Abstract
Background
Accurate diagnosis of carpal tunnel syndrome is key to successful treatment. At our center a treatment pathway was recently established for patients with carpal tunnel syndrome. Within this pathway patients are assessed by their community practitioner. Patients who fail to improve with conservative treatment and have a positive nerve conduction study are put forward for surgery without a specialist assessment. Recent literature has shown nerve conduction study may produce a high rate of false-positive results when used to diagnose carpal tunnel syndrome. The aim of this study was to retrospectively review outcomes of carpal tunnel decompression surgery in patients whose diagnoses was based on a community practitioner assessment and positive nerve conduction study.
Methods
All patients who had carpal tunnel release surgery between August 1, 2017 and August 31, 2018 at our center were screened for eligibility. Data from hospital records and a standardized telephone questionnaire was used to assess surgical outcome.
Results
The final study population included 128 operated hands. The mean follow up time after surgery was 9.6 months. We found 79% of patients reported significant improvement of their symptoms following carpal tunnel release. The overall complication rate was 2.3%.
Conclusion
This study has demonstrated good outcomes from carpal tunnel decompressive surgery are possible in a cohort of patients whose diagnosis was made on the basis of a positive nerve conduction study and community practitioner assessment.
Keywords: Carpal tunnel syndrome, Surgical outcomes, Nerve conduction studies
1. Introduction
Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy in the upper limb.1 The average incidence reported in New Zealand was 136 per 100,000-person years.2 Open carpal tunnel surgical release is a simple and effective treatment of this condition.3 However, as there is a wide variety of conditions that cause similar neurological disturbance in the hand,4 the key to successful treatment is to establish the correct diagnosis.
In 2015 at a hospital in New Zealand, a treatment pathway was established for patients with symptoms of carpal tunnel syndrome. This pathway excluded orthopedic assessment prior to decompression surgery. Within this pathway patients are assessed by their community practitioner who determines individual treatment. Most patients receive conservative treatment including physiotherapy referral, wrist splinting and/or a steroid injection. Patients who fail to improve with conservative treatment or have severe or progressive symptoms are referred for surgery. Referral requirements for surgery are a positive nerve conduction study or temporary relief from a steroid injection. If either of these two criteria are satisfied the patient may proceeds to carpal tunnel decompressive surgery without a specialist opinion prior to surgery.
Various diagnostic tools for carpal tunnel syndrome have been evaluated, particularly nerve conduction study (NCS). The advantage of NCS is to offer an objective measure of conduction speed against the normal average population with a clear cut-off reference. It also provides a baseline to monitor neurological response to treatment.5 Although NCS has been found to be highly sensitive for carpal tunnel syndrome, its reported specificity varies and has been found to be as low as 50% in one study.6 Given the arguably low specificity, there is concern of using nerve conduction study as a diagnostic tool to guide treatment for carpal tunnel syndrome.
This study aimed to retrospectively assess outcomes of carpal tunnel release in patients with suspected carpal tunnel syndrome from community referrals, when the decision to proceed to surgery was guided by community practitioner assessment and nerve conduction study.
2. Methods
This study is a retrospective cohort study. Ethics approval was obtained from our institution prior to starting the research. Verbal consent was obtained from all participants.
An audit of patients who underwent carpal tunnel decompressive surgery at a hospital in New Zealand between the dates of the August 1, 2017 and the August 31, 2018 was undertaken. These patients had been referred from their community practitioners with signs and symptoms suggestive of carpal tunnel syndrome. All records were screened and patients were excluded if they 1) didn’t have nerve conduction study results; 2) had previous carpal tunnel release on the same hand 3) had a history of other neurological disorder that may compromise their reported outcome. Patients that met the inclusion criteria were followed up with a six-item telephone questionnaire. The questionnaire was developed based on other questionnaires used to assess patient reported outcome and satisfaction following carpal tunnel decompression surgery.7, 8, 9 The questionnaire is provided in Table 1. Patients that could not communicate in English or that had a recent history of trauma were excluded at this point. Demographic data was collected from hospital records and listed in Table 2. Surgical complications were recorded from postoperative clinic follow up records.
Table 1.
