Practice Parameter and Literature Review of the Usefulness of ...

Practice Parameter: Carpal Tunnel Syndrome(Table 2).The AAEM recommends that studies which compare thesensitivity and specificity studies of NCSs and needle EMGto the sensitivity and specificity of other tests proposed forthe diagnosis of CTS use the clinical diagnosis of probableCTS as defined in Table 2. These alternative diagnosticstudies include the following: quantitative cutaneoussensory testing of perception threshold for vibration, 2-pointdiscrimination, touch, warmth, cold, and electriccurrent; 21,22,120,153,160,168,247 hand symptom diagrams; 122,123,124magnetic resonance imaging and computed tomographicstudies of the carpal tunnel; 16,17,99,169 thermography; 100,170,240wrist ratio; 90 provocation of symptoms by ultrasound; 172 andcarpal tunnel pressure measurements. 78,212Both the first and second AAEM CTS Literature Reviewsrecommended that outcome studies should be performed toassess the harms, benefits, and costs of performing NCSsand needle EMG in patients with symptoms suggestive ofCTS.The AAEM recommends that future outcome studies oftreatment of CTS use the clinical diagnoses of definite CTS(as defined in Table 2) with EDX studies of high sensitivityand specificity for the diagnosis of CTS performed by aspecially trained physician, i.e., median mixed nerve palmarstudies and/or comparison of median to ulnar and/or radialsensory NCS in the same hand.The AAEM CTS Task Force has addressed future researchprinciples over future research topics (except for outcomestudies) because the Task Force concluded that futureresearch studies need to meet these principles (1) to providereliable and reproducible data to evaluate the usefulness ofEDX studies to confirm the clinical diagnosis of CTS and(2) permit comparison of the relative utility of differentEDX studies for that purpose.It is recommended that the AAEM review this report every5 years and update the report as necessary.DISCUSSIONThis report includes 2 recommendations in addition to thosein the 1993 CTS Literature Review to improve futureclinical research studies of the usefulness of EDX studies toconfirm the clinical diagnosis of CTS.1. This report provides a new consensus based set ofinclusion and exclusion criteria for the clinicaldiagnosis of CTS according to the certainty of thediagnosis: possible CTS, probable CTS, anddefinite CTS (Table 2). We recommend the criteriafor the diagnosis of probable CTS be used infuture studies of EDX tests to reduce the possibilityof selection bias, to provide a more uniformpopulation of CTS patients, and to provide a validscientific basis for comparison of the results offuture studies from different laboratories. Thissuggestion is a refinement on the originalrecommendation made in the 1993 CTS LiteratureReview.2. Sackett and colleagues 217 and others haverecommended that clinical research studies ofdiagnostic tests (including EDX studies) beperformed with the physician performing andinterpreting the diagnostic tests blinded to thediagnosis of the subject with the goal ofeliminating observer bias. There is a solid body ofclinical evidence and experience which indicatesthat NCSs are useful to confirm the diagnosis ofCTS, a body of evidence similar in weight to theclinical evidence that radiographs are useful toidentify fractures of the limb bones andelectrocardiograms are useful to identifymyocardial ischemia and infarction. Nevertheless,it is worth performing future evaluations of EDXstudies in CTS with the examiner blinded to theclinical diagnosis of the subject as the next step toestablishing the validity of these conclusionsbeyond a reasonable doubt. In fact, some clinicalinvestigators have already begun to performevaluations of NCSs in CTS in a blinded fashion(Salerno and colleagues 218,219 and Werner andcolleagues 263 ).In the 1993 AAEM CTS Literature Review, it wasrecommended that an outcome study be performed to assessthe harms, benefits, and costs of performing NCSs andneedle EMG in patients with symptoms suggestive of CTS.In 1994, Boniface and colleagues 20 published a prospectivestudy from England which demonstrated that NCS/EMGstudies were useful and cost effective in management ofpatients suspected of CTS. 20 In addition, the AAEM hasencouraged additional outcome studies including thepublication of guidelines for outcome studies inneuromuscular diseases including CTS. 108 The AAEMResearch and Education Foundation has recently funded aprospective outcome study of 400 patients to evaluate theusefulness of EDX studies in the evaluation andmanagement of patients with symptoms suggestive of CTS.It is recommended that outcome studies continue to be apriority for future clinical research in the diagnosis andmanagement of CTS and other neuromuscular diseases.INTERFACE WITH AAEM GUIDELINESIn 1999, the AAEM republished guidelines based uponexpert opinion and first published in 1992 for the evaluationof CTS patients. 2,4 The AAEM Guidelines recommend thefollowing EDX studies: (1) median sensory or mixed NCSto include determination of (a) the amplitude and (b) peaklatency or onset latency or CV of the segment of the mediannerve passing through the carpal tunnel; (2) median motorMuscle & Nerve Supplement X 2002 S957