Sensitivities of conventional and new electrophysiological techniques in carpal tunnel syndrome and their relationship to body mass index^[*]

Abstract

The purpose of this study is to evaluate prospectively the sensitivities of conventional and new electrophysiological techniques and to investigate their relationship with the body mass index (BMI) in a population of patients suspected of having carpal tunnel syndrome (CTS).

In this study, 165 hands of 92 consecutive patients (81 female, 11 male) with clinical diagnosis of CTS were compared to reference population of 60 hands of 30 healthy subjects (26 female and 4 male). Extensive sensory and motor nerve conduction studies (NCSs) were performed in the diagnosis of subtle CTS patients. Also, the patients were divided into subgroups and sensitivities were determined according to BMI.

The mean BMI was found to be significantly higher in the CTS than in the control group (p < 0.001). The sensitivity of the median sensory nerve latency (mSDL) and median motor distal latency (mMDL) were 75.8% and 68.5%, respectively. The most sensitive parameters of sensory and motor NCSs were the difference between median and ulnar sensory distal latencies to the fourth digit [(D4M-D4U), (77%)] and the median motor terminal latency index [(mTLI), (70.3%)], while the median-to-ulnar sensory action potential amplitude ratio (27%) and the median-thenar to ulnar-hypothenar motor action potential amplitude ratio (15%) were least sensitive tests. Sensory tests were more sensitive than motor NCSs. Combining mSDL with D4M-D4U, and mMDL with mTLI allowed for the detection of abnormalities in 150 (91%) and 132 (80%) hands, respectively. Measurements of all NCSs parameters were abnormal in obese than in non-obese patients when compared to the BMI.

The newer nerve conduction techniques and combining different NCSs tests are more sensitive than single conventional NCS test for the diagnosis of suspected CTS. Meanwhile, CTS is associated with increasing BMI.

