Effects of a single mental chronometry training session in subacute stroke patients - a randomized controlled trial.

BACKGROUND: Motor imagery training might be helpful in stroke rehabilitation. This study explored if a single session of motor imagery (MI) training induces performance changes in mental chronometry (MC), motor execution, or changes of motor excitability. METHODS: Subacute stroke patients (n = 33) participated in two training sessions. The order was randomized. One training consisted of a mental chronometry task, the other training was a hand identification task, each lasting 30 min. Before and after the training session, the Box and Block Test (BBT) was fully executed and also performed as a mental version which served as a measure of MC. A subgroup analysis based on the presence of sensory deficits was performed. Patients were allocated to three groups (no sensory deficits, moderate sensory deficits, severe sensory deficits). Motor excitability was measured by transcranial magnetic stimulation (TMS) pre and post training. Amplitudes of motor evoked potentials at rest and during pre-innervation as well as the duration of cortical silent period were measured in the affected and the non-affected hand. RESULTS: Pre-post differences of MC showed an improved MC after the MI training, whereas MC was worse after the hand identification training. Motor execution of the BBT was significantly improved after mental chronometry training but not after hand identification task training. Patients with severe sensory deficits performed significantly inferior in BBT execution and MC abilities prior to the training session compared to patients without sensory deficits or with moderate sensory deficits. However, pre-post differences of MC were similar in the 3 groups. TMS results were not different between pre and post training but showed significant differences between affected and unaffected side. CONCLUSION: Even a single training session can modulate MC abilities and BBT motor execution in a task-specific way. Severe sensory deficits are associated with poorer motor performance and poorer MC ability, but do not have a negative impact on training-associated changes of mental chronometry. Studies with longer treatment periods should explore if the observed changes can further be expanded. TRIAL REGISTRATION: DRKS, DRKS00020355, registered March 9th, 2020, retrospectively registered.

Using an upper extremity exoskeleton for semi-autonomous exercise during inpatient neurological rehabilitation- a pilot study.

BACKGROUND: Motor deficits are the most common symptoms after stroke. There is some evidence that intensity and amount of exercises influence the degree of improvement of functions within the first 6 months after the injury. The purpose of this pilot study was to evaluate the feasibility and acceptance of semi-autonomous exercises with an upper extremity exoskeleton in addition to an inpatient rehabilitation program. In addition, changes of motor functions were examined. METHODS: Ten stroke patients with a severe upper extremity paresis were included. They were offered to perform a semi-autonomous training with a gravity-supported, computer-enhanced device (Armeo®Spring, Hocoma AG) six times per week for 4 weeks. Feasibility was evaluated by weekly structured interviews with patients and supervisors. Motor functions were assessed before and after the training period using the Wolf Motor Function Test (WMFT). The Wilcoxon Signed Rank Test was used for assessing pre-post differences. The Pearson correlation co-efficient was used for correlating the number of completed sessions with the change in motor function. Acceptance of the device and the level of satisfaction with the training were determined by a questionnaire based on visual analogue scales. RESULTS: Neither patients nor supervisors reported side effects. However, one patient had to be excluded from analysis because of transportation difficulties from the ward to the treatment facility. Therefore, analysis was based on nine patients. On average, 13.2 (55%) sessions were realized. WMFT results showed significant improvements of proximal arm functions. The number of sessions correlated with the degree of shoulder force improvement. Patients rated the exercises to be motivating, and enjoyable and would continue using the Armeo®Spring at home if they had the opportunity. CONCLUSION: Using an upper extremity exoskeleton for semi-autonomous training in an inpatient setting is feasible without side effects and is positively rated by the patients. It might further support the recovery of upper extremity function. TRIAL REGISTRATION: The trial was retrospectively registered. Registration number ISRCTN42633681 .

Reliability, validity, and clinical feasibility of a rapid and objective assessment of post-stroke deficits in hand proprioception.

BACKGROUND: Proprioceptive function can be affected after neurological injuries such as stroke. Severe and persistent proprioceptive impairments may be associated with a poor functional recovery after stroke. To better understand their role in the recovery process, and to improve diagnostics, prognostics, and the design of therapeutic interventions, it is essential to quantify proprioceptive deficits accurately and sensitively. However, current clinical assessments lack sensitivity due to ordinal scales and suffer from poor reliability and ceiling effects. Robotic technology offers new possibilities to address some of these limitations. Nevertheless, it is important to investigate the psychometric and clinimetric properties of technology-assisted assessments. METHODS: We present an automated robot-assisted assessment of proprioception at the level of the metacarpophalangeal joint, and evaluate its reliability, validity, and clinical feasibility in a study with 23 participants with stroke and an age-matched group of 29 neurologically intact controls. The assessment uses a two-alternative forced choice paradigm and an adaptive sampling procedure to identify objectively the difference threshold of angular joint position. RESULTS: Results revealed a good reliability (ICC(2,1) = 0.73) for assessing proprioception of the impaired hand of participants with stroke. Assessments showed similar task execution characteristics (e.g., number of trials and duration per trial) between participants with stroke and controls and a short administration time of approximately 12 min. A difference in proprioceptive function could be found between participants with a right hemisphere stroke and control subjects (p<0.001). Furthermore, we observed larger proprioceptive deficits in participants with a right hemisphere stroke compared to a left hemisphere stroke (p=0.028), despite the exclusion of participants with neglect. No meaningful correlation could be established with clinical scales for different modalities of somatosensation. We hypothesize that this is due to their low resolution and ceiling effects. CONCLUSIONS: This study has demonstrated the assessment's applicability in the impaired population and promising integration into clinical routine. In conclusion, the proposed assessment has the potential to become a powerful tool to investigate proprioceptive deficits in longitudinal studies as well as to inform and adjust sensorimotor rehabilitation to the patient's deficits.

