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An awake craniotomy for tumour and epilepsy surgery allows for the mapping of eloquent brain function to minimize its injury and/or for the localization of an epileptic focus. The insertion of deep brain stimulators for the treatment of functional neurosurgical disorders is also frequently performed with an awake patient. The role of the anaesthetist is important in order to have a comfortable and cooperative patient, for the use of appropriate sedation to allow for mapping, and careful vigilance to rapidly diagnose and treat any complication. This chapter discusses the overall rationale for, and the anaesthetic management of, patients undergoing awake craniotomy for tumours, epilepsy surgery, or deep brain stimulator placement.

Background Awake craniotomy (AC) is performed for the resection of brain tumours in close proximity to areas of eloquent brain function to maximize reduction of tumour mass and minimize neurological injury. This study compares the efficacy and safety of dexmedetomidine vs propofol-remifentanil-based conscious sedation, during AC for supratentorial tumour resection. Methods Prospective, randomized, controlled trial including 50 adult patients undergoing AC who were randomly assigned to a dexmedetomidine (DEX group, n+25) or propofol-remifentanil group (P-R group, n+25). The primary outcome was the ability to perform intraoperative brain mapping assessed on a numeric rating scale (NRS). Secondary outcome was the efficacy of sedation measured by the modified Observer's Assessment of Alertness/Sedation (OAA/S) scale. Other outcome measures including haemodynamic and respiratory variables, pain, sedation and anxiety scores, adverse events, and patient satisfaction were also compared. Results There were no differences between DEX and P-R groups regarding the ability to perform intraoperative brain mapping [mean NRS score (95% CI): 10.0 (9.9–10.0) vs 9.7 (9.5–10.0), P+0.13] and level of sedation during mapping [mean OAA/S score (95% CI): 4.1 (3.5–4.7) vs 4.3 (3.9–4.7), P+0.51], respectively. Respiratory adverse events were more frequent in the P-R group (20 vs 0%, P+0.021). Heart rate was significantly lower in the DEX group across time (P Conclusions Quality of intraoperative brain mapping and efficacy of sedation with dexmedetomidine were similar to propofol-remifentanil during AC for supratentorial tumour resection. Dexmedetomidine was associated with fewer respiratory adverse events. Clinical trial registration NCT01545297.

Pre-surgical embolization of vascular brain and spinal tumours is an effective method of reducing intraoperative bleeding. Many technological developments of the microcatheters and embolic materials that are used have led to better outcomes in tumour embolization. Pre-operative embolization has become a standard of practice in the management of many vascular brain and spinal tumours. Anaesthesiologists are generally involved with these procedures which may be performed with general anaesthesia, conscious sedation or monitored anaesthesia care. The choice of the anaesthetic technique usually depends on the patient characteristics, tumour location, vascularity of the tumour and most importantly the neuroradiologist and/or institutional preferences. There is limited information in the literature on the anaesthetic considerations for these patients. The aim of this review is to provide a brief overview of the indications, techniques, complications and relevant anaesthetic considerations for patients undergoing pre-surgical embolization of intracranial and spinal tumours.

Seizures are common with 5%–10% of the general population experiencing a seizure in their lifetime and 1%–3% having a seizure disorder. Patients undergoing neurosurgical procedures are at an increased risk of perioperative seizures, including seizures occurring during surgery. To prevent and minimize perioperative seizures, the preoperative optimization of patients with seizures is crucial, including administration of regular antiepileptic agents. Status epilepticus is a true neurological emergency, with early and aggressive treatment being imperative for successful management. This chapter reviews the diagnosis, risk factors for seizures, and the initial treatment of an acute perioperative seizure as well as the management of status epilepticus.

Epilepsy surgery is a well-established therapeutic intervention for patients with medically refractory seizures. Success of epilepsy surgery depends on the accurate localization and complete removal of the epileptogenic zone. Despite the advances in presurgical localization modalities, electrocorticography is still used in approximately 60% to 70% of the epilepsy centers in North America to guide surgical resection of the epileptogenic lesion and to assess for completeness of surgery. In this review, we discuss the principles and intraoperative use of electrocorticography, the effect of anesthetic drugs on electrocorticography, and the use of pharmacoactivation for intraoperative localization of epileptogenic zone.

Patients with medically refractory epilepsy when referred for surgical treatment often undergo extensive investigations to determine whether surgical treatment is feasible. Surgical feasibility is determined by identifying the location and number of seizure foci and their relationship to eloquent areas of the brain. Good surgical outcome depends on complete resection of seizure foci without any damage to eloquent brain function. Various noninvasive and invasive techniques are used in the presurgical evaluation of patients with epilepsy that include imaging techniques, electrophysiologic studies, and tests to determine functional areas. Understanding of the principles of seizure localization and of the effects of anesthetic drugs on the various preoperative investigations is essential for patient management. In this review article, we discuss the role of the anesthesiologist in patient management during many of these investigations and the role of anesthetic drugs to aid in the localization of the seizure focus and of determining eloquent brain function.

