Wake-up Test Research Articles

Intra-operative neuromonitoring in paediatric spinal deformity surgery: a retrospective single-centre experience.

Intra-operative neuromonitoring including somatosensory evoked potentials, motor evoked potentials, and electromyography, have replaced the Stagnara wake-up test to allow early detection of neurological change during paediatric spinal deformity surgery. It is important for surgeons to recognize alerts triggered by loss of these potentials and act accordingly to prevent iatrogenic neurological damage intra-operatively. This study was conducted to determine the sensitivity and specificity of neuromonitoring alerts in paediatric spinal deformity correction surgery. A retrospective single-centre study of all patients undergoing spinal deformity surgery at a tertiary paediatric centre between 1 January 2017 and 31 December 2020 (inclusive) was conducted. Neuromonitoring alerts were identified through neurophysiology documentation, and these were correlated with neurological deficits documented in the patient record post-operatively. A total of 399 operations were included in the study, with 147 (35.7%) of these having a motor, or motor and sensory alert triggered. Fifteen (10.2% of alerts) of these patients had a post-operative neurological deficit, compared to seven (2.8% of no alerts) of those that had no neuromonitoring alert. The sensitivity for post-operative neurological deficits not resolving within 3 days was 100%, and the specificity was 65.5%. Intra-operative neuromonitoring is highly sensitive to post-operative neurological deficits lasting longer than 3 days. However, there is still scope for optimization of specificity, with many false positives identified.

Does an improvement in cord-level intraoperative neuromonitoring data lead to a reduced risk for postoperative neurologic deficit in spine deformity surgery?

To determine if an improvement in cord-level intraoperative neuromonitoring (IONM) data following data loss results in a reduced risk for new postoperative motor deficit in pediatric and adult spinal deformity surgery. A consecutive series of 1106 patients underwent spine surgery from 2015 to 2023 by a single surgeon. Cord alerts were defined by Somatosensory-Evoked Potentials (SSEP; warning criteria: 10% increase in latency or > 50% loss in amplitude) and Motor-Evoked Potentials (MEP; warning criteria: 75% loss in amplitude without return to acceptable limits after stimulation up 100V above baseline level). Timing of IONM loss and recovery, interventions, and baseline/postoperative day 1 (POD1) lower extremity motor scores were analyzed. IONM Cord loss was noted in 4.8% (53/11,06) of patients and 34% (18/53) with cord alerts had a POD1 deficit compared to preoperative motor exam. MEP and SSEP loss attributed to 98.1% (52/53) and 39.6% (21/53) of cord alerts, respectively. Abnormal descending neurogenic-evoked potential (DNEP) was seen in 85.7% (12/14) and detected 91.7% (11/12) with POD1 deficit. Abnormal wake-up test (WUT) was seen in 38.5% (5/13) and detected 100% (5/5) with POD1 deficit. Most cord alerts occurred during a three-column osteotomy (N = 23/53, 43%); decompression (N = 12), compression (N = 7), exposure (N = 4), and rod placement (N = 14). Interventions were performed in all 53 patients with cord loss and included removing rods/less correction (N = 11), increasing mean arterial pressure alone (N = 10), and further decompression with three-column osteotomy (N = 9). After intervention, IONM data improved in 45(84.9%) patients (Full improvement: N = 28; Partial improvement: 17). For those with full and partial IONM improvement, the POD1 deficit was 10.7% (3/28) and 41.2% (7/17), respectively. For those without any IONM improvement (15.1%, 8/53), 100% (8/8) had a POD1 deficit, P < 0.001. A full or partial improvement in IONM data loss after intraoperative intervention was significantly associated with a lower risk for POD1 deficit with an absolute risk reduction of 89.3% and 58.8%, respectively. All patients without IONM improvement had a POD1 neurologic deficit.

Delayed postoperative neurological deficits from scoliosis correction: a case series and systematic review on clinical characteristics, treatment, prognosis, and recovery.

