Abstracts

Rationale: Pyridoxal 5 -phosphate (PLP) dependent epilepsy is a relatively newly recognized disorder which is diagnosed by cerebrospinal fluid (CSF) analysis and gene testing. However, the electroencephalographic (EEG) patterns that could potentially raise the index of suspicion of this syndrome have not been characterized to date. Here we report EEG findings of two such patients. Methods: Patients were included, if they had seizures refractory to antiepileptic drugs, decreased PLP levels in CSF, and became seizure free after taking PLP. Pyridoxamine 5 -phosphate oxidase (PNPO) gene sequencing, performed on one patient, confirmed the presence of a mutation in that gene. EEGs performed before starting PLP were reviewed and a retrospective chart review was done. Results: Case 1: A 3 year old African American boy who had, as of the age of 2 years, recurrent complex partial seizures that occurred up to four per day and were refractory to levetiracetam, carbamazepine and pregabalin. EEG at age 3 revealed, interictally, a background that achieved 8Hz with frequent, bilateral independent, C3, C4, T3, and T4 spikes, more on the left, in wakefulness as well as continuous 2-2.5Hz generalized spike and slow wave of higher amplitude over C3 and C4 in sleep (consistent with electrical status epilepticus in sleep) and ictally, runs of left hemisphere spike slow wave discharges, predominantly C3 and T3, usually for 5-15 seconds. Case 2: A 2 month old Hispanic boy who had neonatal status epilepticus at the age of 10 hours and subsequent recurrent generalized tonic-clonic seizures (2-8/day) over the next several weeks. His seizures were refractory to phenobarbital, fosphenytoin and lorazepam. When first seen by us, EEG on day 18 of life revealed bilateral, independent paroxysmal multifocal sharp waves, mostly over T4 interictally. These discharges often occurred in runs lasting from a few seconds to few minutes. There was also excessive discontinuity of the background. Conclusions: We observed the following pre-treatment EEG manifestations of PLP dependent epilepsy: 1) Interictally: frequent, multifocal, independent spike or sharp wave discharges, 2) Interictally and ictally: runs of unilateral and repetitive spikes/slow waves, and 3) Electrical status epilepticus in sleep. These EEG findings, in the appropriate clinical setup, should raise the suspicion of PLP dependent epilepsy.