- 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
osteotomy;
- 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.