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Brachial Plexus Injury: Anatomy, Types, Pathology & Physiotherapy Assessment

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Part 1: Anatomy of the Brachial Plexus

1.1 Roots (C5-T1)

• Anterior rami of C5, C6, C7, C8, T1
• Receive gray rami communicantes from the sympathetic trunk
• Pass between anterior and middle scalene muscles posterior to the subclavian artery
• Branches from the roots: Dorsal scapular nerve (C5) - rhomboids & levator scapulae; Long thoracic nerve (C5-7) - serratus anterior; Contribution to phrenic nerve (C5)

1.2 Trunks

• Branch from superior trunk: Suprascapular nerve (supraspinatus, infraspinatus), Nerve to subclavius
• The inferior trunk lies on rib I posterior to the subclavian artery

1.3 Divisions

• Anterior divisions supply flexor (anterior) compartments
• Posterior divisions supply extensor (posterior) compartments
• No peripheral nerves arise directly from the divisions

1.4 Cords (named by relationship to axillary artery)

1.5 Major Terminal Branches

• Musculocutaneous nerve (C5-7) - biceps, brachialis, coracobrachialis; lateral cutaneous forearm
• Median nerve (C5-T1) - flexors of wrist/fingers, thenar muscles; sensory over radial 3.5 fingers
• Ulnar nerve (C8-T1) - intrinsic hand muscles; sensory over ulnar 1.5 fingers
• Radial nerve (C5-T1) - extensors of wrist/fingers; posterior arm/forearm sensation
• Axillary nerve (C5-6) - deltoid, teres minor; lateral arm sensation

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Part 2: Types and Classification of Brachial Plexus Injury

2.1 Seddon & Sunderland Classification (Pathological Basis)

• Neuropraxia - most common after mild traction or compression (e.g., "stinger" in sport)
• Axonotmesis - crush, traction injuries; Wallerian degeneration occurs distal to injury site
• Neurotmesis - complete transection; surgical repair required

Key: Fibrillations and fasciculations on EMG appear at 14+ days after injury (not before). Order EMG at 3 weeks post-closed injury to distinguish neuropraxia from more severe injuries. - Sabiston Textbook of Surgery

2.2 Anatomical / Level Classification

A. By Level of Injury

B. By Clinical Pattern (Nerve Root Level)

• Most common - birth trauma with excessive lateral neck-shoulder traction; motorcycle accidents
• Motor loss: shoulder abduction (deltoid), external rotation, elbow flexion (biceps), supination, wrist extension
• Classic posture: "Waiter's tip" - arm adducted & internally rotated, elbow extended, wrist flexed, forearm pronated
• Sensory loss: lateral arm, lateral forearm (musculocutaneous), thumb
• Reflexes: absent biceps (C5) and brachioradialis (C6)
• Sensation: C5-C6 dermatomes

• Rare; excessive arm abduction (traction injury with arm overhead)
• Motor loss: intrinsic hand muscles (interossei, hypothenar, thenar), wrist flexors
• Sensory loss: medial forearm, ulnar hand and digits
• Associated: Horner syndrome (ptosis, miosis, anhidrosis, enophthalmos) if T1 preganglionic injured → sympathetic chain disruption
• Reflexes: absent finger flexor reflex

• Complete flail limb with global sensory loss
• Worst prognosis
• Often associated with avulsion injuries; Horner syndrome common

• Isolated C7: weakness of elbow extension (triceps), wrist extension, finger extension; less common in isolation

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Part 3: Pathology and Mechanisms

3.1 Etiology

• Traction/stretch - most common; motorcycle accidents, fall on shoulder (downward traction), shoulder dystocia in obstetric injury (Erb's palsy)
• Compression - tumors (e.g., Pancoast tumor), hematoma, post-irradiation
• Direct trauma - stab wounds, gunshot injuries, clavicle fractures, shoulder dislocation
• Obstetric injury - large-for-dates baby, shoulder dystocia, instrumental delivery
• "Stinger/Burner" - sports injury, transient unilateral neuropraxia; burning pain radiating down the arm

