Monitoring Of Spinal Cord Function Research Articles

Dermatomal somatosensory evoked potentials and cortical somatosensory evoked potentials assessment in congenital scoliosis

BackgroundThe aim of this study was to assess the value of dermatomal somatosensory evoked potentials (DSEPs) and cortical somatosensory evoked potentials (SSEPs) in monitoring spinal cord function for patients with congenital scoliosis (CS).MethodsThis retrospective study reviewed the medical records of patients (n = 102) who underwent DSEP (T2-S1 dermatome), of whom 60 were normal subjects and 62 with congenital scoliosis. The study analyzed the latencies and peaks of N1-L, N1-R, P1-L and P1-R recorded by DSEPs of patients’ thoracolumbar dermatomes. To observe the incidence of abnormal DSEPs and SSEPs in CS patients and to analyze the difference in sensitivity and reliability between the two in the examination of scoliosis patients. SPSS 22.0 statistical software package was used to analyze the data, and χ2 test and correlation analysis were used to indicate that the difference was statistically significant, p < 0.05.ResultsSixty two patients with CS were evaluated with total spine magnetic resonance imaging (MRI). Only 23 patients (37.09%) showed spinal cord malformations in the MRI findings. The DSEP recordings showed a relatively high sensitivity (97.8%) compared to the abnormality rate of SSEPs recordings, and the rates of waveform, latency and amplitude abnormalities were much higher in DSEPs recordings (36.6, 36.3, 24.8%) than in SSEPs recordings (3.2, 22.5, 14.5%). The abnormality rate of DSEP records with and without neurological symptoms was higher than the abnormality rate of SSEP records (100% vs 20, 96.2% vs 44.2%, p<0.05). And in 62 patients with CS, the rate of positive MRI (37.1%) was lower than that recorded by DSEP (79.6% / 57.9%). p < 0.05.ConclusionDSEPs are more sensitive to microscopic posterior column dysfunction in patients with CS that cannot be detected by either radiology or routine clinical examination. Preoperative DSEPs assessment is recommended as a baseline examination for intraoperative monitoring and comparison with the postoperative situation. DSEPs recording complements the information obtained from routine clinical and radiological evaluation.

An Hourglass-Type Spinal Schwannoma Spreading to the Chest Treated with One-Stage Total Removal through Posterior Paravertebral Approach without Opening the Pleural Cavity (Clinical Observation)

The article describes the treatment of a 20-year-old patient with a spinal hourglass schwannoma (neurinoma) in the thoracic spine, growing from the right Th3 spinal root, spreading into the thoracic cavity and compressing the apex of the right lung. The introduction presents the frequency of occurrence of such neoplasms among all spinal cord tumors. Complaints, neurological symptoms, neoplasm diagnosis methods and its clinical and radiological manifestations are presented. The article describes stages and techniques of total surgical removal of the spinal hourglass schwannoma through the posterior paravertebral minimally invasive approach without opening the pleural cavity and with using neurophysiological monitoring of spinal cord function performed at the Neurosurgical Clinic of the Novosibirsk Research Institute of Traumatology and Orthopaedics named after Ya.L. Tsivyan. The data of histological examination and MRI control in the early postoperative period are presented. The follow-up was carried out at 6 and 12 months after surgical treatment. The publications describing the surgical treatment of paravertebral tumors through different approaches, the technique of their removal, possible complications and methods of their prevention are analyzed, and the classification according to Eden (1941), which characterizes the type of tumor growth, is presented.

Neurophysiological monitoring of spinal cord function during spinal deformity surgery: 2020 SRS neuromonitoring information statement.

The Scoliosis Research Society has developed an updated information statement on intraoperative neurophysiological monitoring of spinal cord function during spinal deformity surgery. The statement reviews the risks of spinal cord compromise associated with spinal deformity surgery; the statement then discusses the various modalities that are available to monitor the spinal cord, including somatosensory-evoked potentials, motor-evoked potentials, and electromyographic (EMG) options. Anesthesia considerations, the importance of a thoughtful team approach to successful monitoring, and the utility of checklists are also discussed. Finally, the statement expresses the opinion that utilization of intraoperative neurophysiological spinal cord monitoring in spinal deformity surgery is the standard of care when the spinal cord is at risk.

