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Electrical studies as a prognostic factor in the surgical treatment of carpal tunnel syndrome
Letters to the Editor
Electrical Studies as a Prognostic Factor in the Surgical Treatment of Carpal Tunnel Syndrome To the Editor: We have been concerned about the apparent messages expressed in the recently published article by Braun and Jackson, "Electrical Studies as a Prognostic Factor in the Surgical Treatment of Carpal Tunnel Syndrome" (J Hand Surg 1994; 19A:893-900). The authors discredited preoperative electrodiagnostic (EDX) studies in all patients with their exclusive diagnosis of carpal tunnel syndrome (CTS) and obtained excellent results in all their carpal tunnel patients, especially by virtue of the fact that all their patients, having undergone carpal tunnel release, returned to work within the same time period. Apparently, it was the same work that produced the carpal tunnel symptoms initially. The thrust of their conclusion is that EDX results did not provide significant data for prediction of functional recovery or re-employment after carpal tunnel release in a group of patients with workrelated CTS. Reported were 151 patients who used their hands repetitively in their jobs. In 50% of cases selected for carpal tunnel open surgery over a 5-year period, there were no preoperative electrical studies, no clinical criteria were listed for the diagnosis of CTS, no preexisting factors were enumerated, and no coexisting diagnoses were listed. Theoretically, one half of the patients undergoing carpal tunnel release might not have had CTS as the diagnosis. Neurologic symptoms of CTS can mimic many other conditions in the upper extremity, including cervical radiculopathy I and myelopathy, metabolic neuropathies, amyotrophic lateral sclerosis, brachial plexus disease, and compression, to name just a few. Hand surgeons, orthopaedic surgeons, and neurologists all have had occasion to make the diagnosis of CTS, only to discover after re-examination or EDX study that their clinical impression was incorrect and that another condition was responsible for the symptoms mimicking CTS. 518
The Journal of Hand Surgery
There are probably two large groups of patients within the work force who are worthy of mention in the differential diagnosis and probably constitute the bulk of patients who present with symptoms similar to those of CTS but are found to have a different diagnosis after careful evaluation. One group of patients presents with paresthesias in the hand, either in the median or ulnar territory and more often at night than during the day, with occasional pain and clumsiness during the symptoms. This is a group who frequently have negative EDX study for CTS and who, after careful examination, demonstrate positive findings compatible with thoracic outlet syndromeY Yet another large number of patients (becoming even larger as the condition is more recognized) are the group with repetitive strain injury (RSI)? Keisler and Finholt 5 have discussed repetitive strain injury as an extreme illustration of how the social context of work and technical changes define and influence the nature of health problems. This is a growing problem, which has received a great deal of academic interest, 6 with simultaneous discussion by lay people evidenced by multiple articles in city and regional newspapers as well as Time magazine2 Arons and Frost (personal communication) have analyzed over 50 referred cases of CTS in young women performing repetitive tasks and found that 40% were indeed overuse syndromes including CTS, 40% were cases of repetitive strain injury not amenable to surgery and all negative on EOX studies, and in 20% of the cases the symptoms were thought to have emotional causes. This unpublished information was presented recently in a series of lectures to insurance carriers in Connecticut. It would appear that from time to time we need to be reminded of some opinions that govern good practice. In an editorial published in The Journal of Hand Surgery, 8 the opinion was expressed that all patients suspected of having CTS should have EDX studies to (1) establish a quantitative baseline; (2) detect a coexisting unsuspected polyneuropathy; and (3) show that a diagnosis of CTS regarded as likely but uncertain is indeed correct. In a more recent article, 9
The Journal of Hand Surgery / Voi. 21A No. 3 May I 990
it was stated not only that nerve conduction studies are an indispensable part of preoperative evaluation, but that it is unjustified to intervene surgically for CTS without them. Katz et aU ~ reported that EDX conduction studies are the method of choice for eonfirming the diagnosis of CTS. In a special summary statement by the American Academy of Neurology, American Association of Electrodiagnostic Medicine. and American Academy of Physical Medicine and Rehabilitation, '~ the results of EDX studies were claimed to be highly sensitive and specific for the diagnosis of CTS, with a specificity of 95% or greater. The variability in reported sensitivity of EDX studies u ranged from 49% to 84% and was probably related to training o f the electromyographer and the choice of the particular test to establish the diagnosis of e T a . 