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Current Practice in the Use of Nerve Conduction Studies in Carpal Tunnel Syndrome by Surgeons in the NetherlandsFrom the Department of Neurology and Neurophysiology, Canisius-Wilhelmina Hospital, Nijmegen, The Netherlands Correspondence: Franka Claes MD, Canisius–Wilhelmina Hospital, Department of Neurology and Neurophysiology, P.O. Box 9015, 6500 GS Nijmegen The Netherlands. Tel.: +31 24 3658765; fax: +31 24 3657329. E-mail:f.claes{at}cwz.nl
The current practice in and the opinion about the treatment of carpal tunnel syndrome by surgeons in the Netherlands was evaluated in respect of the extent to which electrodiagnostic studies are used or needed to confirm the diagnosis. Questionnaires were sent to all Dutch surgeons who operate on patients with carpal tunnel syndrome. The response rate was 47% (324 out of 686). The majority of neurosurgeons and orthopaedic surgeons seldom operate without electrodiagnostic confirmation in line with the Dutch consensus guideline on this subject. In contrast, plastic surgeons operate more often on patients with clinically defined carpal tunnel syndrome even with normal electrodiagnostic studies. Knowledge of these strikingly different diagnostic and therapeutic strategies and opinions may influence diagnostic and referral behaviour of clinical neurologists and others.
Key Words: carpal tunnel syndrome • surgery • questionnaire Carpal tunnel syndrome (CTS) causing compression of the median nerve within the carpal tunnel is the most common entrapment neuropathy. The clinical diagnosis is based on a history of pain, paraesthesiae and numbness in the palmar surfaces and tips of the fingers innervated by the median nerve. Various clinical tests are available to help make a diagnosis. However, these are not very specific (D’Arcy and McGee, 2000; De Krom et al., 1990; Massy-Westropp et al., 2000; Rempel et al., 1998). Unfortunately, a gold standard for the diagnosis CTS does not exist and, often, electrodiagnostic studies are performed to help confirm the diagnosis. However, there exists a significant body of patients with typical complaints of CTS, in whom electrodiagnostic studies are negative. In the second literature review published by the American Association of Electrodiagnostic Medicine (Jablecki et al., 2002), it was concluded that median sensory and motor nerve conduction studies confirm a clinical diagnosis of CTS with a sensitivity of more than 85%. This identifies that the tests are not absolute in allowing a diagnosis of this condition to be made. In the Netherlands, patients with CTS complaints are often seen initially by a neurologist. When CTS is diagnosed, both clinically and electrodiagnostically, and an operation is indicated, the neurologist refers the patient to a surgeon. In general, CTS surgery is performed by neurosurgeons, orthopaedic surgeons and plastic surgeons. In addition, an undetermined number of CTS patients are referred to a surgeon directly by their general practitioner. Recently, the Dutch Institute for Healthcare Improvement (2006) (CBO), published a consensus guideline on treatment of CTS (CBO guideline, 2006). The Dutch Associations of Neurology, Surgery, Plastic Surgery and Neurosurgery all participated in the development of this guideline. In this consensus guideline, the advice was to perform an open release of the carpal tunnel only when electrodiagnostic tests have confirmed the clinical diagnosis of CTS. When electrodiagnostic studies are normal, conservative treatment was recommended. With the controversies existing about the need for electrodiagnostic studies confirming the diagnosis of CTS, it would be interesting to know the opinion of surgeons operating on patients with CTS. The objective of this study was to evaluate the opinion of different surgical disciplines in regard of the need for electrodiagnostic testing for confirmation of the diagnosis CTS and to what extent patients with clinically defined CTS without electrodiagnostic confirmation are still operated on.
To evaluate the current practice in planning surgical treatment of clinically defined CTS by surgeons, with or without the use of electrodiagnostic studies to confirm the diagnosis, a questionnaire (Table 1) was sent to neurosurgeons, orthopaedic surgeons and plastic surgeons in the Netherlands. The surgical departments of all hospitals in the Netherlands were targeted. A stamped and addressed return envelope was included. Eventually, 686 surgeons received the questionnaire personally. Among them were 110 neurosurgeons, 417 orthopaedic surgeons and 159 plastic surgeons.
