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Despite decades of clinical usage, selection of patients with drug resistant epilepsy who are most likely to benefit from vagus nerve stimulation (VNS) remains a challenge. The mechanism of action of VNS is dependent upon afferent brainstem circuitry, which comprises a critical component of the Vagus Afferent Network (VagAN). To evaluate the association between brainstem afferent circuitry and seizure response, we retrospectively collected intraoperative data from sub-cortical recordings of somatosensory evoked potentials (SSEP) in 7 children with focal drug resistant epilepsy who had failed epilepsy surgery and subsequently underwent VNS. Using multivariate linear regression, we demonstrate a robust negative association between SSEP amplitude (p < 0.01), and seizure reduction. There was no association between SSEP latency and seizure outcomes. Our findings provide novel insights into the mechanism of VNS and inform our understanding of the importance of brainstem afferent circuitry within the VagAN for seizure responsiveness following VNS. [ABSTRACT FROM AUTHOR]

Background: Awake craniotomy with direct cortical stimulation and mapping is the gold standard for resection of lesions near eloquent brain areas, as it can maximize the extent of resection while minimizing the risk of neurological damage. In contrast to the adult population, only small series of awake craniotomies have been reported in children. Aims: The aim of our study is to establish the feasibility of awake craniotomy in the pediatric population. Methods: We performed a retrospective observational study of children undergoing a supratentorial awake craniotomy between January 2009 and April 2019 in a pediatric tertiary care center. Our primary outcome was feasibility of awake craniotomy, defined as the ability to complete the procedure without conversion to general anesthesia. Our secondary outcomes were the incidence of serious intraoperative complications and the mapping completion rate. Results: Thirty procedures were performed in 28 children: 12 females and 16 males. The median age was 14 years (range 7‐17). The primary diagnosis was tumor (83.3%), epilepsy (13.3%), and arterio‐venous malformation (3.3%). The anesthetic techniques were asleep‐awake‐asleep (96.7%) and conscious sedation (3.3%), all cases supplemented with scalp block and pin‐site infiltration. Awake craniotomy was feasible in 29 cases (96.7%), one patient converted to general anesthesia due to agitation. Serious complications occurred in six patients: agitation (6.7%), seizures (3.3%), increased intracranial pressure (3.3%), respiratory depression (3.3%), and bradycardia (3.3%). All complications were quickly resolved and without major consequences. Cortical mapping was completed in 96.6% cases. New neurological deficits occurred in six patients (20%)—moderate in one case and mild in 5—being all absent at 6 months of follow‐up. Conclusion: Awake craniotomy with intraoperative mapping can be successfully performed in children. Adequate patient selection and close cooperation between neurosurgeons, anesthesiologists, neuropsychologists, and neurophysiologists is paramount. Further studies are needed to determine the best anesthetic technique in this population group. [ABSTRACT FROM AUTHOR]

Study Design: Development of a clinical practice guideline following the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) process. Objective: The objectives of this study were to develop guidelines that outline the utility of intraoperative neuromonitoring (IONM) to detect intraoperative spinal cord injury (ISCI) among patients undergoing spine surgery, to define a subset of patients undergoing spine surgery at higher risk for ISCI and to develop protocols to prevent, diagnose, and manage ISCI. Methods: All systematic reviews were performed according to PRISMA standards and registered on PROSPERO. A multidisciplinary, international Guidelines Development Group (GDG) reviewed and discussed the evidence using GRADE protocols. Consensus was defined by 80% agreement among GDG members. A systematic review and diagnostic test accuracy (DTA) meta-analysis was performed to synthesize pooled evidence on the diagnostic accuracy of IONM to detect ISCI among patients undergoing spinal surgery. The IONM modalities evaluated included somatosensory evoked potentials (SSEPs), motor evoked potentials (MEPs), electromyography (EMG), and multimodal neuromonitoring. Utilizing this knowledge and their clinical experience, the multidisciplinary GDG created recommendations for the use of IONM to identify ISCI in patients undergoing spine surgery. The evidence related to existing care pathways to manage ISCI was summarized and based on this a novel AO Spine-PRAXIS care pathway was created. Results: Our recommendations are as follows: (1) We recommend that intraoperative neurophysiological monitoring be employed for high risk patients undergoing spine surgery, and (2) We suggest that patients at "high risk" for ISCI during spine surgery be proactively identified, that after identification of such patients, multi-disciplinary team discussions be undertaken to manage patients, and that an intraoperative protocol including the use of IONM be implemented. A care pathway for the prevention, diagnosis, and management of ISCI has been developed by the GDG. Conclusion: We anticipate that these guidelines will promote the use of IONM to detect and manage ISCI, and promote the use of preoperative and intraoperative checklists by surgeons and other team members for high risk patients undergoing spine surgery. We welcome teams to implement and evaluate the care pathway created by our GDG. [ABSTRACT FROM AUTHOR]

