Use of etomidate, temporary arterial occlusion, and intraoperative angiography in surgical treatment of large and giant cerebral aneurysms

Treatment of giant intracranial aneurysms using the Pipeline flow-diverting stent: Long-term results from the International Retrospective Study of the Pipeline Embolization Device (IntrePED) study

BACKGROUND

Traditional endovascular treatments of giant intracranial aneurysms are associated with high rates of complications and retreatment. Our objective was to examine the safety and long-term efficacy of the Pipeline Embolization Device for treatment of these aneurysms.

METHODS

This retrospective study using the IntrePED database included all patients with giant intracranial aneurysms treated with the Pipeline device between July 2008 and February 2013. Efficacy outcomes were stratified by using the Raymond-Roy Occlusion Classification. Predefined safety outcomes included spontaneous rupture of the target aneurysm; ipsilateral intracranial hemorrhage; ischemic stroke; parent artery stenosis; and sustained cranial neuropathy.

RESULTS

Sixty-six embolizations were performed to treat 63 giant intracranial aneurysms (including 2 ruptured): 49 (77.8%) in the anterior and 14 (22.2%) in the posterior circulation. The median follow-up was 22.4 (0.1-60.5) months. Class I angiographic occlusion was achieved in 72.0% (36/50). The neurological morbidity/mortality rate was 23.8% (15/63), with higher rates in the posterior circulation than in the anterior circulation (22.4% vs. 28.6%). Among seven deaths, five had neurological causes. The procedure-related neurological morbidity and mortality rates were 22.7% (15/66) and 7.6% (5/66), respectively. The spontaneous rupture rate was 4.5% (3/66). Two spontaneous ruptures (1 death), 4/4 postprocedural intracranial hemorrhages, and 6/9 ischemic events occurred within 30 days. In-stent stenosis and new-onset cranial neuropathy were not observed during the angiographic follow-up period.

CONCLUSIONS

Although procedure-related neurological morbidity/mortality rates were not insignificant, this study confirms the feasibility and long-term efficacy of the Pipeline Embolization Device to treat giant intracranial aneurysms.

Electroencephalographic Burst-Suppression, Perioperative Neuroprotection, Postoperative Cognitive Function, and Mortality: A Focused Narrative Review of the Literature

Burst-suppression is an electroencephalographic pattern that results from a diverse array of pathophysiological causes and/or metabolic neuronal suppression secondary to the administration of anesthetic medications. The purpose of this review is to provide an overview of the physiological mechanisms that underlie the burst-suppression pattern and to present in a comprehensive way the available evidence both supporting and in opposition to the clinical use of this electroencephalographic pattern as a therapeutic measure in various perioperative settings.

Temporary Clipping of the Intracavernous Internal Carotid Artery: A Novel Technique for Proximal Control

BACKGROUND

Securing proximal control in complex paraclinoid aneurysm surgery through traditional techniques may be challenging and risky in certain situations. Advancements of anatomical knowledge of the cavernous sinus (CS) and hemostasis have made it more accessible as a surgical option.

OBJECTIVE

To describe the technique of temporary clipping of the horizontal segment of the intracavernous internal carotid artery (IC-ICA) in preparation for permanent clipping of complex paraclinoid aneurysms.

METHODS

Through an extradural pretemporal approach, the lateral wall of the CS is exposed. The dura between the trochlear nerve and V1 is opened, and access is made to the horizontal segment of the IC-ICA. After circumferential dissection, the temporary clip can be introduced to the artery, and the extradural clinoidectomy can be continued under secured proximal control.

RESULTS

Seven patients with complex paraclinoid aneurysms were treated between May 2013 and May 2016 by the senior author. Temporary clipping of the IC-ICA was performed in all cases. Average time to achieve proximal control was 22.6 min (22.6 ± 13.8). One patient developed transient oculomotor palsy postoperatively. There were no other complications.

CONCLUSION

When the exposed clinoidal segment of the internal carotid artery does not offer sufficient proximal space for temporary clipping, the extradural approach can be extended to the horizontal portion of the IC-ICA. In our experience, this technique is a quick, reliable, and safe alternative to the classical modalities of temporary occlusion.

The Neuroprotective Effect of Thiopental on the Postoperative Neurological Complications in Patients Undergoing Surgical Clipping of Unruptured Intracranial Aneurysm: A Retrospective Analysis

Although thiopental improved neurological outcomes in several animal studies, there are still insufficient clinical data examining the efficacy of thiopental for patients undergoing surgical clipping of unruptured intracranial aneurysm (UIA). This study validated the effect of thiopental and investigated risk factors associated with postoperative neurological complications in patients undergoing surgical clipping of UIA. In total, 491 patients who underwent aneurysm clipping were included in this retrospective cohort study. Data regarding demographics, aneurysm characteristics, and use of thiopental were collected from electronic medical records. Propensity score matching and logistic regression analysis were used. After propensity score matching, the thiopental group showed a lower incidence of the postoperative neurological complications than non-thiopental group (5.5% vs. 17.1%, p = 0.001). In multivariate analysis, thiopental reduced the risk of postoperative neurological complications (odds ratio (OR) 0.26, 95% confidence interval (CI) 0.13 to 0.51, p < 0.001) while aneurysm size ≥ 10 mm (OR 4.48, 95% CI 1.69 to 11.87, p = 0.003), and hyperlipidemia (OR 2.24, 95% CI 1.16 to 4.32, p = 0.02) increased the risk of postoperative neurological complications. This study showed that thiopental was associated with the lower risk of neurological complications after clipping of UIA.

