Search

A healthy 26-year-old man with cerebral arteriovenous malformation underwent staged endovascular embolization with Onyx followed by awake craniotomy for resection. The perioperative course was complicated by tachycardia and severe intraoperative hypoxemia requiring significant oxygen supplementation. Postoperative chest computed tomography (CT) revealed hyperattenuating Onyx embolization material within the pulmonary vasculature, and an electrocardiogram indicated possible right heart strain, supporting clinically significant embolism. With awake arteriovenous malformation resection following adjunctive Onyx embolization becoming increasingly employed for lesions involving the eloquent cortex, anesthesiologists need to be aware of pulmonary migration of Onyx material as a potential contributor to significant perioperative hypoxemia.

A 65-year-old man undergoing posterior cervical decompression and fusion demonstrated absent lower extremity evoked potential (EP) after prone positioning and before incision. Localized EP change pointed to either a technical or positional culprit. After excluding technical causes, we performed a wake-up test to rule out positioning as the culprit. During the test, we observed both symmetrical and asymmetrical hemispheric changes in density spectral array β and γ bands that correlated with awakening, eye-opening, and extremity movements. By providing real-time information on brain state, processed electroencephalogram (EEG) can facilitate a safe wake-up test by showing high-power β and γ activities that precede awakening.

Background: Surgery for posterior spine instrumentation often requires major transfusion. The aim of this study was to develop and test the validity of a model for predicting intraoperative major transfusion (>4 U total red blood cells), based on preoperative patient and surgical variables, that was applicable to adult patients undergoing cervical, thoracic, and/or lumbar spine deformity surgery with and without osteotomies. Materials and Methods: The perioperative data from 548 patients who underwent ≥3 levels of posterior spinal fusion with instrumentation between January 1, 2003 and May 30, 2009, were retrospectively collected to create a model for predicting major blood transfusion. The validity of the model was retrospectively tested with a separate data set of 95 patients who underwent surgery from June 1, 2009 through September 30, 2010. Results: There was a 59.5% incidence of major transfusion in the derivation set of patients. Independent predictors of major transfusion were operation duration, number of posterior levels instrumented, surgical complexity score, and preincision hemoglobin. This model was able to predict major transfusion significantly better than a previously published model (ROCAUC=0.89; 99% confidence interval, 0.80-0.90; P Conclusions: Our model has an increased accuracy for predicting the probability of major transfusion compared with a previously published model. In addition, our model is applicable to all types of spine fusion surgery and accounts for the complexity of surgical instrumentation, the number of levels instrumented, and the predicted duration of surgery as independent variables.

Arteriovenous malformations (AVMs) of the brain are very complex and intriguing pathologies. Since their initial description by Luschka and Virchow in the middle of the 19th century, multiple advances and innovations have revolutionized their management and surgical treatment. Here, we review the historical landmarks in the surgical treatment of AVMs and then illustrate the most recent and futuristic technologies aiming to improve outcomes in AVM surgeries. In particular, we examine potential advances in patient selection, imaging, surgical technique, neuroanesthesia, and postoperative neuro-rehabilitation and quantitative assessments. Finally, we illustrate how concurrent advances in radiosurgery and endovascular techniques might present new opportunities to treat AVMs more safely from a surgical perspective.

When temporary arterial occlusion of the parent artery is difficult for anatomical reasons, or when inadvertent aneurysmal rupture occurs during surgical dissection, adenosine administration can be used to produce flow arrest and brief, profound systemic hypotension that can facilitate intracranial aneurysm clip ligation. There is a concern, however, that the flow arrest and profound hypotension produced by adenosine, although brief, may cause cerebral ischemia and therefore worsen neurologic outcome compared with other techniques to facilitate aneurysm clip ligation. Therefore, we performed a retrospective, case-control study to determine whether adenosine-induced flow arrest had negative effects on the neurologic outcome of our patients.We reviewed the perioperative records of all patients in our intracranial aneurysm surgery outcomes database between August 1, 2006, and June 15, 2012. The primary outcome was the presence or absence of a poor neurologic outcome 48 hours after surgery, with a modified Rankin scale score2 being defined as a poor neurologic outcome. The neurologic outcome at the time of hospital discharge was a secondary outcome. Secondary outcomes related to cardiac morbidity included atrial or ventricular arrhythmia requiring treatment and elevated cardiac biomarkers consistent with ischemia (i.e., Troponin-I).During the study period, adenosine-induced flow arrest was used in 72 of the 413 patients (17.4%) who underwent intracranial aneurysm clip ligation. The difference in the incidence of poor neurological outcome, with or without the use of adenosine, was no larger than 15.7% at 48 hours after surgery (P =0.524) or -12.7% at discharge (P = 0.741). In addition, the difference in the incidence of cardiac morbidity was no larger than -16.0% for persistent arrhythmia (P = 0.155) or -9.4% for biomarkers of myocardial ischemia (P = 0.898) in the initial 48 hours after surgery.When used to facilitate intracranial aneurysm clip ligation, adenosine-induced flow arrest was associated with no more than a 15.7% increase or a 12.7% decrease in the incidence of a poor neurologic outcome at either 48 hours or at the time of hospital discharge. In addition, adenosine use was not associated with cardiac morbidity in the perioperative period (i.e., persistent arrhythmia or biomarkers of cardiac ischemia).

