Journal of neurology
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Journal of neurology · Jul 2015
Disentangling perceptual judgment and online feedback deficits in Parkinson's freezing of gait.
Although the underlying mechanisms of freezing of gait in Parkinson's disease (PD) are not fully understood, impaired sensory-perceptual processing has been proposed as an important contributor to freezing episodes. The aims of this cross-sectional study were to disentangle how sensory-perceptual deficits involved in planning (prior to movement) and sensory-perceptual feedback processing (during movement execution) contribute to freezing of gait in narrow spaces. Thirteen PD participants with freezing (PD FOG), 14 PD participants without freezing (PD non-FOG), and 15 healthy individuals made a perceptual estimate of the width of the distal opening of a corridor in two conditions: parallel and narrowing walls. ⋯ Although a similar number of freezing episodes occurred in both corridor conditions, PD FOG had greater step length variability while walking through the parallel walls corridor compared to healthy (p < 0.001) and PD non-FOG (p = 0.017) participants. Regression analysis revealed that error variability in perceptual judgment predicted the percentage of time spent in double support (R (2) = 0.347) only in the narrowing walls condition for PD FOG. These results support the notion that sensory-perceptual deficits both prior to movement planning and during movement execution are important factors contributing to freezing of gait.
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Journal of neurology · Jul 2015
Cognitive impairment and memory disorders in relapsing-remitting multiple sclerosis: the role of white matter, gray matter and hippocampus.
Cognitive disorders occur in up to 65 % of multiple sclerosis (MS) patients; they have been correlated with different MRI measures of brain tissue damage, whole and regional brain atrophy. The hippocampal involvement has been poorly investigated in cognitively impaired (CI) MS patients. The objective of this study is to analyze and compare brain tissue abnormalities, including hippocampal atrophy, in relapsing-remitting MS (RRMS) patients with and without cognitive deficits, and to investigate their role in determining cognitive impairment in MS. ⋯ Compared to CP, CI RRMS patients showed higher T2-LL (p = 0.02) and WM atrophy (p = 0.01). In the whole RRMS group, several cognitive tests correlated with brain tissue abnormalities (T2-LL, WM and GM atrophy); only verbal memory performances correlated with left hippocampal atrophy. Our results emphasize the role of T2-LL and WM atrophy in determining clinically evident cognitive impairment in MS patients and provide evidence that GM and hippocampal atrophy occur in MS patients regardless of cognitive status.