Questionnaire summary.
| Primary Outcome | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| How did the surgery treat the symptoms you were experiencing in your hand and wrist? |
Cured 25.8% |
Greatly Improved 53.1% |
Slightly Improved 14.8% |
No Change 4.7% |
Worse 1.6% |
||||
|
Secondary Outcome | |||||||||
| Are you satisfied with the results of your surgery? |
Very satisfied 50.0% |
Satisfied 37.5% |
Unsatisfied 11.7% |
Very Unsatisfied 0.8% |
Unsure 0% |
||||
|
Other questionnaire items | |||||||||
| Would you have this surgery again if it was required on the other hand? | Definitely yes 46.0% | Probably yes 29.7% | Probably not 1.8% | Definitely not 4.5% | Unsure 18.0% | ||||
| Would you recommend this surgery to a friend or family member if they also had carpal tunnel syndrome? | Definitely yes 60.9% | Probably yes 29.7% | Probably not 3.1% | Definitely not 0.8% | Unsure 5.5% | ||||
| How did the surgery meet your preoperative expectations? | Excellently 32.8% | Very Well 45.3% | Well 8.6% | Fairly 5.5% | Poorly 7.0% | Unsure 0.8% | |||
| How did the surgery improve your ability to perform daily tasks? | Excellently 32.0% | Very Well 36.7% | Well 16.4% | Fairly 4.7% | Poorly 7.0% | Unsure 3.1% | |||
Table 2.
Demographics and follow up time.
| Gender | |
|---|---|
| Male | 32 (28.1%) |
| Female |
82 (71.9%) |
|
Age, years | |
| Mean (range, SD) |
60 (25–89, 14.9) |
|
Post-operative follow-up, months | |
| Mean (range, SD) |
9.6 (3.5–16.1, 3.6) |
|
Wait time to surgery from referral, months | |
| Mean (range, SD) | 2.1 (0.5–6.5, 1.3) |
Community practitioners followed a standardized assessment in patients suspected of CTS. This assessment consisted of a clinical history for symptoms and risk factors. Examination consisted of assessing for sensory and motor deficits in the hand and the patient’s response to provocative tests.
The severity of median nerve conduction deficit was graded in accordance with Bland’s grading scale for carpal tunnel syndrome.10 Grading is summarized on Table 3.
Table 3.
NCS grading and results.
| NCS Grade | Grading explanation | Wrists |
|---|---|---|
| Normal | No median nerve deficit | 1 (0.8%) |
| Very mild | CTS demonstrable only on most sensitive tests. | 0 (0.0%) |
| Mild | Sensory nerve conduction velocity slow on finger/wrist measurement, normal terminal motor latency. | 13 (10.2%) |
| Moderate | Sensory potential preserved with motor slowing, distal motor latency to APB < 6.5 ms. | 10 (7.8%) |
| Severe | Sensory potentials absent but motor response preserved, distal motor latency to APB < 6.5 ms. | 32 (25.0%) |
| Very severe | Terminal latency to APB > 6.5 ms. | 27 (21.1%) |
| Extremely severe | Sensory and motor potentials effectively unrecordable (surface motor potential from APB < 0.2 mV amplitude) | 45 (35.2%) |
APB = Abductor pollicis brevis.
Carpal tunnel release operations were performed by the orthopedic service at our center. Consent for the operation was obtained by the operating surgeon on the day of the patient’s surgery. Patients were consented for bleeding, infection, pain, failure to release the median nerve, persistent symptoms despite surgery, damage to median nerve or other adjacent structures, and chronic regional pain syndrome. Operations were performed under local anesthesia using standard open technique with a tourniquet. Operations were performed by an experienced hand surgeon or their supervised trainee.
The primary outcome measure was patient reported symptom resolution following surgery. Our secondary outcome measure was patient reported satisfaction with the results of their surgery. To avoid influencing patient responses, the telephone questionnaire was administered in a standardized format by one member of the research team.
2.1. Statistical methods
A Spearman’s rank-order correlation was used to assess correlation between items on the questionnaire and severity of median nerve conduction deficit on nerve conduction study. A p value of ≤.05 was considered statistically significant.
