Peripheral Neuropathies

Question 1

What is carpal tunnel syndrome

Answer 1

Compression of the median nerve passing through the carpal tunnel in the wrist

Question 2

What are the nerve roots of the median nerve

Answer 2

C6-T1

Question 3

What are the two primary causes of compression in Carpal Tunnel Syndrome?

Answer 3

• Swelling of the contents (e.g., tendon sheaths due to repetitive strain).
• Narrowing of the carpal tunnel.

Question 4

Which branches of the median nerve responsible for sensory innervation of the hand are affected in carpal tunnel syndrome

Answer 4

• recurrent branch
• palmar digital nerves

Question 5

What are some key risk factors associated with Carpal Tunnel Syndrome? (5)

Answer 5

• Age 40-60
• Female
• High BMI
• Pregnancy
• Diabetes, hypothyroid, acromegaly

Question 6

Give 3 causes of carpal tunnel syndrome

Answer 6

• rheumatoid arthritis
• oedema
• pregnancy

Question 7

How does Carpal Tunnel Syndrome typically present in terms of symptom onset and characteristics?

Answer 7

• Onset: gradual, initially intermittent and often worse at night
• numbness, paraesthesia, pain in thumb, index and middle finger

Question 8

Describe signs that would indicate carpal tunnel syndrome on examination

Answer 8

• weakness of thumb abduction (abductor pollicis brevis) - difficulty opening jars
• wasting of thenar eminence (NOT hypothenar)
• Tinel’s sign: tapping causes paraesthesia
• Phalen’s sign: flexion of wrist causes symptoms

Question 9

Which part of the hand is typically spared in Carpal Tunnel Syndrome, and why?

Answer 9

The palm is usually spared because the palmar cutaneous branch, responsible for its innervation, does not travel through the carpal tunnel.

Question 10

What is considered the diagnostic test of choice for Carpal Tunnel Syndrome and what would be a positive finding?

Answer 10

Electromyography (EMG).
* motor + sensory: prolongation of the action potential

Question 11

What are the management options for Carpal Tunnel Syndrome?

Answer 11

6-week trial of conservative treatments if the symptoms are mild-moderate:
* wrist splints (particularly useful in pregnancy) +/- steroid injections
Severe/ persistent symptoms:
* surgical decompression

Question 12

What structure is divided in the surgical management of carpal tunnel syndrome

Answer 12

The flexor retinaculum, aka the transverse carpal ligament

Question 13

What is the most common mononeuropathy

Answer 13

Carpal tunnel syndrome

Question 14

What are the nerve roots of the radial nerve

Answer 14

C5-T1

Question 15

What group of muscles does the radial nerve mainly innervate in the hand

Answer 15

motor: Extensor muscles of the hand
sensory: dorsal aspect of the hand (this does not apply to the little finger and part of the ring finger)

Question 16

How does a radial nerve palsy present

Answer 16

Wrist drop

Question 17

What are the nerve root of the ulnar nerve

Answer 17

C8, T1

Question 18

What does the ulnar nerve supply sensory innervation to

Answer 18

medial 1 1/2 fingers (palmar and dorsal aspects)

Question 19

How would damage of the ulnar nerve at the wrist present

Answer 19

• ‘claw hand’ - hyperextension of the MCPJ and flexion at the distal and proximal IPJ of the 4th and 5th digits
• wasting and paralysis of hypothenar muscles
• wasting and paralysis of intrinsic hand muscles (except lateral two lumbricals)

Question 20

What are the two most common causes of foot drop

Answer 20

• common peroneal nerve lesion
• L5 radiculopathy

Question 21

What is peripheral neuropathy

Answer 21

Reduced sensory and/or motor function in peripheral nerves

Question 22

Give 5 causes of peripheral neuropathy

Answer 22

Alcohol
B12 deficiency
Cancer and CKD
Diabetes and Drugs
Vasculitis

Question 23

Name 4 drugs that can cause peripheral neuropathy

Answer 23

• Amiodarone
• vincristine
• nitrofurantoin
• metronidazole

Question 24

What is the typical presentation of peripheral neuropathy

Answer 24

• Numbness and tingling in hands/feet
• Muscle weakness
• Loss of balance

Question 25

Describe the characteristic distrubution of polyneuropathy pathology

Answer 25

Usually symmetrical and starts distally - glove and stocking distribution

Question 26

Give 3 pathological mechanisms resulting in peripheral neuropathy

Answer 26

• Demyelination
• Axonal degeneration
• Nerve compression

Question 27

Give 4 peripheral neuropathies that predominately cause a motor loss

Answer 27

• Guillain Barre - motor
• Charcot Marie Tooth
• lead poising
• diphtheria

Question 28

Give 4 peripheral neuropathies that predominately cause a sensory loss

Answer 28

• diabetes
• alcoholism (sensory-> motor)
• Vit B12 deficiency
• Uraemia

Question 29

How are polyneuropathies managed

Answer 29

• Treat the underlying cause
• Physio
• Podiatrist
• Analgesia for neuropathic pain (e.g. amitriptyline, pregabalin)

Question 30

What is mononeuritis multiplex

Answer 30

group of disorder that involve damage to at least two separate peripheral nerves

Question 31

What commonly causes mononeuritis multiplex

Answer 31

vasculitis
* Microscopic polyangiitis
* Polyarteritis nodosa
* Eosinophilic granulomatosis with polyangiitis

Question 32

What is the typical distribution of sensory loss in diabetic neuropathy?

Answer 32

‘Glove and stocking’ distribution, with the lower legs affected first.

Question 33

What is the first-line treatment for diabetic neuropathy?

Answer 33

Amitriptyline, duloxetine, gabapentin, or pregabalin
- if one doesn’t work, try another

Question 34

What is used as ‘rescue therapy’ for exacerbations of neuropathic pain in diabetic neuropathy

Answer 34

tramadol

Question 35

What topical treatment can be used for localized neuropathic pain in diabetic neuropathy (e.g., post-herpetic neuralgia)?

Answer 35

topical capsaicin

Question 36

How should resistant diabetic neuropathy be managed

Answer 36

pain management clinics