3.2 Pathological Changes

• Wallerian degeneration occurs distal to the injury site within 48-72 hours
• Schwann cells proliferate and form Bands of Büngner to guide regenerating axons
• Axonal regeneration proceeds at approximately 1-4 mm/day
• Prolonged denervation leads to irreversible muscle fibrosis (>12-18 months)
• Fibrillations/fasciculations appear on EMG at ~14 days post-injury

3.3 Preganglionic vs Postganglionic Distinctions

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Part 4: Physiotherapy Assessment (PG-Level - Comprehensive)

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4.1 Subjective Assessment (History)

• Mechanism of injury (traction, compression, penetrating, birth)
• Time since injury (acute <3 weeks vs. subacute/chronic)
• Onset: sudden vs. gradual (tumor compression is gradual)
• Dominant hand
• Occupation and functional demands
• Presence and character of pain: burning/neuropathic, shooting, constant vs. episodic
• Numbness, tingling (paraesthesia), hypersensitivity
• Prior treatments, surgeries

• Signs of spinal cord involvement (bilateral symptoms, bladder/bowel changes)
• Horner syndrome symptoms (ptosis, unequal pupils)
• Signs of vascular injury

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4.2 Objective Assessment - Positive Findings & Tests

A. Observation / Inspection

B. Anthropometric / Girth Measurement

• Circumferential measurements of arm and forearm (bilaterally) to quantify atrophy

C. Range of Motion (ROM) Assessment

• Passive ROM (PROM) and Active ROM (AROM) measured by goniometry at:
  • Shoulder: flexion, abduction, ER/IR, horizontal adduction
  • Elbow: flexion/extension, supination/pronation
  • Wrist: flexion/extension, radial/ulnar deviation
  • Fingers and thumb: all joints
• Compare bilaterally; document contractures

D. Manual Muscle Testing (MMT) - Oxford/MRC Scale

• Erb's (C5-C6): Grade 0-1 deltoid, biceps; Grade 0-1 supraspinatus; wrist/hand muscles relatively spared
• Klumpke's (C8-T1): Intrinsic hand paralysis; positive Froment's sign (thumb IP flexion during lateral pinch); clawing of ring and little fingers
• Pan-plexus: All muscles Grade 0-2

E. Sensory Assessment

• C5: Lateral arm (over deltoid)
• C6: Lateral forearm, thumb, index finger
• C7: Middle finger
• C8: Ring/little finger, medial forearm
• T1: Medial arm

F. Reflex Testing

G. Special Clinical Tests

H. Functional Assessment Tests & Outcome Measures

I. Electrodiagnostic Studies (Ordered/Interpreted by Physiotherapist in collaboration)

J. Imaging (Relevant to Physiotherapy Assessment)

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4.3 Physiotherapy Findings Summary by Injury Level

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4.4 Assessment of Specific Functional Deficits

• Neuropathic pain is common even with avulsion injuries - burning, allodynia, hyperalgesia
• Use VAS/NRS for intensity; DN4 questionnaire for neuropathic character

• Volumetric measurement or figure-of-8 taping technique
• Dependent oedema from flail limb

• Scoliosis, cervical posture (C-spine involvement)
• Shoulder girdle position
• Winging of scapula (long thoracic nerve)

• Antalgic posture, arm swing asymmetry

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4.5 Differential Diagnosis (Assessment Considerations)

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Part 5: Rehabilitation Goals (PG-Level Framework)

• Pain management (TENS, splinting, gentle positioning)
• Prevent contractures - PROM exercises
• Sensory re-education begins
• Oedema management

• Progressive active-assisted ROM as innervation returns
• Splinting (dynamic/static to prevent deformity - e.g., cock-up splint for wrist drop)
• EMG biofeedback for motor re-education
• Proprioceptive neuromuscular facilitation (PNF) techniques
• Sensory re-education

• Task-specific functional training
• Strengthening (progressive resistance)
• Compensatory strategies
• Vocational rehabilitation
• Outcome measures re-administered (DASH, VAS, grip strength)

Sources: Gray's Anatomy for Students (p. 858-859); Miller's Review of Orthopaedics 9th Ed (p. 155-156); Sabiston Textbook of Surgery (p. 807); Bradley and Daroff's Neurology in Clinical Practice (p. 2870); Campbell's Operative Orthopaedics 15th Ed 2026; Frontiers in Neurology - Review of Rehabilitation Protocols for BPI (2023)