3. Results
Between August 1, 2017 and August 31, 2018; 212 hands from 188 patients underwent carpal tunnel decompression surgery at our center and were screened for eligibility in the study. Of these 188 patients: 48 didn’t have a nerve conduction study results, 9 had another confounding neurological disorder, 7 were unable to answer the phone questionnaire, 6 were unable to be contacted, 2 had a history of trauma and 2 declined to participate in the study. The final study population included 128 operated hands from 114 patients. 14 patients had both hands released in separate operations during the study period.
3.1. Descriptive data
The mean age of participants was 60 years old (range 25–89) (SD = 14.9). 71.9% of participants were female and 28.1% of participants were male. Mean time of follow up after surgery by phone interview was 9.6 months (range 3.5–16.1) (SD = 3.6). Table 2. The response rate for eligible participants was 93%. Mean wait time for surgery from community practitioner referral was 2.1 months (range 0.5–6.5) (SD = 1.3). Table 2. Grades from Nerve conduction studies are summarized on Table 3.
3.2. Complications
Three patients experienced complications from surgery. The complications were complex regional pain syndrome, hematoma and superficial infection. The overall complication rate was 2.3%. Table 4.
Table 4.
Surgical complications.
| Complication | Wrists |
|---|---|
| Complex regional pain syndrome | 1 |
| Hematoma | 1 |
| Superficial infection | 1 |
3.3. Outcome data
Primary outcome (symptom resolution): 79% of patients reported cured or greatly improved symptoms at the time of follow up, 21% of patients reported slightly improved, no change or worse symptoms at the time of follow up.
Secondary outcome (satisfaction): 88% of patients reported being very satisfied or satisfied at the results of their surgery, 13% of patients reported being unsatisfied or very unsatisfied with the results of their surgery. Other results from the questionnaire are summarized in Table 1.
3.4. Other analyses
A Spearman’s rank-order correlation showed the relationship between symptom resolution and satisfaction to be monotonic, as assessed by visual inspection of a scatterplot. There was a strong positive correlation between symptom resolution and satisfaction, rs (127) = 0.611, p < .0005.
Statistical analysis using Spearman’s rank-order correlation showed no correlation between pre-surgical severity on nerve conduction studies and symptom resolution, rs (121) = 0.075, p = .414.
4. Discussion
We defined a successful operation as the patient reporting “cured” or “greatly improved” to the question regarding symptom resolution. Therefore 79% of patients in our study population had a successful operation. This finding is consistent with other research reporting on outcomes from carpal tunnel decompression surgery.8
We found that 13% of patients in our study were unsatisfied or very unsatisfied with the results of their surgery. A moderately strong positive correlation was identified between patient reported satisfaction and symptom resolution in our study, this finding is supports other research that have correlated patient reported satisfaction and symptom resolution9,11 and demonstrates unsurprisingly that symptom resolution is an important factor in determining postoperative patient satisfaction.
Gerritsen et al. conducted a randomized control trial and used the same primary outcome measure as the current study. In their surgery group they found that 6% of patients had an unsuccessful outcome at 6 months follow up.12 This is a much superior outcome than observed in the current cohort. The patients in this study were more tightly selected and diagnosis was based on a positive nerve conduction study and an assessment by a surgeon. Part of the difference observed in the current cohort may be due to omission of a formal clinical assessment by a surgeon, which may have reduced diagnostic accuracy and resulted in less suitable candidates being put forward for surgery.
Other factors may have influenced patient reported outcomes in our cohort. Increased severity and chronicity of carpal tunnel compression before surgery may correlate with prolonged and incomplete symptom recovery.13, 14, 15, 16 However, we found no correlation between pre-surgical severity on nerve conduction study and post-surgical symptoms resolution. Secondly, we utilized a standardized open surgical decompression technique that was well described by previous literature with a low surgical complication rate (2.3%) meaning poor surgical technique is unlikely to influence our results. Lastly our cohort included all-comers referred for treatment from community health care over a year period. Therefore certain known risk factors for inferior outcome such as significant comorbidities, worker’s compensation17 and mental illness18 were not over-represented in our study cohort.
