Carpal Tunnel Syndrome

The carpal tunnel contains 9 flexor tendons and the median nerve. The 9 flexor tendons are:

affecting approximately 3% of the general adult population.
Women are three times more likely to have CTS than men
prevalence and severity increase with age.
Work-related activities that require a high degree of repetition and force or use of hand-operated vibratory tools significantly increase the risk of CTS

Risk factors and causes of CTS

*Fluid retention*	*Inflammation of structures within/around the carpal tunnel*	*Space occupying lesions*	*Other conditions*
Pregnancy Menopause Obesity	Repetitive strain injury causing tendinopathy (overuse in jobs such as gardening, assembly line work and use of vibrational power tools) Inflammatory arthropathy (e.g. rheumatoid arthritis)	Ganglion cysts Osteophytes (in osteoarthritis) Previous wrist fractures/ trauma may also mechanically reduce the space within the carpal tunnel	Diabetes mellitus Hypothyroidism Smoking advanced age chronic renal failure alcoholism

Symptoms

The hallmarks
- pain and paresthesias in the distribution of the median nerve
  - palmar aspect of the thumb, index and middle fingers, and radial half of the ring finger
- Flick Sign:
  - Woken up with symptoms and shake out their hand to provide relief.
  - 93% sensitive and 96% specific for CTS
Symptoms can vary widely and occasionally localize to the wrist or the entire hand, or radiate to the forearm or rarely the shoulder.
provoking factors
- repetitive wrist flexion or hand elevation, such as driving or holding a telephone for extended periods.
Because sensory fibers are more susceptible to compression than motor fibers, paresthesias and pain usually predominate early in the course of CTS.
severe cases: motor fibers are affected, leading to weakness of thumb abduction and opposition.
- Patients may describe difficulty holding objects, opening jars, or buttoning a shirt. Disappearance of pain is a late finding that implies permanent sensory loss.

Physical exam

thenar atrophy
carpal tunnel compression test (Durkan’s test)
- performed by pressing thumbs over the carpal tunnel and holding pressure for 30 seconds.
- onset of pain or paresthesia in the median nerve distribution within 30 seconds is a positive result.
Phalen test
- wrist volar flexion against gravity for ~60 sec produces symptoms
- less sensitive than Durkin compression test
Tinel’s test
- provocative tests performed by tapping the median nerve over the volar carpal tunnel

A hand symptom diagram can be a useful tool in diagnosing carpal tunnel syndrome.

Diagnosis
- EMG (electromyography) and Nerve Conduction Velocities
  - Electrodiagnostic studies have a sensitivity of 56% to 85% and specificity of 94% to 99% for CTS.
  - Results may be normal in up to one-third of patients with mild CTS.
  - Therefore, these studies should be reserved for confirming CTS in atypical cases and excluding other causes.

ULTRASONOGRAPHY
- The cross-sectional area of the median nerve is closely correlated with CTS symptoms and severity
- cross-sectional area > 9 mm2 is 87.3% sensitive and 83.3% specific for CTS.1

OTHER TESTS
- Plain radiography may be useful if structural abnormalities, such as bone or joint disease, are suspected. Magnetic resonance imaging is not generally indicated. Laboratory testing for comorbidities, such as diabetes or hypothyroidism, may be considered if there are other signs suggesting disease.

Treatment
- Nonoperative
  - NSAIDS
  - night splints (good for patients with nocturnal symptoms only)
  - activity modification (avoid aggravating activity)
  - steroid injections
    - 80% have transient improvement of symptoms (of these 20% remain symptom-free at one year)
    - failure to improve after injection is poor prognostic factor
- Operative
  - carpal tunnel release
  - grip strength is expected to return to 100% preoperative levels by 12 weeks postop
  - rate of continued symptoms at 1+ year is 2% in moderate and 20% in severe CTS
  - improved patient reported-outcomes with surgery at 6 and 12 months as compared to splinting, NSAIDs/therapy, and a single steroid injection

	In the classic pattern, symptoms affect at least two of digits 1, 2, or 3. It includes symptoms in the fourth and fifth digits, wrist pain, and radiation of pain proximal to the wrist, but excludes symptoms on the palm or dorsum of the hand.
	The probable pattern has the same symptom pattern as the classic pattern, except palmar symptoms are possible unless confined solely to the ulnar aspect.
	In the unlikely pattern, no symptoms are present in digits 1, 2, or 3