Clinical neurophysiology

Question 1

What are the different sections of the brachial plexus?

Answer 1

• roots
• trunks
• divisions
• cords
• nerves (median, ulnar and radial)

Question 2

What three nerves does the brachial plexus end in?

Answer 2

Musculocutaneous 
axillary 
radial 
median 
ulnar

Question 3

What does the median nerve supply?

Answer 3

thumb, index, middle and half ring finger

Question 4

What does the ulnar nerve supply?

Answer 4

pinky and half ring finger

Question 5

What does the radial nerve supply?

Answer 5

dorsal hand

Question 6

What motor fibres does the median nerve supply?

Answer 6

median muscle forearm (proximal and distal) and hand

Question 7

What nerve root fibres make up the median nerve?

Answer 7

C5 + C6 (lateral cord)

C8 + T1 (medial cord)

Question 8

What is the primary function of the lateral and medial cord of the median nerve?

Answer 8

lateral is mainly sensory

medial is mainly motor

Question 9

What nerve branches of the median nerve at the elbow?

Answer 9

anterior interosseous nerve

Question 10

What is the most common median nerve pathology?

Answer 10

Carpal tunnel syndrome (entrapment neuropathy)

Question 11

Who is entrapment of median nerve most common in?

Answer 11

females

45-65 yrs

Question 12

What would be the main differential diagnosis of carpal tunnel syndrome?

Answer 12

Lesion of:

• C6-7
• Brachial plexus
• Proximal median nerve lesion
• motor neurone disease (shouldnt have sensory disturbance)

Question 13

What are the symptoms of carpal tunnel syndrome?

Answer 13

• paraesthesia in median distribution (can present as whole hand)
• worse during sleep/ on wakening
• loss of dexterity
• can present in dominant hand first

Question 14

What are the risk factors for carpal tunnel?

Answer 14

• small carpal tunnel
• diabetes mellitus
• inflammatory conditions
• pregnancy, menopause and obesity
• hypothyroidism or renal disorder
• occupational (farmers)

Question 15

Where will sensation often be spared in carpal tunnel?

Answer 15

thenar eminence as supplied by palmar cutaneous sensory branch

Question 16

What are the tests for the hand?

Answer 16

Tinels (hand tapping)

Phalens (pushing dorsal aspect of hands against each other, hold at shoulder level for 60s)

Question 17

What would motor examination of carpal tunnel syndrome show?

Answer 17

wasting thenar eminence

weakness thumb abduction and opposition

Question 18

What muscles are supplied by the anterior interosseous nerve?

Answer 18

flexor digitorum profundus (flex distal phalanx or index and middle finger)
flexor pollicus longus (flexes distal phalanx thumb)
Pronator quadratus

Question 19

How would weakness of anterior interosseous nerve present?

Answer 19

• weakness of flexor pollicus longus
• no sensory symptoms
• normal abductor pollicus brevis
• can’t work lighter or take photo on camera

Question 20

Where is Ulnar nerve most commonly trapped?

Answer 20

elbow

Question 21

Which roots is ulnar nerve derived from?

Answer 21

C8-T1

Question 22

What are the branches of the ulnar nerve?

Answer 22

• dorsal cutaneous branch (dorsal part of hand on ulnar border)
• palmar cutanoues branch (palmar area on ulnar border)
• superficial terminal branches (pinky and half ring finger)

Question 23

What is the most common ulnar neuropathy?

Answer 23

compression
stretch
elbow injury

Question 24

What are the motor symptoms of ulnar neuropathy?

Answer 24

• decreased grip and pinch
• atrophy of hypothenar eminence and intrinsic hand muscles
• claw hand

Question 25

If Ulnar damage is at the wrist which branches will be spared?

Answer 25

- dorsal cutaneous and palmar cutaneous | - meaning only sensory disturbance at fingers not at rest of hand

Question 26

What will lesion at medial cord result in?

Answer 26

finger, hand and forearm

Question 27

What will ulnar lesion at elbow affect?

Answer 27

finger and hand (forearm not affected)

Question 28

What causes wrist drop?

Answer 28

``` CNS lesion C7/8 radiculopathy brachial plexopathy spiral groove PIN ```

Question 29

Why do you get wrist drop?

Answer 29

weakness of wrist muscles

Question 30

What does sensory involvement of wrist drop tell us?

Answer 30

lesion must be above where posterior interosseous nerve branches off (elbow)

Question 31

If there is no sensory involvement with wrist drop what is the cause?

Answer 31

damage to the posterior interosseous nerve

Question 32

What nerve does the posterior interosseous nerve branch from?

Answer 32

Radial