Kaohsiung J Med Sci March 2004 • Vol 20 • No 3 106
P
HYSICIAN
P
RACTICES
IN
THE
D
IAGNOSIS
OF
C
ARPAL
T
UNNEL
S
YNDROME
AT
A
M
EDICAL
C
ENTER
IN
S
OUTHERN
T
AIWAN
Chwen-Yng Su, Wen-Lung Liang,1 Mei-Jin Chen-Sea,2 Chin-Wei Liu,1 Mao-Hsiung Huang,1 and Yung-Chang Lai3
School of Occupational Therapy, 1Department of Rehabilitation Medicine, and
3
Graduate Institute of Occupational Safety and Health, Kaohsiung Medical University, Kaohsiung, and 2Department of Occupational Therapy,
National Cheng-Kung University, Tainan, Taiwan.
Carpal tunnel syndrome (CTS) is the most common neurologic entrapment disorder diagnosed in the upper limb. Nevertheless, there is still debate about the most reliable test that should be performed to diagnose CTS. Much of the argument has been drawn from the opinions of individuals or groups with varying degrees of expertise in the field; little has been based on actual data. The purpose of this study was to investigate the diagnostic patterns of CTS in an academic medical setting in southern Taiwan. The charts of 1,050 patients with a diagnosis of CTS over a 1-year period (2001–2002) were retrospectively reviewed. Data on 622 patients with new-onset CTS were included in the analysis. On the patient’s initial visit, physicians made a diagnosis of CTS in 34.9% of cases solely on the basis of the history of symptoms without resort to provocative tests, while 8.7% of cases were diagnosed on the basis of symptom characteristics alone in spite of negative provocative tests. A CTS diagnosis was given according to symptoms and positive provocative tests in 55% of cases. Apart from these, CTS diagnosis remained unchanged in 27.3% of cases without electrodiagnostic signs of CTS during follow-up visits. An average of 1.6 diagnostic maneuvers were conducted for CTS patients, with nerve conduction velocity (NCV) studies (516 cases) being the most frequently performed, followed by Tinel’s sign (350 cases) and Phalen’s test (102 cases). Our findings imply that physicians are inclined to base their diagnosis on clinical history and physical examination for patients with suspected CTS. Clear guidelines regarding the indications for referral for NCV studies should be established in response to the increased concerns about the cost effectiveness of diagnostic tests.
Key Words: carpal tunnel syndrome, Phalen’s test, Tinel’s sign, nerve conduction studies
(Kaohsiung J Med Sci 2004;20:106–114)
Received: November 7, 2003 Accepted: January 6, 2004 Address correspondence and reprint requests to: Dr. Yung-Chang Lai, Graduate Institute of Occupational Safety and Health, Kaoh-siung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan.
E-mail: [email protected]
Of the upper-extremity peripheral entrapment neuro-pathies, carpal tunnel syndrome (CTS) remains the most commonly seen. CTS is the symptomatic presentation of median nerve compression at the wrist resulting from a
variety of causes, such as genetic predisposition, injuries and trauma, and systemic or physiologic disorders, as well as repetitive and forceful motions of the wrist which, in turn, may lead to elevated pressure in the carpal tunnel [1]. The reported prevalence of CTS in the general population varies from 1% in the USA to 2.7% in Sweden [2,3]. This discrepancy may be mainly attributable to the different case definitions used to classify medical diagnoses of CTS in these studies. CTS prevalence rates peak in middle age or later [2,3]. Women have a greater risk of CTS compared to men in various industries or in the general population, with
two to three times more women than men suffering from CTS [3].
