Abstract
Pure akinesia with gait freezing (PAGF) is considered a clinical phenotype of progressive supranuclear palsy. The brain atrophy and cognitive deficits in PAGF are expected to be less prominent than in classical Richardson's syndrome (RS), but this hypothesis has not been explored yet. We reviewed the medical records of 28 patients with probable RS, 19 with PAGF, and 29 healthy controls, and compared cortical thickness, subcortical gray matter volume, and neuropsychological performance among the three groups. Patients with PAGF had thinner cortices in frontal, inferior parietal, and temporal areas compared with controls; however, areas of cortical thinning in PAGF patients were less extensive than those in RS patients. In PAGF patients, hippocampal, and thalamic volumes were also smaller than controls, whereas subcortical gray matter volumes in PAGF and RS patients were comparable. In a comparison of neuropsychological tests, PAGF patients had better cognitive performance in executive function, visual memory, and visuospatial function than RS patients had. These results demonstrate that cognitive impairment, cortical thinning, and subcortical gray matter atrophy in PAGF patients resemble to those in RS patients, though the severity of cortical thinning and cognitive dysfunction is milder. Our results suggest that, PAGF and RS may share same pathology but that it appears to affect a smaller proportion of the cortex in PAGF.
Highlights
Pure akinesia was first described by Imai et al in 1974, and their cases were characterized by freezing or blocking during gait, speaking, and writing (Imai and Narabayashi, 1974; Williams et al, 2007)
pure akinesia with gait freezing (PAGF) patients had cortical thinning in frontal, inferior parietal, and temporal areas compared with controls; the areas of cortical thinning in patients with PAGF were less extensive than in Richardson’s syndrome (RS) patients
In a comparison of neuropsychological tests, PAGF patients had better cognitive performance in frontal executive function, visual memory, and visuospatial function than did RS patients. These data suggest that PAGF may involve a similar pathological burden in subcortical gray matter as in RS but that this pathology may occur in a more limited cortical area than in RS, which may underlie the difference in cognitive performance
Summary
Pure akinesia was first described by Imai et al in 1974, and their cases were characterized by freezing or blocking during gait, speaking, and writing (Imai and Narabayashi, 1974; Williams et al, 2007). Patients did not respond to levodopa, nor did they display other characteristics of parkinsonism including limb rigidity, resting tremor, cognitive impairment, or abnormal eye movement. Since this initial description, many similar cases have been reported using various terms including pure akinesia (Imai et al, 1987; Matsuo et al, 1991; Riley et al, 1994), primary progressive freezing of gait (Achiron et al, 1993; Factor et al, 2006), and gait ignition failure. The authors suggested that PAGF should be considered the third phenotype of PSP
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