Abstracts

Rationale: Seizures are a common co-morbid condition in patients with dementia, however their characteristics in this patient population have been poorly described. The purpose of this study is to analyze seizures in patients with a diagnosis of dementia, determine the relationship between seizure onset and dementia onset, and define seizure characteristics and neurophysiologic findings. Methods: A retrospective chart review of outpatient and inpatient records using ICD 9 diagnosis codes consistent with seizures and those with dementia were used. Exclusion criteria included: presence of structural lesions, infectious or paraneoplastic syndromes, seizure onset >5 years prior to cognitive symptoms, and a history of developmental delay. The data collected included clinical information related to dementia (onset, diagnosis) seizures (semiology, age of onset, cognitive function at onset, medications), and EEG findings. Results: A total of 1106 patients were identified. Of these 1034 were excluded: 353(34.1%) due to structural lesions or provoked seizures, 350 (33.8%) due to an unclear diagnosis of seizures or dementia, 232 (22.4%) insufficient information, 40 (3.8%) developmental delay, 39 (2.8%) remote seizures, and 19 (1.8%) Down Syndrome. Seventy-two patients fulfilled the study criteria. They were followed for a period of 81.5 months overall, and 47.2 months after their first seizure. Average age at cognitive symptoms was 68.1 (34-85) years, and average age at seizure onset was 73.1 (43-92) years. Seizures either occurred prior or followed the cognitive symptoms by an average of 5.0 years (-3 to 17 years). At the time of the first seizure, 2(3%) were felt to be cognitively normal, 18 (25%) had mild cognitive impairment, and 52 had dementia (72%) The initial seizure semiology was focal with altered awareness in 39 (56%), focal without altered awareness in 3 (4%), and generalized tonic clonic (GTC) in 28 (40%). GTC was noted in the disease course in 41 (59%). Final diagnosis was probable or definite Alzheimer's disease (AD) in 63 (87%) patients, 4 (6%) probable Lewy body Dementia, 4 (6%) probable fronto-temporal dementia (6%), 1 (1%) vascular dementia. EEG at presentation showed focal slowing in 20 (38%), epileptiform abnormalities in 15 (30%), and seizures in 2 patients. The patients had a mean of 2 (1-5) EEGs and an epileptiform abnormality was noted in 18 (34%). Of the patients who had at least 1 year of follow up, 7 (13%) continued to have seizures. At last follow up the mean number of seizure medications was 1 (0-3). A difference was noted in time to seizure onset between early onset dementia (age <65) and late onset dementia patients with mean 7.0 years vs. 4.0 years respectively (p<0.05). Conclusions: Unprovoked seizures can precede or occur after the onset of dementia especially with underlying AD pathology. Epileptiform EEG findings are seen in 33% of the cases, and the majority of patients are controlled with medications. The time to seizure onset is longer in patients with early onset dementia.