Practice Parameter and Literature Review of the Usefulness of Nerve Conduction Studies and Needle Electromyography for the Evaluation of Patients with Carpal Tunnel Syndrome

Orthodromic SNAPs were recorded over the median nerve using needle electrodes at the wrist and elbow after stimulation of thethumb and middle fingers. CMAPs were recorded with concentric needle electrodes placed in the endplate zone of the APB after stimulation at the wrist and elbow. NCVs were determined for 28male and 20 female normal subjects aged 16 to 62 years. There wasno significant difference in NCV between male and female subjects.There was a decrease in NCV with increasing age. No CTS patientswere studied.186. Occupational Disease Surveillance. Carpal tunnel syndrome. MMWRMorb Mortal Wkly Rep 1989;38:485-489. Background ReferenceSource: Baker, 1990.187. *Osborn JB, Newell KJ, Rudney JD, Stoltenberg JL. Carpal tunnelsyndrome among Minnesota dental hygienists. J Dent Hyg1990;64(2):79-85. Criteria Met (2/6: 1,2) Source: Medline Search.188. Padua L, Lo Monaco M, Valente EM, Tonali PA. A usefulelectrophysiologic parameter for diagnosis of carpal tunnel syndrome.Muscle Nerve 1996;19:48-53. Criteria Met (6/6: 1,2,3,4,5,6). Source:Medline Search. Abstract: In 43 patients (50 hands) with clinicalmanifestations of mild-moderate CTS and 36 healthy volunteers (40hands), orthodromic sensory nerve conduction velocity (SNCV) wasmeasured with surface electrodes in the median nerve between thethird digit and palm and between the palm and wrist. These figureswere used to calculate the ratio of distal to proximal conduction(distoproximal ratio). All 90 hands were also subjected to other nerveconduction studies used for diagnosis of CTS. All control handspresented distoproximal ratios less than 1.0 reflecting higherconduction rates in the proximal segment. In contrast, 49 of 50 CTShands (98%) presented reversed ratios (>1.0) indicating compromisedproximal conduction. The sensitivity of this test was significantlygreater than that of other methods evaluated, including comparativestudies and segmental study of the palm-wrist portion of the mediannerve. Segmental study of median SNCV with calculation of thedistoproximal ratio is a sensitive technique for diagnosis of CTS inpatients with normal findings in standard nerve conduction studies.Note: The author indicated by correspondence that the mean ± SD forthe Control DML in Table 1 should read 3.2 ± 0.4 and not 3.2 ± 0.8 aspublished.189. Padua L, LoMonaco M, Gregori B, Valente EM, Padua R, Tonali P.Neurophysiological classification and sensitivity in 500 carpal tunnelsyndrome hands. Acta Neurol Scand 1997;96:211-217. Criteria Med(6/6: 1,2,3,4,5,6) Source: Medline Search. Abstract: Prospective studyof 500 hands (379 patients) with clinical diagnosis of CTS symptoms.Normal values from the same laboratory previously published (Padua,1996). In the 500 CTS patients, DML was prolonged (55%), medianorthodromic sensory latency was prolonged (D2, 74%; D3, 67%). Ofthe remaining 117 patients with normal DML and medianorthodromic sensory studies over 14 cm, the median sensory palm-wrist NCV over 8 cm was abnormal in 21% and the distoproximoratio of the median palm and digit segments was abnormal in 87%.190. Palliyath SK, Holden L. Refractory studies in early detection of carpaltunnel syndrome. Electromyogr Clin Neurophysiol 1990;30:307-309.Criteria Met (5/6: 1,3,4,5,6) Source: Medline Search. Abstract: Usingpaired stimuli and varying the inter-stimulus interval, the absoluterefractory period (ARP) and relative refractory period (RRP), weredetermined in 10 patients with mild electrophysiologic changessuggestive of CTS. They found that the sensory RRP was sensitive indiagnosing early CTS.191. *Pavesi G, Olivieri MF, Misk A, Mancia D. Clinical-electrophysiological correlations in the carpal tunnel syndrome. Ital JNeurol Sci 1986;7:93-96. Criteria Met (3/6: 2,3,5) Source: MedlineSearch.192. Pease WS, Cannell CD, Johnson EW. Median to radial latencydifference test in mild carpal tunnel syndrome. Muscle Nerve1989;12:905-909. Criteria Met (4/6: 1,3,5,6) Source: Medline Search.Abstract: The following techniques were studied: (a) antidromic DSLmedian radial differences to the thumb, (b) antidromic DSL afterstimulation at the wrist and recording from the third digit, (c) medianmid-palmar DSL compared as a ratio of the wrist to middle fingerDSL, (d) median ulnar DSL latency difference between the ulnar Practice Parameter: Carpal Tunnel Syndrome Muscle & Nerve Supplement X 2002 S971SNAP recorded from the little finger after stimulation at the wrist and the median DSL after stimulation at the wrist and recording from themiddle finger, and (e) median motor DML after recording from the APB after stimulation at the wrist. Three hundred thirty-three symptomatic hands in 262 patients were initially evaluated withsubgroups of patients with CTS evaluated with different tests. The median radial DSL difference and median ulnar DSL difference were most likely to be abnormal followed by median DSL then the palm-to-wrist DSL latency ratio and lastly the DML.193. Pease WS, Cunningham ML, Walsh WE, Johnson EW. Determiningneurapraxia in carpal tunnel syndrome. Am J Phys Med Rehabil1988;67:117-119. Criteria Met (5/6: 1,3,4,5,6) Source: MedlineSearch. Abstract: With needle stimulation at the wrist and midpalm,CMAPs were recorded over the APB in 25 CTS patients and 23healthy asymptomatic persons. They found a significant difference inthe amplitude of the CMAP in the CTS group when compared to thecontrol group. They propose that this is evidence for conduction block(neurapraxia) in CTS.194. Pease WS, Lee HH, Johnson EW. Forearm median nerve conductionvelocity in carpal tunnel syndrome. Electromyogr Clin Neurophysiol1990;30:299-302. Criteria Met (4/6: 1,3,4,5) Source: Medline Search.Abstract: The NCV of the median nerve in the forearm wasdetermined by 2 methods: (a) stimulation in the forearm andrecording the nerve action potential at the wrist, and (b) stimulation atthe wrist and elbow with recording over the APB, in 21 CTS patientsand 16 control subjects. They found that the forearm NCV wasslowed in the CTS group using either technique. The authors haveproposed that this suggest that there is proximal nerve dysfunction asa result of median nerve compression in the carpal tunnel.195. *Peterson GW, Will AD. Newer electrodiagnostic techniques inperipheral nerve injuries. Orthop Clin North Am 1988;19:13-25.Criteria Met (0/6) Source: Narkis, 1990.196. *Phalen GS. The carpal tunnel syndrome: clinical evaluation of 598hands. Clin Orthop 1972;83:29-40. Background Reference. Source:Katz 1990 (J Rheumatology).197. *Phalen GS. The carpal tunnel syndrome: seventeen years’experience in diagnosis and treatment of 654 hands. J Bone Joint Surg1966;48:211-228. Criteria Met (1/6: 2) Source: Meyers, 1989.198. Phalen GS, Gardner WJ, LaLonde AA. Neuropathy of the mediannerve due to compression beneath the transverse carpal ligament. JBone Joint Surg 1950;32-A:109-112. Background Reference. Source:Braun, 1989.199. Plaja J. Comparative value of different electrodiagnostic methods incarpal tunnel syndrome. Scan J Rehabil Med 1971;3:101-108. CriteriaMet (4/6: 1,3,5,6) Source: Joynt, 1989. Abstract: The followingtechniques were studied: (a) CMAP potentials were recorded afterstimulation at the wrist and recording with coaxial needle electrodes,(b) orthodromic SNAPs with stimulation over the index finger andrecording with surface electrodes at the wrist, (c) needle EMG using acoaxial needle, (d) strength/duration curves and chronaxy. Fifty-sixcases of CTS and 20 normal subjects were evaluated. Sensorylatencies were more likely to be abnormal than the other techniquesmeasured.200. Preston DC, Logigian EL. Lumbrical and interossei recording