Erbs Palsy

Overview

Definition

Erb's palsy, or Erb-Duchenne palsy, is a form of obstetric brachial plexus paralysis (OBPP) resulting from injury to the upper trunk of the brachial plexus, specifically the nerve roots C5 and C6, and sometimes C7. This typically leads to weakness or paralysis of the shoulder abductors, external rotators, and elbow flexors.

Epidemiology

• Incidence: Estimated at 0.5 to 4.6 per 1,000 live births globally.
• Location: The upper trunk (C5-C6) is involved in approximately 90% of all OBPP cases, making Erb's palsy the most common form.
• Demographics: Affects newborns, often associated with a complicated delivery. There is no sex predilection.
• Laterality: Usually unilateral.

Classification

Erb's palsy is classified based on the severity of nerve injury (from minor stretch to complete avulsion):

Severity (Sunderland/Seddon Classification)	Description	Prognosis
Neurapraxia (Grade I)	Temporary block of conduction; axon intact.	Excellent, full recovery often within 3 months.
Axonotmesis (Grade II/III)	Axon disruption; varying degrees of endoneurial sheath injury.	Good to Fair; requires nerve regeneration.
Neurotmesis (Grade IV/V)	Partial or complete transection of the nerve.	Poor; requires surgical intervention for functional recovery.
Avulsion (Grade VI)	Nerve root severed from the spinal cord (preganglionic injury).	Worst prognosis, requires nerve transfer or grafting.

Topographical Classification (Based on roots involved): 1. Erb-Duchenne Palsy (Upper Plexus): C5, C6 (most common). 2. Extended Erb's Palsy: C5, C6, C7. 3. Klumpke's Palsy (Lower Plexus): C8, T1 (rare, ~1%). 4. Total Plexus Palsy: C5-T1 (involves the entire arm).

Pathophysiology

Mechanism

The injury occurs due to excessive traction or lateral stretching of the infant's head and neck relative to the shoulder during delivery, frequently associated with shoulder dystocia or instrumental delivery. * Injury Site: The roots (C5 and C6) are stretched or torn where they emerge from the intervertebral foramina or as they form the upper trunk lateral to the scalene muscles. * Muscles Affected (C5/C6): Deltoid, supraspinatus, infraspinatus, biceps, brachialis (leading to loss of shoulder abduction, external rotation, and elbow flexion). Also often includes the wrist extensors (C6).

Risk Factors

• Maternal Factors: Diabetes, excessive weight gain, obesity, multiparity.
• Fetal Factors: Macrosomia (birth weight $>4,000$ g), prolonged second stage of labor, atypical fetal presentation (e.g., breech).
• Intrapartum Factors: Shoulder dystocia (the head delivers but the anterior shoulder is impacted against the maternal symphysis), high velocity of delivery, vacuum or forceps assistance, failed attempted version.
• Iatrogenic Factors: Excessive lateral traction by the delivering physician when attempting to free the shoulder.

Protective Factors

• Optimized Prenatal Care: Strict glycemic control in diabetic mothers.
• Delivery Planning: Consideration of elective Cesarean section for estimated fetal weight (EFW) exceeding $4,500$ g (or $4,000$ g in diabetic mothers) or anticipated shoulder dystocia.
• Skilled Delivery Practices: Utilization of maneuvers (e.g., McRoberts maneuver, suprapubic pressure) to resolve shoulder dystocia without excessive traction on the head/neck.

Clinical Presentation

Signs and Symptoms

Cardinal Features

The classic posture, often described as the "waiter's tip" position, is characterized by: 1. Shoulder Adduction and Internal Rotation (unopposed pectoralis major, latissimus dorsi, and subscapularis). 2. Elbow Extension (loss of biceps and brachialis function). 3. Forearm Pronation (unopposed pronator teres, loss of biceps supination). 4. Wrist and Finger Flexion occasionally involved if C7 is affected.

Early Signs (Neonatal)

• Asymmetry of spontaneous arm movement compared to the contralateral side.
• Absence of the Moro reflex on the affected side.
• Flaccid arm presentation immediately post-delivery.
• Grasping reflex usually preserved (C8-T1 intact, distinguishing it from total plexus injury).