The clinical features of CTS include numbness, pain, tingling or some combination of these symptoms in the area supplied by the terminal cutaneous branches of the median nerve (anterior surface of the first three digits and the radial portion of the ring finger). Patients with CTS may experience diminished dexterity and weakness of the hand [4]; in longstanding cases, even a loss of protective sensation was noted [5]. CTS is usually diagnosed from symptoms, provocative testing, and electrodiagnostic studies, such as nerve conduction velocity (NCV) test and electromyo-graphy, individually or in various combinations. Yet, findings in relation to the diagnostic accuracy of clinical tests are controversial. Phalen’s wrist flexion test and Tinel’s test of nerve percussion are commonly used provocative tests. Their sensitivities range from 48% to 85% (Phalen’s test) and from 25% to 67% (Tinel’s sign), and specificities from 55% to 89% and from 59% to 94%, respectively [6,7]. Overall, Phalen’s wrist flexion test is the most sensitive provocative test for the diagnosis of CTS, while Tinel’s sign is the most specific and the least sensitive [7]. Mondelli et al accounted for the disparities in the discriminating values of provocative tests, stating that the positive sensory symptoms, such as pain and paresthesia, provoked from test maneuvers that increase intracarpal pressure probably weaken in advanced stages of CTS due to the progressive axonal loss caused by continuous compression [8]. Con-sequently, it was suggested that generalizability of re-search findings in this sphere should take into account the clinical and electrophysiologic severity of CTS.
Likewise, a dispute arises over the usefulness of NCV studies for the evaluation of CTS. One line of research indicates that median sensory and motor NCV studies are valid in confirming a clinical diagnosis of CTS, with reported sensitivities of 49% to 84%, and specificities of 95% to 99% [9,10]. DeKrom and colleagues proposed that patients with clinically suspected CTS should be referred directly for neurophysiologic examination in view of the low validity associated with clinical signs and provocative tests [6]. Nonetheless, another line of research cautions the use of electrodiagnostic studies alone because of the high prevalence of abnormal median nerve conduction within the carpal tunnel without corresponding symptoms (i.e. false positives) in healthy worker populations [11]. In addition, false-negative results may occur partly because the condition is intermittent [12] and partly because CTS, particularly in the early stages, selectively affects the small, unmyelinated fibers that are undetectable by NCV studies,
which evaluate large-diameter, myelinated sensory and motor nerve fibers [13]. After reviewing a multitude of published reports in connection with the diagnosis of CTS, experts from several medical organizations in fields such as neurology, electrodiagnostic medicine, occupational medicine, and physical medicine and rehabilitation have reached consensus that the combination of electrodiagnostic study findings and symptom characteristics offers the most accurate method to diagnose CTS [14].
These variations in the diagnostic validity of provocative and electrophysiologic tests can complicate diagnostic efforts and should be considered in the diagnostic process for CTS. Research pertinent to the practice patterns of physicians in the diagnosis of patients with symptoms compatible with CTS is scanty, and some of the existing data are inconsis-tent. One study observed that NCV testing was performed in 282 of 290 cases (97%) with clinical evidence of CTS [15]. Similar findings were obtained in a population-based CTS incidence study, in which 98% of physicians reported us-ing electrophysiologic tests to diagnose CTS [16]. Converse-ly, underutilization of NCV examination in patients with probable CTS is also reported. For example, Phalen believed that electrodiagnostic procedures are not usually necessary to make the diagnosis of CTS, and that an accurate diagnosis may be established by noting the presence of one or more of three clinical signs: a positive Phalen’s test, Tinel’s sign, and a sensory deficit in the territory of the median nerve [17]. In a population-based study over a 20-year period, Stevens reflected that approximately 50% of patients in Rochester, Minnesota, USA, who were thought to have CTS were actually referred for electrodiagnostic testing [18]. In a survey of 467 hand surgeons in the American Society for Surgery of the Hand, 37.9% used electrodiagnostic test-ing “always”; 26.3%, “usually”; 33.2%, “occasionally”; and 1.5%, “never” [19]. Other authors found that even fewer patients diagnosed with CTS and treated using surgery were referred for electrodiagnostic testing [20]. These conflicting diagnostic practices might be partly explained by clinicians’ beliefs about the efficacy of the various diagnostic tests. In light of the cost containment and efficiency promoted by the health insurance system, an understanding of the diagnostic tests utilized by practicing physicians contributes significantly to the assessment of the quality and cost of care for CTS. Unfortunately, no direct comparison can be made in this regard because similar studies have not been undertaken in Taiwan.
The purposes of this study were twofold: to examine the current practice patterns of hospital-based physicians in evaluating patients with clinically suggestive CTS, and to
investigate the diagnostic accuracy of provocative tests in comparison with NCV findings.
