Inter-rater reliability of the modified Medical Research Council scale in patients with chronic incomplete spinal cord injury

The Effect of Botulinum Neurotoxin-A (BoNT-A) on Muscle Strength in Adult-Onset Neurological Conditions with Focal Muscle Spasticity: A Systematic Review

Botulinum neurotoxin-A (BoNT-A) injections are effective for focal spasticity. However, the impact on muscle strength is not established. This study aimed to investigate the effect of BoNT-A injections on muscle strength in adult neurological conditions. Studies were included if they were Randomised Controlled Trials (RCTs), non-RCTs, or cohort studies (n ≥ 10) involving participants ≥18 years old receiving BoNT-A injection for spasticity in their upper and/or lower limbs. Eight databases (CINAHL, Cochrane, EMBASE, Google Scholar, Medline, PEDro, Pubmed, Web of Science) were searched in March 2024. The methodology followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and was registered in the Prospective Register of Systematic Reviews (PROSPERO: CRD42022315241). Quality was assessed using the modified Downs and Black checklist and the PEDro scale. Pre-/post-injection agonist, antagonist, and global strength outcomes at short-, medium-, and long-term time points were extracted for analysis. Following duplicate removal, 8536 studies were identified; 54 met the inclusion criteria (3176 participants) and were rated as fair-quality. Twenty studies were analysed as they reported muscle strength specific to the muscle injected. No change in agonist strength after BoNT-A injection was reported in 74% of the results. Most studies' outcomes were within six weeks post-injection, with few long-term results (i.e., >three months). Overall, the impact of BoNT-A on muscle strength remains inconclusive.

Direct (D)-Wave Monitoring Enhancement With Subdural Electrode Placement: A Case Series

PURPOSE

Direct-wave (D-wave) neuromonitoring is a direct measure of corticospinal tract integrity that detects potential injury during spinal cord surgery. Epidural placement of electrodes used for D-wave measurements can result in high electrical impedances resulting in substantial signal noise that can compromise signal interpretation. Subdural electrode placement may offer a solution.

METHODS

Medical records for consecutive patients with epidural and subdural D-wave monitoring were reviewed. Demographic and clinical information including preoperative and postoperative motor strength were recorded. Neuromonitoring charts were reviewed to characterize impedances and signal amplitudes of D-waves recorded epidurally (before durotomy) and subdurally (following durotomy). Nonparametric statistics were used to compare epidural and subdural D-waves.

RESULTS

Ten patients (50% women, median age 50.5 years) were analyzed, of which five patients (50%) were functionally independent (modified McCormick grade ≤ II) preoperatively. D-waves were successfully acquired by subdural electrodes in eight cases and by epidural electrodes in three cases. Subdural electrode placement was associated with lower impedance values ( P = 0.011) and a higher baseline D-wave amplitude ( P = 0.007) relative to epidural placement. No association was observed between D-wave obtainability and functional status, and no adverse events relating to subdural electrode placement were encountered.

CONCLUSIONS

Subdural electrode placement allows successful D-wave acquisition with accurate monitoring, clearer waveforms, and a more optimal signal-to-noise ratio relative to epidural placement. For spinal surgeries where access to the subdural compartment is technically safe and feasible, surgeons should consider subdural placement when monitoring D-waves to optimize clinical interpretation.

Research reporting in cubital tunnel syndrome studies: an analysis of the literature

PURPOSE

There is a strong need for a set of consensus outcomes to be utilized for future studies on cubital tunnel syndrome. The goal was to assess the outcome measures utilized in the cubital tunnel syndrome literature as a way of measuring popularity/acceptability and then to perform a literature review for the most commonly used outcomes.

METHODS

A literature search was performed using the pubmed.gov database and Medical Subject Headings (MeSH). For each article, the following data were abstracted: study type, motor outcome(s), sensory outcome(s), composite outcome(s), patient-reported outcome (PRO) metric(s), pain outcome(s), psychological outcome(s), electrodiagnostic outcome(s), and any other outcomes that were used.