Background Perioperative hypothermia has been reported to increase the occurrence of cardiovascular complications. By increasing the activity of sympathetic nervous system, perioperative hypothermia also has the potential to increase cardiac injury and dysfunction associated with subarachnoid hemorrhage. Methods The Intraoperative Hypothermia for Aneurysm Surgery Trial randomized patients undergoing cerebral aneurysm surgery to intraoperative hypothermia (n = 499, 33.3 degrees +/- 0.8 degrees C) or normothermia (n = 501, 36.7 degrees +/- 0.5 degrees C). Cardiovascular events (hypotension, arrhythmias, vasopressor use, myocardial infarction, and others) were prospectively followed until 3-month follow-up and were compared in hypothermic and normothermic patients. A subset of 62 patients (hypothermia, n = 33; normothermia, n = 29) also had preoperative and postoperative (within 24 h) measurement of cardiac troponin-I and echocardiography to explore the association between perioperative hypothermia and subarachnoid hemorrhage-associated myocardial injury and left ventricular function. Results There was no difference between hypothermic and normothermic patients in the occurrence of any single cardiovascular event or in composite cardiovascular events. There was no difference in mortality (6%) between groups, and there was only a single primary cardiovascular death (normothermia). There was no difference between hypothermic and normothermic patients in postoperative versus preoperative left ventricular regional wall motion or ejection fraction. Compared with preoperative values, hypothermic patients had no postoperative increase in cardiac troponin-I (median change 0.00 microg/l), whereas normothermic patients had a small postoperative increase (median change + 0.01 microg/l, P = 0.038). Conclusion In patients undergoing cerebral aneurysm surgery, perioperative hypothermia was not associated with an increased occurrence of cardiovascular events.

Background Although hypothermia and barbiturates improve neurologic outcomes in animal temporary focal ischemia models, the clinical efficacy of these interventions during temporary occlusion of the cerebral vasculature during intracranial aneurysm surgery (temporary clipping) is not established. Methods A post hoc analysis of patients from the Intraoperative Hypothermia for Aneurysm Surgery Trial who underwent temporary clipping was performed. Univariate and multivariate logistic regression methods were used to test for associations between hypothermia, supplemental protective drug, and short- (24-h) and long-term (3-month) neurologic outcomes. An odds ratio more than 1 denotes better outcome. Results Patients undergoing temporary clipping (n = 441) were assigned to intraoperative hypothermia (33.3 degrees +/- 0.8 degrees C, n = 208) or normothermia (36.7 degrees +/- 0.5 degrees C, n = 233), with 178 patients also receiving supplemental protective drug (thiopental or etomidate) during temporary clipping. Three months after surgery, 278 patients (63%) had good outcome (Glasgow Outcome Score = 1). Neither hypothermia (P = 0.847; odds ratio = 1.043, 95% CI = 0.678-1.606) nor supplemental protective drug (P = 0.835; odds ratio = 1.048, 95% CI = 0.674-1.631) were associated with 3-month Glasgow Outcome Score. The effect of supplemental protective drug did not significantly vary with temperature. The effects of hypothermia and protective drug did not significantly vary with temporary clip duration. Similar findings were made for 24-h neurologic status and 3-month Neuropsychological Composite Score. Conclusion In the Intraoperative Hypothermia for Aneurysm Surgery Trial, neither systemic hypothermia nor supplemental protective drug affected short- or long-term neurologic outcomes of patients undergoing temporary clipping.

BACKGROUND The most common anesthetic technique for patients undergoing insertion of deep brain stimulators (DBS) is local anesthesia with or without conscious sedation as this facilitates intraoperative microelectrode recordings (MERs) for target localization. However, general anesthesia (GA) may be needed in some of the patients especially those with dystonia. The purpose of our study was to determine the effects of GA on MERs from pallidal neurons in patients with dystonia undergoing DBS implantation surgery. METHODS After IRB approval, we retrospectively reviewed the medical records of all patients who had insertion of DBS from January 2009 to December 2013. Data collected and analyzed included demographics, indications for DBS, targets of insertion, MER, and anesthetic management. From the records we identified patients with dystonia who received GA for DBS insertion. We then compared the MER data under GA with the data from patients who had surgery under local anesthesia only during the same time period. Because of the small sample size, the effects of various anesthetic regiments on MER and localization of target nuclei were compared qualitatively. RESULTS Of the 435 patients who underwent DBS insertion during the study period, 20 (4.3%) patients had GA for the procedure. Dystonia was the most common indication for GA (16/20 patients, 80%). Good-quality MER data obtained from 10 patients with dystonia under GA was compared with 8 patients who had no sedation for the procedure. Administration of GA made target localization difficult due to suppression of both spontaneous and evoked neuronal discharges from internal globus pallidus. Although not studied systematically, propofol (>100 mcg/kg/min) seemed to suppress pallidal discharges more than GA with a lower dose of propofol (