This study was designed to investigate the clinical features, treatment modalities, and risk factors influencing neurological recovery in patients who underwent scoliosis correction with delayed postoperative neurological deficit (DPND). Three patients with DPND were identified from 2 central databases for descriptive analysis. Furthermore, all DPND cases were retrieved from the PubMed and Embase databases. Neurological function recovery was categorized into complete and incomplete recovery groups based on the American Spinal Injury Association (ASIA) impairment scale. Two patients were classified as type 3, and one was classified as type 2 based on the MRI spinal cord classification. Intraoperative neurophysiological monitoring (IONM) was consistently negative throughout the corrective procedure, and intraoperative wake-up tests were normal. The average time to DPND development was 11.8h (range, 4-18h), and all three patients achieved complete recovery of neurological function after undergoing revision surgery. A total of 14 articles involving 31 patients were included in the literature review. The mean time to onset of DPND was found to be 25.2h, and 85.3% (29/34) of patients experienced DPND within the first 48h postoperatively, with the most common initial symptoms being decreased muscle strength and sensation (26 patients, 83.9%). Regarding neurological function recovery, 14 patients were able to reach ASIA grade E, while 14 patients were not able to reach ASIA grade E. Univariate analysis revealed that preoperative diagnosis (p = 0.004), operative duration (p = 0.017), intraoperative osteotomy method (p = 0.033), level of neurological deficit (p = 0.037) and deficit source (p = 0.0358) were significantly associated with neurological outcomes. Furthermore, multivariate regression analysis indicated a strong correlation between preoperative diagnosis (p = 0.003, OR, 68.633; 95% CI 4.299-1095.657) and neurological prognosis. Our findings indicate that spinal cord ischemic injury was a significant factor for patients experiencing DPND and distraction after corrective surgery may be a predisposing factor for spinal cord ischemia. Additionally, it is important to consider the possibility of DPND when limb numbness and decreased muscle strength occur within 48h after corrective scoliosis surgery. Moreover, emergency surgical intervention is highly recommended for DPND caused by mechanical compression factors with a promising prognosis for neurological function, emphasizing the importance of taking into account preoperative orthopedic diagnoses when evaluating the potential for neurological recovery.

Perioperative management and outcomes for posterior spinal fusion in patients with Friedreich ataxia: A single-center, retrospective study.

Friedreich ataxia is a rare genetic disorder associated with progressive mitochondrial dysfunction leading to widespread sequelae including ataxia, muscle weakness, hypertrophic cardiomyopathy, diabetes mellitus, and neuromuscular scoliosis. Children with Friedreich ataxia are at high risk for periprocedural complications during posterior spinal fusion due to their comorbidities. To describe our single-center perioperative management of patients with Friedreich ataxia undergoing posterior spinal fusion. Adolescent patients with Friedreich ataxia presenting for spinal deformity surgery between 2007 and 2023 were included in this retrospective case series performed at the Children's Hospital of Philadelphia. Perioperative outcomes were reviewed along with preoperative characteristics, intraoperative anesthetic management, and postoperative medical management. Seventeen patients were included in the final analysis. The mean age was 15 ± 2 years old and 47% were female. Preoperatively, 35% were wheelchair dependent, 100% had mild-to-moderate hypertrophic cardiomyopathy with preserved systolic function and no left ventricular outflow tract obstruction, 29% were on cardiac medications, and 29% were on pain medications. Intraoperatively, 53% had transesophageal echocardiography monitoring; 12% had changes in volume status on echo but no changes in function. Numerous combinations of total intravenous anesthetic agents were used, most commonly propofol, remifentanil, and ketamine. Baseline neuromonitoring signals were poor in four patients and one patient lost signals, resulting in 4 (24%) wake-up tests. The majority (75%) were extubated in the operating room. Postoperative complications were high (88%) and ranged from minor complications like nausea/vomiting (18%) to major complications like hypotension/tachycardia (29%) and need for extracorporeal membrane oxygenation support in one patient (6%). Patients with Friedreich ataxia are at high risk for perioperative complications when undergoing posterior spinal fusion and coordinated multidisciplinary care is required at each stage. Future research should focus on the utility of intraoperative echocardiography, optimal anesthetic agent selection, and targeted fluid management to reduce postoperative cardiac complications.

