Abstracts

Rationale: Some patients with myoclonic seizure (Sz) or atonic Sz do not respond to antiepileptic drugs (AEDs) for this Sz. Sz of negative motor area (NMA) origin shows myoclonic or atonic Sz, motion arrest or inability to speak as an inhibitory Sz. NMA consists of negative supplementary motor area (NSMA) and primary negative motor area (PNMA). The Sz semiology, interictal scalp EEG features and medical treatment of NMA Sz have not yet been elucidated. We studied these issues. Methods: Patients who showed myoclonic Sz, atonic Sz or motion arrest as a sole Sz or a part of multiple Szs and did not responded to VPA, CZP, CLB, ESM or AZM were studied by using interictal scalp EEG, MR imaging, and some of long-term video-EEG monitoring, interictal and/or ictal ECD-SPECT, interictal FDG-PET, and MEG. 27 cases of NMA Sz were selected and 23 subjects were prospectively treated by the author (KS) for over one year. Efficacy of a new drug was estimated by Sz reduction rate after adding or switching it by unblinded and non-randamized fashion. Results: The NMA Sz symptoms included motion arrest in 7 cases, atonic head nodding in 4 cases, atonic slow falling or landing on his/her rear in 22 cases, and myoclonic events in 7 cases. 16 cases had more than one inhibitory Sz symptom. Only 4 cases had NMA Sz symptoms alone. 18 cases had NSMA and supplementary motor area (SMA) Sz symptoms, 3 cases had PNMA and anterior frontopolar (AFP) Sz symptoms, and 2 cases had PNMA and dorsolateral (DL) Sz symptoms. Interictal EEG showed epileptiform discharges over the frontal-midfrontal (Fz) area with or without frontopalar area in 13 cases, frontal-central-Fz-midcentral (Cz) area in 4 cases, frontopolar-frontal area with or without anteriotemporal area in 6 cases and frontal-central area in 4 cases. 20 cases showed generalization or burst of generalized discharges as well. 2 of 3 cases with NMA Sz alone ceased with ZNS and ZNS+CLB in one each, and reduced by >75% with ZNS or CLB in one each. Among 15 cases with NMA and SMA Szs, Sz ceased with ZNS in 7, PB in 2, ZNS+PB in 2 and CLZ+VPA in one case, and reduced by >75% with ZNS in 4, bromide in one, and VPA in one case. Among 3 cases with NMA and AFP Szs, Sz ceased with CBZ in 2 and with ZNS in one case, and reduced by >75% with CBZ or CLB in one case each. Two cases with NMA and DL Szs became Sz free with PB or bromide in one each. Conclusions: NMA Sz showed myoclonic or atonic Sz or motion arrest of frontal origin, but usually accompanied with other Sz symptoms of the adjacent areas, and sole NMA Sz were rare. Epileptiform discharges on interictal EEG were dominated over the frontal area in all cases, and most cases involved in the Fz, Cz areas but some cases did not, which were responsible for NSMA Sz and PNMA Sz, respectively. Frequent generalization might cause misdiagnosis and maltreatment of NMA Sz as generalized Sz. NSMA Sz well responded to ZNS, PB or bromide which is usually effective for SMA Sz and PNMA Sz responded to CBZ or CLB which is effective for motor cortex Sz. It seems that NMA Sz respond to AEDs effective for the Sz of the adjacent areas to NMA.