Carpal Tunnel Syndrome is the painful peripheral neuropathy that results from the compression of the median nerve at the wrist. The increased pressure within the unyielding carpal tunnel leads to symptoms from the median nerve. It occurs in 1.5 to 5% of the general population (affecting women three times more than men), and is the most common (90%) of the entrapment syndromes.
Carpal tunnel syndrome manifests itself in a variety of symptoms such as:
- Numbness, tingling feeling or/and burning at the areas supplied by the sensory branches of the median nerve (thumb, index finger, middle finger, and the radial side of the ring finger)
- Dull pain in the hand that can spread from the wrist to the elbow or even the shoulder
- Functional limitation (weakness, difficulty in forming a punch, decrease in the ability to tighten) in the affected hand
- Sensory disturbances of which the most common is paresthesia (abnormal sensation of discomfort) and loss of sensation in the areas supplied by the median nerve
- Sensation of cold fingers and hand swelling
- Shaking the hand often provides relief
- Muscular atrophy at the thenar (the fleshy mass on the palm of the hand at the base of the thumb)
The symptoms worsen during the night (often waking the patient).
The pathophysiology of the syndrome is linked to mechanical stress and ischemia of the nerve due to insufficient blood flow (compression of the vasa vasorum), which leads to damage (demyelination) of the median nerve.
The risk of occurrence of carpal tunnel syndrome relies on a combination of clinical situations:
- Anatomical anomalies in the carpal tunnel
- Mechanical injury (increased pressure from repeated bending movements of the wrist)
- Inflammatory causes (rheumatoid arthritis, tenosynovitis), leading to swelling and increased pressure within the carpal tunnel
- Chronic compression of structures causes changes in the connective tissue and adhesions that lead to interference in the regular movement of tendons in the carpal tunnel
- Metabolic factors (hypothyroidism, amyloidosis, menopause, chronic renal failure)
- Neuropathy relevant to diabetes mellitus, alcoholism
- Pregnancy (50% of pregnant women report symptoms of CTS which in most cases disappear after giving birth)
Diagnostic investigation of the syndrome is based on the medical history (onset, spreading of the pain, nocturnal paresthesia), clinical examination (sensation changes, muscular strength, muscular atrophy at the thenar, Phalen test), and study of electrical conductivity in the upper limbs (electromyogram-EMG & nerve conduction study-NCS). The role of the MRI of the wrist and the use of ultrasound remain a valuable assistance in special cases or in cases of non-identification.
The natural course of the disease varies. Symptoms may worsen with time or disappear and reoccur at intervals. However, without treatment, 1/3 of patients report a complete disappearance of symptoms within 6 months.
Conservative treatments for carpal tunnel syndrome are under evaluation. Choices include: pharmaceutical treatment with anti-inflammatory drugs, use of a wrist splint, local injection of corticosteroids, ultrasound therapy, wrist-stretching exercises, and acupuncture. 2/3 of patients report a significant improvement in symptoms for at least a year by the use of the conservative method. Alternatively, surgical intervention (section of the transverse carpal ligament using an open or endoscopic access method) is considered a final solution (in 3/4 of the patients) even if in some cases long-term rehabilitation is required.
Treatment of carpal tunnel syndrome with acupuncture
Even though existing analyses conclude that the evidence is not sufficient, the most recent studies suggest the value of acupuncture in alleviating symptoms (R. Schulman 2008, C.P. Yang 2009, W. Kumnerddee 2010, V. Napadow 2010, Sim 2011, A. Moghtaderi 2011) and support the inclusion of acupuncture/electroacupuncture in protocols for the treatment of carpal tunnel syndrome.
Treatment with acupuncture in mild to moderate cases of CTS has been electrodiagnostically and clinically proven to be as effective as the oral administration of corticosteroids (C.P. Yang et al. The Clinical Journal of Pain. Vol.25(4) May 2009). It is estimated that 8 sessions of acupuncture of 30 minutes each over a period of 4 weeks is a good alternative solution to improve symptoms of carpal tunnel syndrome.