Timing of intraoperative neurophysiological monitoring (IONM) recovery and clinical recovery after termination of pediatric spinal deformity surgery due to loss of IONM signals

Background ContextIntraoperative neurophysiological monitoring (IONM) is used to reduce the risk of spinal cord injury during pediatric spinal deformity surgery. Significant reduction and/or loss of IONM signals without immediate recovery may lead the surgeon to acutely abort the case. The timing of when monitorable signals return remains largely unknown. PurposeThe goal of this study was to investigate the correlation between IONM signal loss, clinical examination, and subsequent normalization of IONM signals after aborted pediatric spinal deformity surgery to help determine when it is safe to return to the operating room. Study Design/SettingThis is a multicenter, multidisciplinary, retrospective study of pediatric patients (<18 years old) undergoing spinal deformity surgery whose surgery was aborted due to a significant reduction or loss of IONM potentials. Patient SampleSixty-six patients less than 18 years old who underwent spinal deformity surgery that was aborted due to IONM signal loss were enrolled into the study. Outcome MeasuresIONM data, operative reports, and clinical examinations were investigated to determine the relationship between IONM loss, clinical examination, recovery of IONM signals, and clinical outcome. MethodsInformation regarding patient demographics, deformity type, clinical history, neurologic and ambulation status, operative details, IONM information (eg, quality of loss [SSEPs, MEPs], laterality, any recovery of signals, etc.), intraoperative wake-up test, postoperative neurologic exam, postoperative imaging, and time to return to the operating were all collected. All factors were analyzed and compared with univariate and multivariate analysis using appropriate statistical analysis. ResultsSixty-six patients were enrolled with a median age of 13 years [IQR 11-14], and the most common sex was female (42/66, 63.6%). Most patients had idiopathic scoliosis (33/66, 50%). The most common causes of IONM loss were screw placement (27/66, 40.9%) followed by rod correction (19/66, 28.8%). All patients had either complete bilateral (39/66, 59.0%), partial bilateral (10/66, 15.2%) or unilateral (17/66, 25.8%) MEP loss leading to termination of the case. Overall, when patients were returned to the operating room 2 weeks postoperatively, nearly 75% (40/55) had monitorable IONM signals. Univariate analysis demonstrated that bilateral SSEP loss (p=.019), bilateral SSEP and MEP loss (p=.022) and delayed clinical neurologic recovery (p=.008) were significantly associated with having unmonitorable IONM signals at repeat surgery. Multivariate regression analysis demonstrated that delayed clinical neurologic recovery (> 72 hours) was significantly associated with unmonitorable IONM signals when returned to the operating room (p=.006). All patients ultimately made a full neurologic recovery. ConclusionsIn children whose spinal deformity surgery was aborted due to intraoperative IONM loss, there was a strong correlation between combined intraoperative SSEP/MEP loss, the magnitude of IONM loss, the timing of clinical recovery, and the time of electrophysiological IONM recovery. The highest likelihood of having a prolonged postoperative neurological deficit and undetectable IONM signals upon return to the OR occurs with bilateral complete loss of SSEPs and MEPs.

Definition, Frequency and Risk Factors for Intra-Operative Spinal Cord Injury: A Knowledge Synthesis.

Mixed-methods approach. Intra-operative spinal cord injury (ISCI) is a devastating complication of spinal surgery. Presently, a uniform definition for ISCI does not exist. Consequently, the reported frequency of ISCI and important risk factors vary in the existing literature. To address these gaps in knowledge, a mixed-methods knowledge synthesis was undertaken. A scoping review was conducted to review the definitions used for ISCI and to ascertain the frequency of ISCI. The definition of ISCI underwent formal review, revision and voting by the Guidelines Development Group (GDG). A systematic review of the literature was conducted to determine the risk factors for ISCI. Based on this systematic review and GDG input, a table was created to summarize the factors deemed to increase the risk for ISCI. All reviews were done according to PRISMA standards and were registered on PROSPERO. The frequency of ISCI ranged from 0 to 61%. Older age, male sex, cardiovascular disease including hypertension, severe myelopathy, blood loss, requirement for osteotomy, coronal deformity angular ratio, and curve magnitude were associated with an increased risk of ISCI. Better pre-operative neurological status and use of intra-operative neuromonitoring (IONM) were associated with a decreased risk of ISCI. The risk factors for ISCI included a rigid thoracic curve with high deformity angular ratio, revision congenital deformity with significant cord compression and myelopathy, extrinsic intradural or extradural lesions with cord compression and myelopathy, intramedullary spinal cord tumor, unstable spine fractures (bilateral facet dislocation and disc herniation), extension distraction injury with ankylosing spondylitis, ossification of posterior longitudinal ligament (OPLL) with severe cord compression, and moderate to severe myelopathy. ISCI has been defined as "a new or worsening neurological deficit attributable to spinal cord dysfunction during spine surgery that is diagnosed intra-operatively via neurophysiologic monitoring or by an intraoperative wake-up test, or immediately post-operatively based on clinical assessment". This paper defines clinical and imaging factors which increase the risk for ISCI and that could assist clinicians in decision making.

