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.