In the Sept. 3, 2014 issue of The Journal Fowler et al. elegantly compare the accuracy of ultrasound for confirming the clinical diagnosis of carpal tunnel syndrome with the current standard of electrodiagnostic testing. In a very well-designed trial using the validated CTS-6 patient-reported outcome tool as the reference standard, they determined 90% diagnostic specificity and 89% sensitivity for ultrasound, with a corresponding 80% specificity and 89% sensitivity for electrodiagnostic testing. In this experimental design, high-volume practitioners administered the diagnostic tests so there is a caveat: the reliability of both ultrasound and electrodiagnostic testing is probably dependent on practitioner experience.
The study clearly shows that in patients with positive CTS-6 results and no signs of radiculopathy or polyneuropathy, ultrasound is as good as electrodiagnostic testing at confirming the diagnosis–and more comfortable for the patient. But the findings also beg a question: Do we really need any adjunctive testing for this group of patients, who I think represent the majority of those presenting with carpal tunnel syndrome symptoms? Wouldn’t the patient-reported symptoms and physical-exam results that are captured in the CTS-6 be sufficient?
I believe most of us agree that a careful history and physical exam should always form the basis for most diagnoses in orthopaedics. Carpal tunnel syndrome has a well-clarified anatomic basis and a very effective surgical treatment. There may occasionally be a role for conservative care but it is often ineffective, and patients should be counseled carefully about the limited efficacy of splints and corticosteroid injections. For most patients in whom this diagnosis is strongly suggested by history and exam, advanced testing is not needed and only adds to patient and system costs. By ordering these tests only for complex cases in which the diagnosis or severity of impairment is unclear, we will be improving patient outcomes while lowering the overall cost of care. That in turn will help us achieve the “triple aim” of access, good outcomes, and lower cost.