The neurological wake-up test in severe pediatric traumatic brain injury: a long term, single-center experience.

To describe the use and outcomes of the neurological wake-up test (NWT) in pediatric severe traumatic brain injury (pTBI). Retrospective single-center observational cohort study. Medical-surgical tertiary pediatric intensive care unit (PICU) in a university medical center and Level 1 Trauma Center. Children younger than 18 years with severe TBI [i.e., Glasgow Coma Scale (GCS) of ≤8] admitted between January 2010 and December 2020. Subjects with non-traumatic brain injury were excluded. Of 168 TBI patients admitted, 36 (21%) met the inclusion criteria. Median age was 8.5 years [2 months to 16 years], 5 patients were younger than 6 months. Median initial Glasgow Coma Scale (GCS) and Glasgow Motor Scale (GMS) was 6 [3-8] and 3 [1-5]. NWTs were initiated in 14 (39%) patients, with 7 (50%) labelled as successful. Fall from a height was the underlying injury mechanism in those seven. NWT-failure occurred in patients admitted after traffic accidents. Sedation use in both NWT-subgroups (successful vs. failure) was comparable. Cause of NWT-failure was non-arousal (71%) or severe agitation (29%). Subjects with NWT failure subsequently had radiological examination (29%), repeat NWT (43%), continuous interruption of sedation (14%) or intracranial pressure (ICP) monitoring (14%). The primary reason for not doing NWTs was intracranial hypertension in 59%. Compared to the NWT-group, the non-NWT group had a higher PRISM III score (18.9 vs. 10.6), lower GCS/GMS at discharge, more associated trauma, and circulatory support. Nine patients (25%) died during their PICU admission, none of them had an NWT. We observed limited use of NWTs in pediatric severe TBI. Patients who failed the NWT were indistinguishable from those without NWT. Both groups were more severely affected compared to the NWT successes. Therefore, our results may indicate that only a select group of severe pTBI patients qualify for the NWT.

Negative pressure suction test: An intraoperative airway maneuver to assess effectiveness of surgical correction of tracheobronchomalacia.

Surgical correction of tracheobronchomalacia (TBM) has evolved greatly over the past decade, with select pediatric institutions establishing dedicated surgery and anesthesia teams to navigate the complexities and challenges of surgical airway repairs. Although anesthetic techniques have evolved internally over many years to improve patient safety and outcomes, many of these methods remain undescribed in literature. In this article, we describe the intraoperative negative pressure suction test. This simulates the negative pressure seen in awake and spontaneously breathing patients, including the higher pressures seen during coughing which induce airway collapse in patients with TBM. Also known as the Munoz maneuver in surgical literature, this test has been performed on over 300 patients since 2015. The negative pressure suction test allows for controlled intraoperative assessment of surgical airway repairs, replaces the need for risky intraoperative wake-up tests, increases the chances of a successful surgical repair, and improves anesthetic management for emergence and extubation. We provide a guide on how to perform the test and videos demonstrating its efficacy in intraoperative airway evaluation. As surgeries to repair TBM become more prevalent in other pediatric institutions, we believe that pediatric patients and anesthesia providers will benefit from the insights and methods described here.

The adjunct use of descending neurogenic-evoked potentials when transcranial motor-evoked potentials degrade into warning criteria in pediatric spinal deformity surgery: minimizing false-positive events.

