Brachial Plexus Injuries

Brachial Plexus Injuries

Anatomy and Structure

• Origin: Brachial plexus originates from C5-C8 and T1 spinal nerve roots
• Organization: Complex network of nerves that provides innervation to the upper extremity

Mechanisms of Injury

• Compression: External pressure on the plexus
• Stretch/Traction: Forces that pull the nerve roots
• Laceration: Sharp or penetrating injuries
• Avulsion: Tearing of nerve roots from spinal cord

Etiology

• Traumatic injuries:
  • High-speed vehicular accidents
  • Stab or gunshot wounds
  • Severe shoulder trauma
• Obstetric injuries:
  • Difficult delivery procedures
  • Shoulder dystocia complications
• Compression causes:
  • Growing tumors (e.g., Pancoast tumor)
  • Chronic pressure syndromes

Classification and Types

Injury Severity Patterns

• Overstretching injuries:
  • Nerve roots remain intact
  • May involve intact axons (neuropraxia) or cut axons (axonotmesis)
• Rupture injuries:
  • Nerve roots stretched and partially torn
  • Mixed recovery potential depending on severity
• Avulsion injuries:
  • Nerve roots pulled out from spinal cord
  • No chance for spontaneous recovery

Prognosis by Injury Type

Injury Type	Recovery Prognosis	Clinical Course
Neuropraxia	Excellent	Complete recovery expected
Axonotmesis	Moderate	Good but may have residual deficits
Neurotmesis/Avulsion	Poor	Very limited recovery without surgery

Source: www.humankinetics.com

Source: en.wikipedia.org

Brachial Plexus Palsy Syndromes

Obstetric Brachial Plexus Palsy

Epidemiology:

• Occurs in <1% of live births
• Most commonly associated with shoulder dystocia during delivery
• Risk factors include large birth weight and difficult delivery

Pathophysiology:

• Baby’s shoulder becomes impacted on mother’s pubic bone
• Brachial plexus nerves undergo stretch or tear injuries
• Injury severity depends on traction forces and duration

Clinical Patterns

Three main patterns of brachial plexus palsy:

1. Upper Root Injury (Erb’s Palsy):

   • Roots involved: C5-C6 (sometimes C7)
   • Typical scenario: Overweight babies with shoulder dystocia
   • Clinical presentation: “Waiter tip position”

2. Lower Root Injury (Klumpke’s Palsy):

   • Roots involved: C8-T1
   • Typical scenario: Breech delivery of smaller babies
   • Clinical presentation: Intrinsic hand muscle weakness

3. Total Plexus Injury:

   • Roots involved: C5-T1 (entire plexus)
   • Most severe form with complete upper extremity dysfunction

Erb’s Palsy (Upper Root Injury)

Nerve Roots Involved:

• Primary: C5-C6
• May extend to: C7 in more severe cases

Muscle Groups Affected:

• Shoulder abductors (deltoid, supraspinatus)
• Shoulder external rotators (infraspinatus, teres minor)
• Elbow flexors (biceps brachii, brachialis)
• Supinators (supinator, biceps)

Clinical Presentation:

• Classic “Waiter Tip Position”:
  • Arm held adducted to the side
  • Internally rotated shoulder
  • Extended elbow
  • Pronated forearm
• Motor function: Weakness in shoulder abduction and elbow flexion
• Sensory function: Usually preserved over lateral arm

Klumpke’s Palsy (Lower Root Injury)

Nerve Roots Involved:

• Primary: C8-T1
• Affects: Ulnar and median nerve distribution

Mechanisms of Injury:

• Traction injuries from excessive arm abduction
• Common causes:
  • Falls from height with arm outstretched
  • Cervical rib anatomical variant
  • Violent upward traction

Motor Manifestations:

• Intrinsic hand muscles: Complete paralysis
• Wrist flexors: Variable weakness
• Fine motor skills: Severely compromised

Sensory Manifestations:

• Distribution: Loss along medial forearm and hand
• Key areas: Medial arm, medial forearm, little finger side of hand

Characteristic Deformity:

• Claw hand deformity:
  • Extended MCP joints
  • Flexed IP joints
  • Prominent metacarpal heads
  • Ulnar deviation

Total Plexus Injury

Clinical Features:

• Complete flail limb: No active movement in entire upper extremity
• Skin changes: Pale, cool extremity due to loss of sympathetic tone
• Complete sensory loss: No sensation throughout the arm
• Motor paralysis: All muscles of upper extremity affected

Associated Findings:

• Horner’s syndrome (indicative of proximal root avulsion):
  • Ptosis: Drooping of upper eyelid
  • Miosis: Constriction of pupil
  • Enophthalmos: Sunken appearance of eyeball
  • Anhydrosis: Absence of sweating on affected side

Source: www.riversideonline.com