Can short-term video-EEG substitute long-term video-EEG monitoring in psychogenic nonepileptic seizures? A prospective observational study.

BACKGROUND: Psychogenic nonepileptic seizures (PNES), the commonest nonepileptic event, represent 20-30% of drug-resistant epilepsy. Correct identification of PNES avoids unnecessary hospitalization and exposure of antiepileptic drugs (AEDs), and helps implement appropriate psychological treatment. Long-term video-electroencephalography (LTVEEG) is the gold standard test to diagnose PNES. However, in a poor-resource country like India, hypothetically, short-term video-electroencephalography (STVEEG) may substitute it, as its usefulness is established in attack disorders.

OBJECTIVE: The objective of this study was to evaluate effectiveness of STVEEG in PNES and to look into their clinical profile and outcome.

DESIGN/METHODS: Consecutive cases of PNES diagnosed with STVEEG or LTVEEG during 2015-16 (two years) were enrolled. All cases were followed for 12 months or more. Detailed clinical evaluation was done including demography, semiology, coexisting anxiety/depressive disorders, and seizure frequency at time of first diagnosis and follow-up. The PNES were classified as Type I hypermotor, type II hypomotor, and type III unclassified/mixed. Favorable outcome was defined as seizure freedom or >50% reduction in seizure frequency while unfavorable outcome was defined as <50% reduction in seizure frequency on follow-up at 6 and 12 months.

RESULTS: Among 57 patients with PNES [median age of onset 24 years (10-69 years), F:M ratio = 7:3)], STVEEG ± induction could record event(s) in 80.7% while the rest required LTVEEG to confirm diagnosis. Among 82 events analyzed, the mean ± 2 standard deviation (SD) duration of events was 5'14″ ± 13'4″. Sixty-two (75.6%) and 10 (12.1%) events were hypermotor and hypomotor respectively, while 10 (12.1%) were unclassified/mixed. Forty-five (79%) patients had pure PNES, while 12 (21%) had coexistent epilepsy. Forty-nine (86%) and 54 (94.7%) patients had statistically significant reduction of seizure frequency (favorable outcome), at 6 and 12 months of follow-up respectively, while the rest had an unfavorable outcome.

CONCLUSIONS: The STVEEG has a remarkably good yield in diagnosing PNES, and it may be used when LTVEEG is not feasible. However, further studies are needed to show if it can substitute LTVEEG in PNES.