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1 원저접수번호 :09-029(2 차 -0710) 수근관증후군환자에서감각역치검사의진단적유용성 대구가톨릭의대신경과 이효민윤창효석정임이동국 Diagnostic Usefullness of Current Perception Threshold Test in Carpal Tunnel Syndrome Hyo Min Lee, MD, Chang Hyo Yoon, MD, Jung Im Seok, MD, Dong Kuck Lee, MD Department of Neurology, School of Medicine, Catholic University of Daegu, Daegu, Korea Background: Carpal tunnel syndrome (CTS) is the most commonly reported nerve entrapment syndrome. When performing routine nerve conduction studies (NCS) in clinically diagnosed CTS, we sometimes confronted with patients who have no definite electrophysiological evidence of CTS. Current perception threshold (CPT) test can evaluate the functioning of all major subpopulations of sensory nerve. The purpose of this study is to determine clinically usefulness of the CPT test in idiopathic CTS. Methods: We prospectively studied 60 patients (90 hands) who were clinically diagnosed as CTS. Involved hands were grouped into three clinical grades (mild, moderate and severe). NCS was done using a standard technique and equipment. CPT test was measured at the distal interphalangeal joint of second, third and fifth fingers with electrical current of 5 Hz, 250 Hz and 2,000 Hz in frequency. Results: Of 60 patients (90 hands), 8 (13.1%) were men and 52 (86.9%) were women. Mean age at evaluation was 56.00±8.94 years old. Positive rate of NCS and CPT was 0.80 (0.72, 0.88) and 0.61 (0.51, 0.71), respectively. Sensitive and specificity of CPT test was 0.49 and As the clinical severity of CTS deteriorate, CPT test showed abnormality in low frequency stimulation. Conclusions: CPT test is an effective and relatively simple procedure for measuring perception in CTS. But CTS test is difficulty and subjectively at interpretation. We suggested that the usefullness of CPT test is lower than NCS in diagnosis of CTS. J Korean Neurol Assoc 27(4): , 2009 Key Words: Current perception threshold, Carpal tunnel syndrome 서론 수근관증후군은정중신경이수근관에서압박손상을받아감각이변화되고진행시손에근력저하가나타나는증후군으로정중신경이지배하는손부위에저림증상이나타나며감각에대한민감도가변화된다. 신경이압박을받는초기에는감각이과민해지지만시간이지나면서차차둔해진다. 1 Received January 14, 2009 Revised October 19, 2009 Accepted October 19, 2009 *Dong Kuck Lee, MD Department of Neurology, School of Medicine, Catholic University of Daegu, Daemyeong 4-dong, Nam-gu, Daegu, , Korea Tel: Fax: dklee@cu.ac.kr 감각신경을검사하는방법은소리굽쇠로진동감각검사하기, 핀으로찌르기, 신경전도검사, current perception threshold (CPT) 검사등여러가지가있다. 그중핀이나소리굽쇠를사용하는방법은주관적인검사이므로할때마다결과가다를수있고검사자의편견이개입될수있다. 따라서정량적결과를얻을수있는신경전도검사나 CPT 검사등이감각신경을검사하는데쓰여져왔다. 신경전도검사는특발성 (idiopathic) 수근관증후군환자에서널리사용되는검사이다. 2 하지만주로굵고수초화된신경섬유인 A-beta 섬유만을측정하는검사이므로나머지다른신경섬유들의변화를측정하기에는어려움이있다. 또한검사하는동안환자는통증과불쾌감을느끼고, 피부의온도에따라측정값이영향을받으며, 부종이있는부위에서는검사의결과를신뢰 332

