Papers by Dorothy Barthélemy
Progress in Brain Research, 2011
Locomotion is a very robust motor pattern which can be optimized after different types of lesions... more Locomotion is a very robust motor pattern which can be optimized after different types of lesions to the central and/or peripheral nervous system. This implies that several plastic mechanisms are at play to re-express locomotion after such lesions. Here, we review some of the key observations that helped identify some of these plastic mechanisms. At the core of this plasticity is the existence of a spinal central pattern generator (CPG) which is responsible for hindlimb locomotion as observed after a complete spinal cord section. However, normally, the CPG pattern is adapted by sensory inputs to take the environment into account and by supraspinal inputs in the context of goal-directed locomotion. We therefore also review some of the sensory and supraspinal mechanisms involved in the recovery of locomotion after partial spinal injury. We particularly stress a recent development using a dual spinal lesion paradigm in which a first partial spinal lesion is made which is then followed, some weeks later, by a complete spinalization. The results show that the spinal cord below the spinalization has been changed by the initial partial lesion suggesting that, in the recovery of locomotion after partial spinal lesion, plastic mechanisms within the spinal cord itself are very important.
Background: After a traumatic brain injury, disturbances in the attentional processes have a dire... more Background: After a traumatic brain injury, disturbances in the attentional processes have a direct negative effect on functional recovery and on return to complex activities. To date, there is no good attention remediation treatment available. The primary objective of this review and pilot study is to get a comprehensive analysis and to evaluate the feasibility of implementing a tDCS protocol to improve attention disorders in patients with mild complicated to severe subacute TBI, hospitalized in an inpatient rehabilitation facility. Our secondary objective is to extract preliminary data and observational information on participants' response to treatment. Methods: Participants were recruited from a consecutive series of patients admitted to the TBI unit of a subspecialized regional rehabilitation center. They received a 20-minute tDCS stimulation 3 times a week for 3 weeks. A neuropsychological evaluation was performed before and after the intervention. We collected participants' socio-demographic and clinical characteristics as well as information about satisfaction, tolerability and adverse effects. Results: 164 patients were admitted between September 2018 and January 2020. 158 were excluded and 6 patients with presumed attentional de cits were enrolled. None completed the protocol as intended. No major side effects occurred. Conclusion: Non-invasive brain neurostimulation is promising to enhance attention de cits in patients with TBI. Implementation of a tDCS protocol to ful ll this purpose in an intensive inpatient rehabilitation center has its limitations. We made recommendations to facilitate the implementation of similar projects in the future.
Brain Stimulation, Jul 1, 2008
Disability and Rehabilitation
PURPOSE To determine the effectiveness of a single 10-min postural repositioning session on the m... more PURPOSE To determine the effectiveness of a single 10-min postural repositioning session on the maximum phonation duration (MPD) of the vowel/a/in individuals with acquired dysarthria. MATERIALS AND METHODS A pre-post interventional design was implemented; five patients with dysarthria (PWDs) underwent a single 2-hour experimental session. MPD capacities were assessed before and immediately after a 10-min postural repositioning intervention by a physical and occupational therapist. Five age- and sex-matched individuals without dysarthria were recruited as controls. The main outcome measure was the MPD of the vowel/a/at conversational and louder voice levels, with a speech-and-language therapist standing 1 and 6 m away, respectively. Secondary outcome measures were thoracic expansion, manometry, electromyographic recordings of axial muscles and perceived effort. RESULTS In PWDs, postural repositioning improved the MPD during the/a/-1-m (80.3% increase) and/a/-6-m tasks (18% increase), increased thoracic expansion and manometric measurements, and reduced the perceived effort necessary to perform the tasks. A triphasic electromyographic pattern was observed during both/a/-1-m and/a/-6-m tasks in controls, but was absent in participants with severe dysarthria, even after postural repositioning. Nonetheless, postural repositioning enabled an earlier onset of EMG activity prior to voice production. CONCLUSIONS These data suggest the efficacy of postural repositioning in improving phonatory capacities essential for voice production in PWDs.
