P285 Postoperative clinical motor findings correlations with IONM MEP results during intramedullary spinal cord tumor removal. Presentation of 2 cases

• Published in: Clinical neurophysiology 2017-09, Vol.128 (9), p.e269-e269
• Main Authors: Montes-Peña, Vizmary, Tramontano, Vincenzo, Sala, Francesco, Soda, Christian
• Format: Article
• Language: English
• Subjects: D-wave; Intramedullary tumors; Motor evoked potentials; Spinal-cord monitoring; Transient paraplegia; Transient quadriplegia
• ISSN: 1388-2457; 1872-8952
• DOI: 10.1016/j.clinph.2017.07.293

Description of two cases of IONM in intramedullary spinal cord tumors muscle MEPs and D-wave recordings, and its immediate postoperative outcomes correlation. Muscle MEPs, D-wave and SSEPs were recorded in both patients. D-wave amplitude and muscle MEPs presence-absence, were the critical parameters for MEP interpretation. Case 1. A 64-year-old male presented with a history of progressive tingling paresthesia with clumsiness to fine movements in both hands. A cervical MRI scan revealed a lesion from C3–C4 level, compatible with ependymoma. During surgery, loss of muscle MEPs in the left TA, significantly decreasing MEPs in right and left AH, right TA, left APB and EXT and slightly decreasing MEPs in right APB and EXT, occurred. D-wave amplitude showed no change. Postoperatively, the patient had a transient quadriplegia, as expected from MEP data. After a week, he was able to reach the vertical position with some help. Case 2. A 61-year-old male presented with a history of dysesthesias and tingling sensation of lower extremities, causing the patient to fall. Weakness for right hand movementsA cervical-dorsal MRI study revealed a lesion from C6-T1 level, compatible with an ependymoma. During surgery, right leg muscle MEPs completely disappeared, and right leg MEPs significantly decreased. Muscle MEPs in right EXT slightly decreased. A drop of D-wave amplitude of about 40% was noted. After surgery, the patient had a transient paraplegia. In the following days, there was a bilateral improvement of paraparesis. Intraoperative loss of muscle MEPs as long as D-wave remains above 50% of the baseline value, indicates a temporary loss of motor function in the corresponding limb. Further D-wave amplitude declining will translate in permanent plegia. Correct prediction of the clinical status during surgery is possible with a high certainty. Muscle MEPs, combined with D-wave amplitude recordings, provides useful intraoperative information and correctly correlate with postoperative recovery. Using this information, surgical strategy can be adapted before irreversible neurological damage is caused. Present and stable IONM recordings allow complete resection of intramedullary tumors with confidence about the integrity of the motor pathways.