The neurophysiology and seizure outcomes of late onset unexplained epilepsy

Objective To investigate neurophysiologic and neuroimaging characteristics of patients with late onset unexplained epilepsy (LOUE). Methods We performed a retrospective chart review of elderly patients with ICD9 diagnosis codes consistent with epilepsy/seizures. Inclusion criteria included unprovoked seizures, and absence of cortical lesions on magnetic resonance imaging (MRI). Electroencephalograms (EEGs) findings were also analyzed. MRI images were scored for degree of white matter hyperintensities (Fazekas Scale) and mesial temporal atrophy (MTA). Vascular risk factors, and Framingham Heart Study general cardiovascular disease (FHS-CVD) risk scores were compared to controls from the Harvard Aging Brain study (HABS). Results We identified 224 LOUE patients and 8% were drug resistant. Epileptiform abnormalities were captured on EEG in 35%. The location was temporal with left sided predominance in 49%. Fazekas scale consisted of 25% beginning of confluent lesions, and 10% large confluent lesions. MTA scores consisted of 21% moderate-severe hippocampal atrophy. LOUE patients had on average a 2.3% (adjusted), 7.4% (unadjusted) increased FHS-CVD score. Conclusions Our findings highlight LOUE as pharmacosensitive and left temporal predominant. Given the higher prevalence of vascular risk factors, investigations are needed to study their role in pathophysiology. Significance Physicians caring for patients with LOUE should evaluate for vascular risk factors and investigate the presence of hippocampal atrophy.