Intraoperative Neurophysiology During Intramedullary Spinal Cord Tumor Surgery

Intramedullary spinal cord surgery is a particularly challenging field due to the delicate balance between the aim to remove a harmful lesion and the need to preserve the healthy, functional tissue in which the lesion is growing. Over the decades, a spectrum of techniques with the scope to monitor sensory and motor functions during a surgical operation, hence maximizing resection while minimizing damage to the surrounding nervous tissue, have been developed. These techniques are known as intraoperative neurophysiological monitoring (IONM) and the most common include somatosensory-evoked potentials (SSEPs), transcranial motor-evoked potentials (TcMEPs), free running electromyography (EMG), and D wave monitoring. Along with these, mapping techniques to localize specific functions in the spinal cord can be employed, such as dorsal columns and cortico-spinal tract mapping. The ever-growing experience in using these techniques allowed the development of warning criteria that are currently used in a context of teamwork and efficient communication within the OR team in order to optimize surgical strategy and patient outcomes.