CARPAL TUNNEL SYNDROME
Definition
Carpal tunnel syndrome is the most common entrapment neuropathy of the upper extremity. The tunnel is formed dorsally by the volar surfaces of the carpal bones: its palmar surface is formed by the carpal ligament. The carpal tunnel is a rigid enclosure through which the median nerve and nine flexor tendons pass. Carpal tunnel syndrome occurs when, for a variety of reasons, the median nerve is compressed within or adjacent to the carpal canal. The prevalence rate is approximately 1 per 1,000 people a year. The pathophysiology of CTS typically is demyelination. In more severe cases, secondary axonal loss may be present. The most consistent findings of biopsy specimens of tenosynovium in patients undergoing surgery for idiopathic CTS have been vascular sclerosis and oedema.
Signs and Symptoms Sensory disturbance:
- Paresthesia: Tingling, pricking or burning, 80% of patients
- Sensory loss/numbness—usually with gradual onset
- Appears in thumb, index, and middle fingers, and often the radial half of the ring finger
- Symptoms intermittent, often aggravated by grasping from a flexed position or by repetitive rotary or repetitive flexion-extension movements, and worse at night
- Cold intolerance
- Phalen's sign
- Tinel's sign
- Carpal compression test
- "Volar hot dog" sign—swelling on ulnar side of palmaris longus tendon
- Weakness of median-nerve innervated hand muscles
Pain:
Volar wrist, sometimes extending into fingers and forearm
Worse at night, after strenuous activity. Hand weakness, clumsiness
Symptoms improve with hand shaking or motion restriction
May be bilateral
Aetiology / Risk Factors
- Thickening of the transverse carpal ligament or synovial sheath hypertrophy causes median nerve compression
- Idiopathic causes
- Repetitive motion, repetitive minor trauma, prolonged extreme posture, exposure to vibration
- Trauma to area, Colles' fracture
- Retention of fluid in the soft tissue of the wrist during pregnancy or menopause
- Space-occupying lesions—ganglion, calcification, hypertrophic fat, tumour (e.g., neurofibroma, neurilemmoma), aneurysm
- Dislocation of carpal bones
- Women > men (3 to 6:1)
- Age—40 to 60 years
- Obesity
- Caffeine, tobacco
- Alcohol—especially former abuse
- Rheumatoid arthritis, gout, pseudogout,
- Acromegaly, amyloidosis, tuberculosis
- Hypothyroidism
- Diabetes mellitus
- Renal failure