Intraoperative acidosis related to chronic zonisamide therapy.

Abstract

Zonisamide is a novel anticonvulsant agent used in the treatment of partial and generalized seizures in children and adults. In addition to its anticonvulsant effects, zonisamide inhibits carbonic anhydrase and may result in a chronic, non-anion gap metabolic acidosis. We present an 8-year-old girl with medically intractable epilepsy and Lennox-Gastaut syndrome who presented for a right craniotomy and functional hemispherotomy. Intraopera- tively, she was noted to have a metabolic acidosis that was eventually determined to be from chronic therapy with zonisamide. The intraoperative differential diagnosis of metabolic acidosis is presented, an approach for diagnostic investigation presented, and treatment options outlined.

Keywords

• zonisamide
• anticonvulsant therapy
• metabolic acidosis
• anion gap.