Measurement of regional cerebral blood flow (rCBF) in 30 patients with Parkinson''s disease using single-photon emission computed tomography and 123I-IMP demonstrated that hypoperfusion was relatively severer in the parietal cortex than other cortices before and after a 1-year follow-up period. The decline in the scores of the Mini-Mental State Examination was significantly correlated with the decrease in rCBF in the parietal cortex during the follow-up period. Our flndings suggest that the parietal cortex is involved in the cognitive impairment in patients with Parkinson''s disease.

Hemispheric dominance for motor control in the human brain is still unclear. Here we propose asymmetric sensorimotor integration during human hand movements. We investigated the dexterity of hand movements and related sensory functions in four right-handed patients with cerebrovascular lesions in the postcentral gyrus. To clarify the distributions of cortical damage, semiquantitative analysis of regional cerebral blood flow (rCBF) was performed using single photon emission computed tomography (SPECT), and a three-dimensional surface display was generated from SPECT. Scores on motor and sensory tasks and rCBF values in the patients were compared with those in control subjects. All patients presented with asymmetric clumsiness of complex finger movements, in association with impairments of combined sensations such as stereognosis. These findings were indicative of a disorder of sensory information processing necessary to guide the movements. Two patients with left hemispheric damage showed bilateral clumsy hands, predominating on the right side, while the other two patients with right hemispheric damage showed only a left clumsy hand. In agreement with asymmetric clumsiness, measurement of rCBF along with a three-dimensional surface display revealed cortical hypoperfused areas, mainly in the perirolandic cortices, comprising the primary motor and somatosensory cortices. Perirolandic cortical hypoperfusion was bilateral in the two patients with bilateral clumsy hands, but only on the right side in the other two patients with left clumsy hands. These results suggest a dominant role of the left somatosensory cortex in sensorimotor integration for complex finger movements of humans.

We reconstructed three-dimensional (3D) surface images from data from single-photon emission computed tomography (SPECT) with N-isopropyl-p[¹²³I]-iodoamphetamine (¹²³I-IMP) in 29 patients with Parkinson''s disease, 16 patients with Alzheimer''s disease and 11 normal control subjects. In patients with nondementing Parkinson''s disease, perfusion defects were frequently found in the parietal cortical region at a threshold value of 65%. In demented Parkinson''s disease patients, perfusion defects were frequently noted at threshold of 45–65 %, and were more marked in the bilateral temporal and parietal cortices. In Alzheimer''s disease, perfusion defects were similar to those found in dementing Parkinson''s disease. These results suggest that dementia in Parkinson''s disease is related to the perfusion reduction of the temporoparietal cortex, and may support the view that Parkinson''s disease and Alzheimer''s disease overlap in some patients. A 3D display of an ¹²³I-IMP brain tomogram may be useful for detecting cortical lesions in patients with dementia or cognitive impairment.

We reconstructed three-dimensional (3D) surface images from single-photon emission computed tomography (SPECT) data using N-isopropyl-p[123I]-iodoamphetamine (123I-IMP) in 27 patients with Parkinson's disease and 11 normal control subjects. The 3D reconstruction was performed using distance-shaded methods at threshold levels with an interval of 5% from 45-80%. Any area of decreased perfusion at each threshold level was visualised as a defect area by the algorithm. In nondemented patients with Parkinson's disease, perfusion defects were frequently found in the parietal cortex at a threshold value of 65%. In demented patients, perfusion defects were frequently seen at thresholds of 45-65%, and were more marked in the temporal and parietal cortex bilaterally. This suggests that dementia in Parkinson's disease is related to a reduction of perfusion in the temporoparietal cortex.

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