Extensors respond faster than flexors for the MCP joints even under the loss of the corticospinal system

Damage in the corticospinal system following stroke produces imbalance between flexors and extensors in the upper extremity including the fingers, eventually leading to flexion-favored postures. The substitution of the reticospinal tract for the damaged corticospinal tract is known to excessively activate flexors of the fingers while the fingers are voluntarily being extended. Here, we questioned whether the cortical source or/and neural pathways of the flexors and extensors of the fingers are coupled and what factor of impairment influences finger movement. In this study, a total of 7 male participants with hemiplegic stroke conducted isometric flexion and extension at the MCP joints in response to auditory tones. We measured activation and de-activation delays of the flexor and extensor of the MCP joints on the paretic side, as well as, force generation and co-contraction between the flexor and extensor. All participants generated greater torque in the direction of flexion (p=0.017). Regarding co-contraction, coupled activation of the extensor is also made during flexion in the similar way to coupled activation of the flexor made during extension. As opposite to our expectation, we observed that during extension, the extensor showed marginally significantly faster activation (p=0.66) while it showed faster de-activation (p=0.038), in comparison to activation and de-activation of the flexor during flexion. But movement smoothness was not affected by those factors. Our results imply that the cortical source and neural pathway for the extensors of the MCP joints are not coupled with those for the flexors of the MCP joints and extensor weakness mainly contributes to the asymmetry between flexors and extensors.

Extensors respond faster than flexors for the MCP joints even under the loss of the corticospinal system

Damage in the corticospinal system following stroke produces imbalance between flexors and extensors in the upper extremity including the fingers, eventually leading to flexion-favored postures. The substitution of the reticospinal tract for the damaged corticospinal tract is known to excessively activate flexors of the fingers while the fingers are voluntarily being extended. Here, we questioned whether the cortical source or/and neural pathways of the flexors and extensors of the fingers are coupled and what factor of impairment influences finger movement. In this study, a total of 7 male participants with hemiplegic stroke conducted isometric flexion and extension at the MCP joints in response to auditory tones. We measured activation and de-activation delays of the flexor and extensor of the MCP joints on the paretic side, as well as, force generation and co-contraction between the flexor and extensor. All participants generated greater torque in the direction of flexion (p=0.017). Regarding co-contraction, coupled activation of the extensor is also made during flexion in the similar way to coupled activation of the flexor made during extension. As opposite to our expectation, we observed that during extension, the extensor showed marginally significantly faster activation (p=0.66) while it showed faster de-activation (p=0.038), in comparison to activation and de-activation of the flexor during flexion. But movement smoothness was not affected by those factors. Our results imply that the cortical source and neural pathway for the extensors of the MCP joints are not coupled with those for the flexors of the MCP joints and extensor weakness mainly contributes to the asymmetry between flexors and extensors.

Physical Therapy and Rehabilitation Ideas for Inspiratory Muscle Training in Patients With Subacute Stroke

Objectives: This study aimed to elucidate the outcome of an Inspiratory Muscle Training (IMT) rehabilitation intervention on the lung function, functional mobilization, balance, and peripheral muscle strength of the paretic side in patients with subacute stroke. Methods: This double-blind, randomized controlled trial study was conducted on patients with stable subacute stroke. For 8 weeks, the intervention group (n=16) received 40% intensity IMT while the control group (n=16) received 10% intensity IMT. We assessed the patients’ lung function (spirometer) before and after the intervention, as well as their pulmonary muscle strength (micro-respiratory pressure meter [RPM]), quadriceps strength (handheld dynamometer), grip strength (Jamar), walking speed (10-m walk test), balance (Berg Balance Scale [BBS]), and functional mobilization (sit-to-stand test). Results: There were significant differences between the intervention group and the control group after IMT for forced vital capacity (FVC)% (P<0.01; d=3.20), forced expiratory volume in the first second (FEV1)/FVC (P<0.001; d=2.55), FEV1% (P<0.001; d=5.10), walking speed (P<0.05; d=1.62), hand grip (P<0.001; d=2.45), quadriceps strength (P<0.001; d=4.18), functional mobilization (P<0.01; d=2.41), and maximal inspiratory mouth pressure (P<0.001; d=1.62), but no significant changes were seen in balance (P=0.304; d=0.57). Discussion: IMT improved lung function, functional mobilization, handgrip strength, and quadriceps strength on the paretic side of subacute stroke patients and is expected to improve functional status and allow the patient to participate in social activities. IMT exercise can be included in the rehabilitation program for subacute stroke patients.

