Utilization of Electrodiagnostic Testing for Carpal Tunnel Syndrome by General Practitioners Prior to Hand Surgery Consultation

Abstract

Background:Carpal tunnel syndrome (CTS) is the most common peripheral mononeuropathy and thus is frequently encountered by general practitioners (GPs). The aim of this study is to investigate the referral pattern of GPs with regard to electrodiagnostic (EDX) testing for suspected CTS prior to hand surgery consultation, as well as to investigate the results of EDX testing for suspected CTS when requested by GPs prior to evaluation by a hand surgeon. Methods: We retrospectively reviewed patients referred to our hand surgery clinic over a consecutive 2-year period for suspected CTS. Results: A total of 403 patients were referred to our hand surgery clinic from January 1, 2016, to December 31, 2017. Of the 403, 295 (73.2%) were referred by GPs. GPs obtained prereferral EDX testing in 198 (67.1%) of these patients. EDX testing confirmed their diagnosis in 177 patients (89.4%). There were 21 patients (10.6%) identified with normal EDX testing and a more likely diagnosis reached based on clinical examination. Conclusions: GPs make up the majority of our referrals for CTS, and they obtain EDX testing prior to consultation in two-thirds of referrals. GPs appear to accurately utilize EDX testing to confirm their diagnosis prior to referral and have a low rate of normal testing where symptoms are more readily explained by an alternative diagnosis.

Introduction

Carpal tunnel syndrome (CTS) is the most common peripheral entrapment mononeuropathy. Studies have demonstrated an incidence of 2.8 per 1000 individuals.^1,2 Patients typically present with paresthesias or numbness in the median nerve distribution. Paresthesias often cause patients to awaken at night. In cases of severe or prolonged compression, patients may have weakness and atrophy of the thenar musculature.³

The diagnosis of CTS is typically based on history and physical examination findings. However, the diagnostic validity of commonly used clinical tests is debated. Studies have shown the Phalen test to have a sensitivity ranging from 10% to 88% and specificity ranging from 47% to 100%.^4-6 In addition, multiple studies have found the Tinel sign to have no diagnostic value with regard to CTS.^7-9 Also, CTS can have an atypical presentation with symptoms that differ from those previously mentioned. Due to these factors, electrodiagnostic (EDX) testing is commonly utilized to confirm the diagnosis of CTS. In addition, hand surgeons frequently utilize EDX testing to advise patients on carpal tunnel release and provide expectations regarding outcomes after surgery. Therefore, having testing done prior to referral may be both cost and time saving, as a potential additional office visit could be avoided.¹⁰

The aim of the present study is to retrospectively identify the referral pattern of general practitioners (GPs) with regard to EDX testing for CTS prior to evaluation by a hand surgeon, as well as to investigate the results of this testing and determine the proportion of patients with normal testing and identify the more likely clinical diagnosis.

Material and Methods

The medical records of all patients with possible CTS who were referred to our outpatient hand surgery office at Carolinas HealthCare System NorthEast in Concord, North Carolina, from January 1, 2016, through December 31, 2017, were retrospectively reviewed. The referring provider’s specialty was identified, and only those confirmed to be GPs were included in this study. Referrals made by specialists (ie, neurologists, orthopedists, etc) were excluded. Each patient’s reason for referral was also identified, and only those indicating CTS were included. In addition, patients who had undergone multiple EDX studies for CTS prior to referral and those with a history of previous carpal tunnel release were excluded.

The results of EDX testing for all included patients were also reviewed, and the proportion of abnormal and normal test results were identified. EDX testing was considered positive or negative based on the interpretation of the test by the performing physician. Further review of the record was carried out on all patients who had been referred for EDX testing but had a normal result. Review of the initial evaluation by the hand surgeon revealed a more likely alternative diagnosis in all cases where EDX testing for CTS was normal.

Results

A total of 403 patients were referred to our hand surgery clinic for CTS over a 2-year period, of which 295 (73.2%) were sent by GPs and included in the present study. In 198 out of the 295 patients (67.1%), the GPs obtained EDX testing to confirm their diagnosis of CTS. Of these patients, EDX testing was consistent with CTS in 177 (89.4%). In 21 patients (10.6%), EDX testing was normal. In all 21 of these patients, another clinical diagnosis was reached upon consultation by a hand surgeon. None of the 21 patients with normal EDX testing were diagnosed with concurrent CTS based on their clinical examination. Table 1 summarizes the demographics and alternative diagnoses of the 21 patients with normal EDX testing. There were 95 patients referred for CTS without any EDX testing. While evaluating this group was not part of our primary endpoint, we did note that the majority of these patients were ultimately found to have to have CTS based on clinical exam or EDX ordered by the hand surgeon. It is unclear as to why GPs chose not to pursue EDX testing in these patients.

