Focal dystonia : sensory-motor dysfunctions and consequences on the organization of movement

L’identification des muscles responsables des dystonies focales est un prérequis à l’instauration des traitements par toxine botulique et exercices correcteurs. A partir de deux dystonies apparemment dissemblables: la crampe de l’écrivain et la dystonie cervicale, nous avons montré que la réponse aux traitements est tributaire de la distribution des muscles impliqués. L’enregistrement des mouvements du segment tête-cou dans la dystonie cervicale , au moyen de capteurs inertiels 3-D, a montré qu’au mouvement volontaire de la tête, dans un plan, s’associent des mouvements non physiologiques dans les deux autres plans. Pour déterminer les actions musculaires en cause, nous avons réalisé une modélisation numérique du segment tête-cou permettant d’associer le muscle responsable aux déformations. Par ailleurs, sachant l’importance des phénomènes sensitifs dans le contrôle du mouvement, nous avons, au cours de tâches d’ajustement de la force musculaire, montré que ce contrôle de la force est perturbé dans chacune des deux dystonies focales étudiées.Nos résultats devraient avoir une implication dans les traitements symptomatiques de ces dystonies.The identification of the muscles responsible for focal dystonia is a prerequisite to the introduction of botulinum toxin treatment and tailored exercises. From two apparently dissimilar dystonia: writer's cramp and cervical dystonia, we showed that the response to the treatments depends on the distribution of the muscles involved. Recording the movement of the head-neck segment in cervical dystonia, using 3-D inertial sensors, showed that voluntary head movement in a plane is associated with non-physiological movement in the two other planes. To determine the muscular actions involved, we performed a digital modeling of the head-neck segment which allows us to link the responsible muscle with abnormal postures.Therefore, knowing the importance of sensory phenomena in the control of movement, we have, during tasks of muscular force adjustment, demonstrated that force control is altered in both studied dystonia.Our results should have implications in the symptomatic treatment of these dystonias

"Pays" et territoires : de Vidal de la Blache aux lois d'aménagement et de développement du territoire

National audienc

Kinematic analysis of the head by inertial sensors. Test-retest reproducibility and clinical use feasibility

The aim of this study was to evaluate the reproducibility of a protocol using inertial sensors in order to characterize primary and associated movements of the head. Twenty-two subjects were evaluated twice in the same experimental conditions (3 days interval). Two inertial sensors allowed the evaluation of the range of movement of the head. Three complete cycles of movements were realised in each plane. A patient suffering from cervical dystonia was also evaluated with the same protocol before and after self-training program. Results show a good reproducibility for all ranges of movement except for the associated movements realised in the sagittal plane. Thereafter, our protocol allowed us to notice an improvement of the kinematics of the head after the self-training program followed by the patient. These results show the reproducibility of the inertial sensors as evaluation tools for head movements, a change in the proposed method will allow a generalization to cervical movements

Repositioning errors of the head in straight-ahead position in cervical dystonia: Influence of clinical features and movement planes

International audienc

Physiological impacts of modulating phosphoenolpyruvate carboxylase levels in leaves and seeds of Arabidopsis thaliana

International audienc

Upper Limb Outcome Measures Used in Stroke Rehabilitation Studies: A Systematic Literature Review

