Abstracts

Rationale: Periodic lateralized epileptiform discharges (PLEDs) have been described by Dr. Chatrian. It has been associated commonly with acute stroke in adults and infections (e.g.HSV) in children. We report a patient who developed PLEDs over one hemisphere and then over a period of 2 years it shifted from one to another. Review of literature did not provide more information on the shifting PLEDs (PLEDs form one hemisphere to another). Methods: This is an 8 year old boy with a history of seizures since age 1. Initially, his seizures were complex partial characterized by staring spells and stiffening lasting seconds to minutes. Since Mar 07, he has complex partial seizure followed by post ictal transient (< 1 month) hemiparesis (either right or left) and ataxia. His seizures are poorly controlled. Currently, he is taking topiramate, valproic acid, levetiracetam, clonidine and clorazepate. There is a history of maternal use of cocaine during pregnancy. He has a global developmental delay (language > motor) with autistic features. The patient presented with increased frequency of seizures with similar semiology during the hospitalizations. Following is the summary of EEGs and imaging studies done during those hospitalizations. Results: 2002-2006 EEG-multifocal spikes (left frontal, left parietal, bifrontal and right posterior quadrant) and MRI- unremarkable. 3/06 EEG-pseudoPLEDs and also electrographic seizures in the right hemisphere. MRI- T2 signal changes in the right cerebral hemisphere: postictal state or viral encephalitis. 4/06 and 6/07 EEG- spikes from right hemisphere. 8/07 EEG- pseudoPLEDs on the left hemisphere. 9/07-10/07 EEG-pseudoPLEDs on the right hemisphere and MRI- abnormal signal changes in both thalamus. MRS and MRA- normal. 12/07 EEG-spike over the right and MRI-increased T2 signal in the left thalamus and resolved abnormal signal in the right thalamus. 1/08 subclinical ictal events originating in the left posterior quadrant. Work up for seizures and global developmental delay include: several MRI brain, genetic tests and consultation, metabolic work (including mitochondrial disorders), several attempts to look for CNS infections. Conclusions: This is 8 year old boy with a history of intractable seizures; global developmental delay of unknown etiology has shifting PLEDs over a period of 2 years. PLEDs classically have been first described by Chatrian in 1964: unilateral focal spike or sharp wave complexes with periodic appearance at rate of 1-2 seconds and occurs at regular interval and persists greater than 10 minutes or continuous. In adults most commonly seen in patients with stroke, CNS infections, neoplasm, head trauma. In children, common causes are infection, anoxic encephalopathy, and metabolic disorders. PLED is a transient EEG pattern. It disappears in less than 4 weeks, although chronic PLEDs have been described in patients with TS,abscess, porencephalic cyst. We report a case where a patient presented with a cluster of seizures and EEG showed shifting PLEDs without any apparent cause. Is it a presentation of a single disease or different?