Corpus callosum and cingulum tractography in Parkinson's disease.
BACKGROUND
In Parkinson's disease (PD) cell loss in the substantia nigra is known to result in motor symptoms; however widespread pathological changes occur and may be associated with non-motor symptoms such as cognitive impairment. Diffusion tensor imaging is a quantitative imaging method sensitive to the micro-structure of white matter tracts.


OBJECTIVE
To measure fractional anisotropy (FA) and mean diffusivity (MD) values in the corpus callosum and cingulum pathways, defined by diffusion tensor tractography, in patients with PD, PD with dementia (PDD) and controls and to determine if these measures correlate with Mini-Mental Status Examination (MMSE) scores in parkinsonian patients.


METHODS
Patients with PD (17 Males [M], 12 Females [F]), mild PDD (5 M, 1 F) and controls (8 M, 7 F) underwent cognitive testing and MRI scans. The corpus callosum was divided into four regions and the cingulum into two regions bilaterally to define tracts using the program DTIstudio (Johns Hopkins University) using the fiber assignment by continuous tracking algorithm. Volumetric MRI scans were used to measure white and gray matter volumes.


RESULTS
Groups did not differ in age or education. There were no overall FA or MD differences between groups in either the corpus callosum or cingulum pathways. In PD subjects the MMSE score correlated with MD within the corpus callosum. These findings were independent of age, sex and total white matter volume.


CONCLUSIONS
The data suggest that the corpus callosum or its cortical connections are associated with cognitive impairment in PD patients.
Glenrose Rehabilitation Hospital, Edmonton, Alberta, Canada.
Katie
K
Wiltshire
Luis
L
Concha
Myrlene
M
Gee
Thomas
T
Bouchard
Christian
C
Beaulieu
Richard
R
Camicioli
D000368:Aged; D003337:Corpus Callosum / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006179:Gyrus Cinguli / Q000473:pathology*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D008609:Mental Status Schedule; D010300:Parkinson Disease / Q000473:pathology*