RESUMO
Biotinidase deficiency is a treatable cause of severe neurological disorders and skin disorders. Most symptomatic patients will have neurological, cutaneous manifestations and typical organic aciduria. Spinal cord involvement is a rare manifestation of this disease and is commonly unrecognized. We report a previously healthy boy who presented at the age of 28 months with recurrent ataxia and mild alopecia, and MRI evidence of spinal cord demyelination. Biotinidase deficiency was confirmed later. Supplementation with biotin resulted in disappearance of the symptoms and normalization of the MRI spinal cord changes. Biotinidase deficiency, as a treatable condition, should be considered in the differential diagnosis in any child who presents with neurological symptoms and spinal cord demyelination with or without alopecia