Multimodal Intraoperative Monitoring Research Articles

Early Detection of Brachial Plexus Injury in Prone Position Surgery Using Multimodal Intraoperative Monitoring: A Cross-sectional Study

Early Detection of Brachial Plexus Injury in Prone Position Surgery Using Multimodal Intraoperative Monitoring: A Cross-sectional Study

Influence of different intraoperative fluid management on postoperative outcome after abdominal tumours resection.

Intraoperative fluid management is a crucial aspect of cancer surgery, including colorectal surgery and pancreatoduodenectomy. The study tests if intraoperative multimodal monitoring reduces postoperative morbidity and duration of hospitalisation in patients undergoing major abdominal surgery treated by the same anaesthetic protocols with epidural analgesia. A prospective study was conducted in 2 parallel groups. High-risk surgical patients undergoing major abdominal surgery were randomly selected in the control group (CG), where standard monitoring was applied (44 patients), and the protocol group (PG), where cerebral oxygenation and extended hemodynamic monitoring were used with the protocol for intraoperative interventions (44 patients). There were no differences in the median length of hospital stay, CG 9 days (interquartile range [IQR] 8 days), PG 9 (5.5), p = 0.851. There was no difference in postoperative renal of cardiac impairment. Procalcitonin was significantly higher (highest postoperative value in the first 3 days) in CG, 0.75 mcg/L (IQR 3.19 mcg/L), than in PG, 0.3 mcg/L (0.88 mcg/L), p = 0.001. PG patients received a larger volume of intraoperative fluid; median intraoperative fluid balance +1300 ml (IQR 1063 ml) than CG; +375 ml (IQR 438 ml), p < 0.001. There were significant differences in intraoperative fluid management and vasopressor use. The median postoperative value of procalcitonin was significantly higher in CG, suggesting differences in immune response to tissue trauma in different intraoperative fluid status, but there was no difference in postoperative morbidity or hospital stay.

Intraoperative neuromonitoring predicts postoperative deficits in severe pediatric spinal deformity patients.

To evaluate intraoperative monitoring (IOM) alerts and neurologic deficits during severe pediatric spinal deformity surgery. Patients with a minimum Cobb angle of 100° in any plane or a scheduled vertebral column resection (VCR) with minimum 2-year follow-up were prospectively evaluated (n = 243). Preoperative, immediate postoperative, and 2-year postoperative neurologic status were reported. Radiographic data included preoperative and 2-year postoperative coronal and sagittal Cobb angles and deformity angular ratios (DAR). IOM alert type and triggering event were recorded. SRS-22r scores were collected preoperatively and 2-years postoperatively. IOM alerts occurred in 37% of procedures with three-column osteotomy (n = 36) and correction maneuver (n = 32) as most common triggering events. Patients with IOM alerts had greater maximum kyphosis (101.4° vs. 87.5°) and sagittal DAR (16.8 vs. 12.7) (p < 0.01). Multivariate regression demonstrated that sagittal DAR independently predicted IOM alerts (OR 1.05, 95% CI 1.02-1.08) with moderate sensitivity (60.2%) and specificity (64.8%) using a threshold value of 14.3 (p < 0.01). IOM alerts occurred more frequently in procedures with new postoperative neurologic deficits (17/24), and alerts with both SSEP and TCeMEP signals were associated with new postoperative deficits (p < 0.01). Most patients with new deficits experienced resolution at 2 years (16/20) and had equivalent postoperative SRS-22r scores. However, patients with persistent deficits had worse SRS-22r total score (3.8 vs. 4.2), self-image subscore (3.5 vs. 4.1), and function subscore (3.8 vs. 4.3) (p ≤ 0.04). Multimodal IOM alerts are associated with sagittal kyphosis, and predict postoperative neurologic deficits. Most patients with new deficits experience resolution of their symptoms and have equivalent 2-year outcomes. II.

