[Intraoperative neurophysiological monitoring: methods in neurosurgery]

IONM uses different neurophysiological techniques during surgery time, thus avoiding possible lesions to the neurological structures, making surgery safer and better. We describe two types of IONM: mapping techniques and monitoring techniques, as well as their advantages, disadvantages and complications. We look into the more useful techniques in this field, as well as providing orientation about its use according to the surgical areas and the neurological structures under risk. In conclusion, we affirm that IONM is one of the most important advances in modern neurosurgery.