M
ATERIALSANDM
ETHODSData were retrospectively collected from a computerized patient database at a large urban medical center affiliated with a university school of medicine in southern Taiwan. Consecutive cases with a diagnosis of CTS (International Classification of Diseases, 9th Revision Clinical Modifica-tion, code 354.00) [21] in the hospital discharge register be-tween April 1, 2001, and March 31, 2002, were considered. Patients were included in the analysis if they had new-onset CTS and complete documentation of the patient visit for CTS problems. Exclusion criteria included an underlying disease such as rheumatoid arthritis, diabetes, gout or hy-pothyroidism, renal dialysis, pregnancy, space-occupying lesions such as a ganglion, previous carpal tunnel release, and previous fracture of the distal radius. The medical charts were reviewed by an experienced occupational therapist together with two trained research assistants. Information pertaining to age, gender, affected hands, diagnosis, diagnosing physician, types of diagnostic tests, and results of diagnostic maneuvers was collected.
There are two electrodiagnostic laboratories in the hospital, one in the Department of Neurology and the other in the Department of Physical Medicine and Rehabilita-tion. Physicians from the two departments respond to consultation requests for electrodiagnostic testing throughout the hospital. In patients clinically suspected of having CTS, both laboratories performed electrophysiologic studies in accordance with a uniform operating protocol by means of Dantec Keypoint Version 4 (Dantec Electronics, Tonsbakken, Skovlunde, Denmark) electromyography. NCV evaluation of CTS in this medical center comprised bilateral median and ulnar distal sensory and motor latencies. Factory-set filter combinations were 20 Hz to 2 kHz for surface sensory recordings and 2 Hz to 10 kHz for surface motor recordings. The skin temperature of the palm was maintained above 31$C. In all cases, median the-nar and ulthe-nar hypothethe-nar motor latencies were examined by placing the active recording surface electrodes over the midpoint of the abductor pollicis brevis and abductor digiti minimi. The reference electrode was placed over the proxi-mal phalanx of the thumb for the median nerve and over the proximal phalanx of the small finger for the ulnar nerve. Supramaximal distal stimulation was delivered at the wrist over the respective nerve 8 cm proximal to the active
surface electrode. Proximal stimulation was applied to the median nerve between the biceps tendon and the medial epicondyle at the elbow, and to the ulnar nerve between the medial epicondyle and the triceps tendon. Median and ulnar sensory nerve studies to the index finger and small finger, respectively, were conducted using standard 14 cm antidromic techniques. The active recording surface elec-trodes were placed around the proximal interphalangeal (PIP) joints and the reference electrodes were placed around the distal interphalangeal (DIP) joints of the same digits. Wrist stimulation was applied to the median and ulnar nerves at a point 14 cm proximal to the PIP joints of the second and fifth digits, respectively. Supramaximal proximal stimulation was applied to the median nerve between the biceps tendon and the medial epicondyle at the elbow, and to the ulnar nerve between the medial epicondyle and the triceps tendon. The electrodiagnostic criteria for CTS were a median digit II and ulnar digit V sensory latency difference of more than 0.4 ms, a median sensory latency greater than 3.5 ms, a median sensory velocity less than 40 m/s, and a median distal motor latency greater than 4.0 ms.
All data were analyzed using the Statistical Package for the Social Sciences (SPSS) for Windows, version 11.0 (SPSS Inc, Chicago, IL, USA). Frequency distribution was used to illustrate the types and numbers of diagnostic tests rendered. Chi-squared analysis was used to determine the association between provocative and NCV test results.
R
ESULTSOf 1,050 consecutive patients in the study period, 622 were included in the study population, 159 men (25.6%) and 463 women (74.4%). Women outnumbered men by about 2.91 to 1. Patients were aged between 17 and 88 years, with a mean age of 50.31 ( 11.93 years. Patients were grouped into six categories by age: less than 25, 25–34, 35–44, 45–54, 55– 64, and at least 65 years. The prevalence of CTS in these categories was 1.6%, 7.4%, 19.8%, 37.3%, 24.0%, and 10.0%, respectively (r2 = 315.76, p = 0.000). The greatest frequency was
found in the 45–54 years old category, followed by the 55– 64 age group. Patients presenting with symptoms in both hands (52.4%) had a higher prevalence of CTS than patients with either right- (26.4%) or left-hand (21.2%) complaints (r2 = 104.35, p = 0.000).
