Objective: To assess the integrity of the Superior Longitudinal Fascicle (SLF) and its relationship with the Anticipatory Postural Adjustments (APAs) of step initiation in people with Parkinson’s disease (PD) with (FOG) and without (nFOG) Freezing of Gait.

Background: Disorders of the SLF have been related to FOG pathophysiology. The SLF controls movements by being connected to brain areas that regulates motor preparation (APAs). The relationship of its integrity and APAs in FOG is not known.

Methods: Eleven FOG and eleven nFOG patients performed 30 trials of step initiation. Medio-lateral force under the support leg (APAs) was recorded. Diffusion images were acquired in a 3T MR scanner. Diffusion-weighted images analysis provided the fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (DA), and radial diffusivity (RD) of the parietal and temporal part of both SLF. Comparisons between groups were performed through a T-test and correlation between diffusion variables and APAs by Pearsons analysis. Statistical significance was set as p<0.05.

Results: Statistical analysis showed higher FA values for FOG (M = 0.39, SD = 0.04) compared to nFOG (M = 0.35, SD = 0.02) patients only for the left parietal SLF. The nFOG group presented increased APA (M = 0.25, SD = 0.03, normalized value) compared to FOG (M = 0.19, SD = 0.07). Main results also evidenced positive correlations between APA and AD, MD and FA for the left parietal SLF and negative correlations for the right temporal and parietal SLF in the nFOG group. Patients with FOG only presented positive correlations between FA and APA for the right temporal part of the SLF and no correlations for the remaining areas. Figure 1 shows the correlations between the diffusion variables and APA for the left parietal part of the SLF (significant correlations are marked by asterisks). Red lines, markers and values represent nFOG and black FOG groups.

Conclusions: The results suggest that the SLF is involved in FOG pathophysiology, given that mainly patients without FOG showed correlation of the size of the APA with the diffusion characteristics. Another important result is that FA of the left parietal part of the SLF is increased in FOG patients, which may be associated with compensatory mechanisms such as axonal plasticity and reduced branching of the pathway that includes the SMA.

« Back to 2016 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/integrity-of-the-superior-longitudinal-fascicle-and-its-relationship-with-anticipatory-postural-adjustments-in-people-with-parkinsons-disease-and-freezing-of-gait/