Fourteen patients with cystinosis, eight males and six females ranging in age from 13 to 24 years (mean 18.1 years) were examined for neurological involvement at the National Institute of Neurologic and Communicative Disorders and Stroke, the National Institutes of Health Clinical Center, Bethesda, Maryland. Two patients had neurological symptoms, including bradykinesia, dementia and spasticity, and behavioral and cognitive disturbances; 12 patients had CT evidence of generalized cerebral atrophy; two had multifocal intracerebral mineralization on CT scan; two had abnormal electroencephalograms and only one patient was entirely normal. Patients with neurologic symptoms or markedly abnormal CT scans were older and had a longer interval between their initial renal transplantation and the examination at follow-up than those patients who were normal or who had only mild cerebral atrophy. The neurologic and neuropsychometric abnormalities correlated with the degree of roentgenographic abnormality. The patients with nervous system abnormalities were not distinguished by patterns of medication use or the relative severity of cystinosis. The differential diagnosis included other complications from renal failure, dialysis and immunosuppression. 
COMMENT. The central nervous system involvement in nephropathic cystinosis has not been implicated until recently. Survival into adulthood following renal dialysis and transplantation has drawn attention to the sequelae of long-standing cystinosis. Cystinosis is a rare autosomal recessive disorder of children and adults characterized biochemically by the intracellular accumulation of cystine crystals in the kidneys, bone marrow, and cornea as well as the reticuloendothelial system. With increasing longevity, involvement of other organs such as the thyroid, pancreas, and central nervous system has become apparent. Three different patterns of the disease are recognized depending on the degree of cystine accumulation: Infantile nephropathic form, intermediate or late onset adolescent form, and a benign adult form. The clinical manifestations of infantile cystinosis include recurrent episodes of dehydration, the Fanconi renal tubular syndrome, retarded growth, anemia, photophobia, retinopathy, and vitamin D resistant rickets. Long-term treatment with Cysteamine may delay or prevent the accumulation of cystine crystals in various organs and may alter the prognosis . Biopsy specimens of cerebral cortex and meninges have revealed cystine crystals in the walls of arachnoidal blood vessels and in the cytoplasm of cortical neurons, basal ganglia, thalamus, cerebellum and posterior pituitary. The relationship of these crystalline deposits to neurological abnormalities has not been determined.