Clinical diagnosis of carpal tunnel syndrome: Old tests–new concepts

Abstract

Background

The diagnosis of carpal tunnel syndrome (CTS) continues to be neurophysiologically and clinically controversial. Earlier data concluding that the higher prevalence of persons with symptoms suggestive of CTS but without evidence of median mononeuropathy highlights the need for a better understanding of the underlying pathophysiology and natural history of CTS to provide a less empirical foundation for diagnosis and clinical management.

Objective

To examine the relationship between the clinical manifestations of CTS with the outcome of the diagnostic tools (nerve conduction tests and ultrasonography), and its implication for clinical practice.

Methods

Two-hundred and thirty-two patients (69 male and 163 female, ages ranging between 20 and 91 years) with CTS manifestations and 182 controls were included in this study. Diagnosis of CTS was based on the American Academy of Neurology clinical diagnostic criteria. All patients and controls completed a patient oriented questionnaire, were subjected to clinical testing for provocative tests for carpal tunnel syndrome (Tinel's, Phalen's, Reverse Phalen's and carpal tunnel compression tests), blood check for secondary causes of carpal tunnel syndrome, nerve conduction testing as well ultrasonographic assessment of the carpal tunnel and median nerve.

Results

One-hundred and seventy-seven out of 232 (76.3%) had abnormal nerve conduction studies. Forearm symptoms and tenosynovitis confirmed by US examination were found in 51.3% of cases. No significant difference was found on comparing anthropometric measures in the affected hands to the control group hands. A higher prevalence of positive Phalen's and CT compression were found in patients suffering from tenosynovitis regardless of their nerve conduction study results. Sensitivity of Tinel's, Phalen's, Reverse Phalen's and carpal tunnel compression tests was higher for the diagnosis of tenosynovitis than for the diagnosis of CTS (Tinel, 46% vs. 30%; Phalen's, 92% vs. 47%; Reverse Phalen's, 75% vs. 42%; carpal tunnel compression test, 95% vs. 46%). Similarly, higher specificity of these tests was found with tenosynovitis than CTS.

Conclusion

The results of this study revealed that Tinel's, Phalen's, Reverse Phalen's and carpal tunnel compression tests are more sensitive, as well as being specific tests for the diagnosis of tenosynovitis of the flexor muscles of the hand, rather than being specific tests for carpal tunnel syndrome and can be used as an indicator for medical management of the condition.

Introduction

Carpal tunnel syndrome (CTS) is a common clinical condition with an estimated lifetime risk of 10% and an annual incidence of 0.1% among adults [1], [2]. These estimates are undoubtedly conservative because they are based on data collected prior to the substantial increase in work related cases of CTS in the 1980s and early 1990s and the concomitant increased awareness of this condition [3], [4]. More recent estimates of the prevalence of CTS in the general population are 0.6% in men and 5.8% in women [5]. Data from Sweden reported by Atroshi and colleagues suggest an overall prevalence of 2.1% [6]. Despite the large number of original research studies on carpal tunnel syndrome, considerable uncertainty and even controversy exist in the medical community about its extent and aetiology, the contribution of work and non-work risk factors to its development, the criteria used to diagnose it, the outcomes of various treatment methods and the appropriate strategies for intervention and prevention. In addition, there is insufficient evidence to identify a single “best” examination-based clinical test. Certain clinical tests have been in use as components of a clinical diagnosis of CTS, however, their sensitivity and specificity have been a matter of controversy [7]. Furthermore, it is relatively difficult for the treating physician to distinguish between CTS and other conditions with similar symptoms such as tendonitis. There is ample evidence that the accuracy of the available diagnostic tools is not very good [8], [9].

In recent years, imaging techniques such as magnetic resonance imaging [10], [11], [12], [13] and sonography [14], [15], [16], [17], [18], [19] have been shown to be of value in the diagnosis of CTS. Both have the advantage of providing insight into the possible focal causes of CTS such as localized space occupying lesions, rheumatoid arthritis, tenosynovitis or synovitis of the wrist [20], [21]. US and MRI enabled the researchers to assess the presence of tenosynovitis of the flexors of the hands or any other localized swelling [19]. However, no studies meeting the inclusion criteria addressed the frequency with which forearm conditions co-exist with CTS. This study was carried out to examine the relationship between the clinical manifestations of CTS as well as the possible related forearm conditions with the outcome of the diagnostic tools (nerve conduction tests and ultrasonography), and its implications for clinical practice.