Multimodal Intraoperative Monitoring During Supratentorial Aneurysm Surgery. A Comparative Study

Multimodal Intraoperative Monitoring During Supratentorial Aneurysm Surgery. A Comparative Study

Need for head and neck repositioning to restore electrophysiological signal changes at positioning for cervical myelopathy surgery

ObjectiveTo evaluate the incidence of significant intraoperative electrophysiological signal changes during surgical positioning, and to assess the effectiveness of head and neck repositioning on the restoration of signals, among patients undergoing surgery for cervical myelopathy. Material and methodsWe used multimodal intraoperative monitoring (somatosensory [SEP] and motor evoked potentials [MEP] and spontaneous electromyography) before and after patients’ positioning in a consecutive cohort of 103 patients operated for symptomatic cervical myelopathy. Significant changes were defined as>50% attenuation in amplitude or>10% increase in latency of SEP, or abolishment or 50–80% attenuation of MEP. ResultsOut of 103 patients (34.9% female, median age 54.5 years) 88 underwent laminectomy (85.4%) and 15 (14.6%) anterior approach. At the time of positioning, signal alterations occurred in 44 patients (42.7%), yet only 11 patients (10.7%) showed alarming changes. Immediate neck repositioning of these resulted in complete (n=6) or partial (n=4) restoration of potentials, yielding no postoperative deficits. The patient in which signals could not be restored after repositioning resulted in added postoperative deficit. The accuracy (true positives plus true negatives) of monitoring to detect new neurological deficits was 99.0% (102/103) for the entire cohort, and 100% (11/11) for those showing significant changes at the moment of positioning. Overall, only 1 patient, with non-significant SEP attenuation, experienced a new postoperative deficit, yielding a 0.97% rate of false negatives. ConclusionAmong patients undergoing surgery for cervical myelopathy, 10.7% showed alarming electrophysiological signal changes at the time of positioning. Immediate repositioning of the neck resulted in near always restoration of potentials and avoidance of added neurological damage. Complete or partial restoration of potentials after repositioning yielded no postoperative deficits.

Value of Evoked Potential Changes Associated with Neck Extension Prior to Cervical Spine Surgery.

Multimodal intraoperative monitoring (MIOM) is a useful tool to warn surgeons to intervene for intraoperative spinal cord injury in cervical spine surgery. However, the value of MIOM remains controversial before cervical spine surgery. To explore the value of MIOM in early detecting spinal cord injury associated with neck extension before cervical spine surgery. Data of 191 patients receiving cervical spine surgery with the MIOM were enrolled from June 2014 to June 2020. The subjects were divided into a group of evoked potentials (EP) changes and a group of no EP changes for analysis according to the monitoring alerts or not. Five (2.62%) patients showed EP changes associated with neck extension during intubation or positioning. After early different interventions, such as repositioning and timely surgical decompression, none or transient postoperative neurological deficits were observed in four cases, and only one case was with permanent neurological deficits. The average preoperative Japanese Orthopaedic Association (JOA) scores of the group with EP changes were lower than those of the group with no EP changes (P = 0.037 < 0.05). There was no statistical significance in gender, average age, mean Pavlov ratio, and the minimum Palov ratio between the two groups (P > 0.05). The MIOM could identify spinal cord injury associated with neck extension before cervical spine surgery. Active and effective interventions could prevent or reduce permanent postoperative neurological deficits. Severe spinal cord compression might be a risk factor for EP changes.

Disrupting self-evaluative processing with electrostimulation mapping during awake brain surgery

Brain awake surgery with cognitive monitoring for tumor removal has become a standard of treatment for functional purpose. Yet, little attention has been given to patients’ interpretation and awareness of their own responses to selected cognitive tasks during direct electrostimulation (DES). We aim to report disruptions of self-evaluative processing evoked by DES during awake surgery. We further investigate cortico-subcortical structures involved in self-assessment process and report the use of an intraoperative self-assessment tool, the self-confidence index (SCI). Seventy-two patients who had undergone awake brain tumor resections were selected. Inclusion criteria were the occurrence of a DES-induced disruption of an ongoing task followed by patient’s failure to remember or criticize these impairments, or a dissociation between patient’s responses to an ongoing task and patient’s SCI. Disruptions of self-evaluation were frequently associated with semantic disorders and critical sites were mostly found along the left/right ventral semantic streams. Disconnectome analyses generated from a tractography-based atlas confirmed the high probability of the inferior fronto-occipital fasciculus to be transitory ‘disconnected’. These findings suggest that white matters pathways belonging to the ventral semantic stream may be critically involved in human self-evaluative processing. Finally, the authors discuss the implementation of the SCI task during multimodal intraoperative monitoring.

