Late-onset drug-resistant epilepsy in pyridoxamine 5'-phosphate oxidase deficiency: a case report.

Abstract

Pyridoxamine 5'-phosphate oxidase deficiency is a rare inborn error of vitamin B6 metabolism that presents with drug-resistant epileptic seizures. However, the condition is responsive to supplementation with the active vitamin B6 metabolite pyridoxal 5'-phosphate and, in some cases, pyridoxine. In this case report, a 10-year-old Iranian male of Fars ethnicity came to a regional hospital in Tehran, Iran with a chief complaint of tic-like movement. He had a history of unintentional, repetitive, and stereotypic movements of both arms since the age of 4years. The physical examination depicted facial dimorphism. During admission, the patient experienced habitual hypermotor seizures and generalized tonic-clonic seizures. Ictal electroencephalography demonstrated a generalized background attenuation and bursts of generalized, predominantly left-sided, biphasic spike-wave complexes. Whole-genome sequencing revealed a pyridoxamine 5'-phosphate oxidase deficiency as the underlying cause of the drug-resistant seizures, resulting in a low serum level of pyridoxal 5'-phosphate. The patient underwent pyridoxine supplementation therapy, which ultimately resolved his seizures. At 6months, he was seizure free. Physicians ought to be aware of manifestations of vitamin B6 deficiency such as mimicking tic and consider it in the differential for drug-resistant epilepsy.