Concern about the use of nerve conduction study in the diagnosis of carpal tunnel syndrome has been discussed in recent literature. A recent study reported nerve conduction study to have specificity as low as 50% when clinical diagnosis is used as the reference standard.6 Another study comparing CTS-6, nerve conduction study and ultrasound found that nerve conduction study has the lowest specificity and sensitivity of the three tests.19 The false positive findings of median nerve compression in patients without symptoms and signs was highlighted in a study by Fowler et al., which, found a false positive rate of 43% in their group of patients.20 Despite these concerns our results suggest the combination of nerve conduction study and community practitioner assessment diagnosed carpal tunnel syndrome sufficiently to produce satisfactory outcomes from carpal tunnel decompressive surgery. Of note, one patient in our cohort returned a normal nerve conduction study. This patient reported good symptom resolution and satisfaction highlighting the fact that nerve conduction studies are not entirely sensitive for CTS.
Ethical questions are raised by the treatment pathway at our center. For instance, is it ethical for surgeons to operate on a patient in whom they have not assessed or diagnosed CTS themselves? In our study we have shown acceptable outcomes in a cohort of patients who were not formally assessed by the operating surgeon. This potentially raises an issue with accountability if the patient has a poor outcome. In the case of a poor outcome, should responsibility lie with the operating surgeon or would the community practitioner that recommended the patient for surgery be responsible? These questions also apply to other situations as healthcare shifts to a multidisciplinary approach. One advantage of our pathway is the efficient use of healthcare resources. More of the surgeon’s time is spent operating instead of assessing patients in clinic. This efficient use of surgical resources may increase patients’ access to surgical treatment.
This study had several limitations. Selection bias could have affected our results due to its retrospective design.21 This was minimized as we achieved a high response rate of 93% in our population with telephone survey. It has also been shown that patients are more likely to give a positive response to a telephone questionnaire when compared to a paper questionnaire.22 This may have biased our results towards more favorable patient outcome that what truly occurred. The telephone questionnaire by patients were also subject to recall bias. As we were asking patients to rate their current symptoms and function rather than rely on recollection, recall bias was minimized.
This study has demonstrated good outcomes from carpal tunnel decompressive surgery are possible in a cohort of patients whose diagnosis was made on the basis of a positive nerve conduction study and community practitioner assessment.
Declaration of competing interest
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
References
- 1.Aroori S., Spence R.A. Carpal tunnel syndrome. Ulster Med J. 2008;77(1):6–17. [PMC free article] [PubMed] [Google Scholar]
- 2.English J.H., Gwynne-Jones D.P. Incidence of carpal tunnel syndrome requiring surgical decompression: a 10.5-year review of 2,309 patients. J Hand Surg Am. 2015;40(12):2427–2434. doi: 10.1016/j.jhsa.2015.07.029. [DOI] [PubMed] [Google Scholar]
- 3.Zuo D., Zhou Z., Wang H. Endoscopic versus open carpal tunnel release for idiopathic carpal tunnel syndrome: a meta-analysis of randomized controlled trials. J Orthop Surg Res. 2015;10:12. doi: 10.1186/s13018-014-0148-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Butler D.P., Murray A., Horwitz M. Hand manifestations of neurological disease: some alternatives to consider. Br J Gen Pract. 2016;66(647):331–332. doi: 10.3399/bjgp16X685549. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Zhang D., Earp B.E., Blazar P. Utility of ‘baseline’ electrodiagnostic studies for carpal tunnel release. J Hand Surg. 2019;44(3):273–277. doi: 10.1177/1753193418815546. [DOI] [PubMed] [Google Scholar]
