[Corticobasal degeneration: a combined clinical, PET and pathological study]

We report 2 cases of corticobasal degeneration (CBD) with reference to the clinical and pathological features and neuroimaging including MRI, positron emission tomography (PET) and single photon emission tomography (SPECT). Case 1 was a 66-year-old right-handed woman. Her spontaneity had been gradually impaired, and she showed a progressive course of naming difficulty, memory disturbance, and right unilateral spatial neglect in addition to the right hemi-parkinsonism and bilateral pyramidal tract signs. Cortical and subcortical atrophy was predominant in the left hemisphere on MRI. As compared with the right side, both cerebral blood flow (CBF) and oxygen metabolism (CMRO2) were decreased in the left hemisphere on the PET which was performed 4 years after onset. She showed further clinical deterioration, and exhibited a bilateral parkinsonism 6 years after the onset. The follow-up SPECT revealed diffusely bilateral hypoperfusion except for the basal ganglia and occipital lobes 6 years after the onset. Case 2 was a 56-year-old right-handed woman. She exhibited a progressive course of bilateral parkinsonism, hallucinations and vertical eye movements disturbance. She died of infection 42 months after the onset of the initial symptoms. Bilateral frontal atrophy was seen on X-ray CT and MRI. PET revealed a diffuse moderate decrease in CBF and CMRO2 particularly in the frontal cortex, central semiovale, paraventricular white matter and cingulate gyrus bilaterally. Pathological examination disclosed a mild frontal atrophy, and there was diffuse neuronal loss, gliosis, and achromasia in the cerebral cortices. There was moderate neuronal cell loss and gliosis in the thalamus, whereas the globus pallidus, striate and substantia nigra were severely affected. Neuronal inclusions termed corticobasal inclusions were present in the substantia nigra, nuclei raphes, and Meynert's nuclei, and none of these regions contained Pick's cell. PET and SPECT studies revealed an asymmetrical decrease in CBF and CMRO2 in the initial stage and diffuse bilateral decrease in the advanced stage in Case 1, whereas Case 2 showed a bilateral decrease in the late stage. This may indicate that the patterns of hypoperfusion and/or hypometabolism differs according to the clinical stages of CBD.