incarpal tunnel syndrome [see comments]. Muscle Nerve 1992; 15:1253-1257. Criteria Met (5/6: 1,3,4,5,6) Source: Medline Search.Abstract: Median motor studies are commonly “normal” in mildcarpal tunnel syndrome (CTS). This reflects either the sparing ofmotor compared to sensory fibers, or the inability of conventionalstudies to detect an abnormality. A novel approach to demonstrateearly motor fiber involvement in CTS is the placement of the sameactive electrode lateral to the third metacarpal, allowing recordingfrom the second lumbrical or the deeper interossei, when stimulatingthe median or ulnar nerves at the wrist, respectively. We comparedthe difference between these latencies in 51 normal control hands to107 consecutive patient hands referred with symptoms and signssuggestive of CTS, who were subsequently proven to haveelectrophysiologic CTS by standard nerve conduction criteria. Aprolonged lumbrical-interossei latency difference (>0.4 ms) wasfound to be a sensitive indicator of CTS in all patient groups. It wasalso helpful in patients with coexistent polyneuropathy, wherelocalization of median nerve pathology at the wrist was otherwisedifficult.201. *Preston DC, Ross MH, Kothari MJ, Plotkin GM, Venkatesh S, Logigian EL. The median-ulnar latency difference studies arecomparable in mild carpal tunnel syndrome. Muscle Nerve 1994; 17: 1469-1471. Criteria Met (2/6: 1,3). Source: Medline Search. Abstract: Compares sensitivity 159 patients of orthodromic palm-wrist mixedpalmar median-ulnar peak latency difference with normal <0.4 ms, antidromic wrist-D4 sensory median-ulnar onset latency difference with normal <0.5 ms, and the second lumbrical/interossei motor withnormal <0.5 ms. See discussion of benefits of techniques anddiagrams of electrode placements and line drawings of electrode andstimulator placement.202. Preswick G. The effect of stimulus intensity in motor latency in carpaltunnel syndrome. J Neurol Neurosurg Psychiatry 1963;26:398-401.Criteria Met (4/6: 1,3,5,6) Source: Loong, 1971. Abstract: Withstimulation at the wrist and coaxial needle electrode recording fromthe APB, DMLs were recorded at super-maximal stimulation andthreshold stimulation in 29 CTS hands from 25 patients and 25control subjects. Over 80% of the patients were identified with anabnormality either with super-maximal stimulation or thresholdstimulation. Threshold stimulation was more sensitive than super-maximal stimulation.203. Read RL. Stress testing in nerve compression. Hand Clin 1991;7:521-526. Criteria Met (1/6: 3). Source: Medline Search. Comment:Inspection of the tracings in the article indicates that the non-physician author changed the sweep speed and gain during therecordings which casts doubt on the accuracy of the conclusions andconfounds the reproducibility of the measurements.204. Redmond MD, Rivner MH. False positive electrodiagnostic tests incarpal tunnel syndrome. Muscle Nerve 1988;11:511-518. Criteria Met(4/6: 1,3,5,6) Source: Medline Search. Abstract: Several techniqueswere evaluated in a normal population using literature norms to assessfor specificity in 100 hands of 50 normal subjects. Fifteen percent ofthe hands (30% of people) exhibited an abnormal median-to-ulnarsensory amplitude ratio, 8% of hands (14% of people) had abnormalresidual latencies, and 4% of hands (8% of people) had prolongedmedian-ulnar palm to wrist latency (8 cm) differences. Theysuggested a more conservative abnormality of >0.5 ms betweenmedian and ulnar nerve for midpalm stimulation to avoid falsepositive tests for CTS. No CTS patients were studied.205. Rempel D, Evanoff B, Amadio PC, de Krom M, Franklin G,Franzblau A, Gray R, Gerr F, Hagberg M, Hales T, Katz JN, PranskyG. Consensus criteria for the classification of carpal tunnel syndromein epidemiologic studies. Am J Public Health 1998;88:1447-1451.Source: Medline Search. Background Reference. Abstract: Criteriafor the classification of carpal tunnel syndrome for use inepidemiologic studies were developed by means of a consensusprocess. Twelve medical researchers with experience in conductingepidemiologic studies of carpal tunnel syndrome participated in theprocess. The group reached agreement on several conceptual issues.First, while there is no perfect gold standard for carpal tunnelsyndrome, the combination of electrodiagnostic study findings andsymptom characteristics will provide the most accurate informationfor diagnosis of carpal tunnel syndrome. Second, use of onlyelectrodiagnostic study findings to diagnose CTS is notrecommended. Finally, specific combinations of symptomcharacteristics and physical examination findings may be useful todiagnose CTS but are likely to result in greater misclassification ofpatients than the combination of finding on the clinical history and theresults of electrodiagnostic studies.206. Repaci M, Torrieri F, Di Blasio F, Uncini A. Exclusiveelectrophysiological motor involvement in carpal tunnel syndrome.Clin Neurophysiol 1999; 110: 1471-1474. Criteria Met (2/6: 3,5)Source: Medline Search.207. Resende LA, Adamo AS, Bononi APO, Castro HA, Kimaid PA,Fortinguerra CH, Schelp AO. Test of a new technique for thediagnosis of carpal tunnel syndrome. J Electromyog Kinesiol2000;10:127-133. Criteria Met (4/6: 1,3,5,6) Source: Medline Search.Abstract: Study of 55 CTS hands (32 patients) compared to 40 normalhands (20 normal subjects) of the difference between the medianmotor distal latency to the second lumbrical muscle and the ulnarmotor distal latency to the interossei muscle. The test was moresensitive to identify CTS than measurement of the median motordistal latency to the APB. Practice Parameter: Carpal Tunnel Syndrome S972 CTS Literature Review© 2002 American Association of Electrodiagnostic Medicine208. Resende LA, Alves RP, Castro HA, Kimaid PA, Fortinguerra CR, Schelp AO. Silent period in carpal tunnel syndrome. Electromyogrand Clin Neurophys 2000;40:31-36. Criteria Met (4/6: 1,3,5,6) Source: Medline Search. Abstract: There was no correlation between the silent period alterations and the severity of the CTS in 20 hands of20 CTS patients compared to 20 normal subjects. 209. *Rivner MH. Carpal tunnel syndrome: a critique of “newer” nerve conduction techniques. In: AAEM 1991 Course D: Focal peripheralneuropathies: selected topics. Rochester, MN: American Associationof Electrodiagnostic Medicine; 1991. Criteria Met (2/6: 2,6) Source:AAEM Consultant 1993.210. Robinson LR, Micklesen PJ, Wang L. Optimizing the number of testsfor carpal tunnel syndrome. Muscle Nerve 2000;23:1880-1882.Criteria Met (3/6: 3,5,6). Source: Medline Search. Abstract: Thecombined sensory index (CSI), the sum of three latency differences,median-ulnar across the palm (palmdiff), median-ulnar to the ringfinger (ringdiff), and median-radial to the thumb (thumbdiff), hashigher sensitivity and reliability for CTS than individual tests. Theobjective of this study was to develop an approach that minimizestesting but maximizes accuracy. A retrospective study of 300 handsdetermined that there were endpoints for individual tests thatconfidently predicted the results of the CSI; for ranges between theseendpoints, further testing was required. These ranges were: palmdiff0-0.3 ms; ringdiff 0.1-0.4 ms; and thumbdiff 0.2-0.7 ms. Therefore, ifthe results of one of these three tests exceeded these values, it was notnecessary to perform all the NCS necessary to calculate a CSI withoutloss of sensitivity and reliability.211. Robinson LR, Micklesen PJ, Wang L. Strategies for analyzing nerveconduction data: superiority of a summary index over single tests.Muscle Nerve 1998;21:1166-1171. Criteria Met (5/6: 1,2,3,5,6)Source: Medline Search. Abstract: Comparison of three strategies fordiagnosing CTS with NCSs: use of a single NCS result; requirementthat one, two, or three of three