Abstracts

Rationale: Rhythmic ictal nonclonic hand (RINCH) motions were described as a contralateral sign in temporal lobe epilepsy. However, there has not been a large study evaluating the occurrence of this sign in all monitored patients. The purpose of this study was to evaluate the occurrence of RINCH in a large population of patients admitted in an epilepsy monitoring unit (EMU) where this sign is routinely recognized and reported.Methods: We searched our EMU reports from 2006 to 2014 for the terms “RINCH” and “rhythmic hand” movements or motions. We reviewed all video recordings of seizures with RINCH to verify the occurrence of RINCH as previously defined. We also reviewed corresponding EEG tracings for lateralization and localization of seizure onset. We recorded lateralization of RINCH and its timing in relation to seizure onset, as well as to the overall localization of the epileptogenic zone based on all data including semiology and imaging. We evaluated the incidence of RINCH in epilepsy for the period 2013-2014.Results: There were 131 seizures in 71 patients with RINCH. RINCH occurred in 8.5% of EMU patients with recorded seizures during a 2-year period from 2013 to 2014. Overall seizure localization was temporal in 57 patients, fronto-temporal in 3 patients, extratemporal in 7 patients (6 frontal and 1 occipital), and non-localizable in 4 patients. The most common RINCH movements in descending order were: hand opening and closing (37%), finger rubbing (26%), milking motions (14%), pill rolling (7%), finger flexion/extension (10%), Other (6%). RINCH lateralized to the contralateral hand in 93.8% of patients (61/65). Of the four patients with ipsilateral RINCH, three had bi-temporal electrographic seizure onsets, and one had other seizures with RINCH in the contralateral hand. Mean RINCH latency from seizure onset was 34.48 seconds (SD=27.66) in temporal lobe epilepsy and 10.31 seconds (SD=9.77) in definite or probable frontal lobe epilepsy (p=0.008).Conclusions: RINCH is a distinct early ictal clinical sign which is almost always contralateral. When RINCH is ipsilateral to seizure onset, the possibility of false lateralization of scalp ictal onset should be considered. Although RINCH is most common in temporal lobe epilepsy, it may occur in extratemporal epilepsy as well. RINCH latency from seizure onset was significantly shorter in extratemporal epilepsy.