Objective: We investigated pedunculopontine nucleus (PPN) structural integrity in Parkinson disease (PD) patients with diffusion tensor imaging (DTI) and whether the DTI changes correlate with freezing of gait (FOG).

Background: FOG causes significant quality of life impairment in PD patients and does not respond well to dopaminergic treatment. The mechanism of FOG is not well established, but it is thought to be mediated by cholinergic dysfunction of the PPN, which is a critical locomotion center for gait and balance. Currently, there is no accurate imaging method to predict FOG in PD patients. We propose that using DTI, we can study the microstructural changes and structural dysconnectivity to and from the PPN to help predict FOG and other gait dysfunction parameters in PD patients.

Method: Thirteen PD patients with (PD-FOG+) and without FOG (PD-FOG-) were recruited from the University of Alberta Parkinson and Movement Disorders Program. FOG is defined by the score >1 of question 3 on the FOG questionnaire. All participants underwent DTI to quantify the structural connectivity of the PPN. DTI was performed at 3.0T using 60 directions of diffusion gradient. Midbrain images at the level of the superior cerebellar peduncle (SCP) decussation were analyzed by placing regions of interest (ROI) between SCP and medial lemniscus. Fractional anisotropy (FA) and mean diffusivity (MD) were calculated using ExploreDTI. Gait parameters were recorded on Zeno Walkway. We analyzed the differences of the FA and MD, as well as the gait parameters between the 2 study cohorts with the Student T-test. The correlations between FA and MD with behavioral gait measures, velocity, stride length, stride time, cadence were analyzed using regression models.

Results: The PD-FOG- group had faster gait velocity and longer stride length compared with the PD-FOG+ group (p<0.05).  There was no significant difference for cadence between the 2 groups. MD of the PPN was higher in the PD-FOG+ group (p<0.01), but it did not correlate with the behavioral gait measures.  No difference of the FA was seen between the 2 groups.

Conclusion: Structural dysconnectivity of the PPN can help assess PD patients with FOG in conjunction with other imaging tools, e.g. fMRI, SWI, and in association with gait analysis. These measures can guide clinical assessment and management options.

« Back to 2022 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/pedunculopontine-nucleus-structural-integrity-and-freezing-of-gait-in-parkinsons-disease-patients/