A new phenotype of choreic syndrome associating severe freezing of gait and chorea.

The early onset of gait akinesia should not rule out the diagnosis of hereditary chorea. It would be helpful to proceed to a whole-genome and long-read sequencing in order to track a new pathogenic variant including noncoding repeat expansion.

Effect of Trunk Muscle Strengthening on Gait Pattern and Falls in Parkinson's Disease.

BACKGROUND: The course of Parkinson's disease is characterized by gait disturbance and falls, which affect patients' quality of life and engender high healthcare costs. These factors are not greatly improved by levodopa therapy or deep brain stimulation of the subthalamic nuclei. Indeed, the symptoms may even worsen with these treatment. Physiotherapy may be the most appropriate treatment to reduce the incidence of falls in these cases; however, its benefits are modest. OBJECTIVE: To assess the effectiveness of trunk muscle strengthening in 10 patients with Parkinson's disease being treated with deep brain stimulation of the subthalamic nuclei who are affected by gait disturbances and falls. METHOD: A standardized physiotherapy programme centred on trunk muscle strengthening was conducted. Its effectiveness was assessed using a clinical approach combined with video-based motion analysis. RESULTS: After 4 weeks of trunk muscle strengthening, the gait item on the Unified Parkinson's Disease Rating Scale (UPDRS, part 3) together with several gait kinematic parameters (step length, walking cycle duration variability, gait speed) were significantly improved and the number of falls decreased. CONCLUSION: These preliminary findings suggest that physiotherapy centred on rachis mobility improves the quality of gait and reduces the number of falls in patients with Parkinson's disease who are being treated with deep brain stimulation of the subthalamic nuclei. This is a potentially useful supplement to the traditional physiotherapy approach, in addition to the pharmacological and surgical treatment of Parkinson's disease.

3-D motion capture for long-term tracking of spontaneous locomotor behaviors and circadian sleep/wake rhythms in mouse.

BACKGROUND: Locomotor activity provides an index of an animal's behavioral state. Here, we report a reliable and cost-effective method that allows long-term (days to months) simultaneous tracking of locomotion in mouse cohorts (here consisting of 24 animals). NEW METHOD: The technique is based on a motion capture system used mainly for human movement study. A reflective marker was placed on the head of each mouse using a surgical procedure and labeled animals were returned to their individual home cages. Camera-recorded data of marker displacement resulting from locomotor movements were then analyzed with custom built software. To avoid any data loss, data files were saved every hour and automatically concatenated. Long-term recordings (up to 3 months) with high spatial (<1mm) and temporal (up to 100Hz) resolution of animal movements were obtained. RESULTS: The system was validated by analyzing the spontaneous activity of mice from post-natal day 30-90. Daily motor activity increased up to 70days in correspondence with maturational changes in locomotor performance. The recorded actigrams also permitted analysis of circadian and ultradian rhythms in cohort sleep/wake behavior. COMPARISON WITH EXISTING METHOD(S): In contrast to traditional session-based experimental approaches, our technique allows locomotor activity to be recorded with minimal experimenter manipulation, thereby minimizing animal stress. CONCLUSIONS: Our method enables the continuous long-term (up to several months) monitoring of tens of animals, generating manageable amounts of data at minimal costs without requiring individual dedicated devices. The actigraphic data collected allows circadian and ultradian analysis of sleep/wake behaviors to be performed.

Evaluation of Motor Skills in Children with Rubinstein-Taybi Syndrome.

Rubinstein-Taybi syndrome (RTS) is a rare genetic disease that associates intellectual disability with somatic characteristics. We have conducted a study of the overall motor abilities of RTS participants. Static postural performance as well as gait parameters were somewhat decreased, although not significantly compared to typically developing (TD) participants. In contrast, the motor skills requiring a high level of visuomotor coordination were considerably degraded in RTS participants compared to TD participants. We also found that cognitive status was significantly correlated with performance for tasks requiring a higher level of visuomotor coordination in RTS but not TD participants. Our study demonstrates a reduction in the motor performance of RTS participants and a link between the level of intellectual disability and motor capacities.

The influence of scopolamine on motor control and attentional processes.

BACKGROUND: Motion sickness may be caused by a sensory conflict between the visual and the vestibular systems. Scopolamine, known to be the most effective therapy to control the vegetative symptoms of motion sickness, acts on the vestibular nucleus and potentially the vestibulospinal pathway, which may affect balance and motor tasks requiring both attentional process and motor balance. The aim of this study was to explore the effect of scopolamine on motor control and attentional processes. METHODS: Seven subjects were evaluated on four different tasks before and after a subcutaneous injection of scopolamine (0.2 mg): a one-minute balance test, a subjective visual vertical test, a pointing task and a galvanic vestibular stimulation with EMG recordings. RESULTS: The results showed that the reaction time and the movement duration were not modified after the injection of scopolamine. However, there was an increase in the center of pressure displacement during the balance test, a decrease in EMG muscle response after galvanic vestibular stimulation and an alteration in the perception of verticality. DISCUSSION: These results confirm that low doses of scopolamine such as those prescribed to avoid motion sickness have no effect on attentional processes, but that it is essential to consider the responsiveness of each subject. However, scopolamine did affect postural control and the perception of verticality. In conclusion, the use of scopolamine to prevent motion sickness must be considered carefully because it could increase imbalances in situations when individuals are already at risk of falling (e.g., sailing, parabolic flight).

