Latency to first psychogenic nonepileptic seizure upon admission to inpatient EEG monitoring: evidence for semiological differences.

Two hundred sixteen consecutive patients diagnosed with psychogenic nonepileptic seizures (PNES) admitted to the epilepsy monitoring unit at our institution over a 4.5-year period were retrospectively identified. PNES were classified into four semiological subcategories: major motor (n=123), minor motor (n=38), akinetic (n=32), and subjective/experiential (n=23). The median latency to first PNES for the entire population was 7 hours (range: <1 to 207 hours), confirming previous observations that the latency to first PNES on admission is often <24 hours. The novel observation is that latency to first PNES was dependent on type. The median latency to first PNES was significantly prolonged in both the minor motor (median=21 hours) and subjective/experiential (median=22 hours) groups as compared with the major motor (median=5 hours) and akinetic (median=4 hours) groups. Thus, patients with one of these two subtypes may require longer admissions to capture the event of interest and confirm the diagnosis.