SHORT REPORTS
WHICH HAND IS WORSE? CONCORDANCE BETWEEN PATIENT PERCEPTION AND ELECTRODIAGNOSTIC RESULTS IN CARPAL TUNNEL SYNDROME COLIN B.C. RUMBOLT, BSc1 and DAVYD R. HOOPER, MD, FRCPC2 1 2
Physical Medicine and Rehabilitation, University of Manitoba, Faculty of Medicine, Manitoba, Canada Riverview Health Centre, Neuromuscular and Electrodiagnostic Clinic, PE319-One Morley Avenue, Winnipeg, Canada
Accepted 3 October 2014 ABSTRACT: Introduction: In patients with clinically diagnosed carpal tunnel syndrome (CTS) the more symptomatic hand may be different from the more severely affected hand on electrodiagnostic testing. This study aims to determine the level of agreement which should be expected between these measures and consequently the level of suspicion for co-occurring pathology which is warranted if there is discordance. Methods: This was a single center retrospective review of 252 patients referred for upper extremity electrodiagnostic evaluation who were diagnosed subsequently with CTS. Comparison was made between the patient’s perceived worst side and the more abnormal side on electrodiagnostic studies. Results: We found a significant level of agreement (j 5 0.676) between patient symptoms and electrodiagnostic testing when identifying the side with more severe CTS. Conclusions: Discordance between patient perception and electrodiagnostic results regarding which hand is affected more severely in patients with CTS should alert the clinician to possible coexisting nonneurologic pathology and prompt regional musculoskeletal examination as indicated. Muscle Nerve 51: 282–283, 2015
In patients referred for electrodiagnostic evaluation of upper extremity pain and paresthesias, carpal tunnel syndrome (CTS) is a common referral diagnosis. Lo et al. have shown that a large proportion of patients with clinically suggested CTS actually have normal electrodiagnostic studies and instead have musculoskeletal conditions that may explain their symptoms.1 Even in cases of electrodiagnostically confirmed median neuropathy at the wrist (MNW) as Nora et al. suggested, it is likely that the variation in presentation is due to coexistent disease.2 Given that even confirmed MNW can be confounded by coexistent disease, it is important for the clinician to know how often the electrodiagnostic studies should be expected to agree with the symptom presentation in terms of which hand is more severe. Furthermore, in cases of CTS where the electrodiagnostic results and symptom
Abbreviations: CTS, carpal tunnel syndrome; MNW, median neuropathy at the wrist; NCS, nerve conduction study Key words: carpal tunnel syndrome; electromyography; median neuropathy at the wrist; musculoskeletal; nerve conduction study Correspondence to: D. R Hooper; e-mail: [email protected] C 2014 Wiley Periodicals, Inc. V
Published online 7 October 2014 in Wiley Online Library (wileyonlinelibrary. com). DOI 10.1002/mus.24481
282
Perception and Electrodiagnostic Correlation
presentation do not agree, how suspicious should the clinician be for another coexisting pathology that may explain the patient’s symptoms? This study aims to assess the level of agreement between electrodiagnostic testing and patient perception in assessing which hand has more severe MNW/CTS. MATERIALS AND METHODS
This was a single-site, retrospective review of consecutive patients who had been referred for electrodiagnostic assessment during an 18-month period from June 1, 2010 to November 30, 2011. Clinical history with neurologic and regional musculoskeletal exam of upper extremities was undertaken, and any diagnoses were recorded. Electrodiagnostic examination (VIASYS Neurocare, TECA SYNERGY, Madison, Wisconsin) was conducted routinely on the most symptomatic hand. This was ascertained by asking patients which hand they believed was most affected with paresthesias (if present) or pain. The study included a minimum of sensory nerve conduction studies (NCSs) (radial-snuffbox, median-digit 3, median-digit 4, and ulnar-digit 4) and motor NCS (median-thenar). If any abnormalities were found, bilateral studies were done for comparison. If the most symptomatic hand was normal, then no further studies were pursued. The electrodiagnostically worst hand was determined by comparing median nerve conduction study results. All studies were interpreted by a Canadian Society of Clinical Neurophysiologists / American Board of Electrodiagnostic Medicine certified physician and were completed by a registered electromyography technologist or qualified physician. Statistical Analysis. To objectively assess the level of agreement between symptoms and electrodiagnostic testing regarding which side had more severe CTS/MNW, a kappa coefficient was calculated. For this analysis patients with bilateral symmetric symptoms and patients whose electrodiagnostic results were bilaterally symmetric were removed, such that only patients with symptoms and electrodiagnostic results worse on 1 side were analyzed. MUSCLE & NERVE
February 2015
Table 1. Patients with electrodiagnostically and clinically diagnosed CTS who present with a “worst” side symptomatically.*
Parameter Agreed Opposite findings Equal bilaterally Kappa coefficient agreement
% Cases where electrodiagnostic testing agreed with symptom presentation as to which hand was more severe. 76.95 12.41 10.64 j 5 0.676 95% CI: 0.578-0.775 SE: 0.050
*The kappa coefficient for patients presented with a “worst” side symptomatically and electrodiagnostically.
