7.3. Traumatic Brachial Plexus Injury
- General Principles:
- The longitudinal excursion of the brachial plexus is 15.3 mm
- The greater the traction the greater the injury
- Primary roots are most susceptible to traction injury (arranged in parallel bundles rather than lattice and therefore decreased tensile strength)
- Shoulder depression, lateral head flexion contralaterally injure the upper and medial trunk
- Traction on the hyperabducted arm; greatest traction on the lower > middle > upper trunk
- Preganglionic injuries usually are caused by a avulsion of the root
- Traction injury may affect all or a portion of the plexus to a varying degree
- C5 and C6 ruptures after leaving exit foramina; C8, T1 rupture closer to the spinal cord
Avulsion Injury
- Differential diagnosis:
- High speed MVA; motorcycles most common
- Football, skiing, mountain climbing accidents
- C5–C6 lesions after severe trauma:
- 27% avulsions
- 33 % ruptures
- C8–T1 roots:
- 98% avulsion
- 1–2% rupture
- Clinical signs and symptoms:
- Violent trauma
- Total plexopathy involvement common, C8–T1 > C5–C6
- Early consistent burning pain in an anesthetic hand; severe proprioceptive loss
- Horner's syndrome (C8–T1 avulsion)
- Paralysis of serratus anterior, rhomboid, infra and supraspinatus muscles
- Negative supraclavicular Tinel's signs
- Associated spinal cord symptoms and signs
Radiographic Features
- Traumatic meningocele
- Fracture of the transverse process
- Flattening of the root sleeve
- Extravasation of contrast through the torn root sleeve during a myelogram
Obstetric Complications
- General Features:
- Rare in modern times; lateral neck traction or possibly damage in utero (seen following C-sections)
- Preganglionic root avulsion, extra foraminal rupture, lesions in continuity
- Males = females; R > L arm
- Diabetic, multiparous, obese mothers; > 4500 gram fetuses
- C5–C6 upper trunk; C5–C6, C7 upper and middle trunk type:
- Most common type
- Extraforaminal rupture
- During vertex > breach delivery
- Sensory involvement < than motor
- Right extremity > left (right shoulder caught under the pubic bone)
- Bilateral involvement rare < 6%; associated with breach delivery
- C8/T1 (in isolation):
- Rare
- Most often avulsion
- Rarely upper, middle and lower plexus are involved
Post Anesthesia Brachial Plexopathy
- Follows surgical procedure; usually under general anesthesia
- Abdominal operation (usually cholecystectomy or hysterectomy)
- Usually unilateral; rarely bilateral; R = L arm
- Upper plexus > lower plexus initially. Entire plexus may be involved
- Weakness and paresthesias predominant symptoms
- Rarely painful
- Recovery begins 2–3 weeks after onset and may require several months to be complete
- Sensory loss recovers first, followed by lower plexus, then upper plexus; then motor function
- Rarely Horner's syndrome; aching in dermatomal distribution with muscle tenderness
- Malpositioning of the patient; probable traction injury of the plexus
- Positions causing post-operative paralysis:
- Supine
- Trendelenburg (steep and prolonged)
- Abduction of one or both arms to 90° or greater
- Extension and external rotation
- Rotation and lateral flexion of the head to the contralateral side
- Lower shoulder and arm compressed (lateral position)
- Flexed and prone position (back procedures); excessive and abduction and anterior arm flexion
Post Medial Sternotomy
- Middle aged and elderly patients; open heart procedures
- Sternum split vertically and retracted laterally
- Lower plexus affected; ulnar fibers are disproportionately affected (C8; APR)
- Unilateral hand weakness
- 4th/5th finger and medial forearm paresthesias
- Weakness of the lower trunk innervated fibers, damage to the C8 APR occurs
- Incidence approximately 2–5%
- May occur with cardiac transplantation
- Probable sternal injury (fracture of the proximal first rib)
- Recovers in approximately 4 months
Brachial Plexus Surgery
- Most lesions occur during transaxillary first rib resection; less frequently with scalenectomy and neurolysis
