Abstracts

Rationale: The clinical spectrum of mutations in the polymerase gamma (POLG) gene of mitochondria is expanding. In addition to the classic Alper's hepatocellular phenotype, seizures are common presenting feature. Seizures types include myoclonic, focal, and generalized tonic clonic seizures. Refractory partial seizures evolving into epilepsia partialis continua should raise the clinical suspicion for POLG mutations. Methods: Retrospective chart review of 2 patients with seizures later diagnosed with POLG mutation. We performed a Pubmed search for reports from 1950-2014 using the following terms: EEG or Electroencephalography and POLG and Alpers and PLEDS/EPC. Results: Patient 1 is a 32 months old girl that presented initially for evaluation of speech regression and ataxia. Shortly after her initial evaluation she presented in status epilepticus described as right upper extremity jerking followed by generalized tonic clonic seizure. Her initial EEG was characterized by generalized irregular polyspikes. During the following months she presented with focal status epilepticus. Her VEEG showed left posterior electrographic seizures. She developed prolonged right upper extremity weakness as a postictal Todd's phenomenon. For her seizure management she required the use of several antiepileptics including Phenobarbital, Levetiracetam, Fosphenytoin, Cloabazam and midazolam drip. Her Brain MRI showed slight nonspecific asymmetry of the temporal horns (Right slight larger than left). Her disease progressed and she ultimately died from respiratory failure. Patient 2 was initially evaluated at 10 months of age due to hypotonia, leukocytosis and transaminitis with failure to thrive. A Brain MRI was suggestive of benign external hydrocephalus. He had REEG done which was normal. Two months later he presented with episodes of staring and eye deviation to left in setting of fever with negative infectious workup including HSV. His EEG showed periodic lateralizing and electrographic seizures from right hemisphere at which time he was loaded with Dilantin, Levetiracetam and Oxcarbazepine. Later EEGs showed Left hemispheric spike and wave discharges occurring in runs at times, diffuse background slowing and disorganization. He is currently G-tube dependent and severely delayed. Both patients were diagnosed with POLG mutation. Chromosomal microarray and routine mitochondrial panels were negative. Conclusions: POLG mutations can cause difficult to control seizures. Cases have been described for POLG mutations causing Occipital lobe epilepsy. Epilepsia partialis continua and very frequent lateralized epileptiform discharges particularly in absence of structural lesion and other clinical features like hypotonia and developmental delay should raise the suspicion for this condition. Early diagnosis has important implications on treatment as valproic acid can induce fatal liver dysfunction and should be avoided.