Abstracts From the 50th Annual Meeting of the Society for Neuroscience in Anesthesiology and Critical Care, September 8-11, 2022

[SNACC-1] A Brush with Danger: An Emergent Traumatic Transoral Intradural Toothbrush Perforation with Superior Cervical Laminectomy and Dural Repair

Kiel A, Brown M, Abcejo, A. Mayo Clinic, Rochester, Minnesota, United States.

A previously healthy 40-year-old male was transferred by flight emergency medical services from an outside hospital after falling while brushing his teeth with an electric toothbrush while acutely alcohol intoxicated. The toothbrush impaled transorally into posterior tissue. After falling, the patient was able to remove the handle but unable to remove the toothbrush head from his mouth. Apart from limited speech determined to be due to pain, he had a normal neurological exam on presentation and patent airway. Computerized tomography (CT) scan revealed the toothbrush head extending from the left side of the oral cavity through the left C2-3 foramen with the bristles causing spinal cord and thecal sac deviation. Additional pertinent findings included significant pharyngeal and prevertebral soft tissue edema, left anterior C2 displacement, and posttraumatic gas within the spinal canal and along the cerebellar vermis. Anesthesiology, Neurosurgery, and Otolaryngology established the initial plan to perform an awake tracheostomy followed by C2-3 laminectomy, duraplasty, and removal of the toothbrush head by posterior approach. Awake tracheostomy was performed with moderate sedation via dexmedetomidine and fentanyl, enhanced with a blood ethanol level of 231 mg/dL. Extreme care was taken to maintain oxygenation and minimize neck movement during awake tracheostomy. Following awake tracheostomy, general anesthesia was induced and maintained with a total intravenous anesthetic with propofol and remifentanil. The procedure was completed successfully, however, the following morning he had a precipitous neurologic decline and required emergent C1 laminectomy, suboccipital decompression, removal of necrotic cerebellar tissue, and placement of an external ventricular drain (EVD). He was discharged to inpatient rehabilitation 19 days later and discharged home after an additional 12 days. At time of discharge, he had slight left sided cerebellar symptoms including intermittent dizziness when walking, difficulty with balance in some situations, and finger to nose dysmetria. Except for generalized deconditioning, he was back to his baseline functional status. This case highlights strategies used to obtain a protected airway in the context of complex, anatomically undifferentiated pharyngeal and neck trauma.

[SNACC-2] A case report: Rapid decrease of cerebral oxygen saturation after the cervical branch reconstruction of Total Aortic Arch Replacement indicated a true lumen collapse of the right carotid artery

Miura S*, Yoshitani K†, Ohnishi Y†. Ibaraki Prefectual Central Hospital, Ibaraki Cancer Center, Matsudo, Chiba, Japan*. National Cerebral & Cardiovascular Center, Suita, Osaka, Japan†

Malperfusion of the carotid artery in acute aortic dissection is a severe complication and worsens prognosis. Intraoperatively, the dissection may extend into the intact carotid artery preoperatively, causing a sudden decrease in cerebral perfusion pressure. We present the case that regional cerebral oxygen saturation (rSO2) indicated the acute occlusion of the carotid artery due to the collapse of the true lumen. The rSO2 successfully recovered after re-anastomosis of the carotid artery.

Case: A 78-year-old man with Debakey I acute aortic dissection underwent emergent Total Aortic Arch Replacement. Thoracic enhanced computed tomography showed that the lesion of aortic dissection was limited to the aortic arch. Neuro monitoring included rSO2 measured by O3 and Sedline (Mashimo, Irvine, CA, USA). After heparin administration for cardiopulmonary bypass (CPB), rSO2 suddenly decreased from 60 to 20% on the right side. Transesophageal echocardiography demonstrated that aortic dissection extended to the descending aorta and the carotid artery. After starting the cardiopulmonary bypass, body temperature was cooled to 18 Celsius for brain protection. The left and right carotid, and the left subclavian artery were reconstructed during the selective cerebra perfusion, in which rSO2 was around 65%. After coming off the CPB, rSO2 suddenly decreased to 30% on the right side. Carotid artery sonography indicated the collapse of the right carotid artery (Figure 1 and 2). We suspected reperfusion from the reentry of the distal side compressed the true lumen of the proximal side of the carotid artery. The surgeon decided to perfume re-anastomosis of the left carotid artery. After the re-anastomosis of the right carotid artery at the distal side, rSO2 increased to 60%.

F1FIGURE 1:

The blood flow of the right carotid artery by carotid ultrasoundgraphy.

F2FIGURE 2:

The blood flow of the right carotid artery after comming off cardiopulmonary bypass.

Conclusion: rSO2 successfully indicated a true lumen collapse of the right carotid artery due to reperfusion from the reentry of the distal side. rSO2 monitoring is helpful and would be recommended during acute aortic dissection.

