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Carpal Tunnel Syndrome
Definition: Carpal tunnel syndrome is the result of median nerve entrapment at the level of the carpus; leading to paraesthesia, pain, and occasionally asthenia of the intrinsic muscles of the hand. The median nerve bifurcates at the level of the flexor retinaculum, giving off a branch, which travels above the flexor retinaculum. As a result of this division, the symptoms of carpal tunnel syndrome are most manifest in the finger-tips of the lateral three and a half fingers.
Causes: Carpal tunnel syndrome is a consequence of confinement and subsequent entrapment of the median nerve within the carpal tunnel; such causes can be associated with direct trauma to the carpus or capal subluxations/dislocations, and fractures e.g. Colle's. Other causes can be linked with increased fluid retention such as in pregnancy, hypothyroidism, and right sided heart failure. There is also a strong association with diabetes, multiple myeloma, amyloidosis, space occupying lesions, rheumatoid arthritis and acromegaly. Occupational risk factors such as repetitive tasks and the use of vibrating tools have also been implicated in carpal tunnel syndrome.
Examination: The patient will usually present with neurological changes in the finger-tips of the lateral three and a half fingers. Carpal tunnel syndrome can occur unilaterally or bilaterally, a factor, which can help differentiate between a local or systemic aetiology. There may be intrinsic muscle atrophy and asthenia. A nocturnal aggravation in symptoms is a common trait of Carpal tunnel syndrome, with patients having to shake the symptomatic hand to relieve the symptoms.
Orthopaedic tests for carpal tunnel syndrome:
Phalen's test: instruct the patient to flex both wrists and approximate the dorsum of each hand together. Aggravation in symptoms indicates a positive.
Reverse Phalen's test: instruct the patient to extend the symptomatic wrist and grip the practitioner hand. With his free thumb the practitioner than adds pressure over the carpus of the symptomatic hand. Aggravation in symptoms indicates a positive.