Carpal Tunnel

Question 1

what is the typical presentation of carpal tunnel syndrome?

Answer 1

Numbness, tingling, difficulty flexing/extending of thumb and radial fingers, wasting of thenar eminence - gradual (and often wake pt up @ night/ associated with activity during the day + relieved by shaking the wrist) - EMG (diagnostic)

Question 2

define carpal tunnel syndrome?

Answer 2

symptoms and signs brought on by compression of median nerve in the carpal tunnel

Question 3

what structures are in the carpal tunnel?

Answer 3

Flexor digitorum profundus (four tendons)

Flexor digitorum superficialis (four tendons)

Flexor pollicis longus

Median nerve

Question 4

state a mneumonic to remember the causes of carpal tunnel?

Answer 4

Question 5

outline the aetiology of carpal tunnel?

Answer 5

Symptoms are caused by compression of the median nerve as it runs through the carpal tunnel

Usually IDIOPATHIC

May be SECONDARY to:

• Tenosynovitis(e.g. in rheumatoid arthritis)
• Infiltrative diseases of the canal/increased soft tissue (e.g. amyloidosis, acromegaly)
• Bone involvement in the wrist (e.g. osteoarthritis, fracture)
• Fluid retention states (e.g.pregnancy, nephrotic syndrome)
• Other (e.g. obesity, menopause, diabetes)

Question 6

what are the risk factors for carpal tunnel?

Answer 6

variations of anatomy of the carpal tunnel

over 30 yrs

high BMI

Pregs

occupations involving repetitive movements of the wrist

fractured wrist/ carpal bones (lunate)

Rheumatoid arthritis

DM

Dialysis

Question 7

summarise the epidemiology of carpal tunnel?

Answer 7

Prevalence: 2.7%

Lifetime risk of 10%

Question 8

what are the presenting symptoms of carpal tunnel?

Answer 8

Symptoms are intermittent and gradual onset

Tingling and pain in the hand and fingers

Weakness and clumsiness of the hand (difficulty in fine motor tasks)

Waking up at night-time with paraesthesias/pain in hand/wrist, and shaking the hand to relieve symptoms – CLASSIC

Question 9

what are the signs of carpal tunnel on phyical examination?

Answer 9

Sensory impairment in the median nerve distribution

Weakness and wasting of thenar eminence

Tinel’s Sign - tapping the carpal tunnel causes symptoms

Phalen’s Test - flexion of the wrist for 1 min may cause symptoms

Look out for signs of the underlying cause (e.g. acromegaly, hypothyroidism)

NORM REFLEXES

Question 10

what are the appropriate investigations for carpal tunnel syndrome?

Answer 10

EMG – diagnostic test – focal slowing of conduction velocity (prolongation of AP) in the median sensory N across the carpal tunnel– useful in assessing severity of damage, helping with the choice of management, judging the success of interventions + determining prognosis

Bloods - looking for potential underlyign causes

• TFTs
• ESR