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

Figures & data

Figure 1 Flow chart of all subjects through the study.

Abbreviations: PD, Parkinson’s disease; PET-CT, positron emission tomography–computed tomography; MRI, magnetic resonance imaging; MSA, multisystem atrophy; PSP, progressive nuclear paralysis; INPH, idiopathic normal pressure hydrocephalus; FOG, freezing of gait.

Table 1 Analysis of clinical characteristics in PD patients with FOG

Characteristic	Before adjustment			After adjustment
	FOG group	Non-FOG group	p	FOG group	Non-FOG group	p
Age (years), mean±SD	66.90±1.51	56.33±0.98	0.00	66.86±2.57	56.46±0.94	0.00
Age of onset (years), mean±SD	56.25±3.20	52.47±1.15	0.26	56.17±3.12	52.48±1.15	0.27
Duration	10.65±2.25	3.86±0.38	0.00	11.93±1.23	3.69±0.44	0.00
≤2 years, n (%)	3 (4.17)	69 (95.83)
2–10 years, n (%)	9 (11.54)	69 (88.46)
≥10 years, n (%)	8 (47.06)	9 (52.94)
Sex
Male, n (%)	11 (11.22)	87 (88.78)	0.72	11 (11.22)	87 (88.78)	0.88
Female, n (%))	9 (13.04)	60 (86.96)		9 (13.04)	60 (86.96)
Hoehn–Yahr stage	2.25±0.12	1.99±0.06	0.10	2.20±0.15	2.00±0.06	0.21
UPDRS	59.25±1.96	68.30±4.95	0.53	47.53±12.36	69.72±4.21	0.09
UPDRS-III	43.36±4.02	37.30±1.39	0.18	41.04±4.29	37.54±1.36	0.44
MMSE	22.41±1.49	27.09±0.34	0.00	23.49±1.04	26.96±0.35	0.00
MoCA	20.29±1.15	24.60±0.37	0.00	21.63±1.03	24.43±0.35	0.01
Equivalent levodopa dose (mg)	704.08±51.34	535.59±29.61	0.04	738.56±80.37	530.90±28.68	0.02

Notes: Single-factor analysis by variance and chi-square analysis. Adjusting confounding factors by covariate and logistic analysis. *p<0.05.

Abbreviations: PD, Parkinson’s disease; FOG, freezing of gait; UPDRS, unified Parkinson's disease rating scale; MMSE, Mini-Mental State Examination; MoCA, Montreal Cognitive Assessment.

Table 2 Uptake ratio of VMAT2 distribution by ¹⁸F-FDG PET-CT in PD patients with FOG

Brain region	Before adjustment			After adjustment
	FOG group	Non-FOG group	p	FOG group	Non-FOG group	p
Caudate nucleus	4.43±0.25	5.36±0.14	0.02	4.74±0.36	5.32±0.14	0.15
Putamen	6.51±0.29	7.46±0.26	0.07	6.26±0.51	7.52±0.18	0.02
Anterior putamen	3.59±0.17	4.18±0.11	0.05	3.50±0.29	4.20±0.10	0.02
Dorsal putamen	2.92±0.15	3.30±0.10	0.15	2.77±0.25	3.32±0.09	0.04

Notes: Single-factor analysis by variance and adjusting confounding factors by covariate analysis. *p<0.05.

Abbreviations: ¹⁸F-FDG PET-CT, 18-fludeoxyglucose positron emission tomography–computed tomography; PD, Parkinson’s disease; FOG, freezing of gait.

Figure 2 Activities of VMAT2 between the two groups.

Abbreviation: FOG, freezing of gait.

Figure 3 PET-CT image of VMAT2 distribution in a Hoehn–Yahr stage 3 patient with freezing of gait. Two white arrows indicate severe dopamine decline of bilateral putamens in cases.

Abbreviation: PET-CT, positron emission tomography–computed tomography.

Figure 4 PET-CT image of VMAT2 distribution in a Hoehn–Yahr stage 3 patient without freezing of gait. Two white arrows show the dopamine decline of bilateral putamen.

Abbreviation: PET-CT, positron emission tomography–computed tomography.

Figure 5 PET-CT image of VMAT2 distribution in a normal person. Two white arrows show the normal dopamine level of bilateral putamen.

