AMA Guides® Newsletter - Issue Archive

Articles

1. Peripheral Nerve Entrapment Impairments Revisited: Part I

   J. Mark Melhorn, James B. Talmage, Charles N. Brooks

   Pages 3–8

   DOI: 10.1001/amaguidesnewsletters.2015.JanFeb01

   Abstract

   The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Sixth Edition, introduced the concept of diagnosis-based impairments (DBI), and a modified version of this method can be used in rating peripheral nerve injury in general (Section 5.4) and upper limb entrapment syndromes (Section 15.4f). The first portion of this article reviews the evaluation of upper extremity nerve impairment and summarizes inclusion criteria and causation correlation for carpal tunnel syndrome, Guyon's canal syndrome, cubital tunnel syndrome, anterior interosseous, Wartenberg's syndrome, and radial tunnel syndrome. Very mild nerve entrapments do exist and may fail to meet the AMA Guides criteria for impairment related to a diagnosis of nerve entrapment. Electrodiagnostic examination includes nerve conduction studies that assess the largest, most heavily myelinated axons, and needle electromyelography, which detects muscle membrane instability but not the sensory function of nerves. A case example from the AMA Guides, Sixth Edition, shows the process of permanent impairment rating in a case of carpal tunnel syndrome. Determination of impairment for peripheral nerve entrapments can be easily accomplished once one understands how to determine if the nerve under consideration from the electrodiagnostic evaluation demonstrates a conduction delay, a conduction block, or an axon loss. This establishes the test findings that usually are the only objective findings present.
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2. Two-Point Discrimination in the Use of Upper Extremity Nerve Function in the AMA Guides

   Richard Katz

   Pages 9–11

   DOI: 10.1001/amaguidesnewsletters.2015.JanFeb02

   Abstract

   This article presents a case report regarding a 34-year-old obese male who works as a chipper and grinder at a steel manufacturing mill and uses high-frequency vibratory power tools. He presents with typical complaints of carpal tunnel syndrome, including numbness in all five digits, wrist pain, nocturnal awakening/numbness, and others. Two-point discrimination (2PD) using a caliper was tested in the digits of the upper extremities and was 5 mm throughout. 2PD first appeared in the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fifth Edition, and the Sixth Edition states, “sensory deficits can be challenging to grade, since the clinical examination is based on subjective reports by the patient. Grading is based on the results of sensibility testing and two-point discrimination, to improve inter-rater reliability.” The discussion of “sensibility” involves a concept of sensory perception that is more appropriate in surgery literature than neurological literature, and the discussion of the case report in this article reflects the recent literature regarding 2PD as a measure of sensibility. The authors report that sensibility is not a simple recovery of sensory function following nerve injury but rather is a complex interaction between nerve recovery and modulation of central nervous system function in spinal cord, subcortical, and cortical structures. The authors ask if the value of 2PD in the clinical assessment of impairment has been overrated within the AMA Guides, as was range of motion in the assessment of spine impairment.
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3. Commentary on Two-Point Discrimination in the Use of Upper Extremity Nerve Function in the AMA Guides

   James B. Talmage, J. Mark Melhorn

   Pages 12–12

   DOI: 10.1001/amaguidesnewsletters.2015.JanFeb03

   Abstract

   This article responds to the previous article in this issue of The Guides Newsletter (Two-point Discrimination in the Use of Upper Extremity Nerve Function in the AMA Guides) and discusses why the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Sixth Edition, has chosen to retain the use of static two-point discrimination for both acute single incident digital nerve injury and for upper extremity focal entrapment neuropathy. The authors clarify that the AMA Guides, Sixth Edition does not use two-point discrimination as a diagnostic criterion for entrapment neuropathy such as carpal tunnel syndrome. Instead, it uses two-point discrimination as a criterion to judge severity, specifically to help select the proper integer for the rating to be assigned for the diagnosis determined by other criteria. Two-point testing is not sensitive but is specific to significant nerve impairment (ie, severity, not diagnosis), and the authors note its advantages of being familiar to most impairment examiners, having a basis in published literature, having variations of the testing protocol that help “objectify” the apparent sensory deficit, and correlating with severity. Thus, if a rating is to be done “according to the AMA Guides,” two-point discrimination remains a required and important part of assessment of the upper extremity neurologic impairment of the hand.
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4. In Recent Literature

   Christopher R. Brigham

   Pages 13–16

   DOI: 10.1001/amaguidesnewsletters.2015.JanFeb04

   Abstract

   This column presents abstracts, as published in PudMed.gov (U.S. National Library of Medicine, National Institutes of Health) that are pertinent to the evaluation of patients who are injured or ill.
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5. Q&A: Rating C1 and C2 Fractures

   Charles N. Brooks, James B. Talmage, Marjorie Eskay-Auerbach

   Pages 15–15

   DOI: 10.1001/amaguidesnewsletters.2015.JanFeb05