12 While the electromyographer is not expected to establish a different diagnosis when applicable, it is our personal opinion that the eiectromyographer should be able to raise the question of differential diagnosis to aid in the management of the patient. Grundberg ~3found only an 8% false negative rate and Louis and Hankin *~noted only a 12% false negative EDX rate, especially in young women undergoing electronegative carpal tunnel release in workers' compensation cases. Approximately 60% of patients referred with the diagnosis of CTS actually have received this diagnosis on the basis of EDX studies criteria (M. Hasbani and S. Bridgers, personal communication). This is similar to the percentage cited by Buch-Jaeger and Foucher.9 It is also interesting that in Brown and Jackson's study, 75 of 125 patients undergoing EDX studies were found to have a positive test for CTS. This constitutes 60% of the patients tested. This information, along with the well-known fact that symptoms of CTS may be due to other conditions in the upper extremity mimicking CTS, raises a serious question as to whether the 40% who tested negative for CTS in EDX studies by Braun and Jackson may indeed have carried this diagnosis and therefore raises the additional question as to whether and when surgical intervention should be made in this group of patients. A prospective study should include a group of patients who would undergo further conservative management for 4 months (ie, one group of patients having positive EDX studies for CTS), along with another group having negative studies for CTS undergoing surgery as in this article, and yet another group of patients having negative EDX studies being
519
treated conservatively for another 4 months after the initial 3 1/2 months of observation as in the other two groups. Our personal prediction from our own experience is that a large number probably would have returned to some form of work without the need of surgery. Concerning the results of CTS, a rapid review of several references reveals that surgical intervention for CTS is not as perfect as Dr. Brown would like us to believe, in 1984, A1-Qualtan et al. '' reported a poor outcome in 13.5% of their carpal tunnel surgery patients. In a survey of current treatment of CTS, based on 26,000 cases (Shenck RR, presented at the 1987 annual meeting of the American Association for Hand Surgery, unpublished data), 50% of hands were asymptomatic following surgery, 33% markedly improved, 5% slightly improved, and 3% unimproved. In 1992 Yu et al. '6 determined carpal tunnel surgery results as follows: good 27%, fair 42%, poor 32%. This was for patients who had associated symptoms of thoracic outlet syndrome or had performed strenuous physical work and all of whom had failed conservative treatment. In 1993 Hauft et al? 7 reported only an 86% improvement in all their postoperative CTS cases, and all their patients had preoperative ETX studies. Our message is different from the clinical message of Braun and Jackson. Readers, residents, and tellows, in our personal opinion, should be discouraged initially from suggesting operative intervention for electronegative CTS. Electronegative CTS patients should undergo release only after sustained periods of search for a different etiology of their symptoms and only after a considerable period of conservative treatment. Kaplan et al. TM noted that their nonsurgical management of CTS was successful in over 18% of their patients and partially successful in almost 35%. They succinctly stated: "Because carpal tunnel syndrome encompasses all causes and stages of median nerve compression at the wrist, there is no uniform presentation; instead, there is a variety of symptoms ranging from occupational paresthesiae to complete lack of motor and sensory function." We would be remiss not to quote Novak et a1.19: "Despite advances in electrophysiology, the diagnosis of carpal tunnel syndrome remains a clinical one. No single test is currently used as the gold standard, though electrodiagnostic studies and nerve conduction studies are frequently performed. However, these relate directly to the abnormal physiology of the median nerve in the carpal tunnel and, in the early
520
Lettersto the Editor
stages of carpal tunnel syndrome, m a y fail to detect any abnormality." Nevertheless, also published in The Journal of Hand Surgery was the article by Luchetti et al., 2~ who found that stepwise measurement o f median nerve sensory conduction velocity was the most sensitive method of diagnosing the early stage of CTS. Realistically, we are not discounting the cost of E D X testing. However, this should be weighed against the cost of unnecessary surgery and the cost of the complication rate of carpal tunnel surgery. One severe complication of carpal tunnel surgery m a y equal the cost of over 100 E D X studies without taking into account the pain and suffering and further time loss from work. Furthermore, we must b e c o m e accustomed to the fact that s o m e patients will need to change their jobs that produced CTS and without undergoing surgery rather than to undergo the surgery with the hope of preventing recurrent symptoms. Surgeons are trained to operate and generally are not trained to be conservative. M a n a g e d care insurance and algorithmic medicine will soon be the deciding factor in any case.
