Patterson, Marc C.

Seizures are often the first manifestation of central nervous system dysfunction and are common in many inborn errors of metabolism, especially in neonates, infants, and children. A high index of suspicion is required to diagnose inborn errors of metabolism as the cause of seizures. It is also important to recognize these metabolic disorders early, as specific disease-modifying treatments are available for some with favorable long-term outcomes. This review discusses the classification of metabolic disorders as a cause of seizures based on pathogenesis and age and proposes a tiered approach for cost-effective diagnosis of metabolic disorders.

Abnormal copper metabolism has been linked with neurological disorders, such as Wilson and Menkes disease. Another disorder causing symptoms similar to copper metabolism disorder is Niemann-Pick type C. However, a definite pathophysiological connection between Niemann-Pick type C and copper metabolism disorders has never been established. The authors present an adolescent with an unusual presentation of copper deficiency—dysarthria, ataxia, and vertical gaze paresis, without significant cognitive degeneration or pathological magnetic resonance imaging (MRI). The patient was found to carry 2 mutations in the NPC1 gene. A possible link, explaining how copper deficiency might induce the Niemann-Pick phenotype might involve overproduction of cholesterol and inhibition of acid sphingomyelinase. We suggest that copper metabolism disorders be included in the differential diagnosis for ataxia and dysarthria, even in cases with unusual presentations. Moreover, should the connection between copper and Niemann-Pick be validated, screening for copper metabolism disorders may be advisable in Niemann-Pick type C patients and vice-versa.

Niemann-Pick disease type C is a rare, genetic disease associated with impaired intracellular lipid trafficking and progressive neurological symptoms. Miglustat slowed disease progression in a 12-month randomized trial in juveniles and adults with Niemann-Pick disease type C, and in a parallel, noncontrolled study in affected children. Here, the authors report the open-label extension to the pediatric study. Patients aged 4 to 12 years received open-label miglustat (dose adjusted for body surface area) for an initial 12 months, during a further 12-month extension, and a long-term, continued extension phase. Efficacy assessments included horizontal saccadic eye movement, swallowing, and ambulation. Ten children completed 24 months’ treatment. Horizontal saccadic eye movement, ambulation, and swallowing were stabilized at 24 months. Analysis of key parameters of disease progression showed disease stability in 8 of 10 patients (80%). Miglustat stabilized neurological disease progression in pediatric patients with Niemann-Pick disease type C, with comparable safety and tolerability to that observed in adults and juveniles.