Congenital Brachial Plexus Palsy: Anatomy, Diagnosis, & Treatment

Summary Card

Aeitology
Congenital brachial plexus palsy is reduced movement in the upper limb, most often thought to be secondary to traction during the birthing process.

Anatomy
Arising from C5 - T1 of the spinal cord, the brachial plexus has 5 main terminal branches; musculocutaneous, median, ulnar, axillary, and radial.

Presentation
A flaccid upper limb at birth, with or without Horner’s syndrome. Joint creases are present.

Classification
Nerve injury severity is graded by the Seddon and Sunderland classification. The extent of obstetric brachial plexus palsy is classified by Narakas.

Scoring Systems
Outcome measures like the Brachial Plexus Outcome Measure, Mallet Score, and Toronto Test Score help evaluate and track progress over time.

Investigations
Non-invasive imaging and electrophysiology are useful adjuncts, but surgical exploration is currently the most specific investigation.

Multidisciplinary Management
Dedicated multidisciplinary management improves outcomes. Early surgical exploration is advised for complete injuries or if biceps function fails to return in 3 months.

Primary Contributor: Dr Suzanne Thomson, Educational Fellow.
Reviewer: Dr Kurt Lee Chircop, Educational Fellow.

Please note:

Obstetric brachial plexus injury, used synonymously with congeital brachial plexus palsy, implies causation.

Aetiology of Congenital Brachial Plexus Palsy

Key Point

Congenital brachial plexus palsy is reduced movement in the upper limb, most often thought to be secondary to traction during the birthing process.

Congenital brachial plexus palsy is a flaccid paralysis of the arm at birth, where the passive range of movement is greater than the active (Evans-Jones, 2003). It can arise after both vaginal and cesarean deliveries due to:

Excessive head traction away from the shoulder during labor.
Pubic traction or fetal malposition, even without dystocia (Doumouchtsis, 2009)
Birth hypoxia, indicating a multifactorial etiology (DeFrancesco, 2019).

Risk factors for this condition can be maternal, fetal, or at delivery.

Maternal: Diabetes, Primigravida (first-time mother), Black & Hispanic race
Fetal: Macrosomia, Female sex (DeFrancesco, 2019)
Delivery: Shoulder dystocia, Low Apgar scores, Birth hypoxia

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Fun Fact:

The first description of obstetric brachial plexus palsy is attributed to William Smellie, of Lanark, Scotland in 1764 (Smellie, 1764).

Anatomy of the Brachial Plexus

Key Point

The brachial plexus arises from C5 - T1 of the spinal cord. It has 5 main terminal branches; musculocutaneous, median, ulnar, axillary, and radial.

The brachial plexus originates from roots C5 to T1, potentially extending from C4 to T2, and forms a key sensory and motor network connecting the upper limb to the central nervous system. It is organized into roots, trunks, divisions, cords, and branches.

Anatomy of the brachial plexus, Congenital brachial plexus palsy — Anatomy of the left brachial plexus

Roots

Located at the dorsal root ganglion for sensory neurons and anterior horn of the spinal cord for motor neurons; exit behind the vertebral artery.

Trunks & Divisions

Merge from roots passing between the anterior and middle scalene muscles—C5 and C6 (upper trunk), C7 (middle trunk), C8 and T1 (lower trunk).

Each trunk splits into anterior and posterior divisions.

Cords

Cords are named for their position relative to the axillary artery, extending from over the first rib under the clavicle:

Lateral Cord: Originates from anterior divisions of the upper and middle trunks, leading to the lateral pectoral nerve (C5-C7).
Medial Cord: Emerges from the anterior division of the lower trunk, connecting to the medial pectoral, medial brachial cutaneous, and medial antebrachial cutaneous nerves (C8, T1).
Posterior Cord: Formed by the posterior divisions of all trunks, it gives rise to subscapular and thoracodorsal nerves (C5-C8).

