Epileptic negative myoclonus: SPECT, PET, and video/EEG studies and the dramatic effects of levetiracetam.

An 18-year-old woman presented with epileptic negative myoclonus (ENM) as her major seizure pattern for 4years. Her seizures were characterized by intermittent postural lapse of the right limbs for a period of hours to 2 days. Ictal electroencephalography (EEG)-electromyography showed a silent period that was time-locked to generalized spike-wave discharges. Video/EEG monitoring demonstrated marked improvement of ENM after oral administration of levetiracetam. Cranial magnetic resonance imaging was normal, but 2-deoxy-2-[(18)F]fluoro-d-glucose positron emission tomography during frequent ENM showed hypometabolism in the left frontoparietal cortex. Technetium-99m-ethyl cysteinate dimer single-photon emission computed tomography revealed hyperperfusion over the left parietal cortex and putamen. Here, we document the short-term effects of levetiracetam in this subject with nearly isolated ENM and the neuroimaging results during ENM. Long-term follow-up is in progress to evaluate the clinical evolution and long-term effects of levetiracetam on ENM.