The questionnaire assessed the number of patients tested electrodiagnostically and the number of patients on whom surgery for CTS was carried out by the surgeons, or residents supervised by them. The next questions assessed the likelihood one would operate on CTS patients in different possible subsets. In general, carpal tunnel release in the Netherlands is performed most frequently by neurosurgeons, followed by plastic surgeons and orthopaedic surgeons. Most orthopaedic surgeons are general orthopaedic surgeons, operating also on CTS patients.
Three hundred and twenty-four of 686 questionnaires were returned, which is a response rate of 47%. We chose to send questionnaires anonymously, with the regrettable consequence of not being able to send a reminder letter to increase the response rate. Among the responders there were 62 of 110 neurosurgeons (56%), 165 of 417 orthopaedic surgeons (40%) and 97 of 159 plastic surgeons (61%). Thirty-seven surgeons returned an incomplete questionnaire, because they did not operate on patients with CTS. Of these, 30 were orthopaedic surgeons. These questionnaires were not included in the analysis. Thirty-one percent of neurosurgeons stated they operated on 150 or more patients a year, or this number of patients were being operated on under their supervision. For orthopaedic surgeons and plastic surgeons these percentages were 7 and 15, respectively. In the whole group, 64% of surgeons stated that 96% to 100% of their patients with complaints suggestive of CTS underwent electrodiagnostic studies. For neurosurgeons, orthopaedic surgeons and plastic surgeons, these percentages were 90%, 68% and 39%, respectively. One surgeon did not answer this question. Fifty-seven percent of all surgeons seldom, or never, operated on patients with clinically definite CTS, normal electrodiagnostic studies and failing conservative treatment. For neurosurgeons, orthopaedic surgeons and plastic surgeons these percentages were 61%, 81% and 14%, respectively. All surgeons answered this question. Fifty-five percent of all surgeons seldom, or never, operated on patients with clinically definite CTS, normal electrodiagnostic studies and only temporary relief of symptoms from corticosteroid injection(s). For neurosurgeons, orthopaedic surgeons and plastic surgeons, these percentages were 53%, 72% and 27%, respectively. All surgeons answered this question. Eighty percent of all surgeons seldom, or never, operated on patients with a clear history of CTS without confirmation of the diagnosis by electrodiagnostic studies. For neurosurgeons, orthopaedic surgeons and plastic surgeons, this percentage was 92%, 88% and 59%, respectively. Twenty-five surgeons (8%) did not answer this question. A complete overview of the results is given in Table 2.
In the literature, opinions differ about the need for electrodiagnostic confirmation of CTS. In a study by Finsen and Russwurm (2001), 68 patients with typical CTS underwent open carpal tunnel release. They all underwent electrodiagnostic studies, but these were not assessed until the end of the study. Sixty-three of the 68 patients responded well to surgery, 14 of these had normal electrodiagnostic studies. These authors concluded that electrodiagnostic studies contributed little to the diagnosis in typical cases of CTS and might confound more than help. Other studies suggest that electrodiagnostic studies may have an important role in predicting the outcome of surgical decompression, disclosing other pathologies, particularly in atypical cases, and providing a useful baseline if patients do not improve after surgery (Padua et al., 1996, 1997). Electrodiagnostic studies can be of value in selecting patients for a specific treatment and in assessing efficacy of treatment. However, this is only reliable if there is a correlation between electrodiagnostic studies and outcome of treatment. Several studies addressed this issue (Longstaff et al., 2001; Schrijver et al., 2005). They found no, or only modest, correlation between electrodiagnostic studies and clinical outcome after surgery. Some patients with complete relief of symptoms after surgery still had abnormal electrodiagnostic studies, while others with ongoing symptoms had normalised results. Since patients with CTS complaints are operated on by different surgical disciplines, it is interesting to know the opinion of these surgeons regarding this issue. Ebskov et al. (1997) found that most surgeons in Denmark use pre-operative electrodiagnostic studies in less than 50% of cases. However, neurosurgeons in Denmark nearly always used electrodiagnostic studies. Duncan et al. (1987) reported that 37.9% of members of the American Society for Surgery of the Hand always used electrodiagnostic studies, 26.3% often used them and 33.2% sometimes used them. They also found that surgeons practicing in areas in which medical malpractice suits are common were much more likely to obtain electrodiagnostic studies. Storm et al. (2005) reported that 20% of 1567 patients undergoing carpal tunnel release in Washington State in 1999 did not have an electrodiagnostic examination before surgery. People living in rural areas seemed particularly likely to have