Terminal Branches

Each cord supplies nerves to specific regions of the upper limb.

Lateral Cord: Musculocutaneous nerve.
Medial Cord: Ulnar nerve.
Posterior Cord: Radial and axillary nerves.
Combined Contribution: Median nerve from both lateral and medial cords.

Presentation of Congenital Brachial Plexus Palsy

Key Point

A flaccid upper limb at birth, with or without Horner’s syndrome. Joint creases are present. Erb's palsy is the most common.

The presentation of congenital brachial plexus palsy at birth may include a flaccid upper limb, with or without Horner’s syndrome. A temporal examination is important to determine the severity and the resolution.

Most cases are noticed immediately following delivery and may be transient or permanent depending on the severity of injury.

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Tip:

Horner’s syndrome is ptosis, miosis, and anhidrosis due to damage of the sympathetic stellate ganglion.

Erb's Palsy

Erb’s Palsy, named after the German neurologist who first described it in 1874, primarily affects the upper plexus (C5, C6) and results in a “waiter's tip” posture.

Shoulder: Abducted and internally rotated, affected by weakened abductors, latissimus dorsi, and pectoralis muscles.
Elbow: Extended from biceps weakness with unopposed triceps action.
Forearm: Pronated due to weakness in supination.
Wrist: Flexed because of extensor weakness.

Importantly, normal creases are present, indicating movement occurred in utero. This is illustrated in the image below.

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Fun Fact:

Erb’s palsy is often used as a term to describe all congenital brachial plexus palsies but in fact, describes the most common clinical presentation of C5 and C6 nerve root injury.

Other Manifestations

Phrenic Nerve Involvement (C3, C4, C5): Can lead to respiratory symptoms or might only be detected via chest X-ray.
Pan-Plexus Injury: Affects the entire plexus, resulting in a limp arm and possibly Horner’s syndrome if the stellate ganglion (near T1) is impacted.
Klumpke’s Paralysis (C7, C8, T1): Noted for adequate shoulder control but limited wrist movement and diminished fine motor skills in the hand, making it the rarest type in birth-related injuries.

Differential Diagnosis

The most common differential diagnoses for pseudoparalysis are secondary to fractures (humerus or clavicle) and arthrogryposis (characterized by the absence of skin creases). Other potential differentials include:

Spinal cord lesion
Cerebral palsy
Glenohumeral joint sepsis
Infective plexopathy
Radial nerve injury (usually self-limiting)
Biceps trauma (very rare)

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Fun Fact:

Spontaneous recovery may occur but is usually incomplete, especially in children where the lower roots are involved.

Classification of Congenital Brachial Plexus Palsy

Key Point

Nerve injury severity is graded by the Seddon and Sunderland classification. The extent of obstetric brachial plexus palsy is classified by Narakas.

Classic Classifications

Seddon and Sunderland classified nerve injury according to the degree of structural damage. Grade 3-5 injuries (axonotmesis and neurotmesis) will not recover fully and operative intervention is indicated. MacKinnon added a sixth grade, to include the coexistence of mixed grades of injury within a scarred nerve.

This is detailed in the image below.

characteristics of Seddon and Sunderland classifications, Congenital Brachial Plexus Palsy — Characteristics of Seddon and Sunderland classifications

Narakas classification

This classification is widely used to describe the extent of congenital brachial plexus injury.

Grade 1 (C5, C6): Lack of shoulder abduction, elbow flexion, forearm supination. (80% spontaneous recovery)
Grade 2 (C5, C6, C7): Also includes lack of wrist extension. (60% spontaneous recovery)
Grade 3: Pan-plexus with complete flaccid paralysis. (< 50% spontaneous recovery)
Grade 4: Pan-plexus with complete flaccid paralysis and Horner’s syndrome. (< 50% spontaneous recovery)

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Tip:

In Narakas 2 palsy, the most common birth palsy, patients have a "good hand" whose usefulness is limited by lack of shoulder motion.

