Abstracts

As the population ages, more patients are presenting for evaluation for cognitive impairments, particularly memory related deficits. Brain imaging has become the technology of choice in evaluating such complaints, replacing the historical tool of choice, the EEG. Although the prevalence of epilepsy rises with age and is highest in the elderly, identification of affected patients is hampered because clinical seizures in this age group are often subtle, frequently masking the role recurrent epileptiform discharges (EDs) play in producing or exacerbating cognitive and behavioral deficits. In addition, decreased use of the EEG may also have hindered our understanding of the prevalence of EDs in the aging brain and their underlying role as a primary or secondary cause of impairment. Development of reliable markers for the risk of EDs that impact cognition or behavior would improve clinical care., Patients for this study came from the VA Neurobehavior and Memory Disorders Clinics with referring consults indicating a broad array of problems from memory impairment to requests to rule out dementia. Neurological and neurobehavior exams were performed. Clinical criteria for obtaining EEGs included recurrent hallucinations or repetitive types of atypical behavior (e.g., violence). Brain imaging included [ge]1 MRI/patient., Nine patients were evaluated (age range: 63-87; median age: 75). Only two patients (22%) had known epilepsy with rare clinical seizures. All nine patients (100%) had some cognitive deficits or dementia. Six patients (67%) had classic EDs (spikes or sharp waves) on routine EEG. Two patients (22%) had possible EDs consisting mainly of bursting slow waves lasting up to several seconds duration. One patient (11%) did not show EDs. Of five patients having deep white matter (WM) changes and/or a thalamic lacune but no cortical infarct, four (80%) demonstrated EDs. One of the patients with known epilepsy, admitted for psychosis, received antiepileptic drug therapy for recurrent EDs. Following treatment his Mini Mental State Examination score improved from 20/30 to 30/30 and aggressive behavior ended., These findings indicate that deep WM and/or thalamic lesions may disrupt subcortical-cortical circuits, creating areas of cortex with EDs that can be captured by scalp EEG. Our pilot data supports the concept that the presence of such abnormalities on MRI in patients being evaluated for cognitive impairment, abnormal behavior or dementia should prompt consideration for an EEG even in the absence of a history of clinical seizures. Further research is needed to fully characterize the impact of recurrent EDs in the aging brain., (Supported by VA Research Service.)