NCSs results to be abnormal; and useof a single summary variable incorporating data from three differentNCSs. Sixty-five hands of subjects without clinical CTS werecompared with 66 hands with clinical CTS. Three latency differenceswere measured: median-ulnar (8 cm) midpalmar orthodromic(palmdiff); median-ulnar ring finger (14 cm) antidromic (ringdiff);and median-radial thumb (10 cm) antidromic (thumbdiff). Thecombined sensory index (CSI) was the sum of these three differences.Sensitivity for the tests was palmdiff 69.7%, ringdiff 74.2%,thumbdiff 75.8%, and CSI 83.1%. Specificity was 95.4-96.9%.Requiring one, two, or three of three tests to be abnormal yieldedsensitivities of 84.8%, 74.2%, or 56.1%, respectively, but specificitiesof 92.3%, 98.5%, and 100%, respectively. We conclude that acombined index improves diagnostic classification over use of singletest results.212. Rojviroj S, Sirichativapee W, Kowsuwon W, Wongwiwattananon J,Tammanthong N, Jeeravipoolvarn P. Pressures in the carpal tunnel. Acomparison between patients with carpal tunnel syndrome and normalsubjects. J Bone Joint Surg Br 1990;72:516-518. Criteria Met (3/6:1,3,6) Source: Medline Search.213. Rosecrance JC, Cook TM, Bingham RC. Sensory nerve recoveryfollowing median nerve provocation in carpal tunnel syndrome.Electromyogr Clin Neurophysiol 1997;37:219-229. Criteria Met (6/6:1,2,3,4,5,6) Source: Medline Search. Abstract: The latency andamplitude of orthodromic median SNAP from palm to wrist weremeasured 5 minutes before and at intervals up to 10 minutes untilrecovery after sustained maximal wrist flexion combined with thefingers simultaneously performing finger flexion against resistance.35 hands with a clinical diagnosis of CTS were subdivided into 24with a prolonged baseline latency (+NCS) and 11 with normallatencies (-NCS), and 25 asymptomatic control hands were studied.Four measures were analyzed: difference in latency and amplitudebefore flexion and at 2 minutes afterward, time for the SNAPamplitude to recover to 95% initial value, and time for latency toreturn to initial latency. The latency increased only 1-2% in CTShands compared to controls, but the amplitude decreased to a greaterextent (17%) compared to control hands (2%) and the amplituderecovery time was longer. For groups, mean recovery times were 0.6min controls, 2.25 min CTS (-NCS) group, and, paradoxically, 4.74min for CTS (-NCS) group. Amplitude recovery time greater than1.62 min (asymptomatic mean + 2SD) was considered abnormal forindividual hands. With this criterion, abnormalities were present in 71% of clinically symptomatic hands, including 8 of 11 without otherNCS abnormalities. SNAP recovery time may be complimentary to other NCS to diagnosis CTS but does not replace median orthodromic palm-wrist SNAP latency measurements to diagnose CTS.214. Rosen I. Neurophysiological diagnosis of the carpal tunnel syndrome: evaluation of neurographic techniques. Scand J Plast Reconstr Surg Hand Surg 1993;27:95-101. Criteria Met (4/6: 3,4,5,6) Source:Medline Search. Abstract: Retrospective study of 28 patientsdiagnosed with CTS on basis of combination of clinical, NCS andEMG data. The median motor DML, orthodromic median SNCV forD1 and D3, palmar mixed median NCV were measured and thequotient of SNCV across CT to forearm were calculated in 86 normalcontrols and the results compared to the same studies in the 28 CTSpatients. The palmar mixed median NCV was superior to the quotientof SNCV across CT to forearm and the other tests for the diagnosis ofCTS.215. Rosenberg JN. Anterior interosseous/median nerve latency ratio. ArchPhys Med Rehabil 1990;71:228-230. Criteria Met (4/6: 1,3,5,6)Source: Medline Search. Abstract: With stimulation at the antecubitalfossa and simultaneous recording over the APB and pronatorquadratus (needle electrode) DMLs were determined from 100anterior interosseous nerves in 61 normal volunteers, 5 patients withanterior interosseous syndrome, and 35 patients with CTS. The resultsshow abnormal ratios for both CTS and anterior interosseoussyndrome.216. Rossi S, Giannini F, Passero S, Paradiso C, Battistini N, Cioni R.Sensory neural conduction of median nerve from digits and palmstimulation in carpal tunnel syndrome. Electroencephalogr ClinNeurophysiol 1994;93:330-334.Criteria Met (4/6: 3,4,5,6) Source:Medline Search. Abstract: A variation of palmar stimulation withmore distal stimulation over the metacarpophalangeal interspaces sothat the conduction distances was 1-1.5 cm longer than the usual 8 cmorthodromic palmar conduction study. The more distal stimulationwas performed to evaluate the median nerve palmar branches to theadjacent surfaces of the index and middle finger (P2), the middlefinger and ring finger (P3), and the ulnar palmar branches to theadjacent surfaces of the ring and little finger (P4). The authors notedthat the sensitivity of the modified orthodromic palmar studyparalleled the sensitivity of orthodromic median sensory digitstimulation studies to diagnose CTS. The modified palmar stimulationtechnique had the advantages (1) of frequently demonstrating ameasurable response in CTS patients with stimulation at P3 whereasthe response was absent with stimulation of D4 and (2) ofdemonstrating an abnormality when the response with stimulation atP2 was normal. Since the authors used NCS criteria to select patientsfor the study, the clinical sensitivity and specificity of the modifiedpalmar studies could not be calculated although they could comparethe sensitivity of one study to another.217. Sackett DL, Straus SE, Richardson WS, Rosenberg W, Haynes RB.Evidence-based medicine: how to practice and teach EBM. NewYork: Churchill Livingstone: 2000. Background Reference. Source:AAEM 2000 CTS Task Force member.218. Salerno DF, Franzblau A, Werner RA, Bromberg MB, Armstrong TJ,Albers JW. Median and ulnar nerve conduction studies amongworkers: normative values. Muscle Nerve 1998;21:999-1005. CriteriaMet: (normal population study 4/6: 1,2,5,6) Source: Medline Search:Abstract: To determine normative values for NCS among activeworkers, a prospective cross-sectional study was performed of activeworkers in contrast to the typical reference populations. The authorsselected a subset of 326 workers from 955 subjects who participatedin medical surveys in the workplace. Bilateral median (D2) and ulnar(D5) antidromic sensory conduction studies over a 14 cm conductiondistance to the wrist were performed after checking midpalmtemperature to be 32.0 degrees centigrade or greater with or withoutwarming the limb; limb temperatures were not monitoring during thestudy (personal communication). Median and ulnar SNAP amplitudeand latency (onset and peak) were measured. Workers with upperextremity symptoms, medical conditions that could adversely affectperipheral nerve function, low hand temperature, or highly repetitivejobs were excluded from the “normal” cohort. Linear regressionmodels explained variance in nerve function with covariate of age,sex, hand temperature, and anthropometric factors and provide Practice Parameter: Carpal Tunnel Syndrome Muscle & Nerve Supplement X 2002 S973evidence that electrodiagnostic testing should control for those relevant covariates to improve diagnostic accuracy. The median-ulnarpeak latency difference was the best measure to use if corrections are not made to account for relevant covariates. However, the authors noted the 95th percentile at 0.8 ms in active workers in contrast tocurrent standards of 0.4 to 0.5 ms so that current standards for diagnosing CTS among workers appear too sensitive. 