Among the 622 cases with a diagnosis of CTS, sensory disturbance in the median nerve distribution, such as numbness and paresthesia, nocturnal pain, and muscle atrophy, was reported by 84.1%, 19.5%, and 3.7% of all
patients, respectively. Clinicians recorded one or more diagnostic tests in 96.8% of patients, the most frequent of which were NCV studies (516 cases) and Tinel’s sign (350 cases). Phalen’s test was infrequently performed (102 cases) (Table 1). Specifically, 45.7% of patients underwent one test, 47.8% underwent two tests, and 6.5% underwent three diagnostic tests. An average of 1.6 diagnostic maneuvers were conducted for patients with CTS symptoms. Similar results were obtained for men and women. Surprisingly, none of the patients had been examined using any sensibility tests.
The process of clinical decision making among physicians in their diagnostic formulation was analyzed. No patients underwent NCV studies during their first visit, and NCV consultation did not alter the clinical impression about a patient’s diagnosis in 27.3% (141/516) of cases in which NCV tests were negative. Stated another way, physicians determined a CTS diagnosis purely on clinical grounds during the initial visit. In particular, physicians made a diagnosis solely according to the history of symptoms in 34.9% (217/622) of cases without the use of provocative tests, while 8.7% (54/622) of cases were diagnosed on the basis of symptom characteristics alone regardless of nega-tive provocanega-tive tests (i.e. neganega-tive Tinel’s sign, Phalen’s test, or both) (Table 2). In the same vein, physicians arrived at a diagnosis based on symptoms in association with positive provocative tests (i.e. positive Tinel’s sign, Phalen’s test, or both) in 54.8% (341/622) of cases. In 86.7% (351/405) of patients, at least one provocative test was positive. Among these, Tinel’s sign was positive in 311 of 350 cases, whereas Phalen’s test was positive in 76 of 102 cases.
Neurologists established a diagnosis of CTS in 60.1% of cases, followed by physiatrists (15.9%), neurosurgeons (8.0%), orthopedists (7.4%), internists (4.5%), occupational medicine physicians (1.9%), family medicine physicians
Table 2. Results of provocative tests in patients with sus-pected carpal tunnel syndrome
Test Number of patients
(n = 405)
Tinel’s sign (+) 267
Tinel’s sign (–) 36
Phalen’s test (+) 38
Phalen’s test (–) 17
Tinel’s sign (+) and Phalen’s test (–) 8 Tinel’s sign (–) and Phalen’s test (+) 2 Tinel’s sign (+) and Phalen’s test (+) 36 Tinel’s sign (–) and Phalen’s test (–) 1
Table 1. Frequency of provocative tests and nerve conduc-tion velocity (NCV) tests performed in patients with sus-pected carpal tunnel syndrome
Test Number of patients
(n = 602)
Phalen’s test 21
Tinel’s sign 57
NCV test 197
Phalen’s test and Tinel’s sign 8
Phalen’s test and NCV test 34
Tinel’s sign and NCV test 246
Tinel’s sign, Phalen’s test and NCV test 39
(1.1%), anesthesiologists (0.6%), and plastic surgeons (0.3%). The percentage of NCV referrals among all CTS patients seen by each discipline was calculated to determine the referral rate (Figure 1). In the departments of plastic surgery, family medicine, and occupational medicine, all patients were referred for NCV testing, whereas the pain clinic (25%) and orthopedic department (37%) had the lowest proportion of referrals. Figure 2 illustrates the
per-Figure 1. Distribution of nerve conduction velocity (NCV) referrals among physicians of different specialties.
100 80 60 40 20 0 Percentage of patients No Yes NCV referral status
Rehabilitation Neurology Orthopedics Pain clinic Neurosurgery Plastic surgery Family medicine Occupational Internal medicine
centage of provocative tests administered by physicians in different specialties. The rehabilitation department per-formed the highest percentage of provocative tests (83%), followed by the pain clinic (75%), whereas the lowest percen-tages were found in the departments of family medicine and occupational medicine.
