Objective: To demonstrate possible disturbances in pedinculopontine nucleus (PPN) and its connections in freezing of gait (FOG) by DTI in conjunction with the cognitive profile.

Background: FOG is an episodic gait pattern that is common in advanced PD and other atypical Parkinsonian syndromes. Mechanisms underlying FOG have been tried to be explained on the basis of dysfunctions in the basal gaglia-thalamo-cortical circuit and fronto-parietal networks. However, results of recent studies revealed disturbances centered in PPN and its connections.

Methods: We included 31 patients with PD [18 FOG(+), 13 FOG(-)] and 12 healthy subjects as well as a group of patients with progressive supranuclear paralysis (PSP) [6 FOG(+), 5 FOG(-)]. We investigated FA and MD values in a wide range of regions of interest including PPN and 23 other cerebral and cerebellar areas which have previously been demonstrated to be in connectivity with PPN. To determine the specific cognitive parameters associated with FOG, deliberate cognitive evaluation of all the individuals were performed.

Results: In cognitive profiling, lower performance for visuospatial functions were demonstrated in FOG(+) individuals with both PD and PSP. We have found disturbances of values in bilateral superior frontal gyrus(SFG)-FA/MD, fastigial nucleus (FN)-FA, left pre-supplementary motor area (pre-SMA)-FA in FOG(+) PD group relative to FOG(-) PD group. Correlation analysis revealed negative correlation of FOG scores with left SFG-FA and left pre-SMA-FA values. The analysis of the PSP group demonstrated disturbance in left pre-SMA values in FOG(+) PSP group likewise, while negative correlations were determined between right subthalamic nucleus (STN), left PPN values and FOG scores.

Conclusions: These results revealed that disturbances in visuospatial abilities may be the critical step for occurrence of FOG. Together with the results of DTI analysis, it might be suggested that impairment in the connectivity of disturbed frontal areas with disordered basal ganglia, may be the key factor for development of FOG in PD group, whereas left PPN may play a more prominent role in the process of FOG in PSP. Moreover, our results pointed out the previously mentioned right STN and for the first time FN as crucial areas in development of FOG, hence suggest these regions as potential target nuclei for future treatment based studies of pathogenesis.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/comparative-analysis-of-freezing-of-gait-in-distinct-parkinsonism-types-by-diffusion-tensor-imagining-and-cognitive-profiles/