Neurophysiological and paraspinal oximetry monitoring to detect spinal cord ischemia in patients during and after descending aortic repair: An international multicenter explorative study.

BACKGROUND: During descending aortic repair, critically decreased blood flow to the myelum can result in ischemic spinal cord injury and transient or permanent paraplegia. Assessment of motor evoked potentials (MEPs) has been shown to be a valuable tool which allows to detect spinal cord ischemia (SCI) intraoperatively within a therapeutic window suitable to prevent progression to paraparesis or paraplegia. MEP monitoring is not feasible during postoperative care in the awakening patient. Therefore, ancillary techniques to monitor integrity of spinal cord function are needed to detect delayed spinal cord ischemia. OBJECTIVE: The purpose of this study is to evaluate whether assessment of long loop reflexes (LLR; F-waves) and paraspinal muscle oximetry using Near-Infrared Spectroscopy (NIRS) are feasible and valid in detecting delayed SCI. METHODS: We aim to include patients from three tertiary referral centers undergoing aortic repair with MEP monitoring in this study.F-wave measurements and paraspinal NIRS oximetry will be operated intra- and postoperatively. Measurement characteristics and feasibility will be assessed in the first 25 patients. Subsequently, a second cohort of 75 patients will be investigated to determine the sensitivity and specificity of F-waves and NIRS in detecting perioperative SCI. In this context for the MEP group SCI is defined intraoperatively as significant MEP changes and postoperatively as newly developed paraplegia. CONCLUSIONS: A clinical study design and protocol is proposed to assess if F-waves and/or NIRS-based paraspinal oximetry are feasible and valid in detecting and monitoring for occurrences of delayed SCI.

Preterm Perinatal Hypoxia-Ischemia Does not Affect Somatosensory Evoked Potentials in Adult Rats.

Somatosensory evoked potentials (SSEPs) are a valuable tool to assess functional integrity of the somatosensory pathways and for the prediction of sensorimotor outcome in perinatal injuries, such as perinatal hypoxia-ischemia (HI). In the present research, we studied the translational potential of SSEPs together with sensory function in the male adult rat with perinatal HI compared to the male healthy adult rat. Both somatosensory response and evoked potential were measured at 10-11 months after global perinatal HI. Clear evoked potentials were obtained, but there were no group differences in the amplitude or latency of the evoked potentials of the preceding sensory response. The bilateral tactile stimulation test was also normal in both groups. This lack of effect may be ascribed to the late age-of-testing and functional recovery of the rats.

Anterior Transthoracic Surgery with Motor Evoked Potential Monitoring for High-Risk Thoracic Disc Herniations: Technique and Results.

OBJECTIVE: To present our experience with anterior transthoracic surgery for high-risk thoracic disc herniations (TDHs) using motor evoked potential monitoring (MEPm). METHODS: We estimated surgical risk based on clinical and radiologic characteristics, including anteroposterior (AP) spinal canal occupation (SCO), AP spinal cord compression (SCC), residual AP spinal cord diameter (RSCD), and intramedullary signal changes (ISC). We analyzed Anand, ASIA, and Nurick scores, anesthesiologic, neurophysiological, and surgical reports. We considered >50% MEP signal deterioration significant. RESULTS: Out of 435 anterior transthoracic procedures, 77 concerned high-risk TDH(s): 69 single-level, 8 multilevel, 61 with clinical myelopathy, 6 with merely ISC. Mean SCO and SCC were 55.4% and 54.0% for single-level, 31.8% and 33.9% for multilevel cases. ISC were present in 64% of single-level and 50% of multilevel cases, calcifications in 87% of single-level and 84% of multilevel TDHs. We initially performed 23 mini-transthoracic approaches (mini-TTAs) and 24 thoracoscopic microdiscectomies (TMDs), more recently 29 TMDs (23 giant TDHs) and 1 transaxillary mini-TTA. Overall, 72 patients had reliable MEP signals. Isolated lower extremity MEP signal deteriorations (n = 21) correlated with maximal TDH AP diameter, SCO, SCC, and ISC. ASIA and Nurick scores improved in 45% and 66% respectively. One patient became paraplegic. MEP signal deterioration had 100% sensitivity, 75% specificity, and 19% positive predictive value during and 44% at the end of surgery. CONCLUSIONS: Maximal TDH AP diameter, SCO, SCC, (sub)total calcification, and ISC correlate with lower extremity MEP signal deterioration. In experienced hands, TMD with MEPm support is a safe, efficient procedure for high-risk TDHs.