Advanced Signs (If unresolved)

• Shoulder Girdle Contractures: Internal rotation contracture is the most common long-term deformity.
• Bony Deformities: Glenoid dysplasia (flattening of the humeral head), posterior subluxation of the humeral head due to chronic muscular imbalance.
• Limb Length Discrepancy: Affected arm may be shorter.

Atypical Presentations

• Horner Syndrome: Suggests lower root involvement (T1) or avulsion (preganglionic injury, affecting the sympathetic chain), characterized by ptosis, miosis, and anhidrosis on the affected side.

Physical Examination

Inspection

• Posture: Waiter's tip positioning.
• Skin: Look for bruising, swelling, or clavicular fracture (crepitus or visible callus) which can accompany the injury.
• Asymmetry: Compare limb size and resting posture.

Palpation

• Assess for Crepitus over the clavicle or humerus, ruling out concomitant orthopedic injuries.
• Evaluate muscle tone and tenderness.

Special Tests (Motor Grading using Modified British Medical Research Council Scale)

• Maneuvers: Test specific muscle groups supplied by C5 and C6:
  • Shoulder Abduction/External Rotation: Deltoid (C5), Infraspinatus (C5-C6).
  • Elbow Flexion: Biceps (C5-C6), Brachialis (C5-C6).
• Assessment Scale: The Active Movement Scale (AMS) is commonly used specifically for OBPP in infants, grading movement on a scale of 0 to 7.

Diagnostic Approach

History Taking

Key Questions

• Perinatal History: Mode of delivery, birth weight (macrosomia?), need for operative assistance, presence of shoulder dystocia, specific obstetrical maneuvers used.
• Initial Presentation: Was the paralysis noted immediately?
• Progression: Has function improved, worsened, or plateaued since birth?
• Associated Injuries: Has the baby had treatment for clavicle or humeral fractures?

Red Flags (Indicating Severe Injury/Surgical Referral)

• Lack of Biceps Function (no elbow flexion) at 3 months of age.
• Absence of any recovery in shoulder or elbow function by 3-6 months.
• Presence of Horner Syndrome (suggests T1 avulsion).
• Concurrent flail hand (suggests total plexus palsy).

Laboratory Tests

Laboratory tests are generally not useful for the primary diagnosis of Erb's palsy.

Imaging

Recommended (Initial Assessment)

• Plain Radiographs: X-rays of the shoulder, clavicle, and humerus are mandatory to exclude associated bony injuries (fractures are common in up to 10% of cases).

Advanced (For Surgical Planning or Lack of Recovery)

• Electrodiagnostic Studies (After 3-4 Weeks):
  • Nerve Conduction Studies (NCS): Assesses speed and amplitude. Reduced amplitude suggests axonal injury.
  • Electromyography (EMG): Assesses muscle denervation (fibrillation potentials, positive sharp waves) and reinnervation (polyphasic motor units). Crucial at 3-6 months to determine the severity and extent of denervation.
• Magnetic Resonance Imaging (MRI) / Magnetic Resonance Neurography (MRN):
  • Used to visualize the nerve roots and plexus anatomy, especially to look for pseudomeningoceles (indicative of root avulsion—a preganglionic injury). Typically performed near the time of potential surgical intervention (3-6 months).
• Ultrasound: Can be used in early infancy to assess the posterior shoulder for subluxation and track contracture development, but is highly operator-dependent.

Management

Acute Management (First 0-4 Weeks)

Immediate

• Avoid Over Handling: Support the limb and avoid traction or unnecessary movement.
• Conservative Care: If a concomitant clavicular or humeral fracture is present, manage this first (e.g., figure-of-eight bandage, gentle sling).

Stabilization

• Gentle Positioning: Place the arm across the abdomen with the elbow bent, preventing the development of excessive internal rotation contracture.
• Parent Education: Educate parents on safe mobilization and handling, emphasizing the importance of preventing capsular contracture.

Chronic Management

The cornerstone of non-operative management is physical therapy.

Pharmacological

• Botulinum Toxin Type A (Botox): Used in older infants/children (typically >1 year) to selectively weaken antagonist muscles (e.g., pectoralis major, latissimus dorsi, subscapularis) contributing to the internal rotation contracture, facilitating stretching and improving range of motion (ROM) before or instead of surgery.
• Analgesia: Rarely required, primarily for associated fractures.