[SNACC-3] A comparison of regional cerebral oxygen saturation using near-infrared spectroscopy (NIRS) of NIRO-200NX and O3 in patients with pulmonary endarterectomy

Masuda S*, Yoshitani K*, Tsukinaga K†, Nakano Y*. National Cerebral & Cardiovascular Center, Suita, Osaka, Japan*. Iwate Medical University, Morioka, Iwate, Japan†

Background: Several devices are now available for measuring regional cerebral oxygen saturation using near-infrared spectroscopy. There were wide varieties in regional cerebral oxygen saturation among several devices (1). Among devices, NIRO-200NXⓇ (Hamamatsu Photonics, Hamamatsu, Japan) has had small contamination of the skull and cerebrospinal fluid layer compared with INVOS (2). Also, O3Ⓡ (Masimo, Neuchatel, Switzerland) had received Food Drug Administration (FDA) approval for use on infant and neonatal patients (<10 kg) and has been used widely in addition in adult patients. However, no studies have investigated the difference between these two devices during deep hypothermic circulatory cardiac arrest to our best knowledge. Therefore, we compared the cerebral oxygen saturation of NIRO-200 NX (TOI) and O3(rSO2).

Methods: This study was approved by the Ethics Committee of our institute. We compared TOI with rSO2 in patients with chronic thromboembolic pulmonary hypertension (CTEPH) undergoing pulmonary endarterectomy (PEA), which requires deep hypothermic circulatory arrest (DHCA) to prevent the backflow of blood from the pulmonary artery several times for approximately 20 minutes. Both the NIRO-200NX sensor and O3 sensor were attached to the forehead to measure cerebral oxygen saturation simultaneously. We recorded the TOI and rSO2 during DHCA and compared whether NIRO and O3 changed similarly, because the value of TOI and rSO2 decreased dramatically in each DHCA typically.

Results: Twenty-nine patients were enrolled in this study. There were 144 times of DHCA in this study. We obtained bilateral cerebral oxygen saturation (CH1: left frontal side, CH2: right frontal side) at 288 points. The values of rSO2 were compared with TOI at pre-DHCA, DHCA, and the end of reperfusion. The values of rSO2 decreased during DHCA and improved in reperfusion phase in both devices. The time course of change of TOI and rSO2 was shown in Figure 1. Further %change of rSO2 and TOI were in Figure 2.

We used mixed linear regression model to examine the difference between NIRO and O3. There were significant interactions between the rSO2 and TOI value in DHCA (P<0.001) (Figure 1) Also, there was a significant interaction between the % change of rSO2 and TOI (P<0.001) (Figure 2).

F3FIGURE 1F4FIGURE 2

Conclusion: The values and the %changes of TOI and rSO2 were significantly different during DHCA. Both devices reflected the change in cerebral oxygen saturation in DHCA.

[SNACC-4] A Feasibility Study on Caffeine Citrate to Facilitate Intraoperative Brain Mapping and Cognitive Testing during Awake Craniotomies

Yang, J, Guo S. University of Washington, Bellevue, Washington, United States

Backgrounds: Awake craniotomy is usually performed when eloquent cortical tissue is located in close proximity to the resected area. The success of an awake craniotomy relies on a valid intraoperative brain mapping and cognitive test. In recent studies, intravenous caffeine was shown to be safe and accelerated emergence from isoflurane anesthesia. There are interests whether caffeine could facilitate intraoperative testing by accelerating emergence and preventing post-emergence drowsiness. To our best knowledge, the safety of intravenous caffeine administration during awake craniotomies was not examined.

Methods: We conducted a retrospective chart review on awake craniotomy patients receiving intravenous caffeine citrate during emergence before intraoperative brain mapping and cognitive testing during August 2021 and Feb 2022 in a tertiary care university hospital. Patients’ characteristics, baseline symptoms and neurological deficits, tumor characteristics, caffeine citrate dosage, pre- and post-mapping anesthetic formulation, infusion rates, airway management, duration of emergence (defined as from the end of surgical exploration to patient meaningfully following commands), intraoperative awake time (between following commands to resuming sedative infusion after testing), intra-testing sustained hemodynamic or behavioral perturbations (e.g., hypertension (systolic blood pressure >140 mmHg), tachycardia (heart rate >100 beats per minute), arrhythmia, anxiety, and agitation), brain mapping and cognitive testing issues (e.g., abnormal electrocorticography signals, prolonged drowsiness that prevented testing) were recorded.

Results: Five patients receiving awake craniotomy by 2 surgeons were included. They aged from 53 to 72 years old, were 80% female, and had BMI between 27.3 and 36.2. Before the brain mapping and cognitive testing, laryngeal mask airway was placed in 3 patients and 2 patients did not have any airway instrumentation except for nasal trumpets. Four patients received 15 mg/kg of caffeine citrate and one received 4 mg/kg. Dexmedetomidine (ranging from 0.2-0.7 mcg/kg/hr, following loading dose 1 mg/kg in 10 min), propofol (ranging from 15-125 mcg/kg/min, with intermittent bolus), remifentanil (0.02-0.15 mcg/kg/min), fentanyl were given pre-testing in 4, 5, 3, and 1 patient, respectively. Emergence time ranged from 4 to 8.5 minutes and intraoperative awake time ranged from 40 to 74 minutes. One patient reported subjective performance anxiety and presented with mild hypertension and tachycardia that required pharmacologic interventions. No arrhythmia, agitation, and brain mapping and cognitive testing issues were recorded.

Discussion: In our case series, intravenous caffeine citrate administration was safe and feasible during awake craniotomies. Its utility to accelerate emergence or facilitate intraoperative brain mapping and cognitive testing warrants further investigation.

