Seizures in the elderly: etiology and prognosis

To determine the etiology, early mortality, predictors of prognosis and diagnostic yields of EEG and CT scans of the head in new-onset seizures in elderly patients.

EEG records for the north-central region of Saskatchewan, between 01/94 and 12/95 were reviewed to identify all adults aged 60 years or older with new-onset seizures. Information on demographics, seizure type, etiology, EEG and neuroimaging studies, anti-epileptic treatment and course of epilepsy was obtained by review of medical records and interview with the patient and/or family member.

Of 88 eligible subjects, 61 (69%) were contacted for follow-up, 19 (22%) were deceased (12 of whom who had a serious underlying etiology to their seizures, which was obvious at the time of initial presentation and led shortly to their demise), 4 (5%) were lost to follow-up and 4 (5%) refused participation. Excluding those refusing participation, 74/84 (88%) patients presented with partial or secondarily generalized seizures. Seizures were cryptogenic in 38/84 (45%), and due to stroke in 19/84 (23%). EEGs were abnormal in 61/84 (73%) cases, with epileptiform discharge in 33/84 (39%). CT scans were abnormal in 57/84 (68%) cases with acute pathology in 29/84 (35%). Of the 61 patients participating in the follow-up interview, 54 (89%) were treated with anti-epileptic medication and seizure control was usually successful. Predictors for ongoing seizures were more than 3 seizures at presentation, epileptiform activity on initial EEG and discontinuation of anti-epileptic medication for lack of efficacy.

Prognosis of new-onset seizures in elderly patients is favorable if seizures are not symptomatic of a life-threatening disorder.