no, or inadequate, electrodiagnostic studies. Witt et al. (2004) pointed out that electrodiagnostic studies provide independent information on the evaluation of suspected CTS, not fully predictable from clinical variables alone. Controversy persists, however, about the necessity of electrodiagnostic studies (Smith, 2002). Recently, Graham et al. (2006) developed and validated clinical diagnostic criteria for CTS, which correlated well with judgements of a panel of experts on CTS. These criteria can be used to decide on possible treatment. Expanding access to electrodiagnostic studies can be a way to increase performance of electrodiagnostic studies in patients with CTS complaints. A retrospective analysis by Megerian et al. (2007) showed that point-of-service nerve conduction studies by family medicine, primary care and internal medicine physicians without specific neurophysiologic training for CTS was performed in accordance with evidence based testing parameters. CTS was identified in 53.1% of tested limbs, while the study was normal in 30.5%. This finding is interesting. However, prospective studies, with comparison to nerve conduction studies performed by specialists with specific neurophysiological training, are needed. In the Netherlands, the majority of neurosurgeons and orthopaedic surgeons seldom, or never, operate on patients without electrodiagnostic confirmation. This is in line with the advice in the Dutch consensus paper mentioned earlier (CBO guideline, 2006). This reluctance to operate is less when patients have had temporary relief of CTS complaints after locally injected corticosteroids, even if the electrodiagnostic studies were negative. In contrast, plastic surgeons are more likely to operate on patients with clinically defined CTS and normal electrodiagnostic studies under the various circumstances described in the circulated questionnaire, although this was far from a universal finding among all plastic surgeons. There may be local reasons for the particular views of different groups of surgeons in the Netherlands. In this country, plastic surgeons are particularly experienced in hand surgery, which may be a reason for the relatively low threshold in this group to performing operations in the face of clinically defined CTS without electrodiagnostic confirmation. Also, electromyography and nerve conduction studies are performed by neurologists and most Dutch clinical neurologists, who are a major referring source of these patients, find electrodiagnostic testing in CTS desirable. However, they also perform nerve conduction studies directly requested by surgeons. Furthermore, one year of clinical neurology is an obligatory part of the clinical training of neurosurgeons in the Netherlands. This might be an explanation for the higher percentage of neurosurgeons performing CTS operations only in cases with electrodiagnostic confirmation. Orthopaedic surgeons seem to be most conservative regarding surgery in CTS patients with negative electrodiagnostic studies: this may be related to the fact that they have no training in neurology and clinical neurophysiology and, probably, rely on the expertise and advice of the neurologists. Whether a patient with clinically defined CTS without electrodiagnostic abnormalities undergoes surgery is likely to depend on the surgical discipline to which he or she is referred. Consequently, a clinical neurologist may in fact determine the treatment strategy in the Netherlands. This, in addition, may seriously affect the results presented in papers on the treatment of CTS as a result of referral bias. Although not common practice in the Netherlands, fear of litigation can also play a role in deciding to follow the advice of a national guideline, possibly occurring more frequently among orthopaedic surgeons because of lack of neurological and neurophysiological background. This study has limitations. As most other surveys, this survey was prone to response bias. It is likely that there are more surgeons who do not perform CTS surgery among the non-responders. Because the questionnaires were sent anonymously, we were not able to find out possible reasons for not responding. For the same reason, it was impossible to send a reminder letter to increase response rate. We did not perform formal statistical testing of the data, because of the clearly visible differences between the data. Over the last few years, ultrasonography of peripheral nerves has improved enormously (Kele et al., 2003; Nackamichi and Tachibana, 2002) and a significant number of patients with CTS have been reported to have an increased diameter of the median nerve in the carpal tunnel, ultrasonographically. In patients with clinically defined CTS and normal electrodiagnostic studies, the diagnostic value of ultrasonography needs to be defined, as this may provide a resolution to this dilemma.
Manuscript received November 28, 2006. Accepted for publication August 27, 2007.
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Journal of Hand Surgery (European Volume), Vol. 32, No. 6,
663-667 (2007) This article has been cited by other articles:
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Abstract
MATERIALS AND METHODS
