Carpal Tunnel Syndrome

Carpal Tunnel Syndrome (CTS)

Overview

Compression of the Median nerve by transverse carpal ligament (Flexor retinaculum).

The most common entrapment neuropathy in the upper extremity.

Affect women more than men.

Usually bilateral, dominant hand tends to be more severely affected.

Most cases are idiopathic.

Epidemiological studies linked CTS to the following Job Tasks

	Meat & poultry processors
	Electronics Assemblers
	Garment Workers
	Aircraft Builders
	Frozen food processor

Keyboard use as cause of CTS is not confirmed by study.

Highly repetitive wrist & finger use is a greater risk factor than forceful hand use.

May be caused by other diseases

Endocrine

	Hypothyroidism
	Acromegaly
	Diabetes

Connective tissue disease: Rheumatoid Arthritis

Tumors: Ganglion, Lipoma, Schwannoma, Neurofibroma, Hemangioma

Congenital

	Persistent median artery
	Congenital small carpal tunnel
	Anomalous muscles (palmaris longus, flexor digitorum sublimis)

Infectious/Inflammatory:

	Sarcoid
	Histoplasmosis
	Septic arthritis
	Lyme

Trauma

	Fractures (especially Colle's fracture)
	Hemorrhage (including anticoagulation)

Miscellaneous

	Spasticity (persistent wrist flexion)
	Renal disease, hemodialysis
	Amyloidosis (familial and acquired)
	Pregnancy
	Any other condition which increases edema or total body fluid

Anatomy of Median nerve - Diagram

At the Brachial plexus

From divisions of lateral and medial cords.

	Lateral cord contains sensory fibers to digits 1-3 and motor fibers to the proximal median forearm muscles.
	Medial cord contains sensory fibers to digit 4 and motor fibers to the distal muscles of the forearm and hand.

At the Arm: does not innervate any muscle.

At the antecubital fossa, the nerve is adjacent to the brachial artery. Then it passes between the two heads of the Pronator teres.

At Forearm

	It innervates: Pronator teres, Flexor carpi radialis, Flexor digitorum sublimis, and sometimes the Palmaris longus.
	It branches out to Anterior Interosseous Nerve, a pure motor nerve, innervates the Pronator quadratus, Flexor pollicis longus, and medial head of the Flexor digitorum profundus (to digits 2 and 3).

At Wrist: palmar cutaneous branch arises, travels subcutaneously to supply sensation over the thenar eminence, and does not go through the tunnel.

At Carpal Tunnel:

	3 sides: carpal bones.
	Roof: transverse carpal ligament.
	The median nerve and nine flexor tendons pass through the tunnel.

In the hand:

	Muscular branches innervate the Opponens pollicis, Abductor pollicis brevis, superficial head of the Flexor pollicis brevis, and the First and second lumbricals.
	Sensory fibers supply the medial thumb, second and third digits, and lateral half of the fourth digit.

More anatomic pictures:

Electronic textbook of Hand Surgery

Symptoms

	Diffuse, poorly localized ache involving the entire hand and forearm. Many patients will describe the entire hand falling asleep, but if asked directly if the little finger is involved, will subsequently note that the little finger is spared.
	Symptoms are more common when a flexed or extended wrist posture is assumed.
	May be provoked by driving, holding the phone, a book or newspaper.
	Nocturnal paresthesias, waking patient up from sleep.

Signs

Two point discrimination may be affected before pain and temperature.

Even in severe cases, sensation over the thenar area in spared, as it is innervated by the palmar cutaneous sensory branch which arises proximal to and does not pass through the carpal tunnel.

The three provocative tests: Tinel's sign, Phalen's maneuver and the direct compression test are sometimes useful.

Motor examination - Hand muscle anatomy

Look for muscle atrophy

Testing strength of thumb abduction and opposition.