[SNACC-5] A mannequin-based non-randomized cross over simulation study for emergency airway rescue during inadvertent accidental extubation in prone position

Rajaleelan W, Tuyishieme E, Dinsmore M, Unger Z, Venkataraghavan L. University of Toronto, Ottawa, Ontario, Canada

Introduction: Accidental extubation during prone position can be a life-threatening emergency requiring rapid establishment of airway. However there is limited evidence of the best airway rescue method for this potentially catastrophic emergency. Aim of the study was to determine the most effective method for airway rescue in case of an inadvertent extubation during prone positioning by comparing two techniques using three devices namely the supraglottic airway, video laryngoscope, and fiber optic bronchoscope.

Methods: This is a non-randomized cross-over mannequin quality study comparing the airway rescue performances of three techniques using two devices namely the supraglottic airway (IGEL), video laryngoscope (CMAC), and fiber optic bronchoscope(FOB). A Mayfield pin was placed on a mannequin in the OR, which was fixed to the OR table and the mannequin was fixed in the prone position. Anesthesia participants (fellows and staff) were instructed to insert a standard #4 LMA igel ,a ET with a CMAC and an ET with a fiberoptic bronchoscope in an order of their preference, into the mannequin in the standard surgical prone position. The participants were given the option of adjusting the height of the table prior to the airway intervention, however no other modifications to the mannequin position were permitted. Successful airway was confirmed by observation of bilateral inflation of mannequin lungs using an AMBU bag. Time (seconds) to successful airway was recorded.

Results: Twenty-three participants 11 (47.8%) Staff anesthesiologists and 12(52.1%) anesthesia fellows) were recruited for this study. Five (23.8%) participants (2 staff and 3 fellows) had a prior experience of handling an inadvertent prone extubation in their career. The mean experience of the participants in anesthesiology as a specialty was 11.939(5.76) years. All the participants were successful in establishing a supraglottic device as a temporary salvaging device.5 fellows (21.1%) and 2(8.6%) staff failed to establish a definitive ET tube using the CMAC and 1 (4.3%) fellow and 1 4.3%) staff failed to establish a definitive ET using the FOB before the allotted time of 180 secs therefore concluding it as a failed attempt.

The mean (SD) time taken to secure the airway using the LMA was 18.65(5.01) seconds amongst the fellows and 17.61 (4.67) sec amongst the staff. The mean time taken to secure the airway using the CMAC was 80.96(42.56) sec amongst the fellows and 95.19(28.45) sec amongst the staff. The mean time taken to secure the airway using the FOB was 67.55(29.06) sec amongst the fellows and 51.60(27.03) sec amongst the staff. There were significant differences in the time required for definitive airway management between the supraglottic airway and video laryngoscope [Mean (SD)=69.64 (36.32) 95% CI=53.94-85.35 t(22)=9.19, P<0.001] ,the video laryngoscope and fiber optic [Mean(SD)=27.84(44.12)95% CI=CI=8.76-46.93,t(22)=3.02,P=0.006)],the fiber optic and supraglottic airway[ (Mean(SD)=41.80sec (27.30),95%CI=29.99-53.60t(22)=7.43, P<0.001)].

Number of years of prior experience as a staff did not make a significant difference in time take to establish a definitive airway. Fellows, compared to staff were faster in establishing a definitive airway using a CMAC and slower using a FOB, but they failed more times than the staff anesthesiologists.

Conclusion: Accidental prone extubation can be an acute emergency. A LMA can be used as a temporary airway and the CMAC and FOB can be used to establish a definitive airway with an ET.Adequate training in prone intubation techniques should be part of the curriculum for training residents, fellows and staff during airway simulation education. In the case of accidental inadvertent extubation during prone position, the results of this simulation study suggest that the supraglottic airway is faster and has higher success rate in comparison to the FOB and the CMAC as a rescue airway device (Fig. 1).

F5FIGURE 1:

Participant attempting to secure the airway using CMAC.

[SNACC-6] Airway bleeding in the PACU: A cautionary tail involving Neuro-IR

Krause M, Filipovic M, Steinberg A, Newhouse B, LaBuzetta J, Srejic U, Fejleh A, Tran M, Pearn M, Lemkuil B. UCSD Medical Center, San Diego, California, United States

A 65-year-old female with asthma and COPD, who underwent workup for syncopal episodes and headaches, was diagnosed with a left para-ophthalmic aneurysm. Aspirin 325 mg and clopidogrel 75 mg were initiated five days prior to elective treatment by neuro-interventional radiology. During the procedure, the patient received 4000 units of heparin, and flow diversion was achieved with Pipeline stent (Medtronic, Dublin, Ireland) deployment. Emergence from anesthesia was notable for coughing secondary to reactive airway disease and transient hypertension with a systolic blood pressure of 200 mmHg. The patient was suctioned and extubated awake. Post-extubation, she was neurologically intact but complained of throat soreness during transport to the postoperative acute care unit. Thirty minutes after extubation, her nurse noted that the patient was coughing up small amounts of blood. Five minutes later, the airway pager was called for copious blood emanating from the patient’s mouth. An attempt to rapidly secure the airway occurred after preoxygenation with RSI and direct laryngoscopy. The glottic opening was not visualized due to profound hemorrhage despite continuous suctioning. The endotracheal tube was passed into an area where bubbles had been seen, followed by end-tidal CO2 confirmation. The oropharynx was packed, fluids and blood were administered, and heparin was reversed with protamine. A spot sign on CTA suggesting hemorrhage from a branch of the left ascending pharyngeal artery was confirmed in the neuro-interventional suite and embolized. Following embolization, the patient was taken to the operating room for incision and drainage of neck hematoma and oropharyngeal examination. The left tonsil, left pharyngeal wall, posterior pharyngeal wall, and soft palate were distorted and difficult to differentiate by an experienced ENT surgeon. However, bleeding had markedly improved, and the area was re-packed using hemostatic agents. A left soft palate laceration was noted, and diffuse swelling precluded visualization of the glottic opening. The anatomic swelling and distortion persisted, resulting in an elective tracheostomy four days later. The patient was decannulated and tolerated oral intake one week later.

