Motor evoked potentials facilitated by an additional peripheral nerve stimulation.
In order to explore the use of intraoperative monitoring of motor systems under general anesthesia, the effect of transcutaneous electric brain stimulation was examined by non-invasive muscle activity recording. The mechanisms of anesthetic suppression of myogenic responses as well as different concepts to circumvent this suppression are reviewed. Facilitation of cortical stimulation effect at the spinal level was attempted by adding a well-timed peripheral nerve stimulation to it, similar to that for H-reflex from M. flexor carpi radialis. Eight comatose patients from the intensive care unit and 17 patients under general anesthesia were examined. Spinal motoneuron excitability changes caused by cortical stimulation in anesthetized patients showed a monophasic facilitation pattern with lower facilitation degree and shorter duration, compared to non-anesthetized patients. The latter showed a long-lasting, three-phase pattern of excitability change. Before there can be any clinical application of this facilitation technique, however, two problems remain to be solved: achieving a stable motoneuron conditioning level throughout anesthesia, and making the application of a compatible technique in more muscles possible.
Taniguchi
M
M
Neurosurgical Clinic, University of Bonn, F.R.G.
Schramm
J
J
D000758:Anesthesia; D002540:Cerebral Cortex / Q000502:physiology*; D003128:Coma / Q000503:physiopathology; D005071:Evoked Potentials / Q000502:physiology*; D006181:H-Reflex / Q000502:physiology; D006801:Humans; D008280:Magnetics; D009043:Motor Activity / Q000502:physiology*; D009132:Muscles / Q000502:physiology*; D010525:Peripheral Nerves / Q000502:physiology*; D013116:Spinal Cord / Q000502:physiology