Spinal cord, 2011
Cross-sectional descriptive analysis of magnetic resonance imaging (MRI) and clinical outcome. Th... more Cross-sectional descriptive analysis of magnetic resonance imaging (MRI) and clinical outcome. The aim of this study was to present anatomically consistent and independent spinal cord atrophy measures based on standard MRI material and analyze their specific relations to sensory and motor outcome in individuals with chronic incomplete spinal cord injury (SCI). Danish study on human SCI. We included 19 individuals with chronic incomplete SCI and 16 healthy controls. Participants underwent MRI and a neurological examination including sensory testing for light touch and pinprick, and muscle strength. Antero-posterior width (APW), left-right width (LRW) and cross-sectional spinal cord area (SCA) were extracted from MRI at the spinal level of C2. The angular variation of the spinal cord radius over the full circle was also extracted and compared with the clinical scores. The motor score was correlated to LRW and the sensory scores were correlated to APW. The scores correlated also well w...
Journal of Spinal Cord Medicine, Aug 2, 2023
Journal of Clinical Medicine
Proprioceptive cervicogenic dizziness (PCGD) is the most prevalent subcategory of cervicogenic di... more Proprioceptive cervicogenic dizziness (PCGD) is the most prevalent subcategory of cervicogenic dizziness. There is considerable confusion regarding this clinical syndrome’s differential diagnosis, evaluation, and treatment strategy. Our objectives were to conduct a systematic search to map out characteristics of the literature and of potential subpopulations of PCGD, and to classify accordingly the knowledge contained in the literature regarding interventions, outcomes and diagnosis. A Joanna Briggs Institute methodology-informed scoping review of the French, English, Spanish, Portuguese and Italian literature from January 2000 to June 2021 was undertaken on PsycInfo, Medline (Ovid), Embase (Ovid), All EBM Reviews (Ovid), CINAHL (Ebsco), Web of Science and Scopus databases. All pertinent randomized control trials, case studies, literature reviews, meta-analyses, and observational studies were retrieved. Evidence-charting methods were executed by two independent researchers at each s...
Progressive dorsoventral spinal lesions at L3 or L4 and restricted ventral lesions at L4 suggest ... more Progressive dorsoventral spinal lesions at L3 or L4 and restricted ventral lesions at L4 suggest that the integrity of the ventral or ventrolateral ftiniculi as well as the L3-L4 segments is critical for the induction of locomotion by [SMS at L5 to SI or DR stimulation.
Frontiers in Neural Circuits
Locomotion requires the complex involvement of the spinal and supraspinal systems. So far, the ro... more Locomotion requires the complex involvement of the spinal and supraspinal systems. So far, the role of vestibular input in gait has been assessed mainly with respect to gait stability. The noninvasive technique of galvanic vestibular stimulation (GVS) has been reported to decrease gait variability and increase gait speed, but the extent of its effect on spatiotemporal gait parameters is not fully known.Objective: Characterize vestibular responses during gait and determine the influence of GVS on cycle duration in healthy young participants.Methods: Fifteen right-handed individuals participated in the study. Electromyography (EMG) recordings of the bilateral soleus (SOL) and tibialis anterior muscles (TA) were performed. First, to determine stimulation intensity, an accelerometer placed on the vertex recorded the amplitude of the head tilts evoked by the GVS (1–4 mA, 200 ms) to establish a motor threshold (T). Second, while participants walked on a treadmill, GVS was applied at the o...
Magnetic Resonance in Medicine, 2012
Diffusion tensor imaging has been used in a number of spinal cord studies, but severe distortions... more Diffusion tensor imaging has been used in a number of spinal cord studies, but severe distortions caused by susceptibility induced field inhomogeneities limit its applicability to investigate small volumes within acceptable acquisition times. A way to evaluate image distortions is to map the point spread function of the voxel intensity in a reference scan. In this study, the point spread function was mapped for an echo-planar imaging sequence in the human cervical spinal cord with isotropic resolution and large field of view. Correction with the point spread function map improved anatomical consistency, and full cervical tractography was thereby possible from a C1 seed region in healthy controls and one individual with spinal cord injury. It is suggested that point spread function mapping of the spinal cord can be used in combination with sequence-based methods for reduction of susceptibility artifacts or in high-field imaging settings where off-resonance effects are pronounced. Magn Reson Med 000:000-000, 2012.
