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Erb’s Palsy

- See:
     - Obstetrical Paralysis:
     - Upper Trunk Brachial Plexus Injuries in Adults;

- Discussion:
    - most common birth related neuropraxia (about 48%);
    - lesion of C5 & C6 roots are usually produced by widening of the head shoulder interval (in some cases C7 is involved as well);
    - may occur at birth, producing lesion of axillary nerve, musculocutaneous, & suprascapular nerve;
    - muscles most often paralyzed are supraspinatus and infraspinatus because the suprascapular nerve is fixed at the suprascapular
              notch; (Erb's point)
    - in more severely affected patients deltoid, biceps , brachialis, and subscapular is affected (C5 and C6 );
    - chronic internal rotation contracture leads to secondary osseous changes (increased glenoid retroversion) and posterior subluxation
           of the shoulder;
           - mean glenoid retroversion on the injured side is approximately 26 deg vs 6 deg on the normal side;
           - w/ increasing retroversion, there will be associated subluxation, dislocation (w/ development of false glenoid), and w/
                    increasing severity, there will be flattening of the humeral head;
    - diff dx:
           - pseudoparalysis resulting from clavicle and humerus fractures or osteomyelitis must be excluded;
           - see: clavicular frx in infants;
    - prognosis:
           - brachial plexus injuries range from mild neuropraxia w/ early recovery to complete disruption with no potential for recovery;
           - fortunately, between 80% to 90% of children with such injuries will attain normal or near normal function;
           - attempt to determine whether the lesion is preganglionic or post-ganglionic;
                 - preganglionic lesions have a worse prognosis (avulsion of the roots from the cord which disrupts the sympathetic chain)
                 - preganglionic lesions may be more common w/ breech deliveries;
                 - persistent Horner's sign (ptosis, myosis, and anhydrosis) is a sign of proximal injury - preganglionic injury;
                 - preganglionic injuries are unlikely to recover;
           - follow upper trunk innervation:
                 - affected children who show clinical or EMG evidence of biceps function before 6 months of age have near normal to
                           excellent function;
                 - in addition to biceps, follow motor strength of shoulder abduction, wrist extension, and thumb extension;

- Exam:
    - arm cannot be raised, since deltoid (axillary nerve ) & spinati muscles (suprascapular nerve) are paralyzed;
    - elbow flexion is weakened because of weakness in biceps & brachialis;
    - if roots are damaged above their junction, paralysis of rhomboids and  serratus anterior is added, producing weakness in retraction
              and protraction of scapula;
    - after the age of 6 months, contractures begin to develop (adduction and internal rotation contractures);
    - paralytic supination deformity of the forearm;
          - develops from imbalance between supinator and the paralyzed pronator muscles (pronator teres and pronator quadratus);
          - passive correction of the deformity is possible initially, but becomes fixed w/ later growth as the interosseous membrane
                    becomes fixed;
          - chronic changes include volar subluxation of the distal end of the ulna or proximal head of the radius;

- Radiographs:
    - look for presence of cervical rib;
    - in the report by Becker J, et al (2002), the authors noted that in a series of 42 infants found to have a cervical
           rib, 28 newborns had an Erb's palsy;
           - they conclude that a cervical rib was a risk factor for an Erb's palsy;
           - ref: The cervical rib. A predisposing factor for obstetric brachial plexus lesions

- Management:
    - during first six months gentle ROM exercises are necessary to retain external rotation & abduction at the shoulder;
    - EMG will help distinguish reversible vs irreversible nerve damage and will help map out anatomy of the injury;
    - nerve grafting controversies:
           - children who show no clinical or electromyographic evidence of biceps, muscle function at age 6 months
                   in patient w/ C5-6 brachial plexus palsy have a poor prognosis for functional recovery;
                   - pts should undergo early brachial plexus exploration and nerve grafting to improve function of dennervated muscle;
           - other authories recommend nerve grafting before 6 months of age, noting that after 6 months, muscle contractures occur due
                   to unopposed muscle forces;
    - release of contractures:
           - indicated for patients w/ internal rotation & adduction contraction of the shoulder;
           - chronic internal rotation contracture leads to secondary osseous changes (increased glenoid retroversion) and posterior
                     subluxation of the shoulder;
           - early operative management includes: release of subscapularis (and in some severe cases release of anterior joint capsule and
                   pectoralis major);
                   - soft tissue release is performed inorder to regain external rotation and to prevent pathologic osseous changes;
                   - it is important to note that aggressive anterior releases may result in anterior instability;
                   - some authors feel that the pectoralis does not usually result in contracture and does not require release;
           - technique of release of subscapularis from the scapula:
                   - as compared to releasing the subscapularis off of the humerus, this technique avoids anterior instability;
                   - patient is placed in the lateral position;
                   - make a longitudinal incision along the lateral border of the scapula;
                   - identify the fibers of the latissimus muscle (over the lateral aspect of the scapula), and retract it inferiorly;
                   - subscapularis is elevated off of the anterior surface of the scapula;
                   - increase in external rotation demonstrates adequacy of the release;
                   - avoid injury to the subscapular artery and nerve at the scapular notch and at the anteromedial aspect of the glenoid neck;
                   - splint is applied w/ arm in abduction and external rotation for 3 months, followed by 3 months of night splinting;
    - tendon transfers:
          - indicated to counteract the shoulder adductors and internal rotators;
          - generally performed prior to age 7 yrs;
          - latissimus dorsi may be transfered to the rotator cuff / greater tuberosity (augments external rotation power);
                   - in the report by Edwards TB, et al, a retrospective study of the results of latissimus dorsi and teres major transfer in the
                           treatment of Erb's palsy was conducted in 10 patients;
                   - all patients underwent release of the pectoralis major and transfer of the latissimus dorsi and teres major tendons to the
                           rotator cuff at a mean age of 7 years and 2 months;
                   - active shoulder abduction improved from a mean of 72 degrees preoperatively to 136 degrees postoperatively;
                   - postoperative shoulder active external rotation averaged 64 degrees;
                   - all but one patient were satisfied with the final outcome;
                   - ref: Results of latissimus dorsi and teres major transfer to the rotator cuff in the treatment of Erb's palsy.
      - posterior glenohumeral subluxation:
          - as w/ DDH, aggressive treatment early on may reverse the deformity, where as older children may require derotational
          - limitation of external rotation;
          - for older children (older than 5 yrs of age) with fixed bony adaptive changes, proximal humeral external rotation osteotomy
                  can be considered;
          - in late cases, w/ a deficient posterior glenoid consider humeral derotational osteotomy;
    - forearm pronation deformity:
          - correction of the supination deformity requires early intervention;
          - consider brachioradialis transfer through the interosseous membrane;
          - ref: A surgical technique for pediatric forearm pronation: brachioradialis rerouting with interosseous membrane release.

Trends in Pediatric Orthopedics--Symposium: Surgical Treatment of Brachial Plexus Birth Palsy.

Duchenne-Erb palsy. Experience with direct surgery.

Glenoid deformity secondary to brachial plexus birth palsy

Glenohumeral deformity secondary to brachial plexus birth palsy