This studies objective was to evaluate the utility of descending neurogenic-evoked potentials (DNEPs) in the setting of transcranial motor-evoked potentials (TCeMEPs) degradation into warning criteria during pediatric spinal deformity surgery. An institutional spinal cord monitoring database was queried to identify all primary and revision pediatric spinal deformity cases, < / = 21years of age performed from 1/2006 to 12/2021, in which TCeMEPs were the primary motor tract assessment modality which degraded into warning criteria, with subsequent initiation of adjunct DNEPs. Fourteen surgical cases (0.42%; 3351 total cases) in fourteen patients met inclusion criteria. Mean age was 13.2years (7.5-21.3). syndromic (n = 7), kyphosis (n = 3), congenital (n = 2), and idiopathic (n = 2). Three-column osteotomies (3CO)were done in eight patients. TCeMEPs degraded into warning criteria during screw placement (n = 7), 3CO performance/closure (n = 4), or deformity correction (n = 3). DNEPs were present in all cases of warning-criteria TCeMEPs and one case had degradation of DNEPs. Intraoperative Stagnara wake-up tests were performed in only 2/14 cases, with one transient new neurologic deficit (NND). In this specific scenario, DNEPs sensitivity was 50%, specificity 100%, positive predictive value 100%, and negative predictive value 92% to detect aNND. DNEPs were useful in assessing spinal cord function in the setting of TCeMEP data degradation in complex pediatric deformity surgeries. DNEPs demonstrated a higher specificity and positive predictive value in this clinical setting than TCeMEPs when assessing long-term neurologic function after surgery. Based on this small cohort, DNEPs appear to be a useful adjunct modality to TCeMEPs, in this challenging clinical scenario.

Neurological Wake-Up Test for Severe Neurotrauma Patients

A structured assessment of patients with severe traumatic brain injury (TBI) is routinely used in the neurointensive care units. A judicious clinical evaluation of heterogeneous pathologies such as TBI, stroke, and subarachnoid hemorrhage requires training specific to master the fundamental tools of neuro bedside examination. The wake-up test has been a strategy that has emerged as a source of valuable information[1] [2] to know about the progression of these patients and make an adequate correlation between neuromonitoring and neuroradiological imaging.[3]

The effect of dexmedetomidine on wake-up test quality when muscle relaxants are not used: A randomized control trial.

Stagnara wake-up test is a simple reproducible neuromonitoring method during spinal surgery which replaces the evoked potential monitoring in the absence of neuromonitoring facilities. Dexmedetomidine (DEX) effect on the intraoperative wake-up test is still unclear. The present study was conducted to evaluate the effectiveness of DEX on the quality of wake-up test during spinal correction surgery. A randomized controlled study was carried out over 62 patients randomized into two equal groups planned for elective minimally invasive corrective spine surgery. Instead of atracurium administration in the control group, patients in the experimental group were administered titrated continuous intravenous infusion of DEX at a dose of 0.2-0.7 μg/kg/hour. Lidocaine 2% spray around the vocal cords was done in both the groups to facilitate toleration of the endotracheal tube. The DEX group showed statistically significant longer duration and better quality of the wake-up test. Statistically significant better haemodynamic state, a lower amount of intraoperative sedatives and higher amount of intraoperative analgesics were also evident in the DEX group. The postoperative Ramsay sedation scale was significantly lower in the DEX group just after extubation. The DEX use has shown an improving effect on the wake-up test quality, with slightly prolonged wake-up time. The present work supports the use of DEX as an adjuvant drug alleviating the need for the neuromuscular blockade, inducing a better haemodynamic profile, exhibiting better sedation and improving the awakening condition.

Deformity angular ratio is associated with neuromonitoring changes without a vertebral column resection: spinal deformity is more influential than type of surgery

PurposeThe purpose of this study is to investigate the effect of the deformity angular ratio (DAR) on intra-operative neuromonitoring (IONM) signal changes during posterior spinal fusion (PSF) without vertebral column resection (VCR).MethodsRetrospective review of severe pediatric spinal deformity patients treated with PSF without VCR or three-column osteotomy from 2008 to 2018. Exclusion criteria were prior instrumentation, lack of IONM, and incomplete radiographic data. Coronal DAR (C-DAR), sagittal DAR (S-DAR), and total DAR (T-DAR) were calculated and compared between patients with IONM signal loss and those without.ResultsTwo hundred and fifty-three patients met inclusion criteria. Forty-seven of two hundred and fifty-three (19%) patients had IONM signal loss. Intra-operative wake-up test was performed in seven cases; three of seven (43%) had a neurological deficit on wake-up test. All neurological deficits resolved at a mean of 41 days postop. IONM loss was associated with increased kyphosis (p = 0.003) and was not associated with Cobb angle (p = 0.16). S-DAR (p = 0.03) and T-DAR (p = 0.005) were associated with IONM signal loss but C-DAR was not (p = 0.06). Increased incidence of IONM signal loss was seen with S-DAR > 7 (p = 0.02) or T-DAR > 27 (p = 0.02). Twenty-four of ninety-two (26%) patients with S-DAR > 7 had IONM signal loss compared to twenty-three of one hundred and sixty-one (14%) with S-DAR ≤ 7 (OR, 2.1; 95% CI, 1.1–4.0). Seven of sixteen (44%) patients with T-DAR > 27 had signal loss compared to forty of two hundred and thirty-seven (17%) patients with T-DAR ≤ 27 (OR, 3.8; 95% CI, 1.3–10.9).ConclusionPatients with S-DAR > 7 or T-DAR > 27 have a higher risk of IONM loss during pediatric PSF even in the absence of a VCR or three-column osteotomies.Level of evidence II.