Trunk Muscle Activation Patterns During Standing Turns in Patients With Stroke: An Electromyographic Analysis

Recent evidence indicates that turning difficulty may correlate with trunk control; however, surface electromyography has not been used to explore trunk muscle activity during turning after stroke. This study investigated trunk muscle activation patterns during standing turns in healthy controls (HCs) and patients with stroke with turning difficulty (TD) and no TD (NTD). The participants with stroke were divided into two groups according to the 180° turning duration and number of steps to determine the presence of TD. The activation patterns of the bilateral external oblique and erector spinae muscles of all the participants were recorded during 90° standing turns. A total of 14 HCs, 14 patients with TD, and 14 patients with NTD were recruited. The duration and number of steps in the turning of the TD group were greater than those of the HCs, independent of the turning direction. However, the NTD group had a significantly longer turning duration than did the HC group only toward the paretic side. Their performance was similar when turning toward the non-paretic side; this result is consistent with electromyographic findings. Both TD and NTD groups demonstrated increased amplitudes of trunk muscles compared with the HC groups. Their trunk muscles failed to maintain consistent amplitudes during the entire movement of standing turns in the direction that they required more time or steps to turn toward (i.e., turning in either direction for the TD group and turning toward the paretic side for the NTD group). Patients with stroke had augmented activation of trunk muscles during turning. When patients with TD turned toward either direction and when patients with NTD turned toward the paretic side, the flexible adaptations and selective actions of trunk muscles observed in the HCs were absent. Such distinct activation patterns during turning may contribute to poor turning performance and elevate the risk of falling. Our findings provide insights into the contribution and importance of trunk muscles during turning and the association with TD after stroke. These findings may help guide the development of more effective rehabilitation therapies that target specific muscles for those with TD.

Wrist Actimetry Biomarker Development of Paretic Upper Limb Use in Post Stroke Patients for Ecological Monitoring.

Background In post-stroke patients it is unclear which wrist actimetry biomarkers to use to estimate the degree of upper limb hemiparesis. The objective of this study was to develop a general and objective framework for monitoring hemiparetic patients in their home environment via different biomarkers based on 7 days of actimetry data. A secondary objective was to use all of these biomarkers to better understand the mechanism for potential non-use of the paretic upper limb. Methods Accelerometers were worn continuously for a period of 7 days on both wrists of 10 post-stroke hemiparetic patients as well as 6 healthy subjects. Various wrist actimetry biomarkers were calculated, including the Jerk ratio 50 (JR50, cumulative probability that the Jerk Ratio is between 0 and 0.5), absolute and relative amounts of functional use of movements of the upper limbs (FuncUse and FuncUseR) and absolute and relative velocities of the upper limbs during functional use (VUL and VULR). For each biomarker, the values of stroke and healthy groups were compared. The correlations between all the biomarkers were studied. Results We studied 10 participants with mild-to-moderate chronic hemiparesis and 6 healthy control participants. FuncUse and VUL of the paretic upper limb of stroke patients were significantly lower than in the non-dominant upper limb of healthy subjects. Similarly, FuncUseR (paretic/non-paretic vs non-dominant/dominant), JR and VULR are significantly lower in stroke patients than in healthy subjects. FuncUseR, VULR and JR50 seem to be complementary biomarkers for monitoring patient strokes. Conclusion The stroke patients do not seem to compensate for the decrease in functional movement on the paretic side by an increase on the non-paretic side. The speed of execution of functional movements on the paretic side could be the limiting factor to a normal use of the paretic upper limb. A thorough clinical study is needed to identify the limiting factors. In conclusion, this study for the first time has shown actimetry is a robust and non-obtrusive lightweight technology for continuously acquiring objective upper limb data of paretic arm use/ non-use over an extended period in a home environment for monitoring stroke patients.