RESULTS
Patient referrals within the inclusion dates were inspected, and 1,007 fit our inclusion symptom presentation and were reviewed. Of this number, 89 were excluded due to prior CTS or ulnar neuropathy surgery, leaving 918 upper extremity referrals. Of the 918 patients, 326 were eventually diagnosed with CTS after electrodiagnostic and clinical testing. For our Kappa analysis those patients with bilateral and symmetric symptom presentation and electrodiagnostic results were excluded (74), leaving 252 patients included in the analysis. To assess the degree to which the symptomatic worst side was in accordance with the electrodiagnostic worst side, a kappa co-efficient of j 5 0.676 was calculated (Table 1). Table 1 also displays the percentage of cases of confirmed CTS (with 1 hand symptomatically worse) where the symptom presentation and electrodiagnostic results agreed or disagreed on which hand was worse; and the percentage found to be equal and symmetric. In cases of disagreement the most common clinical conditions diagnosed concurrently were: tennis elbow (17.14%), osteoarthritis (14.29%), and De Quervain tenosynovitis (8.57%). DISCUSSION
The kappa coefficient expresses the level of inter-observer agreement when both observers are rating the same item. In this case, observer 1 was the patient’s most symptomatic side, while observer 2 was the worst MNW determined by electrodiagnostic evaluation of the nerves. Using the benchmarks proposed by Landis and Koch makes the level of agreement, as indicated by our kappa (j 5 0.676), “substantial.”3 To put it more practically, our data indicated that 76.95% of the time
Perception and Electrodiagnostic Correlation
the symptoms and electrodiagnostic evaluation agreed on which side was worse. It is important to remember that this statistic was calculated from only patients who had clinical CTS and electrodiagnostically confirmed MNW and also had a “worst” side on both symptom presentation and electrodiagnostic testing, i.e., any symmetric presentations were excluded. Based on the kappa analysis, one should expect agreement between symptoms and electrodiagnostic results in most patients, i.e., in close to 8 of 10 patients the hand that is worse symptomatically should also be the hand that is worse electrodiagnostically; thus in patients whose symptom presentation is discordant from electrodiagnostic results the clinician should have a high index of suspicion for another coexisting condition. These results also support testing the contralateral limb whenever MNW is identified in the symptomatic limb. Only by testing both limbs can cases of discordance between symptoms and electrodiagnostics be identified. In conclusion, this study demonstrated a significant level of agreement (j 5 0.676) between patient perception and electrodiagnostic results when identifying the hand with more severe CTS/MNW. Thus in cases of discordance between symptom presentation and electrodiagnostic results the clinician should be alerted to the potential for coexisting pathology which may cloud the diagnosis; as Nora et al. suggested, it is likely that the variation in presentation of CTS is due to coexistent disease.2 In this study the most common conditions encountered in patients with discordance were: tennis elbow, osteoarthritis, and De Quervain tenosynovitis. This finding further stresses the importance of regional musculoskeletal and neurological physical exam in upper extremity electrodiagnostic referral patients. The authors thank Dr. Rasheda Rabbani for her statistical consultation and advice. We also thank the Dean of the Faculty of Medicine and the B.Sc. (med) program for student funding over the duration of this study. REFERENCES 1. Lo JK, Finestone HM, Gilbert K, Woodbury MG. Community-based referrals for electrodiagnostic studies in patients with possible carpal tunnel syndrome: what is the diagnosis? Arch Phys Med Rehabil 2002;83:598–603. 2. Nora DB, Becker J, Ehlers JA, Gomes I. Clinical features of 1039 patients with neurophysiological diagnosis of carpal tunnel syndrome. Clin Neurol Neurosurg 2004;107:64–69. 3. Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics 1977;33:159–174.