A hypersensitivity reaction, either anaphylactic or anaphylactoid, is a well-known adverse effect following intravenous and oral administration of vancomycin. The authors report a case of circulatory collapse and its management after the topical application of vancomycin powder during spinal instrumentation surgery. A 52-year-old woman with breast cancer and metastasis to her spine underwent a vertebrectomy of the T-10 vertebra with instrumented reconstruction from T-8 to T-12. The patient was hemodynamically stable during most of the procedure despite a 2-L blood loss requiring administration of crystalloids, colloids, packed red blood cells, and fresh-frozen plasma. During closure of the subcutaneous layer, there was a sudden drop in blood pressure from 120/60 to 30/15 mm Hg and an increase in heart rate from 95 to 105 bpm. No skin erythema or rash was visible, and there was no bronchospasm or increase in airway pressure. The patient was treated with fluids, boluses of ephedrine, phenylephrine, and adrenaline. The operation was completed and the patient woke up neurologically intact but did require blood pressure support with a norepinephrine infusion for the next 4 hours. She was discharged from hospital in a good clinical state on the 4th postoperative day. It was speculated that the rapid absorption of vancomycin powder applied on the surgical wound caused an anaphylactoid reaction and the circulatory collapse. With an increase in the use of topical vancomycin in surgical wounds, communication and awareness among all intraoperative team members is important for rapid diagnosis of an adverse reaction and for appropriate management.

A 79-year-old woman with no history of myocardial ischemia presented with symptoms of pituitary apoplexy for which an urgent transsphenoidal resection of the pituitary gland was undertaken. The nasal passages were prepared with topical application of epinephrine followed by injection of what was presumed to be 1% lidocaine containing 10 microg/ml(-1) of epinephrine. After only 1.5 mL of the solution had been injected, she developed a hypertensive crisis, which was immediately treated. Postoperatively, she developed a myocardial infarction. The risks associated with the use of vasopressors are reviewed and suggestions for their safe use are presented.

We retrospectively reviewed the anesthetic management, complications, and discharge time of 241 patients undergoing awake craniotomy for removal of intracranial tumor to determine the feasibility of early discharge. The results were analyzed by using univariate analysis of variance and multiple logistic regression. The median length of stay for inpatients was 4 days. Fifteen patients (6%) were discharged 6 h after surgery and 76 patients (31%) were discharged on the next day. Anesthesia was provided by using local infiltration supplemented with neurolept anesthesia consisting of midazolam, fentanyl, and propofol. There was no significant difference in the total amount of sedation required. Overall, anesthetic complications were minimal. One patient (0.4%) required conversion to general anesthesia and one patient developed a venous air embolus. Fifteen patients (6%) had self-limiting intraoperative seizures that were short-lived. Of the 16 patients scheduled for ambulatory surgery, there was one readmission and one unanticipated admission. It may be feasible to discharge patients on the same or the next day after awake craniotomy for removal of intracranial tumor. However, caution is advised and patient selection must be stringent with regards to the preoperative functional status of the patient, tumor depth, surrounding edema, patient support at home, and ease of access to hospital for readmission.It may be feasible to perform awake craniotomies for removal of intracranial tumor as an ambulatory procedure; however, caution is advised. Patient selection must be stringent with respect to the patient's preoperative functional status, tumor depth, surrounding edema, patient support at home, and ease of access to hospital for readmission.

Summary There are numerous and continuous advances in the treatment of intracranial vascular lesions. The role of the anesthesiologist will remain vital in the overall management of these patients by ensuring safety in this remote environment, with the use of all standard and required monitoring, the administration of the appropriate anesthetic, and careful vigilance and treatment of complications.

Objective Frameless navigation systems represent a huge step forward in the surgical treatment of intracranial pathological conditions but lack the ability to provide real-time imaging feedback for assessment of postoperative results, such as catheter positions and the extent of tumor resections. An open magnetic resonance imaging system for intracranial surgery was developed in Toronto, by a multidisciplinary team, to provide real-time intraoperative imaging. Methods The preliminary experience with a 0.2-T, vertical-gap, magnetic resonance imaging system for intraoperative imaging, which was developed at the University of Toronto for the surgical treatment of patients with intracranial lesions, is described. The system is known as the image-guided minimally invasive therapy unit. Results Between February 1998 and March 1999, 36 procedures were performed, including 21 tumor resections, 12 biopsies, 1 transsphenoidal endoscopic resection, and 2 catheter placements for Ommaya reservoirs. Three complications were observed. All biopsies were successful, and the surgical goals were achieved for all resections. Problems included restricted access resulting from the confines of the magnet and the imaging coil design, difficulties in working in an operating room that is less spacious and familiar, inconsistent image quality, and a lack of nonmagnetic tools that are as effective as standard neurosurgical tools. Advantages included real-time imaging to facilitate surgical planning, to confirm entry into lesions, and to assess the extent of resection and intraoperative and immediate postoperative imaging to confirm the extent of resections, catheter placement, and the absence of postoperative complications. Conclusion Intraoperative magnetic resonance imaging has great potential as an aid for intracranial surgery, but a number of logistic problems require resolution.

Developments in technology have led to the merger of two distinct environments, that of magnetic resonance imaging and that of the operating room. The major advantage of this merger for neurosurgical procedures is the ability to perform real-time imaging to help guide surgery. This review discusses the role of the anesthesiologist in the planning and administration of safe anesthesia in this new and challenging environment.

