Carpal tunnel syndrome

Question 1

Define carpal tunnel syndrome.

Answer 1

Carpal tunnel syndrome (CTS) refers to the symptom complex brought on by compression of the median nerve in the carpal tunnel.

Question 2

What is the aetiology of carpal tunnel syndrome?

Answer 2

Compression of the median nerve within the carpal tunnel (formed by the
flexor retinaculum superiorly and the carpal bones inferiorly).

Usually idiopathic (43%) but may be secondary to….

Question 3

What might carpal tunnel syndrome be secondary to?

Answer 3

• Tenosynovitis: Overuse, rheumatoid arthritis, other inflammatory rheumatic disease.
• Infiltrative diseases of the canal/increased soft tissue:
• Amyloidosis, myeloma myxoedema, acromegaly.
• Bone involvement in the wrist: Osteoarthritis, fracture, tumour.
• Fluid retention states: Pregnancy, nephrotic syndrome.
• Other: Obesity, menopause, diabetes, end-stage renal disease

Question 4

How common is carpal tunnel syndrome?

Answer 4

• Overall prevalence 2.7%.
• Incidence in adults
• 0.1% per year.
• Lifetime risk 10%.

Question 5

What are the symptoms of carpal tunnel syndrome?

Answer 5

• Tingling and pain in the hand and fingers
• Night time worsening - (patients may be woken up at night).
• Gradual onset and intermittent symptoms
• Numbess of hand
• Weakness and clumsiness of hand and thenar muscles

Question 6

What are the signs of carpal tunnel on examination?

Answer 6

• Sensory impairment in median nerve distribution (first 31/2 fingers).
• Weakness and wasting of the thenar eminence (abductor pollicis brevis and opponens)
• Tinel’s sign: Tapping carpal tunnel triggers symptoms.
• Phalen’s test: Maximal flexion of the wrist for 1 min may cause symptoms. Signs of the underlying cause, e.g. hypothyroidism or acromegaly.
• Normal reflexes, numbness confined to palmar aspect of first 4 fingers.

Question 7

What investigations would you do for carpal tunnel syndrome?

Answer 7

Blood: TFTs, ESR.

US of wrist - space occupying lesion may be identified

EMG/Nerve conduction study: Shows impaired median nerve conduction across the carpal tunnel in the context of normal conduction elsewhere. May show demyelination/scarring of nerve.

Question 8

What are the risk factors for carpal tunnel syndrome?

Answer 8

• >30 years
• high BMI
• female
• alteration in carpal tunnel space
• fractured wrist/carpal bones
• square wrist - ratio of wrist depth to wrist width is greater than 0.7 (women have higher ratios)
• rheumatoid arthritis
• diabetes - polyneuropathy
• dialysis - deposition of amyloid on tendons?
• pregnancy
• congenital carpal tunnel stenosis
• occupation involving exposure to repetitive bending, twisting or vibration of the hands or wrist
• mobility aids

Other: amoking, white, thyroid, hormones, computer use, physcial inactivity, sports and activities.