ANTERIOR NECK RECORDING OF INTRAOPERATIVE SOMATOSENSORY-EVOKED POTENTIALS IN CHILDREN

Study Design. The authors have developed technique of using anterior n eck derivations to record posterior tibial nerve N28 during operative somatosensory-evoked potential monitoring. Objective. this prospective study of 10 patients compared the ease of application of electrodes a nd stability of waveforms with ''traditional'' posterior neck recordin gs. Summary of background Data. Somatosensory-evoked potential monitor ing has been used in children since the 1980s. A number of important f actors, patient related and technical,are unique to this age group, wh ich can cause difficulty with execution and interpretation. A major pa tient-related problem is unreliability of the cortical response in som atosensory-evoked potential monitoring because of the effect of inhala tion anesthesia. This has been described as occurring more often in th e pediatric group, perhaps because of the continuing maturation of the complex somatosensory system. Thus, the authors have relied heavily o n the cervical potential to monitor spinal cord integrity. Recording t he cervical response using the traditional ''posterior'' montage may b e technically impossible if the electrodes lie within the operative fi eld. Methods. Posterior tibial somatosensory-evoked potentials were pe rformed according to the guidelines of the American Electroencephalogr aphic Society. Additional recordings were obtained from two anterior n eck sites. Multiple reference electrodes were used to evaluate which m ontage rendered the most reliable wave-form. Results. Optimal montage for recording an anterior neck potential was cricoid cartilage-Cz'. Th ere were no significant differences in the onset latency or peak ampli tudes between the anterior and posterior cervical recordings. Conclusi ons. The anterior neck derivation was found to be an acceptable adjunc t to posterior montages, being stable, of comparable latency, and of s table amplitude. Electrodes are easier to apply, less invasive than na sopharyngeal or esophageal electrodes. This technique allows one to ex amine patients who previously could not be monitored.