Effect of a Bolus of Clonidine Systemically Administered on the Excitability of the Spinal Motoneurons of the Lower Extremity

The purpose of this study is to assess the effect of IV clonidine administration on lower limb spinal motoneuron excitability during standardized total intravenous anesthesia (propofol and remifentanil).

According to the literature data, intraoperative administration of clonidine reduces the need for morphine per and postoperative and thus reduces the side effects associated related to their administration. Nevertheless, on the basis of current knowledge, clonidine may disrupt some electrophysiological measures required for the intraoperative monitoring of surgeries with a high risk of neurological complications. For such surgery, anaesthesiologists are led to inject clonidine after surgery, at a time when the electrophysiological measures are no longer needed, which limits the benefit in terms of intraoperative morphine savings. Whith this study, investigators would like to investigate if an early administration of clonidine in patients aged 6 to 16 years undergoing ear surgery disturbs excitability of the spinal motor neuron. The choice of the study population is justified by the fact that the ear surgery does not require electrophysiological monitoring and it is carried out under conditions similar to that of anesthesia of scoliosis corrective surgery for which electrophysiological measurements are essential for the prevention of neurological complications. Observations will allow investigators to determine therefore whether early administration of clonidine is possible at high risk of neurological complications surgeries for which electrophysiological monitoring is essential.