Spinal tumor (ST) surgery carries the risk of new neurological deficits in the postoperative period. Intraoperative neurophysiological monitoring and mapping (IONM) represents an effective method of identifying and monitoring in real time the functional integrity of both the spinal cord (SC) and the nerve roots (NRs). Despite consensus favoring the use of IONM in ST surgery, in this era of evidence-based medicine, there is still a need to demonstrate the effective role of IONM in ST surgery in achieving an oncological cure, optimizing patient safety, and considering medicolegal aspects. Thus, neurosurgeons are asked to establish which techniques are considered indispensable. In the present study, the authors focused on the rationale for and the accuracy (sensitivity, specificity, and positive and negative predictive values) of IONM in ST surgery in light of more recent evidence in the literature, with specific emphasis on the role of IONM in reducing the incidence of postoperative neurological deficits. This review confirms the role of IONM as a useful tool in the workup for ST surgery. Individual monitoring and mapping techniques are clearly not sufficient to account for the complex function of the SC and NRs. Conversely, multimodal IONM is highly sensitive and specific for anticipating neurological injury during ST surgery and represents an important tool for preserving neuronal structures and achieving an optimal postoperative functional outcome.
Antonino Scibilia, Carmen Terranova, Vincenzo Rizzo, Giovanni Raffa, Adolfo Morelli, Felice Esposito, Raffaella Mallamace, Gaetano Buda, Alfredo Conti, Angelo Quartarone and Antonino Germanò
Alfredo Conti, Antonio Pontoriero, Giuseppe K. Ricciardi, Francesca Granata, Sergio Vinci, Filippo F. Angileri, Stefano Pergolizzi, Concetta Alafaci, Vincenzo Rizzo, Angelo Quartarone, Antonino Germanò, Roberto Israel Foroni, Costantino De Renzis and Francesco Tomasello
The integration of state-of-the-art neuroimaging into treatment planning may increase the therapeutic potential of stereotactic radiosurgery. Functional neuroimaging, including functional MRI, navigated brain stimulation, and diffusion tensor imaging–based tractography, may guide the orientation of radiation beams to decrease the dose to critical cortical and subcortical areas. The authors describe their method of integrating functional neuroimaging technology into radiosurgical treatment planning using the CyberKnife radiosurgery system.
The records of all patients who had undergone radiosurgery for brain lesions at the CyberKnife Center of the University of Messina, Italy, between July 2010 and July 2012 were analyzed. Among patients with brain lesions in critical areas, treatment planning with the integration of functional neuroimaging was performed in 25 patients. Morphological and functional imaging data sets were coregistered using the Multiplan dedicated treatment planning system. Treatment planning was initially based on morphological data; radiation dose distribution was then corrected in relation to the functionally relevant cortical and subcortical areas. The change in radiation dose distribution was then calculated.
The data sets could be easily and reliably integrated into the Cyberknife treatment planning. Using an inverse planning algorithm, the authors achieved an average 17% reduction in the radiation dose to functional areas. Further gain in terms of dose sparing compromised other important treatment parameters, including target coverage, conformality index, and number of monitor units. No neurological deficit due to radiation was recorded at the short-term follow-up.
Radiosurgery treatments rely on the quality of neuroimaging. The integration of functional data allows a reduction in radiation doses to functional organs at risk, including critical cortical areas, subcortical tracts, and vascular structures. The relative simplicity of integrating functional neuroimaging into radiosurgery warrants further research to implement, standardize, and identify the limits of this procedure.