Sensitivity and specificity of the sensory collapse test for nerve entrapment syndrome in the upper extremity

Several prospective blinded studies have found poorer sensitivity for the sensory collapse test than reported by Susan E Mackinnon's team. However, the blinded examiner had no knowledge of the patient's clinical presentation, or even of the purpose of the test. In these conditions, it seems difficult to perform the sensory collapse test correctly. The aim of the present study was to evaluate the efficacy of the sensory collapse test in the diagnosis of nerve compression in the upper extremity, using a trained, "partially" blinded examiner, with a minimum of clinical information in order to avoid bias due to poor execution of the test, while still unable to influence the test result.

Seventy-two patients with diagnosis of nerve entrapment in the upper extremity were included prospectively. The sensory collapse test was performed by two examiners, one of whom was blinded to laterality and to the site of nerve compression, aware only of the affected nerve. Using electrodiagnosis study as reference, the sensitivity and specificity of the sensory collapse test were calculated for each examiner.

The unblinded examiner showed 72% sensitivity and 57% specificity, and the blinded 68% sensitivity and 57% specificity.

The sensory collapse test is useful for diagnosis of nerve entrapment in the upper limb, even with a blinded examiner.