Application of digitization and visualization-based muscle strength measurement in ischemic stroke patients with motor dysfunction

Ischemic stroke stands as a prevalent neurological ailment, where a paucity of methodologies exists for the assessment of functional outcomes post-stroke. Our objective was the development of a WeChat applet for the evaluation of muscle strength and the subsequent evaluation of its validity in ischemic stroke patients experiencing motor dysfunction. The assessment encompassed Lovett and NIHSS, followed by muscle strength values (MSV) and muscle strength ratios (MSR). These metrics were then scrutinized in relation to NIHSS and Lovett, followed by examination of their interrelationships. We enrolled a cohort of 157 patients, with an average age of 65 years, consisting of 96 males and 61 females. Lovett scores in the range of 2–4 and NIHSS scores spanning from 0 to 3 were found to correspond to specific values of MSV and MSR, respectively. Upon conducting correlation analysis, we noted that both MSV and MSR exhibited significant positive correlations with Lovett scores and NIHSS. Remarkably, the correlation of MSR with Lovett scores or NIHSS surpassed that of MSV. The WeChat applet offers a means of digitization and visualization of muscle strength. It correlates well with Lovett score and NIHSS, especially MSR. This bears potential significance in guiding the rehabilitation of stroke patients.


Evaluation of Lovett muscle score
Two highly skilled neurosurgeons, who underwent specialized training and adhered to a meticulously standardized measurement protocol, conducted assessments of the patients' Lovett score, NIHSS, and muscle strength value.Patients were positioned supine and instructed to raise their arm at a 45-degree angle.Lovett scores were meticulously assigned in accordance with predefined scoring criteria, initially on the unaffected side and subsequently on the affected side.Only the value recorded on the affected side was integrated into the final analysis and reported.As elucidated in a prior study, the Lovett scale encompasses six distinct grades, each indicative of varying levels of muscle strength 24 .Within this framework, a score of 0 signifies the absence of observable voluntary muscle contraction, while a score of 5 signifies normal muscle strength, exemplified by a patient capable of overcoming resistance.

Evaluation of "upper limb movement" section of NIHSS score
The NIHSS, often employed as an early secondary outcome measure in stroke trials, yields scores spanning from 0 to 42, with higher scores signifying more pronounced neurological deficits 25 .In this context, the 'Upper Limb Movement' section of the NIHSS score was administered to assess the muscle strength of each ischemic stroke patient.The specific methodology entailed placing the patient in a supine position and instructing them to elevate their arm to a 45-degree angle.Their capacity to sustain this position for a duration of 10 s was diligently observed, with scores subsequently allocated based on predetermined criteria.Assessments were initially conducted on the unaffected side and then replicated on the affected side.Only the score originating from the affected side was integrated into the final analysis and subsequently reported.

WeChat Applet for muscle strength measurement
Following the completion of Lovett score and NIHSS assessment, patients underwent a 5-min resting period.Subsequently, upper limb muscle strength was quantified utilizing the WeChat mini-program, yielding measurements for both MSV and MSR.To commence, the assessor provided a standardized demonstration.Subsequently, with the patient in a supine position, the outer elbow of the upper limb was positioned on the force measuring surface of the dynamometer, with the back resting on the immobilizer (weighting, 300 g, dimensions: 9.5 * 9.5 * 4.5 cm, Patent No. 202011218709.0,manufactured by Guangxi Jiugaohe Intelligent Technology Co., Ltd.) (Fig. 1).The patient was then instructed to exert maximal force in abducting the upper limb on the unaffected side.Once the muscle strength values stabilized on the display screen, MSVs recorded within a 10-s interval were documented, and the mean value was subsequently calculated as the final MSV (Fig. 2).Similarly, the muscle strength of the affected-side upper limb was assessed using identical procedures.Subsequently, the patient's 'affected to unaffected upper limb' MSR was computed using the formula ((MSR [%] = MSV of the affected−side upper limp MSV of the unaffected−side upper limp × 100 ).).Only the MSV or MSR originating from the affected side was integrated into the final analysis and subsequently reported.

Ethical approval
This research received approval from the Ethics Committee of the Affiliated Hospital of Guilin Medical University, and we meticulously adhered to ethical standards throughout the study.

