Abstracts

Rationale: Metabolic disorders constitute an important cause of neurologic diseases. There are more than 10,000 well-recognized and characterized inherited disorders in man, many of which impact central nervous system function either directly or indirectly. A smaller subset of nearly 200 disorders is associated with seizures and epilepsy. Here we report neurometabolic disorders in adolescent and children with seizure in Taiwan. Methods: From 1978 to January 2008, we collected cases proven as neurometabolic disorders. The diagnosis was made by characteristic clinical features, specific laboratory results of blood tandem mass, blood amino acids and urinary organic acids, enzyme assays, tissue biopsies, genetic analysis and specific magnetic resonance (MR) imaging and MR spectroscopy findings. We retrospectively analyzed the epileptic seizures in patients with neurometabolic disorders. Results: Total 178 cases, aged from 1 day to 15 years, were enrolled. 92 out of 178 cases (51.7%) presented with seizure: 47 out of 92 (51.1%) with seizure as an initial clinical feature, 45 (48.9%) with seizures during the course of illness, 53 (57.6%) were refractory to antiepileptic drug therapy. Concerning the seizure types, 62 out of 92 (67.4%) were generalized seizures, including generalized tonic seizure, generalized tonic-clonic seizures, and myoclonic seizures, 20 (21.7%) were partial seizures, 8 (8.7%) were mixed seizure types and 2 (2.2%) were epileptic syndrome, early myoclonic encephalopathy (EME). The first three intractable seizures in neurometabolic disorders were disorders in heavy metals (7/8; 87.5%), lysosomal storage disorders (7/9; 77.8%) and mitochondrial disorders (26/39; 66.7%). In our study, specific electroencephalographic (EEG) features in neurometabolic disorders included comb-like rhythm, vanishing EEG, high voltage activity, marked photosensitivity, burst-suppression, and hypsarrhythmia. Conclusions: Epileptic seizures in adolescent and children are often part of the clinical picture of inherited metabolic disorders. In our series, 51.7% cases had seizures. Some patterns of clinical presentations and/or EEG findings may indicate underlying neurometabolic diseases. So neurometabolic workups are necessary in patients with abnormal neurologic findings.