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

Publication date: January 2018
Source:Clinical Neurophysiology, Volume 129, Issue 1
Author(s): Christoph Czarnetzki, André Truffert, Abdelhafid Mekideche, Antoine Poncet, Christopher Lysakowski, Martin R. Tramèr, Michel R. Magistris
ObjectiveTo 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.MethodsIn 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.ResultsResponses 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.ConclusionsMaximal contraction response to muscle percussion has a muscular rather than a neural origin. However, percussion also excites axons within the muscle.SignificanceThese findings may provide clues to understand the changes observed in neuromuscular disorders.



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