Doris Broetz

Brain-machine interface in chronic stroke rehabilitation: a controlled study.

Chronic stroke patients with severe hand weakness respond poorly to rehabilitation efforts. Here, we evaluated efficacy of daily brain–machine interface (BMI) training to increase the hypothesized beneficial effects of physiotherapy alone in patients with severe paresis in a double‐blind sham‐controlled design proof of concept study.

Combination of Brain-Computer Interface Training and Goal-Directed Physical Therapy in Chronic Stroke: A Case Report

Background. There is no accepted and efficient rehabilitation strategy to reduce focal impairments for patients with chronic stroke who lack residual movements. Methods . A 67-year-old hemiplegic patient with no active finger extension was trained with a brain—computer interface (BCI) combined with a specific daily life—oriented physiotherapy. The BCI used electrical brain activity (EEG) and magnetic brain activity (MEG) to drive an orthosis and a robot affixed to the patient’s affected upper extremity, which enabled him to move the paralyzed arm and hand driven by voluntary modulation of μ-rhythm activity. In addition, the patient practiced goal-directed physiotherapy training. Over 1 year, he completed 3 training blocks. Arm motor function, gait capacities (using Fugl-Meyer Assessment, Wolf Motor Function Test, Modified Ashworth Scale, 10-m walk speed, and goal attainment score), and brain reorganization (functional MRI, MEG) were repeatedly assessed. Results. The ability of hand and arm movements as well as speed and safety of gait improved significantly (mean 46.6%). Improvement of motor function was associated with increased μ-oscillations in the ipsilesional motor cortex. Conclusion. This proof-of-principle study suggests that the combination of BCI training with goal-directed, active physical therapy may improve the motor abilities of chronic stroke patients despite apparent initial paralysis.

Radicular and nonradicular back pain in Parkinson's disease: A controlled study

Postural abnormalities and increased muscle tone in Parkinsons disease (PD) may cause back pain. In this controlled study, we analyzed features of back pain in PD patients. The prevalence of back pain was 74% in PD patients (n = 101) when compared with 27% in control patients (n = 132; P < 0.0001, fishers exact test), but did not correlate with disease severity or duration. The mean back pain intensity (visual analog scale of 0–10) was 4.3 for PD patients, and 1.3 for controls. Both radicular and nonradicular types of back pain were more frequent, and back pain caused more impairment in PD patients. However, it is noteworthy that the PD patients in our study did not receive more pain medication than control patients. This suggests that back pain in PD patients is often neglected and insufficiently treated. Our results argue for the routine evaluation of back pain in every patient suffering from PD.

Posterior thalamic hemorrhage induces “pusher syndrome”

Background: Recent findings argue for a pathway in humans for sensing the orientation of gravity and controlling upright body posture, separate from the one for orientation perception of the visual world. Stroke patients with contraversive pushing were shown to experience their body as oriented upright when actually tilted about 20° to the ipsilesional side, in spite of normal visual-vestibular functioning. A recent study suggested the involvement of posterolateral thalamus typically associated with the disorder. Objective: To evaluate the relationship between pushing behavior and thalamic function. Methods: Over a 3-year period the authors prospectively investigated 40 patients with left- or right-sided thalamic strokes. Results: Twenty-eight percent showed contraversive pushing. The authors found a strong relationship between etiology, vascular territory, lesion size, and neurologic disorders associated with contraversive pushing. Pusher patients had larger lesions that typically were caused by hemorrhage (vs infarcts) located in the posterior thalamus (vs anterior thalamic lesions in those patients without pushing behavior). A paresis of the contralesional extremities was more frequent and more severe in pusher patients. Further, these patients showed more additional spatial neglect with right thalamic lesions, while they tended to be more aphasic with left thalamic lesions. Conclusions: Posterior thalamus seems to be fundamentally involved in our control of upright body posture. Higher pressure, swelling, and other secondary pathologic processes associated with posterior thalamic hemorrhage (vs thalamic infarction) may provoke contraversive pushing in combination with additional neurologic symptoms.

Prognosis of contraversive pushing

Stroke patients with ‘pusher syndrome’ actively push away from the non-hemiparetic side leading to a loss of postural balance and falling towards the paralysed side. The behaviour is due to an altered perception of the bodys orientation in relation to gravity. Here, we studied the prognosis of the disorder. Twelve pusher patients first investigated immediately after the stroke were re-examined 6 months later. Pusher symptoms had nearly completely recovered. The aim for physiotherapy of patients with contraversive pushing thus is to shorten the period of necessary treatment and enable earlier discharge from residential care.

Cortex integrity relevance in muscle synergies in severe chronic stroke.

Background: Recent experimental evidence has indicated that the motor system coordinates muscle activations through a linear combination of muscle synergies that are specified at the spinal or brainstem networks level. After stroke upper limb impairment is characterized by abnormal patterns of muscle activations or synergies. Objective: This study aimed at characterizing the muscle synergies in severely affected chronic stroke patients. Furthermore, the influence of integrity of the sensorimotor cortex on synergy modularity and its relation with motor impairment was evaluated. Methods: Surface electromyography from 33 severely impaired chronic stroke patients was recorded during 6 bilateral movements. Muscle synergies were extracted and synergy patterns were correlated with motor impairment scales. Results: Muscle synergies extracted revealed different physiological patterns dependent on the preservation of the sensorimotor cortex. Patients without intact sensorimotor cortex showed a high preservation of muscle synergies. On the contrary, patients with intact sensorimotor cortex showed poorer muscle synergies preservation and an increase in new generated synergies. Furthermore, the preservation of muscle synergies correlated positively with hand functionality in patients with intact sensorimotor cortex and subcortical lesions only. Conclusion: Our results indicate that severely paralyzed chronic stroke patient with intact sensorimotor cortex might sculpt new synergy patterns as a response to maladaptive compensatory strategies.