Changes in Muscle Activity with Assistance Level During Exoskeletal Gait in Acute Stroke

BackgroundThe level of assistance provided to the user is an important decision in rehabilitation training using robotic devices. Both fully assistive and assist-as-needed paradigms have shown benefits in functional outcomes in healthy individuals and users with chronic stroke and spinal cord injury. The effect of assistance level on muscle activity and kinematic gait parameters has not yet been directly examined during overground exoskeletal gait in a stroke population. Furthermore, it is not clear whether an assist-as-needed approach could elicit increased voluntary activity in individuals in the acute stages of stroke. The aim of this study was to examine the effect of assistance level on muscle activity and kinematic parameters during exoskeleton gait in individuals in the acute stage of stroke care.MethodsNine individuals in the acute stage of post-stroke care performed walking tasks in the EKSO GTTM exoskeleton using both maximal assistance and adaptive assistance control paradigms. Temporal gait parameters and muscle activity were recorded using accelerometers and surface EMG on the lower limb muscles.ResultsShorter swing times and longer double support times were observed on the non-paretic side during adaptive assist mode than with maximum assist mode (p<0.0065). No significant effect of exoskeleton mode was observed on the remaining temporal gait parameters. On the paretic side, proximal lower limb muscles (RF and ST) and plantar-flexors (SO) (p<0.00125) exhibited greater activation in adaptive assist mode than in maximum assist mode. On the non-paretic side however, the lower limb distal muscles (TA and SO) displayed greater activity during maximum assist mode than adaptive assist mode (p<0.00125). ConclusionsThe level of assistance provided by an exoskeleton in the acute stages of stroke care is an important clinical decision. The results indicate that an adaptive or assist-as-needed approach elicits higher levels of activation in muscles acting around the knee joint and plantar-flexors on the paretic side than a maximal, fixed assistance paradigm, in the acute stage post-stroke. Increased activity around the ankle joint during maximum assistance mode was also noted. Improved understanding of the effect of assistance level can help inform future control paradigms for exoskeleton gait in acute stroke.

Ultrasound Evaluation of the Rectus Femoris for Sarcopenia in Patients with Early Subacute Stroke

We investigated the ultrasound characteristics of the rectus femoris for sarcopenia detected by dual-energy X-ray absorptiometry (DEXA) in the early subacute stroke phase. Physical features (age, sex, body mass index, and circumference of thigh) and performances (modified Barthel index in Korean, functional ambulation categories, and mini-mental state examination in Korean) were measured. The thickness of the fat layer, the thickness of the rectus femoris (TRF), echo intensity (EI), EI to TRF ratio, and strain ratio of elastography (SRE) were measured by ultrasound in 30 patients with first-ever stroke (male: n = 20). Appendicular lean body mass was measured by DEXA. Sarcopenia was defined according to the Foundation for the National Institutes of Health Sarcopenia Project. In total, 14 patients were in the sarcopenia group, and 16 were in the non-sarcopenia group. Clinical characteristics were similar between the two groups. In the sarcopenia group, TRF was significantly decreased in the paretic (p < 0.026) and non-paretic sides (p < 0.01), and the EI to TRF ratio on the paretic side was significantly increased (p < 0.049). Multivariate binary logistic regression showed that TRF on the non-paretic side was independently and significantly associated with sarcopenia (OR = 0.68, 95% CI: 0.463–0.999). The EI and SRE were not significant between the two groups. In the early subacute stroke phase, TRF on the non-paretic side is a key factor for quantitative evaluation of sarcopenia, and the EI to TRF ratio on the paretic side is also a meaningful qualitative evaluation of sarcopenia.

Effect of residual lower-extremity function on strategies and execution time for raising and lowering trousers in patients with hemiparetic stroke: a cross-sectional study

Background/aims There are no established methods for patients with hemiparetic stroke to practice the raising and lowering of trousers. The aim of this study was to investigate the use of different strategies by patients with hemiparetic stroke for lowering and raising trousers by using the non-paretic upper limb in the standing position, based on residual motor function in the paretic lower limb. Methods A total of 28 patients with hemiparetic stroke were included in the study (n=10, 12, and 6 with lower-limb Brunnstrom stages III, IV and V respectively). Endpoints were execution time and frequency of changing the manipulation region. Results Lower-limb Brunnstrom stages III, IV and V were associated with execution times of 24.1 ± 11.1, 18.1 ± 6.5 and 16.9 ± 9.6 seconds respectively, and the mean frequency of manipulation of trousers on the posterior paretic side was significantly lower than those of the anterior paretic, anterior non-paretic, and posterior non-paretic sides in all patients (P<0.05). Conclusions Motor function of the paretic lower limb did not affect the strategies used for lowering and raising trousers with the non-paretic upper limb. Manipulation of trousers on the posterior paretic side was especially difficult.