Surgical Management of Symptomatic Lumbar, Sacral, and Lumbosacral Plexus Tumors: a Peripheral Nerve Unit Experience.

Data concerning the surgical treatment of lumbosacral plexus tumors (LSPTs) is scarce. This study aims to present our experience with a series of 19 patients surgically treated for symptomatic LSPTs at our institution. This is a retrospective study of 19 patients surgically treated for symptomatic LSPTs from 2011 to 2019. Clinical data were retrieved from medical records and consisted of age, gender, clinical presentation, location of the lesion, surgical approach, final histopathologic diagnosis, follow-up time, outcomes, and complications. Nineteen surgical procedures were conducted. Thirteen patients were female and six, male. The median age of patients was 45 years (range 20 to 63 years). No patients harbored genetic syndromes. Surgical treatment appears to be correlated to the reduction of pain in patients with peripheral nerve sheath tumors (PNSTs), as assessed by visual analog scale (VAS). Sixteen patients did not present with new-onset deficits during follow-up (84.2%), two of whom recovered from their preoperative deficit. Four patients presented with postoperative weakness. The histopathological diagnoses were 11 schwannomas, four neurofibromas, three metastases, and one lymphoma. LSPTs are rare. When surgical treatment is indicated, it usually requires multidisciplinary management. Surgery appears to be effective concerning the reduction of pain in PNSTs and may also recover neurological deficits. Iatrogenic neurological deficits are an evident risk, such that intraoperative multimodal monitoring should always be performed if available. In lesions involving the sacral plexus, we found it to be indispensable.

Evaluation of immediate complications and 10-years neurological outcomes in patients after reconstructive interventions on the ascending aorta and the aortic arch

OBJECTIVE To estimate the frequency of early postoperative neurological complications in patients undergoing planned surgery on the ascending aortic and arch of the aorta, and their long-term outcomes. MATERIAL AND METHODS The prospective study included 100 patients who were operated on at the FSBSI Petrovsky Russian Research Center of Surgery. In group I (n=50), operations were performed on the aortic arch with hypothermic circulatory arrest (26 °C) and antegrade cerebral perfusion. Patients in group II underwent prosthetics of the ascending aorta with extracorporeal circulation and moderate hypothermia (32 °C). All patients underwent monitoring of cerebral and tissue oxygenation, transcranial Doppler and testing of cognitive functions before and after surgery, and after 5 and 10 years of follow-up. RESULTS Postoperative stroke in group I was observed in 1 (2%) patient, no cases were observed in group II. Delirium was detected in 14% of patients in group I and 6% of patients in group II, its subsyndromal form was found in 6 and 4%, respectively. Moderate cognitive impairment in the immediate postoperative period was found in 42 and 26%; severe in 8% of group I. After 5 years of follow-up, the number of patients with moderate and severe cognitive impairment was 23.1 and 12.8%, respectively. After 10 years, severe disorders were identified in 37.5 and 21.9% of patients. CONCLUSION In cardiac surgery patients, intraoperative multimodal monitoring allows dynamic regulation of antegrade cerebral perfusion. Dynamic testing of cognitive functions and early detection of delirium in the immediate postoperative period improve long-term neurological treatment outcomes.

Multimodal Intraoperative Neural Monitoring for Neurosurgical Spinal Operations Standard of Care–A Debate or a Foregone Conclusion and the Future Ahead

Multimodal Intraoperative Neural Monitoring for Neurosurgical Spinal Operations Standard of Care–A Debate or a Foregone Conclusion and the Future Ahead

The Role of Neurophysiological Monitoring during Complex Aneurysm Surgery: Report of Two Cases and Review of the Literature

AbstractThe surgical treatment of intracranial aneurysms is a routine operation in the neurosurgeon practice. Complex aneurysms are those with morphological irregularities, usually large or giant; thrombosed, partially thrombosed or calcified; with aberrant fundus/neck ratio and near eloquent neurological structures. These cases demand special skills by the surgical team. The present article is a report of two cases of complex aneurysms successfully treated, with a discussion on the role of neurophysiological monitoring. In these two cases of supra- and infratentorial complex giant aneurysms, intraoperative monitoring was extremely relevant. Thus, we believe that treating complex and giant aneurysms carries several pitfalls, and the use of multimodal intraoperative monitoring is mandatory to mitigate risks and deliver the best result to the patient.