- No gender difference; young and middle aged patients are affected
- Direct surgical injury or tractions of the plexus during surgery
- Phrenic nerve may be involved concomitantly (particularly if the procedure involves the middle scalene muscle)
- Site of lesion:
- Proximal lower trunk
- Distal C8 and T1 APR
- Lower trunk usually involved (transaxillary rib resection); weakness immediately noted
- Pain is the predominant symptom and gradually increases in severity (central sensitization)
Shoulder Injuries with Concomitant Brachial Plexus Involvement
- Humeral fracture or dislocation
- Scapular fracture
- Rotator cuff tear:
- Approximately 30% of these injuries are associated with brachial plexopathy
- All components of plexus may be injured
- Axillary mononeuropathy; posterior and medial > than upper trunk and lateral cord
- Falls > MVA > direct shoulder trauma are causative
- Traction injuries (neuropraxic)
- Older patients are more susceptible
- Humeral fractures and dislocated shoulders cause ischemic or a vascular compressive lesion
- Supra and infraclavicular (trunk and cord); terminal nerve injuries occur with reduction of shoulder dislocation
- Clavicular fracture with plexopathy:
- Excess motion at fracture site
- Exuberant callus formation
- Tight figure of eight brace
- Delayed onset (months to years)
- Upper arm pain exaggerated by arm elevation
- Weakness of the extremity (division compression)
Back Pack Palsies
- Noted in military personnel and civilians using back packs; males > females
- Related to pack design and weight; multiple mechanical and time dependent features
- Possible congenital structural or prior trauma as predisposing factors
- Dominant or nondominant extremity affected
- Preceded by transient episodes prior to fully developed syndrome
- Muscle weakness and wasting of the shoulder, arm or forearm > pain; upper > middle trunk plexus innervated muscles involved; deltoid particularly involved
- Sensory loss and reflex changes occur
- EMG: conduction block > axon loss
Gunshot Wounds (Civilian)
- 85% male; average age 28 years
- 23% supraclavicular
- 77% infraclavicular
- 50% affect cords or terminal nerves
- At surgery: majority of patients have plexus in continuity
Laceration Injuries
- Caused by knives or glass (fall through glass windows); dog bites, chain saws, propeller fans
- Associated damage to blood vessels of the neck; axilla and upper lung
- 33% injuries are in continuity
- Knife or glass injury often focal
Postoperative Brachial Plexopathy
- Clinical Features:
- Clinical presentation transaxillary first rib resection:
- Weakness and wasting in lower trunk distribution
- Paraesthesias and burning pain in 4th and 5th fingers and medial forearm
- Less commonly:
- Patients awaken with flail arm, numbness and pain of the entire upper extremity
- Above pattern evolves to medial cord distribution
- Anterior Scalenectomy and Neurolysis:
- Patients awaken with pain across the trapezius ridge and down the medial scapular border
- Minimal weakness of the rhomboids, spinati, biceps
- Occasional paresthesias of lateral deltoid and lateral forearm
- Occasional weakness of ipsilateral phrenic nerve
Orthopedic Surgical Procedure
- Chronic recurrent anterior shoulder dislocation:
- Putti-Platt; Bristow procedures
- During surgery: trauma to the musculocutaneous nerve most frequent; median, ulnar, radial and axillary nerves may be injured
- Concomitant damage to the axillary artery and vein
- Delayed onset plexopathy following modified Bristow procedure:
- Bone screw that attaches the coronoid process to the glenoid rim works loose
- Axillary artery pierced, pseudo aneurysm formation that compresses infraclavicular plexus
- Shoulder joint replacement:
- Trauma to the axillary and supra scapular plexus
- Arthroscopy of the shoulder:
- Trauma to infraclavicular nerves:
- Musculocutaneous
- Axillary
- Ulnar
- Radial
- Traction injury
- Surgical procedures that compromise the costoclavicular space:
- Operations to correct Sprengel's deformity