Marvin S. Arons, MD Moshe Hasbani, MD Section of Plastic Surgery Hospital of St. Raphael 1450 Chapel Street New Haven, CT 06511
References 1. Hong C-Z, Soon Hae L, Lum R Cervical radiculopathy: clinical, radiographic and EMG findings. Orthop Rev 1986;15:31-34. 2. Novak CB, MacKinnon SE, Patterson GA. Evaluation of patients with thoracic outlet syndrome. J Hand Surg 1993;18A:292-299. 3. Moore WS, Machleder HI, Porter JM, Roos DB. Symposium: thoracic outlet syndrome. Contemp Surg 1994;45:99-111. 4. Ireland DCR. Review article psychological and physical aspects of occupational arm pain. J Hand Surg 1988; 13B:5-9. 5. Kiesler S, Finholt T. Mystery of RSI. Am Psychol 1988; 43:1004-1015. 6. MacKinnon SE, Novak CB. Clinical commentary: pathogenesis of cumulative trauma disorder. J Hand Surg 1994;19A:873-881. 7. Elmer-Dewitt P. A royal pain in the wrist. Time Magazine October 24, 1994:60-61.
8. Payan J. Editorial. The carpal tunnel syndrome: can we do better? J Hand Surg 1988;13B:365-367. 9. Buch-Jaeger N, Foucher G. Correlation of clinical signs with nerve conduction tests in the diagnosis of carpal tunnel syndrome. J Hand Surg 1994;19B:720-724. 10. Katz JN, Larsen MG, Fossel AH, Laing MH. Validation of a surveillance case definition of carpal tunnel syndrome. Am J Public Health 1991;81:189-193. 11. American Academy of Neurology, American Association of Electrodiagnostic Medicine, and American Academy of Physical Medicine and Rehabilitation. Practice parameters for electrodiagnostic studies in carpal tunnel syndrome (summary statement). Neurology 1993;43:2404-2405. 12. Seror R Sensitivity of the various tests for the diagnosis of carpal tunnel syndrome. J Hand Surg 1994;19B:725-728. 13. Gmndberg AB. Carpal tunnel decompression in spite of normal electromyography. J Hand Surg 1983;8:348-349. 14. Louis DS, Hankin FM. Symptomatic relief following carpal tunnel decompression with normal electroneurodiagnostic studies. Orthopedics 1987;10:434~436. 15. A1-Qualtan MM, Bowen V, Manktelow RT. Factors associated with poor outcome and primary carpal tunnel release in non-diabetic patients. J Hand Surg 1994;19B: 622-625. 16. Yu G-Z, Firrell JC, Tsai T-M. Preoperative factors in treatment outcomes following carpal tunnel release. J Hand Surg 1992; 17B :646-650. 17. Haupt WF, Sintzer G, Schop A, Lottgin J, Powlik G. Longterm results of carpal tunnel decompression. J Hand Surg 1993;18B:471-474. 18. Kaplan SJ, Glickel SZ, Eaton RG. Predictive factors in the nonsurgical treatment of carpal tunnel syndrome. J Hand Surg 1990; 15B: 106-108. 19. Novak CB, MacKinnon SE, Brownlee R, Kelly L. Provocative sensory testing in carpal tunnel syndrome. J Hand Surg 1992; 17B :204-208. 20. Luchetti R, Schoenhuber R, Alfarano M, Montagna G, Pederzini L, Soragni O. Neurophysiological assessment of the early phases of carpal tunnel syndrome with the inching technique before and during operation. J Hand Surg 1991;16B:415-419.
In Reply: A 7-page letter with 20 references can hardly be ignored. I am impressed and will add the references to m y library list. The article that was written summarizes our clinical experience, no more and no less. Our cases clearly indicate that threshold E D X studies in our c o m m u n i t y do not offer help in determining prognosis for patients who were operated on for CTS. We purposely avoided possible reasons for this situation. The obvious reason is that we are extremely careful in selecting patients who undergo carpal tunnel release if their E D X findings are not abnormal. We do not operate on patients as a diagnostic procedure.