2 수근관증후군환자에서감각역치검사의진단적유용성 할수없다는단점이있다. 반면에 CPT 검사는 2000 Hz의전류로자극을줄때는촉각을전달하는 A-beta 섬유를선택적으로자극할수있으며, 250 Hz의전류는핀으로찌르기 (pinprick) 와관계되는 A-delta 섬유를자극하고, 5 Hz 전류로는통증과관계되는 C 섬유를선택적으로자극할수있다. 3-6 또한 CPT 의측정은피부의두께나온도에영향을적게받는다. 이러한장점으로인해외국에서는수근관증후군환자에서 CPT 검사의유용성에대한많은연구들이있었으나국내에서는연구가아직미미한실정이다. 본연구에서는임상적으로수근관증후군으로진단된환자에서신경전도검사와 CPT검사를하여그결과를각각비교분석하였다. 대상과방법 1. 대상 2006 년 12월 1일부터 2008 년 1월 30 일까지 3개월이상의손저림을주소로본원신경과를내원한환자중숙련된신경과의사가임상적으로수근관증후군으로진단한환자를대상으로신경전도검사와 CPT 검사를하였다. 신경학적진찰로서 Tinel sign 과 Phalen sign, 그리고근위축정도와근력정도를평가하였다. 신경병증을일으킬수있는대표적원인인당뇨병, 임신, 외상, 투석, 류마티스관절염, 통풍및갑상선기능저하증을가진환자등은대상에서제외하였다. 수근관증후군은임상증상의경중에따라경증, 중등증, 중증의세단계로대상을나누었다. 경증은정중신경이지배하는손의부위에감각이상만을나타내는경우로, 중등증은감각이상에근력저하가동반된경우로나누고, 엄지두덩 (thenar muscle) 위축이동반된경우를중증으로규정했다 방법 Oh 8 의방법에따라정중신경과척골신경의감각및운동신경전도검사를하였다. 그러나신경전도검사의결과중정중신경과더불어척골신경에도신경병증이확인되면말초신경병증으로진단하여연구대상에서제외하였다. 정중신경의신경전도검사를하여손바닥- 손목구간의감각신경전도속도의감소및운동신경의말단잠복기의지연이있을때수근관증후군으로진단하였다. 신경전도검사는 Medelec Synergy 기계를사용하였다. CPT 검사는 Neurometer R system 을사용하였다. 대수초성 A-beta 섬유에대해서는 2000 Hz, 소수초성 A-delta 섬유에 대해서는 250 Hz, 소비수초성 C 섬유에대해서는 5 Hz 로각각자극하였다. 7 자극은정중신경의감각신경이지배하는제2수지와제3수지및척골신경의감각신경이지배하는제5 수지에서시행하였다. 1.7 cm 벌어진직경 1 cm 크기인 2개의금 (gold) 전극사이에 0에서부터최대 9.99 mili-ampere 까지자극강도를올려가며환자가느끼는최소자극강도를반복자극하여그역치를기록하였다. 환자의주관적요소를배제하기위하여실제자극과유사한허 (false) 자극및반복자극과정을거쳤다. 이기록을 CPT analysis program 에의해계산된 CPT Grading parameter 를이용하여 0에서 12까지점수로나타내었다. 9 Grading parameter 에따르면 0은정상적인 CPT 를가진것이고 0에서 4까지는경한감각이상을나타내고, 7까지는지각과민 (hyperesthesia), 그이상은지각감퇴 (hypoesthesia) 를나타낸다. 이수치는빈도에따른각각의점수가아닌종합수치로이점수에따라 CPT 이상을가진군을세단계로나누어지각이증가했는지감퇴했는지모르는경한이상은경증 (mild) 군, 지각과민은중등증 (moderate) 군, 지각감퇴는중증 (severe) 군으로설정하였다. 경중의설정은본교실에서임의로설정한것으로민감도와특이도알아보기위해설정하였다. 또한본연구에서는정상 CPT 를 0으로하고이상 CPT 를 1로표시하여이코드를자극빈도에따른이상유무를표시하는데사용하였다. 예를들어 110 또는 101 에서첫번째숫자는 2000 Hz 로자극했을때 CPT 의이상유무를나타내고, 두번째숫자는 250 Hz, 세번째숫자는 5 Hz로자극했을때그결과를의미한다. 이러한규칙으로여덟가지의형태의조합을만들어자극빈도에따른 CPT 의이상유무를표시하였다. 결과분석은임상적으로수근관증후군으로진단된연구대상에서성별과연령등의역학을분석하고신경전도검사와 CPT 검사의양성률을비교해보았다. 또한임상증상의경중에따른감각역치검사결과를분석하였다. 측정값의분석은 SPSS (window data editor version 14.0) 를사용하였다. 사용된통계분석방법은 Chi-square test/roc curve, sensitivity, specificity이다. 결과 대상환자들의역학은총 60명중남자 8명, 여자 52명으로여성이월등히많은수를차지했다. 평균연령은 56.0±8.94 세로남녀간의차이는없었다. 수근관증후군으로진단된수지의비율은양손이 30명, 왼손이 16명, 오른손이 14명을차지했다 (Table 1). 연구대상환자들을임상증상의경중에따라 3단계로나누어, J Korean Neurol Assoc Volume 27 No. 4,

이효민윤창효석정임이동국 Table 1. Baseline of carpal tunnel syndrome patients (n=60) Baseline n (%) Sex Male 8 (13.1) Female 52 (86.9) Age mean(s.d) 56.00 (8.94) Site Left 16 (26.7) Right 14 (23.3) Both 30 (50.

