Maple syrup urine disease (MSUD): a case with long-term follow-up after liver transplantation

Maple syrup urine disease (MSUD) is a rare hereditary metabolic condition where the body is unable to breakdown amino acids causing toxic buildup. Acute and long-term management of MSUD involves a restricted diet and regular monitoring of amino acid levels; however, more recently liver transplants have been shown to be successful in treating this condition. Even with successful management of MSUD there is evidence from pediatric cases that shows a distinct pattern of neurocognitive deficits associated with this condition, including impaired nonverbal skills and psychomotor functioning with relatively intact verbal abilities. In the present paper, we report an adult case of MSUD with associated neurocognitive deficits and functional limitations following liver transplantation. Neuroimaging revealed no structural abnormalities, while the results from the neuropsychological evaluation showed impairment in visual-spatial processing, attention, executive functioning, and psychomotor abilities, with relative strengths in verbal skills. The patient also showed reduced adaptive functioning and mild anxiety. This case demonstrates neurocognitive deficiencies within the context of normal magnetic resonance imaging. The possible underlying mechanism of this neuropsychological profile is discussed in relation to other neurodevelopmental models.