We evaluated the effectiveness of alfentanil and fentanyl in stimulating epileptogenic activity during surgery for intractable temporal lobe epilepsy under general anesthesia. Ten patients received a standardized anesthetic induction with IV fentanyl 5 mg/kg, propofol 3‐5 mg/kg, and atracurium 0.5 mg/kg. Maintenance was with isoflurane, 70% N2O/30% O2, and an atracurium infusion. After dural opening, droperidol 0.02 mg/kg was administered IV. Both inhaled anesthetics were discontinued and verified to be at 0 endtidal concentration before the study. Baseline electrocorticography over the surface of the temporal lobe and depth electrode recordings in the amygdala and hippocampus were obtained, followed by 10 min of recording before and after the IV administration of both alfentanil 50 mg/kg and fentanyl 10 mg/kg. Any changes in cardiovascular variables were documented. The number of interictal epileptiform spikes at the most active site for each patient was tabulated before and after the administration of each drug. Both alfentanil and fentanyl induced an increase in spike activity in all patients. Alfentanil was more potent, increasing the median number of spikes per epoch from 18 to 58, compared with fentanyl (20 to 42 spikes) (P , 0.05). Alfentanil had a shorter duration of action (4.9 6 1.3 min) compared with fentanyl (8.5 6 2 min) (P , 0.009). In nine patients, the most active site was the hippocampus or amygdala. There was a decrease in mean blood pressure, but only after the administration of alfentanil (P , 0.05). Two patients had electrographic evidence of seizure activity. These opioids can be used to assist in the localization of the epileptogenic focus during surgery. Implications: Both alfentanil and fentanyl activate epileptiform activity in patients with temporal lobe epilepsy. These opioids can be used to assist in the localization of the epileptogenic focus during surgery.

To assess the cerebral oximeter, which measures regional oxygen saturation (rSO2) continuously and noninvasively, as a cerebral monitor during carotid endarterectomy (CEA). The rSO2 was compared with Somatosensory Evoked Potentials (SSEPs) as an indicator for shunting and as a predictor of postoperative neurological deficits.Seventy-two consenting patients undergoing CEA with general anaesthesia were studied. Normocarbia, normothermia and normotension were maintained. Cerebral monitoring consisted of bilateral median nerve SSEPs and the INVOS 3100 cerebral oximeter with the sensor pad placed on the ipsilateral forehead. Decreases in SSEP amplitude of 50% and in rSO2 of 10% were considered clinically significant. Neurological assessment was performed at emergence from anaesthesia, 24 hr postoperatively and at discharge. The rSO2 changes were compared with SSEP changes and with neurological deficits. Statistical analysis was with chi square and analysis of variance P0.05 was considered significant.During carotid artery clamping, rSO2 decreased from 72 +/- 8% to 68 +/- 9% and mean arterial blood pressure increased from 92 +/- 14 mmHg to 98 +/- 14 mmHg. In four patients, the carotid artery was shunted because of SSEP changes after cross-clamping. Five patients hador = 10% decreases in rSO2 following clamp application. Changes in both SSEP and rSO2 occurred in two patients. Three of the four shunted patients had transient postoperative neurological deficits. One patients had a transient deficit without changes in either monitor. There were no persistent postoperative deficits. Compared with SSEPs, rSO2 had a sensitivity of 50% and a specificity of 96%.Clinical experience with this evolving technology is ongoing. Its role in neurovascular procedures has yet to be established.

Background The Wada procedure (the intracarotid amobarbital procedure) has been used widely to evaluate the hemispheric dominance of language and memory before temporal lobe surgery in patients with medically refractory seizures. Because of repeated shortage of sodium amobarbital, attempts have been made to find a suitable alternative to sodium amobarbital. The aim of our study was to review our experience with the use of etomidate as an alternative to sodium amobarbital for Wada testing in patients with medically refractory seizures. Methods After the ethics approval, we retrospectively reviewed the charts of 29 consecutive patients who underwent Wada test with etomidate. Data from a total of 50 hemispheric injections were reviewed and analyzed. This included the electroencephalographic and motor effects of etomidate injection and their time course (onset and recovery), Wada test results (language laterality and memory performance), and all adverse events during the procedure. Results Intracarotid administration of etomidate produced a predictable electroencephalographic and motor effects in all patients. The desirable effect was seen with a single bolus dose of 2 mg followed by an infusion. Shivering was the most common side effect, seen in all the patients. Successful testing was possible in nearly all patients without any major side effects. The "pass rate" of valid tests was in good accord with our previous experience with the use of sodium amobarbital. Conclusion From our experience, etomidate is a safe alternative to sodium amobarbital for the Wada test for determining the hemispheric dominance for speech and in predicting the memory outcome.