The sensitivity of NCV testing was 74% (145/197) (95% confidence interval, 95% CI, 0.67–0.79), using clinical diagnosis as the criterion (Table 3). Chi-squared analysis revealed significant correlation between electrodiagnostic testing and Tinel’s sign (r2 = 4.62, p = 0.03), whereas no significant association emerged between NCV studies and Phalen’s test (r2 = 1.98, p = 0.16). The sensitivity (proportion of patients with CTS who had positive NCV findings) of Tinel’s sign was 91% (95% CI, 0.87–0.94) (Table 4), and that of Phalen’s test was 73% (95% CI, 0.60–0.83) (Table 5).
D
ISCUSSIONCTS is the most frequent compression neuropathy seen by clinicians, affecting the quality of life of its victims and their families; it is often a cause of failure to return to work [22]. As a result, accurate diagnosis could have a tremendous effect on health outcomes for patients and on health care costs. To our knowledge, this is the first study describing how patients with symptoms of CTS are evaluated by prac-titioners from a broad spectrum of specialties in Taiwan. The age- and sex-specific rates of new-onset CTS observed in this analysis are generally consistent with two population-based prevalence reports from other countries [2], in that females had a higher prevalence of CTS than males, and the middle-aged had a higher prevalence than people of other age groups. Bilateral symptoms have been reported in 59% to 87% of patients [23], and were found in 52% of patients in our study. Among those presenting with unilateral involve-ment, the right hand was more susceptible to CTS than the left. However, our study was retrospective in nature and no information was obtained concerning handedness.
Most CTS patients (84%) experienced paresthesia and numbness in the digits innervated by the median nerve in this study cohort, and these symptoms seemed to be the main reasons that brought patients to seek medical help. This figure is coincident with earlier data that a sensory disturbance in the distribution of the median nerve distal to the wrist is the most constant clinical finding in CTS patients [17]. A review of the literature indicated that CTS is defined as either symptoms plus physical signs or symptoms plus positive NCV studies [15]. Our findings disclosed that physicians relied solely on the symptom features in making the diagnosis of CTS in 43.6% of cases, while 54.8% of cases were diagnosed based on the presence of symptoms cou-pled with positive physical examination findings. Electro-diagnostic consultation after history taking and provoca-tive tests seemed to contribute little to clinical decision making, since no statements regarding a change of diagnosis were found on patients’ charts in the presence of negative NCV studies. As a matter of fact, physicians did not rule out the CTS diagnosis in 27.3% of cases in which NCV tests were within normal limits.
Table 3. Sensitivity of nerve conduction velocity (NCV) studies using clinical diagnosis as the criterion standard Physician’s diagnosis based on clinical grounds (n = 622) Sensitivity
NCV positive (n = 375) 145 73.6%
NCV negative (n = 141) 52
Figure 2. Frequency distribution of provocative tests performed by physicians from different specialties.
100 80 60 40 20 0 Percentage of patients No Yes
Provocative tests performed Rehabilitation Neurology Orthopedics Pain clinic Neurosurgery Plastic surgery Family medicine Occupational Internal medicine
There is great variability in the adherence of NCV studies to practice standards, especially in the case of diagnosis in subjects with classic or probable symptoms of CTS in conjunction with a negative electrodiagnostic find-ing. In a prospective study evaluating the value of electrodiagnostic consultation for patients with upper-extremity nerve complaints, 42% of diagnoses were altered after electrodiagnostic testing [15]. In the same work, the complexity of the patient’s medical history and the lack of severity or specificity of the patient’s complaint related significantly to the final diagnostic certainty. On the contrary, a number of studies support the view that CTS is a clinical diagnosis taking into account the good or excellent results of operative treatment in spite of normal NCV studies [24]. For example, based on a comprehensive review, Jordan et al concluded that electrodiagnostic studies are not useful in confirming the diagnosis in most cases of CTS where the symptoms are well defined, thanks to the low sensitivity of NCV testing, and that electrodiagnostic test results cannot be justified as providing a prognostic indicator of surgical outcome in CTS [25]. Our findings showed that physicians in the busy ambulatory setting tend to diagnose CTS on clinical findings only, since clinical history and provocative tests are more easily performed than electrodiagnostic studies in this type of setting. Generalization of this result awaits further study from a multicenter project on the diagnostic strategies employed by physicians for patients with clinically suspected CTS.