<div><p>Background</p><p>Establishing which upper limb outcome measures are most commonly used in stroke studies may help in improving consensus among scientists and clinicians.</p><p>Objective</p><p>In this study we aimed to identify the most commonly used upper limb outcome measures in intervention studies after stroke and to describe domains covered according to ICF, how measures are combined, and how their use varies geographically and over time.</p><p>Methods</p><p>Pubmed, CinHAL, and PeDRO databases were searched for upper limb intervention studies in stroke according to PRISMA guidelines and477 studies were included.</p><p>Results</p><p>In studies 48different outcome measures were found. Only 15 of these outcome measures were used in more than 5% of the studies. The Fugl-Meyer Test (FMT)was the most commonly used measure (in 36% of studies). Commonly used measures covered ICF domains of body function and activity to varying extents. Most studies (72%) combined multiple outcome measures: the FMT was often combined with the Motor Activity Log (MAL), the Wolf Motor Function Test and the Action Research Arm Test, but infrequently combined with the Motor Assessment Scale or the Nine Hole Peg Test. Key components of manual dexterity such as selective finger movements were rarely measured. Frequency of use increased over a twelve-year period for the FMT and for assessments of kinematics, whereas other measures, such as the MAL and the Jebsen Taylor Hand Test showed decreased use over time. Use varied largely between countries showing low international consensus.</p><p>Conclusions</p><p>The results showed a large diversity of outcome measures used across studies. However, a growing number of studies used the FMT, a neurological test with good psychometric properties. For thorough assessment the FMT needs to be combined with functional measures. These findings illustrate the need for strategies to build international consensus on appropriate outcome measures for upper limb function after stroke.</p></div

Does dystonic muscle activity affect sense of effort in cervical dystonia?

BACKGROUND:Focal dystonia has been associated with deficient processing of sense of effort cues. However, corresponding studies are lacking in cervical dystonia (CD). We hypothesized that dystonic muscle activity would perturb neck force control based on sense of effort cues. METHODS:Neck extension force control was investigated in 18 CD patients with different clinical features (7 with and 11 without retrocollis) and in 19 control subjects. Subjects performed force-matching and force-maintaining tasks at 5% and 20% of maximum voluntary contraction (MVC). Three task conditions were tested: i) with visual force feedback, ii) without visual feedback (requiring use of sense of effort), iii) without visual feedback, but with neck extensor muscle vibration (modifying muscle afferent cues). Trapezius muscle activity was recorded using electromyography (EMG). RESULTS:CD patients did not differ in task performance from healthy subjects when using visual feedback (ANOVA, p>0.7). In contrast, when relying on sense of effort cues (without visual feedback, 5% MVC), force control was impaired in patients without retrocollis (p = 0.006), but not in patients with retrocollis (p>0.2). Compared to controls, muscle vibration without visual feedback significantly affected performance in patients with retrocollis (p<0.001), but not in patients without retrocollis. Extensor EMG during rest, included as covariate in ANOVA, explained these group differences. CONCLUSION:This study shows that muscle afferent feedback biases sense of effort cues when controlling neck forces in patients with CD. The bias acts on peripheral or central sense of effort cues depending on whether the task involves dystonic muscles. This may explain why patients with retrocollis more accurately matched isometric neck extension forces. This highlights the need to consider clinical features (pattern of dystonic muscles) when evaluating sensorimotor integration in CD

Structural abnormalities in the cerebellum and sensorimotor circuit in writer's cramp.

International audienceBACKGROUND: Structural abnormalities were detected in bilateral primary sensorimotor areas in writer's cramp. Evidence in other primary dystonia, including blepharospasm and cervical dystonia, suggest that structural abnormalities may be observed in other brain areas such as the cerebellum in writer's cramp. OBJECTIVE: To test the hypothesis that structural abnormalities are present along the sensorimotor and cerebellar circuits in patients with writer's cramp. METHODS: Using voxel-based morphometry, the authors compared the brain structure of 30 right-handed patients with writer's cramp with that of 30 healthy control subjects matched for gender, age, and handedness. RESULTS: Gray matter decrease was found in the hand area of the left primary sensorimotor cortex, bilateral thalamus, and cerebellum (height threshold p < 0.01, cluster significant at p < 0.05 corrected for multiple comparisons). CONCLUSIONS: These results demonstrate in writer's cramp the presence of structural abnormalities in brain structures interconnected within the sensorimotor network including the cerebellum and the cortical representation of the affected hand. These abnormalities may be related to the pathophysiology of writer's cramp, questioning the role of the cerebellum, or to maladaptive plasticity in a task-related dystonia