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

Table 1. Comparison of pooled sensitivities and specificities of EDX techniques to diagnose CTS.TechniquePooledsensitivity*Pooledspecificity*ABMedian sensory and mixed nerve conduction: wrist and palm segmentcompared to forearm or digit segmentComparison of median and ulnar sensory conduction between wrist andring finger0.85 †(0.83, 0.88)0.85(0.80, 0.90)C Median sensory and mixed nerve conduction between wrist and palm 0.74 †DComparison of median and ulnar mixed nerve conduction between wristand palm(0.71, 0.76)0.71(0.65, 0.77)E Median motor nerve conduction between wrist and palm 0.69 †FComparison of median and radial sensory conduction between wrist andthumb(0.64, 0.74)0.65(0.60, 0.71)G Median sensory nerve conduction between wrist and digit 0.65 †(0.63, 0.67)H Median motor nerve distal latency 0.63 †(0.61, 0.65)I Median motor nerve terminal latency index 0.62 †JComparison of median motor nerve distal latency (second lumbrical) to theulnar motor nerve distal latency (second interossei)(0.54, 0.70)0.56 ‡(0.46, 0.66)K Sympathetic skin response 0.04(0.00, 0.08)0.98 †(0.94, 1.00)0.97(0.91, 0.99)0.97 †(0.95, 0.99)0.97(0.91, 0.99)0.98 †(0.93, 0.99)0.99(0.96, 1.00)0.98 †(0.97, 0.99)0.98 †(0.96, 0.99)0.94 †(0.87, 0.97)0.98 ‡(0.90, 1.00)0.52(0.44, 0.61)*For each EDX technique to summarize results across studies, sensitivities were pooled from individual studies by calculating a weighted average. Incalculating the weighted average, studies enrolling more patients received more weight than studies enrolling fewer patients. Specificities weresimilarly pooled by calculating the weighted average. The data in the parentheses below the sensitivity and specificity values represent the lower andupper 95% confidence limits of the weighted average, respectively. Data analysis courtesy of Dr. Gary Gronseth. †There was heterogeneity betweensome of the studies (the 95% confidence intervals of the sensitivities and specificities do not overlap). This disparity may be related to differences incase definition of CTS, the use of different cut-points to define an abnormal value, and differences in the average severity of the CTS patients in thedifferent studies. ‡Results based on a single study.RECOMMENDATIONS REGARDING EDX STUDIES TOCONFIRM A CLINICAL DIAGNOSIS OF CTSThe recommendations below are identical to thosemade and endorsed in 1993 by the AmericanAcademy of Neurology, 3 the American Academyof Physical Medicine and Rehabilitation, 4 and theAmerican Association of ElectrodiagnosticMedicine 5 with the clarification ofrecommendation 1 and 2a and the addition of 2cbased on new evidence reviewed in the secondCTS Literature Review. 2In patients suspected of CTS, the following EDXstudies are recommended (See Table I forsensitivity and specificity of Techniques A–K):1. Perform a median sensory NCS across thewrist with a conduction distance of 13 cm to14 cm (Technique G). If the result isabnormal, comparison of the result of themedian sensory NCS to the result of a sensoryNCS of one other adjacent sensory nerve inthe symptomatic limb (Standard).2. If the initial median sensory NCS across thewrist has a conduction distance greater than 8cm and the result is normal, one of thefollowing additional studies is recommended:a. comparison of median sensory or mixednerve conduction across the wrist over ashort (7 cm to 8 cm) conduction distance(Technique C) with ulnar sensory nerveconduction across the wrist over the sameshort (7 cm to 8 cm) conduction distance(Technique D) (Standard), orb. comparison of median sensory conductionacross the wrist with radial or ulnarsensory conduction across the wrist in thesame limb (Techniques B and F)(Standard), orc. comparison of median sensory or mixednerve conduction through the carpaltunnel to sensory or mixed NCSs ofproximal (forearm) or distal (digit)AAEM Practice Topic MUSCLE & NERVE June 2002 921