Abstracts

Valproic acid (VPA) can cause hyperammonemia alone or in combination with other agents. Hyperammonemia is associated with EEG abnormalities including triphasic waves, high amplitude delta and generalized spike and wave. Hyperammonemia can also lead to cerebral edema, coma and death. We hypothesized that refractory VPA induced hyperammonemia in the setting of status epilepticus (SE) could be treated with hemodialysis (HD) and would lead to improvements in the EEG. Two patients in SE treated with pharmacologic coma in addition to standard antiepileptic drugs developed refractory hyperammonemia secondary to VPA. HD was undertaken to lower ammonia (NH3) levels. NH3 levels were measured pre and post HD during continuous EEG monitoring. EEG patterns were analyzed. Other laboratory parameters were measured. Marked improvements in NH3 levels were noted after each round of HD. Additionally, the generalized, periodic triphasic waves seen before HD were replaced by a pattern of diffuse slowing. Permanent resolution of the hyperammonemia and its associated EEG abnormalities came only after discontinuation of the VPA. HD can be an effective method for the treatment of VPA induced hyperammonemia in the setting of SE. Improvements in the EEG findings after HD may help to distinguish triphasic waves secondary to hyperammonemia from other more malignant patterns in SE.