Anaesthetic Management of Paediatric Patients Undergoing Scoliosis Surgery in Camp

BACKGROUND: Scoliosis is most commonly idiopathic in origin, but it may be congenital or secondary to neuromuscular disease, trauma, infection or neoplasm. Aim: Aims of surgery is to correct the curvature, improve posture and reduce progression of respiratory dysfunction.Objectives: Perioperative challenges for anaesthetist in scoliotic surgery are to avoid hypothermia, hemodynamic stability, spinal cord monitoring, positioning, induced hypotension, major blood loss, postoperative pain management and intensive care management of patient. Material and method: After taking parenteral consent, 15 paediatric patient’s data were collected who underwent scoliotic correction surgery over 12 days from 1st to 12th January of 2019. Result:Children underwent posterior fusion scoliosis surgery aged (11.2 ± 2.3) years. surgical duration and blood loss were (7.5 ±1.5) hours, (856 ±235) ml respectively. patients were shifted to ICU because of prolonged procedure and major fluid shift. Conclusion: Cardio-respiratory dysfunction may exist as a result of progressive scoliosis or related to coexisting disease, therefore careful preoperative assessment is required. Intraoperative considerations include the prone position, avoiding hypothermia, minimizing blood loss and monitoring spinal cord function. Good postoperative pain control is essential and requires a multimodal approach.

The Recognition, Incidence, and Management of Spinal Cord Monitoring Alerts in Pediatric Cervical Spine Surgery.

Perioperative spinal cord injury and postoperative neurological deficits are the major complications in spinal surgery. Monitoring of spinal cord function is of crucial importance. Somatosensory evoked potentials and transcranial electric motor-evoked potentials are now widely used in cervical spine surgery. Although much has been written on spinal cord monitoring in adult spinal surgery, very little has been published on the incidence and management of monitoring of cervical spine surgery in the pediatric population. The goal of this research was to review the recognition, incidence, and management of spinal cord monitoring in pediatric patients undergoing cervical spine surgery over the course of twenty years in a single institution. We postulate spinal cord monitoring alerts in pediatric cervical spine surgery are underreported. An IRB-approved retrospective single institution review of pediatric cervical spine cases from 1997 to 2017 was performed. Both the surgeon's dictated operative note and the neuromonitoring team's dictated note were reviewed for each case, and both were cross referenced and correlated with one another to ensure no alerts were missed. All monitoring changes were assumed to be significant and reported. The incidence of alerts, type of changes, and corrective maneuvers were noted. New postoperative neurological injuries were recorded. From 1997 to 2017 fifty-three patients underwent a total of 69 procedures involving the cervical spine. Fourteen procedures (20%) were not monitored, whereas 55 procedures were 80%. There were 12 procedures (21.8%) complicated by neuromonitoring alerts. The number of cases complicated by alerts doubles that previously reported, and it is important to note there were no new permanent neurological deficits recorded over the study period. Corrective strategies were implemented once the operating surgeon was notified of the neuromonitoring alert. Aborting the case was then considered if corrective strategies failed to restore baseline neurophysiology. Level IV.

INTRAOPERATIVE DIAGNOSIS OF NEUROLOGICAL COMPLICATIONS IN SURGERY OF SEVERE SCOLIOSIS: REPORT OF CLINICAL CASES

Clinical observations of 13- and 15-year-old patients with severe (118° and 133°) idiopathic scoliosis, subjected to operative correction with the use of segmental instrumentation are presented. Intraoperative monitoring of the spinal cord function was performed by recording motor potentials of the brain and skin thermometry from the lower limbs (authors’ technique). During the operation, there was a gradual decrease in potentials in one case and sharp in another, with no changes in cutaneous temperature. Based on the data of skin thermometry, surgeons decided not to remove the implant and to bring the operation to completion in both cases. In the postoperative period, neurological complications were not revealed. The conclusion is made about the advisability of including the skin thermometry in a complex of intraoperative monitoring of spinal cord function in patients with spine deformities.

Deep Serratus Plane Catheter for Management of Acute Postthoracotomy Pain After Descending Aortic Aneurysm Repair in a Morbidly Obese Patient: A Case Report.

