Abstract: Objective To study the electrical stimulation motor evoked potentials in Arnoid Chiari malformation.Methods Electrical stimulation motor evoked potentials were recorded in 30 cases with Arnoid Chiari malformation proved by MRI.Results Abnormality rate of MEP was 96.7%,and the abnormal patterns mainly consisted of the delay of latency and the delay of central motor conduction time(CMCT). The change of MEP was connected with myodynamia and the type of Arnoid Chiari malformation .Conclusions The change of MEP is more sensitive than clinical change, and can indicate the damage of the motor function objectively and quantitatively, and MEP can be used as an objective criterion for surgical effect, and can predict the recovery of motor function.

Key words: motor evoked potential, Arnoid Chiari malformation, microsurgery, pyramidal tract