Biotinidase deficiency: a rare cause of laryngeal stridor

Laryngeal stridor in children caused by reversible metabolic disease

We report a case of a boy in his middle childhood who presented with inspiratory stridor and lactic acidosis and was subsequently diagnosed with partial biotinidase deficiency. Fibreoptic laryngoscope showed paradoxical vocal fold mobility.Partial biotidinase deficiency is an inherited disorder in which the body is unable to recycle the vitamin biotin. It may result in clinical consequences and can be easily treated with biotin but need a high index of suspicion to diagnose. The main symptoms include ataxia, seizures, hypotonia, psychomotor retardation, alopecia, skin rash, progressive deafness, optic atrophy and life-threatening episodes of metabolic acidosis. Laryngeal stridor is an uncommon presentation, but it is reversible in case of biotinidase deficiency. Invasive procedure like tracheostomy has not been shown to enhance outcomes.

Ohtahara syndrome with biotinidase deficiency

Ohtahara syndrome is a rare epileptic encephalopathy in infants; the underlying etiology is generally thought to be structural brain malformations. The authors present a rare case of this type of epileptic encephalopathy in which a treatable metabolic condition such as biotinidase deficiency was suspected and diagnosed, and early institution of appropriate therapy led to a good clinical outcome.

Biotinidase deficiency: a reversible metabolic encephalopathy. Neuroimaging and MR spectroscopic findings in a series of four patients

BACKGROUND

Biotinidase deficiency is a metabolic disorder characterized by inability to recycle biotin with resultant delayed myelination. Clinical findings include seizures, ataxia, alopecia and dermatitis with atypical findings of myoclonic jerks, neuropathy and spastic paraparesis. Neuroradiological findings include cerebral atrophy, encephalopathy and widened extracerebral CSF spaces. Many of the clinical and neuroradiological features are reversible except sensorineural hearing loss and optic atrophy.

OBJECTIVE

To understand and describe the neuroimaging and spectroscopic findings of biotinidase deficiency.

MATERIALS AND METHODS

We evaluated the spectrum of neuroimaging and spectroscopic findings in four patients with biotinidase deficiency with follow-up studies in three patients.

RESULTS

The imaging findings were encephalopathy, low cerebral volume, ventriculomegaly and widened extracerebral CSF spaces. Uncommon findings were caudate involvement, parieto-occipital cortical abnormalities and one patient with restricted diffusion. Two patients had subdural effusions, which is uncommon in biotinidase deficiency. 1H-MR spectroscopy revealed elevated lactate, reversal of the choline/creatine ratio and decreased NAA peaks. Follow-up studies revealed complete reversal of imaging findings in two patients.

CONCLUSION

Biotinidase deficiency is a reversible metabolic encephalopathy. This study highlights the importance of early and prompt cliniconeuroradiological diagnosis of biotinidase deficiency as it has an extremely good clinical outcome if treatment is initiated from early infancy.

Biotinidase deficiency: the importance of adequate follow-up for an inconclusive newborn screening result

Biotinidase deficiency is an inherited metabolic disorder characterized by inability to recycle protein-bound biotin. It usually presents with ataxia and seizures, though atypical presentations have also been described. We report a 15-month-old boy with profound biotinidase deficiency who presented with laryngeal stridor and subsequently developed severe ataxia and lactic acidosis. Subsequently, it was discovered that the patient's newborn screening test for biotinidase activity had been inconclusive, but confirmatory testing had not been done. Brain magnetic resonance imaging showed multiple white matter non-enhancing T2 hyperintensities, which largely resolved following 6 months of biotin therapy; however, there was residual deafness and mental retardation.

CONCLUSION

An argument is made for universal newborn screening in biotinidase deficiency and improved mechanisms for follow-up of positive screens, because delay in diagnosis results in irreversible morbidity, newborn screening is cost effective, and early therapy prevents the neurologic sequelae.