PCL 5- Carpal Tunnel Syndrome Investigation

Carpal Tunnel Investigations

An early diagnosis and appropriate treatment may aid a rapid return to normal function and avoid permanent damage to the median nerve.

Some doctor's feel that the clinical symptoms and the physical signs that they elicit are so classic of carpal tunnel syndrome they will offer the patient treatment on this basis

If there is any suggestion of any cause for the carpal tunnel syndrome this may be investigated.
1. Blood tests to exclude diabetes, thyroid problems, rheumatoid arthritis.
2. Plain x-rays can be obtained if there is a suggestion of an old bone abnormality.

The most common investigation for carpal tunnel syndrome:

Nerve conduction studies/ Electroneurography (ENG)

These are electro-diagnostic tests. In this investigation small electrodes are placed on the hand, wrist and tips of fingers. Small electrical current shocks are then applied to the electrodes and the speed in which the nerve travels through the carpal tunnel can be recorded. This can be compared with the opposite side or if a patient has symptoms in both sides, can be compared with a large database of normal individuals that is stored centrally

85% sensitivity and specificity greater than 95% for diagnosing CTS.

Electromyography (EMG)

Very occasionally further tests can be performed inserting tiny needles into the muscles of the base of the thumb to assess muscle damage. However this is rarely undertaken for a classic carpal tunnel syndrome.

Useful in some cases but is not as sensitive as ENG

Ultrasonography
This is being used increasingly as a confirmatory test. Enthusiasts cite its wide availability, lower cost, noninvasiveness, and shorter examination time than electrophysiological studies. Ultrasound views of the median nerve show widening at the inlet of the carpal tunnel or flattening along the length of the tunnel

MRI scan- this can be used as an alternative to ultrasonography and when electrophysiological studies are ambiguous.7

These are useful in patients whose clinical features yield a high index of suspicion for carpal tunnel syndrome (CTS) but who fail to respond to first-line treatment.9
There is increasing evidence that nerve conduction studies performed before treatment can give a guide as to future outcomes of further surgery if initial surgery has not been successful.