^*This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

• References

• 1 Atroshi I, Gummesson C, Johnsson R, Ornstein E, Ranstam J, Rosén I. Prevalence of carpal tunnel syndrome in a general population. JAMA 1999; 282: 153-58 10.1001/jama.282.2.153 10411196
• 2 Stevens JC. AAEM minimonograph #26: the electrodiagnosis of carpal tunnel syndrome. Muscle Nerve 1997; 20: 1477-86 10.1002/(SICI)1097-4598(199712)20:12<1477::AID-MUS1>3.0.CO;2-5 9390659
• 3 Jablecki CK, Andary MT, So YT, Wilkins DE, Williams FH. Literature review of the usefulness of nerve conduction studies and electromyography for the evaluation of patients with carpal tunnel syndrome. Muscle Nerve 1993; 16: 1392-1414 10.1002/mus.880161219 8232399
• 4 Jablecki CK, Andary MT, Floeter MK, Miller RG, Quartly CA, Vennix MJ, Wilson JR. Second AAEM literature review of the usefulness of nerve conduction studies and needle electromyography for the evaluation of patients with carpal tunnel syndrome. Muscle Nerve 2002; 26 (suppl) S1-S53
• 5 American Association of Electrodiagnostic Medicine, American Academy of Neurology and American Academy of Physical Medicine and Rehabilitation. Practice parameter for electrodiagnostic studies in carpal tunnel syndrome: summary statement. Muscle Nerve 2002; 25: 918-22 10.1002/mus.10185 12115985
• 6 Bril V, Ellison R, Ngo M, Bergstrom B, Raynard D, Gin H. the Roche Neuropathy Study Group. Electrophysiological monitoring in clinical trials. Muscle Nerve 1998; 21: 1368-73 10.1002/(SICI)1097-4598(199811)21:11<1368::AID-MUS2>3.0.CO;2-7 9771658
• 7 Jackson DA, Clifford JC. Electrodiagnosis of mild carpal tunnel syndrome. Arch Phys Med Rehabil 1989; 70: 199-204 2923541
• 8 Uncini A, Di Muzio A, Awad J, Manante G, Tafuro M, Gambi D. Sensitivity of three median to ulnar comparative tests in diagnosis of mild carpal tunnel syndrome. Muscle Nerve 1993; 16: 1366-73 10.1002/mus.880161215 8232394
• 9 Lew HL, Wang L, Robinson LR. Test-retest reliability of combined sensory index: implications for diagnosing carpal tunnel syndrome. Muscle Nerve 2000; 23: 1261-1264 10.1002/1097-4598(200008)23:8<1261::AID-MUS16>3.0.CO;2-M 10918265
• 10 Sander HW, Quinto C, Saadeh PB, Chokroverty S. Sensitive median-ulnar motor comparative techniques in carpal tunnel syndrome. Muscle Nerve 1999; 22: 88-98 10.1002/(SICI)1097-4598(199901)22:1<88::AID-MUS13>3.0.CO;2-C 9883861
• 11 Chang MH, Wei SJ, Chiang HL, Wang HM, Hsieh PF, Huang SY. Comparison of motor conduction techniques in the diagnosis of carpal tunnel syndrome. Neurology 2002; 11: 1603-07
• 12 Kouyoumdjian JA, Zanetta DMT, Morita MPA. Evaluation of age, body mass index, and wrist index as risk factors for carpal tunnel syndrome severity. Muscle Nerve 2002; 25: 93-97 10.1002/mus.10007 11754190
• 13 Werner RA, Albers JW, Franzblau A, Armstrong TJ. The relationship between body mass index and the diagnosis of carpal tunnel syndrome. Muscle Nerve 1994; 17: 632-36 10.1002/mus.880170610 8196706
• 14 Quality Standards Subcommittee, American Academy of Neurology. Practice parameter for carpal tunnel syndrome (summary statement). Neurology 1993; 43: 2406-09 8232968
• 15 Smith NJ. Nerve conduction studies for carpal tunnel syndrome: essential prelude to surgery or unnecessary luxury?. J Hand Surg Br 2002; 27: 83-85 11895352
• 16 Rosen I. Neurophysiological diagnosis of the carpal tunnel syndrome: evaluation of neurographic techniques. Scand J Plast Reconstr Surg Hand Surg 1993; 27: 95-101 10.3109/02844319309079790 8351503
• 17 Monga TN, Shanks GL, Poole BJ. Sensory palmar stimulation in diagnosis of carpal tunnel syndrome. Arch Phys Med Rehabil 1985; 66: 598-600 4038024
• 18 Scelsa SN, Herskovitz S, Bieri P, Berger AR. Median mixed and sensory nerve conduction studies in carpal tunnel syndrome. Electroencephalogr Clin Neurophysiol 1998; 109: 268-73 10.1016/S0924-980X(98)00018-6 9741794
• 19 Charles N, Vial C, Chauplannaz G, Bady B. Clinical validation of antidromic stimulation of the ring finger in early electrodiagnosis of mild carpal tunnel syndrome. Electroencephalogr Clin Neurophysiol 1990; 76: 142-47 10.1016/0013-4694(90)90212-3 1697242
• 20 Cioni R, Passero S, Paradiso C, Giannini F, Battistini N, Rushworth G. Diagnostic specificity of sensory and motor nerve conduction variables in early detection of carpal tunnel syndrome. J Neurol 1989; 236: 208-13 10.1007/BF00314501 2760633
• 21 Kuntzer T. Carpal tunnel syndrome in 100 patients: sensitivity, specificity of multi-neurophysiological procedures and estimation of axonal loss of motor, sensory and sympathetic median nerve fibers. J Neurol Sci 1994; 127: 221-29 10.1016/0022-510X(94)90076-0 7707081
• 22 Wilson JR. Median mixed nerve conduction studies in the forearm: evidence against retrograde demyelination in carpal tunnel syndrome. J Clin Neurophysiol 1998; 15: 541-46 10.1097/00004691-199811000-00014 9881928
• 23 Chang MH, Wei SJ, Chiang HL, Wang HM, Hsieh PF, Huang SY. The cause of slowed forearm median conduction velocity in carpal tunnel syndrome: a Palmar stimulation study. Clin Neurophysiol 2002; 113 (7) 1072-76 10.1016/S1388-2457(02)00117-7 12088702
• 24 Robinson LR, Micklesen PJ, Wang L. Optimizing the number of tests for carpal tunnel syndrome. Muscle Nerve 2000; 23: 1880-1882 10.1002/1097-4598(200012)23:12<1880::AID-MUS14>3.0.CO;2-A 11102914