The precise hemorrhagic etiology remains uncertain. Mechanical soft tissue injury may have occurred due to intubation or suctioning, although immediate oropharyngeal bleeding would have been expected. Based on conversations with the ENT surgeon, profound swelling and intramuscular hemorrhage would not be consistent with primary oral tissue injury. Alternately, the sore throat may point towards a spontaneous retropharyngeal hemorrhage due to coagulopathy, coughing, or hypertension. Subsequent oropharyngeal communication may have occurred during recovery due to coughing or suctioning. Previous case reports and timing of bleeding onset support this theory.

Regardless of etiology, this case highlights a rare, life-threatening perioperative complication of a neuro-interventional procedure. Flow diverting stents commonly used to secure intracranial aneurysms carry significant thrombotic risk. As such, dual antiplatelet therapy is required for at least three months. In addition to profound platelet inhibition, intraoperative heparinization is often needed. The combination of medications impairing coagulation may have contributed to the reported complication and severity. Although the role of mechanical soft tissue injury in our case is uncertain, caution to avoid soft tissue injury should be employed. Abnormal postoperative oropharyngeal pain, difficulty swallowing, or voice changes should raise one’s index of suspicion for retropharyngeal hemorrhage. Like other causes of acute neck hemorrhage, rapid airway management may be required, and extreme difficulty should be anticipated due to impaired visibility and rapid anatomic distortion.

[SNACC-7] Alternative Electrode Placement to Facilitate Abbreviated Frontal EEG Monitoring in Surgeries Involving the Head and Face

Chauhan V*, Chang B*, Cassim T*, Rajan S†, Graves M*, Garcia P*. Columba University Medical Center, New York, New York, United States*. UT Health Houston, McGovern Medical School, Houston, Texas, United States†

Introduction: Abbreviated frontal EEG monitoring using monitors approved for titration of anesthetic medications (e.g., BiS® and Sedline™) are often abandoned in neurosurgical cases because the surgical approach might involve scalp near the recommended locations for electrode placement. This can be a problem as perioperative EEG monitoring can be particularly useful in these surgeries in optimizing the anesthesia delivery and enhancing the recovery profile. Here we investigate both bilateral and unilateral alternative electrode positions of the Sedline™ (Masimo, Inc. Irvine, California) sensor that might be used for continuous perioperative EEG monitoring, during surgeries that involve the head and face.

Methods: Data for this sub-analysis were collected from participants enrolled in an IRB approved study (IRB: AAAT9632). Data were collected in participants receiving general anesthesia, pharmacologic sedation, and in the absence of analgosedative agents. In most cases, we were able to compare 5 alternate electrode positions in each patient. Spectral edge frequency (95%-ile, SEF95) and patient state index (PSI) were measured in 20 second epochs for approximately 5 minutes in each configuration (15 measurements per electrode configuration). The recommended electrode placement was used as the standard comparator except where otherwise notes. Statistics performed (t-test) with GraphPad™ Prism).

Results: Data collection remains ongoing, and here we present our preliminary analysis of pilot data. Both intra-subject and inter-subject analyses are planned. Figure 1 summarizes the data for one subject not receiving sedation. Only one alternate electrode configuration (malar electrodes) failed to demonstrate a significant change in average PSI as compared to the standard bifrontal upright configuration (P=0.397). The bifrontal inverse, semi-lateral, and lateral upright configuration resulted in significantly different average PSI (P<0.0001). The lateral inverse configuration also demonstrated a difference in PSI (P=0.0036). Unilateral lead placement did not result in a statistically significant difference in asymmetry (absolute value of SEF95L- SEF95R, P=0.7916, unilateral vs bilateral). The semi-lateral position was excluded from the asymmetry analysis as it is not symmetric bilaterally. We also observed that inferior placement of frontal electrodes results in a decrease of SEF95).

F6FIGURE 1:

Sedline Placements Showing Different Spectograms and Abbreviated EEG Variables’ Values.

Conclusion: Our preliminary results suggest that alternate electrode configurations are achievable and may help guide the delivery of anesthetic agents, especially for providers comfortable with interpretation of quantitative EEG and analysis of the raw time-series EEG waveform. Although most alternate configurations resulted in a change of PSI, in general the magnitude of this change might be considered clinically insignificant. Caution should be exhibited with interpretation of EEG when the leads are placed inferiorly as attenuation of higher frequency activity may result in impairments in recognizing the “beta buzz” typically indicative of cortical activation.

[SNACC-8] An audit on Post Craniotomy Pain Management in a Tertiary University Hospital: A Quality Improvement Initiative

Wan Zakaria W, Tan W. University Malaya, Wilayah Persekutuan, Kuala Lumpur, Malaysia

Management of post craniotomy pain is challenging, especially to find the balance between providing adequate but also to avoid excessive analgesia that could mask new onset neurological deficits. Poorly managed post-operative pain will lead to many complications which result in overall delayed recovery, prolonging hospital stay and ultimately, an increase in healthcare costs.