3 이효민윤창효석정임이동국 Table 1. Baseline of carpal tunnel syndrome patients (n=60) Baseline n (%) Sex Male 8 (13.1) Female 52 (86.9) Age mean(s.d) (8.94) Site Left 16 (26.7) Right 14 (23.3) Both 30 (50.0) Table 2. Clinical characteristics of carpal tunnel syndrome patient s hands (n=90) Assessment tool n (%) Clinical severity Mild 51 (56.7) Moderate 32 (35.6) Severe 7 (7.8) NCS Normal 18 (20.0) Abnormal 72 (80.0) CPT Normal 35 (38.9) Abnormal 55 (61.1) CPT grade Normal 35 (38.9) Mild 14 (15.6) Moderate 23 (25.6) Severe 18 (20.0) NCS; nerve conduction study, CPT; current perception threshhold 신경전도검사와 CPT 검사결과에따라분류한결과는 Table 2 와같다. 임상증상의경중에따라경증군이 51(56.7%), 중등증군이 32(35.6%), 중증군이 7(7.8%) 예로나타났으며, 임상적으로진단된환자들에대한 CPT검사와신경전도검사의양성률은 95% 신뢰구간에서각각 0.61(0.51, 0.71) 과 0.80(0.72, 0.88) 을보였다 (Table 3). CPT 검사의결과를임상증상의경중에따라분석해 ROC curve 와민감도와특이도를얻었다 (Fig. 1). AUC (Area Under Curve) 는 이었고민감도와특이도는각각 과 로분석되었다 Hz, 250 Hz, 5 Hz 의빈도로각각자극을가하여얻은 CPT 의이상유무를임상증상의경중에따라정리하여보면 Table 4와같다. 여덟가지형태의조합중 <000>,<100>,<110>,<111> 군은이상 CPT 가높은빈도자극에서낮은빈도자극으로갈수록나타나는것을의미한다. 이군을 *00 과 11* 로나누어임상증상의경중과의관계곡선을그리면 Fig. 2가된다. *00 과 11* 두군으 Table 3. Positive rate of NCS and CPT in carpal tunnel syndrome patients Variable positive rate 95% Confidence interval for positive rate (LB, UB)+ NCS 0.80 (0.72, 0.88) CPT 0.61 (0.51, 0.71) NCS; nerve conduction study, CPT; current perception threshhold, LB; lower boundary, UB; upper boundary Table 4. Occurrence of eight types in each group of hands, by severity (normal: 0, abnormal: 1) Type clinical severity mild Moderate severe (41.2) 11 (34.4) 2 (28.6) (13.7) 3 (9.4) 2 (28.6) (13.7) 5 (15.6) 2 (28.6) (9.8) 5 (15.6) 1 (14.3) (5.9) 2 (6.3) 0 (0.0) (11.8) 4 (12.5) 0 (0.0) (3.9) 2 (6.3) 0 (0.0) (0.0) 0 (0.0) 0 (0.0) Total 51 (100.0) 32 (100.0) 7 (100.0) First digit; 2000 Hz, second; 250 Hz, third; 5 Hz 로나누어결과분석을한이유는기존보고에서증상초기에는고빈도에서 CPT 이상을보이나수근관증후군이악화될수록저빈도에서이상을보이므로두군은증상의진행정도를대표한다고볼수있기때문이다. 본연구에서도 *00 군은임상증상이악화될수록그비율이줄어들고 (p<0.001), 11* 군은임상증상이악화될수록비율이증가하는분포를보인다 (p=0.065). 다시말해임상증상이악화될수록낮은빈도자극에이상 CPT 비율이높아짐을알수있다. Figure 1. AUC (area under curve). AUC: 0.528/sensitivity: 0.487, specificity:

4 수근관증후군환자에서감각역치검사의진단적유용성 Figure 2. The percentage of [*00] and [11*] type in each group (sequence: 2000, 250, 5 Hz CPT; 0, normal; 1, abnormal; *either). The percentage of [*00] significantly decreased (Chi-square test: p= 0.001), while the percentage of [11*] increased (Chisquare test: p=0.086) as clinical severity progressed. 고찰 CPT 검사는일정수준의전기자극을피부에가해말초감각신경에서느끼는최소자극을인식하는강도를측정하는검사로감각신경섬유의손상정도를파악할수있다고알려져있다. 