With regard to the clinical disciplines of the diagnosing physicians, neurologists provided the highest diagnostic
yield, followed by physiatrists, who together accounted for 76% of all CTS diagnoses. The proportions of doctors diagnosing cases were low among internists, occupation-al medicine physicians, family medicine physicians, anesthesiologists, and plastic surgeons. This finding is at variance with the limited number of previous reports available. A countywide study in California stated that the greatest number of CTS cases was seen by chiropractors (23%), neurologists (14%), internists (19%), and family medicine physicians (9%) [26]. In surveillance of work-related CTS, Davis et al found that among all physicians, orthopedic specialists together with occupational medicine physicians reported 45% of all CTS cases to the Massachusetts Department of Public Health [27]. Our findings showed that patients with CTS were more likely to opt for care from physicians in the specialty areas of neurology and rehabili-tation when suffering from feelings of numbness or tingling in their hands. However, a nationwide investigation on the frequency of patient visits for CTS within each clinical specialty is needed to substantiate this phenomenon.
The NCV test was the most frequently performed (85.7%), followed by Tinel’s sign (58.1%) and Phalen’s test (16.9%). The departments of plastic surgery, family medicine, and occupational medicine achieved an NCV referral rate of 100%. Different NCV referral rates among physi-cians were seen in other studies. Lo et al found that 71.8% of NCV referrals were from family medicine physicians, whereas orthopedic and plastic surgeons referred 19.8% of all patients [28]. Mondelli et al documented that most NCV cases were referred by general practitioners (57.8%), followed by rheumatologists (10.1%), orthopedists (9.4%), physiatrists (6.5%), neurosurgeons (6.4%), and other specialists (5.3%); the fewest were referred by neurologists (4.4%) [16]. Generally speaking, decisions to refer for NCV studies after history taking and physical examination may include atypical clinical presentations, consideration of multiple diagnoses, ruling out a diagnosis, or confirming a clinical suspicion [29]. In taking account of the cost efficiency and managed care reinforced by our national health insur-ance system, it is important to develop clinical guidelines for the use of electrodiagnostic tests in the assessment of CTS in Taiwan.
Using the physician’s clinical diagnosis as the standard criterion, the sensitivity of NCV testing in our study was 74%. This is in line with the findings of Atroshi et al [29] and Finsen and Russwurm [30], who reported sensitivities of 70% and 78%, respectively. On the other hand, sensitivities for Tinel’s sign and Phalen’s test with NCV studies as the criterion in the present study were 91% and 73%,
respec-Table 5. Phalen’s test and nerve conduction velocity (NCV) studies
NCV (+) NCV (–) Sensi-(n = 375) Sensi-(n = 141) tivity Phalen’s test (+) (n = 76) 40 16 72.7% Phalen’s test (–) (n = 26) 15 2
Table 4. Tinel’s sign and nerve conduction velocity (NCV) studies
NCV (+) NCV (–) Sensi-(n = 375) Sensi-(n = 141) tivity Tinel’s sign (+) (n = 311) 188 65 91.3% Tinel’s sign (–) (n = 39) 18 14
tively. The sensitivities and specificities of NCV test-ing and provocative tests in symptomatic patients vary widely in the literature. The reasons behind these large variations may include the population investigated, dif-ferent stages of progression of the syndrome, examination techniques, and differences in case definition [31]. The fact that NCV studies were significantly correlated with Ti-nel’s sign but not with Phalen’s test in the present study ac-corded with the staging of CTS described by Novak et al [32], in that Phalen’s test may be more likely to be most sen-sitive in the early stages of the disease, while Tinel’s sign and electrodiagnosis may be the most sensitive in more ad-vanced stages when focal segmental demyelination through wallerian degeneration progresses to regeneration of fibers. In other words, most of the CTS patients in our study may represent more severe cases of the syndrome.
Two major methodologic limitations of this study re-strict the generalizability of the results. The first issue is the representativeness of our study sample relative to the total CTS patient population throughout Taiwan during the study period. Second, due to the retrospective nature of data collection, some clinical information was not available for all patients. For instance, detailed description of the clinical his-tory was lacking in many medical records, so a thorough analysis of the clinical symptoms could not be obtained.