Aim: To evaluate the management of post craniotomy pain management at a single tertiary university hospital in Kuala Lumpur, Malaysia.

Methods: A retrospective analysis on all patients above 18 years old who underwent elective craniotomy between June 2021 to December 2021. Patient demographics, site of craniotomy, pre and post-operative pain scores and analgesics, number of ICU days, and any post-operative cardiovascular, renal, respiratory or gastrointestinal complications in the first 72 hours following craniotomy, were collected from patients electronic medical records.

Results: A total of 36 patients were recruited with 28 patients who had supratentorial versus 8 patients who had infratentorial craniotomy. More female patients were in the supratentorial group however, other patient demographics such as age, weight, height and BMI were comparable. Most of the patients recruited were ASA-PS Class II.

Most of the patients received general anaesthesia (GA) with Sevoflurane while only one patient in the supratentorial group received total intravenous anaesthesia (TIVA). Intraoperatively, all patients received intravenous Remifentanil and paracetamol. Skin infiltration at surgical site was performed in all but one patient who received regional scalp block. The most striking differences were patients in the infratentorial group received a higher Remifentanil target effect site (more than 4 ng/mL) and also higher doses of intravenous Morphine within 72 hours perioperatively (mean 5.5 mg vs 3 mg).

Post-operative pain scores were higher in the infratentorial group in post-operative Day 1, and most of the supratentorial group of patients reported mild pain and remained pain free in the subsequent days (P value 0.003). All patients continued to receive intravenous paracetamol and intravenous parecoxib was added after 24 hours. Higher percentage of patients in the infratentorial group (50% vs 28.5%) requires intravenous morphine during the post-operative period.

As expected, a higher percentage of patients who had infratentorial craniotomy required longer ICU stay (50% vs 10%). Transient neurological deficits were seen in 2 out of 8 patients (25%) in the infratentorial group compared to 3 patients (10%) in the supratentorial group. A total of 2 patients from the supratentorial group developed ECG changes, and 1 was unable to tolerate orally. However all complications were resolved by Day 3 post-operatively. There were no mortalities recorded.

Conclusion: Based on this audit, majority of the elective post-craniotomy patients experienced manageable pain with very few complications, however a larger sample size is desirable to represent the target population. From this small study we can conclude that although we are practising a multi-modal analgesia approach, a standardised pain management protocol will be beneficial. This will be a part of the unit’s Quality Improvement initiative towards implementing an Enhanced Recovery In Neurosurgery protocol, locally.

[SNACC-9] Anaesthetic management and outcomes of patients undergoing embolization of brain Arterio venous malformations by “Pressure cooker technique”: Retrospective case series study

Srinivasaiah R, Kumar V, Chandran A, Puthuran M. The Walton Centre, Liverpool, United Kingdom

Introduction: The treatment of brain arteriovenous malformations (AVM) represents a therapeutic challenge, regardless of chosen modality of treatment. Traditionally endovascular embolization of Intracranial AVM’s has been used as preparation of patients for surgical resection or radio-surgery. However, the new technique employed in the Trans-venous embolization of brain AVMs also known as “Pressure cooker technique” (1) can be used as sole treatment method to cure the AVM’s. This new technique often necessitates some means of arterial inflow control to prevent reflux of embolic agent and to aid retrograde penetration of the liquid embolic agent from venous to the arterial side(nidus). Anaesthesiologists play an important role in reducing the blood flow through AVM to cause flow arrest during embolization by various techniques. We share our experience of managing Embolization of Intracranial AVM’s under hypotensive anaesthesia.

Methods: All AVM patients treated via trans-venous embolization over 2 years period between December 2017 to November 2019 were included in this study. We collected the data on patient demographics, grade & location of AVM’s, ASA grade, anaesthetic technique, hypotensive agents used, duration of hypotension, peri procedure complications, post procedure angiogram at 3 months to look at AVM occlusion and outcome at 1 year measured by modified Rankin score (MRS).

Results: We treated 10 patients during this period with trans-venous embolization of Intracranial AVM’s of which 7 patients were Male and 3 were females. The mean age of these patients was 38 years (range 20-61 y), 7 of these patients had higher Spetzler-Martin AVM grade of 3 or more and AVM was in deep location like quadrigeminal plate, basal ganglia, cerebellum. All the patients received General anaesthesia with inhalation technique, Labetalol was the most commonly used drug for maintenance of hypotensive anaesthesia. Duration of hypotension ranged between 26 minutes to 180 minutes depending on the complexity of AVM’s. Degree of hypotension depended on patient comorbidities and varied between MAP of 50-70 mm hg. One patient had Intracranial haemorrhage requiring craniotomy and evacuation of clot. The angiograms performed at 3 months showed complete occlusion of AVM’s in 9 patients and one patient had 90% occlusion. All the 10 patients were alive at 1 year and 9 patients had a favourable outcome of MRS 0-2 and 1 patient had outcome of MRS 3.

