Increased brain glucose utilization in Salla disease (free sialic acid storage disorder).

Salla disease is an autosomal recessive lysosomal free sialic acid storage disorder characterized by psychomotor retardation and ataxia. MRI studies have revealed evidence of dysmyelination, but the biological mechanism of the brain dysfunction is unknown.

METHODS

Nine patients with Salla disease (age 2.5 mo-42 y) presenting the disease in varying degrees of severity were studied by PET using 2-fluoro-2-deoxy-D-glucose (FDG) as a tracer. Local cerebral metabolic rates for glucose (LCMRGlc) in individual brain regions were compared with controls.

RESULTS

The FDG PET results showed significantly increased LCMRGlc values in the frontal and sensorimotor cortex and especially in the basal ganglia of the patients. Cerebellar hypometabolism was present in all seven patients with marked ataxia, whereas the less severely affected patients without obvious ataxia had normal or even high glucose uptake in the cerebellum.

CONCLUSIONS

The increased cerebral glucose utilization is a constant finding in Salla disease and may reflect the basic defect of the sialic acid metabolism in this disorder. The FDG PET findings in the cerebellum suggest a correlation between glucose uptake and the severity of the clinical symptoms.