Upper limb nerve injuries

Question 1

UMN in the upper limb

Answer 1

Held in flexed posture if chronic

Increased tone

Pyramidal weakness (flexor muscles stronger than extensors)

Brisk reflexes

Sensory level

Question 2

LMN in the upper limb

Answer 2

Wasting/ fasciculations

Flaccid tone

Weakness in either a myotomal distribution or a peripheral nerve distribution

Reduced reflexes

Dermatomal or peripheral nerve distribution of sensory loss

Question 3

3 anatomical regions for localising lesions

Answer 3

Roots

Brachial plexus

Peripheral nerve

Question 4

Myotomes

Answer 4

Relationship between the spinal nerve and muscle

Question 5

Dermatomes

Answer 5

Relationship between the spinal nerve and skin

Question 6

Roots and myotomes

Answer 6

C5- deltoid; shoulder abduction

C6- biceps, brachialis, brachioradialis; elbow flexion

C7- triceps, superficial forearm extensors, superficial forearm flexors; elbow extension, wrist extension, wrist flexion

C8- forearm extensors, deep forearm flexors; finger extension, finger flexion

T1- intrinsic hand muscles; finger abduction

Question 7

Biceps reflex

Answer 7

C5 reflex conveyed through the musculocutaneous nerve

Question 8

Supinator jerk

Answer 8

C6 reflex conveyed through the radial nerve

Question 9

Triceps jerk

Answer 9

C7 reflex conveyed through the radial nerve

Question 10

Finger jerk

Answer 10

C8 reflex conveyed through the median and ulnar nerve

Question 11

Reflex in LMN lesions

Answer 11

Depressed

Question 12

Brachial plexus injury

Answer 12

Trauma

• erb-duchenne type paralysis: avulsion of C5, C6 roots
• klumpke paralysis: avulsion of C8, T1 roots

Cancer

• lung cancer: pancoasts tumour
• radiotherapy

Inflammatory
- brachial neuritis

Structural
- thoracic outlet syndrome

Question 13

Erbs palsy

Answer 13

Upper plexus palsy

C5/6 innervated muscles

Weak muscles include

• biceps
• brachioradialis
• deltoid
• supraspinatus
• supinator

Question 14

Klumpke’s palsy

Answer 14

Clutching for an object with falling from a height
- inferior trunk plexus injury involving C8/T1

Involves trunk that supplies median and ulnar nerves

Unable to flex wrist or fingers

Weakness of small muscles of the hand

Sensory loss hand and inner border of forearm

May lead to a claw hand

Arm works but hand does not

Question 15

Metatastic brachial plexopathy

Answer 15

Pancoast tumour (lung)- infiltration of the lower brachial plexus

Pain in shoulder girdle and inner arm

Ipsilateral horners syndrome

Question 16

Radiation induced brachial plexopathy

Answer 16

Mean 6 years post radiation

Associated with treatment for breast, lung cancer and lymphoma

Pain is not a consistent feature

Predilection for upper brachial plexus

Question 17

Idiopathic brachial neuritis

Answer 17

Aetiology not clear, infectious, post infectious

Severe pain over days; as pain diminishes, it is followed by weakness and wasting

Typically monophasic

Rarely bilateral

MRI shows thickening and enhancement

NCS/ EMG is useful for prognostication

Treatment

• analgesia, physiotherapy
• limited evidence for the use of steroids

Question 18

Thoracic outlet syndrome

Answer 18

Variations in anatomy cause compression sites:

• between anterior and middle scalene muscles
• beneath clavicle in the costoclavicular space
• beneath tendon of pectoralis minor

Question 19

Thoracic outlet syndrome: neurogenic

Answer 19

Paresthesia, numbness, weakness

Not localised to spcific nerve distribution

Reproducibly aggravated by elevation or sustained use of arms or hands

Question 20

Thoracic outlet syndrome: vascular

Answer 20

Forearm fatigue within minutes of use

Swelling and cyanosis

Collateral venous patterning over the ipsilateral shoulder, chest wall and neck

Rarely pain, pallor and coldness (arterial involvement)

Lower BP on affected arm, diminished distal pulses

Question 21

2 common sites of compression of the median nerve

Answer 21

Wrist (carpel tunnel syndrome)

Elbow

Question 22

Median nerve innervated hand muscles

Answer 22

L- lateral 2 lumbricals
O- opponens pollicis
A- abductor pollicis brevis
F- flexor pollicis brevis

Question 23

Causes of carpal tunnel syndrome

Answer 23

Diabetes

Pregnancy

Hypothyroidism

Rheumatoid arthritis

Repetitive strain

Question 24

Anterior interosseous nerve

Answer 24

Arises from median nerve just above elbow

Prone to compression between 2 heads of pronator teres muscle

Gripping tightly with forced pronation

May also be damaged in careless blood taking

Question 25

Anterior interosseous nerve syndrome

Answer 25

Pure motor branch of the median nerve

Weakness in flexors of ip joint of thumb (flexor pollicis longus) and dip joints of index and middle fingers (flexor digitorum profundus) weakness of pronation

Question 26

Higher lesion in the upper limb

Answer 26

Paralysis of the ulnar half of the flexor digitorum profundus, interossei and lumbricals

The ring and little fingers are not flexed and there is no claw

Question 27

Lesion at the wrist

Answer 27

Flexion at the DIP (FDP)

Flexion at the PIP (interossei are paralysed)

Hyperextension at the MCP (lubricals are paralysed)

Question 28

Long thoracic nerve

Answer 28

May be injured by blows or pressure in the posterior triangle of the neck or during radical mastectomy

Leading to winged scapula

Supplies the serratus anterior muscle