Like the diagnosis-based impairment (DBI) method and the range-of-motion (ROM) method for rating permanent impairment, the approach for rating compression or entrapment neuropathy in the upper extremity (eg, carpal tunnel syndrome [CTS]) is a separate and distinct methodology in the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Sixth Edition. Rating entrapment neuropathies is similar to the DBI method because the evaluator uses three grade modifiers (ie, test findings, functional history, and physical evaluation findings), but the way these modifiers are applied is different from that in the DBI method. Notably, the evaluator must have valid nerve conduction test results and cannot diagnose or rate nerve entrapment or compression without them; postoperative nerve conduction studies are not necessary for impairment rating purposes. The AMA Guides, Sixth Edition, uses criteria that match those established by the Normative Data Task Force and endorsed by the American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM); evaluators should be aware of updated definitions of normal from AANEM. It is possible that some patients may be diagnosed with carpal or cubital tunnel syndrome for treatment but will not qualify for that diagnosis for impairment rating; evaluating physicians must be familiar with electrodiagnostic test results to interpret them and determine if they confirm to the criteria for conduction delay, conduction block, or axon loss; if this is not the case, the evaluator may use the DBI method with the diagnosis of nonspecific pain.