Regional procedures for postthoracotomy pain control have classically focused on paravertebral blocks and thoracic epidurals; however, these techniques may be challenging in an increasingly obese population and contraindicated with numerous anticoagulant and antiplatelet agents. While less studied, truncal blocks allow analgesic intervention for this growing patient cohort. This case report describes placement of a deep serratus anterior plane catheter in an intubated, morbidly obese patient with a lumbar drain who failed extubation secondary to acute postthoracotomy pain. The serratus plane catheter facilitated extubation and adequate analgesia without prohibiting anticoagulant use or interfering with the monitoring of spinal cord function.

ID 136 – Accidental spinal cord contusions during spine deformity surgeries

Introduction Accidental spinal cord contusions are a rare event during the surgical correction of spinal deformities Methods Multicenter (5 centers), observational, retrospective study. 691 patients with spinal deformities who underwent surgical correction. Intraoperative neurophysiologic monitoring of spinal cord function was performed with motor (MEPs) and somatosensory (SSEPs) evoked potentials. Results 23 patients suffered a spinal cord contusion, which become evident by a neurophysiologic event with a constant pattern. Ipsilateral MEPs were lost in the first place. Following that, contralateral MEPs were lost, and finally, SSEPs dropped. In the 19 cases with MEPs lost and preserved SSEPs, MEPs recovered during surgery. 4 of these patients presented a transient post-operative paresis with complete recovery, and the rest were asymptomatic. In the four cases which presented complete loss of MEPs and significant changes in the SSEPs, these changes did not recover, and the four patients presented some degree of post-operative paraparesis. Three of them were completely recovered after a few months. Conclusion Intraoperative accidental spinal cord contusions which produce a selective MEPs loss with intraoperative recovery have an excellent prognosis. When the contusions also produce changes on the SSEPs, they have a worst outcome, and produce transient neurologic sequelae.

Spinal cord stimulation for cancer-related pain in adults.

This is an update of a review first published in The Cochrane Library in Issue 3, 2013. Cancer-related pain places a heavy burden on public health with related high expenditure. Severe pain is associated with a decreased quality of life in patients with cancer. A significant proportion of patients with cancer-related pain are under-treated. There is a need for more effective control of cancer-related pain. Spinal cord stimulation (SCS) may have a role in pain management. The effectiveness and safety of SCS for patients with cancer-related pain is currently unknown. This systematic review evaluated the effectiveness of SCS for cancer-related pain compared with standard care using conventional analgesic medication. We also appraised risk and potential adverse events associated with the use of SCS. This is an update of a review first published in The Cochrane Library in Issue 3, 2013. The search strategy for the update was the same as in the original review. We searched the following bibliographic databases in order to identify relevant studies: the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library; MEDLINE; EMBASE; and CBM (Chinese Biomedical Database) in October 2014. We also handsearched relevant journals. There were no language restrictions. We planned to include randomised controlled trials (RCTs) that directly compared SCS with other interventions with regards to the effectiveness of pain management. We also planned to include cross-over trials that compared SCS with another treatment. We planned to identify non-randomised controlled trials but these would only be included if no RCTs could be found. The literature search for the update of this review found 121 potentially eligible articles. The initial search strategy yielded 430 articles. By scrutinising titles and abstracts, we found 412 articles irrelevant to the analytical purpose of this systematic review due to different scopes of diseases or different methods of intervention (intrathecal infusion system; oral medication) or aims other than pain control (spinal cord function monitoring, bladder function restoration or amelioration of organ metabolism). The remaining 18 trials were reviewed as full manuscripts. No RCTs were identified. Fourteen sporadic case reports and review articles were excluded and four before-and-after case series studies (92 participants) were included. Two review authors independently selected the studies to be included in the review according to the prespecified eligibility criteria. A checklist for methodological quality of non-randomised controlled trials was used (STROBE checklist) and all review authors discussed and agreed on the inclusion of trials and the results of the quality assessment. No new studies were identified for inclusion in this update of the review. Four before-and-after case series studies (a total of 92 participants) met our criteria for inclusion in the previous version of the review. All included trials adopted a visual analogue scale (VAS) to evaluate pain relief. Heterogeneity existed in terms of baseline characteristics, electrode and stimulator parameters, level of implantation and route of implantation; each trial reported data differently. In two trials, pain relief was achieved in 76% (48/63) of participants at the end of the follow-up period. In the third trial, pre-procedure VAS was 6 to 9 (mean 7.43 ); the one-month post-implant VAS was 2 to 4 (mean 3.07); the 12-month post-implant VAS was 1 to 3 (mean 2.67). In the fourth trial, the pre-procedure VAS was 6 to 9 (mean 7.07); 1 to 4 (mean 2.67) at one-month; 1 to 4 (mean 1.87) at 12 months. Analgesic use was largely reduced. The main adverse events were infection of sites of implantation, cerebrospinal fluid (CSF) leakage, pain at the sites of electrodes, dislodgement of the electrodes, and system failure; however, the incidence in participants with cancer could not be calculated. Since all trials were small, non-randomised controlled trials, they carried high or unclear risk of all types of bias. Since the first publication of this review, no new studies were identified. Current evidence is insufficient to establish the role of SCS in treating refractory cancer-related pain. Future randomised studies should focus on the implantation of SCS in participants with cancer-related pain.

