Objective: Freezing of gait is a common complaint in patients with Parkinson’s disease (PD). However, the neural bases of freezing of gait in PD remain uncertain. Existing studies on PD patients with freezing of gait (PD-FOG+) have reported damage of the corpus callosum, the largest commissural bundle of the brain. Thus, in this study we explored homotopic connectivity to investigate FOG-related interehemispheric alterations.

Background: Freezing of gait (FOG), which affects approximately 50% of people with Parkinson disease (PD), is a disabling phenomenon that seriously affects the quality of life of PD patients. [1]. Early studies had shown that impaired control of rhythmicity, bilateral incoordination, and gait asymmetry were important aspects of freezing. Similarly, some studies had reported that the poor coordination between the legs or gait cycle disorders were related to FOG. Recently, several studies have found damage of the corpus callosum in PD patients with FOG using structural and functional connectivity. It is well known that the corpus callosum (CC) is the main collection of white matter bundles connecting both hemispheres so that both sides of the body can be coordinated. Its structural damage may affect the functional coordination between the cerebral hemispheres. Thus, it is reasonable to expect that the deficits of hemispheric interactions play a key role in the pathophysiology of FOG in PD. Therefore, it would be meaningful to examine the inter-hemispheric coordination in PD patients with FOG.

Methods: A total of 21 PD-FOG+ patients, 33 PD patients without freezing of gait (PD-FOG-), and 24 matched healthy controls were recruited. All PD patients were evaluated via the FOG questionnaire (FOGQ) and all subjects had a resting state functional magnetic resonance imaging (rs-fMRI) scan. The pattern of the homotopic connectivity was measured with the voxel-mirrored homotopic connectivity (VMHC) approach.

Results: The PD-FOG+ patients showed decreased VMHC values in the inferior parietal lobe (IPL) compared to both PD-FOG- patients and healthy controls. In PD-FOG+ patients, the mean VMHC values in the IPL were negatively correlated with the FOGQ scores. Receiver operating characteristic curves analyses revealed that the VMHC in the IPL had discriminatory function distinguishing PD-FOG+ patients from PD-FOG- patients or healthy controls.

Conclusions: Decreased VMHC values of PD-FOG+ patients relative to PD-FOG- and healthy controls in IPL maybe a unique feature for PD-FOG+ and it may have the ability to separate PD-FOG+ patients from PD-FOG- and healthy controls.

References: [1] M. Macht, Y. Kaussner, J.C. Moller, K. Stiasny-Kolster, K.M. Eggert, H.P. Kruger, H. Ellgring, Predictors of freezing in Parkinson’s disease: a survey of 6,620 patients, Mov Disord 22(7) (2007) 953-956.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/decreased-interhemispheric-homotopic-connectivity-in-parkinsons-disease-patients-with-freezing-of-gait-a-resting-state-fmri-study/