Objective: To describe the application of intraoperative monitoring techniques during aneurysm surgery and to discuss the advantages and limitations of these techniques in prevention of postoperative neurologic deficits. Methods: Articles found in the literature through PubMed for the time frame 1980-2011 and the authors' personal files were reviewed. Results: Various techniques for detection of vascular insufficiency are available, including direct methods to measure cerebral blood flow and indirect methods to evaluate the integrity of neurologic pathways. Conclusions: The choice of monitoring modality should be governed by the vessel and by the vascular territory most at risk during the planned procedure with proper awareness of the potential limits related to each technique. Aneurysm surgery monitoring should help to address issues of continuity and provide a morphologic and functional assessment. Although the use of monitoring devices is still not routine in aneurysm surgery and no standards have been established, combining different monitoring techniques is crucial to optimize aneurysm surgery and avoid or minimize complications. © 2012 Elsevier Inc. All rights reserved.

The purpose of this study was to compare and assess the ability of two different evoked potential (EP) modalities, median nerve somatosensory evoked potentials (SSEP) and brainstem auditory evoked potentials (BAEP) in monitoring for cerebral ischaemia and in predicting neurological outcome during posterior fossa aneurysm surgery. During 70 procedures, patients were monitored with both SSEP and BAEP Temporary occlusion of an artery was used in 52 patients and permanent occlusion in 21 patients. A change was defined as a greater than 50% decrease in amplitude and/or an increase in latency greater than 1 msec of the N20 (cortical waveform) for SSEP monitoring and of the fifth peak for BAEP monitoring. Neurological assessment of the patient was performed immediately on emergence, after 24 hr and at the time of discharge. In total, 14 patients had an SSEP change which predicted a neurological deficit in eight patients (57%). Ten patients had a change in BAEP; six had a neurological deficit (60%). Five patients had a change in both, two had a deficit (40%). The incidence of false negative results (a neurological deficit but no EP change) for both modalities was 20% (SSEP 47%, BAEP 60%). The incidence of false positive results (an EP change but no deficit) was 13% overall (SSEP 11%, BAEP 7%). All patients who had a permanent EP change developed a neurological deficit. We did not find a difference in the ability of SSEP compared with BAEP in predicting neurological deficits but, using both modalities, the incidence of false negative results was decreased. In conclusion, dual modality monitoring should be used whenever possible as neither modality alone was better than the other in detecting cerebral ischaemia and in predicting neurological deficits.

We report the anesthetic management of an adult patient undergoing cerebral revascularization surgery for moyamoya syndrome complicating sickle-cell disease (SCD). We present a 25 year-old male of African ethnicity with homozygous SCD who was experiencing worsening ischemic neurologic symptoms culminating in intraventricular hemorrhage from rupture of moyamoya vessels. Despite an extracranial–intracranial superficial temporal artery–middle cerebral artery bypass that was angiographically patent postoperatively, he subsequently required an intracranial omental transplant to improve cerebral blood flow to the anterior cerebral artery territory. Prior to both cerebral revascularization procedures, the patient had continued with his regularly scheduled red blood cell exchange transfusion. The importance of normothermia, normocarbia, normotension, and normovolemia is emphasized in the neuroanesthetic management. We conclude that the safe and efficacious operative treatment of moyamoya disease, using both direct and indirect revascularization procedures, is being increasingly described, and therefore anesthesiologists are likely to encounter similar cases in the future and need to be aware of the surgical procedures and perioperative implications. The overall principles of safe anesthesia (normotension, normocarbia, good oxygenation, normothermia, normovolemia) for patients with SCD also applies to patients with moyamoya. During a craniotomy, certain deviations from these are needed (hyperventilation and mannitol diuresis for brain volume reduction, induced hypothermia or manipulations of arterial blood pressures) but they can be safely used with careful monitoring of the patient.

Neurolept anaesthesia is used during awake craniotomy for epilepsy surgery. This study compares analgesia, sedation and the side effects of the newer opioids sufentanil and alfentanil, with those of fentanyl in patients undergoing awake craniotomy. Thirty patients were randomized into three groups, each received droperidol, dimenhydrinate and the chosen opioid as a bolus followed by an infusion. The opioid doses used were fentanyl 0.75 microgram.kg-1 plus 0.01 microgram.kg-1 x min-1; sufentanil 0.075 microgram.kg-1 plus 0.0015 microgram.kg-1 x min-1, and alfentanil 7.5 micrograms.kg-1 plus 0.5 microgram.kg-1 x min-1. There were no differences in the requirements for droperidol, dimenhydrinate or in the incidence of complications among the three groups. The total doses of the opioids required were fentanyl 4.9 +/- 1.3 micrograms.kg-1, sufentanil 0.6 +/- 0.2 microgram.kg-1 and alfentanil 149 +/- 36 micrograms.kg-1. Two patients became uncooperative requiring general anesthesia. The conditions for surgery, electrocorticography and for stimulation testing were satisfactory in all other patients. We conclude that the newer opioids did not offer any benefit over fentanyl.

