Subliminal gait initiation deficits in rapid eye movement sleep behavior disorder: A harbinger of freezing of gait?

Abstract

Background Muscle activity during REM sleep is markedly increased in people with REM sleep behavior disorder (RBD) and people with Parkinson’s disease (PD) who have freezing of gait. This study examined if individuals with RBD, who do not have a diagnosis of PD, show abnormalities in gait initiation that resemble the impairments observed in PD and whether there is a relationship between these deficits and the level of REM sleep without atonia. Methods Gait initiation and polysomnography studies were conducted in four groups of 10 subjects each: RBD, PD with and without freezing of gait and control subjects. Results Significant reductions were seen in the posterior shift of the center of pressure during the propulsive phase of gait initiation in the RBD and PD with freezing of gait groups compared with controls and PD non-freezers. These reductions negatively correlated with the amount of REM sleep without atonia. The duration of the initial dorsiflexor muscle burst during gait initiation was significantly reduced in both PD groups and the RBD cohort. Conclusions These results provide evidence that people with RBD, prior to a diagnosis of a degenerative neurologic disorder, show alterations in the coupling of posture and gait similar to those seen in PD. The correlation between increased REM sleep without atonia and deficits in forward propulsion during the push-off phase of gait initiation suggests that abnormities in the regulation of muscle tone during REM sleep may be related to the pathogenesis of freezing of gait.

Effect of Cue Timing and Modality on Gait Initiation in Parkinson Disease With Freezing of Gait

“…5,11,31 Previous studies have also shown deficits in step execution in people with FOG. 11,32 Therefore, impaired APAs are common to PD, with FOG causing additional deficits during step execution (push-off and first step).…”

Freezing of gait in Parkinson’s disease: pathophysiology, risk factors and treatments

“…However, multivariable analysis in the same study failed to establish its risk factor effect [16]. Although gait disorders have been found in polysomnographyconfirmed RBD patients [46,47] and it was hypothesized that FOG and RBD might share a common physiopathology [48], the relationship between RBD and FOG was not confirmed [16,18,24]. In other two studies, RBDSQ at baseline didn't show significant difference between transitional freezers and non-freezers [18,24], which was supported by a previous finding that there was no freezing difference between the patients with probable RBD and without RBD [49].…”

REM Sleep Behavior Disorder: Diagnosis, Clinical Implications, and Future Directions

“…21,87 Isolated RSWA has been associated with positive neurodegenerative biomarkers such as loss of smell or color vision 88 and has been associated with gait freezing and cognitive impairment in PD. 89,90 Rapid eye movement sleep without atonia amounts have also been shown to progress over time in patients with idiopathic RBD 91 and have been associated with a higher risk of phenoconversion to PD in idiopathic RBD. 92 Isolated RSWA may also phenoconvert to idiopathic RBD, as shown in a recent study, with 7% to 14% of patients developing clinical RBD during longitudinal follow-up.…”

“…23,30,31,41,42,45,89,99–101 In addition, neuropsychological deficits of dysexecutive, attentional, visuoperceptual, and short-term memory impairments appear to progress over time, 38,44,96,102–107 and neurophysiological markers such as electroencephalographic slowing, 108–111 and neuroimaging studies have also demonstrated findings indicating likely underlying synucleinopathy pathology.…”