Cerebral blood flow and oxygen metabolism in progressive dementia associated with amyotrophic lateral sclerosis.

We examined regional cerebral blood flow (rCBF) and oxygen metabolism (rCMRO2) in 4 patients with progressive dementia associated with amyotrophic lateral sclerosis (ALS), in 9 patients with classical ALS without dementia, and in 13 normal controls, using positron emission tomography with oxygen-15 gas and oxygen-15 labeled carbon dioxide. The mean rCBF and rCMRO2 in the anterior cerebral hemispheres decreased significantly in patients with progressive dementia with ALS, compared to those in controls. Patients with only ALS showed very mild reductions of rCBF and rCMRO2 which were not statistically significant. These data suggest that hypoperfusion and oxygen hypometabolism in the anterior cerebral hemispheres have an etiological relationship to deterioration of intellect in patients with progressive dementia with ALS. A significant reduction in the mean rCBF was also found in the cerebellar hemispheres in progressive dementia with ALS, while a reduction of mean rCMRO2 was not significant. Remote effects analogous to crossed cerebellar diaschisis occurring bilaterally were assumed to explain the cerebellar hypoperfusion.