47. Monitoring of motor evoked potentials during thoracoabdominal aortic aneurysm repair

Spinal cord ischemia is one of the most serious complications of thoracoabdominal aortic aneurysm surgery. Hypotermia, cerebrospinal fluid drainage and pressure monitoring, reimplantation of segmental arteries and staged clamping are usual methods of spinal cord protection. We use electrophysiological monitoring of motor evoked potentials (MEPs) to measure a functional status of the thoracolumbar spinal cord during thoracoabdominal aortic surgery. Between May 2011 and May 2013, MEPs monitoring-assisted thoracoabdominal repair was performed in 14 patients. Stable MEPs were reproducible in 10 of 14 patients (71%). Nine of them displayed no neurological deficit after postoperative awakening. One patient suffered light hemiparesis due to brain ischemia. Bilateral MEPs loss occurred in 4 of 14 patients. Two of them recovered after spinal-cord protecting interventions with no neurological deficit. One patient died early after surgical intervention in the ICU and it was not possible to assess neurological functions in this patient. The remaining patient suffered left-sided hemiparesis, which improved to a very light deficit within several days after the procedure. There was no case with paraparesis or paraplegia in our group. Neurophysiological monitoring of spinal cord function is necessary to detect spinal cord ischemia. An advantage of MEPs comparing to the somatosensory evoked potentials (SSEPs) is rapid response to spinal malperfusion and corrective steps to prevent or reduce the extent of paraplegia and paraparesis can be taken with little delay. False positive results, detected in two patients of our group, are well known and described in literature and were not detrimental for the patients.

Evolving Compartment Syndrome Detected by Loss of Somatosensory- and Motor-evoked Potential Signals During Cervical Spine Surgery

Neurologic injury is a rare but devastating complication of spinal surgery that can result in mild sensory to severe motor deficits. Surgeons increasingly use electrophysiological spinal cord function monitoring, including somatosensory- and motor-evoked potentials, intraoperatively to provide information about spinal cord function, aid in surgical decision making, improve outcomes, and reduce complication rates. By providing real-time information about the dorsal and anterior motor column function, somatosensory- and motor-evoked potentials signals allow surgeons to reverse noticeable changes and avoid devastating neurologic injuries. Recognizing changes in baseline signals in the setting of known risk factors enables surgeons to correct these risks. This article describes a case in which somatosensory- and motor-evoked potentials monitoring were lost in the setting of an impending right forearm compartment syndrome during 2-level anterior cervical diskectomy and fusion. To the authors' knowledge, this is the first reported case of spinal cord monitoring detecting an evolving compartment syndrome during cervical spine surgery. The early changes in signal intensity enabled the surgeon to search for a cause and remedy the situation by removing the infiltrated intravenous line. Without the observed changes in somatosensory- and motor-evoked potentials, it is likely that the compartment syndrome may have progressed to the point of requiring fasciotomy to prevent lasting neuromuscular injury. This article describes a new cause of changes in electrophysiological monitoring and further displays the usefulness of somatosensory- and motor-evoked potentials monitoring during even routine spinal surgery.

