Investigation of CTS

WORK RELATED CTS

CTS are seen in many work situations requiring rapid finger and wrist motion under load, such as meat workers and process workers. A type of flexor tenosynovitis develops and thus nerve compression in the tight tunnel. It is advisable to arrange confirmatory investigations by nerve conduction studies and electromyography for this work-induced overuse disorder.

Simple clinical tests

To assist and confirming the diagnosis (relatively low sensitvity and specificity).

The tinel’s test

· Hold the wrist in a neutral or flexed position and tap over the median nerve at the flexor surface (anterior surface) of the wrist. This should be over the retinaculum just lateral to the palmaris longus tendon (if present) and the tendons of flexor digitorium superficialis.

· A positive Tinel’s sign produces a tingling sensation (usually without pain) in the distribution of the median nerve.

The phalen’s test

· The patient approximates the dorsum of both hands, one to the other, with wrists maximally flexed and fingers pointing downwards.

· This position is held for 60 seconds.

· The positive test reproduces tingling and numbness along the distribution of the median nerve.

Electrodiagnostic Test

To analyze the electric waveforms of nerves and muscles to detect median nerve compression in the carpal tunnel are the best methods for confirming a diagnosis of CTS at this time

Nerve conduction studies

· To perform nerve conduction studies, surface electrodes are first fastened to the hand and wrist.

· Small electric shocks are then applied to the nerves in the fingers, wrist, and forearm to measure the speed of conduction of sensory and motor nerve fibers.

· In suspected cases of CTS, nerve conduction tests can identify over 85% of true carpal tunnel syndrome cases and eliminate 95% of those that are not true CTS. They are less accurate in identifying mild CTS. Patients should be sure their practitioners perform tests that compare a number of internal responses--not just routine testing that records only the responses of thenar muscles (located in the palm at the base of the thumb) and second or third fingers. These tests can also detect causes of symptoms that mimic CTS but should be attributed to other problems, such as pinched nerves in the neck or elbow or thoracic outlet syndrome.

electromyography

· To perform electromyography, a fine, sterile, wire electrode is inserted briefly into a muscle and the electrical activity is displayed on a viewing screen.

· Electromyography can be quite painful and is less accurate than nerve conduction. Some experts question, in fact, whether it adds any valuable diagnostic information. They suggest it be limited to unusual cases or when other tests indicate that the condition is aggressive and may increase the risk for rapid, significant injury.