The relevance of the wake-up test in scoliosis surgery: A narrative review

The corrective scoliosis surgery is associated with many complications; the neurologic complication is one of them. It is very important to assess spinal cord integrity intraoperatively to avoid postoperative damage and have a good outcome. Wake-up test was the standard of care in old generations but now with the availability of advanced neurophysiologic monitoring somatosensory and motor-evoked potentials; the relevance of wake-up test is questionable. This review aimed to assess the relevance of wake-up test in scoliosis surgery with availability of advanced technology. Comprehensive literature search was performed in PubMed, Google Search and Scopus, EndNote X6 version, and the keywords used for the search were scoliosis, neurophysiologic monitoring, and wake-up test. The different study results were interpreted to come to conclusion. This review gives us a detailed idea of the different tests available and pitfalls with each and finally what should be our stand. The review highlighted the good collaboration between surgeon, anesthesiologist, and neurologist to conclude the results of the tests of neurophysiologic monitoring. Intraoperative neurologic monitoring improves postoperative outcome. Wake-up test is only and strongly recommended, in case of unavailability of advanced monitoring, confusion on test results, and persistent signal reduction.

Dexmedetomidine dosage in critically ill patients undergoing intraoperative wake-up test

Objective:The aim of this study was to find the optimum dosage of dexmedetomidine in Spinal Orthopedic Scoliosis Correction Surgery when used in combination with propofol and remifentanil in American Society of Anesthesiologists (ASA) III patients with severe scoliosis undergoing intraoperative wake-up test.Materials and methods:We selected a total of 60 ASA III ≤40 years old patients who underwent Spinal Orthopedic Scoliosis Correction Surgery (SOSCS) and randomized them into groups A, B, and C. Group A was administered 0.2 μg/(kg·h) of dexmedetomidine, group B 0.3 μg/(kg·h), and group C 0.4 μg/(kg·h). The main parameters monitored were: wake-up time; wake-up quality; adverse effects that occur while the patient is awake; postoperative awareness of intraoperative wake-up test; heart rate (HR); mean arterial pressure (MAP); and oxygen saturation (SpO2). Values of these parameters were monitored at 7 timestamps separated by 5 minutes >30 minutes.Results:Group B had a higher MAP at 10 minutes before wake-up (P = .03) and at the moment of wake-up (P = .04) than group A. The Wake-up time of group A was 14.95 ± 7.42 minutes, group B was 14.7 ± 6.52 minutes, which was significantly shorter than that of group C 21.3 ± 10.02 minutes (P = .02). The wake-up quality was excellent. All other parameters had no significant statistical differences.Conclusion:Doses of 0.2 to 0.3 μg/(kg·h) have shorter wake-up time and fewer hemodynamic fluctuations compared to 0.4 μg/(kg·h).

Intraoperative Neurophysiological Monitoring Alerts During Three-Column Osteotomy: Incidence and Risk Factors

To analyze the incidence and risk factors of intraoperative neurophysiological monitoring (IONM) alerts in patients undergoing three-column osteotomy. A total of 551 patients (340 males and 211 females) with an average age of 31.9 years undergoing posterior 3-column osteotomy were retrospectively reviewed. The coronal Cobb angle of main curve and sagittal global kyphosis were measured on preoperative standing whole spinal x-rays. The Frankel scores at preoperation, postoperation, and the last follow-up were recorded and applied for assessment of neurologic status. Surgical procedures and other factors associated with IONM alerts were analyzed. A total of 98 (17.8%) IONM alerts were reported during surgery, including 82 somatosensory evoked potential alerts and 91 motor evoked potential alerts. Positive wake-up test was revealed in 57 patients (10.3%) even after prompt managements, and new neurologic deficits were observed in 50 patients (9.1%) at immediate postoperation. Of the 50 patients with new neurologic deficits at postoperation, the Frankel scores were A in 5 patients, B in 4, C in 9, and D in 32. The χ2 test showed that patients with congenital deformities, global kyphosis >90°, vertebral column resection procedure, cervicothoracic/thoracic osteotomy, blood loss >3,000 mL, and preoperative neurologic deficit were at a higher risk of IONM alerts. The incidence of IONM alerts in patients undergoing 3-column osteotomy was 17.8%. Congenital deformities, global kyphosis >90°, vertebral column resection, cervicothoracic/thoracic osteotomy, blood loss >3,000 mL, and preoperative neurologic deficit indicated high risk of IONM alerts.