Techniques of intraoperative monitoring for spinal cord function: their past, present, and future directions

Purpose: The authors discuss the use of intraoperative monitoring of spinal cord function as an essential part of operations in which the spinal cord is at risk. Although early documented cases of intraoperative monitoring were during operations to correct spinal deformities such as scoliosis, intraoperative monitoring has also increased safety during other operations, such as tumor resection and arteriovenous malformation ablation.Methods: The authors highlight details involved in monitoring spinal cord function intraoperatively and discuss historical, current, and future perspectives on the use of these monitoring techniques as an essential part of operations in which the spinal cord is at risk.Results: Intraoperative monitoring techniques mitigate the risk of post-operative deficits to the spinal cord by detecting injuries before they become permanent and while they can be reversed.Conclusions: Intraoperative spinal cord monitoring is safe, cost-effective, and valuable in reducing post-operative sensory and motor deficit. This technique should continue to be refined and its use consistently applied in any procedure where injury to the spinal cord is possible.

2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM Guidelines for the Diagnosis and Management of Patients With Thoracic Aortic Disease

2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM Guidelines for the Diagnosis and Management of Patients With Thoracic Aortic Disease

Changes of somatosensory and transcranial magnetic stimulation motor evoked potentials in experimental spinal cord injury

To study the changes of somatosensory evoked potential (SEP) and transcranial magnetic simulation motor evoked potential (TMS-MEP) in experimental spinal cord injury (SCI). Thirty-two rabbits were randomly divided into 4 equal groups. All rabbits were anesthetized for 90 min. A group (Group A) underwent only laminectomy of T12 without SCI, stimulation with different intensities was used to induce SEP and TMS-MEP to determine the most appropriate stimulation intensity. The EPs were recorded before and after the operation. The other 3 groups underwent laminectomy of T12 to expose the dura, and a spinal cord compressing apparatus weighing 40 g was put on the intact dura and dorsal surface of spinal cord underneath for 5, 15, and 30 min respectively (Groups B, C, and D). SEP and TMS-MEP were detected after anesthesia, after exposure of spinal cord, and 5 and 30 min, 1 and 6 h, and 1, 3, and 7 d. The latency and amplitude of each wave were measured. The data were analyzed by analysis of variance, t-test and linear correlation. Tarlov behavior score was used to assess the motor function before the operation and 1, 3, and 7 days after SCI. It was found that 100% intensity stimulus obtained stable and reliable MEP waves. Anesthetic did not influence the EPs. The amplitude of SEP began to decrease 5 min after SCI and the latency began to increase 30 min after SCI. And both the amplitude and latency, especially the former, of MEP began to significantly change 5 min after SCI. The latency levels of SEP and MEP increased and the amplitude decreased after compression time-dependently during a certain range of time (all P <0. 05). The latency of SEP recovered 1 d after SCI and the amplitude recovered 7 d after; and the latency of MEP recovered 3 d after SCI and the amplitude did not recover even 7 d after SCI. The Tarlov scores of all groups were all 5 before operation, and the Tarlov scores of Group C and D became 1 d after operation and then increased later, however, still lower than 5 even at day 7. SEP and TMS-MEP are very sensitive to SCI, in particular, the change of amplitude is more sensitive then the latency change and can more accurately reflect the degree of SCI. Combination of SEP and TMS-MEP objectively reflects the SCI degree. EP measurement, as a noninvasive technique, has great value in monitoring spinal cord function.

Poster 265: Somatosensory and Motor Evoked Potential Application in Maxillofacial Trauma: Monitoring of Spinal Cord Function During Mandibular Fracture Repair With Concomitant Cervical Spine Injury

Poster 265: Somatosensory and Motor Evoked Potential Application in Maxillofacial Trauma: Monitoring of Spinal Cord Function During Mandibular Fracture Repair With Concomitant Cervical Spine Injury

Assessment of Spinal Cord Circulation and Function in Endovascular Treatment of Thoracic Aortic Aneurysms

