Two-Point Discrimination in the Use of Upper Extremity Nerve Function in the AMA Guides
Richard Katz
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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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