RESULTS

A composite outcome was reported in 52/85 (61%) studies, with the modified Bishop score (27/85; 32%) most common. A motor outcome was reported in 44/85 (52%) studies, with dynamometry (38/85; 45%) most common. The majority of studies (55%) did not report a sensory outcome. The majority of studies (52%) did not report a PRO. A specific pain outcome was reported in the minority (23/85; 27%), with the visual analogue scale (VAS) (22/85; 26%) most common. Pre- and postoperative electrodiagnostic results were presented in 22/85 studies (26%).

DISCUSSION

Understanding current clinical practice and historical outcomes reporting provides a foundation for discussion regarding the development of a core outcome set for cubital tunnel syndrome. We hope that the data provided in the current study will stoke a discussion that will culminate in a consensus statement for research reporting in cubital tunnel syndrome studies.

Does the Score on the MRC Strength Scale Reflect Instrumented Measures of Maximal Torque and Muscle Activity in Post-Stroke Survivors?

It remains unknown whether variation of scores on the Medical Research Council (MRC) scale for muscle strength is associated with operator-independent techniques: dynamometry and surface electromyography (sEMG). This study aimed to evaluate whether the scores of the MRC strength scale are associated with instrumented measures of torque and muscle activity in post-stroke survivors with severe hemiparesis both before and after an intervention. Patients affected by a first ischemic or hemorrhagic stroke within 6 months before enrollment and with complete paresis were included in the study. The pre- and post-treatment assessments included the MRC strength scale, sEMG, and dynamometry assessment of the triceps brachii (TB) and biceps brachii (BB) as measures of maximal elbow extension and flexion torque, respectively. Proprioceptive-based training was used as a treatment model, which consisted of multidirectional exercises with verbal feedback. Each treatment session lasted 1 h/day, 5 days a week for a total 15 sessions. Nineteen individuals with stroke participated in the study. A significant correlation between outcome measures for the BB (MRC and sEMG p = 0.0177, ρ = 0.601; MRC and torque p = 0.0001, ρ = 0.867) and TB (MRC and sEMG p = 0.0026, ρ = 0.717; MRC and torque p = 0.0001, ρ = 0.873) were observed post intervention. Regression models revealed a relationship between the MRC score and sEMG and torque measures for both the TB and BB. The results confirmed that variation on the MRC strength scale is associated with variation in sEMG and torque measures, especially post intervention. The regression model showed a causal relationship between MRC scale scores, sEMG, and torque assessments.

Assessment of variability in motor grading and patient-reported outcome reporting: a multi-specialty, multi-national survey

BACKGROUND

The goal of this survey-based study was to evaluate the current practice patterns of clinicians who assess patients with peripheral nerve pathologies and to assess variance in motor grading on the Medical Research Council (MRC) scale using example case vignettes.

METHODS

An electronic survey was distributed to clinicians who regularly assess patients with peripheral nerve pathology. Survey sections included (1) demographic data, (2) vignettes where respondents were asked to assess on the MRC scale, and (3) assessment of practice patterns regarding the use of patient-reported outcome measures. Inter-rater reliability statistics were calculated for the application of the MRC scale on example vignettes.

RESULTS

There were 109 respondents. There was significant dispersion in motor grading seen on the example vignettes. For the raw responses grading the example vignettes on the MRC scale, Krippendorff's alpha was 0.788 (95% CI 0.604, 0.991); Gwet's AC2 was 0.808 (95% CI 0.683, 0.932); Fleiss' kappa was 0.416 (95% CI 0.413, 0.419). Most respondents reported not utilizing any patient-reported outcome measures across peripheral nerve pathologies.

DISCUSSION

Our data show that there is significant disagreement among providers when applying the MRC scale. It is important for us to reassess our current tools for patient evaluation in order to improve upon both clinical evaluation and outcomes reporting. Consensus guidelines for outcomes reporting are needed, and domains outside of manual muscle testing should be included.

