Contraction response to muscle percussion: A reappraisal of the mechanism of this bedside test

A randomized, placebo-controlled study. Published in the European Journal of Pain, a multi-disciplinary, international journal that aims to be a global forum on all aspects of pain research and pain management.

Christoph Czarnetzki; André Truffert; Abdelhafid Mekideche; Antoine Poncet;

Christopher Lysakowski; Martin R. Tramèr; Michel R. Magistris

Clinical Neurophysiology. Volume 129, Issue 1, January 2018, Pages 51-58. DOI: 10.1016/j.clinph.2017.10.013

Highlights

• We studied the contraction evoked by hammer percussion of muscle in healthy humans.

• Contraction evoked by muscle percussion stems from direct excitation of the muscle.

• Muscle percussion also excites motor axons within the muscle.

Abstract

Objective To study whether the contraction evoked by muscle percussion stems from the excitation of the muscle or of the nerve and to discuss the changes of this response in neuromuscular disorders.

Methods In 30 neurologically healthy patients undergoing surgery (for ear, nose, or throat problems unrelated to the study) under general anesthesia with propofol and sufentanil we measured with an electrogoniometer the maximal dorsiflexion of the ankle evoked by reflex hammer percussion of the tibialis anterior muscle before and under neuromuscular junction blockade with rocuronium bromide. In 3 additional healthy volunteers we searched for F-waves to disclose whether percussion excites axons within the muscle.

Results Responses from 28 neurologically healthy patients (15 women) were analyzed after exclusion of 2 due to technical problems. Mean age (SD) was 28 (9) years. Maximal dorsiflexion of the ankle was not significantly modified by neuromuscular junction blockade (mean difference 0.01 mV [95%CI, −0.07 to 0.08], p = 0.879). Muscle percussion evoked F-waves in the 3 healthy volunteers tested.

Conclusions Maximal contraction response to muscle percussion has a muscular rather than a neural origin. However, percussion also excites axons within the muscle.

Significance These findings may provide clues to understand the changes observed in neuromuscular disorders.