Proximal stimulus confirms carpal tunnel syndrome--a new test? --a clinical and electrophysiologic, multiple-blind, controlled study

J Clin Neurophysiol. 2012 Feb;29(1):89-95. doi: 10.1097/WNP.0b013e318246b87d.


Purpose: In patients with carpal tunnel syndrome (CTS), a proximal stimulus can sometimes evoke typical symptoms. Explanations for this phenomenon include local disturbance of arterial circulation, stimulation of trigger points, and the double crush syndrome (DCS). The aim of this study was to investigate the value of these hypotheses with a new provocation test performed on the infraspinatus muscle (infraspinatus test [IsT]) in a multiple-blind, controlled study.

Methods: Thirty-four subjects were recruited, tested with IsT, and measured with nerve conduction velocity (NCV). Additionally, the Tinel sign (TS) was examined. The McNemar test was used to compare the IsT and NCV with the subjects' symptoms. The Fisher exact test was used to correlate IsT and symptoms.

Results: In the McNemar test, IsT showed no significant difference to the NCV (P = 0.18, sensitivity: 69.7%, specificity: 87.1%) regarding the subjects' symptoms (P = 0.2888, sensitivity 80.6%, specificity 93.9%). The Fisher exact test proved the significance of the IsT with regard to symptoms (P < 0.0001).

Conclusions: Pressure exerted on a certain point of the infraspinatus muscle has significant diagnostic power and may be a valuable clinical test in everyday practice. We discuss the arguments for and against a new, latent trigger point and whether other mechanisms may play a role.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / physiology
  • Adult
  • Aged
  • Aged, 80 and over
  • Carpal Tunnel Syndrome / diagnosis*
  • Carpal Tunnel Syndrome / physiopathology
  • Double-Blind Method
  • Female
  • Humans
  • Male
  • Median Nerve / physiopathology*
  • Middle Aged
  • Myofascial Pain Syndromes / diagnosis*
  • Myofascial Pain Syndromes / physiopathology
  • Neural Conduction / physiology*
  • Sensitivity and Specificity
  • Trigger Points / physiopathology*