<p>Dopaminergic pathway and primary visual cortex are involved in the freezing of gait in Parkinson’s disease: a PET-CT study</p>

Abstract

Background: Freezing of gait (FOG) could be partly alleviated by dopaminergic drugs but the mechanism still needs to be elucidated. The purpose of this study is to explore the mechanisms of FOG by vesicular monoamine transporter VMAT2 distribution with the 18 F-AV133 tracer and 18-fludeoxyglucose positron emission tomography–computed tomography ( 18 F-FDG PET-CT). Methods: Clinical material and PET-CT data were collected from 20 patients with FOG and 147 patients without FOG from November 1, 2017 to October 31, 2018. Brain scans of all participants were acquired over an approximately 20-min period, 120 min after injection of approximately 250 MBq 18 F-AV133. The mean uptake ratios of different regions were identified by NeuroQ software of 18 F-FDG PET-CT. Data analysis included variance, chi-square analysis, covariance analysis, and logistic regression. Results: Our data showed that patients with FOG were provided with greater doses of dopaminergic drugs ( p <0.05). The frequency of FOG was 11.98% and increased as Parkinson’s disease progressed. FOG was more common in the elderly and strongly associated with the duration. Cognitive impairments were obvious, assessed by Mini-Mental State Examination and Montreal Cognitive Assessment ( p <0.05). The VMAT2 distribution with 18 F-AV133 was decreased significantly in the caudate nucleus and lentiform nucleus while the metabolism of these areas was elevated, determined by 18 F-FDG PET-CT ( p <0.05). The metabolism of the primary visual cortex decreased obviously in patients with FOG compared with those without FOG ( p <0.05). Conclusion: FOG mainly occurred in the advanced stage, and was strongly associated with the duration and larger dose of dopaminergic drugs. The dopamine level of the nigrostriatal system decreased significantly and the uptake ratios of the primary visual cortex dropped obviously in the FOG group compared with the non-FOG group. Our study suggests that both the dopaminergic pathway and the primary visual cortex are involved in the pathogenesis of FOG.

Brain network topology and future development of freezing of gait in Parkinson’s disease: a longitudinal study

“…Moreover, previous neuroimaging experiments have also implicated the visual cortex may be involved in the occurrence of FOG. Besides impaired functional connectivity in the visual cortex [8,11], one recent neurometabolic study using glucose positron emission tomography (PET) further supported that PD patients with FOG had lower metabolic activity in the visual cortex compared with those without FOG [41]. In particular, one virtual reality task-based fMRI study demonstrated that PD patients with FOG had increased visual cortex activation during turning, implicating that PD patients with FOG were over-reliant on visual information [42].…”

Altered Degree Centrality of Brain Networks in Parkinson's Disease With Freezing of Gait: A Resting-State Functional MRI Study

“…The typical FOG symptom usually lasts for a few seconds, but occasionally can last for 30 s or more ( 6 ). Unlike other cardinal symptoms, FOG cannot be satisfactorily managed by dopaminergic medication or deep brain stimulation ( 7 , 8 ).…”

Alterations of structure and functional connectivity of visual brain network in patients with freezing of gait in Parkinson’s disease

“…Converging evidence has supported that resting state functional connectivity within the visual network decreased in PD-FOG patients (Tessitore et al, 2012;Canu et al, 2015). Moreover, Zhou et al (2019) observed significant decrease of the metabolism of the primary visual cortex using PET-CT in PD-FOG group compared with PD-NFOG (Zhou et al, 2019). It has been postulated that hypoactivation in visual brain area might underlie the deficits of visual network related to gait disturbances.…”