PURPOSE: Severe myoclonic epilepsy in infancy (SMEI) seems to be more common than realized, because it is often overlooked. In addition, the prognosis is poor despite of recent advances of antiepileptic treatment. This study is intended to provide better identification and treatment of SMEI by reviewing our experiences. METHOD: From April 1995 to September 2002, clinical and electrophysiologic features were reviewed for 18 patients with SMEI, who were diagnosed at epilepsy center, Inje University Sang-gye Paik Hospital. RESULTS: 1) Seizure onset age was 5.1+/-2.8 months (mean+/-SD) old. 2) Onset of febrile seizure was from 2 to 11 months of age (7.8+/-3.0 months) and febrile status epilepticus was also noted in 9 patients (50%). 3) Initial afebile seizure was noticed in 11 patients (61.1%). 4) Various types of seizures were manifested durign the patient's clinical courses 5) Myoclonic seizures were started from 7 to 48 months of age (26.5+/-12.1 months) and persisted in 14 (77.8%) patients. 6) Four patients (22.2%) had photosensitivity. 7) Mitochondrial cytopathy was suspected in 8 patients, and complex IV deficiency was confirmed in 1 patient. 8) Ketogenic diet was effective in 8 patients (61.5%) with seizure reduction more than 50% among 13 patients. 9) All sixteen patients who could be followed up for more than 12 months, showed normal initial development, and subsequently, all of them showed progressive delvelopmental delay with mild degree in 4 patients (22.2%), moderate degree in 7 patients (38.8%), and severe degree in 4 patients (22.2%). CONCLUSION: SMEI is one of the intractable childhood epileptic syndromes with variable clinical seizures and progressive developmental declining. SMEI should be paid more attention in epilepsy clinic for accurate diagnosis and adequate antiepileptic treatment including ketogenic diet.
Age of Onset ; Cytochrome-c Oxidase Deficiency ; Diagnosis ; Epilepsies, Myoclonic* ; Epilepsy ; Humans ; Ketogenic Diet ; Prognosis ; Seizures ; Seizures, Febrile ; Status Epilepticus