Scoring Systems

Key Point

Outcome measures like the Brachial Plexus Outcome Measure, Mallet Score, and Toronto Test Score help evaluate and track progress over time.

Outcome measures help evaluate and track progress over time. Key systems include Brachial Plexus Outcome Measure, Mallet Score (Al Quattan, 2024) and Toronto Test Score (Michelow, 1994)

The Mallet Score is visualised below.

The Mallet score in outcome measures of congenital brachial plexus palsy

Toronto Score

This evaluates active joint movements against gravity to determine the need for surgery:

Measurements: Elbow flexion/extension, wrist/finger/thumb extension.
Scoring: 0 (no motion) to 2 (full motion), max score 10.
Indicator: <3.5 at 3 months post-injury suggests surgical exploration.

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Fun Fact:

Tassin, and Gilbert show that functional recovery within 3 months predicts further functional return. Thus, lack of elbow flexion by 3 months suggests the need for surgical exploration and repair (Kay, 1999). (Kay, 1999).

Investigations for Congenital Brachial Plexus Palsy

Key Point

Surgical exploration is the most definitive method for investigation, although non-invasive imaging and electrophysiology can also provide valuable insights.

Primarily diagnosed clinically, with prognosis and surgical decisions supported by investigations. Surgical exploration is the most thorough assessment method.

Diagnostic Imaging

X-ray: Detects fractures or a raised hemidiaphragm.
Ultrasound: Assesses shoulder joint alignment.
MRI:
- T2-Weighted: Identifies nerve avulsions.
- Diffusion Tract Imaging (dTI): Analyzes nerve microstructure.

Intraoperative Electrophysiology
Stimulates muscles and detects sensory-evoked action potentials, enabling precise nerve function mapping during surgery.

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Fun Fact:

Combining clinical evaluation of the phrenic nerve, nerve to serratus anterior, Tinel-Hoffman sign, Horner’s syndrome, and MRI increases diagnostic accuracy to 89%, compared to 80% with MRI alone for root avulsion. (Echalier, 2019).

Management of Congenital Brachial Plexus Palsy

Key Point

Early surgical exploration is recommended for complete injuries or if biceps function does not return within 3 months, involving procedures like nerve reconstruction, neurolysis, grafting, transfers, osteotomies, and fusion.

Treatment for congenital brachial plexus palsy requires a multidisciplinary team including surgeons, nurses, physiotherapists, occupational therapists, psychologists, and orthotists. Surgery options include:

Early Surgery: Directed at reconstructing the nerve injury.
Late Surgery: Optimising function and correcting deformity.

Early Surgery

Early surgery focuses on nerve reconstruction. It is indicated in the following circumstances:

Biceps function does not return by 3 months.
Toronto test score below 3.5 at 3 months.
Complete lesion (Narakas 4) with no recovery signs.
Poor shoulder and forearm function at 9 months, despite some elbow function recovery (Argenta, 2016).

Nerve reconstruction is not recommended over 2 years post-injury due to muscle atrophy; muscle and tendon transfers are the preferred treatment.

The goal of early surgical exploration is to:

Define the nerve injury
Provide neurolysis
Reconstruct nerve defect - sural nerve grafts or nerve transfers
Optimise sensory return - important for central nervous system programming

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Fun Fact:

Evidence supports early nerve repair for neuroprotection and better outcomes, with surgery ideally performed between 3-6 months. (Bourke, 2018, Birch, 2015)

Nerve Transfers

Nerve transfers are used primarily for root avulsions when nerve grafting isn't feasible. The most frequently employed early transfer is the spinal accessory to suprascapular nerve transfer for shoulder stabilisation. There are two main types:

Intra-Plexal Transfers:

Nerve to flexor carpi ulnaris (from ulnar) and nerve to flexor carpi radialis (from the median) to biceps and brachialis branches of musculocutaneous (Oberlin/MacKinnon transfer).
Medial pectoral to musculocutaneous (Brandt and MacKinnon).
Triceps branch to axillary nerve (Leechongavong).