MUSCLE & NERVE
February 2015
283
WHICH HAND IS WORSE? CONCORDANCE BETWEEN PATIENT PERCEPTION AND ELECTRODIAGNOSTIC RESULTS IN CARPAL TUNNEL SYNDROME COLIN B.C. RUMBOLT, BSc1 and DAVYD R. HOOPER, MD, FRCPC2 1 2
Physical Medicine and Rehabilitation, University of Manitoba, Faculty of Medicine, Manitoba, Canada Riverview Health Centre, Neuromuscular and Electrodiagnostic Clinic, PE319-One Morley Avenue, Winnipeg, Canada
Accepted 3 October 2014 ABSTRACT: Introduction: In patients with clinically diagnosed carpal tunnel syndrome (CTS) the more symptomatic hand may be different from the more severely affected hand on electrodiagnostic testing. This study aims to determine the level of agreement which should be expected between these measures and consequently the level of suspicion for co-occurring pathology which is warranted if there is discordance. Methods: This was a single center retrospective review of 252 patients referred for upper extremity electrodiagnostic evaluation who were diagnosed subsequently with CTS. Comparison was made between the patient’s perceived worst side and the more abnormal side on electrodiagnostic studies. Results: We found a significant level of agreement (j 5 0.676) between patient symptoms and electrodiagnostic testing when identifying the side with more severe CTS. Conclusions: Discordance between patient perception and electrodiagnostic results regarding which hand is affected more severely in patients with CTS should alert the clinician to possible coexisting nonneurologic pathology and prompt regional musculoskeletal examination as indicated. Muscle Nerve 51: 282–283, 2015
In patients referred for electrodiagnostic evaluation of upper extremity pain and paresthesias, carpal tunnel syndrome (CTS) is a common referral diagnosis. Lo et al. have shown that a large proportion of patients with clinically suggested CTS actually have normal electrodiagnostic studies and instead have musculoskeletal conditions that may explain their symptoms.1 Even in cases of electrodiagnostically confirmed median neuropathy at the wrist (MNW) as Nora et al. suggested, it is likely that the variation in presentation is due to coexistent disease.2 Given that even confirmed MNW can be confounded by coexistent disease, it is important for the clinician to know how often the electrodiagnostic studies should be expected to agree with the symptom presentation in terms of which hand is more severe. Furthermore, in cases of CTS where the electrodiagnostic results and symptom
Abbreviations: CTS, carpal tunnel syndrome; MNW, median neuropathy at the wrist; NCS, nerve conduction study Key words: carpal tunnel syndrome; electromyography; median neuropathy at the wrist; musculoskeletal; nerve conduction study Correspondence to: D. R Hooper; e-mail: [email protected] C 2014 Wiley Periodicals, Inc. V
Published online 7 October 2014 in Wiley Online Library (wileyonlinelibrary. com). DOI 10.1002/mus.24481
282
Perception and Electrodiagnostic Correlation
presentation do not agree, how suspicious should the clinician be for another coexisting pathology that may explain the patient’s symptoms? This study aims to assess the level of agreement between electrodiagnostic testing and patient perception in assessing which hand has more severe MNW/CTS. MATERIALS AND METHODS
This was a single-site, retrospective review of consecutive patients who had been referred for electrodiagnostic assessment during an 18-month period from June 1, 2010 to November 30, 2011. Clinical history with neurologic and regional musculoskeletal exam of upper extremities was undertaken, and any diagnoses were recorded. Electrodiagnostic examination (VIASYS Neurocare, TECA SYNERGY, Madison, Wisconsin) was conducted routinely on the most symptomatic hand. This was ascertained by asking patients which hand they believed was most affected with paresthesias (if present) or pain. The study included a minimum of sensory nerve conduction studies (NCSs) (radial-snuffbox, median-digit 3, median-digit 4, and ulnar-digit 4) and motor NCS (median-thenar). If any abnormalities were found, bilateral studies were done for comparison. If the most symptomatic hand was normal, then no further studies were pursued. The electrodiagnostically worst hand was determined by comparing median nerve conduction study results. All studies were interpreted by a Canadian Society of Clinical Neurophysiologists / American Board of Electrodiagnostic Medicine certified physician and were completed by a registered electromyography technologist or qualified physician. Statistical Analysis. To objectively assess the level of agreement between symptoms and electrodiagnostic testing regarding which side had more severe CTS/MNW, a kappa coefficient was calculated. For this analysis patients with bilateral symmetric symptoms and patients whose electrodiagnostic results were bilaterally symmetric were removed, such that only patients with symptoms and electrodiagnostic results worse on 1 side were analyzed. MUSCLE & NERVE
February 2015
Table 1. Patients with electrodiagnostically and clinically diagnosed CTS who present with a “worst” side symptomatically.*
Parameter Agreed Opposite findings Equal bilaterally Kappa coefficient agreement
% Cases where electrodiagnostic testing agreed with symptom presentation as to which hand was more severe. 76.95 12.41 10.64 j 5 0.676 95% CI: 0.578-0.775 SE: 0.050
*The kappa coefficient for patients presented with a “worst” side symptomatically and electrodiagnostically.