- Midportion of clavicle surgery (fracture or to obtain access to subclavian vessels); regeneration of lateral clavicle with excess callus formation compresses the plexus
- Direct trauma from arteriography and cannulas:
- Infraclavicular trauma brachial plexopathy from:
- Cords of the plexus are adjacent to the second segment of the axillary artery; median nerve is on the surface of the artery
- Leakage of blood from the puncture site that causes direct compression of terminal nerves median > ulnar > radial
- Combination of median and ulnar nerve trauma
- Clinical symptoms:
- Pain and paresthesias
- Arm weakness in characteristic patterns
- Onset of symptoms may be delayed up to two weeks
- Nerve lesions from pressure in the medial brachial fascial compartment:
- Extends from the axilla to the elbow
- Formed by the medial intermuscular septum and surface of the medial upper arm
- Encloses the neurovascular bundle and the fascial axillary sheath
- Percutaneous cannulation of the subclavian and internal jugular vein:
- Direct instrumentation induced trauma
- Hematoma compression
- Axillary mono neuropathy (occasional)
- Upper trunk plexopathy (rare)
- Percutaneous brachial plexus block:
- Injuries may be caused by:
- The block itself
- Tourniquet induced ischemia
- Post-operative casting
- The surgical procedure
- Axillary block approach more injuries than interscalene blocks
- Usual symptoms are paresthesias in the median and ulnar nerve distributions
- Slight weakness
- May have delayed onset (up to 2 days) following the procedure
Neurovascular Brachial Plexus Injury
- General Features:
- Blood vessel and plexus may be injured simultaneously
- Brachial plexus involved by secondary ischemia
- Clinical Presentations:
- Latent period between injury and blood extravasation or pseudo aneurysm may be prolonged greater than a month
- Neurologic symptoms may progress rapidly
- Damage can extend over a long segment
- Compressed nerves may have rapid functional decline
- Pain and paresthesias are the presenting symptom
- Traumatic neurovascular injuries often compromise one or more cords
- Median and ulnar terminal nerves affected by iatrogenic injury
- Rarely neurovascular injures are due to blood dyscrasias or as a consequence of anticoagulation
Closed Brachial Plexopathy (Specific Entities)
- Recoil force of a rifle or shotguns against the clavicle:
- Coma from drugs or alcohol:
- Lower trunk/medial cord involved
- Traumatic asphyxia (crowd crush)
- Miliary brace posture:
- Upper trunk injury (usually)
- Body arm; vest restraints:
Arterial Vascular Thoracic Outlet Syndrome
- Extremely rare
- Adson's maneuver positivity much more frequently seen in neuropraxic brachial plexus injuries
- Males equal to females in incidence
- Unilateral
- Bony abnormality causes post stenotic dilatation, then aneurysm formation of the subclavian or axillary artery
- Distal emboli from thrombi in the artery to the fingers
- Ischemia of the hands and fingers
- May have severe ischemic pain
- Subgroup of patients suffer severe symptomatic ischemia of the extremity (when abducted)
Effort Venous Thrombosis of the Upper Extremity ( Paget–von Schrötter Disease)
- Thrombosis of the subclavian and axillary vein:
- Follows extreme exercise of the extremity
- Prolonged compression of axillary vein on a hard surface (arm outside window and resting on the door of a car)
- Abrupt presentation
- Upper extremity swelling, cyanosis, livedo reticularis
- Dilated venous collaterals over chest and shoulder
- Brachial plexus not involved
Unusual Causes of Direct Brachial Plexus Injury
- Transaxillary bypass
- Radical mastectomy
- Thoracic sympathectomy
- Axillary A–V fistula for renal dialysis
- Reconstruction of a bound axilla
- Biopsy of brachial plexus tumor
- Burner syndrome:
- Upper plexus may show fixed symptoms; (mild motor, sensory and reflex changes) middle and lower plexus symptoms resolve
- Young male
- Contact sports (football, wrestling)
- Burning pain that usually subsides within an hour
|