In conclusion, no gold standard exists for the diagnosis of CTS [33]. Although NCV studies are by far the most objective assessment of nerve function, physicians from all the specialty fields involved in the care of CTS in a busy medical setting had a tendency to determine a diagnosis of CTS by means of clinical history and physical examination. The role of NCV studies seemed to lie in the differential diagnosis of CTS, facilitating appropriate early treatment, and estimation and evaluation of improvement from sur-gery or therapy. Further research is warranted to clarify physicians’ viewpoints on the applicability of NCV testing to the diagnosis of patients with possible CTS.
R
EFERENCES1. Werner R, Armstrong TJ, Bir C, et al. Intracarpal canal pressures: the role of finger, hand, wrist and forearm position.
Clin Biomech (Bristol, Avon) 1997;12:44–51.
2. Occupational Injuries and Illnesses in the United States by Industry. Bureau of Labor Statistics Bulletin 2130. Washington, DC: Government Printing Office, 1982.
3. Atroshi I, Gummesson C, Johnsson R, et al. Prevalence of carpal tunnel syndrome in a general population. JAMA 1999; 282:153–8.
4. Olsen KM, Knudson DV. Change in strength and dexterity after open carpal tunnel release. Int J Sports Med 2001;22: 301–3.
5. King PM. Sensory function assessment. A pilot comparison study of touch pressure threshold with texture and tactile discrimination. J Hand Ther 1997;10:24–8.
6. DeKrom MC, Knipchild PG, Kester AD, et al. Efficacy of provocative tests for diagnosis of carpal tunnel syndrome.
Lancet 1990;335:393–5.
7. Gellman H, Gelberman RH, Tan AM, et al. Carpal tunnel syndrome. An evaluation of the provocative diagnostic tests.
J Bone Joint Surg Am 1986;68:735–7.
8. Mondelli M, Passero S, Giannini F. Provocative tests in different stages of carpal tunnel syndrome. Clin Neurol Neurosurg 2001; 103:178–83.
9. Carroll GJ. Comparison of median and radial nerve sensory latencies in the electrophysiological diagnosis of carpal tunnel syndrome. Electroencephalogr Clin Neurophysiol 1987;68:101–6. 10. De Lean J. Transcarpal median sensory conduction: detection of latent abnormalities in mild carpal tunnel syndrome. Can J
Neurol Sci 1988;15:388–93.
11. Bingham RC, Rosecrance JC, Cook TM. Prevalence of abnormal median nerve conduction in applicants for industrial jobs. Am
J Ind Med 1996;30:355–61.
12. Szabo RM, Madison M. Management of carpal tunnel syndrome. In: Kasdan ML, ed. Occupational Hand and Upper
Extremity Injuries and Diseases. Philadelphia: Hanley & Belfus
Inc, 1991;341–51.
13. Gilliat RW, Sears TA. Sensory nerve action potentials in patients with peripheral nerve lesions. J Neurol Neurosurg Psychiatry 1958;21:109–18.
14. Practice parameter for electrodiagnostic studies in carpal tunnel syndrome: summary statement. American Association of Electrodiagnostic Medicine, American Academy of Neurology, American Academy of Physical Medicine and Rehabilitation. Muscle Nerve 1993;16:1390–1.
15. Haig AJ, Tzeng HM, LeBreck DB. The value of electrodiagnos-tic consultation for patients with upper extremity nerve complaints: a prospective comparison with the history and physical examination. Arch Phys Med Rehabil 1999;80:1273–81. 16. Mondelli M, Giannini F, Vecchierelli B, et al. Diagnostic pathway in carpal tunnel syndrome. Riv Neurobiol 2000;46: 301–5.
17. Phalen GS. The carpal-tunnel syndrome. Seventeen years’ experience in diagnosis and treatment of six hundred fifty-four hands. J Bone Joint Surg Am 1966;48:211–28.
18. Stevens JC. AAEE minimonograph #26: the electrodiagnosis of carpal tunnel syndrome. Muscle Nerve 1987;10:99–113. 19. Duncan KH, Lewis RC Jr, Foreman KA, Nordyke MD.
Treatment of carpal tunnel syndrome by members of the American Society for Surgery of the Hand: results of a questionnaire. J Hand Surg [Am] 1987;12:384–91.
