Orthopaedic Surgery - Brachial Plexus Birth Palsy

Basics

Brachial plexus birth palsy is caused by stretching or disruption of the brachial plexus during delivery, usually from excessive upward or downward traction on the infant’s arm, shoulder, or neck.

The resulting weakness produces muscle imbalance around the upper extremity. Over time, this imbalance can lead to secondary muscle contractures, joint deformity, and altered growth of the affected bones.

Although the nerve injury occurs at birth, mild cases may not become obvious until the infant begins actively using the affected arm.

Classification

Brachial plexus birth palsy can be classified according to the nerve roots involved.

Type I, or Erb palsy, primarily involves the upper plexus, classically the C5–C6 roots, although adjacent root involvement may occur.

Type II, or total brachial plexus palsy, involves essentially the entire plexus from approximately C5 through T1 and may be referred to as an Erb-Duchenne-Klumpke palsy.

Type III, or Klumpke palsy, predominantly affects the lower plexus, especially C8–T1.

Synonyms

Other names include birth palsy, obstetric palsy, Erb palsy, and Klumpke palsy.

General Prevention

Some cases may be reduced by identifying pregnancies at high risk for difficult delivery.

Cesarean delivery may occasionally be considered when there is marked fetal macrosomia or significant cephalopelvic disproportion.

However, not every brachial plexus birth injury can be predicted or prevented.

Epidemiology

The reported incidence is approximately 1.5 cases per 1,000 live births.

The incidence has declined over time, likely because of improvements in obstetric management.

Erb palsy is considerably more common than Klumpke palsy, occurring approximately four times as often.

No major difference in incidence has been recognized between male and female infants.

Shoulder Dislocation

Approximately 8% of affected infants may develop posterior shoulder dislocation before the age of 1 year.

This usually develops as a secondary consequence of persistent muscle imbalance and internal rotation contracture.

Risk Factors

Important risk factors include fetal malposition, shoulder dystocia, cephalopelvic disproportion, high birth weight, maternal diabetes, and forceps-assisted delivery.

Among these, shoulder dystocia represents one of the most important obstetric risk factors.

Pathophysiology

The degree of nerve injury can range from temporary stretching to complete disruption or avulsion.

The lesion may occur close to the cervical spinal cord, where the nerve roots exit the spinal canal, or farther distally within the neck and shoulder.

More proximal injuries, particularly root avulsions, generally carry a worse prognosis.

Secondary Muscle Imbalance

Persistent denervation leads to muscle weakness and atrophy.

Because some muscle groups recover better than others, an imbalance develops across the shoulder, elbow, wrist, or hand.

Over time, this can cause joint contracture, abnormal joint development, deformity, and altered growth of the affected extremity.

Etiology of Erb Palsy

Erb palsy most commonly results from downward traction on the shoulder or arm, or lateral traction on the neck during a difficult delivery.

This mechanism preferentially stretches the upper roots of the brachial plexus.

Etiology of Klumpke Palsy

Klumpke palsy is associated with upward traction on the arm, producing injury to the lower brachial plexus.

Both patterns can occur during difficult extraction at delivery.

Associated Conditions

Brachial plexus birth palsy is associated with high birth weight and gestational diabetes, both of which increase the likelihood of difficult delivery and shoulder dystocia.

Diagnosis

Signs and Symptoms

The most common finding is reduced spontaneous use of the affected upper extremity.

The arm may rest in a characteristic internally rotated position.

Loss of active shoulder abduction and external rotation is common in upper plexus injuries.

Shoulder Position

In Erb palsy, the shoulder is often held in internal rotation and adduction.

The infant may be unable to fully abduct or externally rotate the arm.

Persistent internal rotation may eventually become fixed because of muscle contracture.

Elbow Findings

Elbow flexion may be weak or absent when the biceps is affected.

As the child grows, an elbow flexion contracture may develop because of muscle imbalance and altered use.

Muscle Atrophy

Chronic denervation may result in visible atrophy of affected muscles.

The involved extremity may also become smaller in both length and girth compared with the opposite side.

Sensory Findings

Sensory loss may occur in more extensive plexus injuries.

Complete plexus palsy is more likely to produce significant sensory impairment than an isolated upper plexus lesion.

The condition itself is generally not painful.

Horner Syndrome

A Horner syndrome may occur in lower plexus injuries, particularly Klumpke palsy.

Its presence suggests injury involving the lower cervical or upper thoracic sympathetic pathways and may indicate a more severe lesion.

History

Reduced movement of the affected arm may be apparent immediately after birth.

In milder cases, the problem may not be recognized until the infant begins using the arm and caregivers notice reduced shoulder movement, weakness, or developing contracture.

