Freezing of gait in Parkinson's disease: functional neuroimaging studies of the frontal lobe.

OBJECTIVE: The objective of the study is to study a group of patients with Parkinson's disease (PD) with and without freezing of gait (FOG) and analyze neuropsychological differences, especially regarding executive functions, according to their performance in a set of tests, and potential anomalies in functional positron emission tomography with 2-deoxy-2-[fluorine-18]fluoro-d-glucose integrated with computed tomography (18 F-FDG PET/CT) neuroimaging results of the frontal lobe.

METHODS: The study recruited 23 patients. We performed an 18 F-FDG PET/CT scan for 17 patients (9 with FOG and 8 without FOG) and 6 controls. Frontal functions were evaluated in all the patients during their 'on' situation.

RESULTS: In FDG PET studies, PD patients differed from controls in that they presented hypometabolic areas in the parietal and bilateral occipital regions, as well as in the bilateral frontal region, especially on the right side. Compared to patients without FOG, patients with FOG displayed more pronounced frontal and predominantly right-sided hypometabolism. Both groups of patients displayed a poorer performance than the control population in the frontal cognitive tests. A greater executive disfunction was found in patients with FOG.

CONCLUSIONS: Our study revealed greater hypometabolism in FDG PET studies, predominantly in right-sided-specific motor regions of the frontal lobe in FOG patients and greater frontal disfunction in neuropsychological tests in PD patients with FOG. These data suggest that FOG may be related to functional impairment of the circuits connecting the frontal lobe and the basal ganglia.