Aanem Practice Topic Evidence-based Guideline: Neuromuscular Ultrasound for the Diagnosis of Carpal Tunnel Syndrome

Introduction: The purpose of this study was to develop an evidence-based guideline for the use of neuromuscular ultrasound in the diagnosis of carpal tunnel syndrome (CTS). Methods: Two questions were asked: (1) What is the accuracy of median nerve cross-sectional area enlargement as measured with ultrasound for the diagnosis of CTS? (2) What added value, if any, does neuromuscular ultrasound provide over electrodiagnostic studies alone for the diagnosis of CTS? A systematic review was performed, and studies were classified according to American Academy of Neurology criteria for rating articles of diagnostic accuracy (question 1) and for screening articles (question 2). Results: Neuromuscular ultrasound measurement of median nerve cross-sectional area at the wrist is accurate and may be offered as a diagnostic test for CTS (Level A). Neuromuscular ultrasound probably adds value to electrodiagnostic studies when diagnosing CTS and should be considered in screening for structural abnormalities at the wrist in those with CTS (Level B). Muscle Nerve 46: 287–293, 2012 Carpal tunnel syndrome (CTS) is a combination of signs and symptoms resulting from mononeuropathy of the median nerve as it passes through the rigid carpal tunnel in the wrist. It is a common condition that affects 2.7% of the general population and results in health-care costs exceeding $500 million annually in the USA. CTS is typically diagnosed by history and physical examination, and electrodiagnostic studies (nerve conduction studies and sometimes electromyography) are used to confirm the presence of a median mononeuropathy. Electrodiagnostic studies have limitations; they are uncomfortable and do not directly assess the anatomy of the median nerve and its surrounding structures. Over the past 20 years, neuromuscular ultrasound has been introduced into electrodiagnostic laboratories as a complement to nerve conduction studies and electromyography for the diagnosis of a variety of nerve and muscle conditions. CTS is the condition most commonly studied with neuromuscular ultrasound, and individuals with CTS have displayed ultrasonographic evidence of focal enlargement of the median nerve at the wrist. In addition, neuromuscular ultrasound can identify causes of median mononeuropathy at the wrist and structural anomalies that could not be detected with electrodiagnostic studies alone, such as compressive cysts, tumors, and vessels. This evidence-based guideline was designed to address 2 critical questions regarding the use of neuromuscular ultrasound for the diagnosis of CTS. First, what is the accuracy of median nerve cross-sectional area enlargement, as measured with ultrasound, for the diagnosis of CTS? Second, what added value, if any, does neuromuscular ultrasound provide over electrodiagnostic studies alone for the diagnosis of CTS? DESCRIPTION OF THE ANALYTIC PROCESS The American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM) convened an expert panel of physicians specializing in neurology, physical medicine and rehabilitation, and radiology, selected to represent a broad range of expertise related to neuromuscular ultrasound and CTS. Some panel participants reported using Abbreviations: AAN, American Academy of Neurology; AANEM, American Association of Neuromuscular and Electrodiagnostic Medicine; CTS, carpal tunnel syndrome; NCS, nerve conduction studies Disclosures: M.S.C. receives funding from the NIH/NINDS for neuromuscular ultrasound research and royalties from Elsevier for sales of the textbook Neuromuscular Ultrasound. F.O.W. receives royalties from Elsevier for sales of the Neuromuscular Ultrasound. Approved by the AANEM Board of Directors on January 23, 2012. Correspondence to: C. French, AANEM, 2621 Superior Drive NW, Rochester, MN 55901; e-mail: [email protected] VC 2012 American Association of Neuromuscular and ElectrodiagnosticMedicine. Published online 20 March 2012 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/mus.23389