Discussion: Various techniques have been employed to achieve reduced blood flow through AVMs. Intravenous Adenosine has been used to cause transient asystole and flow arrest, however it cannot be used in all patients and is associated with haemodynamic complications. Rapid ventricular pacing (2) has also been used to achieve the flow arrest however the evidence of this in interventional neuroradiology is limited. Selective temporary flow arrest during embolization can also be achieved by placement of intraarterial balloons to reduce intra-nidal pressure and flow (3). In our centre we performed arterial embolization of AVM’s and insertion of flow coils to reduce the blood flow through AVM nidus followed by venous embolization with Onyx/Squid under hypotensive anaesthesia with a MAP of 50-70 mmhg. We also employed cessation of ventilation for up to a minute at the time of trans venous injection of Onyx. Both these simple measures prevented the movement of Onyx and helped in obliterating the AVM without resorting to complex techniques which has an effect on haemodynamics.

To conclude Trans-venous embolization can be safely used as curative technique in the treatment of intracranial AVM’s as it has shown to be safe, effective and curative in 90% of the patients. Hypotensive technique can be successfully used in the management of curative trans-venous embolization of AVM’s to hold the glue at the venous end of AVM (Fig. 1 and 2).

F7FIGURE 1:

AVM before embolization.

F8FIGURE 2:

After trans-venous embolization.

[SNACC-10] Anesthetic Considerations for Chiari I Malformation in a BMI 62 Patient

Patel D*, Palmeri N*, Yeh C*, Hussain H†. University of Illinois College of Medicine, Chicago, Illinois, United States*. Rosalind Franklin University, Chicago, Illinois, United States†

Patients with Chiari I malformations present with tonsillar herniation below the foramen magnum causing abnormal spinal anatomy. Anesthesia challenges in this population include difficult airway management, monitoring intraoperative autonomic dysfunction, avoiding increased intracranial pressure, and accommodating sensitivity to neuromuscular blockade. We present a case with an additional airway management challenge due to morbid obesity with a BMI of 62. A 23 year old female with a history of Covid pneumonia and morbid obesity who presented with syringomyelia and Chiari I malformation. She initially presented with bilateral numbness, tingling, weakness, and pain in her hands. Imaging with MRI at the time showed downward displacement of the cerebellar tonsils with the tips reaching the lower portion of C1 and overall 10-12 mm displacement below the level of the foramen magnum. Syrinx was also visualized from the level of C1-C2 extending down to the level of T5-T6. Repeat MRI a year later showed no significant changes. However, she has worsening symptoms of pain in her right arm preventing her from working. She is agreeable to surgical decompression of the posterior fossa through a suboccipital craniotomy with resection of the posterior arch of C1 with duraplasty. Significant findings on the physical exam include Mallampati III, shorter thyromental distance, and limited range of motion of her cervical spine due to pain in her arms. We chose awake fiberoptic intubation due to difficult airway from morbid obesity and limited cervical spine range of motion and the consideration of hypercapnia induced from brief apnea the patient may not tolerate. She was premedicated with versed, glycopyrrolate, and dexmedetomidine, and given a 5% lidocaine paste “lollipop” to topicalize oropharynx. She was also started on a low dose remifentanil infusion for sedation during the awake fiberoptic approach. Blood pressure, heart rate, respiratory rate with continuous end-tidal capnography, and pulse oximetry were monitored during the awake fiberoptic intubation. A 7.0 endotracheal tube was lubricated with viscous lidocaine and placed over a fiberoptic scope. Once there was visualization of the vocal cords, additional 2% lidocaine was administered directly at the vocal cords. She was intubated smoothly on the first attempt. She was then immediately induced to general anesthesia with propofol and non-depolarizing muscle relaxant to avoid using succinylcholine due to the possible hypersensitivity caused by denervation. Intraoperatively, a conventional air warmer was used to prevent hypothermia. Invasive arterial blood pressure monitoring was applied. Normotensive blood pressure and normocapnia were maintained throughout the surgery. Muscular blockade was reversed with sugammadex at the end of surgery to ensure adequate ventilation especially with the patient’s body habitus. Upon extubation, the patient had acute hypertension which was managed by nicardipine infusion and hydralazine boluses. Patient was taken to a neurosurgical intensive unit and monitored for two days. She was discharged home without any complication.

In conclusion, anesthetic considerations for patients with Chiari I malformation include airway management, monitoring for autonomic dysfunction, avoiding increase in ICP, and optimizing postoperative neurological status with balanced anesthetic management.

[SNACC-11] Anesthetic management for intradural clip ligation and reconstruction of recurrent previously coil - embolized complex anterior communicating artery aneurysm: A Case Report

Elser A, Chakraborty I, Day J, Gupta P. University of Arkansas for Medical Sciences College of Medicine, Little Rock, Arkansas, United States

We present a 33-year-old male patient with a history of ruptured anterior communicating artery cerebral aneurysm, which was then coil embolized in 2016. In March 2022 he was found to have a large recurrence of this aneurysm at the coiling site from a dominant left anterior cerebral artery with a new superiorly projected aneurysm measuring 4.7×3.6 millimeters and an inferior portion measuring 5.9×4.8 millimeters. This time, a left orbitocranial skull base approach was performed for intradural clip ligation and reconstruction of the recurrent aneurysm.