Archives of Physical Medicine and Rehabilitation, 2010
occupational therapy; therapeutic recreation; speech). The average therapist delivered 5.84Ϯ10.1 ... more occupational therapy; therapeutic recreation; speech). The average therapist delivered 5.84Ϯ10.1 treatment sessions (range, 1-155). Within the 6 disciplines, the average participation rating was higher for each successive treatment session of a particular patient by a particular therapist. This effect remained (except for therapeutic recreation) even after statistically controlling for the average rating the therapist gave out across all his/her patients; the average rating the patient received across all his/her treating clinicians; the number of days elapsed from admission and the number of days remaining until discharge. However, the amount of variance in the participation rating explained by the number of prior sessions was very small, before and after statistical controls. Conclusions: Familiarity appears not to breed contempt, but to allow therapists to get better participation out of their patients. Whether this is true or just appearance is unimportant; in both instances, better outcomes of the rehabilitation process are to be expected. More research, using therapist-, patient-and outside observercompleted measures of the quality of patient, and therapist efforts, is appropriate.
Journal of Neurophysiology, 2007
Intraspinal microstimulation (ISMS) through a single microelectrode can induce locomotion in cats... more Intraspinal microstimulation (ISMS) through a single microelectrode can induce locomotion in cats spinalized at T131 wk before (untrained) or after 3–5 wk of treadmill training. Here we study the optimal parameters of ISMS and the characteristics of locomotion evoked. ISMS was applied in the dorsal region of segments L3–S1at different lateralities (midline to 2.5 mm) and after an intravenous injection of clonidine (noradrenergic agonist). Kinematics and electromyographic recordings were used to characterize locomotion. ISMS could induce a bilateral locomotor pattern similar to that obtained with perineal stimulation, and the characteristics of locomotion varied according to the spinal segment stimulated. Mechanisms by which ISMS could evoke locomotion were then investigated by stimulating, inactivating, or lesioning different spinal structures. Dorsal root stimulation (DRS), just like ISMS, could evoke a variety of ipsi- and bilateral nonlocomotor movements as well as locomotor resp...
PLOS ONE, 2020
The vestibular system is essential to produce adequate postural responses enabling voluntary move... more The vestibular system is essential to produce adequate postural responses enabling voluntary movement. However, how the vestibular system influences corticospinal output during postural tasks is still unknown. Here, we examined the modulation exerted by the vestibular system on corticospinal output during standing. Healthy subjects (n = 25) maintained quiet standing, head facing forward with eyes closed. Galvanic vestibular stimulation (GVS) was applied bipolarly and binaurally at different delays prior to transcranial magnetic stimulation (TMS) which triggered motor evoked potentials (MEPs). With the cathode right/anode left configuration, MEPs in right Soleus (SOL) muscle were significantly suppressed when GVS was applied at ISI = 40 and 130ms before TMS. With the anode right/cathode left configuration, no significant changes were observed. Changes in the MEP amplitude were then compared to changes in the ongoing EMG when GVS was applied alone. Only the decrease in MEP amplitude at ISI = 40ms occurred without change in the ongoing EMG, suggesting that modulation occurred at a premotoneuronal level. We further investigated whether vestibular modulation could occur at the motor cortex level by assessing changes in the direct corticospinal pathways using the short-latency facilitation of the SOL Hoffmann reflex (H-reflex) by TMS. None of the observed modulation occurred at the level of motor cortex. Finally, using the long-latency facilitation of the SOL H-reflex, we were able to confirm that the suppression of MEP at ISI = 40ms occurred at a premotoneuronal level. The data indicate that vestibular signals modulate corticospinal output to SOL at both premotoneuronal and motoneuronal levels during standing.
