[11] Carpal Tunnel Syndrome Flashcards
What is carpal tunnel syndrome?
A collection of symptoms and signs caused by compression of the median nerve in the carpal tunnel
What is the carpal tunnel?
An anatomical compartment at the base of the palm
What forms the postero-lateral boundary of the carpal tunnel?
Scaphoid and trapezium
What forms the postero-medial boundary of the carpal tunnel?
Hook of the hamate and the pisiform
What forms the anterior boundary of the carpal tunnel?
The flexor retinaculum
What is the contents of the carpal tunnel?
- 9 flexor tendons in synovial sheaths
- Median nerve
What are the 9 flexor tendons in the carpal tunnel?
- 4 of flexor digitorum profundus
- 4 of flexor digitorum superficialis
- Flexor pollicis longus
What happens to the median nerve before entering the carpal tunnel?
It gives of the palmar cutaneous branch
What is the role of the palmar cutaneous branch of the median nerve?
It provides sensation to the lateral palm of the hand
What is true of the palmar cutaneous branch in carpal tunnel syndrome?
It does not travel through the carpal tunnel and so there is often sparing of the lateral palm in carpal tunnel syndrome
Once it has passed through the carpal tunnel what branches are given off by the median nerve?
- Recurrent motor branch
- Palmar digital nerves
What is the role of the recurrent motor branch of the median nerve?
Supplies the thenar muscle group
What is the role of the palmar digital nerve of the median nerve?
- Sensory innervation to the palmar skin and dorsal nail beds of the lateral 3and 1/2 digits
- Motor innervation of the lateral 2 lumbricals
What can lead to compression of the median nerve within the carpal tunnel?
- Decrease in size of the tunnel
- Increase in size of the contents
- Both
Why does increased tunnel pressure lead to compression of the median nerve?
The boundaries of the carpal tunnel are rigid
What are the risk factors for carpal tunnel syndrome?
- Obesity
- Repetitive wrist work
- Pregnancy
- Genetics
- Rheumatoid arthritis
What repetitive wrist work can lead to increased risk of carpal tunnel syndrome?
- Computer work
- Work with vibrating tools
- Work that requires a strong grip
Wha tis carpal tunnel syndrome characterised by?
Tingling, numbness or pain in the distribution of the affected median nerve branches
What are the areas affected by carpal tunnel syndrome?
- Thumb
- Index and middles fingers
- Medial half of the ring finger on the palmar aspect
When is carpal tunnel syndrome pain often worse?
At night
How can symptoms of carpal tunnel syndrome develop?
They can become more persistent and radiate to the forearm, elbow, arm and shoulder
What clinical sign may be present in later carpal tunnel syndrome?
Wasting of the thenar muscles
How can carpal tunnel syndrome be clinically identified?
- Positive Phalen’s test
- Positive Tinel’s sign
- Positive carpal tunnel compression test
What is a positive Phalen’s test?
Flexing the wrist for 60 seconds causes pain or paraesthesia in the median nerve distribution
What is a positive Tinel’s sign?
Tapping lightly over the median nerve at the wrist causes distal paraesthesia in the median nerve distribution
What is a positive carpal tunnel compression test?
Pressure over the proximal edge of the carpal ligament (proximal wrist crease) causes paraesthesia to develop or increase in median nerve distribution
When are investigations for carpal tunnel syndrome needed?
When there is diagnostic doubt or before surgery
What investigations can be used for carpal tunnel syndrome?
Electroneurography (ENG)
What happens in ENG for carpal tunnel syndrome?
The median nerve is stimulated proximal to the carpal ligament and compound muscle action potential is picked up over the thenar eminence
What are the differentials for carpal tunnel syndrome?
- Other median nerve compression
- Cervical radiculopathy
- Thoracic outlet syndrome
- Tendonitis
- Ulner neuropathy
- MS
Over what period may carpal tunnel syndrome spontaneously resolve?
6 months
When is spontaneous resolution of carpal tunnel syndrome most likely?
- Under 30’s
- Unilateral
- Short duration
- In women who were precipitated by pregnancy
What conservative management can be used for carpal tunnel syndrome?
- Minimise exacerbating activities
- Splinting
When should referral be made for patients with carpal tunnel syndrome?
- Diagnosis is uncertain
- Treatments have failed after 3 months
- Severe, persisting symptoms, especially if thumb weakness
What may treatment for carpal tunnel syndrome involve?
- Local corticosteroid injections
- Surgical treatment
- Physiotherapy
What does surgical treatment for carpal tunnel syndrome involve?
Release of the nerve by cutting the transverse carpal ligament
What are the disadvantages of surgical treatment of carpal tunnel syndrome?
- Surgery related pain
- Hand weakness
- Complications of surgery
What physiotherapy techniques can be used in carpal tunnel syndrome?
- Stretching of the wrist to improve blood flow
- Exercises to improve strength and flexibility