The efficacy of intraoperative multimodal monitoring in pedicle subtraction osteotomies of the lumbar spine.

Iatrogenic spine injury remains one of the most dreaded complications of pedicle subtraction osteotomies (PSOs) and spine deformity surgeries. Thus, intraoperative multimodal monitoring (IOM), which has the potential to provide real-time feedback on spinal cord signal transmission, has become the gold standard in such operations. However, while the benefits of IOM are well established in PSOs of the thoracic spine and scoliosis surgery, its utility in PSOs of the lumbar spine has not been robustly documented. The authors' aim was to determine the impact of IOM on outcomes in patients undergoing PSO of the lumbar spine. All patients older than 18 years who underwent lumbar PSOs at the authors' institution from 2007 to 2017 were analyzed via retrospective chart review and categorized into one of two groups: those who had IOM guidance and those who did not. Perioperative complications were designated as the primary outcome measure and postoperative quality of life (QOL) scores, specifically the Parkinson's Disease Questionnaire-39 (PDQ-39) and Patient Health Questionnaire-9 (PHQ-9), were designated as secondary outcome measures. Data on patient demographics, surgical and monitoring parameters, and outcomes were gathered, and statistical analysis was performed to compare the development of perioperative complications and QOL scores between the two cohorts. In addition, the proportion of patients who reached minimal clinically important difference (MCID), defined as an increase of 4.72 points in the PDQ-39 score or a decrease of 5 points in the PHQ-9 score, in the two cohorts was also determined. A total of 95 patients were included in the final analysis. IOM was not found to significantly impact the development of new postoperative deficits (p = 0.107). However, the presence of preoperative neurological comorbidities was found to significantly correlate with postoperative neurological complications (p = 0.009). Univariate analysis showed that age was positively correlated with MCID achievement 3 months after surgery (p = 0.018), but this significance disappeared at the 12-month postoperative time point (p = 0.858). IOM was not found to significantly impact MCID achievement at either the 3- or 12-month postoperative period as measured by PDQ-39 (p = 0.398 and p = 0.156, respectively). Similarly, IOM was not found to significantly impact MCID achievement at either the 3- or 12-month postoperative period, as measured by PHQ-9 (p = 0.230 and p = 0.542, respectively). Multivariate analysis showed that female sex was significantly correlated with MCID achievement (p = 0.024), but this significance disappeared at the 12-month postoperative time point (p = 0.064). IOM was not found to independently correlate with MCID achievement in PDQ-39 scores at either the 3- or 12-month postoperative time points (p = 0.220 and p = 0.097, respectively). In this particular cohort, IOM did not lead to statistically significant improvement in outcomes in patients undergoing PSOs of the lumbar spine (p = 0.220). The existing clinical equipoise, however, indicates that future studies in this arena are necessary to achieve systematic guidelines on IOM usage in PSOs of the lumbar spine.

Multimodal Intraoperative Spinal Cord Monitoring during Spinal Deformity Surgery: Efficacy, Diagnostic Characteristics, and Algorithm Development

Objective: This study aims to present the diagnostic characteristics of multimodal intraoperative monitoring (IOM) in spinal deformity surgery and to define and categorise the neuromonitoring events, as well as propose an algorithm of action. Materials and Methods: We reviewed 1,155 consecutive patients (807 female, 348 male) who underwent deformity correction using standardised perioperative care, cortical/cervical somatosensory evoked potentials (SSEPs), and upper/lower limb transcranial electrical motor evoked potential (MEPs) by a single surgeon. The mean age at surgery was 13.8 years (range 10–23.3). We categorised IOM events as true, transient true, and false positive or negative. Diagnostic performance criteria were calculated. Results: The most common diagnosis was adolescent idiopathic scoliosis in 717 (62%) patients. We identified 3 true positive monitoring events occurring in 2 patients (0.17%), 8 transient true positive (0.69%), and 8 transient false positive events (0.69%). There were no false negative events and no patient had postoperative neurological complications. The multimodal IOM technique had a sensitivity of 100%, specificity of 99.3%, positive predictive value of 55.6%, and negative predictive value of 100%. Sensitivity was 100% for MEPs and multimodal monitoring compared to 20% for cortical or cervical SSEPs. The frequency of true or transient true positive events was higher (p = 0.07) in Scheuermann’s kyphosis (3/91 patients, 3.3%) compared to adolescent idiopathic scoliosis (6/717 patients, 0.84%). Conclusion: Multimodal IOM is highly sensitive and specific for spinal cord injury. This technique is reliable for the assessment of the condition of the spinal cord during major deformity surgery. We propose an algorithm of intraoperative action to allow close cooperation between the surgical, anaesthetic, and neurophysiology teams and to prevent neurological deficits.

