Neuroimaging advances in Parkinson's disease with freezing of gait: A systematic review

Abstract

Freezing of gait (FOG) is a paroxysmal gait disorder that often occurs at advanced stages of Parkinson's disease (PD). FOG consists of abrupt walking interruption and severe difficulty in locomotion with an increased risk of falling. Pathophysiological mechanisms underpinning FOG in PD are still unclear. However, advanced MRI and nuclear medicine studies have gained relevant insights into the pathophysiology of FOG in PD. Neuroimaging studies have demonstrated structural and functional abnormalities in a number of cortical and subcortical brain regions in PD patients with FOG. In this paper, we systematically review existing neuroimaging literature on the structural and functional brain changes described in PD patients with FOG, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We evaluate previous studies using various MRI techniques to estimate grey matter loss and white matter degeneration. Moreover, we review functional brain changes by examining functional MRI and nuclear medicine imaging studies. The current review provides up-to-date knowledge in this field and summarizes the possible mechanisms responsible for FOG in PD.

Keywords: Freezing of gait; MRI; PET; Parkinson's disease; SPECT.

Fig. 1

Flow Chart. Following PRISMA guidelines, this flowchart displays the procedure to identify those studies that were suitable to be included in the systematic review.* Five studies report both structural and functional MRI analysis and are counted twice, thus total number of studies seems erroneously to be n = 63, while being n = 58.** Three studies report both grey and white matter analysis and are counted twice. Therefore, the correct number of structural MRI studies (on both grey and white matter) is n = 22, not n = 25.