Monitoring of cardiovascular, respiratory, and evoked potential parameters has been advocated during posterior fossa surgery to detect brainstem ischemia that may result from surgical manipulations. We report here our retrospective and smaller prospective experience of spontaneous ventilation as a monitor in patients undergoing vascular surgical procedures in the posterior fossa. Forty patients' charts were reviewed retrospectively, and 10 patients were studied prospectively. Respiratory changes in the retrospectively studied group occurred in 9 patients. Four patients developed apnea during temporary occlusion of the vertebral artery. These respiratory changes were associated with simultaneous cardiovascular changes in only 2 patients, and of the 13 patients monitored with evoked potentials, only 2 had simultaneous evoked potential changes. In the prospectively studied group, respiratory changes occurred in 4 patients. Three patients (2 with apnea during temporary occlusion) had a simultaneous change in evoked potentials but no cardiovascular changes. One patient had a change in all three parameters. Allowing our patients to breathe spontaneously provided an early and rapid indication of brainstem ischemia, especially during the temporary occlusion of the vertebral basilar artery system.

Because it is common to manipulate PaCO2 during neurosurgery, it is essential to characterize the relationship between cerebral blood flow (CBF) and changes in PaCO2. The purpose of this study was to investigate the effects of propofol-N2O anesthesia on the CBF response to changes in PaCO2 in healthy subjects. In seven patients, anesthesia was induced with propofol 2.0-2.5 mg/kg and then maintained with a propofol infusion of 12 mg.kg-1.h-1 for 10 min and then 9 mg.kg-1.h-1 for 10 min and then was reduced to 3-6 mg.kg-1.h-1 for the remainder of the study. The subjects' lungs were ventilated with N2O in O2 (FIO2 0.3) to the end-tidal CO2 present before anesthesia, and then CBF was measured using intravenous 133Xe and ten scintillation counters, five over each cerebral hemisphere. ETCO2 then was increased to 50 mmHg and CBF measurement repeated; ETCO2 then was reduced to 30 mmHg and CBF measurement repeated. Concurrent with each CBF measurement, arterial blood was sampled for PaCO2 and hemoglobin measurement. CBF at normocapnia (PaCO2 42 +/- 2 mmHg) was 33 +/- 7 ml.100 g-1.min-1, which increased to 58 +/- 10 ml.100 g-1.min-1 and decreased to 19 +/- 4 ml.100 g-1.min-1 on increasing PaCO2 (53 +/- 4 mmHg) and decreasing PaCO2 (31 +/- 2 mmHg), respectively. Both the PaCO2 and CBF values were statistically different from those measured at any other time (CBF P less than 0.002, PaCO2 P less than 0.001). The slope of CBF versus PaCO2 was 1.56 ml.100 g-1.min-1.mmHg.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro studies suggest that the preservatives methylparaben and propylparaben included in some multidose vials of succinylcholine are the cerebral vasodilators responsible for the increases in intracranial pressure (ICP) documented after succinylcholine administration. To test this hypothesis, we measured cerebral blood flow (CBF) and cerebral blood flow velocity (CBFV) with inhaled 133Xenon and transcranial Doppler respectively in healthy humans before and after the intravenous administration of methylparaben and propylparaben. We found no change in either CBF or CBFV after the paraben injections and therefore conclude that it is unlikely that the rise in ICP seen with succinylcholine is caused by cerebral arterial vasodilatation from the preservatives methylparaben and propylparaben.

OBJECTIVE: We examined the incidence of perioperative fever and its relationship to outcome among patients enrolled in the Intraoperative Hypothermia for Aneurysm Surgery Trial. METHODS: One thousand patients with initial World Federation of Neurological Surgeons grades of I to III undergoing clipping of intracranial aneurysms after subarachnoid hemorrhage were randomized to intraoperative normothermia (36 degrees C-37 degrees C) or hypothermia (32.5 degrees C-33.5 degrees C). Fever (> or =38.5 degrees C) and other complications (including infections) occurring between admission and discharge (or death) were recorded. Functional and neuropsychologic outcomes were assessed 3 months postoperatively. The primary outcome variable for the trial was dichotomized Glasgow Outcome Scale (good outcome versus all others). RESULTS: Fever was reported in 41% of patients. In 97% of these, fever occurred in the postoperative period. The median time from surgery to first fever was 3 days. All measures of outcome were worse in patients who developed fever, even in those without infections or who were World Federation of Neurological Surgeons grade I. Logistic regression analyses were performed to adjust for differences in preoperative factors (e.g., age, Fisher grade, initial neurological status). This demonstrated that fever continued to be significantly associated with most outcome measures, even when infection was added to the model. An alternative stepwise model selection process including all fever-related measures from the preoperative and intraoperative period (e.g., hydrocephalus, duration of surgery, intraoperative blood loss) resulted in the loss of significance for dichotomized Glasgow Outcome Scale, but significant associations between fever and several other outcome measures remained. After adding postoperative delayed ischemic neurological deficits to the model, only worsened National Institutes of Health Stroke Scale score, Barthel Activities of Daily Living index, and discharge destination (home versus other) remained independently associated with fever. CONCLUSION: These findings suggest that fever is associated with worsened outcome in surgical subarachnoid hemorrhage patients, although, because the association between fever and the primary outcome measure for the trial is dependent on the covariates used in the analysis (particularly operative events and delayed ischemic neurological deficits), we cannot rule out the possibility that fever is a marker for other events. Only a formal trial of fever treatment or prevention can address this issue.