In thoracic stent graft repair, the importance of segmental artery (SA) occlusion and the role of blood pressure management during the intraoperative and directly postoperative period are not clear. To study these aspects in relation to spinal cord ischemia, our protocol in the endovascular treatment of descending thoracic aneurysms covering segmental arteries T8 and lower includes preoperative assessment of the spinal cord circulation using magnetic resonance angiography, intraoperative cerebrospinal fluid drainage, and spinal cord function monitoring using motor evoked potentials (MEPs). Thirteen patients with thoracic aortic aneurysms and dissections needing stent graft coverage of T8 and lower were included. In 9 patients, spinal cord circulation was evaluated preoperatively by magnetic resonance angiography. In 12 patients, MEPs were recorded during the endovascular procedure. A combination of both techniques was used in 8 patients. The distal stent graft landing zone covered the intercostal arteries up to T10 in 4 patients, up to T11 in 7 patients, up to T12 in 1 patient, and all SAs to the aortic bifurcation in 1 patient. In 6 patients, the SA feeding the Adamkiewicz artery was covered by the stent graft. In three patients, intersegmental collaterals were present to the SA feeding the Adamkiewicz artery. The MEPs decreased to 50% and 30% in 2 patients, recovering to levels above 50% by elevation of the mean arterial pressure. Postoperatively, no signs of paraplegia were present. We believe that the presence of intersegmental collaterals decreases the risk of spinal cord ischemia during endovascular thoracic aortic aneurysm repair. Monitoring of MEPs during endovascular thoracic procedures shows no decrease in most cases. However, if a decrease of MEPs occurs, this can be reversed by elevation of the mean arterial pressure.

Intraoperative Applications Of The H-Reflex And F-Response: A Tutorial

Traditional intraoperative monitoring of spinal cord function involves the use of three techniques: 1. Orthodromic ascending somatosensory evoked potentials (SSEPs) and 2. antIDromic descending neurogenic somatosensory evoked potentials (DNSSEPs) monitor long-tract sensory function. SSEPs and DNSSEPs do not monitor interneuronal gray matter function. 3. Transcranial motor evoked potentials (TMEPs) monitor descending long-tract motor function and measure interneuronal gray matter function by activating motor neurons. TMEPs activate from 4-5% of the motor neuron pool. When using TMEPs 95-96% of the motor spinal cord systems activating the motor neurons are not monitored. Our ability to interact with our environment involves not only intact sensation and strength, but also complex coordinated motor behavior. Complex coordinated motor behavior is controlled by groups of electrically-coupled spinal cord central pattern generators (CPGs). The components of CPGs are: descending and propriospinal systems, peripheral input, and segmental interneurons. The point-of-control is the level of excitation of interneurons, which is determined by the integrated activity of the other components. Spinal cord injury (SCI) changes segmental reflex gain by uncoupling these components. Changes in gain are detected by recordings from muscles. SSEPs, DNSSEPs and TMEPs provIDe limited information about the status of CPGs. H-reflexes measure the function of from 20-100% of the motor neuron pool. F-responses measure the function of from 1-5% of the motor neuron pool. H-reflexes and F-responses provIDe information about the degree of coupling between CPG components. Recording H-reflexes and F-responses together with SSEPs and TMEPs not only monitors spinal cord long-tract function, but also provIDes a multiple-systems approach that monitors those spinal cord systems that are responsible for the control of complex coordinated motor behavior. The objective of this paper is to describe how H-reflexes and F-responses can be used to monitor complex coordinated motor behavior.

Neurophysiological monitoring of spinal cord function during instrumented anterior cervical fusion

Background context Somatosensory evoked potentials (SSEPs) monitor global spinal cord function, and the interpretation of motor loss is based on inferred rather than direct measurements. Therefore, SSEPs may not be useful for identifying motor function deficits caused by anterior spinal column injury or nerve root injury during decompression or placement of instrumentation. For these reasons, adjunctive methods for monitoring may be especially useful during cervical spine surgery. Purpose To evaluate the effectiveness of SSEP and transcranial electrical motor evoked potential (tceMEP) monitoring of spinal cord function during anterior fusion of the cervical spine. Study design/setting Retrospective review. Patient sample Consecutive instrumented, anterior cervical spine surgeries performed by the same surgeon at a single institution for 119 patients. Outcome measures Record of neurophysiological alerts during surgery and record of postoperative neurological deficits not present before surgery. Methods Spinal cord function was monitored intraoperatively with recordings of ulnar and posterior tibial nerve SSEPs and tceMEPs. Results Six neurophysiologic alerts occurred that prompted surgeon and/or anesthesiologist intervention. Three patients developed new motor weakness after surgery. One patient had temporary right-leg weakness that was predicted accurately by the disappearance of the right lower extremity tceMEPs. One patient had additional temporary postoperative compromise of the right C5–C6 spinal nerve roots that could not be detected intraoperatively because of absent baseline tceMEPs from the affected muscles. For one patient who developed quadriparesis postoperatively, tceMEP monitoring was precluded by the excessive use of neuromuscular blockade during the procedure. Conclusions The results illustrate the potential utility of intraoperative SSEPs and the tceMEPs for detection of changes in spinal cord function related to patient positioning and hemodynamic effects during anterior cervical fusion.