10 감각신경의전기자극으로감각신경의기능을평가하는방법이기존에도많이있었으나 CPT 검사가기존방법과다른점은다빈도 (multiple frequency) 의일정한교류전류를 sinusoidal wave 형태로자극을주는것으로피부저항에가장적은영향을받으면서원하는신경섬유만자극할수있는장점이있는것으로알려져있다. 3-6 수근관증후군의진단은임상증상및신경학적검사로가능하지만, 동통, 둔감및이상감각등의증상이다른질환에서도나타나기때문에전기생리학적검사가진단에매우중요하다. 그중에서도신경전도검사가수근관증후군진단에서가장널리사용되고있다. 2 신경전도검사에서진단기준은손가락과손목사이에서정중감각신경의전도속도감소및정중운동신경의말단잠복기지연등이흔히이용된다. 8 수근관증후군에서 CPT 검사에대한연구는 1989 년 Katims 등에의하여처음시행되었다. 1 그후국외에서수차례보고가있었고국내에서는 2000 년도에한차례보고된바있다 그동안의국외보고들은주로산업노동자들사이에수근관증후관에대한조사가이루어졌다. 또한일본에서의보고는수근관증후군의임상경중에따라 CPT 검사의빈도에따른감각이상이고빈도에서저빈도로진행하는양상을보였고, 진단적민감도와특이도도 NCS 에못지않은것으로보고했다 그러나여러연구를종합해보면이제까지의연구결과는 CPT 검사가수근관증후군의진단법으로사용할수있을지에관해서는논란의여 지가있는것으로나타났다. 일부연구에서는수근관증후군을진단하는방법으로이미확립되어있는신경전도검사와비교해높은상관관계를가지는것으로나타났으나일부에서는그렇지못하다는연구결과도있다. 16 본연구에서는숙련된신경과의사에의해임상적으로수근관증후군으로진단된환자를대상으로신경전도검사와 CPT 검사를하여각각에대한양성률을구하였다. 연구를계획할당시의예상은다양한굵기의신경섬유를측정할수있는 CPT 검사가굵고수초화된신경섬유만측정하는신경전도검사보다더높은양성률을가질것으로추측했었으나연구결과는그렇지못했다. 이러한결과의해석은두가지로생각해볼수있겠다. 첫째수근관증후관과같은압박성신경병증은주로수초화된굵은신경이손상받는것으로알려져있다 따라서원칙적으로수초화된굵은신경을주로검사하는신경전도검사의양성률이 CPT 검사에비해못하지않을것이다. 두번째는 CPT 검사자체의문제점을생각해볼수있다. 검사자체의주관적요소와해석의문제로인한오류일가능성이그것이다. CPT 검사는대조군의 CPT 가다양하고, 정상과비정상을구분하는해석방법이복잡하기때문에일반적으로사용되어지기어렵다고지적되어왔다. 20 또한감각이상의역치만으로신경이손상된해부학적위치를결정하는데는제한점이있다. 본연구에서도정상대조군을설정하지않고제조사의해석프로그램에의해구해진결과를사용하였기때문에오류가있을가능성을배제할수없다. 그러나저자들은이번연구결과를분석한결과수근관증후군이초기에굵고수초화된신경이손상되고병이진행함에따라가늘고수초화가되지않은신경이손상이받는다는기존의결과를재확인할수있었다. 21 이를통해 CPT 검사가수근관증후 J Korean Neurol Assoc Volume 27 No. 4,

5 이효민윤창효석정임이동국 군의신경손상의정도를평가하는데는어느정도는유용함을알수있었다. 수근관증후군진단에있어 CPT 검사는진단의양성률이신경전도검사에비해떨어지고결과해석과검사방법의주관성등의문제가있으나신경전도검사보다환자가느끼는불편감이적고, 특히소신경섬유손상에대한분별력이있으며, 검사가간단하다는점을고려할때신경전도검사가이루어지기힘든상황에서보조적진단도구또는병의경과관찰에는유용성이있을것으로생각된다. 그러므로앞으로 CPT 검사의정확한임상적유용성을알기위해서는정상대조군의설정이이루어진대규모의연구가더필요할것으로생각된다. REFERENCES 1. Katims JJ, Rouvelas P, Sadler BT, Weseley SA. Current perception threshold. Reproducibility and comparison with nerve conduction in evaluation of carpal tunnel syndrome. ASAIO Trans 1989; 35: Spinner RJ, Bachman JW, Amandio PC. The many faces of carpal tunnel syndrome. Mayo Clin Proc 1989;64: Appenzeller O, Wood SC, Appenzeller T. Pentoxifyline, altitude and peripheral nerve function. Annals of Sports Med 1988;4: Dotson RM. Clinical neurophysiology laboratory tests to assess the nociceptive system in humans. J Clin Neurophysiol 1997;14: Liu S, Kopacz KJ, Carpenter RL. Quantitative assessment of differential sensory nerve block after lidocaine spinal anesthesia. Anesthesiology 1995;82: Tay B, Wallace MS, Irving G. Quantitatiive assessment of differential sensory blockade after lumbar epidural lidocaine. Anesth Analg 1997;84: Mackinnon SE, Dellon AL. Carpal tunnel syndrome. In: Mackinnon SE, Dellon AL, editors. Surgery of the peripheral nerve. New York: Thieme Medical Publishers; 1988; Oh SJ. Clinical Electromyography : Nerve conduction studies. 