Difficult to isolate the muscle action of

	Abductor pollicis brevis: Thumb abduction may also be performed by the abductor pollicis longus (radial nerve)
	Opponens pollicis: thumb opposition may also be produced by a combination of the flexor pollicis brevis (deep head - ulnar nerve) and the flexor pollicis longus (anterior interosseous nerve.

Test positive in	CTS pt	control
Tinel's sign: paresthesias provoked by tapping over the median nerve at the wrist	26-73%	6-45%
Phalen's test: holding the wrist flexed produces paresthesias within 1-2 minutes	74%	25%

Differential diagnosis of CTS from other disorder - NL

Electrodiagnosis

Distal motor latency

	Stimulate the median nerve at the wrist and recording the abductor pollicis brevis muscle.
	Latency > 3.7 ms considered abnormal.
	Over 50% of CTS: distal median motor latency is within the normal limit.

Distal sensory latency

	Orthodromic or antidromic sensory studies by stimulating or recording the index or middle fingers.
	Stimulating or recording at the palm 8cm from the wrist.

Use of internal control to increase sensitivity

	Compare median and ulnar: from palm to wrist at a distance of 8 cm, significant if difference > 0.4 ms.
	Compare median and radial nerves: stimulate thumb & record at wrist at a distance of 10 cm, significant if difference > 0.5 ms.

Classification: see table below

Noninvasive Treatment

Wrist splint: Lightweight neutral position plastic/Velcro splints that allow semi free finger movement. Watch for "frozen wrist".

Modify activity: reduce wrist flexion, extension, rotation, finger flexion & forceful griping

NSAID: watch for the usual side effects

Diuretic in patients with limb swelling

Report of short term low dose steroid: 20 mg qd x 2 weeks, then 10 mg qd x 2 weeks produce better symptomatic relief.

Local steroid injection:

	Short term: about 80% improvement.
	Technique: Using an 1 in (2.5 to 3.9 cm) 25-ga needle directed at an angle of 60� to the skin surface, pointing toward the palm just medial or ulnar to the palmaris longus tendon, and proximal to the distal crease at the wrist.
	The needle is advanced 1 to 2 cm, and 20 to 40 mg of prednisolone suspension with or without Lidocaine are injected along the track and into the tissue space.
	Up to 2 weeks may be needed to see improvement.
	Do not inject more than 2 to 3 times, as tendon injury may occur.
	More information on injection

Study showed: 22% free of symptom after one year when treated by splinting, local steroid injection.

Surgical treatment

75-90% satisfactory results

Cause of incomplete relief

	delayed nerve recovery
	incomplete section of flexor retinaculum
	multicausal hand symptoms
	incorrect preop diagnosis

Recurrent symptom after initial success

	perineural fibrosis
	progressive tenosynovitis
	refibrosis of flexor retinaculum

New symptom patterns after surgery: joint stiffness, nerve branch injury, reflex sympathetic dystrophy, infection etc

Endoscopic release: classified as experimental, increased risk of injury to digital branches of Median nerve

References & Further Readings

	Electronic textbook of Hand Surgery
	Review - Wheeless Textbook of Ortho
	Review - Univ of S Florida
	Review w management algorithm - Vermont program for Quality in Health Care
	CTS - is it work related? - Hosp Practice
	Chang, MH et al. Oral drug of choice in Carpal tunnel Syndrome. Neurology. 51(2)390-3. Aug 1998
	Dawson, DM, Hallett M, Wilbourn AJ. Entrapment Neuropathies. 3rd Edition. Pg. 20-94. Lippincott-Raven.
	Campbell W.W. Diagnosis And Management Of Common Compression And Entrapment Neuropathies. Neurologic Clinics. 15(3)549-567. Aug 1997.
	Nuber, GW et al. Neurovascular Problems in the Forearm, wrist and Hand. Clinics in Sports Medicine. 17(3). July 1998.
	Verdon ME. Prim Care Overuse Syndrome of the hand and wrist. 23(2): 305-19. June 1996.

Patient Information

Review - Univer of Washington

Patient's guide from Sechrest

	CTS
	DeQuervain's Tenosynovitis