Anemia is common in patients with aneurysmal subarachnoid hemorrhage (SAH), but these patients have constituted only a small fraction of those studied in large trials of anemia and transfusion. Unlike other critically ill patients, those with SAH face a well-defined risk of vasospasm and cerebral ischemia in the weeks after their hemorrhage. The risk of ongoing ischemia may make them less able to tolerate anemia and more likely to benefit from blood transfusion. The available data show that anemia is associated with poor outcomes after SAH but that blood transfusion does not consistently improve physiological markers, and it may be associated with poor outcomes. Most of these data are observational in nature, although 1 recent study demonstrated the safety and feasibility of maintaining relatively high transfusion thresholds in patients with SAH. Larger, randomized trials are needed to determine at what levels of anemia patients with SAH might benefit from transfusion, the optimal timing of transfusion, and how to identify those patients who are most likely to benefit.

Standardization and accreditation of fellowship training have been considered in the field of neuroanesthesiology. A prior survey of members of the Society for Neuroscience in Anesthesiology and Critical Care (SNACC) suggested strong support for accreditation and standardization. In response, SNACC created a Task Force that developed curricular guidelines for neuroanesthesiology fellowship training programs. These guidelines represent a first step toward standards for neuroanesthesiology training and will be useful if accreditation is pursued in the future.

BACKGROUND Mannitol is often used during intracranial surgery to improve surgical exposure. Furosemide is often added to mannitol to augment this effect. The concern exists, however, that the augmented diuresis caused by the addition of furosemide to mannitol may cause hypovolemia and hypoperfusion, hypokalemia, and hyponatremia. We examined the intraoperative safety of low-dose furosemide (0.3 mg/kg) combined with mannitol (1 g/kg). METHODS We observed 23 patients in a double-blind, block randomized, placebo-controlled study to examine the effects of furosemide (0.3 mg/kg) when combined with mannitol (1 g/kg) on surgical brain relaxation for tumor surgery. Mannitol and the study drug (furosemide or placebo) were administered, and arterial blood gases with electrolytes (sodium, potassium, and lactic acid) and urine output volume were recorded every 30 minutes for 3 hours. Plasma sodium, potassium, and lactic acid concentrations, and interval urine outputs, were compared across time and between furosemide-placebo assignment groupings, with a P

BACKGROUND Clip application for temporary occlusion is not always practical or feasible. Adenosine is an alternative that provides brief periods of flow arrest that can be used to advantage in aneurysm surgery, but little has been published on its utility for this indication. OBJECTIVE To report our 2-year consecutive experience with 40 aneurysms in 40 patients for whom we used adenosine to achieve temporary arterial occlusion during aneurysm surgery. METHODS We retrospectively reviewed our clinical database between May 2007 and December 2009. All patients who underwent microsurgical clipping of intracranial aneurysms under adenosine-induced asystole were included. Aneurysm characteristics, reasons for adenosine use, postoperative angiographic and clinical outcome, cardiac complications, and long-term neurological follow-up with the modified Rankin Scale were noted. RESULTS Adenosine was used for 40 aneurysms (10 ruptured, 30 unruptured). The most common indications for adenosine were aneurysm softening in 17 cases and paraclinoid location in 14 cases, followed by broad neck in 12 cases and intraoperative rupture in 6 cases. Troponins were elevated postoperatively in 2 patients. Echocardiography did not show acute changes in either. Clinically insignificant cardiac arrhythmias were noted in 5 patients. Thirty-six patients were available for follow-up. Mean follow-up was 12.8 months. The modified Rankin Scale score was 0 for 29 patients at the time of the last follow-up. Four patients had an modified Rankin Scale score of 1, and scores of 2 and 3 were found in 2 and 1 patients, respectively. CONCLUSION Adenosine appears to allow safe flow arrest during intracranial aneurysm surgery. This can enhance the feasibility and safety of clipping in select circumstances.

Somatosensory evoked potentials (SEPs) were monitored during 113 operations for the clipping of 134 cerebral aneurysms. Changes in peak latency and amplitude of early cortical SEP as well as central conduction time were evaluated. In 58 cases surgical occlusion of arterial vessels or other events occurred, and in 17 of these cases such events were associated with SEP changes or loss. Arterial occlusions resulted from temporary clipping of a feeding blood vessel (22), accidental clipping of a vessel (12). and intentional permanent vessel occlusion (8). A total SEP loss was seen in 2 cases of accidental vessel occlusion and in 6 cases of temporary vessel clipping. Significant SEP changes were found in 6 patients with temporary clipping, and once each with retraction of the cerebellum, retraction of the middle cerebral artery, and after intentional permanent vessel occlusion. Response to these changes included reapplication of aneurysm clips, repositioning of retractors, or removal of temporary clips. Stable SEP signals during 13 cases allowed the surgeon to proceed with the surgical course. Despite the limitations of SEP monitoring in certain anatomical locations, it has been found to be helpful in the operative management of some cases such as multilobed aneurysms of the middle cerebral artery, giant aneurysms, trapping procedures, and procedures requiring temporary vessel occlusion. (Neurosurgery 26:61-70, 1990)