Abbreviation: PET-CT, positron emission tomography–computed tomography.

Table 3 Uptake ratios of different brain regions by ¹⁸F-FDG PET-CT in PD patients with FOG

Brain region	Before adjustment			After adjustment
	FOG group	Non-FOG group	p	FOG group	Non-FOG group	p
Midbrain	0.85±0.03	0.84±0.01	0.49	0.87±0.02	0.84±0.01	0.14
Caudate nucleus	1.10±0.03	1.07±0.01	0.16	1.12±0.02*	1.06±0.01	0.03
Lentiform nucleus	1.41±0.04*	1.32±0.01	0.01	1.40±0.03*	1.33±0.01	0.045
Thalamus	1.21±0.04	1.18±0.01	0.21	1.21±0.03	1.18±0.01	0.18
Medial frontal cortex	1.15±0.03	1.13±0.01	0.64	1.14±0.03	1.13±0.01	0.85
Superior frontal cortex	1.14±0.04	1.10±0.01	0.21	1.14±0.03	1.10±0.01	0.27
Middle frontal cortex	1.24±0.04	1.21±0.01	0.30	1.24±0.03	1.21±0.01	0.36
Inferior frontal cortex	1.22±0.03*	1.17±0.01	0.06	1.22±0.03	1.17±0.01	0.06
Sensorimotor cortex	1.16±0.03	1.12±0.01	0.08	1.16±0.03	1.12±0.01	0.16
Broca region	1.24±0.04	1.20±0.01	0.25	1.24±0.03	1.20±0.01	0.29
Anterior cingulate cortex	1.15±0.03	1.17±0.01	0.69	1.16±0.03	1.17±0.01	0.74
Posterior cingulate cortex	1.36±0.04	1.34±0.01	0.67	1.35±0.04	1.34±0.01	0.86
Superior parietal cortex	1.06±0.03	1.01±0.01	0.06	1.04±0.02	1.02±0.01	0.23
Inferior parietal cortex	1.10±0.03	1.05±0.01	0.10	1.09±0.03	1.06±0.01	0.19
Parietal temporal cortex	1.15±0.04	1.12±0.01	0.31	1.16±0.03	1.12±0.01	0.20
Superior lateral temporal cortex	1.21±0.03	1.17±0.01	0.19	1.21±0.03	1.17±0.01	0.17
Inferior lateral anterior temporal cortex	1.00±0.03	0.97±0.01	0.27	1.01±0.02	0.97±0.01	0.12
Inferior lateral posterior temporal cortex	1.07±0.03	1.05±0.01	0.35	1.08±0.02	1.05±0.01	0.21
Anterior medial temporal cortex	0.82±0.02	0.81±0.07	0.55	0.83±0.02	0.81±0.01	0.21
Posterior medial temporal cortex	1.02±0.03	0.98±0.01	0.34	1.02±0.02	1.00±0.01	0.19
Primary visual cortex	1.18±0.06*	1.27±0.01	0.04	1.19±0.04*	1.27±0.02	0.049
Associated visual cortex	1.17±0.04	1.15±0.01	0.63	1.17±0.03	1.15±0.01	0.59

Notes: Single-factor analysis by variance and adjusting confounding factors by covariate analysis. *p<0.05.

Abbreviations: ¹⁸F-FDG PET-CT, 18-fludeoxyglucose positron emission tomography–computed tomography; PD, Parkinson’s disease; FOG, freezing of gait.

Figure 6 Activities of different brain regions between the two groups.

Abbreviation: FOG, freezing of gait.

Figure 7 PET-CT image of Hoehn–Yahr stage 3 patient with freezing of gait. Two white arrows show hypometabolism of bilateral primary visualcortex.

Abbreviation: PET-CT, positron emission tomography–computed tomography.

Figure 8 PET-CT imageof Hoehn–Yahr stage 3 patient without freezing of gait. Two white arrows indicate hypermetabolism of bilateral primary visualcortex.

Abbreviation: PET-CT, positron emission tomography–computed tomography.

Figure 9 PET-CT image of a normal person. Two white arrows show the normal metabolism of primary visualcortex.

Abbreviation: PET-CT, positron emission tomography–computed tomography.