EVIDENCE FOR A DOPAMINERGIC DEFICIT IN SPORADIC AMYOTROPHIC-LATERAL-SCLEROSIS ON POSITRON EMISSION SCANNING

Although rare, the chronic neurodegenerative disorders amyotrophic lat eral sclerosis (ALS) and idiopathic parkinsonism coexist to a greater degree than expected by chance. This suggests that patients with ALS m ay have subclinical lesions of the nigrostriatal dopaminergic pathway. To study this hypothesis, we did positron emission tomography with 6- fluorodopa on 16 patients with sporadic ALS and without extrapyramidal disease, and compared the results with age-matched controls. We found a significant progressive fall in 6-fluorodopa uptake with time since diagnosis, and reduced dopaminergic function in 3 patients with ALS o f long duration. This supports the hypothesis that ALS and IP may shar e pathogenesis and, perhaps, aetiology.