Extra-Plexal Transfers:

Intercostal to musculocutaneous.
Contralateral C7 transfer, often performed endoscopically.
Supraclavicular C4 sensory nerves to C6, 7, and 8 stumps, if grafting is not possible - aims to restore C6 thumb and index finger sensation.
Phrenic nerve transfer is less common due to its impact on respiratory function.

Nerve transfers can also be used to manage shoulder external rotation and elbow flexion deficiency at 12-18 months if there are sufficient donor nerves available to cover all targets (C5-C6 injuries) (Tse, 2015).

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Tip:

Increasingly, Botox is used early to target internal muscle rotators and reduce the risk of glenohumeral subluxation, complementing surgery, or serial casting (Grahn, 2023).

Muscle and Tendon Transfers

Muscle and tendon transfers correct deformities such as shoulder abduction, internal rotation, elbow flexion, forearm supination, wrist flexion, and ulnar deviation with specific corrective strategies.

Shoulder: Subscapularis release, L’episcipo anterior release, teres major transposition, and rotator cuff/deltoid muscle transfers (Elhassan, 2010).
Elbow: Elbow deformity correction involves anterior capsule release, biceps lengthening, Steindler flexorplasty, and muscle transfers including latissimus dorsi and pectoralis. For insufficient local muscle, gracilis transfer with intercostal nerves is used. (Kay, 2010).
Forearm: Z-lengthening of the biceps for supination correction, FCU to brachioradialis transfer, and osteotomy for supination deformities (Hamdi, 2022)
Wrist: FCU or FCR to ECRB, PQ to ECRB, and ECU to ECRB.
MCPJ and IPJ Extensions: FCR and ECRL to EDC, distal EDC advancement, and lumbrical replacement by FDS.
Thumb: EIP to APB, FDS to EPL transfers

Conclusion

Upon completing this article, you will have accomplished the following:

1. Congenital Brachial Plexus Palsy: Gained knowledge about the condition, including its definition, causes, and anatomical aspects.

2. Clinical Presentation: Learned how the condition manifests at birth and the common forms it may take, such as Erb's palsy.

3. Diagnostic Approaches: Understood the key diagnostic tools and techniques used to evaluate brachial plexus palsy.

4. Treatment Strategies: Grasped the surgical and non-surgical management options available for treating the condition.

Congenital Brachial Plexus Palsy: Anatomy, Diagnosis, & Treatment

Summary Card

Aetiology of Congenital Brachial Plexus Palsy

Anatomy of the Brachial Plexus

Roots

Trunks & Divisions

Cords

Terminal Branches

Presentation of Congenital Brachial Plexus Palsy

Erb's Palsy

Other Manifestations

Differential Diagnosis

Classification of Congenital Brachial Plexus Palsy

Classic Classifications

Narakas classification

Scoring Systems

Toronto Score

Investigations for Congenital Brachial Plexus Palsy

Management of Congenital Brachial Plexus Palsy

Early Surgery

Nerve Transfers

Muscle and Tendon Transfers

Conclusion

Further Reading

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Congenital Brachial Plexus Palsy: Anatomy, Diagnosis, & Treatment

Summary Card

Aetiology of Congenital Brachial Plexus Palsy

Anatomy of the Brachial Plexus

Roots

Trunks & Divisions

Cords

Terminal Branches

Presentation of Congenital Brachial Plexus Palsy

Erb's Palsy

Other Manifestations

Differential Diagnosis

Classification of Congenital Brachial Plexus Palsy

Classic Classifications

Narakas classification

Scoring Systems

Toronto Score

Investigations for Congenital Brachial Plexus Palsy

Management of Congenital Brachial Plexus Palsy

Early Surgery

Nerve Transfers

Muscle and Tendon Transfers

Conclusion

Further Reading

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