219. Salerno DF, Werner RA, Albers JW, Becker MP, Armstrong TJ,Franzblau A. Reliability of nerve conduction studies among activeworkers. Muscle Nerve 1999;22:1372-1379. Criteria Met (workerpopulation study 4/6: 1,3,5,6). Source: Medline Search. Abstract:Prospective study of the inter-examiner and intra-examiner reliabilityfor the measurement of antidromic median (D2) and ulnar (D5)sensory conduction from wrist with conduction distance of 14 cm andwithout averaging of responses. The first round of testing evaluatedinter-examiner reliability in 158 workers by comparison of the resultsof NCS performed by two different examiners on the same day. Thesecond round of testing was performed 3 weeks later and analyzeddata from 58 subjects retested by examiner 1 and 76 subjects retestedby examiner 2. Midpalm temperature was recorded at the beginningof testing and subjects with cool hands were warmed to 32 degreescentigrade when possible; temperature was not monitoredcontinuously during the testing. The data was analyzed with andwithout correction of latency measurements by 0.3 ms for each degreebelow 35 degrees centigrade. Inter-examiner reliability analysis noted(1) median sensory nerve measurements of amplitude, onset latency,and peak latency were more reliable than ulnar measurements,(2) amplitude and peak latency measurements were more reliable thanonset latency measurements, (3) the median-ulnar peak latencydifference had consistently high reliability, (4) ulnar onset latency hadthe poorest reliability. Inter-examiner reliability analysis showed ahigh congruence between examiners and the same pattern of inter-examiner results between median and ulnar measurements as noted inthe intra-examiner reliability analysis described above. Temperaturecorrection made a small change in reliability of ulnar latencymeasurements. Based on these results, the authors recommended thatthe same examiner perform the repeated NCS in longitudinal studiesto minimize inter-examiner variability and use of median-ulnar peaklatency differences (in addition to short segment orthodromic mediannerve studies) to evaluate patients for CTS.220. Sander HW, Quinto C, Saadeh PB, Chokroverty S. Sensitive median-ulnar motor comparative techniques in carpal tunnel syndrome.Muscle Nerve 1999;22:88-98. Criteria Met (5/6: 1,3,4,5,6) Source:Medline Search. Abstract: CTS was diagnosed in 50 patients (79)hands based on a combination of clinical and electrodiagnosticcriteria (median palm-wrist mixed NAP onset latency greater than 1.7ms or onset latency exceed the ipsilateral ulnar palm-wrist latency bymore than 0.3 ms as described by Jackson and Clifford in 1988).Three motor conduction studies were evaluated: the median-thenar toulnar-thenar latency difference (TTLD), the medianthenar to ulnar-hypothenar latency difference (THLD), and the ulnar-to-median F-wave latency difference (FWLD). The abnormal cutoffs based upon34 normal controls are: TTLD, 0.8 ms; THLD, 1.2 ms; FWLD, 0.6ms. The diagnostic sensitivities were: 95-98%, 85-88%, and 75-78%,respectively, in this CTS patient group with abnormal median sensoryconduction studies as described above.221. Scelsa SN, Herskovitz S, Bieri P, Berger AR. Median mixed andsensory nerve conduction studies in carpal tunnel syndrome.Electroencephalogr Clin Neurophysiol 1998;109:268-273. CriteriaMet (6/6: 1,2,3,4,5,6) Source: Medline Search. Abstract: To assess thesensitivities and specificities of velocity differences between medianmixed nerve conduction across the wrist (Medmxpw) and (I) medianmixed nerve conduction in the forearm (Medmxf) and (II) palm to D2sensory conduction (MedpD2), we prospectively studied 67 limbs ofpatients with clinically definite carpal tunnel syndrome (CTS).Medmxf and Medmxpw were performed by stimulating the mediannerve at the elbow and palm respectively and recording at theproximal wrist crease. We also compared conventional mediansensory (D2-wrist) and mixed (palm-wrist) tests in all patients. Thirtylimbs of asymptomatic subjects served as normal controls and 21limbs of subjects with other neuropathies served as diseased controls;control data was collected prospectively. The sensitivity of theMedpD2-Medmxpw difference (0.87) was significantly greater thanthat of the Medmxf-Medmxpw difference (0.61, P <0.001). Both tests were similar and highly specific (0.98 and 0.96, respectively). TheMedpD2-Medmxpw study is among the most sensitive and specific electrophysiologic tests for CTS. 222. Schwartz MS, Gordon JA, Swash M. Slowed nerve conduction withwrist flexion in carpal tunnel syndrome. Ann Neurol 1980;8:69-71. Criteria Met (3/6: 1,2,5) Source: Golding, 1986. Abstract: DMLs from the wrist to APB and DSLs from the index finger to the wristwere determined in 32 hands in 20 patients and 10 control subjects.The latencies were determined before and after 2 minutes of fullvoluntary wrist flexion (Phalen’s maneuver). They found that theDSL or DML increased by greater than 0.2 ms in 16 out of 32 CTSpatients and was not greater than 0.1 ms in normal subjects. In 2 CTSpatients the only abnormality was the increase in distal latencies afterPhalen’s maneuver. Temperature differences before and after wristflexion were not reported.223. Sener HO, Tascilar NF, Balaban H, Selcuki D. Sympathetic skinresponse in carpal tunnel syndrome. Clin Neurophys 2000;111:1395-1199. Criteria Met (6/6: 1,2,3,4,5,6) Source: Medline Search.Abstract: Prospective study of 31 CTS patients and 21 healthyvolunteers of the sympathetic skin response (SSR) recorded from D2and D5 with sternal stimulation. Sternal stimulation was chosen toelicit the SSR instead of limb stimulation to avoid the effect ofafferent dysfunction in a limb on the results. The SSR latencyrecorded from symptomatic limbs of CTS did not differ from normalcontrols, and the same was true for median-to-ulnar ratios of latency,amplitude and area of the SSR. Of a subset of 23 CTS patients whocompleted a questionnaire, 70% of CTS patients did complain ofsympathetic symptoms in the symptomatic limbs: red or purplediscoloration, excessive sweating, or feeling cold (personalcommunication).224. Seror P. Comparative diagnostic sensitivities of orthodromic orantidromic sensory inching test in mild carpal tunnel syndrome. ArchPhys Med Rehabil 2000; 81:442-446. Criteria Met (4/6: 1,3,5,6)Source: Medline Search. Abstract: Prospective study comparing theorthodromic inching test (OIT) to the antidromic inching test (AIT) inthe dominant hand of 20 CTS patients with control data from 20normal subjects. The diagnosis of the 20 CTS patients was based onclinical criteria and confirmed by NCS. To select cases of definite butmild CTS, the criteria for NCS results was as follows: normal medianmotor distal latency (<4.0 ms), normal sensory conduction velocitypalm-wrist (>45 m/s), and abnormal median-ulnar latency differenceof the fourth digit (>0.4ms). Temperature was measured at the start ofthe study, but not monitored continuously during the study. The IT(100% positive) was superior to the AIT (20% positive) in the 20 CTSpatients.225. *Seror P. Comparison of the distal motor latency of the first dorsalinterosseous with abductor pollices brevis. Report of 200 cases.Electromyogr Clin Neurophysiol 1988;28:341-345. Criteria Met (1/6:1) Source: Medline Search.226. Seror P. Orthodromic inching test in mild carpal tunnel syndrome.Muscle Nerve 1998a;21:1206-1208. Criteria Met (4/6: 2,3,5,6).Source: Medline Search. Abstract: Orthodromic inching test (OIT) ofthe median nerve at wrist was performed on the dominant wrist of 80controls and 100 patients with mild CTS defined by the presence ofclinical features and chosen for study because standardelectrodiagnostic tests for CTS were normal (median motor distallatency less than 4 ms and palm-to-wrist orthodromic sensoryconduction velocity greater than 45 m/s). In controls the meanconduction delay per centimeter (CD/cm) was 0.184 ms and wasslightly higher inside than outside the carpal tunnel; the maximalCD/cm (MCD/cm) was never greater than 0.34 ms (mean 0.247). TheMCD/cm was 0.36 ms or more in 96 CTS patients. This abnormalitywas located within the carpal tunnel in 92% of cases. Outside theentrapment site CD/cm values remained normal and similar to thosefound in the controls. On the whole, this results in an overallspecificity of 100% and sensitivity of 96% for the OIT.227. Seror P. Phalen’s test in the diagnosis of carpal tunnel syndrome. JHand Surg 1988;13-B:383-385. Criteria Met (3/6: 1,2,6) Source:Medline Search.228. Seror P. Sensitivity of the various tests for the diagnosis of carpaltunnel syndrome. J Hand Surg [Br ] 1994;19:725-728. Criteria Met(5/6: 1,3,4,5,6) Source: Medline Search. Abstract: A prospective Practice Parameter: Carpal Tunnel Syndrome S974 CTS Literature Review© 2002 American Association of Electrodiagnostic Medicinestudy of 150 hands in 96 patients suspected of CTS. Patients were included in the study because at least one EDX test for CTS wasabnormal; patients suspected of CTS with normal EDX tests were excluded from the analysis. The data was used to compare the relative sensitivity of nine different EDX tests to diagnose CTS. The distalmotor latency was greater than 5 ms in 35% of cases and greater than or equal to 4 ms in 55% of cases. The D3 to wrist (14 cm) orthodromic median sensory CV was less than or equal to 45 m/s in66% of cases. The palm to wrist (8 cm) orthodromic median CV wasless than or equal 45 m/s in 76%. The remaining 24% of cases wereassessed by additional EDX tests: the median-ulnar latency differencerecorded from D4 was abnormal in 21 of the remaining 24% and thecentimetric test was altered in all 24%. The median-ulnar latencydifference is simpler to perform than the centimetric test and, in thisstudy, there was only a small difference in the percentage of mediannerve abnormalities detected in CTS suspects with these two tests.229. Seror P. The axonal carpal tunnel syndrome. Electroencephalogr ClinNeurophysiol 1996b;101:197-200. Criteria Met (4/6: 1,4,5,6) Source:Medline Search. Abstract: Five patients with clinical symptoms ofCTS and a response to a single corticosteroid injection of the CT werestudied. Each patient had a normal electrodiagnostic evaluation,including needle examination (C5 to C8T1), distal motor latency,palm to wrist orthodromic sensory conduction velocity, and specialtests: median-ulnar latency difference of the 4th digit, palmarcentimetric technique. A new test is described: the orthodromicsensory ultra distal stimulation of each digit “at the pulp” withrecording over the median nerve at the wrist for digits 1,2,3,4 andover the ulnar nerve for digit 5. The test revealed a significantamplitude change (60-90%) in at least two median digits of thesymptomatic hand compared to the asymptomatic hand interpreted as“axonal loss” in these five CTS patients. These findings led to theproposal of the term “axonal CTS.”230. Seror P. Tinel’s sign in the diagnosis of carpal tunnel syndrome. JHand Surg 1987;12-B:364-365. Criteria Met (3/6: 1,2,6) Source:Medline Search.231. Shafshak TS, el-Hinawy YM. The anterior interosseous nerve latencyin the diagnosis of severe carpal tunnel syndrome with unobtainablemedian nerve distal conduction. Arch Phys Med Rehabil 1995; 76:471-475. Criteria Met (5/6: 1,3,4,5,6). Source: Medline Search.Abstract: The authors concluded that measurement of the anteriorinterosseous nerve latency (AINL) with surface electrodes has a rolein the differential diagnosis of severe CTS from other causes ofmedian nerve pathology. The alternative is to perform needle EMGexamination of forearm muscles innervated by the median nerve.232. Shahani BT, Young RR, Potts F, Maccabee P. Terminal latency index(TLI) and late response studies in motor neuron disease (MND),peripheral neuropathies and entrapment syndromes. Acta NeurolScand 1979;73(suppl):118. Criteria Met (0/6) (Abstract only) Source:Stevens, 1987.233. Sheean GL, Houser MK, Murray NM. Lumbrical-interosseous latencycomparison in the diagnosis of carpal tunnel syndrome.Electroencephalogr Clin Neurophysiol 1995;97:285-289. Criteria Met(4/6: 1,3,5,6) Source: Medline Search. Abstract: In 66 hands of 45patients with suspected CTS, the second lumbrical-interosseous distalmotor latency difference (2LI-DML) was abnormal as frequently (48hands, 72%) as the median-ulnar orthodromic mixed nerve palmarvelocity difference.234. *Shurr DG, Blair WF, Bassett G. Electromyographic changes aftercarpal tunnel release. J Hand Surg Am 1986;11:876-880. Criteria Met(2/6: 1,2) Source: Medline Search.235. *Silverstein B, Fine L, Stetson D. Hand-wrist disorders amonginvestment casting plant workers. J Hand Surg Am 1987;12:838-844.Criteria Met (0/6) Source: Medline Search.236. Simovic D, Weinberg DH. Terminal latency index in the carpal tunnelsyndrome. Muscle Nerve 1997a;20:1178-1180. Criteria Met (3/6:3,4,5) Source: Medline Search. Abstract: A retrospective studyevaluated the usefulness of the median motor terminal latency index(m-TLI) to diagnose CTS. The m-TLI is a derived measure of distalmotor conduction and calculated as follows: terminal distance /(proximal conduction velocity × distal latency). The 132 hands of 107patients suspected of CTS were divided into two groups based on theresults of mixed nerve palmar stimulation studies (normal ≤2.2 ms ormedian to ulnar peak latency difference ≤0.4 ms.) Group I containedpatients with abnormal median palmar peak latencies (likely to have CTS). while group 2 contains patients with normal median palmarpeak latencies (less likely to have CTS). The m-TLI was less than 0.34 in all patients in Group 1 and equal or greater than 0.34 in all patients in Group 2. This retrospective study suggests that the m-TLIis a diagnostic test for CTS potentially as useful as the median palmar conduction study (see 1999b reference). 237. Simovic D, Weinberg DH. The median nerve terminal latency indexin carpal tunnel syndrome: a clinical case selection study. MuscleNerve 1999b;22:573-577. Criteria Met: (6/6: 1,2,3,4,5,6) Source:Medline Search. Abstract: The median terminal latency index (TLI) isa calculated value derived from the conventional median motor NCSdata. The TLI is a ratio that adjusts the median motor distal latency(DL) for the terminal conduction distance (CD) and the proximalnerve conduction velocity (CV): TLI = terminal CD (mm) /[proximalCV (m/s) × DL (ms)]. The ratio decreases as the conduction timeincreases across the carpal tunnel. In this prospective study of 66patients to assess the sensitivity of the median nerve TLI for thediagnosis of carpal tunnel syndrome (CTS), clinical andelectrophysiological evaluations were completed by separate, blindedexaminers. Based on clinical diagnostic criteria, 54 of the 66 patients(54 hands) were determined to have CTS (CTS group). Control datawere obtained from 19 healthy subjects (38 hands). The mean TLIwas 0.26 ± 0.04 in the CTS group and 0.43 ±0.04 in the control group(P <0.001). The sensitivity of the TLI for the diagnosis of CTS was81.5%. The TLI was more sensitive to diagnose CTS than the medianmotor DL and median sensory peak latency (PL) to the second digit(CD 14 cm). The TLI was always abnormal when the median mixed-nerve palmar latency was abnormal. In three cases from the CTSgroup, the TLI was the only abnormal electrophysiological parameter.238. Simpson JA. Electrical signs in the diagnosis of carpal tunnel andrelated syndromes. J Neurol Neurosurg Psychiatry 1956;19:275-280.Criteria Met (2/6: 3,5) Source: Palliyath, 1990.239. Smith T. Near-nerve versus surface electrode recordings of sensorynerve conduction in patients with carpal tunnel syndrome. ActaNeurol Scand 1998; 98: 280-282. Criteria Met (5/6: 1,3,4,5,6) Source:Medline Search. Abstract: Comparison of the relative sensitivity ofsensory nerve conduction (SNC) recorded with near-nerve needleelectrodes and SNC recorded with surface electrodes to demonstratefocal slowing of the median nerve conduction in CTS patients. 