Non-pharmacological (Physical Therapy/Occupational Therapy)

• Start Time: Initiate physical therapy as soon as diagnosis is confirmed, usually within the first weeks of life.
• Goals: Maintain passive range of motion (PROM), prevent joint contractures (especially internal rotation contracture), and encourage spontaneous recovery.
• Techniques: Gentle PROM exercises performed 3–5 times daily by parents. Focus on shoulder external rotation, abduction, and elbow flexion/supination.
• Splinting: Used sparingly, primarily to maintain a functional position or prevent specific contractures (e.g., aeroplane splints are rarely used due to risk of joint stiffness).

Treatment Algorithms (Based on Age and Recovery)

First-Line: Observation and Physical Therapy (0 to 6 months)

• Initial Approach: All cases are treated conservatively initially with PT/OT and monitoring.
• Key Monitoring Point (Biceps Function): If spontaneous recovery of biceps function (Grade 3 or higher) occurs by 3 months, the prognosis is generally excellent, and continued conservative management is appropriate.

Second-Line: Surgical Intervention (4 to 9 months)

Criteria for Surgical Referral (Nerve Reconstruction): 1. NO functional elbow flexion (biceps strength < M3/AMS 3) by 3 to 6 months of age. This is the single most critical indication. 2. No recovery of any key function (deltoid, biceps) by 6-9 months confirmed by EMG/NCS showing denervation/avulsion.

Surgical Options (Nerve Reconstruction): * Neurolysis: Freeing the nerve from scar tissue (scar neuroma). * Nerve Grafting: Replacing the damaged segment with a sensory nerve graft (e.g., from the sural nerve). Indicated for discontinuity of C5/C6. * Nerve Transfer (Neurotization): Transferring a less crucial, adjacent motor nerve (e.g., intercostal nerve, accessory nerve) to the damaged C5/C6 distal stump. Often preferred for preganglionic injuries (avulsions).

Refractory Cases (After 1 Year of Age)

If nerve recovery is incomplete, the focus shifts to treating secondary deformities and contractures (secondary reconstructive surgery). * Shoulder: Tendon transfers (e.g., Latissimus Dorsi/Teres Major transfer to restore external rotation) and osteotomies (e.g., humeral rotational osteotomy) to correct fixed internal rotation. * Elbow/Forearm: Steindler flexorplasty or osteotomies.

Complications

Common

• Glenohumeral Joint Dysplasia/Deformity: Chronic muscle imbalance (strong internal rotators vs. weak external rotators) leads to posterior subluxation of the humeral head and glenoid retroversion.
• Internal Rotation Contracture: The most common and functionally limiting long-term sequela.
• Muscle Atrophy and weakness.

Serious

• Shoulder Dislocation/Subluxation: Can become fixed and require major surgery.
• Growth Inhibition: Limb length discrepancy.
• Complex Regional Pain Syndrome (CRPS): Rare in pediatric cases.

Long-term

• Decreased functional range of motion and poor functional use of the affected extremity (fine motor skills usually preserved unless C7 is involved).
• Psychosocial issues related to limb appearance and functional limitations.

Prognosis

Factors Affecting Outcome

• Severity of Injury: Neurapraxia has the best prognosis. Avulsion has the worst.
• Extent (Number of Roots): C5-C6 (good prognosis) versus Total Plexus (poor prognosis).
• Speed of Recovery: Functional recovery by 3 months is highly favorable. Delayed or absent recovery by 6 months portends poor outcome without surgery.
• Presence of Horner Syndrome: Poor prognostic indicator, suggesting preganglionic T1 injury.

Survival

Erb's palsy does not affect life expectancy (mortality), but significant functional morbidity is possible.

Quality of Life

Approximately 80-90% of children with Erb's palsy achieve near-normal or excellent function with conservative management if the injury is neurapraxic or minor axonotmetic. Those requiring surgery maintain functional deficits but can achieve purposeful use of the hand and arm, dependent on timely intervention.