Motor Imagery Impairment in Postacute Stroke Patients.

Not much is known about how well stroke patients are able to perform motor imagery (MI) and which MI abilities are preserved after stroke. We therefore applied three different MI tasks (one mental chronometry task, one mental rotation task, and one EEG-based neurofeedback task) to a sample of postacute stroke patients (n = 20) and age-matched healthy controls (n = 20) for addressing the following questions: First, which of the MI tasks indicate impairment in stroke patients and are impairments restricted to the paretic side? Second, is there a relationship between MI impairment and sensory loss or paresis severity? And third, do the results of the different MI tasks converge? Significant differences between the stroke and control groups were found in all three MI tasks. However, only the mental chronometry task and EEG analysis revealed paresis side-specific effects. Moreover, sensitivity loss contributed to a performance drop in the mental rotation task. The findings indicate that although MI abilities may be impaired after stroke, most patients retain their ability for MI EEG-based neurofeedback. Interestingly, performance in the different MI measures did not strongly correlate, neither in stroke patients nor in healthy controls. We conclude that one MI measure is not sufficient to fully assess an individual's MI abilities.

Mental chronometry and mental rotation abilities in stroke patients with different degrees of sensory deficit.

BACKGROUND: Motor imagery is used for treatment of motor deficits after stroke. Clinical observations suggested that motor imagery abilities might be reduced in patients with severe sensory deficits. This study investigated the influence of somatosensory deficits on temporal (mental chronometry, MC) and spatial aspects of motor imagery abilities. METHODS: Stroke patients (n = 70; <6 months after stroke) were subdivided into 3 groups according to their somatosensory functions. Group 1 (n = 31) had no sensory deficits, group 2 (n = 27) had a mild to moderate sensory impairment and group 3 (n = 12) had severe sensory deficits. Patients and a healthy age-matched control group (n = 23) participated in a mental chronometry task (Box and Block Test, BBT) and a mental rotation task (Hand Identification Test, HIT). MC abilities were expressed as a ratio (motor execution time-motor imagery time/motor execution time). RESULTS: MC for the affected hand was significantly impaired in group 3 in comparison to stroke patients of group 1 (p = 0.006), group 2 (p = 0.005) and healthy controls (p < 0.001). For the non-affected hand MC was similar across all groups. Stroke patients had a slower BBT motor execution than healthy controls (p < 0.001), and group 1 executed the task faster than group 3 (p = 0.002). The percentage of correct responses in the HIT was similar for all groups. CONCLUSION: Severe sensory deficits impair mental chronometry abilities but have no impact on mental rotation abilities. Future studies should explore whether the presence of severe sensory deficits in stroke patients reduces the benefit from motor imagery therapy.

Temporary deafferentation evoked by cutaneous anesthesia: behavioral and electrophysiological findings in healthy subjects.

Motor function and motor excitability can be modulated by changes of somatosensory input. Here, we performed a randomized single-blind trial to investigate behavioral and neurophysiological changes during temporary deafferentation of left upper arm and forearm in 31 right-handed healthy adults. Lidocaine cream was used to anesthetize the skin from wrist to shoulder, sparing the hand. As control condition, on a different day, a neutral cream was applied to the same skin area. The sequence (first Lidocaine, then placebo or vice versa) was randomized. Behavioral measures included the Grating Orientation Task, the Von Frey hair testing and the Nine-hole-peg-test. Transcranial magnetic stimulation was used to investigate short-interval intracortical inhibition, stimulus response curves, motor evoked potential amplitudes during pre-innervation and the cortical silent period (CSP). Recordings were obtained from left first dorsal interosseous muscle and from left flexor carpi radialis muscle. During deafferentation, the threshold of touch measured at the forearm was significantly worse. Other behavioral treatment-related changes were not found. The CSP showed a significant interaction between treatment and time in first dorsal interosseous muscle. CSP duration was longer during Lidocaine application and shorter during placebo exposure. We conclude that, in healthy subjects, temporary cutaneous deafferentation of upper and lower arm may have minor effects on motor inhibition, but not on sensory or motor function for the adjacent non-anesthetized hand.