Study Design: Scoping Review. Objective: To review the literature and summarize information on checklists and algorithms for responding to intraoperative neuromonitoring (IONM) alerts and management of intraoperative spinal cord injuries (ISCIs). Methods: MEDLINE® was searched from inception through January 26, 2022 as were sources of grey literature. We attempted to obtain guidelines and/or consensus statements from the following sources: American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM), American Academy of Neurology (AAN), American Clinical Neurophysiology Society, NASS (North American Spine Society), and other spine surgery organizations. Results: Of 16 studies reporting on management strategies for ISCIs, two were publications of consensus meetings which were conducted according to the Delphi method and eight were retrospective cohort studies. The remaining six studies were narrative reviews that proposed intraoperative checklists and management strategies for IONM alerts. Of note, 56% of included studies focused only on patients undergoing spinal deformity surgery. Intraoperative considerations and measures taken in the event of an ISCI are divided and reported in three categories of i) Anesthesiologic, ii) Neurophysiological/Technical, and iii) Surgical management strategies. Conclusion: There is a paucity of literature on comparative effectiveness and harms of management strategies in response to an IONM alert and possible ISCI. There is a pressing need to develop a standardized checklist and care pathway to avoid and minimize the risk of postoperative neurologic sequelae. [ABSTRACT FROM AUTHOR]

BACKGROUND: Inhalational anesthetic effects on upper airway muscle activity in children are largely unknown. The authors tested the hypothesis that phasic inspiratory genioglossus and palatoglossus activity increases during recovery from sevoflurane anesthesia in a dose-dependent manner in children. METHODS: Sixteen children, aged 2.0 to 6.9 yr, scheduled for elective urological surgery were studied. Electromyogram recordings were acquired using intramuscular needle electrodes during spontaneous ventilation. After a 15-min period of equilibration, electromyogram activity was recorded over 30 s at each of three end-tidal concentrations, 1.5, 1.0, and 0.5 minimum alveolar concentration (MAC), administered in sequence. RESULTS: Phasic genioglossus activity was noted in four children at 1.5 MAC, five at 1.0 MAC, and six children at 0.5 MAC sevoflurane. Phasic palatoglossus activity was noted in 4 children at 1.5 MAC, 6 at 1.0 MAC, and 10 children at 0.5 MAC sevoflurane. Both the proportion of children exhibiting phasic activity, and the magnitude of phasic activity increased during recovery from anesthesia. For the genioglossus, decreasing the depth of sevoflurane anesthesia from 1.5 to 1.0 MAC increased phasic activity by approximately 35% and a further decrease to 0.5 MAC more than doubled activity (median [range] at 1.5 and 0.5 MAC: 2.7 [mu]V [0 to 4.0 [mu]V] and 8.6 [mu]V [3.2 to 17.6], respectively; P = 0.029). A similar dose-related increase was recorded at the palatoglossus (P = 0.0002). CONCLUSIONS: Genioglossus and palatoglossus activity increases during recovery from sevoflurane anesthesia in a dose-dependent manner over the clinical range of sevoflurane concentrations in children. [ABSTRACT FROM AUTHOR]

