Examining Hand Strength in Presence of Carpal Tunnel Syndrome -
Rating Tip of the Week

Muscle strength testing is discussed in the Guides 5th ed. in Chapter 16, section 16.5b Impairment Evaluation Methods, Grading Motor Deficits and Loss of Power (page 483 – 486). The Guides State:

Clinical examination of the upper extremity demands precise anatomic knowledge to properly select the muscle tests that correlate to the specific nerve structure(s) involved.

Abduction of the thumb is provided by both the abductor pollicis brevis and abductor pollicis longus muscles. The abductor pollicis brevis is innervated by the median nerve, whereas the longus is innervated by the posterior interosseous nerve. Therefore, abduction strength testing of the thumb will not isolate median nerve function.

In order to precisely assess median nerve function, strength testing should focus on the opponens pollicis muscle. The technique described was discussed in the January/February 2006 edition of The Guides Newsletter and was authored by James B. Talmage, MD, Christopher R. Brigham, MD, and Charles N. Brooks, MD.

This muscle (opponens pollicis) is assessed by having the examinee adduct the thumb metacarpal and oppose the volar pulp of the distal phalanges of thumb and little finger. The evaluator then applies force in an attempt to return the thumb to its anatomic position.

Proper examination of the thenar muscles will result in a more accurate assessment of strength in the presence of CTS, and thus, a more reliable impairment rating.