BRAIN-STEM TRIGEMINAL AND AUDITORY-EVOKED POTENTIALS IN MULTIPLE-SCLEROSIS - PHYSIOLOGICAL INSIGHTS

Thirty-six patients with multiple sclerosis were evaluated by means of brain-stem trigeminal and auditory evoked potentials. The brain-stem auditory evoked potentials (BAEPs) were abnormal in 26 patients (72.2% ). Brain-stem trigeminal evoked potentials (BTEPs) yielded similar res ults, showing distorted waveforms and/or prolonged latencies in 25 pat ients (69.4%). As expected, the MRI proved to be the most efficient si ngle test, revealing plaques in 86.4% of the patients evaluated. Howev er, the diagnostic accuracy of MRI was lower than that provided by the combination of the BTEP and the BAEP (88.9%). Moreover, in patients h aving signs of brain-stem involvement, the BTEP, alone and in combinat ion with the BAEP, proved to be more sensitive than the MRI in reveali ng brain-stem lesions. Correlation between clinical and BTEP findings could be found only in those patients who presented with signs of trig eminal involvement such as trigeminal neuralgia or dysesthesiae. The a nalysis of the BTEP waveforms showed two distinct types of abnormality - a peripheral type and a central type - suggesting plaques in distin ct locations. Both the BTEP and the BAEP demonstrated a correlation wi th the clinical course of the disease and the condition of the patient at the time of the evaluation. Relapse of the disease was associated with a marked prolongation of the central conduction time in the BTEP and in the BAEP, suggesting the application of such studies to the mon itoring of unstable patients or the evaluation of new therapeutic prot ocols.