P19-F Variability of Intraoperation monitoring parameters in patients with degenerative cervical myelopathy

Background motor cortex transcranial electric stimulation in Intraoperative monitoring (IOM) is used to assess the corticospinal functional state by measuring the fast axons conduction (registration of D-wave), motor evoked potentials (MEPs) threshold and amplitude. While D-wave is considered to be a stable parameter independent of anesthesia, the informativeness of MEPs amplitude is controversial due to its instability, especially when in cervical spine surgery. Material and methods 20 patients with cervical degenerative myelopathy underwent surgical decompression with anterior cervical discectomy. In Group 1 (10 patients) the TIVA anaestiological protocol was used and in Group 2 (10 patients) the Sevoflurane 0.6–0.8 MAC was added. In all patients before intubation MEPs threshold for m. abd. pollicis brevis, m.add. digiti minimi, m. tibialis anterior, m. add. hallucis were assessed in response to a train of 5 pulses with a duration of 0.5 ms and inter-pulse interval 2 ms. Results In the course of operation MEPs threshold increase and amplitude decrease were detected in all patients Group2. In 6 patients of Group 1 (4 – unilaterally, 2 – bilaterally) and 4 patients of Group 2 (2– unilaterally, 2 – bilaterally) during surgery MEPs responses were lost; though there were observed no signs of additional neurological deficit after surgery. Unilateral MEP changes in patients operated on cervical spine can be attributed to compression of the plexus related to the position and patient fixation; bilateral – because of traction manipulations and spinal cord ischemia. Conclusions for detection of intraoperational ischemia Multimodal IOM will be preferred.

Intraoperative Multimodal Monitoring in Pedicle Subtraction Osteotomies of the Lumbar Spine: A Narrative Literature Review.

The use of intraoperative multimodal monitoring (IOM) in spinal deformity surgeries is well documented. In particular, pedicle subtraction osteotomy (PSO), a corrective procedure for sagittal deformity of the spine, often involves IOM usage. By providing immediate feedback to the operating surgeon, IOM has the potential to eliminate or at least minimize the risk of iatrogenic neurological injury. However, despite the widespread usage of IOM, there is currently no standardization of IOM usage in complex spine surgeries, including lumbar PSOs, and decisions concerning IOM utilization are often driven by surgeon experience and preference. This creates a state of clinical equipoise, which is further complicated by the varying degrees of benefit that IOM has on patient outcomes depending on the operation and spinal levels involved. For instance, while IOM use in thoracic PSOs has been shown to be effective, there is no established consensus on the net impact of IOM use in PSOs of the lumbar spine. Although IOM has the potential to mitigate neurological damage, it also increases operation time and cost; thus, it should only be used in operations where it will have a net positive impact on patient outcomes. The question thus becomes whether PSO of the lumbar spine is one such operation. To address this, we examine the most frequently used IOM modalities and evaluate their current usage and efficacy in lumbar PSOs. Furthermore, we will also examine the utility of IOM for other surgeries of the lumbar spine, including corrective procedures for idiopathic scoliosis and degenerative scoliosis, and routine lumbar procedures, such as discectomies and decompression surgeries for foraminal and canal stenosis.

