The symptomatology of carpal tunnel syndrome is quite characteristic and helps, in the majority of cases, to direct the doctor in its diagnosis.
Physical examination. An examination is performed on the sensitivity and forces of the hand and fingers, as well as manoeuvres that trigger the symptoms. These manoeuvres are:
Tinel Test. Consists of gently tapping the area of the palmar tendon with the fingers in order to provoke tingling and detect if there is inflammation of a nerve.
Phalen Test. Consists of maintaining the wrist in forced flexion for 1 minute. If there is compression of the median nerve in the carpal tunnel, tingling usually appears in the palm of the hand and in the fingers that depend on the median nerve, although the discomforts are normally produced in the tips of the fingers.
Durkan Sign. The characteristic symptoms are seen on applying pressure over the area of the palmar tendon.
Electrophysiological tests. Usually performed to measure the nerve conduction of the wrist where there is local compression of the nerve. It consists in the placing of electrodes on the hand and wrist. Small electric shocks are applied and the velocity with which the nerve impulses are transmitted is measured. Occasionally, it is complemented by an electromyogram (EMG) that consists of the introduction of a needle into the muscle innervated by the nerve that is being studied in order to measure its electrical activity. In severe chronic cases there may be fibrillations of the short abductor muscle of the thumb.
Image tests. Studies using radiology, ultrasound, or magnetic resonance can be useful to discover any unsuspected disease, to measure the size of the tunnel or visualise the nerve compression area. But at the moment diagnostic imaging is not useful for the diagnosis of carpal tunnel syndrome.
Laboratory tests There are no laboratory tests that indicate the presence of a carpal tunnel syndrome, but there are diseases, such as diabetes or hypothyroidism, which are often present when there is carpal nerve damage.
Other diseases. Such as fibromyalgia, vasculitis, or pernicious anaemia may show symptoms similar to carpal tunnel syndrome. The intervention by a general medical practitioner, rheumatologist, or neurologist helps in its diagnosis.