Electrical Studies as a Prognostic Factor in the Surgical Treatment of Carpal Tunnel Syndrome To the Editor: We have been concerned about the apparent messages expressed in the recently published article by Braun and Jackson, "Electrical Studies as a Prognostic Factor in the Surgical Treatment of Carpal Tunnel Syndrome" (J Hand Surg 1994; 19A:893-900). The authors discredited preoperative electrodiagnostic (EDX) studies in all patients with their exclusive diagnosis of carpal tunnel syndrome (CTS) and obtained excellent results in all their carpal tunnel patients, especially by virtue of the fact that all their patients, having undergone carpal tunnel release, returned to work within the same time period. Apparently, it was the same work that produced the carpal tunnel symptoms initially. The thrust of their conclusion is that EDX results did not provide significant data for prediction of functional recovery or re-employment after carpal tunnel release in a group of patients with workrelated CTS. Reported were 151 patients who used their hands repetitively in their jobs. In 50% of cases selected for carpal tunnel open surgery over a 5-year period, there were no preoperative electrical studies, no clinical criteria were listed for the diagnosis of CTS, no preexisting factors were enumerated, and no coexisting diagnoses were listed. Theoretically, one half of the patients undergoing carpal tunnel release might not have had CTS as the diagnosis. Neurologic symptoms of CTS can mimic many other conditions in the upper extremity, including cervical radiculopathy I and myelopathy, metabolic neuropathies, amyotrophic lateral sclerosis, brachial plexus disease, and compression, to name just a few. Hand surgeons, orthopaedic surgeons, and neurologists all have had occasion to make the diagnosis of CTS, only to discover after re-examination or EDX study that their clinical impression was incorrect and that another condition was responsible for the symptoms mimicking CTS. 518
The Journal of Hand Surgery
There are probably two large groups of patients within the work force who are worthy of mention in the differential diagnosis and probably constitute the bulk of patients who present with symptoms similar to those of CTS but are found to have a different diagnosis after careful evaluation. One group of patients presents with paresthesias in the hand, either in the median or ulnar territory and more often at night than during the day, with occasional pain and clumsiness during the symptoms. This is a group who frequently have negative EDX study for CTS and who, after careful examination, demonstrate positive findings compatible with thoracic outlet syndromeY Yet another large number of patients (becoming even larger as the condition is more recognized) are the group with repetitive strain injury (RSI)? Keisler and Finholt 5 have discussed repetitive strain injury as an extreme illustration of how the social context of work and technical changes define and influence the nature of health problems. This is a growing problem, which has received a great deal of academic interest, 6 with simultaneous discussion by lay people evidenced by multiple articles in city and regional newspapers as well as Time magazine2 Arons and Frost (personal communication) have analyzed over 50 referred cases of CTS in young women performing repetitive tasks and found that 40% were indeed overuse syndromes including CTS, 40% were cases of repetitive strain injury not amenable to surgery and all negative on EOX studies, and in 20% of the cases the symptoms were thought to have emotional causes. This unpublished information was presented recently in a series of lectures to insurance carriers in Connecticut. It would appear that from time to time we need to be reminded of some opinions that govern good practice. In an editorial published in The Journal of Hand Surgery, 8 the opinion was expressed that all patients suspected of having CTS should have EDX studies to (1) establish a quantitative baseline; (2) detect a coexisting unsuspected polyneuropathy; and (3) show that a diagnosis of CTS regarded as likely but uncertain is indeed correct. In a more recent article, 9
The Journal of Hand Surgery / Voi. 21A No. 3 May I 990
it was stated not only that nerve conduction studies are an indispensable part of preoperative evaluation, but that it is unjustified to intervene surgically for CTS without them. Katz et aU ~ reported that EDX conduction studies are the method of choice for eonfirming the diagnosis of CTS. In a special summary statement by the American Academy of Neurology, American Association of Electrodiagnostic Medicine. and American Academy of Physical Medicine and Rehabilitation, '~ the results of EDX studies were claimed to be highly sensitive and specific for the diagnosis of CTS, with a specificity of 95% or greater. The variability in reported sensitivity of EDX studies u ranged from 49% to 84% and was probably related to training o f the electromyographer and the choice of the particular test to establish the diagnosis of e T a . 