Prognostic Factors of Patients with Postinfantile Epilepsy and Multiple Independent Spike Foci on Electroencephalography

Abstract

Purpose Multiple independent spike foci (MISF) have been reported to be associated with hypsarrhythmia and slow spikes and waves. However, some patients with MISF demonstrate a good prognosis, such as benign focal epilepsy. This study aimed to elucidate the prognosis of epileptic children with MISF and to analyze the prognostic factors. Methods The subjects were 115 epileptic children aged 1 to 18 years who visited Pusan National University Children’s Hospital between November 2008 and July 2016 and in whom MISF were noted on electroencephalography. We excluded patients with infantile spasms, congenital metabolic diseases, neurodegenerative diseases, or post-encephalitic epilepsy. We retrospectively reviewed participants’ clinical information. Seizure control was defined as no seizures over 6 months at the last visit. Prognostic factors were analyzed in the seizure control (group A; 84 [73%]) and no seizure control (group B; 31 [27%]) groups. Results Generalized seizure (P=0.033), intellectual disability (P<0.001), cerebral palsy (P=0.046), and abnormal background activity and electrodecrements on electroencephalography (P<0.001) were significantly more common in group B. No clinically significant abnormalities were noted on magnetic resonance imaging of the brain. The MISF improved on follow-up electroencephalography in 58 (71.6%) patients in group A versus 10 (35.7%) in group B (P=0.002). Conclusion Despite MISF on electroencephalography, two-thirds of patients had a benign clinical course, particularly those with post-infantile epilepsy and no infantile spasms. The prognostic factors of poor outcomes were generalized seizures, intellectual disability, and abnormal background activity on electroencephalography.

Keywords

• child
• electroencephalography
• epilepsy
• prognosis