Spinal Mapping for Tumor Surgery: An Overview of Relevant Modalities, Clinical Impact, and Future Directions

Abstract

Intramedullary spinal cord tumor surgery demands precise intraoperative strategies to preserve neurological function while achieving maximal resection. Neurophysiological monitoring and direct spinal cord mapping have emerged as essential tools for guiding surgeons through these complex procedures by providing both functional and anatomical insight. This project examines the complementary contributions of somatosensory evoked potentials (SSEPs), motor evoked potentials (MEPs), D-waves, electromyography (EMG), train-of-four (TOF) monitoring, and direct cord mapping (DCM) during intramedullary tumor resection. Each modality offers distinct clinical value. SSEPs assess dorsal column sensory pathway integrity and help identify early ischemic or traction-related changes during surgical manipulation. MEPs and D-waves evaluate the functional status of the corticospinal tract and provide rapid detection of motor pathway compromise, with D-waves serving as a strong predictor of long-term postoperative motor outcomes. EMG detects nerve root irritation or mechanical stress, particularly relevant for cauda equina involvement, while TOF monitoring ensures adequate neuromuscular conditions for reliable motor and electromyography responses. DCM enhances anatomical accuracy by identifying the physiological midline and guiding safe myelotomy planning in cases where normal landmarks are distorted. Integration of these modalities creates a comprehensive monitoring framework that combines continuous functional assessment with precise anatomical localization. This multimodal approach allows early recognition of reversible changes, improves communication between surgical and neurophysiological teams, and supports timely intraoperative adjustments to protect critical pathways. The combined use of mapping and monitoring has been associated with improved sensory and motor outcomes by helping surgeons balance the goal of maximal tumor resection with the imperative of neurological preservation. This study highlights that incorporating multiple neurophysiological modalities offers the most robust safety and guidance system for intramedullary spinal cord tumor surgery. The complementary nature of these techniques underscores their importance in modern spinal oncology and supports continued advancement of multimodal intraoperative monitoring practices.