Evaluating peripheral neuromuscular function with brief movement-evoked pain.

Movement-evoked pain is an understudied manifestation of musculoskeletal conditions that contributes to disability, yet little is known about how the neuromuscular system responds to movement-evoked pain. The present study examined whether movement-evoked pain impacts force production, electromyographic (EMG) muscle activity, and the rate of force development (RFD) during submaximal muscle contractions. Fifteen healthy adults (9 males; age = 30.3 ± 10.2 yr, range = 22-59 yr) performed submaximal isometric first finger abduction contractions without pain (baseline) and with movement-evoked pain induced by laser stimulation to the dorsum of the hand. Normalized force (% maximal voluntary contraction) and RFD decreased by 11% (P < 0.001) and 15% (P = 0.003), respectively, with movement-evoked pain, without any change in normalized peak EMG (P = 0.77). Early contractile RFD, force impulse, and corresponding EMG amplitude computed within time segments of 50, 100, 150, and 200 ms relative to the onset of movement were also unaffected by movement-evoked pain (P > 0.05). Our results demonstrate that movement-evoked pain impairs peak characteristics and not early measures of submaximal force production and RFD, without affecting EMG activity (peak and early). Possible explanations for the stability in EMG with reduced force include antagonist coactivation and a reorganization of motoneuronal activation strategy, which is discussed here.NEW & NOTEWORTHY We provide neurophysiological evidence to indicate that peak force and rate of force development are reduced by movement-evoked pain despite a lack of change in EMG and early rapid force development in the first dorsal interosseous muscle. Additional evidence suggests that these findings may coexist with a reorganization in motoneuronal activation strategy.

A systematic review and meta-analysis of patient-reported outcomes following nerve transfer surgery for brachial plexus injury.

OBJECTIVE: The purpose of this systematic review and meta-analysis was to determine the effect of nerve transfer surgery for brachial plexus injury (BPI) on patient-reported outcomes. LITERATURE SURVEY: MEDLINE, EMBASE, and CINAHL were searched and screened in duplicate for relevant studies on September 25, 2019 and repeated June 24, 2020. METHODOLOGY: The patient population included male and female patients who received nerve transfer surgery for BPI. Further inclusion criteria were: (1) all levels of evidence; (2) published in English; (3) conducted in humans; and (4) report of patient-reported outcome. Two reviewers independently abstracted data regarding injury type, surgical technique, surgical timing, follow-up duration, strength, and patient-reported outcome measures. Quality was assessed in duplicate using the Methodological Index for Non-Randomized Studies criteria. SYNTHESIS: Twenty-one studies involving 464 participants were included in analyses. The mean age ± SD was 32.4 ± 1.8 (range: 5-77) and 89.2% of included participants were male. The mean time to surgery was 5.6 ± 0.6 months and the mean follow-up time was 48.1 ± 8.4 months. The most used patient-reported outcome was the Disabilities of Arm, Shoulder and Hand (DASH), where scores variably improved postoperatively, although the degree of disability remained high. Return to work was reported in five studies, with 66.0% of participants returning to work. Patient satisfaction was assessed in four studies with an overall satisfaction proportion of 64.0%. Pain was assessed in 12 studies using various measures. In studies reporting pain intensity postoperatively, 29.3% of patients were "pain-free" or had "no pain." CONCLUSIONS: Patient-reported outcomes following nerve transfer for BPI are infrequently reported in the literature. Although patient-reported outcomes demonstrate variable postoperative improvement, there is evidence of ongoing limitations and postoperative DASH scores report a high degree of ongoing disability. Future studies with greater reporting as well as validation of patient-reported outcomes within BPI are warranted.

Relationship Between Sensibility Tests and Functional Outcomes in Patients With Traumatic Upper Limb Nerve Injuries: A Systematic Review.

OBJECTIVE: To investigate which tests of hand sensibility correlate with functional outcomes in patients with upper limb traumatic nerve injuries and to assess if composite scales of sensibility correlate with functions. DATA SOURCES: MEDLINE, Embase, and Cochrane Central Register of Controlled Trials were searched in May 2020, with a supplementary search in July 2020. Reference lists of the included publications were hand searched. STUDY SELECTION: Database search found 2437 records. Eligible studies reported on inferential association between sensibility tests and functions pertaining to adults after upper limb nerve repair. Two reviewers independently assessed eligibility. Fifteen publications were included. DATA EXTRACTION: Extracted data contain patient characteristics, surgical procedure, follow-up duration, sensibility tests, and functional assessments. Two reviewers independently assessed data quality. DATA SYNTHESIS: Fifteen publications involving 849 patients were reviewed. All publications reported on median and/or ulnar nerve injuries. Monofilament tests correlated with Short-Form Health Survey (r=0.548, P<.05), pick-up test (r=0.45, P<.05), and function domain of Patient-Rated Wrist and Hand Evaluation Questionnaire (PRWHE) (r=0.58, P<.05). The 8 studies of static and moving 2-point discrimination provided conflicting correlations with activities of daily living (ADL) and/or the pick-up test. Data for area localization and object/shape identification were equivocal as well. No data were found for Ten test and vibration tests. Rosén score sensory domain correlated with ADL (r=0.59; 95% confidence interval [CI], 0.41-0.72) and PRWHE function domain (r=-0.56, P<.05). Medical Research Council sensory scale was related to pick-up test; return to work status; and Disabilities of the Arm, Shoulder, and Hand questionnaire. CONCLUSIONS: Monofilament tests allow practitioners to gather sensibility data meaningful to patients' overall recovery of functions after upper limb nerve trauma. For 2-point discrimination and other sensibility tests, practitioners should be aware that improvement in test performance does not necessarily translate to improved hand function. Findings from the composite scales indicate that hand sensibility, in general, is related to functions. Future research on other common sensibility tests is recommended to explore how the test relates to patients' functions.