Biotin-thiamine-responsive encephalopathy, also known as biotin-responsive basal ganglia disease, is characterized by high T2 signal in the basal ganglia (caudate and putamina), which is reported as a typical feature of the disorder. Brain magnetic resonance imaging in our patient, who presented with irritability, poor feeding and prolonged seizures, found multiple areas of restricted diffusion in the cerebral cortex and thalami leading to an initial diagnosis of a mitochondrial disorder. The basal ganglia were not affected. More characteristic chronic findings of T2 prolongation and volume loss were later seen in our patient. The child improved with biotin and thiamine supplementation, a well-known feature of the condition. It is important for the radiologist and treating team to be aware of this variant and pursue further investigations to avoid delay in care and potential fatality.

Biotin-thiamine responsive basal ganglia disease (BTRBGD) is an autosomal recessive neurometabolic disorder with poor genotype-phenotype correlation, caused by mutations in the SLC19A3 gene on chromosome 2q36.6. The disease is characterized by three stages: stage 1 is a sub-acute encephalopathy often triggered by febrile illness; stage 2 is an acute encephalopathy with seizures, loss of motor function, developmental regression, dystonia, external ophthalmoplegia, dysphagia, and dysarthria; stage 3 is represented by chronic or slowly progressive encephalopathy. Clinical and biochemical findings, as well as the magnetic resonance imaging (MRI) pattern, resemble those of Leigh's syndrome, so that BTRBGD can be misdiagnosed as a mitochondrial encephalopathy.Here we report the clinical and radiological phenotypes of two siblings diagnosed with BTRBGD in which a novel SLC19A3 mutation (NM_025243.3: c.548C > T; p.Ala183Val) was found by whole exome sequencing (WES) of the family members.

Brain imaging is central to the diagnosis of infantile encephalitic beriberi. Because cranial sonography findings have not been described in infantile encephalitic beriberi, our aim was to investigate its role in the diagnosis of this condition. We performed a retrospective review of head sonography of infants (admitted between November 1, 2014, and March 31, 2015) who presented with encephalopathy. Cranial ultrasonography scans were studied for the alteration of echogenicity of the basal ganglia. Of the 145 consecutive infants who presented with encephalopathy, 58 had thiamine-responsive encephalopathy (infantile encephalitic beriberi) and 87 had encephalopathy due to other causes. Forty-eight of 145 infants with encephalopathy showed hyperechoic basal ganglia. A hyperechoic appearance of the basal ganglia on cranial ultrasonography was found to have a sensitivity of 71% (41/58) and a specificity of 92% (80/87) in diagnosing infantile encephalitic beriberi. The sensitivity of cranial sonography increased with age. It was a maximum of 93% (14/15) in the 5 months and older age group. Specificity was a maximum of 100% (18/18) in infants older than 5 months of age. Sensitivity was maximum in Wernicke encephalopathy at 90% (18/20) and least in the acidotic form at 43% (10/23). Follow-up showed gradual normalization of the hyperechoic appearance of the basal ganglia during 8 weeks in 26/41 (63%), with mild atrophy of the basal ganglia in 6/41 (15%) Hyperechogenicity of the basal ganglia on cranial ultrasonography is a sensitive finding for the diagnosis of infantile encephalitic beriberi in infants who present with Wernicke encephalopathy.