Objective:Our objective was to determine whether changes in the non-dopaminergic pedunculopontine nucleus (PPN) region could be shown in Parkinson's disease (PD) with MRI, a non-invasive measurement. We hypothesize that these changes may be associated with development of dopamine (DA) non-responsive features.Background:There's increasing evidence that PD is more complex than a simple DA responsive motor disorder, particularly in advanced stages. Balance impairment and gait disturbances, such as freezing, are often unresponsive to DA replacement therapy. The PPN is involved in locomotion. Rostral PPN neurons are important in the initiation of programmed movements while other PPN neurons provide feedback to basal ganglia and thalamus. A significant loss of PPN neurons is evident in PD from autopsy study. PPN stimulation has been shown to improve gait difficulties.Design/Methods:Optimally treated PD patients with gait/balance changes from the Movement Disorders Program at University of Alberta were enrolled (n=21) in this study. Healthy age-matched controls (n=9) were also recruited. Diffusion tensor imaging was performed at 1.5T using 30 directions of diffusion gradient. Midbrain images at the level of superior cerebellar peduncle (SCP) decussation were analyzed by placing regions of interest (2.5-3mm diameter) between medial lemniscus and SCP. Similar regions were placed on corticospinal tract (CST) at the same level for comparison. Fractional anisotropy (FA) and mean diffusivity (MD) were calculated using ExploreDTI. Differences between the 2 groups were analyzed using Student's t-test.Results:Patients with PD had decreased FA (p<0.05) in the PPN region compared to controls. There was no difference in MD, nor any difference in either measurement in CST between the 2 groups.Conclusion:These data support the presence of neuropathological changes in the PPN in PD. Future studies are required to elucidate changes in PPN connections with other structures and the relationship with balance/gait difficulties in PD.
Disclosure: Dr. Ba has nothing to disclose. Dr. Wieler has nothing to disclose. Dr. Gee has nothing to disclose. Dr. Martin has nothing to disclose.
Original Article: http://www.neurology.org/cgi/content/short/82/10_Supplement/P2.002?rss=1
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