Biotin-Responsive Basal Ganglia Disease (BBGD)

Basal ganglia are neurons deep within the brain which control movement. A number of conditions, including inborn errors of metabolism, can cause lesions involving the basal ganglia and result in neurological disorders that affect movement.⁵⁹

One such movement disorder is biotin-responsive basal ganglia disease (BBGD), considered to be related to an underlying energy metabolism condition. BBGD is a recessive hereditary condition that typically presents itself in childhood or adolescence but can initially present symptoms in adults as well. While it was previously thought to only occur in Saudi, Syrian, and Yemeni patients born of related parents, it was recently discovered in two adults of Portuguese ancestry who had recurrent neurological problems.^59-62

Symptoms include:

• Brain lesions - typically in the basal ganglia structures (putamen and caudate).⁶⁰
• Cogwheel rigidity - muscle stiffness that causes jerky movements.⁶⁰
• Dystonia - muscle contractions that create twisting and abnormal postures.^59-60
• Epilepsy - brain disorder characterized by recurrent seizures.⁵⁹
• Oculogyric crisis - spasmodic eyeball movements.⁵⁹
• Quadriparesis - weakness in all four limbs.⁶⁰
• Sub-acute encephalopathy - neurological impairments that develop over weeks to months (e.g., confusion, speech impairment, and difficulty swallowing), typically preceded by headaches, vomiting, or diarrhea.^59-61

Without treatment BBGD can be fatal, but high-dose biotin treatment prevents disease progression and symptoms disappear. The unexpected finding of BBGD in adults outside the geographic area it was thought to be confined to has prompted experts to recommend high-dose biotin (with another B vitamin, thiamine) therapy in any patient with unexplained encephalopathy with lesions in the putamen and caudate.^{60, 62}