Direct cortical stimulation in commonly used for the accurate localization of the motor cortex but the electrical threshold stimulation parameters with this technique had not been fully established. A retrospective review of 15 cases of pediatric surgical cases were performed. The patients consisted of nine male patients and six female patients with age range from 2 to 18 years (mean: 10.8 years; median: 14 years). The most common pathology was cortical dysplasia (nine cases). Stimulation was performed with a train of five stimulations (range five–seven stimulations; <5% of stimulations required more than five stimulations) applied, each train of 50 μs pulse duration, with an interstimulus interval of 1.1 msec. Stimulation intensity commenced at 25 V and this was increased at 5–10 V increments until motor evoked potentials waveforms of sufficient duration and morphology were consistently generated. Monopolar electrical stimulation threshold for intraoperative motor cortical mapping were found to be more consistent in the upper limb compared to lower limb and facial muscles. Evoked responses from the extensor digitorium communis had the highest recorded rate (83.7%) and required the lowest stimulation voltage (36.0 V). The stimulation voltage was found to be statistically significant compared to threshold values for abductor hallucis, tibialis anterior, deltoid, and orbicularis oris with respective p values of 0.006, 0.021, 0,027, and 0.015. There was also a distinct trend that patients with cortical dysplasia/tuberous sclerosis have higher stimulation thresholds when compared to other pathology ( p = 0.067). Monopolar electrical stimulation threshold for intraoperative motor cortical mapping were more consistent in the upper limb compared to lower limb and facial muscles. Evoked responses from the extensor digitorium communis had the highest recorded rate and required the lowest stimulation voltage. There was also a distinct trend that patients with cortical dysplasia/tuberous sclerosis have higher stimulation thresholds. [ABSTRACT FROM AUTHOR]

Magnetoencephalography (MEG) data analyzed with novel spatial filtering methods, namely event-related beamforming (ERB), have shown success in localizing hand motor areas in healthy adults and in a group of pediatric patients with peri-Rolandic tumors. The validity of this method to localize the primary motor field in a pediatric tumor case was confirmed by intraoperative direct cortical stimulation. Currently, the reliability of this method has not been demonstrated. We report on a 16-year-old boy with localization-related epilepsy originating from his right hemisphere sensory cortex. Hand motor and sensory areas were identified preoperatively by ERB analysis of MEG data. The patient underwent invasive monitoring which localized the epileptic focus to right postcentral gyrus, immediately posterior to the MEG motor area and adjacent to the MEG sensory area. The patient received a gyrectomy of sensory cortex guided by intraoperative direct cortical stimulation to ensure sparing of hand motor cortex. Replication of the MEG motor mapping protocol postoperatively demonstrated reliable localization of the motor and sensory areas. We also discuss caveats for future applications of this protocol. Copyright © 2009 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

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Background: Presurgical functional mapping using magnetoencephalography (MEG) has been performed for somatosensory, auditory and visual functions; however, the traditional analysis method utilizing dipole source analysis has some inherent limitations when applied to the mapping of cortical motor areas. Recently, a novel source reconstruction algorithm [event-related synthetic aperture magnetometry (erSAM)] has demonstrated success for the localization of motor function in healthy adults. We applied this technique to preoperatively map motor function in a young patient. We then confirmed our mapping with direct cortical stimulation intraoperatively. Methods: This is a case report of an 8-year-old girl with right hand and arm weakness and poor right hand motor control secondary to a left peri-rolandic tumor. Preoperatively, whole-head MEG was recorded while the patient performed a self-paced button pressing task. Cortical activity associated with the onset of movement was localized to the right hand precentral gyrus superior and medial to the tumor using erSAM, while sensory function was localized posterior to the tumor on the postcentral gyrus. Results: Intraoperative direct cortical stimulation of the motor area identified by MEG resulted in electromyographic activation of intrinsic muscles of the contralateral hand exclusively. Conclusions: This is the first report of a case where direct cortical stimulation has confirmed a motor cortical location identified by the erSAM method. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