Early GABAergic transmission defects in the external globus pallidus and rest/activity rhythm alteration in a mouse model of Huntington's disease.

Huntington's disease (HD) is characterized by progressive motor symptoms preceded by cognitive deficits and is regarded as a disorder that primarily affects the basal ganglia. The external globus pallidus (GPe) has a central role in the basal ganglia, projects directly to the cortex, and is majorly modulated by GABA. To gain a better understanding of the time course of HD progression and gain insight into the underlying mechanisms, we analyzed GABAergic neurotransmission in the GPe of the R6/1 mouse model at purportedly asymptomatic and symptomatic stages (i.e., 2 and 6months). Western blot and quantitative polymerase chain reaction (PCR) analyses revealed alterations in the GPe of male R6/1 mice compared with wild-type littermates. Expression of proteins involved in pre- and post-synaptic GABAergic compartments as well as synapse number were severely decreased at 2 and 6months. At both ages, patch-clamp electrophysiological recordings showed a decrease of spontaneous and miniature inhibitory post-synaptic currents (IPSCs) suggesting that HD mutation has an early effect on the GABA signaling in the brain. Therefore, we performed continuous locomotor activity recordings from 2 to 4months of age. Actigraphy analyses revealed rest/activity fragmentation alterations that parallel GABAergic system impairment at 2months, while the locomotor deficit is evident only at 3months in R6/1 mice. Our results reveal early deficits in HD and support growing evidence for a critical role played by the GPe in physiological and pathophysiological states. We suggest that actimetry may be used as a non-invasive tool to monitor early disease progression.

Is "circling" behavior in humans related to postural asymmetry?

In attempting to walk rectilinearly in the absence of visual landmarks, persons will gradually turn in a circle to eventually become lost. The aim of the present study was to provide insights into the possible underlying mechanisms of this behavior. For each subject (N = 15) six trajectories were monitored during blindfolded walking in a large enclosed area to suppress external cues, and ground irregularities that may elicit unexpected changes in direction. There was a substantial variability from trial to trial for a given subject and between subjects who could either veer very early or relatively late. Of the total number of trials, 50% trajectories terminated on the left side, 39% on the right side and 11% were defined as "straight". For each subject, we established a "turning score" that reflected his/her preferential side of veering. The turning score was found to be unrelated to any evident biomechanical asymmetry or functional dominance (eye, hand...). Posturographic analysis, used to assess if there was a relationship between functional postural asymmetry and veering revealed that the mean position of the center of foot pressure during balance tests was correlated with the turning score. Finally, we established that the mean position of the center of pressure was correlated with perceived verticality assessed by a subjective verticality test. Together, our results suggest that veering is related to a "sense of straight ahead" that could be shaped by vestibular inputs.

Maximal and sustained isokinetic lower-limb muscle strength in hospitalized older people.

Maximal strength decreases with aging whereas sustained strength is less affected. Strength decline may be worsened by hospitalization. The aim of this study was to estimate the maximal and sustained isokinetic muscle strength of lower limbs in hospitalized elderly subjects. We evaluated 43 hospitalized elderly subjects (86 +/- 5 years), 28 elderly community-dwelling control subjects (75.4 +/- 6.2 years), and 25 young subjects (28.2 +/- 3.7 years). Among hospitalized subjects, 30 underwent isokinetic evaluation at clinical stability (T0) and again 1 month later (T1). Maximal peak torque (MPT) of the plantarflexors was measured at 30 degrees and 60 degrees /s, and knee flexors and extensors at 90 degrees /s. Evolution of the MPT and the endurance coefficient (EC) on 20 repetitions of plantarflexion at 60 degrees /s were calculated. MPT of plantarflexors and knee flexors and extensors had improved at T1 compared with T0, in hospitalized subjects. MPT evolution and EC values during the sustained strength test revealed no decrease in strength over time in hospitalized subjects at T0 and at T1 compared with community-dwelling control subjects and young subjects. In hospitalized subjects, the absence of an initial phase of fast decrease in muscle strength, which is observed in young subjects during the sustained strength test, could explain this result. It could be related to the modifications of muscle-fiber composition described in elderly subjects and enhanced by hospitalization.