evoked potentials (EPs) may help identify patients at high risk of long-term clinical deterioration and assist in decisions regarding immunomodulatory therapy, according investigators of a recent German study.The investigators studied whether evoked potential alterations in the first two years after MS disease onset correlated with clinical disability at later stages of the disease. They retrospectively analysed data from 94 patients, who were divided into two groups, according to when they were first examined: group one patients (n = 44) were first examined within two years after disease onset, and group two patients (n = 50) were first examined at later time points.The authors report, "Our study indicates that standard EPs recorded within two years after disease onset of MS (group 1) correlate with EDSS scores after five and ten years, while at later disease stages (group 2) no such projections are possible."In group one, sum scores for magnetic motor evoked potentials (MEP) and for somatosensory evoked potentials (SEP) at first examination correlated significantly with clinical disability (EDSS) after five years, and the combined SEP + MEP findings at first presentation best predicted five-year clinical disability. However, visual evoked potential (VEP) sum scores did not correlate with EDSS at any time point. In group 2, only the combined VEP + MEP + SEP sum score significantly correlated with EDSS at first presentation and after five years.There was no significant association between EP alterations and EDSS at first presentation. The authors note, "Thus, EP at this early stage do not reflect the existing degree of clinical disability as mirrored by EDSS... The ability of EP to disclose clinically silent lesions at early disease stages that also do not show on MRI is a strong argument for employing EP techniques in addition to MRI early in MS." They suggest that combined testing of EP modalities may help predict the severity of future clinical disability in MS patients and therefore may assist in early decisions regarding the introduction of immunomodulatory treatment.Reference...