Current opinions and recommendations on multimodal intraoperative monitoring during spine surgeries

Abstract

With the rapid development of imaging techniques and better understanding of structural and functional pathology of the spine and spinal cord there has been a worldwide increase in the number of spine surgeries performed, particularly in specialized interdisciplinary spine centers. In addition to the congenital and acquired deformities of the spine and relatively rare spinal cord tumors, common degenerative spine disease within the aging general population contributes to a growing number of pathologies with myelopathies. This is important because antecedent myelopathy increases spinal cord risk during surgical treatment. The possibility of having functional neurophysiological assessment during spine and spinal cord surgery was introduced in 1970s by applying somatosensory evoked potentials (SEPs) as well as spinal evoked potentials [15, 21, 32, 33]. Meanwhile these modalities and continuous EMG recording have been enhanced by the addition of corticospinal motor pathway monitoring through the use of motor evoked potentials (MEPs) elicited by transcranial electrical stimulation [3]. The application of multimodal intraoperative monitoring (MIOM) became routine in several spine centers, being documented by publications about the specificity and sensitivity as well as clinical experience and outcome measurements during different spinal surgical procedures [6, 9, 13, 14, 17, 22, 24, 26, 27]. In this supplement on intraoperative monitoring the Spine Center of the Schulthess Clinic presents their experience with the application of MIOM during spine surgery analyzing 1,017 operations in the years 2000–2005. The patients for monitoring were selected out of 11,356 who received spine surgery at the institution during the study period. The indication for each monitoring procedure was discussed and established within the monitoring and surgical team. The detailed analysis of this large patient population resulted in a sensitivity of 89% and specificity of 99%. Sutter et al. [31] conclude that MIOM is an effective method of monitoring the spinal cord functional integrity during spine surgery and therefore can lead to reduction of neurological deficits and consequently improve postoperative results. An independent series of 206 thoracolumbar surgeries also presented in this supplement supports this conclusion [19]. Sala et al. [27] discussed in their recent publication of a historical control study the ethical limitation for performing prospective randomized studies to assess the efficacy of MIOM while clearly documenting that monitoring improves outcome after surgery for intramedullary spinal tumors. The Spine Society of Europe (SSE) supported the development of MIOM by presentations of the results at its annual meetings and organized workshops to stimulate discussion and communication between the spine surgeons and clinical neuroscientists. The SSE has also introduced quality control management in spine surgeries by establishing Spine Tango, a web-based international registry that includes MIOM documentation (http://www.eurospine.org). Other international spine societies such as Scoliosis Research Society presented several original papers on MIOM at the 41st annual meeting in 2006 [2, 5, 23] illustrating its advantages for surgery of adolescent idiopathic and infantile scoliosis. Recently, the International Society of Intraoperative Neurophysiology (ISIN) was founded to stimulate interdisciplinary communication and collaboration between surgeons, neurologists, neurophysiologists and anesthetists (http://www.ptsroma.it/isin). The aim of a first consensus meeting on intraoperative monitoring during spine surgeries in Verona (28 September 2006) was to provide recommendations for the improvement and appropriate application of monitoring techniques during spine surgeries. Experts in the field were invited for a meeting with the support of the European Spine Journal (Max Aebi, MD, Editor-in-chief, Marek Szpalski, MD, Supplement Editor) to summarize the current state-of-the-art and prepare current opinions and recommendations. This consensus statement represents a work in progress and as with all other recommendations or proposals, it must be updated as new information is gained.