Early-onset versus typical childhood absence epilepsy; clinical and electrographic characteristics

PURPOSE Childhood absence epilepsy (CAE) is characterized by absence attacks with stereotyped electrographic discharges. Epidemiologic data concerning early-onset CAE is scarce. We tried to specifically analyze the early-onset CAE and compare it with typical CAE. METHODS In this retrospective study, all patients with a clinical diagnosis of CAE were recruited in the outpatient epilepsy clinic at Shiraz University of Medical Sciences from 2008 to 2011. We considered the age of onset at four years or earlier as early-onset and above four years as typical CAE. Age, gender, age at seizure onset, seizure type(s), epilepsy risk factors, and EEG findings of all patients were registered routinely. Statistical analyses were performed using Chi square and Fisher's Exact tests. RESULTS Forty-six patients were diagnosed as having CAE. Sixteen patients (35%) had early-onset and 30 (65%) patients had typical CAE. Sex ratio (female to male) in early-onset was 7:9 and in typical CAE was 19:11 (P=0.2). Generalized tonic-clonic and myoclonic seizures were reported in both early-onset and typical CAE. The differences were not statistically significant. Epilepsy risk factors were similarly reported in both conditions. The EEG findings were similar in both groups. CONCLUSION We did not observe any significant differences between early-onset and typical childhood absence epilepsies with respect to the demographic, clinical and electroencephalographic characteristics.