Upper limb nerve injuries

Question 1

UMN vs LMN

Answer 1

UMN- arises from motor cortex or brainstem.

LMN- arises from. the anterior horn cell.

Question 2

UMN lesions

Answer 2

Increased tone

Held in flexed posture if chronic
- Flexors stronger than extensors due to pyramidal weakness

Brisk reflexes

Sensory level

Question 3

LMN lesions

Answer 3

Muscular atrophy

Fasciculation

Flaccid tone

Weakness at myotomal or peripheral nerve distribution

Reducd reflexes

Dermatomal/ peripheral nerve sensory loss.

Question 4

C5 myotome

Answer 4

Deltoid

- Shoulder abduction

Question 5

C6 myotome

Answer 5

Elbow flexors:
Biceps
Brachialis
Brachiradialis

Question 6

C7 myotome

Answer 6

Triceps- elbow extensor

Superficial forearm extensors and flexors

Question 7

C8 myotome

Answer 7

Finger extension and flexion:

Fore arm extensors

Deep forearm flexors

Question 8

T1 myotome

Answer 8

Intrinsic hand muscles

- Finger abduction

Question 9

Biceps reflex

Answer 9

C5 reflex

- Musculocutaneous nerve

Question 10

Supinator jerk

Answer 10

C6 reflex

- Radial nerve

Question 11

Triceps jerk

Answer 11

C7 reflex

- Radial nerve

Question 12

Finger jerk

Answer 12

C8 reflex

- Median and ulnar nerve

Question 13

Avulsion

Answer 13

Tearing of the nerves from its attachment at the spinal cord

Can present with flail arm if lesion is in C5-T1

– Requires surgical repair

Question 14

Rupture nerve plexus injury

Answer 14

Tearing of the nerves but not from its attachment to the spinal cord
- Requires surgical repair

Question 15

Neuroma

Answer 15

Tumour or growth of the nerve tissue
- Can arise from the axon

Requires surgical repair

Question 16

Neurapraxia

Answer 16

Axons remain intact, but myelin damage cause an interruption of the impulse down the nerve fibre.
- Good prognosis.

Question 17

Types of brachial plexus injuries

Answer 17

Trauma

Cancer

• Infiltration (i.e pancoast tumour)
• After radiation damage

Inflammatory
- Brachial neuritis

Structura;
- Thoracic outlet syndrome

Question 18

Erb-duchenne type paralysis

Answer 18

Paralysis of the arm caused by severing of C5-6 roots.

• Seen in trauma
• Fingers unimpaired

Paresis of:

• Biceps
• Bracioradialis
• Deltoid
• Supraspinatus
• Supinator.

Arm cannot:

• Elevate
• Abduct
• Externally rotate
• Flex at elbow

Question 19

Klumpke Paralysis

Answer 19

Partial paralysis of the lower roots of the brachial plexus (C8-T1)–> affects median and ulnar nerves

• Paralysis of intrinsic hand muscles
• Weakness of shoulder/arm muscles
• Unable to flex wrist of fingers
• Sensory loss of hand and medial forearm

Claw hand

Question 20

Pancoast tumour

Answer 20

Lung tumour that can infiltrate the Lower brachial plexus

Symptoms

• Pain in shoulder girdle and inner arm
• Ipisilateral horners syndrome (sympathetic nerve damage)

Question 21

Radiation induced brachial plexopathy

Answer 21

Typically around 6 years post-radiation

• Tends to affect upper brachial plexus
• Not always presenting with pain

Associated with breast, lung cancer and lymphoma

Question 22

Parsonage – Turner Syndrome

Answer 22

Idiopathic brachial neuritis

Symptoms

• Sever pain over days
• Weakness and wasting follows after pain diminishes

Features

• Monophasic
• Mainly unilateral
• Thickening and enhancement in MRi

Treatment

• Analgesia
• Physiotherapy

Question 23

Thoracic outlet syndrome

Answer 23

Compression around thoracic inlet.

Sites:

• Between anterior and middle scalene muscles
• Under clavicle in cost-clavicular space
• Beneath tendon of Pec.minor

Can be neurogenic or vascular

Question 24

Neurogenic Thoracic outlet syndrome

Answer 24

Compression of nerve at thoracic inlet.
- Mainly affects median nerve

Symptoms

• Parethesia/ numbest/ weakness
• Aggravated by elevation or sustained use of hand/arms.

Question 25

Vascular Thoracic outlet syndrome

Answer 25

Compression of vessel at high rib
- Causes stenosis with a post-stenotic dilation.

Symptoms
- Forearm fatigue with mins of use

Signs

• Oedema and cyanosis
• Collateral venous patterning over ipsilateral shoulder/ chest wall/ neck.
• Low BP on affected arm, diminished distal pulses.

Question 26

Winged scapula

Answer 26

Caused by injury to long thoracic nerve–> paralysis of serrates anterior

• Blow/ pressure in posterior triangle of the neck
• Radical mastectomy

Question 27

Median nerve innervation

LOAF

Answer 27

Lateral 2 lumbricals

Thenar muscles:
Opponens pollicus

Abduction pollicus brevis

Flexor policus brevis

Question 28

Carpal tunnel syndrome causes

Answer 28

Diabetes

Pregnancy

Hypothyroidism

Rheumatoid arthritis

Repetitive strain

Wrist fracture.

Question 29

Anterior interosseous nerve syndrome

Answer 29

From median nerve
- Below elbow

Prone to compression by pronator trees.

Signs

• Flexor policis longus weakness
• Weakness in FGP
• Weak pronation

Causes:

• Prolonged use of screwdriver (gripping tightly with forced pronation)
• Careless blood taking

Question 30

Ulnar lesions

Answer 30

Higher lesion in upper limb

• Paralysis of ulnar half of FGP
• Interossei and lumbrical paralysis
• No claw

Lesion at the wrist

• Intact FDP
• Flexion of DIP and PIP (paralysis of interossei)
• Hyperextension at the MCP (paralysis of lumbricals)

Question 31

Froment’s sign

Answer 31

Test for palsy of the ulnar nerve

- Especially the action of adductor pollicis.

Question 32

Saturday night palsy

Answer 32

Wrist drop
- Inability to extend the wrist due to radial nerve palsy

Rarely causes sensory loss due to extensive overlap with median nerve (XC anatomical snuff box)

Question 33

Axonal vs demyelination nerve conduction study (NCS)

Answer 33

NCS determines amplitude and velocity of peripheral nerve

Axonal loss
- Decrease in amplitude

Demyelination
- Decreased velocity (speed)

Question 34

Needle EMG

Answer 34

Measures electrical activity of muscle during voluntary contract.

The pattern can predict if a lesion is neurogenic or myopathic