A combined inhalational and intravenous general anesthetic was administered. Neuro-monitoring was performed with somatosensory evoked potentials, motor evoked potentials, and electroencephalogram for the entirety of the case. After the dura was exposed and burst suppression was achieved, the area was dissected to reveal the previously coiled aneurysm and corresponding vessels required for clipping. Temporary clips were placed, and the previously embolized portion of the aneurysm was excised. However, there was initial difficulty optimizing vessel flow while also obtaining optimal clip placement. This process of optimization was complicated by intraoperative aneurysm rupture, which was efficiently controlled. Temporary hypotension was achieved with small boluses of intravenous nitroglycerine which created a bloodless field for the surgeon to clip the aneurysm rupture. During clip manipulation, decreased amplitude of motor evoked potentials in the right lower extremity were noted without any change in the somatosensory evoked potentials. After the clips had been repositioned in their final location, motor evoked potentials slowly recovered to their pre-clipping baseline. The remainder of surgery and emergence from general anesthesia were uneventful. Postoperatively, the patient exhibited right-sided hemiparesis and mild dysarthria, both of which improved within 48 hours and prior to patient’s discharge from the hospital (Fig. 1).

F9FIGURE 1:

Excision of previously embolized cerebral aneurysm in progress.

[SNACC-12] Anesthetic Management of Patients with Hypothalamic Hamartoma-A Retrospective Study

Seshan J, Rath G, Bindra A, Chandra P, Doddamani R. Department of Neuroanaesthesiology & Critical care, AIIMS, New Delhi, Delhi, India

Introduction: Hypothalamic hamartoma (HH), with an incidence of 1:200,000 children, is a recognized cause of drug refractory epilepsy (DRE) and endocrine abnormalities. Surgery for DRE has become increasingly popular with the advent of modern minimally invasive techniques aimed at reducing the morbidity. Possible anesthetic concerns in HH includes that of pediatric age group, interaction with anti-epileptic drugs (AED), and endocrinopathies.

Materials: After institute ethics committee approval, a review of perioperative medical records and anesthetic charts of patients who underwent surgery for HH over a period of 5 years (2016-2020) was done. Preoperative data including demographics, neurological status, AED therapy, and endocrine status was collected. Surgical method, anesthetic technique, blood loss, fluid administered and details of any intraoperative adverse event were sought. Details of postoperative ventilation, if any, duration of ICU and hospital stay, and postoperative complications were also recorded.

Results: Eighteen patients diagnosed with HH (15 children and 3 adults) underwent 24 procedures [Stereotactic radiofrequency ablation in 21 (87%) and craniotomy for excision/disconnection in 3 (13%)]. Median age was 6 years (IQR 3,8). All patients were treated for DRE with atleast 3 AEDs, Levetiracetam 11 (61%) and Clobazam 9 (50%) being the most common. Precocious puberty was the major endocrinological manifestation in 7 (39%) patients. Airway abnormalities included obstructive sleep apnea and bifid epiglottis in 1 patient each. Balanced anesthesia with Fentanyl, Sevoflurane and Rocuronium was used in all patients. Intraoperative events noted were tense brain and suspected venous air embolism in 1 patient each. Seven (29%) patients were ventilated postoperatively due to inadequate awakening or surgical handling. Postoperative complications included dyselectrolytemia [3 (12%)], respiratory events [2 (8%)], hypothyroidism in 5 (27%) and hypocortisolism 2 (11%). Duration of ICU stay was 2 days (IQR 1,5).

Conclusions: Anesthesia for minimally invasive approach to DRE is safe. Possibility of AED interaction and surgical site edema should be considered in delayed awakening from anesthesia. Endocrinopathy causing dyselectrolytemia should be promptly managed.

[SNACC-13] Anisocoria After Craniotomy

Churchill T, Knutson A, Hemmer L. Northwestern, Chicago, Illinois, United States

Introduction: Many complications of craniotomies can be identified by physical examination soon upon emergence from anesthesia. A neurologic exam is often performed to identify new onset weakness or cranial nerve abnormalities. In the case of a dilated pupil (anisocoria) after craniotomy there are several possible explanations, but the immediate concern is for increased intracranial pressure (ICP) and brain herniation. Dilation of the pupils is governed by the balance of sympathetic stimulation versus parasympathetic inhibition, so effects on either of these pathways must be considered1. Given the external position of the parasympathetic fibers in the third cranial nerve, they are especially susceptible to external compression in the cranial vault in the case of increased ICP2. As a result, most reasons for post-surgical unilateral pupil dilation are ominous and require prompt evaluation. However, when imaging is negative for etiologies of an acute increase in ICP (e.g. hemorrhage), other etiologies of perioperative anisocoria must be considered. Case: A 33 yo male with a history of refractory bilateral temporal lobe epilepsy, bipolar disorder, and iron deficiency anemia presented for bilateral stereotactic electroencephalogram (EEG) explantation. He underwent a routine standard general anesthetic with endotracheal intubation and muscle relaxation in supine position. Sevofluorane was used for anesthesia maintenance and a remifentanil infusion was used at the end of the procedure to facilitate a smooth emergence. For additional post-op pain control 20 milliliters of lidocaine 1% with epinephrine 1:100,00 was injected by the surgical team via a non-targeted scalp block above the eyebrows bilaterally. The scalp block occurred approximately ten minutes prior to emergence from anesthesia. The case lasted approximately one hour with no significant blood loss noted. Routine pupillary inspection by the anesthesiology team during anesthesia emergence identified right-sided unilateral pupil dilation. The neurosurgical team was immediately notified, and an emergency head CT was completed. The CT was unremarkable without hemorrhage or intracranial herniation.

