Carpal Tunnel Syndrome: Features and Treatment

Anatomy of Carpal Tunnel:

Carpal tunnel is a narrow passageway in the wrist formed by:

Posterior side: 8 carpal bones

Anterior side: Transverse carpal ligament

Contents:

9 Flexor tendons

Median Nerve

Median Nerve Distribution in Hand:

Origin: From lateral and medial cords of brachial plexus

Motor innervation:

Lumbricals: 1st and 2nd

Muscles of thenar eminence: Opponens pollicis, Abductor Pollicis Brevis and Flexor Pollicis Brevis)

Mnemonic: LOAF (Lumbricals, Opponens pollicis, Abductor Pollicis Brevis and Flexor Pollicis Brevis)

Sensory innervation:

Skin of the palmar side of the thumb, the index and middle finger, half the ring finger, and the nail bed of these fingers (3 and 1/2 digits)

Lateral part of the palm by palmar cutaneous nerve (unaffected in Carpal tunnel syndrome)

Carpal Tunnel Syndrome

It is a syndrome characterized by the compression of the median nerve as it passes beneath the flexor retinaculum in carpal tunnel.

Causes:

Any space occupying lesion (SOL) of carpal tunnel can cause carpal tunnel syndrome –

Inflammatory causes:

• Rheumatoid arthritis
• Wrist osteoarthritis

Post-traumatic causes:

• Colle’s fracture

Endocrine causes:

• Myxoedema
• Acromegaly

Idiopathic

Mnemonic: MEDIAN TRAP

• Myxoedema
• Edema premenstrually
• Diabetes
• Idiopathic
• Acromegaly
• Neoplasm
• Trauma
• Rheumatoid arthritis
• Amyloidosis
• Pregnancy

Clinical features:

It usually occurs in females between the age of 40 and 70. They complain of tingling, numbness or discomfort in the lateral 3 and 1/2 fingers i.e. distribution of median nerve. They also complain of intermittent attacks of pain in the distribution of the median nerve on one or both sides. The attacks frequently occur at night. The reason symptoms are worse at night may be related to the flexed-wrist sleeping position and/or fluid accumulating around the wrist and hand while lying flat. Pain may be referred proximally to the forearm and arm.

Motor changes: Ape-like thumb deformity, loss of opposition of thumb, index and middle fingers lag behind when making the fist

Sensory changes: Loss of sensations on lateral 3 and 1/2 digits including the nail beds and distal phalanges on dorsum of hand

Vasomotor changes: The skin areas with sensory loss is warmer due to arteriolar dilation; it is also drier due to absence of sweating due to loss of sympathetic supply

Tropic changes: Long-standing cases of paralysis lead to dry and scaly skin. The nails crack easily with atrophy of the pulp of fingers.

Tests

To approximate where along the wrist the median nerve runs, gently flex and radially (laterally) deviate your wrist. Two tendons will become palpable and even visible—palmaris longus (in midline) and flexor carpi radialis

(lateral to it). However, 15% of people do not have a palmaris longus muscle. The median nerve runs deep between these tendons.

Phalen’s Test:

Bend the patient’s wrists downwards as shown in the figure

This position should be held for about 1 minute.

Positive test : numbness or tingling along the median nerve distribution

Tinel’s Test:

With the palm up, tap over the carpal tunnel area of the wrist 5 or 6 times

Positive test : tingling or paresthesia in the median nerve distribution

Durkan Test:

Press thumb over carpal tunnel and hold pressure for 30 seconds.

Positive test: Onset of pain or paresthesia in the median nerve distribution

Electromyogram (EMG)

Nerve conuction studies are done for diagnosis these days

Treatment

1. Immobilizing braces/Splints
2. Analgesics like NSAIDs
3. Local injection of steroids
4. Surgery: Dividing the flexor retinaculum

Carpal Tunnel Syndrome as Occupational Disease

Causes:

1. repetitive hand motions
2. awkward hand positions
3. strong gripping
4. mechanical stress on the palm
5. vibration

Common occupations:

1. Cashiers
2. Hairdressers
3. Knitters
4. Farmers (milking cow)
5. Office workers (keyboarding)
6. Painter, etc.