Analysis of Multimodal Intraoperative Monitoring During Intramedullary Spinal Ependymoma Surgery

To evaluate the validity of intraoperative somatosensory-evoked potential (SSEP) and motor-evoked potential (MEP) monitoring according to 2 different warning criteria during 6 months from intramedullary spinal ependymoma surgery. Twenty-six patients who underwent intramedullary spinal ependymoma surgery with intraoperative monitoring from January 2010 to June 2017 were retrospectively analyzed. We examined the sensitivity, specificity, positive predictable value, negative predictable value, and diagnostic odds ratio of SSEP and MEP monitoring for each extremity according to 2 warning criteria: 50% decline and all-or-none. The postoperative motor deficit was evaluated using the Medical Research Council scale. The postoperative neurologic deficit was followed up during 6 months. Eighty-six extremities were evaluated. The success rates of SSEP and MEP monitoring were 84.9% and 83.7%, respectively. Indeterminate cases were 1 in SSEP and 6 in MEP. All-or-none criterion in SSEP and MEP monitoring showed greater specificity, positive predictable value, and diagnostic odds ratio than 50% decline criterion during 6 months. The validity of SSEP was high in the upper extremity, whereas that of MEP was high in the lower extremity. During the follow-up, 37 of 38 extremities (97.4%) and 18 of 29 extremities (62.1%) showed improvement in sensory and motor deficit, respectively. Seven indeterminate cases also showed good clinical outcomes. Many false-positive and false-negative results of SSEP and MEP monitoring occurred during the immediate postoperative period. All-or-none criterion was more beneficial for assessing postoperative neurologic status than 50% decline criterion. This trend was maintained until 6 months after surgery.

Significance of Multimodal Intraoperative Monitoring During Surgery in Patients with Craniovertebral Junction Pathology

Although many studies have investigated the benefits of multimodal intraoperative monitoring (MIOM) during cervical spine surgery, the benefits of MIOM in craniovertebral junction (CVJ) surgery remain unclear. The objectives of the present study were to report our clinical experience in CVJ surgery with the use of MIOM and to identify risk factors that could affect MIOM changes during surgery of CVJ pathology. We reviewed the MIOM records of 146 patients who had undergone high cervical spinal surgery. The patients were grouped by the MIOM data recorded during surgery; the patients were included in either the MIOM or non-MIOM change group. The analyzed risk factors included demographic, myelopathy, preoperative Japanese Orthopedic Association (JOA) score, spinal cord diameter, and surgical factors. Univariate and multivariate analyses were performed to identify the risk factors for changes in MIOM data during surgery and postoperative neurological deficits. Our results revealed that the incidence of postoperative neurological complications was 4.1% after CVJ surgery; this rate was significantly greater in the MIOM change group than in the non-MIOM change group (21.7% vs. 0.8%; P < 0.01). Multiple regression analysis revealed that preoperative myelopathy, preoperative JOA score, and congenital anomaly/tumor were independently associated with MIOM changes during surgery. Postoperative neurological complications are not uncommon after CVJ surgery, and the incidence was significantly greater in the MIOM change group. Preoperative myelopathy, preoperative JOA score, and CVJ pathology related to congenital anomaly or tumor were independent risk factors for changes in MIOM data during surgery.

The effect of positive changes during intraoperative monitoring of the functional improvement in patients with cervical compressive myelopathy

BackgroundCervical compressive myelopathy (CCM) is a progressive, degenerative spine disease and the most common cause of spinal cord dysfunction in older individuals. Current clinical guidelines for spinal surgery recommend multimodal intraoperative monitoring (IOM) during spinal surgery as a reliable and valid diagnostic adjunct to assess spinal cord integrity. The aim of this study was to evaluate the effect of positive changes during IOM on the functional status in patients with CCM.MethodsPatients who underwent spinal surgery with IOM due to CCM were enrolled. During the surgery, patients underwent IOM using motor evoked potential (MEP) and somatosensory evoked potential (SEP). MEP and SEP were checked before and immediately after decompression. A decrease in latency >10% or an increase in amplitude >50% was regarded as a “positive changes”. Subjects were divided according to the presence of positive changes. Motor scores of American Spinal Injury Association (ASIA) impairment scale and Korean version of Modified Barthel Index (K-MBI) were evaluated before and after operation.ResultsTwenty-nine patients underwent spinal surgery due to CCM. Eleven patients showed positive changes in MEP during IOM. When the two groups were compared, improvement rate in the ASIA motor score and K-MBI were significantly higher in patients with positive changes than in patients without positive changes at 1 month after surgery. However, 6 months after surgery, there were no significance differences between the groups. Regardless of positive change, nearly all patients suffered from neuropathic pain after operation.ConclusionPositive changes in MEP during IOM may affect functional improvement 1 month after operation and early discharge without significant complications in CCM patients. However, they do not affect the neuropathic pain and long-term functional outcome. Thus, tailored proper management is needed to achieve maximal functional recovery in each patient after cervical spinal decompression surgery.