Physical Examination

Clinical examination is the primary method of diagnosis.

The infant should be assessed systematically for shoulder, elbow, wrist, and hand function.

The examiner should observe spontaneous movement and stimulate individual muscle groups when possible.

Palpation

The clavicle, proximal humerus, and ribs should be palpated for tenderness.

This helps identify fractures that may mimic a brachial plexus palsy by causing painful pseudoparalysis.

Sensory Examination

Sensation can be assessed by observing the infant’s response to light touch or gentle pinch.

The findings should be compared with those of the opposite arm.

Motor Examination

Function of the major muscle groups of the shoulder, elbow, forearm, wrist, and hand should be evaluated through stimulation and observation.

Particular attention should be paid to recovery of the deltoid and biceps, because their return is useful in determining prognosis and the possible need for surgery.

Erb Palsy Examination

In Erb palsy, the shoulder is typically internally rotated and demonstrates limited or absent abduction and external rotation.

Elbow flexion may also be weak.

A developing internal rotation contracture may be the earliest clinical sign of secondary glenohumeral dysplasia.

Klumpke Palsy Examination

Klumpke palsy predominantly affects the lower plexus.

The major deficits involve finger flexion, intrinsic hand muscle function, and fine motor control.

The hand may appear weak or clawed in severe cases.

Imaging

Plain Radiographs

Radiographs are often obtained shortly after birth to exclude other injuries causing decreased arm movement.

These include clavicle fracture and proximal humeral fracture, which can coexist with brachial plexus birth palsy.

Imaging in Older Children

In children with persistent shoulder imbalance who are being considered for late reconstruction, radiographs and CT can help evaluate the shape, congruity, and deformity of the glenohumeral joint.

These studies are particularly useful in children older than approximately 4 years.

Ultrasound

Ultrasound is useful during the first year of life.

It can be used both as a screening study and as a dynamic examination of glenohumeral alignment, humeral head position, and joint congruity.

It is particularly helpful because much of the infant shoulder is not yet ossified.

MRI

MRI provides detailed evaluation of the glenohumeral joint and surrounding soft tissues.

It can demonstrate posterior subluxation, dysplasia, joint deformity, muscle imbalance, and other structural abnormalities.

Electromyography

Electromyography may be considered when there is no meaningful clinical return of deltoid or biceps function by approximately 3–6 months of age.

Evidence of absent or poor reinnervation may support consideration of nerve reconstruction.

However, EMG can sometimes overestimate recovery in proximal muscles and must be interpreted together with the clinical examination.

Cervical Myelography

Cervical myelography may help determine the level and severity of nerve injury.

The presence of meningoceles or pseudomeningoceles at the cervical root level may indicate root avulsion from the spinal cord.

Root avulsion carries a poor prognosis and may require a different surgical strategy.

Motor Nerve Conduction Studies

Comparative motor nerve conduction studies may help select infants who are candidates for brachial plexus surgery.

These studies may be performed during the first several weeks of life, approximately 10–60 days after birth.

An axonal viability index can be calculated by comparing compound muscle action potential amplitudes between the affected and unaffected limbs.

Differential Diagnosis

Clavicle Fracture

A clavicle fracture can cause an infant to stop moving the arm because movement is painful.

Unlike brachial plexus palsy, the clavicle is usually tender to palpation, and some shoulder movement may still be present.

Radiographs usually confirm the diagnosis.

Proximal Humeral Physeal Fracture

A proximal humeral physeal injury can produce similar pseudoparalysis.

Tenderness is localized over the proximal humerus.

Because the proximal humerus is poorly ossified at birth, the injury may not initially be visible on plain radiographs.

Ultrasound or MRI can be diagnostic, and repeat radiographs after 7–10 days may demonstrate healing changes.

Septic Arthritis of the Shoulder

Septic arthritis may also present with reduced arm movement.

The infant may exhibit pseudoparalysis because movement is painful.

Fever can be minimal or absent in newborns, so infection should remain in the differential when there is pain, irritability, swelling, or systemic concern.

Treatment

General Measures

Initial treatment consists primarily of observation and maintenance of passive range of motion.

Parents should be instructed to stretch the infant’s arm several times each day according to guidance from an occupational or physical therapist.

Specialist Referral

Infants with suspected brachial plexus birth palsy should be referred to a pediatric orthopaedic or peripheral nerve specialist experienced in this condition.

Management decisions can be complex and depend heavily on serial assessment of neurologic recovery.

Spontaneous Recovery

Approximately 80% of affected infants recover spontaneously by 1 year of age.

Because of this high rate of natural recovery, immediate surgery is not required in most newborns.

