Case 62 Adult Brachial Plexus Injury

Timothy Fei and Kyle Chepla

Unilateral loss of upper extremity sensation with biceps and shoulder weakness after high-energy injury and concern for upper brachial plexus injury (C5–C6)
Clinical photograph demonstrates left-sided wasting of the deltoid and biceps with preserved triceps and wrist extensors; patient is unable to abduct and externally rotate his shoulder or flex his elbow

Mechanism of injury: Penetrating (e.g., sharp laceration or gunshot) versus traction; high-energy versus low-energy injury
Time since the injury occurred
Age and hand dominance
Occupation and hobbies
Previous upper extremity injury or surgery
Any previous work-up of the injury

Critical to take a full inventory of sensory and motor deficits
- Localizes level of injury and helps in guiding treatment plan
Evaluate and grade motor function: British Medical Research Council (MRC) scale for muscle strength (see Table 62-1) of all muscles innervated by the brachial plexus (see Fig. 62-1)
Evaluate sensory function: Dermatome distribution and two-point discrimination (2PD) in fingers
Joint mobility: Passive range of motion at shoulder, elbow, wrist, hand, and fingers
Vascular status: Pulses and capillary refill to evaluate for associated arterial injury (10–25% incidence)
Evaluate for Horner’s syndrome (ptosis, anhidrosis, and miosis) which indicates a preganglionic injury involving the sympathetic chain
Assess for common associated bony fractures: Cervical fracture, clavicle fracture, rib fracture, scapula fracture, and shoulder dislocation

Fig. 62.1 Brachial plexus anatomy. For reference (do not memorize).

Table 62.1 British Medical Research Council Motor Grading Scale
Grade	Exam findings
0	No muscle contraction
1	Visible muscle contraction, but no movement
2	Visible muscle contraction, active movement in plane, with gravity eliminated
3	Active movement against gravity, but not against resistance
4	Active movement against strong resistance, but not full strength
5	Active movement, with full strength