What is the Carpal Tunnel Syndrome?
- Carpal Tunnel Syndrome is the most common upper extremity compression neuropathy that results from median nerve compression within the carpal tunnel.
- It was first described by Paget in 1854.
- It occurs most often in patients 30 to 60 years old, and is more common in women than in men
Anatomy of the carpal tunnel:
- The carpal tunnel is bound by the carpal bones arching dorsally.
- The hook of the hamate and the pisiform medially; and the scaphoid tubercle and trapezial ridge laterally.
- The palmar aspect, or “roof,” of the carpal tunnel is formed by the
flexor retinaculum, consisting of:
- The deep forearm fascia proximally
- The transverse carpal ligament over the wrist.
- The aponeurosis between the thenar and hypothenar muscles
- The most palmar structure in the carpal tunnel is the median nerve.
- Lying dorsal (deep) to the median nerve in the carpal tunnel are the nine flexor tendons of the finger and the flexor policies longus tendon FPL.
See Also: Tarsal Tunnel Syndrome
Risk factors for Carpal Tunnel Syndrome include:
- Female sex
- Cigarette smoking
- Vibrations associated with job tasks.
- Physically inactive individuals
Carpal Tunnel Syndrome Causes:
|Decrease in Size of Carpal Tunnel||■ Bony abnormalities of the carpal bones|
■ Flexion or extension of wrist
|Increase in Contents of Canal||■ Forearm and wrist fractures (Colles fracture, scaphoid fracture)|
■ Dislocations and subluxations (scaphoid rotary subluxation, lunate volar dislocation)
■ Posttraumatic arthritis (osteophytes)
■ Musculotendinous variants
■ Aberrant muscles (lumbrical, palmaris longus, palmaris profundus)
■ Local tumors (neuroma, lipoma, multiple myeloma, ganglion cysts)
■ Persistent medial artery (thrombosed or patent)
■ Hypertrophic synovium
■ Hematoma (hemophilia, anticoagulation therapy, trauma)
|Neuropathic Conditions||■ Diabetes mellitus|
■ Double-crush syndrome
■ Exposure to industrial solvents
|Inflammatory Conditions||■ Rheumatoid arthritis|
■ Nonspecific tenosynovitis
|Alterations of Fluid Balance||■ Pregnancy|
■ Thyroid disorders (especially hypothyroidism)
■ Renal failure
■ Long-term hemodialysis
■ Raynaud disease
■ Lupus erythematosus
■ Paget disease
|External Forces||■ Vibration|
■ Direct pressure
Symptoms of Carpal Tunnel Syndrome:
- Tingling and numbness in the typical median nerve distribution (thumb, index, long, and radial side of ring).
- Pain: aching, or throbbing, occurs diffusely in the hand and may radiate up the forearm.
- Thenar muscle atrophy usually is seen in late-stage nerve compression.
- Tinel sign
- Phalen test
- Durkan test
- Application of a blood pressure cuff on the upper arm sufficient to produce venous distention may initiate the symptoms (not recommended because of its insensitivity and nonspecificity).
See Also: Wrist and Hand Special Tests
- Electrodiagnostic studies including Nerve Conduction Velocities (NCV) and Electromyography (EMG) are reliable confirmatory tests.
Carpal Tunnel Syndrome in Children:
- Carpal tunnel syndrome in children is unusual.
- Predisposing factors may include:
- Lysosomal storage diseases
- A strong family history of carpal tunnel syndrome
- Symptoms in children may be confusing and include decreased dexterity and diffuse pain.
- Findings such as thenar muscle atrophy and weakness suggest that the condition is severe by the time of presentation.
- The Phalen test and Tinel sign may be absent if the nerve compression has been present for a long time.
Carpal Tunnel Syndrome Treatment:
Nonoperative Treatment of Carpal Tunnel Syndrome is indicated as a first line of treatment and for mild cases.
- NSAIDS, night splints, activity modifications.
- Steroid injections:
- Second line of treatment.
- Care should be taken not to inject directly into the nerve.
- It maybe used as diagnostic study.
- Kaplan, Glickel, and Eaton identify 5 risk factors to fail of nonoperative treatment: 1
- Age older than 50 years.
- Duration of the disease is longer than 10 months.
- Constant paresthesia.
- Stenosing flexor tenosynovitis.
- A positive Phalen test result in less than 30 seconds.
- When none of these factors was present, two-thirds of patients were cured by medical therapy.
Operative Treatment is indicated if nonoperative treatment is failed or in sever cases.
- Carpal Tunnel Release:
- If signs and symptoms are persistent and progressive, especially if they include thenar atrophy.
- When median nerve palsy develops after a radial fracture and has not improved after positional change.