Assessing the accuracy of ultrasound compared to magnetic resonance imaging for the diagnosis of carpal tunnel syndrome: a structured literature review

Abstract

Abstract Background: Carpal tunnel syndrome is a highly prevalent and function-limiting condition that predominantly affects adults who engage in manual repetitive tasks and as a result of population growth and increases in manual labour, the incidence has gradually increased, worldwide. Aim and objectives: The diagnosis of carpal tunnel syndrome can be challenging due to insidious presentations and the number of differential diagnoses that can mimic the condition and thus, accuracy relies upon imaging and nerve conduction studies, although in recent times, it has become unclear whether ultrasound or magnetic resonance imaging offers the most desirable accuracy. This structured literature review sought to address this problem. Method: A search of the literature was undertaken using PubMed, EMBASE and Academic Search and studies were restricted to publication in the last five years and English language. Quality was assessed using QUADAS-2 and the diagnostic accuracy outcomes were analysed narratively. A total of 14 studies were eligible for inclusion and the quality was predominantly poor due to a high risk of bias related to the cross-sectional, retrospective and case-control designs. Result: The accuracy outcomes showed that ultrasound and MRI provided comparable sensitivities and specificities for diagnosing CTS, although differences were observed when different threshold criteria were employed. For MRI, the sensitivity and specificity for CTS using apparent diffusion coefficients at the median nerve of <1.1 were 91.3-100% and 76.3-100%, respectively, whilst the respective indices for ultrasound based on a cross-sectional area of 12mm2 for the median nerve were 92% and 94%. Conclusion: In light of these findings, it was recommended that ultrasound be used as the first-line imaging test and as a potential replacement for nerve conduction studies not only due to its high accuracy for CTS but also as it is associated with fewer operational limitations, than MRI. Given the limitations of this review, it is imperative that future research continues to explore the best means to diagnosing CTS through considering the recommendations defined herein.