BMJ Open, 2021
Introduction Activity-based therapy (ABT) is an important aspect of rehabilitation following trau... more Introduction Activity-based therapy (ABT) is an important aspect of rehabilitation following traumatic spinal cord injury (SCI). Unfortunately, it has never been adapted to acute care despite compelling preclinical evidence showing that it is safe and effective for promoting neurological recovery when started within days after SCI. This article provides the protocol for a study that will determine the feasibility and explore potential benefits of early ABT in the form of in-bed leg cycling initiated within 48 hours after the end of spinal surgery for SCI. Methods and analysis PROMPT-SCI (protocol for rapid onset of mobilisation in patients with traumatic SCI) is a single-site single-arm proof-of-concept trial. Forty-five patients aged 18 years or older with a severe traumatic SCI (American Spinal Injury Association Impairment Scale grade A, B or C) from C0 to L2 undergoing spinal surgery within 48 hours of the injury will be included. Participants will receive daily 30 min continuou...
Experimental Brain Research, 2021
Individuals with incomplete spinal cord injury (iSCI) show altered postural reactions leading to ... more Individuals with incomplete spinal cord injury (iSCI) show altered postural reactions leading to increased risk of falls. To investigate neural correlates underlying this deficit, we assessed the modulation pattern of the Soleus H-reflex in iSCI individuals following unexpected perturbations of a base of support. Ten men with iSCI (AIS D) and 8 age-matched controls (CTRL) stood on a force-platform randomly tilted forward or backward. The center of pressure (CoP) excursion, 95% confidence ellipse area and electromyographic (EMG) activity of the Soleus (SOL) and Tibialis Anterior (TA) muscles were analyzed. SOL H-reflex amplitude was assessed by stimulating the tibial nerve prior to and at 100, 150 and 200 ms following perturbation onset. Although SOL and TA short-latency EMG responses were comparable in both groups, long-latency EMG responses occurred later in the iSCI group for both directions: during backward tilt, a decrease in H-reflex amplitude was observed at all stimulus timings post-tilt in CTRL, but only at 200 ms in iSCI. The decrease in H-reflex amplitude was smaller in iSCI participants. During forward tilt, an increase in H-reflex amplitude was observed at 150 and 200 ms in the CTRL group, but no increase was observed in the iSCI group. Decreased and delayed SOL H-reflex amplitude modulation in the iSCI group accompanied impaired balance control as assessed clinically with the Berg Balance Scale and biomechanically through CoP displacement. Overall, delayed and reduced spinal reflex processing may contribute to impaired balance control in people with iSCI.
Spinal Cord Series and Cases, 2022
Study design Observational, cohort study. Objectives (1) Determine the feasibility and relevance ... more Study design Observational, cohort study. Objectives (1) Determine the feasibility and relevance of assessing corticospinal, sensory, and spinal pathways early after traumatic spinal cord injury (SCI) in a rehabilitation setting. (2) Validate whether electrophysiological and magnetic resonance imaging (MRI) measures taken early after SCI could identify preserved neural pathways, which could then guide therapy. Setting Intensive functional rehabilitation hospital (IFR). Methods Five individuals with traumatic SCI and eight controls were recruited. The lower extremity motor score (LEMS), electrical perceptual threshold (EPT) at the S2 dermatome, soleus (SOL) H-reflex, and motor evoked potentials (MEPs) in the tibialis anterior (TA) muscle were assessed during the stay in IFR and in the chronic stage (>6 months post-SCI). Control participants were only assessed once. Feasibility criteria included the absence of adverse events, adequate experimental session duration, and complete dat...
Motor Control, 2021
We tested the hypothesis that the ipsilateral corticospinal system, like the contralateral cortic... more We tested the hypothesis that the ipsilateral corticospinal system, like the contralateral corticospinal system, controls the threshold muscle length at which wrist muscles and the stretch reflex begin to act during holding tasks. Transcranial magnetic stimulation was applied over the right primary motor cortex in 21 healthy subjects holding a smooth or coarse block between the hands. Regardless of the lifting force, motor evoked potentials in right wrist flexors were larger for the smooth block. This result was explained based on experimental evidence that motor actions are controlled by shifting spatial stretch reflex thresholds. Thus, the ipsilateral corticospinal system is involved in threshold position control by modulating facilitatory influences of hand skin afferents on motoneurons of wrist muscles during bimanual object manipulation.
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Papers by Dorothy Barthélemy