Motor evoked potentials by transcranial electric stimulation in masseter muscles in amyotrophic lateral sclerosis / 中华神经科杂志

ABSTRACT

Objective To study the motor evoked potential (MEP) evoked by transcranial electric stimulation in the masseter muscles of patients with amyotrophic lateral sclerosis (ALS), and to compare the results obtained from a control population, so as to establishe a method to evaluating the impairment of corticobulbar projections in ALS.Method Transcranial electrical stimulation was used in 20 patients with ALS and 30 matched normal control.Central motor conduction time (CMCT) was calculated.Results Responses to direct activation of the trigeminal motor root (R-MEP) were able to be recorded in all ALS.The latency and amplitude of R-MEP was (3.44?0.53) ms and (2.79?2.19) mV respectively.They had nonsignificant differences as compared to the controls.Responses to activation of corticobulbar descending fibers (C-MEP) were absent or delayed in 12 ALS patients, and CMCT was significantly prolonged ( P