Idiopathic cortical myoclonus restricted to the lower limbs: correlation between MEPs and Tc-99m-ECD single photon emission computed tomography activation study

We report a 63-year-old woman with cortical reflex myoclonus restricted to the bilateral lower limbs. Somatosensory evoked cortical potentials to post erior tibial nerve stimulation were enlarged with C-responses. Jerk-locked back averaging of the EEG identified a cortical spike related to myoclonic jerks. Motor evoked potentials recorded from the abductor hallucis muscle s howed an exaggerated late response. These findings suggest hyperexcitabilit y of the sensorimotor cortex. Tc-99m-ECD single photon emission computed to mography (SPECT) after stimulation of the posterior tibial nerve showed inc reased perfusion in the contralateral peri-Rolandic area which corresponded to the hyperexcitable region. A SPECT activation study as well as MEPs the refore can be employed to determine the hyperexcitable region in cortical m yoclonus. (C) 1999 Elsevier Science B.V. All rights reserved.