Bithalamic compromise in acute disseminated encephalomyelitis following H1N1 influenza vaccine.

Received 4 July 2010. Received in final form 18 January 2011. Accepted 25 January 2011. A 5-year-old boy was admitted with history of fever, nausea, vomiting and somnolence which had started two days after H1N1 influenza vaccination. Neurological examination showed mild gait ataxia, vertical ophthalmoparesis and brisk deep tendon reflexes. Brain MRI revealed right frontal and bilateral thalamic lesions with increased signal in T2-weighted and flair images (Figs A, B, C, D). Cerebrospinal fluid analysis showed mild lymphocytic pleocytosis. The patient had a marked clinical improvement after oral corticosteroids was commenced. Bilateral thalamic lesions have been reported in 12% of pediatric patients with ADEM. This is the first case of ADEM following H1N1 vaccine reported in Brazil.