Prevention

Primary

• Maternal Health Optimization: Strict monitoring and control of maternal diabetes.
• Risk Assessment: Identifying macrosomic fetuses and considering planned Cesarean delivery for high-risk cases (e.g., estimated fetal weight > $4,500$ g or prior history of shoulder dystocia).

Secondary

• Intraoperative Maneuvers: Skilled management of shoulder dystocia using non-traction techniques (e.g., McRoberts, gentle rotation) to minimize forces applied to the fetal head/neck.

Tertiary

• Early Recognition and Rehabilitation: Immediate initiation of physical therapy to prevent contractures, which severely limit the outcomes of later nerve or orthopedic surgery.

Special Populations

Pediatric

• Infants ($\le 1$ year): Focus on monitoring recovery, parental education, and maintaining PROM. Surgical decisions (nerve repair) are time-sensitive, ideally performed between 4 and 9 months.
• Children (Age > 2 years): Treatment shifts to secondary reconstruction (tendon transfers, osteotomies) to correct residual functional deficits and bony deformities.

Geriatric and Pregnancy

Not applicable, as Erb's palsy is an obstetric injury.

Comorbidities

• Associated Fractures: Must be managed first (immobilization) but should not significantly delay the initiation of passive range of motion exercises (once clearance from the orthopedic team is given).

Clinical Pearls

Diagnostic

• Biceps at 3 Months: The single most important clinical marker. If the baby cannot actively flex the elbow against gravity by 3 months, surgical consultation is urgent.
• Clavicle First: Always rule out a clavicle fracture (which may mimic paralysis) before diagnosing brachial plexus injury.

Treatment

• Time is Nerve: The window for primary nerve surgery (grafting/transfer) closes by 9 to 12 months. Early referral to a specialized center is imperative if recovery lags.
• The Subscapularis Problem: The internal rotation contracture stems from unopposed action of the subscapularis and pectoralis major. Aggressive stretching into external rotation is necessary, or Botulinum toxin may be considered later to relax these internal rotators.

Pitfalls

• Delayed Referral: Mistaking nerve injury for neurapraxia and waiting too long (e.g., past 9 months) before surgical assessment severely limits the potential for nerve regeneration.
• Over-Immobilization: Avoiding excessive splinting, which can lead to joint stiffness (especially the elbow and shoulder capsule).

Recent Updates

Guidelines

• The American Academy of Orthopaedic Surgeons (AAOS) and other specialty societies emphasize the critical window for nerve exploration and repair (4–9 months) based on lack of anti-gravity biceps function.
• Growing evidence supports the use of intercostal-to-biceps fascicular nerve transfers over grafting for specific patterns of C5/C6 avulsion, often leading to quicker and stronger recovery of elbow flexion.

Evidence

• Recent research confirms that MR Neurography is becoming a critical tool for pre-operative planning, offering better visualization of nerve roots and the plexus than standard MRI, helping distinguish pre- from post-ganglionic injury (avulsion).

Controversies

• Role of Botulinum Toxin: The optimal timing and frequency of Botulinum Toxin A injection to address muscular imbalance (internal rotation bias) remains debatable, though its use is common prior to or instead of secondary reconstruction.
• Early vs. Late Surgery: While the 3-6 month rule for biceps recovery is standard, some newer protocols advocate for earlier intervention (e.g., 4 months) if electrodiagnostic studies confirm severe axonal disruption.

Key References

Guidelines

• American Academy of Orthopaedic Surgeons (AAOS) Clinical Practice Guidelines on Diagnosis and Management of Obstetric Brachial Plexus Palsy.
• Consensus statements from the International Federation of Societies for Surgery of the Hand (IFSSH) regarding brachial plexus injury management.

Studies

• Waters P. (Multiple papers): Landmark longitudinal studies defining outcomes and the role of surgery in OBPP.
• Sunderland S. (Classification of nerve injury severity).

Reviews

• Reviews in the Journal of Bone and Joint Surgery (JBJS) and Seminars in Plastic Surgery focusing on the surgical algorithms and timing for nerve reconstruction in OBPP.

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Disclaimer: This information is provided for educational purposes and is intended for use by qualified healthcare professionals. It does not constitute medical advice, diagnosis, or treatment. Clinical decisions must always be made based on individual patient circumstances and the clinician's judgment, considering the most current evidence and local protocols.