RESULTS
Patient referrals within the inclusion dates were inspected, and 1,007 fit our inclusion symptom presentation and were reviewed. Of this number, 89 were excluded due to prior CTS or ulnar neuropathy surgery, leaving 918 upper extremity referrals. Of the 918 patients, 326 were eventually diagnosed with CTS after electrodiagnostic and clinical testing. For our Kappa analysis those patients with bilateral and symmetric symptom presentation and electrodiagnostic results were excluded (74), leaving 252 patients included in the analysis. To assess the degree to which the symptomatic worst side was in accordance with the electrodiagnostic worst side, a kappa co-efficient of j 5 0.676 was calculated (Table 1). Table 1 also displays the percentage of cases of confirmed CTS (with 1 hand symptomatically worse) where the symptom presentation and electrodiagnostic results agreed or disagreed on which hand was worse; and the percentage found to be equal and symmetric. In cases of disagreement the most common clinical conditions diagnosed concurrently were: tennis elbow (17.14%), osteoarthritis (14.29%), and De Quervain tenosynovitis (8.57%). DISCUSSION
The kappa coefficient expresses the level of inter-observer agreement when both observers are rating the same item. In this case, observer 1 was the patient’s most symptomatic side, while observer 2 was the worst MNW determined by electrodiagnostic evaluation of the nerves. Using the benchmarks proposed by Landis and Koch makes the level of agreement, as indicated by our kappa (j 5 0.676), “substantial.”3 To put it more practically, our data indicated that 76.95% of the time
Perception and Electrodiagnostic Correlation
the symptoms and electrodiagnostic evaluation agreed on which side was worse. It is important to remember that this statistic was calculated from only patients who had clinical CTS and electrodiagnostically confirmed MNW and also had a “worst” side on both symptom presentation and electrodiagnostic testing, i.e., any symmetric presentations were excluded. Based on the kappa analysis, one should expect agreement between symptoms and electrodiagnostic results in most patients, i.e., in close to 8 of 10 patients the hand that is worse symptomatically should also be the hand that is worse electrodiagnostically; thus in patients whose symptom presentation is discordant from electrodiagnostic results the clinician should have a high index of suspicion for another coexisting condition. These results also support testing the contralateral limb whenever MNW is identified in the symptomatic limb. Only by testing both limbs can cases of discordance between symptoms and electrodiagnostics be identified. In conclusion, this study demonstrated a significant level of agreement (j 5 0.676) between patient perception and electrodiagnostic results when identifying the hand with more severe CTS/MNW. Thus in cases of discordance between symptom presentation and electrodiagnostic results the clinician should be alerted to the potential for coexisting pathology which may cloud the diagnosis; as Nora et al. suggested, it is likely that the variation in presentation of CTS is due to coexistent disease.2 In this study the most common conditions encountered in patients with discordance were: tennis elbow, osteoarthritis, and De Quervain tenosynovitis. This finding further stresses the importance of regional musculoskeletal and neurological physical exam in upper extremity electrodiagnostic referral patients. The authors thank Dr. Rasheda Rabbani for her statistical consultation and advice. We also thank the Dean of the Faculty of Medicine and the B.Sc. (med) program for student funding over the duration of this study. REFERENCES 1. Lo JK, Finestone HM, Gilbert K, Woodbury MG. Community-based referrals for electrodiagnostic studies in patients with possible carpal tunnel syndrome: what is the diagnosis? Arch Phys Med Rehabil 2002;83:598–603. 2. Nora DB, Becker J, Ehlers JA, Gomes I. Clinical features of 1039 patients with neurophysiological diagnosis of carpal tunnel syndrome. Clin Neurol Neurosurg 2004;107:64–69. 3. Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics 1977;33:159–174.
MUSCLE & NERVE
February 2015
283
