Direction-dependent differences in the quality and quantity of horizontal reaching in people after stroke.

Arm reaching is often impaired in individuals with stroke. Nonetheless, how aiming directions influence reaching performance and how such differences change with motor recovery over time remain unclear. Here, we elucidated kinematic parameters of reaching toward various directions in people with poststroke hemiparesis in the subacute phase. A total of 13 and 15 participants with mild and moderate-to-severe hemiparesis, respectively, performed horizontal reaching in eight directions with their more-affected and less-affected sides using an exoskeleton robotic device at the time of admission to and discharge from the rehabilitation ward of the hospital. The movement time, path length, and number of velocity peaks were computed for the mild group (participants able to reach toward all eight directions). In addition, the total amount of displacement (i.e., movement quantity) toward two simplified directions (mediolateral or anteroposterior) was evaluated for the moderate-to-severe group (participants who showed difficulty in completing the reaching task). Motor recovery was evaluated using the Fugl-Meyer assessment. The mild group showed worse values of movement parameters during reaching in the anteroposterior direction, irrespective of the side of the arm or motor recovery achieved. The moderate-to-severe group exhibited less movement toward the anteroposterior direction than toward the mediolateral direction at admission; however, this direction-dependent bias in movement quantity decreased, with the movement expanding toward the anteroposterior direction with motor recovery at discharge. These results suggest that direction-dependent differences in the quality and quantity of reaching performance exist in people after stroke, regardless of the presence or severity of hemiparesis. This highlights the need to consider the task work area when designing rehabilitative training.NEW & NOTEWORTHY Arm reaching, a fundamental function required for the upper extremities, is often impaired after stroke due to muscle weakness and abnormal synergies. Nonetheless, how aiming directions influence performance remains unclear. Here, we report that direction-dependent differences in the quality and quantity of reaching performance exist, surprisingly regardless of the presence or severity of hemiparesis. This result highlights the need to consider the task work area when designing rehabilitative training.

Reliability of the thumb localizing test and its validity against quantitative measures with a robotic device in patients with hemiparetic stroke.

OBJECTIVES: To examine the inter-rater reliability of the thumb localizing test (TLT) and its validity against quantitative measures of proprioception. METHODS: The TLT was assessed by two raters in a standardized manner in 40 individuals with hemiparetic stroke. Inter-rater reliability was examined with weighted Kappa. For the quantitative measures, a bimanual matching task in a planar robotic device was performed. Without vision, each participant moved the unaffected hand to the perceived mirrored location of the affected hand, which was passively moved by the robot. Three measures were taken after 54 trials: Variability, trial-to-trial variability of the mirrored-matched locations; Area, the ratio of the area enclosed by the active hand relative to the passive hand; and Shift, systematic shifts between the passive and active hands. The correlation between the TLT and each robotic measure was examined with Spearman's rank correlation coefficient. RESULTS: The overall weighted kappa of the TLT was 0.84 (P<0.001). The TLT correlated highly with Area (r = -0.71, P<0.001) and moderately with Variability (r = 0.40, P = 0.011). No significant correlation was found between the TLT and Shift. CONCLUSIONS: The TLT had a high inter-rater reliability, and was validated against quantitative measures of proprioception reflecting the perceived area of movement and variability of the limb location.

Magnesium Suppresses Defects in the Formation of 70S Ribosomes as Well as in Sporulation Caused by Lack of Several Individual Ribosomal Proteins.

