Abstracts

Rationale: Although clinical features help distinguish epileptic seizures (ES) from nonepileptic pseudoseizures (PS), continuous video-EEG (CV-EEG) is necessary for diagnosis. Artifacts, rare events, or availability may leave diagnosis ambivalent or infeasible. Regularity of convulsive motor activity may add additional diagnostic utility. Methods: Patients between ages 16-60y were admitted for CV-EEG diagnosis of convulsions. Spells selected for analysis consisted of generalized gross motor activities. Movements were recorded with the use of a wrist-mounted accelerometer. The temporal profile of regularity of movements were characterized with approximate entropy (ApEn) and peak-to-peak amplitude of repeated patterns (PPARP). Results: 19 PS and 15 ES were evaluated. ES were significantly more irregular than PS (mean ApEn ES=1.78, PS=1.38, p=0.0027; mean log PPARP ES=1.72, PS=2.80, p=0.005 Mann-Whitney U test). Threshold values for the minimum ApEn during an event = 1.4 distinguished ES from PS with Se=86% and Sp=74%; mean log PPARP threshold =1.6; Se=73%, Sp=84%.Conclusions: Two measures of regularity of movements obtained with limb accelerometry distinguished convulsions arising from ES from PS with reasonable accuracy in this pilot study. Accelerometry may be developed into a useful adjunct in the diagnosis of convulsions.