The Dorsal Root Ganglion as a Novel Neuromodulatory Target to Evoke Strong and Reproducible Motor Responses in Chronic Motor Complete Spinal Cord Injury: A Case Series of Five Patients

OBJECTIVES

Current strategies for motor recovery after spinal cord injury (SCI) aim to facilitate motor performance through modulation of afferent input to the spinal cord using epidural electrical stimulation (EES). The dorsal root ganglion (DRG) itself, the first relay station of these afferent inputs, has not yet been targeted for this purpose. The current study aimed to determine whether DRG stimulation can facilitate clinically relevant motor response in motor complete SCI.

MATERIALS AND METHODS

Five patients with chronic motor complete SCI were implanted with DRG leads placed bilaterally on level L4 during five days. Based on personalized stimulation protocols, we aimed to evoke dynamic (phase 1) and isotonic (phase 2) motor responses in the bilateral quadriceps muscles. On days 1 and 5, EMG-measurements (root mean square [RMS] values) and clinical muscle force measurements (MRC scoring) were used to measure motor responses and their reproducibility.

RESULTS

In all patients, DRG-stimulation evoked significant phase 1 and phase 2 motor responses with an MRC ≥4 for all upper leg muscles (rectus femoris, vastus lateralis, vastus medialis, and biceps femoris) (p < 0.05 and p < 0.01, respectively), leading to a knee extension movement strong enough to facilitate assisted weight bearing. No significant differences in RMS values were observed between days 1 and 5 of the study, indicating that motor responses were reproducible.

CONCLUSION

The current paper provides first evidence that bilateral L4 DRG stimulation can evoke reproducible motor responses in the upper leg, sufficient for assisted weight bearing in patients with chronic motor complete SCI. As such, a new target for SCI treatment has surfaced, using existing stimulation devices, making the technique directly clinically accessible.

Chinesisation, adaptation and validation of the Chelsea Critical Care Physical Assessment Tool in critically ill patients: a cross-sectional observational study

PURPOSE

To translate and adapt the Chelsea Critical Care Physical Assessment Tool (CPAx) into Chinese version ('CPAx-Chi'), test the reliability and validity of CPAx-Chi, and verify the cut-off point for the diagnosis of intensive care unit-acquired weakness (ICU-AW).

STUDY DESIGN

Cross-sectional observational study.

METHODS

Forward and back translation, cross-cultural adaptation and pretesting of CPAx into CPAx-Chi were based on the Brislin model. Participants were recruited from the general ICU of five third-grade class-A hospitals in western China. Two hundred critically ill adult patients (median age: 53 years; 64% men) with duration of ICU stay ≥48 hours and Glasgow Coma Scale ≥11 were included in this study. Two researchers simultaneously and independently assessed eligible patients using the Medical Research Council Muscle Score (MRC-Score) and CPAx-Chi.

RESULTS

The content validity index of items was 0.889. The content validity index of scale was 0.955. Taking the MRC-Score scale as standard, the criterion validity of CPAx-Chi was r=0.758 (p<0.001) for researcher A, and r=0.65 (p<0.001) for researcher B. Cronbach's α was 0.939. The inter-rater reliability was 0.902 (p<0.001). The area under the receiver operating characteristic curves of CPAx-Chi for diagnosing ICU-AW based on MRC-Score ≤48 were 0.899 (95% CI 0.862 to 1.025) and 0.874 (95% CI 0.824 to 0.925) for researcher B. The best cut-off point for CPAx-Chi for the diagnosis of ICU-AW was 31.5. The sensitivity was 87% and specificity was 77% for researcher A, whereas it was 0.621, 31.5, 75% and 87% for researcher B, respectively. The consistency was high when taking CPAx-Chi ≤31 and MRC-Score ≤48 as the cut-off points for the diagnosis of ICU-AW. Cohen's kappa=0.845 (p=0.02) in researcher A and 0.839 (p=0.04) for researcher B.

CONCLUSIONS

CPAx-Chi demonstrated content validity, criterion-related validity and reliability. CPAx-Chi showed the best accuracy in assessment of patients at risk of ICU-AW with good sensitivity and specificity at a recommended cut-off of 31.