- 6.Wang W.L., Buterbaugh K., Kadow T.R., Goitz R.J., Fowler J.R. A prospective comparison of diagnostic tools for the diagnosis of carpal tunnel syndrome. J Hand Surg Am. 2018;43(9):833–836 e2. doi: 10.1016/j.jhsa.2018.05.022. [DOI] [PubMed] [Google Scholar]
- 7.Tang C.Q.Y., Lai S.W.H., Tay S.C. Long-term outcome of carpal tunnel release surgery in patients with severe carpal tunnel syndrome. Bone Joint Lett J. 2017;99-B(10):1348–1353. doi: 10.1302/0301-620X.99B10.BJJ-2016-0587.R2. [DOI] [PubMed] [Google Scholar]
- 8.Bland J.D. Treatment of carpal tunnel syndrome. Muscle Nerve. 2007;36(2):167–171. doi: 10.1002/mus.20802. [DOI] [PubMed] [Google Scholar]
- 9.Hamilton D.F., Lane J.V., Gaston P. What determines patient satisfaction with surgery? A prospective cohort study of 4709 patients following total joint replacement. BMJ Open. 2013;3(4) doi: 10.1136/bmjopen-2012-002525. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Bland J.D. A neurophysiological grading scale for carpal tunnel syndrome. Muscle Nerve. 2000;23(8):1280–1283. doi: 10.1002/1097-4598(200008)23:8<1280::aid-mus20>3.0.co;2-y. [DOI] [PubMed] [Google Scholar]
- 11.Ingram J., Mauck B.M., Thompson N.B., Calandruccio J.H. Cost, value, and patient satisfaction in carpal tunnel surgery. Orthop Clin N Am. 2018;49(4):503–507. doi: 10.1016/j.ocl.2018.06.005. [DOI] [PubMed] [Google Scholar]
- 12.Gerritsen A.A., de Vet H.C., Scholten R.J., Bertelsmann F.W., de Krom M.C., Bouter L.M. Splinting vs surgery in the treatment of carpal tunnel syndrome: a randomized controlled trial. J Am Med Assoc. 2002;288(10):1245–1251. doi: 10.1001/jama.288.10.1245. [DOI] [PubMed] [Google Scholar]
- 13.Tang C.Q.Y., Lai S.W.H., Tay S.C. Patient-reported outcomes of carpal tunnel release surgery in patients with bilateral severe carpal tunnel syndrome. J Hand Surg. 2017;42(9):932–936. doi: 10.1177/1753193417721456. [DOI] [PubMed] [Google Scholar]
- 14.Jansen M.C., Evers S., Slijper H.P. Predicting clinical outcome after surgical treatment in patients with carpal tunnel syndrome. J Hand Surg Am. 2018;43(12):1098–10106 e1. doi: 10.1016/j.jhsa.2018.05.017. [DOI] [PubMed] [Google Scholar]
- 15.Kronlage S.C., Menendez M.E. The benefit of carpal tunnel release in patients with electrophysiologically moderate and severe disease. J Hand Surg Am. 2015;40(3):438–444 e1. doi: 10.1016/j.jhsa.2014.12.012. [DOI] [PubMed] [Google Scholar]
- 16.Fowler J.R., Munsch M., Huang Y., Hagberg W.C., Imbriglia J.E. Pre-operative electrodiagnostic testing predicts time to resolution of symptoms after carpal tunnel release. J Hand Surg. 2016;41(2):137–142. doi: 10.1177/1753193415576248. [DOI] [PubMed] [Google Scholar]
- 17.Turner A., Kimble F., Gulyas K., Ball J. Can the outcome of open carpal tunnel release be predicted?: a review of the literature. ANZ J Surg. 2010;80(1-2):50–54. doi: 10.1111/j.1445-2197.2009.05175.x. [DOI] [PubMed] [Google Scholar]
- 18.Maempel J.F., Jenkins P.J., McEachan J.E. The relationship of mental health status to functional outcome and satisfaction after carpal tunnel release. J Hand Surg. 2020;45(2):147–152. doi: 10.1177/1753193419866400. [DOI] [PubMed] [Google Scholar]
- 19.Fowler J.R., Cipolli W., Hanson T. A comparison of three diagnostic tests for carpal tunnel syndrome using latent class Analysis. J Bone Jt Surg Am. 2015;97(23):1958–1961. doi: 10.2106/JBJS.O.00476. [DOI] [PubMed] [Google Scholar]
- 20.Fowler J.R., Byrne K., Pan T., Goitz R.J. False-positive rates for nerve conduction studies and ultrasound in patients without clinical signs and symptoms of carpal tunnel syndrome. J Hand Surg Am. 2019;44(3):181–185. doi: 10.1016/j.jhsa.2018.11.010. [DOI] [PubMed] [Google Scholar]
- 21.Geneletti S., Richardson S., Best N. Adjusting for selection bias in retrospective, case–control studies. Biostatistics. 2008;10(1):17–31. doi: 10.1093/biostatistics/kxn010. [DOI] [PubMed] [Google Scholar]
- 22.Bowling A. Mode of questionnaire administration can have serious effects on data quality. J Public Health. 2005;27(3):281–291. doi: 10.1093/pubmed/fdi031. [DOI] [PubMed] [Google Scholar]