Scratch Collapse Test for Carpal Tunnel Syndrome: A Systematic Review and Meta-analysis

Abstract

Background:Despite the fact that carpal tunnel syndrome (CTS) is the most common entrapment neuropathy, the diagnostic accuracy of clinical screening examinations for CTS is controversial. The scratch collapse test (SCT) is a novel test that may be of diagnostic advantage. The purpose of our study was to determine the diagnostic accuracy of the SCT for CTS.Methods:A literature search was performed using PubMed (1966 to April 2018); Ovid MEDLINE (1966 to April 2018); EMBASE (1988 to April 2018); and Cochrane Central Register of Controlled Trials (The Cochrane Library, to April 2018). We examined the studies for the pooled sensitivity, specificity, and likelihood ratios of the SCT. This review has been registered with PROSPERO (CRD42018077115).Results:The literature search generated 13 unique articles. Seven articles were included for full text screening and 3 articles met our inclusion criteria, all of which were level II evidence with low risk of bias (165 patients). Pooled sensitivities, specificities, positive likelihood ratio, and negative likelihood ratios were 0.32 [95% CI (0.24–0.41)], 0.62 [95% CI (0.45–0.78)], 0.75 [95% CI (0.33–1.67)], and 1.03 [95% CI (0.61–1.74)], respectively. The calculated area under the summary receiver operating characteristic (AUSROC) curve was 0.25, indicating a low diagnostic accuracy.Conclusion:The SCT has poor sensitivity; however, it is moderately specific. Based on the current literature and their variable quality of the evidence, we conclude that the SCT is not an adequate screening test for detecting CTS.

Patient-Reported Outcomes and Provocative Testing in Peripheral Nerve Injury and Recovery

“…27 28 Multiple reports have challenged the proposed mechanism of action utilized by SCT—the cutaneous silent period (CuSP). 28 The CuSP is described as a transient decrease in EMG activity observed after a noxious stimulus of a nerve. 28 Some studies have shown that the CuSP was prolonged in moderate CTS patients, but absent in severe CTS patients.…”

Evaluation of different physical examination methods for the diagnosis of carpal tunnel syndrome

“…In previous studies on the application of SCT for the diagnosis pf CTS, Cheng et al (16) reported a sensitivity and specificity of 0.69 and 0.99 in 228 cases, Gillenwater et al (21) reported 0.77 and 0.99 in 24 cases, Huynh et al (22) performed a meta-analysis of Blok et al (23), Makanji et al (24) and Simon (25) et al who reported a sensitivity and specificity of 0.32 and 1.00 in 37 cases, 0.34 and 0.61 in 88 cases, and 0.28 and 0.38 in 40 cases, respectively . The sensitivity and specificity reported by Montgomery et al (26) were 0.07-0.15 and 0.78-0.87 in 92 cases, respectively.…”

Validity of Using the Scratch Collapse Test in the Lower Extremities

“…trained with Dr. Mackinnon, the original promoter of the scratch collapse test and senior author of the 2008 article by Cheng et al 23 The learning curve in performing the scratch collapse test has been recognized in several studies, but given our examiner's prior experience and frequent application of the test in practice, it likely played an important role in our results. [5][6][7]23,26 When performing the scratch collapse test, the examiner should be thoroughly versed in nerve topographic anatomy and common areas of nerve compression, as inaccurate or wide cutaneous stimulation could lead to varying results. [3][4][5]7 This idea is supported by the positive results reported by the original senior author for peroneal nerve compression, and the wide range of sensitivities when performed by novice examiners.…”