Individually, the ribosomal proteins L1, L23, L36, and S6 are not essential for cell proliferation of Bacillus subtilis, but the absence of any one of these ribosomal proteins causes a defect in the formation of the 70S ribosomes and a reduced growth rate. In mutant strains individually lacking these ribosomal proteins, the cellular Mg2+ content was significantly reduced. The deletion of YhdP, an exporter of Mg2+, and overexpression of MgtE, the main importer of Mg2+, increased the cellular Mg2+ content and restored the formation of 70S ribosomes in these mutants. The increase in the cellular Mg2+ content improved the growth rate and the cellular translational activity of the ΔrplA (L1) and the ΔrplW (L23) mutants but did not restore those of the ΔrpmJ (L36) and the ΔrpsF (S6) mutants. The lack of L1 caused a decrease in the production of Spo0A, the master regulator of sporulation, resulting in a decreased sporulation frequency. However, deletion of yhdP and overexpression of mgtE increased the production of Spo0A and partially restored the sporulation frequency in the ΔrplA (L1) mutant. These results indicate that Mg2+ can partly complement the function of several ribosomal proteins, probably by stabilizing the conformation of the ribosome.IMPORTANCE We previously reported that an increase in cellular Mg2+ content can suppress defects in 70S ribosome formation and growth rate caused by the absence of ribosomal protein L34. In the present study, we demonstrated that, even in mutants lacking individual ribosomal proteins other than L34 (L1, L23, L36, and S6), an increase in the cellular Mg2+ content could restore 70S ribosome formation. Moreover, the defect in sporulation caused by the absence of L1 was also suppressed by an increase in the cellular Mg2+ content. These findings indicate that at least part of the function of these ribosomal proteins can be complemented by Mg2+, which is essential for all living cells.

Robotic Assessment of Upper Limb Function after Proximal Humeral Fracture: Personal Experience as A Patient and Occupational Therapist.

Robotics is an emerging field in rehabilitation medicine. Robots have the potential to complement traditional clinical assessments because they can measure functions more precisely and quantitatively than current clinical assessments. We present a patient with a proximal humeral fracture whose recovery process was evaluated with an exoskeleton robotic device. The patient, a 34-year-old woman, suffered a left proximal humeral fracture while snowboarding. She is an occupational therapist and is the first author of this study. With conservative therapy, fracture union was seen on X-ray at 6 weeks post-injury. At that time, the patient was permitted to move her left upper limb actively within the tolerance of pain. We assessed the function of the injured upper limb at 6, 7, and 12 weeks post-injury with the KINARM exoskeleton robotic device and with conventional clinical measures. The active range of motion and the muscle strength of the left shoulder improved over time. Using robotic assessment, the precise movement profiles, position sense, and functional ability of both arms were quantified and also showed progressive improvement over time. Assessment with a robotic device of the recovery process after proximal humeral fracture allowed quantification of functional impairments that could not be felt subjectively nor identified with conventional clinical assessments.

Clinical usefulness and validity of robotic measures of reaching movement in hemiparetic stroke patients.

BACKGROUND: Various robotic technologies have been developed recently for objective and quantitative assessment of movement. Among them, robotic measures derived from a reaching task in the KINARM Exoskeleton device are characterized by their potential to reveal underlying motor control in reaching movements. The aim of this study was to examine the clinical usefulness and validity of these robot-derived measures in hemiparetic stroke patients. METHODS: Fifty-six participants with a hemiparetic arm due to chronic stroke were enrolled. The robotic assessment was performed using the Visually Guided Reaching (VGR) task in the KINARM Exoskeleton, which allows free arm movements in the horizontal plane. Twelve parameters were derived based on motor control theory. The following clinical assessments were also administered: the proximal upper limb section in the Fugl-Meyer Assessment (FMA-UE(A)), the proximal upper limb part in the Stroke Impairment Assessment Set (SIAS-KM), the Modified Ashworth Scale for the affected elbow flexor muscles (MAS elbow), and seven proximal upper limb tasks in the Wolf Motor Function Test (WMFT). To explore which robotic measures represent deficits of motor control in the affected arm, the VGR parameters in the paretic arm were compared with those in the non-paretic arm using the Wilcoxon signed rank test. Then, to explore which VGR parameters were related to overall motor control regardless of the paresis, correlations between the paretic and non-paretic arms were examined. Finally, to investigate the relationships between the robotic measures and the clinical scales, correlations between the VGR parameters and clinical scales were investigated. Spearman's rank correlation coefficients were used for all correlational analyses. RESULTS: Eleven VGR parameters on the paretic side were significantly different from those on the non-paretic side with large effect sizes (|effect size| = 0.76-0.87). Ten VGR parameters correlated significantly with FMA-UE(A) (|r| = 0.32-0.60). Eight VGR parameters also showed significant correlations with SIAS-KM (|r| = 0.42-0.49), MAS elbow (|r| = 0.44-0.48), and the Functional Ability Scale of the WMFT (|r| = 0.52-0.64). CONCLUSIONS: The robot-derived measures could successfully differentiate between the paretic arm and the non-paretic arm and were valid in comparison to the well-established clinical scales.