Management of West syndrome in a patient with methylmalonic aciduria.

Infantile spasms (or West syndrome) occur occasionally in patients with branched-chain organic acidurias. We describe a patient diagnosed with methylmalonic aciduria at 4.5 months of age during an episode of metabolic decompensation. The child was developmentally delayed and hypotonic; his electroencephalography (EEG) showed hypsarrythmia and brain magnetic resonance imaging (MRI) demonstrated moderate abnormalities in the globi pallidi. Following the failure of vigabatrin and lamotrigine to control the spasms, hydrocortisone was introduced. Methylmalonic acid excretion increased at the onset of steroid therapy but was rapidly corrected with transient protein restriction and initiation of metronidazole therapy. Full control of spasms and hypsarrythmia permitted the discontinuation of hydrocortisone therapy a year following its initiation. Tone and development improved although the latter remained delayed. This case illustrates the importance of screening for inborn errors of metabolism in seizure disorders, and that, although challenging, the management of methylmalonic aciduria with concurrent steroid therapy is possible and beneficial.