Carpal Tunnel Syndrome: Impairment Rating by the AMA Guides, Fifth Edition

Abstract

Abstract The pain, numbness, and paresthesias of carpal tunnel syndrome generally are intermittent and are felt in the wrist, hand, thumb, and fingers, often in a distribution approximating that of the median nerve. No specific physical examination exists for carpal tunnel syndrome, and, in the impairment rating assessment, the physical examination focuses on detecting signs of permanent nerve damage (decreased sensation and thenar weakness on opposition). According to the AMA Guides to the Evaluation of Permanent Impairment, (AMA Guides), provocative tests have no role in impairment rating. The AMA Guides, Fifth Edition, requires nerve conduction testing (NCT), even in “believable” instances, but no uniform definition of an abnormal NCT exists and examiners should realize the uses and limits of NCT. For example, if the NCT is normal, the symptoms, even if believable, do not rise to the level of an impairment. Impairment assessment must take place when the patient is at maximum medical improvement. If the NCT is grossly abnormal (axon loss) and/or degenerative changes are present on needle electromyography, and if physical exam shows sensory and/or thenar weakness, the examiner can use tables in the AMA Guides to rate the disability, combining sensory and motor impairments as appropriate. A one-page sidebar in this issue of The Guides Newsletter addresses the causes of carpal tunnel syndrome.