Somatosensory evoked potentials to muscle percussion in humans: upper extremity

Cortical as well as presumably subcortical potentials were recorded from 20 normal subjects in response to mechanical percussion of the thenar eminence. Nuchal-to-frontal recordings detected an initial negative component at 21 msec, followed by positivities at 29 and 36 msec. C-prime to frontal recordings produced prominent positivities at 29 and 44 msec. Recordings over the peripheral nerve did not reveal consistent potentials. Control experiments indicate that potentials are initiated by fast-adapting muscle receptors. If additional control experiments continue to support these findings, yet another constituent of electrically evoked somatosensory potentials--which may prove useful in the definition of muscle innervation disorders--will have been identified.