Discussion: The cause of this patient’s anisocoria is still unknown, but the differential of unilateral pupil dilation after craniotomy is important to delineate. A review of the anatomy and physiology of the pupillary reflex can yield possible explanations. The physical dilation of the pupil occurs from the iris sphincter and dilator muscles which are governed by autonomic innervation through the ciliary nerves which pass through the retrobulbar space on their way to the eye from the cervical ganglion and back through Cranial Nerve III to the brainstem. Pharmacologic interference in the autonomic pathway (e.g. local anesthetic, epinephrine, scopolamine patch), physical interruption of the nerve signaling of Cranial Nerve III (hemorrhage, edema/inflammation, herniation), and pathologic central neurologic function (seizure activity) should all be considered when assessing a patient’s anisocoria in the perioperative period.

[SNACC-14] Assessment of impaired cerebral autoregulation by THRR using TCD and its correlation with neurologic outcome in patients with aSAH: A Prospective Observational Study

Panda N*, Katariya K†, Luthra A*, Mahajan S*. PGIMER Chandigarh, Chandigarh, India*. Tata Memorial Hospital, Mumbai, India†

Background: Cerebral Autoregulation (CA) is crucial in cases of neurological insult to the brain. It can be assessed by measuring Transient Hyperemic Response Ratio (THRR) using Transcranial Doppler (TCD). We aimed at assessing the incidence of impaired CA and its correlation with the neurological outcome in patients with aSAH

Methods: A prospective, observational study was conducted in 100 consecutive patients with aSAH who were planned for surgical clipping of aneurysm. THRR measurement using TCD was done for assessment of CA in preoperative and for 5 consecutive postoperative days. Neurological outcome was assessed using Glasgow Outcome Scale Extended score at discharge and 3, 6 & 12 months after discharge and its association with impaired CA was analysed.

Results: Impaired CA (THRR <1.09) was observed in 69 patients pre-operatively, 74 patients on the 1st and 2nd post-operative day, 76 patients on 3rd post-operative day and 78 patients on 4th and 5th postoperative day. Out of 78 patients who had impaired CA, 53.8% at discharge, 76.9% at 1 month, 69.2% at 3 month and 70.5% at 12 months had unfavourable neurological outcome significantly more than those with preserved CA.

Conclusion: Incidence of impaired autoregulation with ruptured cerebral aneurysm varies from 69-78% in the perioperative period as assessed by THRR. The deranged autoregulation is associated with significantly poor neurological outcome. Therefore, assessment of cerebral autoregulation using TCD-based THRR provides a simple, non-invasive bedside approach for predicting neurological outcome in aSAH.

[SNACC-15] Audit of Anaesthetic management and perioperative outcomes of children undergoing brain tumour resection surgeries in a tertiary cancer centre

Desai M. Tata Memorial Hospital, Mumbai, India

Background: Brain neoplasms in children represent 15% to 20% of all tumours in paediatric oncology. children undergoing neurosurgery present unique challenges for the anaesthesiologist. The aim of our study was to audit anaesthetic management and perioperative outcomes in children between the ages between 0-15 years, undergoing tumour resection surgeries procedures in our tertiary cancer institute over 5 years.

Aims and Objective: To audit: Intraoperative anaesthesia management :Adverse events during anaesthesia induction,Intraoperative neuromonitoring practices,Hypothermia/ Hyperthermia,A dverse events related to positions To study intraoperative complications:Hemodynamic instability - hypotension, hypertension, desaturation, tachycardia, bradycardia, arrhythmias, air embolism Blood loss, Intravenous fluid administration, Need of blood and blood products transfusion To study postoperative complications and outcomes: Post-operative elective ventilation, ,Reintubation within 24 hours after extubation, Duration of ICU (Intensive Care Unit) stay Readmission to ICU within 48 hours of discharge from ICU, Re-explorations, Electrolyte disturbances.

Method: After approval from Institutional ethical committee, retrospective analysis of prospectively collected Data was performed. Data was collected from Electronic Medical records, patient files, intraoperative anaesthesia and postoperative ICU charts.

Results: Out of 171 tumour resection surgeries, 79(46%) were supratentorial tumours, and 92( 54% ) infratentorial tumours. 43.8% children had Glial, 38% Embryonal 8% sellar ,10.2% other tumour histopathology.

Median age was 6 years and the median duration of surgery was 300 minutes. 21.63% tumour excisions were performed under Intraoperative neuromonitoring using TIVA. 26/171 (15.2%) children had massive blood loss. Mean blood loss for embryonal tumours (25.14±22.02 mL/kg), sellar and pineal tumours (14.02±13.78 mL/kg), neural cell and mixed neural glial tumours(11.28±6.53 mL/kg). Perioperative respiratory adverse events (PRAE) and intraoperative critical events were reported none. Only one child in our study needed vasoactive drug infusion intraoperatively and postoperatively. There was no event of air embolism. Median postoperative ICU stay (including for those with the massive blood loss) was 2 days. Postoperative 48 hours Mortality was1%, and 28 days mortality was 4%. On univariate analysis, new found no correlation of any one of the parameters (emergeny or elective, duration of surgery and anaesthesia, WHO histopathologic grade of tumour, blood loss, and preoperative GCS) with postoperative complications.

Conclusion: Anaesthesia practices and management for paediatric neurosurgical procedures are safe in our institute as the intraoperative complications are minimal and less than what is documented in literature. (28 days mortality for tumour resection surgeries is comparable with other small studies in literature but higher from studies reported from high volume speciality centres) (Table 1).

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