12 While the electromyographer is not expected to establish a different diagnosis when applicable, it is our personal opinion that the eiectromyographer should be able to raise the question of differential diagnosis to aid in the management of the patient. Grundberg ~3found only an 8% false negative rate and Louis and Hankin *~noted only a 12% false negative EDX rate, especially in young women undergoing electronegative carpal tunnel release in workers' compensation cases. Approximately 60% of patients referred with the diagnosis of CTS actually have received this diagnosis on the basis of EDX studies criteria (M. Hasbani and S. Bridgers, personal communication). This is similar to the percentage cited by Buch-Jaeger and Foucher.9 It is also interesting that in Brown and Jackson's study, 75 of 125 patients undergoing EDX studies were found to have a positive test for CTS. This constitutes 60% of the patients tested. This information, along with the well-known fact that symptoms of CTS may be due to other conditions in the upper extremity mimicking CTS, raises a serious question as to whether the 40% who tested negative for CTS in EDX studies by Braun and Jackson may indeed have carried this diagnosis and therefore raises the additional question as to whether and when surgical intervention should be made in this group of patients. A prospective study should include a group of patients who would undergo further conservative management for 4 months (ie, one group of patients having positive EDX studies for CTS), along with another group having negative studies for CTS undergoing surgery as in this article, and yet another group of patients having negative EDX studies being
519
treated conservatively for another 4 months after the initial 3 1/2 months of observation as in the other two groups. Our personal prediction from our own experience is that a large number probably would have returned to some form of work without the need of surgery. Concerning the results of CTS, a rapid review of several references reveals that surgical intervention for CTS is not as perfect as Dr. Brown would like us to believe, in 1984, A1-Qualtan et al. '' reported a poor outcome in 13.5% of their carpal tunnel surgery patients. In a survey of current treatment of CTS, based on 26,000 cases (Shenck RR, presented at the 1987 annual meeting of the American Association for Hand Surgery, unpublished data), 50% of hands were asymptomatic following surgery, 33% markedly improved, 5% slightly improved, and 3% unimproved. In 1992 Yu et al. '6 determined carpal tunnel surgery results as follows: good 27%, fair 42%, poor 32%. This was for patients who had associated symptoms of thoracic outlet syndrome or had performed strenuous physical work and all of whom had failed conservative treatment. In 1993 Hauft et al? 7 reported only an 86% improvement in all their postoperative CTS cases, and all their patients had preoperative ETX studies. Our message is different from the clinical message of Braun and Jackson. Readers, residents, and tellows, in our personal opinion, should be discouraged initially from suggesting operative intervention for electronegative CTS. Electronegative CTS patients should undergo release only after sustained periods of search for a different etiology of their symptoms and only after a considerable period of conservative treatment. Kaplan et al. TM noted that their nonsurgical management of CTS was successful in over 18% of their patients and partially successful in almost 35%. They succinctly stated: "Because carpal tunnel syndrome encompasses all causes and stages of median nerve compression at the wrist, there is no uniform presentation; instead, there is a variety of symptoms ranging from occupational paresthesiae to complete lack of motor and sensory function." We would be remiss not to quote Novak et a1.19: "Despite advances in electrophysiology, the diagnosis of carpal tunnel syndrome remains a clinical one. No single test is currently used as the gold standard, though electrodiagnostic studies and nerve conduction studies are frequently performed. However, these relate directly to the abnormal physiology of the median nerve in the carpal tunnel and, in the early
520
Lettersto the Editor
stages of carpal tunnel syndrome, m a y fail to detect any abnormality." Nevertheless, also published in The Journal of Hand Surgery was the article by Luchetti et al., 2~ who found that stepwise measurement o f median nerve sensory conduction velocity was the most sensitive method of diagnosing the early stage of CTS. Realistically, we are not discounting the cost of E D X testing. However, this should be weighed against the cost of unnecessary surgery and the cost of the complication rate of carpal tunnel surgery. One severe complication of carpal tunnel surgery m a y equal the cost of over 100 E D X studies without taking into account the pain and suffering and further time loss from work. Furthermore, we must b e c o m e accustomed to the fact that s o m e patients will need to change their jobs that produced CTS and without undergoing surgery rather than to undergo the surgery with the hope of preventing recurrent symptoms. Surgeons are trained to operate and generally are not trained to be conservative. M a n a g e d care insurance and algorithmic medicine will soon be the deciding factor in any case.