STUDY DESIGN.: Retrospective review of prospectively collected data on the neuromonitoring changes recorded during a consecutive series of cord level 3-column posterior spinal osteotomies for the correction of rigid pediatric spinal deformities in children between 2005 and 2012. OBJECTIVE.: To review the neuromonitoring changes observed during the performance of these procedures, to highlight the high-risk steps, and to describe actions taken to avert major neurological injury. SUMMARY OF BACKGROUND DATA.: Significant motor evoked potentials (MEP) changes are common during the performance of spinal osteotomies in children. The real-time intraoperative information provided by MEPs can provide the necessary information to direct key surgical decisions. METHODS.: The neuromonitoring changes occurring during the performance of 37 3-column, cord level, posterior spinal osteotomies in 28 patients were recorded. The procedures were divided, for comparative purposes, into 2 groups based on the presence or absence of alerts. A decrease in somatosensory evoked potentials and transcranial MEPs greater than 50% of baseline was considered an alert. Alerts were classified chronologically as type I: prior to decompression, type II: occurring during decompression and bone resection, type III: occurring after osteotomy closure. RESULTS.: Somatosensory evoked potential alerts occurred in 3 patients, all of whom had significant MEP alerts. There were 2 type I, 15 type II, and 6 type III MEP alerts. Increasing blood pressure improved MEPs in all with the exception of 8 type II and 4 type III. The unresponsive 8 type II alerts were treated with osteotomy closure with the expectation that spinal shortening would decompress the spinal cord and improve spinal cord perfusion. The unresponsive 4 type III alerts all responded to reopening, manipulation, and subsequent reclosure of the osteotomy either with a cage or less correction. There were 5 immediate postoperative motor deficits. No patient had a permanent deficit. CONCLUSION.: Changes unresponsive to increasing blood pressure occurring during decompression and bone resection (type II) responded well to osteotomy closure. Unresponsive changes during osteotomy closure (type III) were treated successfully with opening the osteotomy, cage adjustment, and less correction.Level of Evidence: 4. [ABSTRACT FROM AUTHOR]

BACKGROUND CONTEXT Traditional methods of neuromonitoring for spinal deformity cases lack accuracy and reproducibility in monitoring for high grade spondylolisthesis. Free run electromyography (EMG) has not been shown to be accurate in detecting radicular injuries in lumbar degenerative surgeries. PURPOSE The purpose of this project is to introduce direct nerve stimulation as a novel alternative to nerve root monitoring in the reduction of high grade spondylolisthesis. METHODS Prospectively collected intraoperative neuromonitoring data including MEP, SSEP and free run EMG, was collected on pediatric patients undergoing posterior reductions for high grade L5 or S1 spondylolisthesis. A fourth modality using direct nerve root stimulation (DNS) of the L5 and S1 nerve roots was recorded by placing a stimulator directly on the exposed nerve root and recording threshold stimulus. Along with the other modalities, DNS was carried out prior to reduction, following all reduction maneuvers and prior to closure. RESULTS Five patients with high grade spondylolisthesis were analyzed, four with Grade IV and one with Grade V. All patients had positive bilateral straight leg raises. Four of 5 patients had intact preoperative lower extremity motor examinations, with one patient having left-sided 4/5 EHL weakness. Three patients did not have any neuromonitoring alerts during their surgical procedure. Their average change in threshold value from baseline to final stimulation in these cases for the L5 nerve root was 1.3 mA. Two patients had intraoperative alerts of MEPs, SSEPs and EMGs which resulted in greater nerve root stimulation threshold values at closing compared to baseline. One patient showed a three-fold increase in DNS threshold while a second patient had a 25-30-fold increase. In both cases, further nerve root exploration and decompression was performed. Both cases resulted in immediate postoperative neurologic deficits in bilateral ankle dorsiflexion. CONCLUSIONS After establishing a prereduction threshold of direct nerve stimulation, increases in DNS threshold were associated with postoperative neurologic deficits in cases of posterior reduction of high grade spondylolisthesis. DNS provided an accurate measure of nerve function in this series. Recognizing increases in DNS thresholds intraoperatively can alert the surgeon to potential real time nerve injuries. A larger multicenter series can help determine the utility of this technique. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]