J. Inher. Metab. Dis. 19 (1996) 65-75 © SSIEM and KluwerAcademicPublishers.Printed in the Netherlands Clinical polymorphism of cystinosis encephalopathy. Results of treatment with cysteamine M. BROYER 1., M. J.TI~TE 1 , G. GUEST1, J. P. BERTHt~Lt~Mt~ 2, E LABROUSSE 3 and M. POISSON 4 1Department of Pediatric Nephrotogy and INSERM U 423, H6pital Necker-Enfants Malades, Paris; 2Centre Hdliomarin de Roscoff, Roscoff; 3Department of Pathology, Centre Hospitalier, Limoges; 4Department of Neurology, H@ital de la Pitid-Salp~tridre, Paris, France *Correspondence: Service de Ndphrologie pddiatrique, H6pital Necker-EnJhnts Malades, 149 rue de Sdvres, 75743 Paris, France MS received 23.5.95 Accepted16.8.95 Summary: Of the 26 cystinotic patients over 19 years of age followed in our institution, 7 developed CNS complications at a mean age of 23 years. Two forms were observed. The first, associating cerebellar and pyramidal signs, mental deterioration and finally pseudo-bulbar palsy, may be called cystinosis encephalopathy. The other form resembled a stroke-like episode with coma and hemiplegia or milder symptoms. Hydrocephalus was rare and not associated with clinical symptoms in this series. Cysteamine was administered for longer than 6 months to 4 of the patients with encephalopathy. Two had an almost complete disapp6arance of their symptoms including the gross abnormalities of MR imaging in one; one improved partially and remained stable, and one continued to deteriorate but was suspected of non- compliance. These results suggest that cysteamine may be an effective treatment of cystinosis encephalopathy and encourage prescription of this drug in cystinosis in order to prevent this complication Cystinosis (McKusick 219800) is an inheritable metabolic disorder related to intra- lysosomal cystine accumulation as a consequence of defective transport of cystine across the lysosomal membrane. The disease is characterized by the appearance of a severe renal tubular Fanconi syndrome in the first months of life and later by progressive renal failure reaching end stage between the ages of 6 and 14 years. The possibility of limiting and/or postponing this evolution by treatment with oral cysteamine has been shown (Gahl et al 1987; Markello et al 1993). Cystine storage occurs in most tissues and, since renal trans- plantation now allows these patients to survive, it was predictable that other organs could become involved by the disease. In fact, functional alteration of the endocrine pancreas and diabetes (Bakchine et al 1984), hypothyroidism (Chanet al 1970; Lucky et al 1977), 65