Statistical analysis
Continuous data were presented as mean ± standard deviation.Group comparisons were conducted using oneway analysis of variance (ANOVA), followed by Bonferroni's post hoc test to identify intergroup differences.Categorical data were expressed as percentages.The chi-squared test was employed to assess variations in gender,

Patient characteristics
Based on the aforementioned criteria for inclusion and exclusion, a total of 157 ischemic stroke patients with motor impairment were enrolled in this study (Fig. 3).Their mean age stood at 65 years, while their average height and weight were recorded as 163 cm and 64 kg, respectively.Upon classification according to Lovett score or NIHSS, it is noteworthy that there existed no statistically significant disparities in the distribution of these factors among the respective subgroups (Table 1 and Table 2; both P > 0.05).This observation underscores the conclusion that the distribution of these factors within subgroups, encompassing gender, age, height, weight, and the affected side, exerts no influence on the comparative analysis of muscle strength across distinct subgroups.

WeChat Applet for muscle strengthen measurement after grouping by Lovett muscle score
When grouped according to the Lovett score (Fig. 4A,B), the mean MSV of the affected-side upper limb exhibited the following values: 16.1 ± 7.1 Newton (N) with a 95% confidence interval (CI) ranging from 13.8 to 18.3 N for the 42 patients in grade 2; 61.

WeChat Applet for muscle strength measurement after grouping by NIHSS score
When categorized according to the 'Upper Limb Movement' section of the NIHSS (Fig. 5A,B), the mean MSV and MSR values were as follows: For 67 patients with an NIHSS score of 0: MSV was 88.0 ± 20.9 N (95% CI 78.7-97.2%)and MSR was 77.www.nature.com/scientificreports/(95% CI 13.1-20.0%).As depicted in Fig. 4, statistically significant distinctions were evident in the overall mean MSV and MSR values when grouped by NIHSS score (all P < 0.001).Bonferroni post hoc testing revealed significant differences in MSV among the NIHSS 0, 2, and 3 subgroups (all P < 0.001), while no statistically significant differences were detected between the NIHSS 1 and 2 groups (P = 0.247).Conversely, significant statistical disparities were identified across all MSR subgroups based on NIHSS scores (all P < 0.001).Upon assessment of data normality, Spearman correlation coefficient analysis was conducted.The findings underscored noteworthy correlations between both MSV and MSR with the NIHSS score, yielding correlation coefficients of 0.791 and 0.899, respectively (both P < 0.01).

Discussion
Early diagnosis and treatment of stroke are paramount for achieving favorable clinical outcomes 26   post-stroke patients.This approach has the potential to reduce reliance on patient-reported scores and evaluation data, thereby enhancing objectivity and mitigating retrospective bias.The merits and innovations of this clinical trial are delineated as follows.
Given the multitude of methods available for assessing muscle function and physical performance, even seasoned clinicians often grapple with the challenge of selecting an appropriate tool validated for older populations, particularly those who have experienced a stroke 28 .Many of the highly specialized approaches necessitate professional training and tend to consume a significant amount of time during evaluation, as exemplified by the widely employed Lovett and NIHSS scoring systems 11,24 .These factors not only encumber healthcare providers but also impose constraints on patient cooperation.Furthermore, they do not facilitate the continuous, longterm assessment of muscle strength.Simultaneously, it is imperative to acknowledge that due to variations in the methodology and the patients' condition at the time of testing, the Lovett and NIHSS scores may not consistently align with the patients' actual muscle strength 29 .As evidenced by the research findings, the comparison of MSV in the NIHSS score 1 and 2 groups did not yield statistical significance (P = 0.247).This variability can be attributed to the inherent characteristics and behavioral state of the patients undergoing the muscle strength evaluation process.On occasion, during the measurement of muscle strength, patients may have been at rest or in a transitional state upon awakening from sleep.Consequently, the Lovett score, NIHSS score and MSV may not accurately reflect the patient's true condition.To address this, we introduced the assessment of MSR.Moreover,  muscle strength measurement has exhibited substantial potential in assessing patient outcomes.Throughout the course of our research, we observed instances where some patients maintained a consistent Lovett Score level during their hospitalization, yet their MSV and MSR continued to rise.This observation suggests that within a narrow range of muscle strength fluctuations, the WeChat Applet employed for muscle strength measurement demonstrates greater sensitivity compared to Lovett score assessments.Consequently, Lovett score evaluations may not be ideal for gauging treatment efficacy in such patients.
While quantifying both MSV and MSR, we established a meaningful correspondence with Lovett and NIHSS scores, facilitating their validation and comparison.Upon analyzing the data, it is evident that both MSV and MSR exhibit commendable correlations with the Lovett and NIHSS score, with MSR demonstrating particularly strong associations.Figures 3 and 4 reveal that the SD of MSV is consistently relatively high, and there is a noticeable ' overlapping' phenomenon in the ' distribution interval of MSVs' between Lovett scores 3 and 4.This overlapping occurrence may compromise the accuracy of muscle strength assessment, underscoring the rationale behind our emphasis on MSR.In light of these considerations, we propose the utilization of MSR in conjunction with MSV for muscle strength assessment to enhance precision.In future investigations, we intend to explore the application of the 'maximum strength multiplied by duration' concept to further assess changes in patients' muscle strength.
Furthermore, owing to the absence of specialized training requirements, patients can autonomously conduct muscle strength measurements with the assistance of family members.Notably, each muscle strength measurement can be securely stored within the WeChat Applet's cloud database, forming an individualized repository.This database can be swiftly and systematically reviewed, offering valuable insights into the effectiveness of treatment.Patients also have the capability to share their data with physicians through cloud services, facilitating real-time monitoring of their condition.This, in turn, aids physicians in promptly devising personalized treatment strategies.Standardizing muscle strength assessment for healthcare professionals can be challenging, given variations in experience, skill levels, and understanding.However, the WeChat Applet for muscle strength mitigates this issue.Furthermore, using a single account, muscle strength data can be shared among healthcare providers with the patient's consent, significantly enhancing operational efficiency.Presently, online medical consultations have permeated various facets of daily life.The WeChat Applet for muscle strength empowers patients to transmit their muscle strength information to healthcare professionals without leaving their homes, conserving substantial time and space resources.Similarly, it assumes a pivotal role in facilitating inter-hospital consultations.
Nevertheless, our experiment is not without its limitations.Firstly, it is a single-center study of short duration, and the results may be influenced by individual factors.We did not assess the intra-and inter-inspector reliability of MSV and MSR, which is a limitation.Secondly, due to constraints in muscle strength and measurement range, the instrument is presently incapable of evaluating muscle strength in patients with lower Lovett muscle scores.Lastly, our exclusion criteria precluded the inclusion of patients with Lovett muscle scores of 0 and 1.Consequently, the development of new blood biomarkers is imperative to elucidate clinical intervention strategies pertinent to treatment efficacy in patients with lower Lovett muscle scores.As such, long-term multicenter experimental studies are essential for further validation.

