Neurophysiological characteristics in argininemia: a case report

Argininemia is a rare inherited disorder characterized by progressive spastic paraplegia, leading by mutation of the ARG1 gene. Liver transplantation (LT) had been reported to prevent symptoms progression, while its pathophysiology is still unclear. A 13-year-old male patient with argininemia for progressive neurological impairment was admitted to our center. Plasma amino acid screening showed a high concentration of arginine, and gene sequencing showed heterozygous mutation of the ARG1 gene. Spastic Paraplegia Rating Scale (SPRS), motor evoked potentials (MEPs), somatosensory evoked potentials (SEPs), F-wave, electromyography, nerve conduction velocity (NCV), and brain MRI were used to evaluate the patient. Herein, we describe the clinical characteristics of this patient, attempting a correlation between clinical, neurophysiological, and neuroimaging data in argininemia. Pyramidal tract dysfunction of lower limbs affected him, while only MEPs showed abnormalities among all neurophysiological evaluations, and mild cerebellum atrophy was observed. He responded poorly to traditional treatment such as a protein restriction diet and sodium benzoate. The symptoms of speech disorder, irritability, and dyskinesia were gradually deteriorating, so living-donor LT (LDLT) was done to prevent the progression. The symptoms improved significantly six months after LT, and the spasticity severity score decreased 50%. The findings suggest that LDLT is effective to argininemia, and the phenotypical similarities to other disorders that affect the urea cycle (HHH syndrome and pyrroline-5-carboxylate synthetase deficiency) suggest a common mechanism may contribute to maintaining the integrity of the corticospinal tract.