Brachial plexus examination

How to approach brachial plexus examination in FRCS(Orth/Plast)?

General advice

Examining a patient with brachial plexus injury may appear as a daunting task and this is made worse by being watched and questioned at the same time. Whilst there are over 50 named muscles to be tested, it is not practical (and there is not enough time in FRCS exam) to allow you to examine every single muscle in the upper limb. You then have to rely on pattern recognition.

The challenge lies in localisation of the lesion. This can only be achieved by having a thorough understanding of the anatomy of the brachial plexus. The extent, level, severity and chronicity of a brachial plexus injury will determine the physical signs that are manifested. Patients who have had reconstructive surgery (i.e. have scars) may present greater challenges during examination as they may have variable degree of recovery.

A potential pitfall in candidates is the desire to arrive at a specific diagnosis right at the start. However it is more important to demonstrate your logical thinking and examination techniques during the examination.

Top Tips

• Have a quick glance at the hand which would give you clues as to whether this is partial palsy (good hand) or total palsy (poor hand).
   
• A totally flail arm and hand represent total palsy.
   

An examiner’s favourite - Is it a pre-ganglionic or post-ganglionic lesion?

The following are clues to a pre-ganglionic injury that you may identify and mention to the examiners in order to demonstrate your higher order thinking:

• Horner's syndrome
  • Partial ptosis of the upper eyelid
  • Miosis (constricted pupil)
  • Anhidrosis (loss of sweating on one half of the face)
  • Enophthalmos (eye appears sunken)
     
• The T1 root lies close to the T1 sympathetic ganglion. Evidence of injury to the T1 sympathetic chain as evidenced by a Horner’s syndrome would infer that the T1 root has probably been injured.
   
• If rhomboids or serratus anterior are weak then a pre-ganglionic injury should be suspected.
   
• If chest X-ray is shown, look for elevated (paralysed) hemi-diaphragm (phrenic nerve palsy C3,4,5).
   
• Fractures of the transverse processes of the cervical vertebrae or a fractured first rib indicate a high-energy injury with likely intradural injury of the lower two roots.
   
• Scapulothoracic dissociation is often associated with root avulsion and major vascular injury.
   

Suggested Sequence of Clinical Examination

(You may be requested to demonstrate part of the whole sequence only)

• Inspection
  • Best to start with the patient stood with both arms and torso exposed.
  • Look at the face for Horner's syndrome
  • Look for surgical scars
  • Comment on muscle wasting – shoulder girdle, arm, forearm or hand
  • Comment on the resting posture of the limb
     
• Exclude fixed contractures by gentle passive movements.
   
• Motor testing
  • Requires knowledge of the Medical Research Council (MRC) grading
    • 0 – No Contraction
    • 1 – Flicker
    • 2 – Active motion (gravity eliminated)
    • 3 – Active motion (against gravity only)
    • 4 – Acitve motion (against resistance)
    • 5 – Normal power
       
  • If a muscle is weak, repeat testing in the horizontal plane in order to eliminate gravity eg abducting the shoulder to test elbow flexion/extension power.
     
  • Muscle testing is an active process involving
    • Look (for contraction and movement of the limb)
    • Feel (for contracted muscle/tendon)
    • Move (to test resistance)
       
  • Be systematic. Start proximally and work distally
    
        Standing from the back
     
    • Trapezius (spinal accessory - XI, C3,4)
      • Can you shrug your shoulders
    • Rhomboids (dorsal scapular nerve – C4,5)
      • Push your shoulder blades together
    • Serratus anterior (long thoracic nerve - C5,6,7)
      • The classic test is wall-press test.
      • In BPI, the patient may be unable to lift the arm.
      • The arm should be supported by the examiner with one hand and the patient asked to push forward as if trying to open a door. At the same time the examiner should hold the lower pole of the scapula with another hand.
    • Latissimus dorsi (thoracodorsal nerve – C6,7,8)
      • While the arm is supported in a flexed position, ask the patient to push down (while the examiner palpates for musle contraction).
    • Deltoids (axillary nerve – C5,6)
      • Extend, abduct and flex the shoulder to test the posterior, middle and anterior parts respectively (unless the muscle is clearly wasted).
      • Demonstrate specific signs (if isolated nerve palsy suspected):
        • Swallow-tail sign
          • The patient is asked to extend the shoulder while bending the trunk forward. A result of 20˚ or greater of extension lag relative to the normal side indicates a positive sign.
        • Abduction internal rotation
          • Actively and maximally abduct the shoulder in internal rotation with the elbow flexed. Abduction lag relative to the normal side indicates a positive sign.
    
        Standing from the front
  • • Pectoralis major (lateral and medial pectoral nerves)
      • Clavicular head (C5,6)
        • Atrophy would imply lateral cord injury.
        • Ask the patient to touch their contralateral shoulder (and the examiner palpates for evidence of contraction).
      • Sternocostal head (C7,8,T1)
        • Atrophy would imply medial cord injury.
        • Ask the patient to push against the hip (and the examiner palpates the axillary fold).
           
    • Rotator cuffs
      • Supraspinatus (suprascapular nerve - C5,6)
        • Test shoulder abduction in the scapular plane with the thumb pointing downwards.
      • Infraspinatus (suprascapular nerve - C5,6)
        • Test external rotation with the shoulder in adduction and the elbow flexed.
      • Teres minor (axillary nerve – C5,6)
        • Test external rotation with the shoulder in abduction and the elbow flexed.
      • Subscapularis (upper and lower subscapular nerves – C5,6,7)
        • Belly-press sign. Ask the patient to bring the elbows forward while pressing the belly. A flexed wrist relative to the normal side indicates a positive sign.
           
      Next, proceed with the following composite testings to demonstrate the myotomes (levels) involved (accept some degree of variability):
       
    • Elbow flexion (C5,6)
       
    • Elbow extension (C7,8)
       
    • Forearm supination (C6)
       
    • Forearm pronation (C7,8)
       
    • Wrist flexion/extension (C6,7)
       
    • MCPJ flexion/extension (C7,8)
       
    • Grip (C8)
       
    • Fingers abduction (T1)
       
• Sensory testing
  • Establish normal sensation in an uninjured area (such as forehead or sternum).
  • First, assess the dermatomes (C5-lateral elbow; C6-thumb tip; C7-middle finger tip; C8-little finger tip; T1-medial elbow) and then if necessary such as in infraclavicular BPI, examine according to the terminal branch distribution.
     
• Check for Tinel's signs (and take note of the dermatomal distribution).
   
• Palpate for the radial pulse and check the reflexes.