Conclusion
The WeChat Applet for muscle strength measurement exhibits superior quantitative sensitivity, enabling the digitization and visualization of muscle strength in ischemic stroke patients.To some extent, it correlates reasonably well with both the prevailing Lovett muscle score and the 'Upper Limb Movement' section of the NIHSS score.Consequently, it carries substantial implications for clinicians in guiding clinical treatment decisions and assessing the prognosis of ischemic stroke patients experiencing motor dysfunction.In conclusion, it merits further exploration through clinical research, broader application and promotion as a valuable tool for muscle strength assessment and treatment efficacy evaluation.

Figure 1 .
Figure 1.Schematic diagram of the instrument.

Figure 3 .
Figure 3. Study flow chart and participant enrollment results.

Figure 4 .
Figure 4. Box plot illustrating the distributions of MSV and MSR among patients grouped by Lovett muscle score.Notes: MSV, muscle strength value; MSR, muscle strength ratio.*** P < 0.001.

Figure 5 .
Figure 5. Box Plot Illustrating the Distributions of MSV and MSR grouped by NIHSS Score.Notes: MSV, muscle strength value; MSR, muscle strength ratio; NIHSS, National Institute of Health stroke scale.***P < 0.001.
www.nature.com/scientificreports/age, affected side, height, and weight distributions across different Lovett scores and NIHSS scale levels.This approach was utilized to mitigate potential bias stemming from these factors.Upon grouping in accordance with Lovett scores or NIHSS, suitable analytical methods were chosen for correlation analyses involving MSV and MSR, following a validation of data normality.All statistical analyses were executed using SPSS Statistical Software version 23.0 (SPSS, Inc., Chicago, IL, USA).All reported P values were two-tailed, with statistical significance defined as P < 0.05.
27The evaluation of muscle strength is an integral component of a patient's comprehensive assessment and plays a pivotal role in stroke diagnosis, treatment modality selection, and prognosis evaluation27.The utilization of the WeChat Applet, also known as a Mini Program, represents a straightforward and convenient tool accessible directly without the need for a separate app installation.In this study, we employed a WeChat Applet for digitization and visualization-based muscle strength measurement, aiming to ascertain alterations in muscle strength among