The diagnosis of common peroneal nerve entrapment neuropathy (CPNEN) is based on clinical symptoms and nerve conduction studies. However, nerve conduction studies may not detect abnormalities. Under the hypothesis that repetitive plantar flexion that loads the peroneal nerve (PN) at the entrapment point without lumbar loading would be a useful CPNEN provocation test, we evaluated the repetitive plantar flexion (RPF) test as an adjunct diagnostic tool for CPNEN. The study design was a retrospective analysis of prospectively collected data.
Our study population consisted of 18 consecutive patients whose ipsilateral CPNEN improved significantly after PN neurolysis. Using repetitive ankle plantar flexion as a CPNEN provocation test, results were recorded as positive when it elicited numbness and/or pain in the affected area of the PN.
The RPF test induced symptoms on all affected sides in the course of 57.4 seconds (range, 14-120 seconds). In 3 patients it induced numbness in the affected area of the PN in the normal leg. Receiver operating characteristic analysis showed that the diagnostic sensitivity and accuracy of the test were 94.4% each. The suggested cutoff point was 110 seconds and the area under the receiver operating characteristic curve was 0.97 (95% confidence interval 0.93-1.02). The positive and the negative predictive values were 89.5% and 94.1%, respectively.
Our simple RPF test elicited the symptoms of CPNEN and our provocation test helped to identify dynamic PN entrapment neuropathy as the origin of intermittent claudication.