20. Mainous AG 3rd, Nelson KR. How often are preoperative electrodiagnostic studies obtained for carpal tunnel syndrome in a Medicaid population? Muscle Nerve 1996;19:256–7. 21. World Health Organization. International Classification of
Disease, Injuries and Cause of Death, 9th revision. Geneva: World
Health Organization, 1977.
22. Atroshi I, Gummesson C, Johnsson R, et al. Symptoms, disability, and quality of life in patients with carpal tunnel syndrome. J Hand Surg [Am] 1999;24:398–404.
23. Padua L, Padua R, Nazzaro M, Tonali P. Incidence of bilateral symptoms in carpal tunnel syndrome. J Hand Surg [Br] 1998; 23:603–6.
24. Kitsis CK, Savvidou O, Alam A, et al. Carpal tunnel syndrome despite negative neurophysiological studies. Acta Orthop Belg 2002;68:135–40.
25. Jordan R, Carter T, Cummins C. A systematic review of the utility of electrodiagnostic testing in carpal tunnel syndrome.
Br J Gen Pract 2002;52:670–3.
26. Occupational disease surveillance: carpal tunnel syndrome.
MMWR Morb Mortal Wkly Rep 1989;38:485–9.
27. Davis L, Wellman H, Punnett L. Surveillance of work-related carpal tunnel syndrome in Massachusetts, 1992–1997: a report from the Massachusetts Sentinel Event Notification System for Occupational Risks (SENSOR). Am J Ind Med 2001;39:
58–71.
28. Lo JK, Finestone HM, Gilbert K, et al. Community-based re-ferrals for electrodiagnostic studies in patients with possible carpal tunnel syndrome: what is the diagnosis? Arch Phys Med
Rehabil 2002;83:598–603.
29. Atroshi I, Gummesson C, Johnsson R, et al. Diagnostic pro-perties of nerve conduction tests in population-based carpal tunnel syndrome. BMC Musculoskelet Disord 2003;4:9–30. 30. Finsen V, Russwurm H. Neurophysiology not required before
surgery for typical carpal tunnel syndrome. J Hand Surg [Br] 2001;26:61–4.
31. Szabo RM, Slater RR Jr, Farver TB, et al. The value of diagnostic testing in carpal tunnel syndrome. J Hand Surg [Am] 1999;24: 704–14.
32. Novak CB, Mackinnon SE, Brownlee R, et al. Provocative sensory testing in carpal tunnel syndrome. J Hand Surg [Br] 1992;17:204–8.
33. Rempel D, Evanoff B, Amadio PC, et al. Consensus criteria for the classification of carpal tunnel syndrome in epidemiologic studies. Am J Public Health 1998;88:1447–51.
!"VO==NN==T= !"VP==N==S= !"#$%&'() !"!= !"#$%& !"#$%&'=NMM
!"#$%"&'()*+,
!"#$%
N= O= !P= O= O= Q !"!= !"#N= O= !"#$%&Q !"#$#%= !"#P !"#$%&'()*+,-./0!"#123456 !"#,*+ !"#$%&'()*+,,-./0123456789:4;<=>?@ !"#$%&"'()*+,-./0123456789+:&;<= !"#$%"&'()*+,-./012"34/56789:;<="> OMMN =OMMO= !"#$% NIMRM !"#$%&'()*+, ! SOO= !"#$%&'()*+,-./0123456789: !"#$%&'()*+,-./012!34+PQKVB= !"#$ !"#$%&'()*+,-./0=qáåÉä==mÜ~äÉå= !"#$=UKTB !"#$%&'()*+,-=qáåÉä==mÜ~äÉå= !"#$%&RRB= !"#$%&'()*+,-./=qáåÉä==mÜ~äÉå= !"#$%&'( OTKPB= !"#$%&'()*+,-./01234567)89:; !"#$%&'=NKS= !"#$%&'()*+"#,-./0=ERNS F !=qáåÉä==EPRM F==mÜ~äÉå==ENMO F = !"#$%&' !"#$%&'(%)"*+,-./0%1234-./56789:;<!"#$%&'()*+,- !!"#$%&'()*+,- !"#$mÜ~äÉå=!"#$%&'()*+,- qáåÉä=!"#$%&'()*+,- !"#$%& !"=OMMQXOMWNMSJNQ