Table 1.

Demographics and Alternative Diagnoses in Patients Without Electrodiagnostic Findings of CTS.

Age	Sex	Past medical history	Alternative diagnosis
66	Female	Diabetes, hypothyroidism	Index trigger finger
46	Female	Fibromyalgia	De Quervain tenosynovitis
53	Female	Diabetes	De Quervain tenosynovitis
47	Female	None	Chronic thumb MP UCL tear
51	Female	None	Thumb CMC osteoarthritis
58	Female	None	Thumb CMC osteoarthritis
72	Female	Fibromyalgia	De Quervain tenosynovitis
61	Female	Fibromyalgia, Rheumatoid arthritis	Kienböck disease
65	Female	Diabetes, hypothyroidism	Thumb CMC osteoarthritis
64	Female	Rheumatoid arthritis	Thumb CMC osteoarthritis
54	Female	Multiple sclerosis	Thumb CMC osteoarthritis
63	Female	Diabetes	De Quervain tenosynovitis
59	Male	None	Thumb CMC osteoarthritis
67	Female	Fibromyalgia	Thumb trigger finger
54	Female	Hypothyroidism	De Quervain tenosynovitis
54	Female	None	Thumb CMC osteoarthritis
42	Female	None	De Quervain tenosynovitis
36	Female	None	De Quervain tenosynovitis
48	Female	Fibromyalgia	Thumb CMC osteoarthritis
64	Male	None	Thumb trigger finger
59	Female	Diabetes	De Quervain tenosynovitis

Note. CTS = carpal tunnel syndrome; MP UCL = metacarpophalangeal joint ulnar collateral ligament; CMC = carpometacarpal.

Discussion

This study provides insight into both the prereferral utilization of EDX testing for CTS by GPs, as well as how accurate they are with that testing. There are limited studies on this topic, and the majority of these looked at all patients referred for EDX testing, not just those with a suspected diagnosis of CTS.

Cocito et al investigated the appropriateness of requests for EDX testing between GPs and specialists for all referrals to their neurophysiology lab. They determined that only 55% of requests by GPs were appropriate, compared with 77% of requests made by specialists.¹¹ Similar to our study, Lo et al examined patient referrals for EDX testing for possible CTS and the proportion of those with negative testing. Of the 348 patients in their study, 250 were referred by GPs, and testing confirmed the GPs suspicion of CTS in only 51.2%.¹² Of the patients in their study with normal testing, they identified a high rate of musculoskeletal disorders that were felt to be the cause of the patients’ symptoms.¹² Claes et al looked specifically at patients referred by GPs for EDX testing to confirm CTS. They identified 40 out of 232 patients (17%) with a clinical examination not consistent with CTS and normal EDX testing.¹³ This is relatively similar to our rate of 10.6%. We were also able to identify a more likely diagnosis in our patients, all of which happened to be musculoskeletal disorders. This is similar to the finding of Lo et al that was previously mentioned. This finding can likely be explained by the more specific knowledge of the differential diagnoses for the hand surgeon compared with the GP.

Our study does have some inherent limitations given its retrospective nature. We studied only a single site in one city, so results cannot necessarily be generalized to other regions. It is also possible that when some GPs get normal EDX testing, they no longer feel that referral to a hand surgeon is necessary. Finally, it is also possible that some patients with positive EDX testing did not have symptoms or clinical examination findings consistent with a diagnosis of CTS.

Conclusion

The majority of patients seen in our hand surgery office for CTS are referred by GPs. They frequently utilized EDX testing to confirm CTS prior to referral to a hand surgeon. In our study, GPs effectively utilized EDX testing, as it confirmed their diagnosis of CTS in 89.4% of patients. This is fairly consistent with prior studies on this topic. Given this finding, it is likely beneficial to have GPs order EDX testing for suspected CTS prior to referral as it could potentially reduce time and costs associated with multiple office visits.