Mononeuropathies

Question 1

Name the common nerves which are affected by neuropatheis?

Answer 1

Radial nerve
Ulnar nerve
Median nerve (and anterior interosseous nerve)
Common peroneal nerve
Femoral nerve

Question 2

What are the main nerves given off by the brachial plexus?

Answer 2

Musclocutaneous nerve
Axillary nerve
Median
Radial 
Ulnar

Question 3

What is the most common cause of radial nerve palsy?

Answer 3

Saturday night palsy (pressure on the underside of the arm, causing entrapment of the nerve in the spiral groove)

Question 4

What is the function of the radial nerve?

Answer 4

Motor
- extends wrist and fingers
- tennis backhand 
Sensory
- area over the anatomical snuffbox

Question 5

What are the presenting symptoms of a radial nerve palsy?

Answer 5

Wrist and finger drop

Numbness - usually painless

Question 6

Describe the pattern of motor weakness in radial nerve palsy.

Answer 6

Wrist extension weakness - extensor carpi radialis longus
Finger extension weakness - extensor digitorum communis
Elbow flexion in mid-pronation - brachioradialis

Question 7

What is the most common cause of ulnar nerve palsy?

Answer 7

Entrapment of the nerve at the ulnar groove (medial epicondyle of the humerus)
- caused by inflammation of lifestyle chanegs

Question 8

What is the function of the ulnar nerve?

Answer 8

Motor
- intrinsic muscles of the hand
- some muscles of the forearm 
Sensory
- medial aspect of the hand

Question 9

What are the presenting symptoms of ulnar nerve palsy?

Answer 9

History of trauma at the elbow
- repeated trauma causes permanent damage
Sensory disturbance 
Weak grip
Painless

Question 10

Describe the pattern of motor weakness in ulnar nerve palsy.

Answer 10

Weakness in the following actions

• index finger abduction (1st dorsal interosseus)
• pinkie abduction (abductor digiti minimi)
• wrist flexion (flexor carpi ulnaris)
• thumb adduction (adductor policis)

Question 11

What is the most common cause of medial nerve palsy?

Answer 11

Entrapment within the carpal tunnel at the wrist

- can be caused by inflammation and swelling of tendons within the tunnel

Question 12

What is the function of the median nerve?

Answer 12

Sensory
- the most lateral 3.5 fingers on the palm
Motor
- flexors of the forearm
- LOAF (lumbricals, opponens pollicis, abductor pollicis brevis and flexor pollicis brevis)

Question 13

What are the presenting symptoms of median nerve palsy?

Answer 13

Intermittent nocturnal pain
Numbness and tingling
Weak grip
Tinel’s sign
- lightly tapping the nerve to elicit tendernss and tingling over the wrist
Phalens test
- complete flexion of the wrist to elicit tingling and pain over the wrist

Question 14

Which muscles display weakness in median nerve palsy?

Answer 14

Lumbicals (1 and 2)
- flexion at the MCP joint
Opponens pollicis
- thumb opposition
Abductor pollicis brevis 
- thumb abduction
Flexor pollicis brevis
- thumb flexion

Question 15

What is the most common cause of anterior interosseous branch nerve palsy?

Answer 15

Trauma to the forearm

Question 16

What is the function of the anterior interosseous branch?

Answer 16

This nerve branches off the median nerve in the forearm where it travels deeper to supply

• pronator quadratus (hand pronation)
• flexor pollicis longus (allows OK sign)
• lateral part of flexor digitorum profundus (thumb flexion)

Question 17

What are the presenting symptoms of anterior interosseous nerve palsy?

Answer 17

History of forarm pain
Weak grip on keys
Tinels sign
Phalens test

Question 18

Which muscles are weakened by an anterior interosseous nerve palsy?

Answer 18

Pronator quadratus - flexion at MCP joint is limited
Flexor pollicus longus - thumb flexion
Flexor digitorum profundus - thumb flexion

Question 19

Give a brief description of the function of the nerve of the upper limb.

Answer 19

Radial nerve
- tennis backhand
- wrist and finger extension
Median nerve
- forearm flexors
- LOAF
Ulnar nerve
- intrinsic muscles of the hand

Question 20

Where is the lumbar plexus located?

Answer 20

Near iliopsoas

- damage to this muscles risks damage to the plexus

Question 21

Name the large nerves of the hip (supply the thigh).

Answer 21

Femoral nerve
Sciatic nerve
Obturator nerve

Question 22

Summarise the nerves of the thigh, and what they supply.

Answer 22

Femoral nerve 
- found in the front of the leg
- supplies the quads (knee extension and hip flexion)
Obturator nerve 
- found medially 
- hip adduction 
Sciatic nerve
- found in the back of the leg
- supplies the hamstrings (knee flexion, allowing running)

Question 23

What is the most common cause of femoral nerve palsy?

Answer 23

Haemorrhage or trauma

Question 24

What is the function of the femoral nerve?

Answer 24

Motor
- knee extension
- hip flexion
Sensory
- skin over the front and inner thigh, shin and arch of foot

Question 25

What are the presenting symptoms of femoral nerve palsy?

Answer 25

Weakened quadriceps Weakened hip flexion Numbness on medial shin

Question 26

Which muscles and actions are weakened in femoral nerve palsy?

Answer 26

Quadriceps - knee extension Iliopsoas - hip flexion Adductor magnus - hip adduction

Question 27

Once it has entered the lower leg, what happens to the sciatic nerve?

Answer 27

At the knee, it splits into - common pernoeal nerve (muscles in anterior and lateral leg compartments) - tibial nerve (posterior leg compartment and sole of the foot)

Question 28

Describe the pattern of distribution of the common pernoeal and tibial nerves?

Answer 28

Tibial - back of the leg - motor: gastrocnemius and soleus muscles of the calf Common peroneal - front of the leg - motor: tibialis anterior and the peroneus muscles - sensory: shin and dorsum of the foot

Question 29

What is the most common cause of common perneal nerve palsy?

Answer 29

Entrapment at the fibular head.

Question 30

What are the presenting symptoms of a common peroneal nerve palsy?

Answer 30

``` History of trauma, surgery or external compression Acute onset foot drop (plantarflexion) - stepage gait Sensory disturbance Painless ```

Question 31

How can you tell the difference between common peroneal nerve palsy and L5 radiculopathy?

Answer 31

L5 radiculopathy and common peroneal nerve palsy both have sensory change down the lateral skin and foot dorsum However L5 radiculopathy also has foot inversion

Question 32

Which muscles and movements would be weakened in common peroneal nerve palsy?

Answer 32

Tibialis anterior - ankle dorsiflexion | Extensor hallucis longus - great toe extension

Question 33

What is mononeuritis multiplex?

Answer 33

Simultaneous or sequential development of palsies of two or more nerves.

Question 34

List some common causes of mononeuritis multiplex.

Answer 34

``` Diabetes Vascilitic - Churg Strauss Rheumatological - RA, lupus, Sjogrens syndrome Infective - Hep C, HIV Sarcoidosis Lymphoma ```