The effect of positive changes during intraoperative monitoring on the functional improvement in patients with cervical compressive myelopathy

Cervical compressive myelopathy (CCM) is a progressive, degenerative spine disease and the most common cause of spinal cord dysfunction in older individuals. Current clinical guidelines for spinal surgery strongly recommend multimodal intraoperative monitoring (IOM) during spinal surgery as a reliable and valid diagnostic adjunct to assess spinal cord integrity. The aim of this study was to evaluate the effect of positive changes during IOM on the functional status in patients with CCM. Patients who underwent spinal surgery with IOM due to CCM were enrolled. During the surgery, patients underwent IOM using motor evoked potential (MEP) and somatosensory evoked potential (SEP). MEP and SEP were checked before and immediately after decompression. A shortened in latency greater than 10% or an increase in amplitude greater than 50% was regarded as a ‘positive changes’. Subjects were divided according to the presence of positive changes. Motor scores of American Spinal Injury Association (ASIA) impairment scale and Korean version of modified Barthel index (K-MBI) were evaluated before and after operation. Twenty-nine patients underwent spinal surgery due to CCM. Among these patients, 11 showed positive changes in MEP during IOM. When the two groups were compared, improvement rate in the AISA motor score and K-MBI were significantly higher in patients with positive changes than in patients without positive changes at 1 month after surgery. The duration of hospital stay was significantly shortened in the ‘positive change’ group. Regardless of positive change, nearly all patients suffered from neuropathic pain after operation. Positive changes in MEP during IOM may affect better functional improvement 1 month after operation and early discharge without significant complications in CCM patients. However they do not affect the neuropathic pain. Thus, tailored, proper management is needed to achieve maximal functional recovery in each patient after cervical spinal decompression surgery.

S115. Multimodal intraoperative neurophysiology monitoring during the resection of a 4th ventricular mass in a 2 year-old boy with hemifacial spasm and seizure

Hemifacial spasm is a disorder of the seventh cranial nerve characterised by irregular, involuntary, clonic or tonic spasms of the facial muscles. In adults it is typically a primary disorder, predominantly affecting females in the fourth and fifth decades. Neonatal onset is much rarer, in and in most instances associated with a posterior fossa mass. We report the case of a 2 year-old boy who, soon after a normal and term delivery, developed unilateral hemifacial twitching. An associated ipsilateral mass in the floor of the fourth ventricle was subsequently seen on magnetic resonance imaging of the brain. A craniotomy was performed for resection of the visualised mass. A complex post anaesthetic Neurophysiology set up for intraoperative neurophysiology monitoring (IONM) and mapping was required. Brainstem auditory evoked potentials (BAEP), trans-cranial electrical motor evoked potentials (tceMEP) from face and upper limb, somatosensory evoked potentials (SEP) from the upper limbs, cranial nerve mapping and electrocorticography (ECOG) were all performed. Subdermal needle electrodes were used to record from orbicularis oris, oculi, masseter, lateral rectus and abductor pollicus brevis muscles bilaterally for tcMEPs and cranial nerve monitoring. A monopolar stimulator with needle reference was used to stimulate the cranial nerves. Buds placed in the auditory canals were used for BAEP stimulation and held in with bone wax. After opening and exposure, an 8-contact depth electrode was placed into the lesion to record resting ECOG in a referential montage, checking for interictal epileptiform activity. SEPs were obtained from stimulation of the ulnar nerves in both upper limbs and recording from corkscrew electrodes on the scalp. Cranial nerve mapping allowed the surgical team to avoid damaging the intact structures. ECOG provided real-time interictal data directly from the lesion, with no intralesional epileptiform abnormalities recorded. At closure there were no significant changes from baseline SEPs and tceMEPs. The lesion was fully resected, and the patient had a post-operative neurological exam with no deficits noted as predicted by closing neurophysiology data. To date, the patient has had no further episodes. IONM played a pivotal role during this procedure for the surgical team to tailor their surgical approach safely with maximal resection.