Peripheral Nerve Palsy

Question 1

What examination can be done to test for Carpal Tunnel Syndrome?

Answer 1

Tinel’s Test- Tap over carpal tunnel

Phalen’s Test- Flex the wrist for 60 seconds

Question 2

What are symptoms of carpal tunnel syndrome?

Answer 2

Pain and tingling in the thumb, index finger, middle finger and lateral side of the ring finger on the palmar side

Question 3

Describe the sensory innervation of the hand

Answer 3

Median nerve- palmar side of thumb, index finger, middle finger and lateral ring finger
Ulnar nerve- palmar side of medial ring finger and little ring and same on back of the hand
Radial Nerve- Dorsal surface of the thumb, index finger, middle finger and lateral half of ring finger

Question 4

What is seen on examination of patients with carpal tunnel syndrome?

Answer 4

Wasting of the thenar muscles
Sensory reduction on palmar surface of thumb, index finger, middle finger and lateral third of ring finger
Weakness of abductor pollicis brevis

Note- nerve branch from median nerve supplies the palm and this does not pass through the tunnel so sensation is not altered there

Question 5

What are the boundaries of the carpal tunnel?

Answer 5

Roof- Flexor Retinaculum

Floor- Carpal bones

Question 6

What are the carpal bones?

Answer 6

Some Lovers Try Positions That They Cant Handle

Scaphoid
Lunate
Triquetrum
Pisiform
Trapezoid
Trapezium
Capitate
Hamate

Question 7

What causes carpal tunnel syndrome?

Answer 7

Compression of the median nerve- may be due to:
Idiopathic
Inflammation
XS GH- Acromegaly
Hypothyroidism
Diabetes
Rheumatoid arthritis (joint inflammation)
Osteoarthritis 
Pregnancy- often settles after delivery

Question 8

How is carpal tunnel syndrome investigated?

Answer 8

Nerve conduction studies- reduced conduction rate.

Question 9

What is the management for carpal tunnel syndrome?

Answer 9

Reduce typing
Wrist splints
Local steroid injections
Decompression surgery- incision in flexor retinaculum

Question 10

How does ulnar nerve irritation commonly present?

Answer 10

Paresthesia/ reduced sensation/ pain in the little finger and medial side of ring finger on palmar side

Question 11

What does the median nerve innervate?

Answer 11

Flexor and pronator muscles in the anterior compartment of the forearm (except for flexor carpi ulnaris which is innervated by the ulnar nerve)
Thenar muscles
Lateral two lumbricals

Question 12

What are the nerve roots of the median nerve?

Answer 12

C6 to T1

Question 13

What are the motor innervations of the ulnar nerve?

Answer 13

All the intrinsic muscles of the hand (except for the lateral two lumbricals and thenar muscles- median nerve)
Flexor carpi ulnaris
Medial half of flexor digitorum profundus (flexes ring and little finger at DIP)

Question 14

What might be seen for an ulnar nerve lesion?

Answer 14

Reduced sensation over palmar/dorsal surface of the little and medial side of ring ringer
Wasting of muscles of hand with thenar sparing
Ulnar claw- due to weakness of the intrinsic muscles of the hand which flex the MCP and extend the IPs- does causes long flexors and extensors to take over (in the forearm). Note if at the elbow there is loss of supply to the medial half of flexor digitorum profundus causing extension of the DIP of ring and little ringer.

Question 15

What causes damage to the ulnar nerve?

Answer 15

Lacerations at the wrist
Fractures at the elbow
Compression at the elbow
Dislocation at the elbow
Osteoarthritic changes at elbow

Question 16

What investigation should be done for ulnar nerve palsy?

Answer 16

Nerve conduction studies

Question 17

What clinical sign can test for ulnar nerve palsy?

Answer 17

Froment’s sign- paralysis of adductor pollicis- can’t hold paper between thumb and index finger

Question 18

What muscles are innervated by the median nerve?

Answer 18

Lateral two lumbricals
Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis

(LOAF)

Question 19

What does muscles does the radial nerve innervate?

Answer 19

Triceps

Extensor muscles in the forearm

Question 20

What does a lesion of the radial nerve cause?

Answer 20

Wrist drop

Inability to extend the fingers at the MCP due to weakness of extensors in the forearm

Question 21

Where does the radial nerve provide sensory innervation to?

Answer 21

Posterior of the forearm
Dorsal surface of thumb, index finger, middle ringer and lateral half of ring finger

Lots of overlap so check the web space between thumb and index finger)

Question 22

What muscles does the radial nerve innervate?

Answer 22

Triceps
Brachioradialis
Extmespr carpi radialis longus

Question 23

What can cause radial nerve injury?

Answer 23

Fracture of the humeral shaft- radial nerve passes in the radial groove
Shoulder dislocations (also causes weakness of the triceps)
Crutch trauma at the level of the axilla

Question 24

What does a common peroneal nerve palsy cause?

Answer 24

Foot drop- if permanent causes a high stepping gait.

Also weakness in eversion

Question 25

Where does injury to the common peroneal nerve often happen?

Answer 25

At the level of the fibula via compression or fracture

Also causes weakness of ankle eversion which should be tested. Also weakness of big toe extension

Question 26

What are some other causes of foot drop?

Answer 26

L5 nerve root lesion

Sciatic nerve lesion

Question 27

What is done to diagnose any peripheral nerve lesion?

Answer 27

Nerve conduction studies

Question 28

What is mononeuritis multiplex?

Answer 28

Multiple nerves are involved in an asymmetrical distribution

Question 29

How can you differentiate between a common peroneal nerve injury and an L5 nerve root lesion?

Answer 29

L5- there will be weakness of ankle inversion too

Also likely to describe back pain