Continued follow-up is essential to identify infants who fail to recover sufficiently.

Splinting

Routine splinting is generally unnecessary during the initial period.

The emphasis is instead placed on maintaining joint flexibility through gentle passive movement and stretching.

Activity

No general activity restrictions are necessary.

Normal spontaneous use of the extremity should be encouraged as function returns.

Parents should continue passive range-of-motion exercises to prevent contracture.

Occupational and Physical Therapy

Therapists play an important role in teaching parents how to perform stretching safely.

They also help identify early contractures, monitor functional progress, and encourage developmentally appropriate use of the affected arm.

Shoulder Stretching

Particular attention should be given to maintaining shoulder external rotation and abduction.

Loss of passive external rotation may signal developing internal rotation contracture and glenohumeral dysplasia.

Botulinum Toxin

Botulinum toxin A may be injected into overactive internal rotator muscles in selected patients.

It can temporarily reduce muscle imbalance and may assist in maintaining shoulder reduction or delaying more invasive surgery.

Nerve Repair and Reconstruction

When meaningful function does not return during the first several months of life, microsurgical nerve reconstruction may be considered.

Procedures may include direct nerve repair, nerve grafting, or nerve transfer, depending on the lesion.

The exact timing remains controversial but is often considered when recovery is inadequate by approximately 3–6 months.

Timing of Nerve Surgery

Nerve reconstruction is generally most useful when performed relatively early.

Very delayed reconstruction becomes less effective because denervated muscles progressively lose their capacity for meaningful reinnervation.

Root Avulsion

When nerve roots have been avulsed from the spinal cord, direct grafting from the injured root may not be possible.

Alternative nerve transfers or reconstructive strategies may therefore be required.

Tendon Transfers

Tendon transfers may be performed later in childhood when neurologic recovery has plateaued but useful muscles remain available for transfer.

These procedures aim to restore muscle balance and improve specific movements.

Shoulder Tendon Transfers

In young children without advanced fixed glenohumeral dysplasia, tendon transfers may be used to improve external rotation and abduction of the shoulder.

The goal is to restore a more balanced shoulder and improve function.

Release of Internal Rotators

Tight internal rotator muscles may require surgical release when contracture limits external rotation.

This may be combined with tendon transfer or other reconstructive procedures.

Humeral Osteotomy

In older children with established glenohumeral dysplasia or fixed dislocation, a humeral rotational osteotomy may be used.

This procedure repositions the arm into a more functional externally rotated orientation.

It does not restore the normal joint but can significantly improve hand positioning and function.

Restoration of Elbow Flexion

Several muscle transfer procedures may be used to restore elbow flexion.

One option is transfer of the latissimus dorsi, although the choice depends on available muscle function and the specific pattern of weakness.

Wrist and Finger Reconstruction

Tendon transfers for wrist and finger function are less frequently required.

They may be considered in selected children with persistent lower plexus weakness and functional hand deficits.

Follow-Up

Serial clinical assessment is essential throughout infancy and early childhood.

The child should be evaluated for return of motor function, maintenance of passive range of motion, development of contracture, shoulder alignment, and progression of secondary deformity.

Indications for Referral

Any infant with suspected brachial plexus birth palsy should be evaluated by a specialist familiar with obstetric plexus injuries.

This condition requires expertise in pediatric nerve recovery, shoulder development, therapy, and reconstructive surgery.

Prognosis

Approximately 80% of infants recover spontaneously to a substantial degree.

Many of the remaining patients can gain useful function through nerve reconstruction, tendon transfer, osteotomy, or other reconstructive procedures.

Long-Term Function

Even when children adapt well and participate in most activities, residual functional limitations may persist into adolescence.

These may include weakness, restricted shoulder motion, altered limb position, or difficulty with certain sports and overhead activities.

Complications

Important complications include contracture of the shoulder, elbow, or wrist; persistent muscle weakness; sensory loss; reduced growth of the affected extremity; and shoulder subluxation or dislocation.

Growth Disturbance

The affected arm may become smaller in length and circumference because of chronic denervation, reduced muscle activity, and altered loading.

The degree of discrepancy depends on injury severity and recovery.

Glenohumeral Dysplasia

Persistent internal rotation imbalance can progressively alter development of the glenoid and humeral head.

This may result in posterior subluxation, joint dysplasia, or fixed dislocation if not recognized and treated.

Patient Monitoring

The infant should generally be reassessed approximately every 2–3 months during the early period of recovery.

Follow-up should document return of shoulder and elbow function, passive joint motion, hand function, and signs of secondary deformity.

Serial examination guides the timing of electrodiagnostic testing, imaging, and possible surgical intervention.