A Case of Vigabatrin Toxicity Mimicking Bilateral Thalamic Infarcts on MRI

A 20-month-old female with a past medical history of tuberous sclerosis, epilepsy, and infantile spasms treated with vigabatrin presented for surveillance MRI for multiple brain hamartomatous lesions and subependymal nodules. MRI showed new restricted diffusion to bilateral thalami and globi pallidi. This finding was concerning for bilateral thalamic strokes, with differential to include infection, metabolic etiologies, or toxic injuries. Without focal or diffuse neurologic symptoms or additional MRI lesions to suggest an acute or chronic pathology, it was determined the MRI signal changes were likely induced by vigabatrin. Vigabatrin therapy was continued, and a repeat MRI 17 months later showed a resolution of the diffusion restriction with no residual sequelae. Vigabatrin-induced MRI abnormalities are an uncommon adverse effect of therapy for infantile spasms, with adverse events being most common in young infants. It is crucial to consider this adverse drug effect in an asymptomatic patient presenting with these MRI lesions as the findings are otherwise suggestive of a serious disease process, such as an inborn error of metabolism, requiring expensive and invasive workup.