The start-stop-start phenomenon in scalp-sphenoidal ictal recordings

The start-stop-start (SSS) phenomenon is an apparent abortive ictal onset separated from the main seizure discharge. It was previously described in seizures recorded with subdural electrodes. We have observed this phenomenon in scalp-sphenoidal ictal recordings as well. We retrospectively reviewed 435 seizures recorded with scalp-sphenoidal electrodes from 61 patients with temporal lobe epilepsy. We found SSS onset in 15 seizures of 8 patients, representing 26% of these patients' seizures. The first ''start'' usually had a narrow field, typically in the sphenoidal electrode. The mean duration of the first ''start'' was 11 sec and that of the stop 8 sec. The restart had a different morphology and frequency in 87% and had a wider field in 67% of seizures. The clinical onset followed the first start and preceded the restart in most of the seizures. In 1 patient, 1 seizure with SSS was correctly localized and lateralized, whereas 5 of 7 without SSS were falsely lateralized. The recognition of the SSS phenomenon may improve the accuracy of seizure localization in scalp-sphenoidal recordings.