82consecutive patients with clinical symptoms and signs of CTS werestudied prospectively by the same clinical neurophysiologist.Orthodromic near-nerve recording from digits 1 and 3, distal medianmotor latency, and antidromic surface recording from palm to digit 2and wrist to digit 2 were performed in all patients. Near-nerverecording of the ulnar nerve was done in patients with abnormalmedian nerve conduction. Near-nerve SNC was abnormal comparedto control (slowed velocity or absent response) in 52% of the patientsfrom digit 1 to wrist, in 51% from digit 3 to wrist, and 40% had aprolonged distal motor latency. Surface antidromic SNC wasabnormal in 49% from wrist to palm, and in 43% from wrist to digit2. Statistical analysis revealed no significant difference between thenear-nerve method and the surface method.240. So YT, Olney RK, Aminoff MJ. Evaluation of thermography in thediagnosis of selected entrapment neuropathies (comments inNeurology 1989;39:1003-1005). Neurology 1989;39:1-5. Criteria Met(2/6: 1,2) Source: Medline Search.241. *Spindler HA, Dellon AL. Nerve conduction studies and sensibilitytesting in carpal tunnel syndrome. J Hand Surg 1982;7:260-263.Criteria Met (3/6: 2,3,5) Source: Jordan, 1987.242. Stetson DS, Albers JW, Silverstein BA,Wolfe RA. Effects of age, sex,and anthropometric factors on nerve conduction measures. MuscleNerve 1992;15:1095-1104. (normal population study 5/6: 1,3,4,5,6)Source: Buschbacher 1999. Study of 105 healthy, asymptomaticadults without history of hand-intensive occupational activities.Height and finger circumference was negatively associated withsensory amplitude of median, ulnar and sural nerves. Height waspositively associated with median, ulnar and sural sensory distallatencies. Equations using age, height and finger circumference forprediction of normal values are presented. Failure to adjust normalnerve conduction values for these factors decreases the diagnosticspecificity and sensitivity of nerve conduction studies.243. Stevens JC. AAEE Minimonograph #26: The electrodiagnosis of Practice Parameter: Carpal Tunnel Syndrome Muscle & Nerve Supplement X 2002 S975carpal tunnel syndrome. Muscle Nerve 1987;10:99-113. Criteria Met (3/6: 3,5,6) Source: Medline Search. Abstract: The author presents (1)the electrodiagnostic findings in 505 cases of CTS evaluated at the Mayo Clinic from 1961-1980, (2) normal values for median and ulnar sensory and motor conduction, (3) an EDX protocol for evaluation ofCTS, and (4) a protocol to identify Martin-Gruber anastomosis. 244. Stevens JC, Smith BE, Weaver AL, Bosch EP, Deen HG Jr, Wilkens JA. Symptoms of 100 patients with electromyographically verifiedcarpal tunnel syndrome. Muscle Nerve 1999;22:1448-1456.Background Reference. Source: Medline Search. Abstract: Todetermine the symptoms of carpal tunnel syndrome (CTS), screeningevaluations were performed in 244 consecutive patients with sensorysymptoms in the hand and unequivocal slowing of median nerveconduction at the wrist. This yielded 100 patients thought to have noexplanation other than CTS for their upper limb complaints. Thesepatients completed a hand symptom diagram (HSD) and questionnaire(HSQ) about their symptoms. CTS symptoms were most commonlyreported in median and ulnar digits, followed by median digits onlyand a glove distribution. Unusual sensory patterns were reported bysome patients. Based on the HSQ, paresthesias or pain proximal to thewrist occurred in 36.5% of hands. The usefulness of the HSD andHSQ for diagnosis was determined by asking three physicians,blinded to the diagnosis, to rate the likelihood of CTS in the patientswith CTS and in 50 patients with other causes of upper extremityparesthesia. The sensitivities of the independent instruments rangedfrom 54.1% to 85.5%. Based on the combined instrument ratings, thesensitivity increased to 79.3% to 93.7%.245. Stevens JC, Sun S, Beard CM, O’Fallon WM, Kurland LT. Carpaltunnel syndrome in Rochester, Minnesota, 1961-1980. Neurology1988;38:134-138. Background Reference. Source: Medline Search.246. Steward JD, Eisen A. Tinel’s sign and the carpal tunnel syndrome. BrMed J 1978;2:1125-1126. Criteria Met (1/6: 3) Source: Golding,1986.247. Szabo RM, Gelberman RH, Dimick MP. Sensibility testing in patientswith carpal tunnel syndrome. J Bone Joint Surg 1984;66A:60-64.Criteria Met (1/6: 1) Source: Borg, 1988.248. Tackmann W, Kaeser HE, Magun HG. Comparison of orthodromicand antidromic sensory nerve conduction velocity measurement in thecarpal tunnel syndrome. J Neurol 1981;224:257-266. Criteria Met(6/6: 1,2,3,4,5,6) Source: Uncini, 1989. Abstract: Using ringelectrodes on the middle finger and subdermal electrodes at themidpalm and wrist, orthodromic and antidromic SNAP latencies wererecorded from 56 hands from 50 CTS patients and 32 hands from 32healthy subjects. They report no significant differences in latencies oforthodromic and antidromic recordings and that palmar latencies aremore likely to be abnormal in CTS than digit latencies.249. Tackmann W, Lehman HJ. Relative refractory period of median nervesensory fibers in the carpal tunnel syndrome. Eur Neurol1974;12:309-316. Criteria Met (4/6: 1,2,4,5) Source: Palliyath, 1990.Abstract: With stimulation on the index finger and recording at thewrist, the relative median nerve refractory period was determinedwith paired stimuli in 11 hands of eight CTS patients and 12 hands ofeight healthy controls. They found the relative refractory period morelikely to be prolonged in patients with CTS as opposed to normalsubjects.250. *Terzis S, Paschalis C, Metallinos IC, Papapetropoulos T. Earlydiagnosis of carpal tunnel syndrome: comparison of sensoryconduction studies of four fingers. Muscle Nerve 1998; 21: 1543-1545. Criteria Met (3/6: 3,5,6) Source: Medline Search. Abstract:Sensory studies of four fingers were performed on 72 patients withearly (distal motor latency <4.2 ms) carpal tunnel syndrome (CTS)and on 43 control subjects. Results demonstrate that sensory studiesof digit 4 yields the highest sensitivity (88%) for diagnosis of earlyCTS. The sensitivity of digit 1, digit 2, and digit 3 was 61%, 22%,and 50%, respectively.251. Thomas JE, Lambert EH, Cseuz KA. Electrodiagnostic aspects of thecarpal tunnel syndrome. Arch Neurol 1967;16:635-641. Criteria Met(3/6: 3,5,6) Source: Nau, 1988.252. Thomas PK. Motor nerve conduction in carpal tunnel syndrome.Neurology 1960;10:1045-1050. Criteria Met (5/6: 1,2,3,5,6) Source:Wiederholt, 1970. Abstract: With coaxial needle recording over theAPB, stimulation at the wrist, elbow, and axilla, CMAPs and DMLswere recorded over the APB in 95 CTS patients and 50 controlsubjects. The DML was prolonged in approximately two-thirds of the CTS patients.253. Trojaborg W, Grewal RP, Weimer LH, Sheriff P. Value of latency measurements to the small palm muscles compared to other conduction parameters in the carpal tunnel syndrome. Muscle Nerve1996;19:243-245. Criteria Met (5/6: 1,2,3,5,6). Source: Medline Search. Abstract: Study of 170 hands of 105 patients with clinical diagnosis of CTS. There was an abnormal lumbrical-interosseuslatency difference in 83% of hands whereas there was an abnormalmedian sensory conduction velocity from the thumb to the wrist in93% of hands. The authors concluded that the lumbrical-interosseuslatency difference was especially useful in confirming CTS in patientswith absence of the median SNAP or APB motor response or both.254. Uncini A, Di Muzio A, Awad J, Manente G, Tafuro M, Gambi D.Sensitivity of three median-to-ulnar comparative tests in diagnosis ofmild carpal tunnel syndrome [see comments]. Muscle Nerve1993;16:1366-1373. Criteria Met (6/6: 1,2,3,4,5,6). Source: