Motor Improvement-Related Regional Cerebral Blood Flow Changes in Parkinson's Disease in Response to Antiparkinsonian Drugs

Little is known about the relationship between regional cerebral blood flow (rCBF) change and clinical improvement in patients with Parkinson's disease (PD). Single-photon emission computed tomography (SPECT) measurement of cerebral blood flow allows evaluation of temporal changes in brain function, and using SPECT, we aimed to identify motor improvement-related rCBF changes in response to the administration of antiparkinsonian drugs. Thirty PD patients (16 without dementia; 14 with dementia) were scanned with technetium-99m labeled ethyl cysteinate dimer SPECT and were rated with the Movement Disorder Society-Unified Parkinson's Disease Rating Scale part III, both before and after a single administration of antiparkinsonian drugs. The SPECT data were processed using Statistical Parametric Mapping 2, the easy Z-score Imaging System, and voxel-based Stereotactic Extraction Estimation. The rCBF responses in the deep brain structures after administration of antiparkinsonian drugs tended to be larger than those in cortical areas. Among these deep brain structures, the rCBF increases in the substantia nigra (SN), lateral geniculate (LG) body, and medial geniculate (MG) body correlated with drug efficacy (p < 0.05, respectively). A subgroup analysis revealed that the motor improvement-related rCBF change in the MG was statistically significant, irrespective of cognitive function, but the significant changes in the LG and SN were not found in subjects with dementia. In conclusion, our SPECT study clearly exhibited drug-driven rCBF changes in PD patients, and we newly identified motor improvement-related rCBF changes in the LG and MG. These results suggest that rCBF changes in these regions could be considered as candidates for clinical indicators for objective evaluation of disease progression. Furthermore, functional studies focusing on the LG and MG, especially in relation to therapies using audio-visual stimuli, may bring some new clues to explain the pathophysiology of PD.