Unusual Airway Obstruction during General Anesthesia following Endotracheal Tube Cuff Herniation; A Case Report

Abstract Background: Airway management is always of great concern for anesthesiologists especially in the prone position. Utilizing an Armored endotracheal tube is considered to be safe in such patients. Cases Report: In this current case, we introduce a patient undergoing a wake-up test during spinal surgery who suffered from hypoventilation at the end of surgery. His condition improved only after extubation. After extubation, we confronted a herniated cuff that was not deflated, although we tried twice. We concluded that the patient's respiratory effort against obstructed airway produced a negative pressure, which made the cuff herniated, resulting in airway obstruction. Moreover, the patient biting the tube during the wake-up test damaged the tube and cuff deflation pathway. Conclusion: It is important to consider cuff herniation as a cause of obstruction when other possible etiologies are ruled out.

Intraoperative Neuromonitoring Auxiliary Significance of DNEP for MEP-positive Event During Severe Spinal Deformity Surgery.

Study Design:This was a retrospective analysis.Objective:The objective of this study was to assess the intraoperative neuromonitoring auxiliary significance of descending neurogenic–evoked potential (DNEP) for motor-evoked potential (MEP) during severe spinal deformity surgery when MEP-positive event occurs.Summary of Background Data:MEP detection is the most widely applied neurological monitoring technique in spinal deformity surgery. MEP is quite vulnerable to anesthesia, blood pressure, and other intraoperative factors, leading to a high false-positive rate of MEP (3.2%–45.0%), which has greatly interfered with the surgical process. At present, the widely used “presence-or-absence” alarm criteria of MEP is not enough to solve the problem of false positive of MEP.Methods:A total of 205 cases undergoing severe spinal deformity correction were retrospectively studied. Overall, 74 MEP-positive cases were classified as 2 subgroups: DNEP (+) and DNEP (−) groups. The MEP recovery, wake-up test, and Frankle grade were used to assess the neurological functions. The perioperative and long-term neurological outcomes were assessed.Results:There were significant differences in preoperative scoliosis angle and kyphosis angle between DNEP (−) and DNEP (+) groups. Patients in DNEP (−) group showed more MEP improvement (81.5%), compared with the DNEP (+) group (53.2%). The Wake-up test showed 59.3% motor function deficit cases in DNEP (−) group, which was lower than the 87.2% in DNEP (+) group. More patients in DNEP (−) group had normal nerve function (Frankel level E) than those in DNEP (+) group immediately after surgery, as well as at follow-up.Conclusions:MEP-positive cases with intraoperative DNEP (−) showed superior prognosis after severe spinal deformity surgery. Intraoperative DNEP could be regarded as an important quantitative tool to assist MEP to monitor neurological injury and can serve as a temporary substitution monitoring technique after MEP is lost.

Effects of preoperative intravenous amantadine sulfate infusion on wake up test duration and postoperative opioid consumption in adolescents undergoing spine corrective surgery