A case is reported of a young woman in whom the diagnosis of a phaeochromocytoma was made after a major stroke. Preoperative preparation included the introduction of phenoxybenzamine, 10 mg · day− 1, and propranolol, 80 mg · day− 1, over a two-week period. The presence of cerebrovascular disease and the marked orthostatic changes in blood pressure and heart rate to low-dose phenoxybenzamine prevented the establishment of full alpha blockade. Incomplete alpha blockade probably contributed to the hypertensive response to manipulation of the tumour (220/150 mmHg) and hypotension occurred after removal of the tumour (80/45 mmHg). An anaesthetic technique was chosen to provide haemodynamic stability as well as protection against cerebral ischaemia. Invasive haemodynamic monitoring, a four-channel processed electroencephalograph and somatosensory evoked potentials were used to accomplish these goals.

There is no consensus as to the most appropriate monitor for detecting ischemia during carotid endarterectomy. Accordingly, simultaneous 16-channel continuous electroencephalogram (EEG) and somatosensory evoked potential (SSEP) monitoring were performed in 64 normocapnic patients undergoing carotid endarterectomy and anesthetized with isoflurane or halothane-nitrous oxide (supplemented with fentanyl). Recordings were obtained before, during, and for 15 min after cross-clamping of the internal carotid artery. Internal shunt was not used in any patient, regardless of EEG and SSEP changes. Significant amplitude reduction in the cortical component of the primary negative peak (greater than 50%) in SSEP occurred in 6 patients, and an increase in central conduction time (CCT) (greater than 1 ms) occurred in 5 patients. Major EEG changes occurred in 6 patients, 4 of whom also had SSEP changes. Two patients had transient neurologic deficits postoperatively, with both having SSEP changes (amplitude reduction greater than 50%), whereas one had EEG changes. Based on these observations, the relative sensitivity and specificity for EEG and SSEP (amplitude reduction greater than 50%) in detecting postoperative neurologic deficits were 50% and 92% for EEG and 100% and 94% for SSEP, respectively, differences that were not statistically significant. Regarding SSEP, the use of latency change (CCT) as a criterion was associated with a sensitivity of 0% (P = 0.046 from sensitivity of amplitude) and a specificity of 87% (P = 0.17 from specificity of amplitude).(ABSTRACT TRUNCATED AT 250 WORDS)

Electrocardiographic (ECG) changes are reported frequently after subarachnoid haemorrhage (SAH). The aim of this study was to investigate the functional significance of ECG changes by echocardiographic assessment of cardiac function. Forty-five patients with intracranial aneurysms were studied. All patients had a 12-lead ECG and a two-dimensional echocardiogram. After patients with an history of chronic cardiac disease (n = 4) were excluded, only four patients were found to have wall motion abnormalities. These patients had only minor ECG abnormalities, but severe neurological dysfunction. Conversely, patients with other ECG abnormalities including the deep inverted T waves associated usually with SAH, had normal echocardiograms. We conclude that the ECG is not an accurate predictor of myocardial function after SAH and that myocardial dysfunction is related more closely to severity of neurological condition.

This study compared the effects of general and regional anesthesia on cognitive and psychosocial functioning in elderly persons. Sixty-four patients between 60 and 86 yr of age undergoing knee arthroplasty were randomly assigned to receive either general or regional anesthesia. A battery of psychometric tests, including the Satz-Mogel form of the Wechsler Adult Intelligence Scale-Revised, the Wechsler Memory Scale-Revised and the Sickness Impact Profile, and various neuropsychological measures were administered by a blinded observer just before surgery and again 3 months later. Analyses of covariance revealed improvements in most measures that were equivalent between groups. The results indicated that there were no cognitive or psychosocial effects of general or regional anesthesia after 3 months in elderly persons undergoing knee arthroplasty. In this patient population, general anesthesia poses no more risk to long-term mental function than regional anesthesia.

To compare the recovery profiles, efficacy and safety of remifentanil and morphine for transitional analgesia with fentanyl in patients undergoing elective craniotomy for supratentorial mass lesions.Ninety-one patients were enrolled in this prospective, randomized, multicentre study. Anesthesia was induced with thiopental and remifentanil (1.0 micro g x kg(-1) bolus and a 1 micro g x kg(-1) x min(-1) infusion) or fentanyl (1 micro g x kg(-1) bolus and a 1.0 micro g x kg(-1) x min(-1) infusion). The opioid infusion continued until the level of anesthesia was deemed appropriate for intubation. Anesthesia was maintained with N(2)O/O(2), isoflurane 0.5 MAC and remifentanil 0.2 micro g x kg(-1) x min(-1) or fentanyl 0.04 micro g x kg(-1) x min(-1). At bone flap replacement, either morphine 0.08 mg x kg(-1) (remifentanil group) or saline (fentanyl group) was given.Systolic blood pressure was greater in those receiving fentanyl during induction (145.6 +/-17.5 mmHg vs 128.8 +/-18.3 mmHg; P = 0.006) and intubation (126.9 +/-17.1 vs 110.9 +/-16.5 mmHg; P0.001). Median time to tracheal extubation was similar but less variable in the remifentanil group (remifentanil = 8 min: range = 2-44 min; fentanyl = 8 min: range = 1-732 min). The fentanyl patients required a longer time to achieve the first normal neurological score (fentanyl = 38.0 min; remifentanil = 26.0 min; P = 0.035). Both the anesthesiologists and the recovery room nurses rated remifentanil better with respect to level of consciousness. Analgesics were required earlier in patients receiving remifentanil; median time 0.5 vs 1.08 hr, P0.001.Remifentanil is a suitable alternative to fentanyl in supratentorial craniotomy. Time to preoperative neurological recovery is faster and morphine provides some transitional analgesia without compromising the quality of recovery.