MedlineSearch. Abstract: Study of 193 hands of 113 patients with clinicaldiagnosis of CTS compared to reference population of 72 hands of 47volunteers. Ninety-five (49%) hands had normal median DML (≤4.2ms) and normal or borderline median SNCV from digit 2 stimulation(≥45 m/s). In this subpopulation of 95 hands, the authors performedthree median to ulnar comparative tests: (1) difference betweenmedian and ulnar distal motor latencies recorded from the secondlumbrical and interossei muscles (2L-INT); (2) difference betweenmedian and ulnar sensory latencies from digit 4 stimulation (D4M-D4U); and (3) difference between median and ulnar mixed nervelatencies from palmar stimulation (PM-PU). The 2L-INT differencewas greater than or equal to 0.6 ms in 10 (10%) of the subpopulationof 95 hands. PM-PU and D4M-D4U were greater than or equal to 0.5ms in 53 (56%) and 73 (77%) of the subpopulation of 95 hands,respectively. If each of these three studies were abnormal in the 98hands with abnormal median DML or median D2S, the maximumsensitivity for the three tests would be (10 + 98 = 108)/193 = 56%,(53 + 98 = 151)/193 = 78%, and (73 + 98 = 171)/193 = 89%. Thecomparison of median and ulnar sensory conduction across the CTwas more sensitive than comparison of median and ulnar motorconduction across the CT. The sensitivity of D4M-D4U might beexplained by the funicular topography and consequent greatersusceptibility to compression of the cutaneous fibers from the thirdinterspace which, at the distal carpal tunnel, are clumped superficiallyin the volar-ulnar portion of the median nerve just beneath thetransverse ligament.255. Uncini A, Lange DJ, Solomon M, Soliven B, Meer J, Lovelace RE.Ring finger testing in carpal tunnel syndrome: A comparative study ofdiagnostic utility (comments in Muscle Nerve 1990;13:560). MuscleNerve 1989;12:735-741. Criteria Met (4/6: 1,2,3,5) Source: MedlineSearch. Abstract: With stimulation at the wrist and recording over thering finger, the median and ulnar DSL latency differences wererecorded in 43 hands of 33 normals and 42 hands in 32 patients withmild CTS as defined by electrodiagnostic criteria. Standard DMLfrom wrist to APB, and median DSL from wrist to index finger werealso determined. They found that the median ulnar difference to thering finger was more likely to be abnormal than the DML and DSL.256. *Valls J, Llanas JM. Orthodromic study of the sensory fibersinnervating the fourth finger. Muscle Nerve 1988;11:546-552.Criteria Met (3/6: 1,3,5) Source: Medline Search.257. Valls-Sole J, Alvarez R, Nunez M. Limited longitudinal sliding of themedian nerve in patients with carpal tunnel syndrome. Muscle Nerve1995; 18: 761-767. Criteria Met (4/6: 1,3,5,6) Source: MedlineSearch. Abstract: During normal movements or changes in position ofthe limbs, nerve structures must accommodate the resulting changesin length of the nerve path. In patients with CTS, we monitoredelectrophysiologically the longitudinal adjustment of the mediannerve to positions of extreme flexion and extreme extension of thewrist and elbow, by measuring the differences induced in the latencyof the SNAP recorded in the forearm and upper arm. In patients, thelatency difference was significantly shorter than in normal subjects(0.196 ± 0.084 ms vs. 0.088 ± 0.059 ms in the forearm, and 0.485 ±0.122 ms vs. 0.129 ± 0.086 ms in the upper arm). These resultsindicate that the displacement of the source of the median nerveSNAP with movements of flexion and extension is limited in patientswith carpal tunnel syndrome. Since the latency changes in CTS Practice Parameter: Carpal Tunnel Syndrome S976 CTS Literature Review© 2002 American Association of Electrodiagnostic Medicinepatients were less than but within the range of latency changes in normal controls, the procedure cannot be used to distinguish CTSpatients from controls. However, the abnormality noted may be a manifestation of the pathophysiology of entrapment syndromes: limited longitudinal sliding of nerves in entrapment neuropathies.258. Vennix MJ, Hirsh DD, Chiou-Tan FY, Rossi CD. Predicting acute denervation in carpal tunnel syndrome. Arch Phys Med Rehabil 1998;79:306-312. Criteria Met (3/6: 3,4,6) Source: Medline Search.Abstract: Retrospective study of 1590 patients diagnosed with medianneuropathy at the wrist based on the results of NCS alone todetermine the relationship of evidence of acute denervation on needleEMG of the APB to patient age, gender, and NCS parametersincluding median sensory peak latency and amplitude, and medianmotor distal latency and amplitude. Logistic regression analysisidentified gender, median motor distal latency, and median motoramplitude (all p ≤.008) as contributing to the prediction ofdenervation. Needle EMG of the cases with a median CMAPamplitude <7 mV detected 95.3% (141/148) of all cases withdenervation. However, the model is not applicable for predicting thepresence of denervation in the individual patient.259. Verghese J, Galanopoulou AS, Herskovitz S. Autonomic dysfunctionin idiopathic carpal tunnel syndrome. Muscle Nerve 2000;23:1209-1213. Criteria Met (5/6 1,3,4,5,6) Source: AAEM CTS Task Force2000 member. Abstract: A prospective study of autonomicdisturbances in 139 limbs of 76 CTS patients diagnosed on the basisof clinical and sensory and motor NCS abnormalities. Autonomicdisturbances were identified as follows: swelling of the fingers (39%),dry palms (33%), Raynaud’s phenomenon (32%) and blanching of thehand (32%), finger tip ulcerations (0%) and nail changes (0%). Coldsensation of the fingertips (too non-specific) and excessive sweating(not reported in a preliminary survey) were not included. SympatheticSkin Response (SSR) abnormalities (latency >1.72 ms or absentresponse) were noted in 24% (33 of 139) symptomatic hands andwere more common in hands with autonomic symptoms (34%; 26 of76 hands). Compared to control patients, the SSR had a specificity of89%.260. Wang AK, Raynor EM, Blum AS, Rutkove SB. Heat sensitivity ofsensory fibers in carpal tunnel syndrome [see comments]. MuscleNerve 1999;22:37-42. Criteria Met (5/6: 1,3,4,5,6) Source: MedlineSearch. Abstract: CTS used as a model to study the effect of heat onnerves with focal demyelination secondary to chronic compression.Median SNAP amplitude and area decreased more in 12 CTS patientsthan in 12 normal controls at 42 degree C compared to baselinemeasurements at 32 degrees centigrade. It is hypothesized that thesereductions in response amplitude are secondary to the occurrence ofheat-induced conduction block in demyelinated sensory neurons.261. Werner RA, Albers JW. Relation between needle electromyographyand nerve conduction studies in patients with carpal tunnel syndrome.Arch Phys Med Rehabil 1995;76:246-249. Criteria Met (2/6: 3,6)Source: Medline Search. Abstract: Retrospective study of 480 casesof electrodiagnostically confirmed CTS reviewed to determine if thefindings on NCS could predict the presence or absence of fibrillationpotentials or motor unit changes on the needle EMG of the APB. Twohundred thirty-one CTS patients had an abnormal needle EMG examdefined by presence of fibrillation activity (105 patients) and/orabnormal MUAP configuration. Motor and sensory evoked potentiallatencies were the most important predictors of an abnormal needleEMG examination.262. Werner RA, Bir C, Armstrong TJ. Reverse Phalen’s maneuver as anaid in diagnosing carpal tunnel syndrome. Arch Phys Med Rehabil1994;75:783-786. Criteria Met (6/6, 1,2,3,4,5,6) Source: MedlineSearch. Abstract: Direct intracarpal canal pressure measurements in 5subjects demonstrated that a reverse Phalen’s maneuver (wrist andfinger extension) results in a significantly higher intracarpal canalhydrostatic pressure compared to a traditional Phalen’s (wrist flexionand finger extension) or a modified Phalen’s maneuver (wrist flexionwhile pinching a flat object between the thumb and third digit). 