Interictal epileptiform discharges in new-onset epilepsy among older adults

Background The incidence of epilepsy is highest in older adults and exceeds that observed in children. Seizure disorders are also more common among older adults. However, there are few reports of interictal epileptiform discharges in new-onset epilepsy among older adults. Aim To investigate the rate of interictal epileptiform discharges in elderly patients with new-onset epilepsy. Methods We defined elderly patients with new-onset epilepsy as those who developed epilepsy after the age of 65 years. We reviewed the interictal electroencephalographic characteristics of patients with new-onset epilepsy treated between April 2005 and December 2011 at a tertiary referral center. Both outpatients and inpatients were included in this study. Epilepsy was diagnosed on the basis of clinical history, scalp-recorded electroencephalography, physical findings, brain 3.0-T magnetic resonance imaging/computed tomography, single-photon emission tomography and neuropsychological evaluation. Epilepsy and seizure classifications, and age of onset were also reviewed. Results We included 112 patients (58 men and 54 women) in this study. The mean age of seizure onset was 73.5 ± 6.7 years. Interictal epileptiform discharges were detected in 82 patients (73.2%). Temporal lobe epilepsy (odds ratio 6.3, P = 0.004) and complex partial seizures (odds ratio 8.0, P = 0.033) were associated with interictal epileptiform discharges. Conclusion Interictal epileptiform discharges were present in 73.2% of the elderly patients with new-onset epilepsy in our cohort, which was higher than the previously reported rate. Temporal lobe epilepsy was the most frequent epilepsy diagnosis among the interictal epileptiform discharge-positive patients.