To review the experience of one tertiary care institution with somatosensory evoked potential (SSEP) monitoring during spinal surgery in order to assess the ability to monitor and predict neurological outcome effectively.Records of all patients undergoing spinal surgery during 18 mo were retrospectively reviewed. Information from the patient chart included preoperative neurological status, surgical procedure, anaesthetic management, and postoperative neurological outcome. Information regarding the techniques used and interpretation of all SSEP tracings were obtained from evoked potential data sheets completed for each patient. The incidences of clinically important SSEP changes and new postoperative neurological deficits were analysed.Somatosensory evoked potential monitoring of the lower and upper extremities with non invasive techniques was used in 309 patients undergoing surgery on the cervical (88), thoracic (52), and lumbar spine (169). Thirty seven patients (11%) did not have suitable tracings for interpretation and 17 (5.5%) had baseline tracings described as poor. An intraoperative SSEP change occurred in 16 patients (6%) with SSEP and seven (2.6%) had a new neurological deficit postoperatively. Three persistent deficits were predicted by permanent SSEP change, and one transient deficit by a transient SSEP change. False positive results occurred in 12 patients (4.4%) and false negative results occurred in three (1.1%), with a sensitivity of 57% and a specificity of 95%. The incidence of SSEP changes was greater in the thoracic (18%) than in the cervical (1.2%) or lumbar (5.4%) groups (P0.05).Effective SSEP monitoring was possible despite the many factors which may have interfered with monitoring. More improvements in the techniques and conditions of monitoring are needed to decrease the incidence of false positive and negative results.

To report our clinical experience with a new blood processing device which uses ultrafiltration. We assessed safety and efficacy by evaluating: 1 ) the quality and the quantity of intraoperative shed blood processed and reinfused to the patient 2) homologous blood requirements 3) clinical status of the patient post-transfusion.With Ethics Committee approval, the ultrafiltration device was used in six consenting patients undergoing major elective spinal surgery. Blood samples for haematology and biochemistry tests were collected from patients post-induction of anaesthesia (baseline), 1 hr and 24 hr post-autotransfusion. Volumes of blood collected and processed, and all autologous and homologous transfusions were recorded. Patients were assessed post-operatively for any adverse effects.Five patients had donated blood preoperatively. One patient required homologous blood products in addition to autologous blood. In two patients, the filtration cartridge became blocked and required changing midprocessing. No patient sustained device-related complications. One patient had postoperative haematuria which resolved spontaneously within two hours.The ultrafiltration device was safe and effective in reducing homologous blood requirements in six patients undergoing elective spinal surgery. Further evaluation of the ultrafiltration device will be necessary, especially in view of the blockage of the filtration cartridge.

The field of radiology is a rapidly expanding and growing area in the investigation and treatment of central nervous system diseases. The role of the anaesthetist will continue to be important in the management of these patients. The anaesthetist must be prepared to modify and adapt to the changes in techniques, procedures, and to the requirements of the neuroradiologist and patient.

Study Objective: To review the anesthetic management and the occurrence and treatment of complications in patients undergoing interventional neuroradiologic procedures for the treatment of intracranial vascular lesions. Design: Retrospective chart review of 115 charts from 1988 to 1992. Setting: University hospital. Measurements and Main Results: Charts were reviewed for information regarding the anesthetic management, monitoring techniques, complications, treatment of complications, and clinical outcome. Group 1 patients (n = 92) were managed by an anesthesiologist; 8 received general anesthesia and 84 had conscious sedation. Group 2 patients (n = 70) were cared for by a neuroradiologist; 37 received intravenous analgesia (fentanyl) and 33 received no sedation other than premedication (benzodiazepine). No episodes of anesthetic or drug-related complications were documented. Complications directly related to technical aspects of the procedure were documented in 33 (20%) cases, 19 (21%) in Group 1 and 14 (20%) in Group 2. These complications consisted of ischemia (n = 14), hemorrhage (n = 9), catheter misplacement (n = 8), and pulmonary embolism (n = 2). Four patients, two in each group, required urgent assessment by an anesthesiologist. Conclusions: There was no difference in the incidence of complications between the two groups. As the use of interventional neuroradiology increases, the anesthesiologist will be more involved in the elective or emergency treatment of these patients.