T2 L7: Injuries of the upper limb

Question 1

What is the difference between a upper and lower motor neurone?

Answer 1

Upper motor neurones originate in the cerebral cortex

Lower motor neurone originate in the spinal cord

Question 2

What is the difference in symptoms of lower and upper motor neurone disease?

Answer 2

Upper motor neurons are responsible for motor movement, whereas lower motor neurons prevent excessive muscle movement.

Upper motor disorders usually cause spasticity; lower motor disorders usually cause flaccidity

Question 3

What are myotomes?

Answer 3

The relationship between muscles and the spinal cord

Question 4

What are the myotomes of the upper limb?

Answer 4

C5: Deltoid (musculoskeletal nerve)
C6: Biceps, brachialis, brachioradialis (radial nerve)
C7: Triceps, superficial forearm extensors and flexors (radial nerve)
C8: Forearm extensors, deep forearm flexors (median and ulnar nerve)
T1: Intrinsic hand muscles

Question 5

What is avulsion?

Answer 5

When the nerve is pulled off the cord

Question 6

What is a neuroma?

Answer 6

A lesion on the nerve that causes compression

Question 7

What is neuropraxia?

Answer 7

Stretching of the nerve that damages myelin and causes conduction problems

Question 8

What can cause brachial plexus injury?

Answer 8

Trauma

• Erb-Duchenne type paralysis: avulsion of C5,C6 roots
• Klumpke paralysis: avulsion of C8, T1 roots

Cancer

• Lung cancer: Pancoasts tumour
• Radiotherapy

Inflammation
-Brachial neuritis

Structural
-Thoracic outlet syndrome

Question 9

What is structural outlet syndrome?

Answer 9

Caused by a narrowing of the thoracic outlet at the shoulder

There are variations in anatomy that causes compression sites: between anterior and middle scalene muscles, beneath clavicle in the costoclavicular space, beneath tendon of pectoralis minor

Question 10

What is Erbs palsy?

Answer 10

Upper plexus palsy affecting C5/C6 innervated muscles

It’s caused when the upper brachial plexus roots are torn during birth complications or a blow to the shoulder in adults

Symptoms: weak muscles including biceps, brachioradialis, deltoid, supraspinatus, supinator

Fingers are unimpaired but the arm doesn’t work

Question 11

What is Klumpske’s palsy?

Answer 11

Causes the arm to work but not the hand

Caused when you clutch for an object while falling which causes inferior trunk plexus injury involving C8/T1

Symptoms: patient is unable to flex wrist or fingers, there is weakness of all small muscles of the hand, and there is sensory loss to hand and inner border to forearm

Question 12

What is Horner’s syndrome?

Answer 12

A condition that affects the face and eye on one side of the body

It’s caused by the disruption of a nerve pathway from the brain to the head and neck

Question 13

What is a Pancoast tumour?

Answer 13

Cancers that start at the apex of the lung that infiltrates the lower brachial plexus

It causes ipsilateral Horner’s syndrome

Question 14

What is radiation induced brachial plexopathy?

Answer 14

Usually presents about 6 years after radiation that causes injury to the brachial plexus

Question 15

What is idiopathic brachial neuritis?

Answer 15

Begins as pain over days and as pain diminishes, it’s followed by weakness and wasting rarely bilateral

An MRI would show thickening and enhancement

The patients get better by themselves. Analgesia and physiotherapy are provided

Question 16

What is the difference between neurogenic and vascular thoracic outlet syndrome?

Answer 16

Neurogenic

• Paraesthesia, numbness, weakness
• Not localised to specific nerve distribution
• Aggravated by elevation or sustained use of arms and legs

Vascular

• Forearm fatigue within minutes if use
• Swelling and cyanosis
• collateral venous patterning over the ipsilateral shoulder, chest wall, and neck
• Rarely pain, pallor, and coldness
• Lower BP on affected arm and diminished distal pulse

Question 17

What is paraesthesia?

Answer 17

Burning or prickling sensation in arms and legs

Question 18

How can the long thoracic nerve be injured?

Answer 18

By blows or pressure in the posterior triangle of the neck or during a radical mastectomy

Question 19

What is the function of the long thoracic nerve?

Answer 19

It supplies the serratus anterior muscle.

Impairment of this nerve causes winging of the scapula because the serratus anterior can’t pull the medial border of the scapula to the posterior thoracic wall to stabilise it there

Question 20

What are the 2 most common sites of compression of the median nerve?

Answer 20

The wrist (carpal tunnel syndrome)
Elbow

Question 21

Which hand muscles are innervated by the median nerve?

Answer 21

LOAF

Lateral 2 lumbricals
Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis

Question 22

What are the causes of carpal tunnel syndrome?

Answer 22

Diabetes
Pregnancy (general swelling)
Hypothyroidism
Rheumatoid arthritis
Repetitive strain (due to occupation)
Wrist fractures

Question 23

What are the 2 tests used to look for carpal tunnel syndrome?

Answer 23

Tinel’s test
-Tap over the carpal tunnel along the wrist

Phalen’s test
-Inverted prayer and hold the wrists together for 1min

Positive test for both is if tingling is felt in the thumb and lateral 3.5 digits (where the nerve supplies)

Question 24

What is anterior interosseous nerve syndrome?

Answer 24

Motor branch of the median nerve only affected

Causes weakness in flexor pollicis longus, flexor digitorum profundus and pronator quadratus muscle in the forearm

Causes weakness of the thumb joint, digit joint, and weakness on pronation

Question 25

What is ulnar palsy at the elbow?

Answer 25

Compression of the ulnar nerve as it passes through the elbow

Causes an ‘ulnar claw’

Question 26

What is Froment’s sign?

Answer 26

Grabbing a piece of paper between the thumb and index finger

Weakness indicates ulnar nerve palsy

Question 27

What is meant by Saturday night palsy?

Answer 27

Radial nerve palsy caused when people fall asleep in a chair with their arm over it after drinking and this compresses the radial nerve at the elbow

Question 28

Why are nerve conduction studies useful?

Answer 28

They determine amplitude and velocity of the peripheral nerve

Axonal loss causes decrease in amplitude
Demyelination causes decrease in velocity