Abstracts

Rationale: Video-EEG monitoring (vEEG) is the gold standard for diagnosing psychogenic nonepileptic seizures (PNES).  While vEEG is expensive, delayed diagnosis of PNES in turn delays appropriate treatment and stopping inappropriate treatment, tests, and ED visits.  Reducing vEEG duration in the evaluation of patients with suspected PNES would reduce the cost, is less of a burden for patients, and may increase the willingness to order vEEG.  There is little data regarding the number of days necessary and sufficient to detect PNES. Data from our vEEG monitoring unit was used to calculate the frequency of PNES diagnosis during each day of monitoring to clarify necessary length of stay. Methods: Patients who had vEEG from 2011 thru Jan 2014 were included.  Patients were excluded for not completing monitoring or when records did not clearly indicate the when patients had their first seizure (FS).  Data collected included: age, gender, years since first seizure, day of FS, total number of monitoring days, and vEEG results.  The 9 classification categories, based on vEEG reports, are delineated in the Results section. Summary statistics were calculated for descriptive data, frequency of each vEEG result, and frequency of the FS on each day of monitoring.  Due to sample size considerations, comparisons were limited to data from patients with ES and PNES. Results: Two patients were excluded because they left AMA and 8 were excluded because the day that the FS occurred was unclear. The remaining 190 patients were 65% female and 35% male. Reasons for admission were: 1) to assess for PNES in 50%; 2) as part of pre-surgical evaluation in 8%; and 3) for other reasons in 43%.  Age at admission ranged from 18 to 86 (X= 40.6, s.d. = 14.6) and years since spells began ranged from less than 1 to 47 (X= 12.8, s.d. = 12.9). Results of vEEG were: 28% had PNES; 21% had ES; 19% had no seizures and normal EEG; 14% had no seizures but abnormal EEG; 5% had interictal epileptiform activity only; 4% had probable PNES but abnormal EEG; 4% had ES with no change clinically; 3% had seizures that were unclear; and 2% had both PNES and ES.  Days of monitoring ranged from 1 to 12 (X=3.3, s.d.=2.2) for the group as a whole.  Of the 109 patients who had a FS, 62% had a seizure on Day 1, 14% on Day 2, and 12% on Day 3, 5% on Day 4, and 8% occurred on subsequent days. Of the 94 patients admitted for PNES evaluation, 50% had PNES during monitoring and only 2% had ES.  PNES patients were monitored between 1 and 9 days. Of those, 81% had a seizure on Day 1, 10% on Day 2, 8% on Day 3, and 2% on Day 4.  ES patients were monitored between 1 and 12 days; 36% had a seizure on Day 1, 18% on Day 2, 18% on Day 3, 10% on Day 4, 10% on day 5, and less than 10% on subsequent days.   Conclusions: Our data suggest that the vast majority of patients having PNES during vEEG will do so during the first day of monitoring and 90% had their FS by the second day.  Particularly for patients with other risk factors for PNES, even one day of monitoring may result in considerable cost savings and 2 days of monitoring may be sufficient to establish this diagnosis in nearly all patients with PNES. Funding: None