BackgroundAmantadine sulfate is both a dopamine agonist and N-methyle-D-Aspartate (NMDA) antagonist which can augment the levels of dopamine in the striate body by triggering dopamine release and inhibiting dopamine reuptake. This study evaluated the effects of amantadine sulfate as a dopamine agonist on intraoperative wake up test duration and as a NMDA antagonist on cumulative opioid consumption 48 h after surgery. MethodsA randomized controlled double blind study, where 60 ASA class I and/or II patients of both sexes, planned for spine deformity corrective surgery were enrolled and divided into two groups (30 patients each): Group A received intravenous (IV) amantadine sulfate infusion (200 mg), and Group B received Ringer's lactate IV infusion. ResultsForty-eight hours after surgery, morphine consumption in group A was significantly lower than that in Group B (21.24 ± 1.1 vs. 30.41 ± 2.12 P < 0.001). Dynamic visual analog scale score was lower group A than that in group B (0.8 ± 0.71 vs. 2.7 ± 0.84 P < 0.001). Moreover, anesthetic consumption in group A was lower than that in group B; however, no statistical difference in wake-up test duration or recovery time from anesthesia was found between both groups. ConclusionsPreoperative administration of amantadine sulfate decreases postoperative morphine consumption and dynamic VAS score in patients undergoing corrective spine surgery. However, despite being a dopamine agonist, amantadine has no effect on wake- up test duration.

Neurologic Assessment of the Neurocritical Care Patient.

Sedation is a ubiquitous practice in ICUs and NCCUs. It has the benefit of reducing cerebral energy demands, but also precludes an accurate neurologic assessment. Because of this, sedation is intermittently stopped for the purposes of a neurologic assessment, which is termed a neurologic wake-up test (NWT). NWTs are considered to be the gold-standard in continued assessment of brain-injured patients under sedation. NWTs also produce an acute stress response that is accompanied by elevations in blood pressure, respiratory rate, heart rate, and ICP. Utilization of cerebral microdialysis and brain tissue oxygen monitoring in small cohorts of brain-injured patients suggests that this is not mirrored by alterations in cerebral metabolism, and seldom affects oxygenation. The hard contraindications for the NWT are preexisting intracranial hypertension, barbiturate treatment, status epilepticus, and hyperthermia. However, hemodynamic instability, sedative use for primary ICP control, and sedative use for severe agitation or respiratory distress are considered significant safety concerns. Despite ubiquitous recommendation, it is not clear if additional clinically relevant information is gleaned through its use, especially with the contemporaneous utilization of multimodality monitoring. Various monitoring modalities provide unique and pertinent information about neurologic function, however, their role in improving patient outcomes and guiding treatment plans has not been fully elucidated. There is a paucity of information pertaining to the optimal frequency of NWTs, and if it differs based on type of injury. Only one concrete recommendation was found in the literature, exemplifying the uncertainty surrounding its utility. The most common sedative used and recommended is propofol because of its rapid onset, short duration, and reduction of cerebral energy requirements. Dexmedetomidine may be employed to facilitate serial NWTs, and should always be used in the non-intubated patient or if propofol infusion syndrome (PRIS) develops. Midazolam is not recommended due to tissue accumulation and residual sedation confounding a reliable NWT. Thus, NWTs are well-tolerated in selected patients and remain recommended as the gold-standard for continued neuromonitoring. Predicated upon one expert panel, they should be performed at least one time per day. Propofol or dexmedetomidine are the main sedative choices, both enabling a rapid awakening and consistent NWT.

Washout and Awakening Times after Inhaled Sedation of Critically Ill Patients: Desflurane Versus Isoflurane

In recent years, inhaled sedation has been increasingly used in the intensive care unit (ICU). The aim of this prospective, controlled trial was to compare washout and awakening times after long term sedation with desflurane and isoflurane both administered with the Mirus™ system (TIM GmbH, Koblenz, Germany). Twenty-one consecutive critically ill patients were alternately allocated to the two study groups, obtaining inhaled sedation with either desflurane or isoflurane. After 24 h study sedation, anesthetic washout curves were recorded, and a standardized wake-up test was performed. The primary outcome measure was the time required to decrease the endtidal concentration to 50% (T50%). Secondary outcome measures were T80% and awakening times (all extremities moved, RASS −2). Decrement times (min) (desflurane versus isoflurane, median (1st quartile—3rd quartile)) (T50%: 0.3 (0.3–0.4) vs. 1.3 (0.4–2.3), log-rank test P = 0.002; P80%: 2.5 (2–5.9) vs. 12.1 (5.1–20.2), P = 0.022) and awakening times (to RASS −2: 7.5 (5.5–8.8) vs. 41.0 (24.5–43.0), P = 0.007; all extremities moved: 5.0 (4.0–8.5) vs. 13.0 (8.0–41.25), P = 0.037) were significantly shorter after desflurane compared to isoflurane. The use of desflurane with the Mirus™ system significantly shortens the washout times and leads to faster awakening after sedation of critically ill patients.