Kathleen Mears Lecture: Intraoperative Neurophysiologieal Monitoring—A Contemporary Perspective

ABSTRACT.Intraoperative neurophysiologieal monitoring (IONM) has gained widespread acceptance over the past five years, due in part to the myriad publications demonstrating the reliability, validity, and clinical efficacy of this burgeoning specialty. In fact, monitoring of spinal cord function is now considered standard of care during surgical correction of scoliosis. Likewise, cranial nerve monitoring now enjoys similar universal acceptance during posterior fossa tumor surgery. Recent technological advances in spinal instrumentation systems, for both deformity correction and internal fixation, have broadened the scope of patients who can now benefit from complex spine surgery, far beyond scoliosis. Similarly, advances in neurosurgery have also given rise to broadened opportunity for neuromonitoring techniques and strategies to keep pace with advances in a multitude of surgical specialties. The increase in demand for spinal cord monitoring reflects the increase in the intricacy of corrective spine procedures and the subsequent risk of iatrogenic injury to the spinal cord, nerve roots, or both. The monitoring demands for these procedures extend far beyond the time-honored somatosensory evoked potential (SSEP) and the brainstem auditory evoked potential (BAEP). Newer techniques that assess central nervous system (CNS) function more directly, such as transcranial motor evoked potentials, nerve root mapping, motor and speech cortex mapping, transcranial microdoppler flow studies, and cerebral oximetry, are now included in the neuromonitoring armamentarium either to augment or replace historical indirect measures such as SSEPs and EEG. As the field of IONM approaches its third decade, we are forced to examine current and future perspectives relating to the broad-based knowledge demands required in neurophysiology, surgical anatomy, anesthesia, and the like that now far exceed that needed previously. The chalenge is indeed formidable.

Prevention of spinal cord ischaemia during descending thoracic and thoracoabdominal aortic surgery.

Surgery of the descending and thoracoabdominal aorta has been associated with post-operative paraparesis or paraplegia. Different strategies, which can be operative or non-operative, have been developed to minimise the incidence of neurological complications after aortic surgery. This review serves to summarise the current practice of spinal cord protection during surgery of the descending thoracoabdominal aortic surgery. The pathophysiology of spinal cord ischaemia will also be explained. The incidence of spinal cord ischaemia and subsequent neurological complications was associated with (1) the duration and severity of ischaemia, (2) failure to establish spinal cord supply and (3) reperfusion injury. The blood supply of the spinal cord has been extensively studied and the significance of the artery of Adamkiewicz (ASA) being recognised. This helps us to understand the pathophysiology of spinal cord ischaemia during descending and thoracoabdominal aortic operation. Techniques of monitoring of spinal cord function using evoked potential have been developed. Preoperative identification of ASA facilitates the identification of critical intercostal vessels for reimplantation, resulting in re-establishment of spinal cord blood flow. Different surgical techniques have been developed to reduce the duration of ischaemia and this includes the latest transluminal techniques. Severity of ischaemia can be minimised by the use of CSF drainage, hypothermia, partial bypass and the use of adjunctive pharmacological therapy. Reperfusion injury can be reduced with the use of anti-oxidant therapy. The aetiology of neurological complications after descending and thoracoabdominal aortic surgery has been well described and attempts have been made to minimise this incidence based on our knowledge of the pathophysiology of spinal cord ischaemia. However, our understanding of the development and prevention of these complications require further investigation in the clinical setting before surgery on descending and thoracoabdominal aorta to be performed with negligible occurrence of these disabling neurological problems.