A hybrid brain-machine interface based on EEG and EMG activity for the motor rehabilitation of stroke patients

Including supplementary information from the brain or other body parts in the control of brain-machine interfaces (BMIs) has been recently proposed and investigated. Such enriched interfaces are referred to as hybrid BMIs (hBMIs) and have been proven to be more robust and accurate than regular BMIs for assistive and rehabilitative applications. Electromyographic (EMG) activity is one of the most widely utilized biosignals in hBMIs, as it provides a quite direct measurement of the motion intention of the user. Whereas most of the existing non-invasive EEG-EMG-hBMIs have only been subjected to offline testings or are limited to one degree of freedom (DoF), we present an EEG-EMG-hBMI that allows the simultaneous control of 7-DoFs of the upper limb with a robotic exoskeleton. Moreover, it establishes a biologically-inspired hierarchical control flow, requiring the active participation of central and peripheral structures of the nervous system. Contingent visual and proprioceptive feedback about the users EEG and EMG activity is provided in the form of velocity modulation during functional task training. We believe that training with this closed-loop system may facilitate functional neuroplastic processes and eventually elicit a joint brain and muscle motor rehabilitation. Its usability is validated during a real-time operation session in a healthy participant and a chronic stroke patient, showing encouraging results for its application to a clinical rehabilitation scenario.

A new hand assessment instrument for severely affected stroke patients

BACKGROUND Standard assessment instruments cannot differentiate patients with minimal residual hand function after stroke. As a result, changes in motor recovery are difficult to document using currently-available tests. In a controlled study with chronic stroke patients without residual finger extension, a new hand function test has been developed. This instrument, called Broetz Hand Test (BzH), allows to assess small variations in hand function in severely paralyzed stoke patients. The instrument is easy to use, and was developed using principles of motor learning and behavioral assessment. METHODS The instrument consists of seven daily life-oriented tasks, each of which asks for movement of the paralyzed hand. BzH of 20 patients after stroke was evaluated before and after a behavioral physiotherapy treatment. Sensitivity, inter-observer reliability, test-retest reliability and construct validity was calculated. RESULTS Two-tailed paired-samples t-test before and after treatment demonstrated sufficient sensitivity. Mean agreement between the raters resulted in an excellent interrater-reliability. Test-retest reliability between the pre- and post-treatment scores was 0.9. The correlation between BzH and standard test scores was statistically significant and demonstrated sufficient validity. CONCLUSION The BzH is a valid and reliable tool to assess changes in hand function in severely paralyzed patients after stroke.

Residual upper arm motor function primes innervation of paretic forearm muscles in chronic stroke after Brain-Machine Interface (BMI) training

Background Abnormal upper arm-forearm muscle synergies after stroke are poorly understood. We investigated whether upper arm function primes paralyzed forearm muscles in chronic stroke patients after Brain-Machine Interface (BMI)-based rehabilitation. Shaping upper arm-forearm muscle synergies may support individualized motor rehabilitation strategies. Methods Thirty-two chronic stroke patients with no active finger extensions were randomly assigned to experimental or sham groups and underwent daily BMI training followed by physiotherapy during four weeks. BMI sessions included desynchronization of ipsilesional brain activity and a robotic orthosis to move the paretic limb (experimental group, n = 16). In the sham group (n = 16) orthosis movements were random. Motor function was evaluated with electromyography (EMG) of forearm extensors, and upper arm and hand Fugl-Meyer assessment (FMA) scores. Patients performed distinct upper arm (e.g., shoulder flexion) and hand movements (finger extensions). Forearm EMG activity significantly higher during upper arm movements as compared to finger extensions was considered facilitation of forearm EMG activity. Intraclass correlation coefficient (ICC) was used to test inter-session reliability of facilitation of forearm EMG activity. Results Facilitation of forearm EMG activity ICC ranges from 0.52 to 0.83, indicating fair to high reliability before intervention in both limbs. Facilitation of forearm muscles is higher in the paretic as compared to the healthy limb (p<0.001). Upper arm FMA scores predict facilitation of forearm muscles after intervention in both groups (significant correlations ranged from R = 0.752, p = 0.002 to R = 0.779, p = 0.001), but only in the experimental group upper arm FMA scores predict changes in facilitation of forearm muscles after intervention (R = 0.709, p = 0.002; R = 0.827, p<0.001). Conclusions Residual upper arm motor function primes recruitment of paralyzed forearm muscles in chronic stroke patients and predicts changes in their recruitment after BMI training. This study suggests that changes in upper arm-forearm synergies contribute to stroke motor recovery, and provides candidacy guidelines for similar BMI-based clinical practice.

On “A four-week, task-specific neuroprosthesis program…” Dunning K, et al. Phys Ther. 2008;88:397–405.

We regard this report1 as very valuable as it describes the use of a task-specific neuroprosthesis program in a patient characterized as severely impaired without any active residual finger and hand movements. Those patients without residual finger and hand movements usually are not included in studies dealing with rehabilitation after stroke because of their negative prognosis. Fortunately, Dunning et al present a therapeutic approach that was successful for a patient with such impairment. There is one point …