Brachial plexus birth injury and cerebral palsy lead to a common contracture phenotype characterized by reduced functional muscle length and strength.

Introduction: Brachial plexus birth injury (BPBI) and cerebral palsy (CP) both cause disabling contractures for which no curative treatments exist, largely because contracture pathophysiology is incompletely understood. The distinct neurologic nature of BPBI and CP suggest different potential contracture etiologies, although imbalanced muscle strength and insufficient muscle length have been variably implicated. The current study directly compares the muscle phenotype of elbow flexion contractures in human subjects with BPBI and CP to test the hypothesis that both conditions cause contractures characterized by a deficit in muscle length rather than an excess in muscle strength. Methods: Subjects over 6 years of age with unilateral BPBI or hemiplegic CP, and with elbow flexion contractures greater than 10 degrees on the affected side, underwent bilateral elbow flexion isokinetic strength testing to identify peak torque and impulse, or area under the torque-angle curve. Subjects then underwent needle microendoscopic sarcomere length measurement of bilateral biceps brachii muscles at symmetric joint angles. Results: In five subjects with unilateral BPBI and five with hemiplegic CP, peak torque and impulse were significantly lower on the affected versus unaffected sides, with no differences between BPBI and CP subjects in the percent reduction of either strength measurement. In both BPBI and CP, the percent reduction of impulse was significantly greater than that of peak torque, consistent with functionally shorter muscles. Similarly, in both conditions, affected muscles had significantly longer sarcomeres than unaffected muscles at symmetric joint angles, indicating fewer sarcomeres in series, with no differences between BPBI and CP subjects in relative sarcomere overstretch. Discussion: The current study reveals a common phenotype of muscle contracture in BPBI and CP, with contractures in both conditions characterized by a similar deficit in muscle length rather than an excess in muscle strength. These findings support contracture treatments that lengthen rather than weaken affected muscles. Moreover, the discovery of a common contracture phenotype between CP and BPBI challenges the presumed dichotomy between upper and lower motor neuron lesions in contracture pathogenesis, instead revealing the broader concept of "myobrevopathy", or disorder of short muscle, warranting increased investigation into the poorly understood mechanisms regulating muscle length.

Use of botulinum toxin type A in the management of neonatal brachial plexus palsy.

OBJECTIVE: To evaluate functional outcomes and the impact on surgical interventions after the use of botulinum neurotoxin type A (BoNT-A) for muscle imbalance, cocontractions, or contractures with neonatal brachial plexus palsy. DESIGN: A retrospective cohort study. SETTING: A brachial plexus center in a tertiary children's hospital. PARTICIPANTS: Fifty-nine patients with neonatal brachial plexus palsy (75 injection procedures, 91 muscles and/or muscle groups) received BoNT-A injections (mean age at injection, 36.2 months; range, 6-123 months; 31 boys; 30 right-sided injuries, 28 left-sided injuries, 1 bilateral injury). METHODS: Data collected retrospectively from medical records, from procedure notes and clinic visits before BoNT-A use, at ≤6 months follow-up (BoNT-A active [BA]) and at ≥7 months follow-up (BoNT-A not active [BNA]) included demographics, injection indication, side, and site(s), previous surgical history, occupational therapy and/or physical therapy plan, and outcome measurements. MAIN OUTCOME MEASUREMENTS: Outcomes assessed before and after injections included active and passive range of motion, Mallet and Toronto scores, parent comments about arm function, preinjection surgical considerations, and postinjection surgical history. RESULTS: Injection procedures included 51 to shoulder internal rotators, 15 triceps, 15 pronator teres, 9 biceps, and 1 flexor carpi ulnaris. Active and passive shoulder external rotation (SER) range of motion improved after shoulder internal rotator injections (P = .0003 and P = .002, respectively), as did Mallet scores with BA; the latter were sustained with BNA. Surgical intervention was averted, modified, or deferred after BoNT-A in 45% (n = 20) under surgical consideration before BoNT-A. Active elbow flexion improved in 67% (P = .005), sustained BNA (P = .004) after triceps injections; 2 of 7 patients averted surgery. Active supination improved with BA (P = .002), with gains sustained BNA (P = .016). Passive elbow extension improved after biceps injections by an average 17° (P = .004) BA, although not sustained BNA. CONCLUSIONS: BoNT-A is an effective adjunct to therapy and surgery in managing muscle imbalance, cocontractions, and contractures in neonatal brachial plexus palsy. Use of BoNT-A can result in averting, modifying, or deferring surgical interventions in a number of affected children.

Arthroscopically assisted Sever-L'Episcopo procedure improves clinical and radiographic outcomes in neonatal brachial plexus palsy patients.

BACKGROUND: Muscle pathology resulting in internal rotation contractures in children with neonatal brachial plexus palsy places abnormal stresses on the glenohumeral joint and limits global shoulder function. The objective of this study was to assess the clinical and radiographic outcomes in children treated with an arthroscopic release with or without tendon transfer, the so-called arthroscopically assisted Sever-L'Episcopo procedure. METHODS: Fifty children with an average age of 5.1 years who underwent an arthroscopic release with or without tendon transfer were retrospectively reviewed. Clinical outcomes were assessed using Mallet classification scores, whereas glenoid retroversion and posterior humeral head subluxation were measured on magnetic resonance images to quantify radiographic outcomes. Mean clinical follow-up was 30 months (range: 24 to 65 mo) and mean radiographic follow-up was 24 months (range: 11 to 42 mo). RESULTS: Aggregate Mallet score improved significantly from 12.6 to 16.3 (P<0.0001), with shoulder abduction from 3.4 to 3.8 (P=0.0007), shoulder external rotation from 2.2 to 3.3 (P<0.0001), hand-to-neck from 2.3 to 3.2 (P<0.0001), and hand-to-mouth from 2.3 to 3.3 (P<0.0001). Hand-to-spine Mallet score did not significantly change from preoperative (2.4) to postoperative (2.6) (P=0.1348), although 4 patients experienced a loss in internal rotation function. Forty-eight percent of children improved by at least 4 points on the total Mallet score. Glenoid retroversion improved from 25 to 14.1 degrees (P<0.0001) and percent humeral head anterior to the central axis of the scapula increased from 30.5% to 38.8% (P=0.0001). Sixty-seven percent of patients demonstrated glenohumeral joint remodeling on magnetic resonance imaging. No child exhibited a worsening of glenohumeral anatomy. CONCLUSIONS: An arthroscopic release with or without tendon transfer is effective in reducing internal rotation contractures and increasing global shoulder function. Both clinical and radiographic outcomes were significantly improved at 2-year follow-up. Furthermore, in the majority of children, aggregate, abduction, and external rotation Mallet scores all increased without sacrificing internal rotation. LEVEL OF EVIDENCE: Therapeutic Level IV.