A 10-year-old girl with a 4-month history of abnormal gait and dysarthria had bilateral external ophthalmoplegia, dystonia, and altered mental status. MRI showed a characteristic “bat-wing” appearance and increased signal involving the medial nucleus of the thalamus, basal ganglia and cerebellum, suggesting biotin-responsive basal ganglia disease. Immediate improvement followed biotin and thiamine therapy. Repeat MRI showed resolution of vasogenic edema but residual atrophy and gliosis in the basal ganglia. The disease is autosomal recessive with SLC19A3 gene mutation, related to thiamine transporter-2 deficiency. 
COMMENT. The authors propose that biotin-responsive basal ganglia disease be considered in a case of unexplained acute dystonia, external ophthalmoplegia, confusion and encephalopathy.