2nd ed. Boltimore: Williams & Wilkins, 1993; Copyright R 1999~2002 Neurotron, Inc-Baltimore, MD USA h t t p : / / w w w. n e u r o t r o n. c o m 10. Katims JJ, Long DM, Ng LK. Transcutaneous nerve stimulation. Frequency and waveform specificity in humans. Appl Neurophysiol 1986; 49: Katims JJ, Patil AS, Rendell M, Rouvelas P, Sadler B, Weseley SA, et al, Current perception threshold screening for carpal tunnel syndrome. Arch Environ Health 1991;46: Nakazumi Y, Hamasaki M. Electrophysiological studies and physical examinations in entrapment neuropathy: sensory and motor functions compensation for the central nervous system in cases with peripheral nerve damage. Electromyogr Clin Neurophysiol 2001;41: Nishimura A, Ogura T, Hase H, Makinodan A, Hojo T, Katsumi Y, et al. Evaluation of sensory function after median nerve decompression in carpal tunnel syndrome using the current perception threshold test. J Orthop Sci 2003;8: Nishimura A, Ogura T, Hase H, Makinodan A, Hojo T, Katsumi Y, et al. Objective evaluation of sensory function in patients with carpal tunnel syndrome using the current perception threshold. J Orthop Sci 2003;8: Kang YK, Seo KS, Park EM, Lee CH. Quantitive measurement of current perception threshold in carpal tunnel syndrome. J Korean Acad. Of Rehab Med 2004;24: Franzblau A, Werner RA, Johnston E, Torrey S. Evaluation of current perception threshold testing as a screening procedure for carpal tunnel syndrome among industrial workers. J Occup Med 1994;36: Jefferson D, Eames RA. Subclinical entrapment of the lateral femoral cutaneous nerve: an autopsy study. Muscle Nerve 1979;2: Mackinnon SE, Dellon AL, Hudson AR, Hunter DA. Chronic human nerve compression: a histological assessment. Neuropathol Appl Neurobiol 1986;12: Neary D, Ochoa J, Gilliatt RW. Sub-clinical entrapment neuropathy in man. J Neurol Sci 1975;24: Technology review: the Neurometer Current Perception Threshold (CPT). AAEM Equipment and Computer Committee. American Association of Electrodiagnostic Medicine. Muscle Nerve 1999;22: Nishimura A, Ogura T, Hase H, Makinodan A, Hojo T, Katsumi Y, et al. A correlative eletrophysiologic study of nerve fiber involvement in carpal tunnel syndrome using current perception thresholds. Clin Neurolphysiol 2004;115:

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012임수진 Received : 2012. 11. 27 Reviewed : 2012. 12. 10 Accepted : 2012. 12. 12 A Clinical Study on Effect of Electro-acupuncture Treatment for Low Back Pain and Radicular Pain in Patients Diagnosed with Lumbar