Marvin S. Arons, MD Moshe Hasbani, MD Section of Plastic Surgery Hospital of St. Raphael 1450 Chapel Street New Haven, CT 06511
References 1. Hong C-Z, Soon Hae L, Lum R Cervical radiculopathy: clinical, radiographic and EMG findings. Orthop Rev 1986;15:31-34. 2. Novak CB, MacKinnon SE, Patterson GA. Evaluation of patients with thoracic outlet syndrome. J Hand Surg 1993;18A:292-299. 3. Moore WS, Machleder HI, Porter JM, Roos DB. Symposium: thoracic outlet syndrome. Contemp Surg 1994;45:99-111. 4. Ireland DCR. Review article psychological and physical aspects of occupational arm pain. J Hand Surg 1988; 13B:5-9. 5. Kiesler S, Finholt T. Mystery of RSI. Am Psychol 1988; 43:1004-1015. 6. MacKinnon SE, Novak CB. Clinical commentary: pathogenesis of cumulative trauma disorder. J Hand Surg 1994;19A:873-881. 7. Elmer-Dewitt P. A royal pain in the wrist. Time Magazine October 24, 1994:60-61.
8. Payan J. Editorial. The carpal tunnel syndrome: can we do better? J Hand Surg 1988;13B:365-367. 9. Buch-Jaeger N, Foucher G. Correlation of clinical signs with nerve conduction tests in the diagnosis of carpal tunnel syndrome. J Hand Surg 1994;19B:720-724. 10. Katz JN, Larsen MG, Fossel AH, Laing MH. Validation of a surveillance case definition of carpal tunnel syndrome. Am J Public Health 1991;81:189-193. 11. American Academy of Neurology, American Association of Electrodiagnostic Medicine, and American Academy of Physical Medicine and Rehabilitation. Practice parameters for electrodiagnostic studies in carpal tunnel syndrome (summary statement). Neurology 1993;43:2404-2405. 12. Seror R Sensitivity of the various tests for the diagnosis of carpal tunnel syndrome. J Hand Surg 1994;19B:725-728. 13. Gmndberg AB. Carpal tunnel decompression in spite of normal electromyography. J Hand Surg 1983;8:348-349. 14. Louis DS, Hankin FM. Symptomatic relief following carpal tunnel decompression with normal electroneurodiagnostic studies. Orthopedics 1987;10:434~436. 15. A1-Qualtan MM, Bowen V, Manktelow RT. Factors associated with poor outcome and primary carpal tunnel release in non-diabetic patients. J Hand Surg 1994;19B: 622-625. 16. Yu G-Z, Firrell JC, Tsai T-M. Preoperative factors in treatment outcomes following carpal tunnel release. J Hand Surg 1992; 17B :646-650. 17. Haupt WF, Sintzer G, Schop A, Lottgin J, Powlik G. Longterm results of carpal tunnel decompression. J Hand Surg 1993;18B:471-474. 18. Kaplan SJ, Glickel SZ, Eaton RG. Predictive factors in the nonsurgical treatment of carpal tunnel syndrome. J Hand Surg 1990; 15B: 106-108. 19. Novak CB, MacKinnon SE, Brownlee R, Kelly L. Provocative sensory testing in carpal tunnel syndrome. J Hand Surg 1992; 17B :204-208. 20. Luchetti R, Schoenhuber R, Alfarano M, Montagna G, Pederzini L, Soragni O. Neurophysiological assessment of the early phases of carpal tunnel syndrome with the inching technique before and during operation. J Hand Surg 1991;16B:415-419.
In Reply: A 7-page letter with 20 references can hardly be ignored. I am impressed and will add the references to m y library list. The article that was written summarizes our clinical experience, no more and no less. Our cases clearly indicate that threshold E D X studies in our c o m m u n i t y do not offer help in determining prognosis for patients who were operated on for CTS. We purposely avoided possible reasons for this situation. The obvious reason is that we are extremely careful in selecting patients who undergo carpal tunnel release if their E D X findings are not abnormal. We do not operate on patients as a diagnostic procedure.