EEG Observations in Elderly With New Onset Seizures

Abstract

The authors evaluated the spectra of EEG observations in elderly patients with new onset seizures and correlated it with clinical, laboratory, and imaging findings. This prospective study involved 201 elderly individuals (age: 68.0 ± 7.5 years; male:female = 1.8:1) who manifested with new onset seizures. Data regarding clinical, laboratory, routine EEG (n = 201), and imaging (computerized tomography = 201; MRI = 43) observations were noted. Details of EEG findings were analyzed and correlated with other parameters. Visual analysis of scalp EEG in 124 patients (61.7%) was abnormal, and the abnormalities included asymmetric background activity (3%) and diffuse slowing (32.8%) and focal slowing (7%) of the background activity. Dominant α-activity was more common in remote symptomatic group. Higher frequency of alpha waves was observed in patients with cryptogenic epilepsy compared with those with acute symptomatic epilepsy. Diffuse slowing and excess of β-fast activity were observed more often in acute symptomatic group. Epileptiform activities were evident in one third of patients and were noted in the temporal (38.8%) and frontotemporal (23.9%) regions. In univariate analysis of patients with and without EEG abnormalities, female gender, cluster attacks/status epilepticus, acute symptomatic epilepsy, longer duration of postictal state, lower Glasgow coma scale score, lower Mini-Mental State Examination score, focal deficits, diffuse edema (computerized tomography), and focal lesions (MRI) were significantly associated with abnormal EEG. Presence of epileptiform activity predicted the use of polytherapy (P = 0.004, odds ratio = 3.3). The significant factors associated with an abnormal EEG (multivariate) were female gender (P = 0.03, odds ratio = 2.32), lower Glasgow coma scale score (P = 0.03, odds ratio = 0.70), and lower frequency of α-waves (P = 0.04, odds ratio = 0.56). Scalp EEG was abnormal in approximately two thirds of elderly patients, with the presence of epileptiform activities in one third of patients. Abnormal EEG significantly correlated with lower Glasgow coma scale score, suggesting its role in prognostication.