Biotinidase Deficiency Presenting as Recurrent Myelopathy in a 7-Year-Old Boy and a Review of the Literature

Novel imaging findings in two cases of biotinidase deficiency-a treatable metabolic disorder

“…This pattern of involvement is usually seen in older children (delayed onset) with biotinidase deficiency who are asymptomatic till adolescence just like the present case (Wolf et al 1998). All the previous reports have described diffuse cord involvement on MRI (Raha and Udani 2011). In our patient symmetric anterior, lateral and posterior column hyperintensities were seen on T2WI.…”

“…Brain imaging findings in biotinidase deficiency have been described in literature and include cerebral atrophy, ventriculomegaly, widened extracerebral spaces, subdural effusions, basal ganglia calcifications and T2 hyperintensities involving corona radiata, splenium of corpus callosum, posterior limbs of internal capsule, middle cerebellar peduncles, septum pellucidum, fornix, dorsal brainstem, optic tracts, optic chiasma, basal ganglia, medial thalamus, periaqueductal and parieto-occipital grey matter (Desai et al 2008;Wolf 1991;Raha and Udani 2011).…”

Biotinidase deficiency should be considered in individuals exhibiting myelopathy with or without and vision loss

“…Spinal cord imaging usually shows hypodensity, demyelination and/or edema of the spinal cord that may extend from the brainstem/medulla down the spine involving the cervical, thoracic or entire spinal cord, [10,13,19]. It is important that the location, bulbar, upper and/or lower extremities, or severity of the peripheral symptoms may correlate with the degree of involvement of the cord observed on imaging.…”

“…In fact, the following disorders were initially diagnosed in children and adolescents who were ultimately found to have profound biotinidase deficiency: acute inflammatory myelitis [20], multiple sclerosis [10,20], transverse myelitis [14,15,19], myasthenia gravis [14], Leigh syndrome [11,19], Leber hereditary optic atrophy [10], neuromyelitis optica [19,20], brainstem encephalitis [20] and Weinicke encephalopathy [11]. Because those individuals ultimately found to have biotinidase deficiency did not improve with immunological therapy, it is possible that some of the individuals reported in the literature who were diagnosed with a myelitis or multiple sclerosis, did not improve with immunological therapy, and continued to exhibit myelopathic symptoms or even deteriorated further, could have actually had biotinidase deficiency.…”

“…Of the individuals who have had mutation analysis, all have had missense mutations with some residual enzymatic activity [10,13,19]. Of those who have had mutation analysis, none of those tested have had null mutations resulting in the complete absence of enzyme or enzyme activity.…”