31individuals with a clinical diagnosis of carpal tunnel syndrome and 20normal controls were evaluated to determine the effect the reversePhalen’s maneuver would have on antidromic median sensory latencyand amplitude measured with the wrist and hand in the neutralposition. Both groups demonstrated slight (1-4%) prolongation of thepeak latency and reduction in the amplitude of the median SNAP after1 minute of this maneuver. The control group had a mean peak latency prolongation of 0.05 ms (1.6% of the mean) and a meanamplitude reduction of 1.5 microvolts (2.6% of the mean) compared to 0.13 ms (3% of the mean) and 0.9 microvolts (4% of the mean) in the carpal tunnel syndrome group. Only the change in peak latencymeasurements between the two groups was significant at a p = 0.05 level. Additional studies with longer periods of maintained wrist extension were recommended to evaluate this technique to diagnoseCTS.263. Werner RA, Franzblau A, Albers JW, Armstrong TJ. Medianmononeuropathy among active workers: are there differences betweensymptomatic and asymptomatic workers? Am J Ind Med1998;33:374-378. Criteria Met: (worker population study 3/6: 1,3,6).Source: Medline Search. Abstract: A prospective cross-sectionalstudy of 700 active workers identified 184 with median neuropathdefined as a prolongation of the median SNAP peak latency comparedto the ulnar SNAP peak latency by at least 0.5 ms, antidromic studies,conduction distances 14 cm each to D2 and D5. Cool hands werewarmed before testing but temperature was not monitored in everycase during the testing. A review of self-reported symptoms of pain,numbness, tingling and burning in the hands or fingers lasting morethan 1 week or occurred 3 or more times at the of the screening wasused to identify “symptomatic” workers. Workers who complained ofsymptoms were more likely to be female, to have jobs with higherhand repetition levels, to have higher ratings of job security, not tohave a history of diabetes, to use more force in their job with moreabnormal postures of their wrist and fingers, and to have a trendtoward a more prolonged median sensory distal latency. As noted bythe authors, the study is limited because it is cross-sectional andcannot answer many of the questions raised: a longitudinal studywould be necessary to determine the incidence and natural history ofmedian mononeuropathy among active workers.264. White JC, Hansen SR, Johnson RK. A comparison of EMGprocedures in the carpal tunnel syndrome with clinical-EMGcorrelations. Muscle Nerve 1988;11:1177-1182. Criteria Met (3/6:1,2,3) Source: Medline Search. Abstract: Two hundred one hands in122 patients were evaluated with several techniques for CTS. Theasymptomatic hands of 43 of these patients served as controls. Thefollowing techniques were evaluated: (a) DML from wrist to APB, (b)DSL from wrist to index finger, (c) motor inching studies across thewrist to APB, (d) sensory inching studies across the wrist to the indexfinger, (e) inching studies to the lumbrical, (f) palm-to-wrist medianlatency, (g) comparison of median and radial DSLs, and (h) terminallatency index. Motor inching studies were most likely to be abnormalin both the CTS group and asymptomatic group. Motor inchingstudies were abnormal in 92% of mild CTS hands and 72% of theasymptomatic hands. All of the studies had high rates of abnormalityin asymptomatic hands varying from 9% to 72%. 265. Wiederholt WC. Median nerve conduction velocity in sensory fibersthrough carpal tunnel. Arch Phys Med Rehabil 1970;51:328-330.Criteria Met (normal population study 5/6: 1,3,4,5,6) Source:Macleod, 1987. Abstract: With stimulation over the middle finger andrecording distal and proximal to the carpal tunnel, sensory NCVswere determined across the carpal tunnel and proximal to the carpaltunnel in 30 normal adults. Sensory NCV was faster proximal to thecarpal tunnel than across the carpal tunnel. No CTS patients werestudied.266. Wilbourn AJ: Electrodiagnosis of plexopathies. In: Aminoff MJ,editor. Neurologic clinics: symposium on electrodiagnosis. Vol 3, No3:511-529. Philadelphia: WB Saunders; 1985. pp. 512-516. CriteriaMet: Background Source: AAEM Consultant 1993.267. Wilbourn AJ, Lambert EH. The forearm median-to-ulnar nervecommunication; electrodiagnostic aspects (abstract). Neurology1976:26:368. Background Source: AAEM Consultant 1993.268. Wilson JR. Median mixed nerve conduction studies in the forearm:evidence against retrograde demyelination in carpal tunnel syndrome.J Clin Neurophysiol 1998;15:541-546. Background Reference.Source: Medline Search. Abstract: Motor conduction velocity (CV)measurements sometimes show conduction velocity slowing in theforearm segment of the median nerve in carpal tunnel syndrome(CTS). This slowing of motor nerve conduction is thought to becaused by either retrograde demyelination in the forearm or Practice Parameter: Carpal Tunnel Syndrome Muscle & Nerve Supplement X 2002 S977conduction block of the fastest fibers within the carpal tunnel. Direct measurement of the forearm segment of the median nerve were madeto distinguish between these two possibilities. Median motor conduction studies and mixed nerve action potential (MNAP) recordings were performed on the forearm segment of the mediannerve in patients (n = 32 limbs, aged 24 to 76) and controls (n = 15 limbs, aged 33 to 76). The results strongly support the hypothesis that the slowing seen in the forearm is caused by conduction block of thefastest conducting fibers within the carpal tunnel and is not caused byretrograde demyelination.269. *Winn FJ Jr, Krieg EF Jr. A regression model for carpal tunnelsyndrome. Proc Soc Exp Biol Med 1989;192:161-165. Criteria Met(2/6: 1,2) Source: Medline Search.270. Woltman HW. Neuritis associated with acromegaly. Arch NeurolPsychiatry 1941;45:680-682. Background Reference. Source:Gelbermann, 1980.271. Wongsam PE, Johnson EW, Weinerman JD. Carpal tunnel syndrome:use of palmar stimulation of sensory fibers. Arch Phys Med Rehabil1983;64:16-19. Criteria Met (3/6: 3,5,6) Source: Pease, 1989.Abstract: With stimulation at the wrist and midpalm and recordingwith ring electrodes over the middle finger, DSLs were obtained fromthe median nerve and 100 hands from 50 normal subjects, 15 patientswith early CTS, and 6 with diabetes mellitus and superimposedmedian nerve entrapment. Amplitudes and durations of the SNAP were also reported. This technique is reported as useful in thediagnosis of CTS and underlying mild peripheral neuropathy. 272. You H, Simmons Z, Freivalds A, Kothari MJ, Naidu SH. Relationships between clinical symptom severity scales and nerveconduction measures in carpal tunnel syndrome. Muscle Nerve 1999;22:497-501. Criteria Met (5/6: 1,3,4,5,6). Source: Medline Search. Background Reference. Abstract: This study examined theseverity of symptoms in carpal tunnel syndrome (CTS) in relation tonerve conduction measures of the median nerve. Significantrelationships identified among the clinical scales resulted in adichotomous symptom classification scheme into primary symptomsmore specific for nerve injury (numbness, tingling, nocturnalsymptoms) and secondary symptoms (pain, weakness, clumsiness).There were significant relationships between symptom severity andnerve conduction abnormality, and the primary symptom scalecorrelated more strongly with the electrodiagnostic measures of nerveinjury than did the secondary symptom scale.273. Zachary RB. Thenar palsy due to compression of the median nerve inthe carpal tunnel. Surg Gynecol Obstet 1945;81:213-217. BackgroundReference. Source: Gelbermann, 1980. Practice Parameter: Carpal Tunnel Syndrome S978 CTS Literature Review© 2002 American Association of Electrodiagnostic Medicine