Brachial Plexus Palsy( During Birth )

Brachial plexus palsy may be seen after injury to the brachial plexus during birth.
Incidences range from 0.1% to 0.4% of live births.

Risk factors –

 Large birth weight,
 Breech presentation,
 Shoulder dystocia,
 Prolonged labor,
 Forceps delivery.

The severity of the palsy depends on which roots of the brachial plexus have been
injured and the extent of injury. Although the incidence of birth palsy has remained
the same, the severity of birth palsies has diminished.
Brachial plexus palsy is classified according to the location of the injury of the brachial plexus.


Seddon classified the injuries into three types -  

The most common types are upper plexus palsy (Erb-Duchenne), in which the supraspinatus and infraspinatus muscles are the most frequently paralyzed;
Whole plexus palsy ("mixed"), in which there is complete sensory and motor paralysis of the entire extremity because of severe injury in all roots of the brachial
plexus;

Lower plexus palsy (Klumpke), in which the muscles of the forearm and hand together with parts served by the cervical sympathetic chain are paralyzed after injury of the eighth cervical and first thoracic nerve roots.

The injury to the brachial plexus can range from neurapraxia or axonotmesis to rupture of roots and avulsion from the spinal cord.
Upper root level injuries (C5-C6) occur most frequently (approximately 90% of patients) and have the best prognosis; lower plexus and whole plexus injuries have the worst prognosis but are much less common.
Geutjens found a higher incidence of avulsion of the upper roots in babies with brachial plexus palsy who were born breech. The babies with avulsions of the upper rootshad a worse prognosis for recovery after exploration and microsurgical-grafting.

Narakas proposed a more detailed classification based on the clinical course of children with brachial plexus palsies during the first 8 weeks after birth; his classification includes a prognosis for each type of injury .

Clinical Features

The diagnosis usually is evident at birth.

In upper root involvement-

The arm is held in internal rotation and active abduction is limited.

The elbow may be slightly flexed or in complete extension.

The thumb is flexed, and occasionally the fingers will not extend.

In complete paralysis, the entire arm and hand is flail.

Pinching produces no reaction.
Vasomotor impairment may be indicated by the relative paleness of the involved extremity.
Roentgenograms of the shoulder may reveal fracture of the proximal humeral epiphysis or fracture of the clavicle.
A clavicular fracture occurs in association with plexus palsy in 10% to 15% of patients.
Pseudoparalysis from a clavicular or proximal humeral fracture should resolve within 10 to 21 days. If limited motion persists after 1 month of age most likely a concomitant brachial plexus palsy is present.
A septic shoulder in an infant also can cause a pseudoparalysis, which can be differentiated from a brachial plexus palsy by evidence of systemic illness and resolution of the pseudoparalysis after the infection is treated.
Characteristic deformities usually develop promptly. The shoulder becomes flexed, internally rotated, and slightly abducted; active abduction of the joint decreases; and external rotation disappears . The shoulder may become posteriorly subluxated and eventually dislocated, or the humeral head becomes flattened against the glenoid.
Advanced glenoid changes were seen by the time the child was 2 years old.
Elbow flexion and forearm supination deformities can occur with a Klumpke palsy (C8-T1) or a mixed brachial plexus lesion. Progressive deformities occur because of weak or absent triceps, pronator teres, and pronator quadratus muscles with an intact biceps muscle. This creates progressive elbow flexion and supination deformity from the unopposed biceps muscle. Radial head dislocation may occur, and the wrist and hand usually are held in extreme dorsiflexion because of the unopposed wrist dorsiflexors.

Evaluation of the brachial plexus injury may include
 Clinical evaluation,
 Electrical diagnostic studies,
 Myelography,
 CT, and MRI.
 Combined myelography, CT, and MRI are more reliable than myelography
alone.
 Large diverticulae and meningoceles are indicative of root avulsions.

Treatment-

Minimal injuries respond well to conservative treatment and, although recovery may
require as long as 18 months, usually residual disability or deformity is slight.
Gilbert and Tassin, and Millesi have suggested that if no evidence of deltoid or biceps recovery is seen by the age of 3 months, surgical exploration should be considered.

The Toronto scale has been used to predict poor outcomes if microsurgical repair or
grafting is not done.

This scale consists of grading elbow flexion, elbow extension, wrist extension, finger extension, and thumb extension. These muscle groups are scored as 0 (no motion), 1 (motion present but limited), or 2 (normal motion) for a maximal score of 12. A score of less than 3.5 predicted a poor long-term outcome without microsurgery.
The aim of treatment in the initial stages is prevention of contractures of muscles and joints.

Gentle passive exercises are begun to maintain full range of passive motion of all joints of the upper extremity, especially full extension of the fingers, hand, and wrist,full pronation, and supination of the forearm, full extension of the elbow, and full
abduction, extension, and external rotation of the shoulder.
Microsurgical nerve repair or grafting has been reported to give satisfactory results in carefully selected patients.

CT scanning and myelography, followed by electromyographic and nerve conduction velocity studies. If these studies show root avulsion from the spinal cord, they recommended no surgery.
If the CT scan and myelogram are normal, they recommended exploration of the brachial plexus and repair of any injuries. Most authors recommend electromyography and CT myelography or MRI evaluation before surgical intervention. The timing of microsurgical intervention still is controversial and rangesfrom 1 to 6 months.

The indications for microsurgical intervention
 Absence of biceps recovery (usually by 3 months of age),
 Toronto score of less than 3.5,
 Total plexopathy with Horner syndrome.

Surgery in unresolved brachial plexus palsy usually is directed toward improving shoulder function and joint contractures. Sever recommended anterior subscapularis
release to correct mild to moderate internal rotation contracture.
Hoffer recommended in addition an anterior release transfer of the latissimus dorsi and teres major to the rotator cuff to improve function.

Wickstrom recommended external rotation osteotomy of the humerus for severe fixed rotation contracture.
Waters recommended that patients with grade I (normal), II (mild increase in glenoid retroversion), or mild grade III (slight
posterior subluxation) glenohumeral deformities have an anterior musculotendinous lengthening of the pectoralis major and posterior latissimus dorsi and teres major transfer to the rotator cuff.
Patients with advanced grade III, grade IV, or grade V glenohumeral deformities should have a humeral derotation osteotomy.
In Klumke palsy , where elbow flexion and forearm supination deformity occur, the biceps tendon can be Z-lengthened and rerouted around the radius to convert it from a supinator to a pronator ; this improves elbow extension and forearm pronation.