Interactions of antiepileptic drugs with drugs approved for the treatment of indications other than epilepsy

Introduction: Comorbidities of epilepsy may significantly interfere with its treatment as diseases in the general population are also encountered in epilepsy patients and some of them even more frequently (for instance, depression, anxiety, or heart disease). Obviously, some drugs approved for other than epilepsy indications can modify the anticonvulsant activity of antiepileptics. Areas covered: This review highlights the drug-drug interactions between antiepileptics and aminophylline, some antidepressant, antiarrhythmic (class I-IV), selected antihypertensive drugs and non-barbiturate injectable anesthetics (ketamine, propofol, etomidate, and alphaxalone). The data were reviewed mainly from experimental models of seizures. Whenever possible, clinical data were provided. PUBMED data base was the main search source.Expert opinion: Aminophylline generally reduced the protective activity of antiepileptics, which, to a certain degree, was consistent with scarce clinical data on methylxanthine derivatives and worse seizure control. The only antiarrhythmic with this profile of action was mexiletine when co-administered with VPA. Among antidepressants and non-barbiturate injectable anesthetics, trazodone, mianserin and etomidate or alphaxalone, respectively, negatively affected the anticonvulsant action of some antiepileptic drugs. Clinical data indicate that only amoxapine, bupropion, clomipramine and maprotiline should be used with caution. Possibly, drugs reducing the anticonvulsant potential of antiepileptics should be avoided in epilepsy patients.

Perioperative Management of Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage is an acute neurologic emergency. Prompt definitive treatment of the aneurysm by craniotomy and clipping or endovascular intervention with coils and/or stents is needed to prevent rebleeding. Extracranial manifestations of aneurysmal subarachnoid hemorrhage include cardiac dysfunction, neurogenic pulmonary edema, fluid and electrolyte imbalances, and hyperglycemia. Data on the impact of anesthesia on long-term neurologic outcomes of aneurysmal subarachnoid hemorrhage do not exist. Perioperative management should therefore focus on optimizing systemic physiology, facilitating timely definitive treatment, and selecting an anesthetic technique based on patient characteristics, severity of aneurysmal subarachnoid hemorrhage, and the planned intervention and monitoring. Anesthesiologists should be familiar with evoked potential monitoring, electroencephalographic burst suppression, temporary clipping, management of external ventricular drains, adenosine-induced cardiac standstill, and rapid ventricular pacing to effectively care for these patients.

Surgical Approaches to Basilar Apex Aneurysms: An Illustrative Review

Surgical management of basilar apex aneurysms remains one of the most challenging areas in neurovascular surgery. Technical demands of treating these aneurysms have inspired several generations of neurosurgeons to push the limitations of technical achievement. Advances in neuroanesthesia, cerebral protection paradigms, and critical care management have enhanced surgical outcomes of these lesions. Several approaches have been described to reach these lesions from anterolateral or lateral corridors. Each surgical approach has its own advantages and limitations and should be chosen for each patient according to the aneurysm's position, projection, parent arteries, and perforators. In this review, we will discuss pros and cons of the common approaches to these aneurysms with description of the important steps of each surgical procedure.

The 25th anniversary of the retrograde suction decompression technique (Dallas technique) for the surgical management of paraclinoid aneurysms: historical background, systematic review, and pooled analysis of the literature

OBJECTIVE

Paraclinoid internal carotid artery (ICA) aneurysms frequently require temporary occlusion to facilitate safe clipping. Brisk retrograde flow through the ophthalmic artery and cavernous ICA branches make simple trapping inadequate to soften the aneurysm. The retrograde suction decompression (RSD), or Dallas RSD, technique was described in 1990 in an attempt to overcome some of those treatment limitations. A frequent criticism of the RSD technique is an allegedly high risk of cervical ICA dissection. An endovascular modification was introduced in 1991 (endovascular RSD) but no studies have compared the 2 RSD variations.

METHODS

The authors performed a systematic review of MEDLINE/PubMed and Web of Science and identified all studies from 1990-2016 in which either Dallas RSD or endovascular RSD was used for treatment of paraclinoid aneurysms. A pooled analysis of the data was completed to identify important demographic and treatment-specific variables. The primary outcome measure was defined as successful aneurysm obliteration. Secondary outcome variables were divided into overall and RSD-specific morbidity and mortality rates.

RESULTS

Twenty-six RSD studies met the inclusion criteria (525 patients, 78.9% female). The mean patient age was 53.5 years. Most aneurysms were unruptured (56.6%) and giant (49%). The most common presentations were subarachnoid hemorrhage (43.6%) and vision changes (25.3%). The aneurysm obliteration rate was 95%. The mean temporary occlusion time was 12.7 minutes. Transient or permanent morbidity was seen in 19.9% of the patients. The RSD-specific complication rate was low (1.3%). The overall mortality rate was 4.2%, with 2 deaths (0.4%) attributable to the RSD technique itself. Good or fair outcome were reported in 90.7% of the patients.Aneurysm obliteration rates were similar in the 2 subgroups (Dallas RSD 94.3%, endovascular RSD 96.3%, p = 0.33). Despite a higher frequency of complex (giant or ruptured) aneurysms, Dallas RSD was associated with lower RSD-related morbidity (0.6% vs 2.9%, p = 0.03), compared with the endovascular RSD subgroup. There was a trend toward higher mortality in the endovascular RSD subgroup (6.4% vs 3.1%, p = 0.08). The proportion of patients with poor neurological outcome at last follow-up was significantly higher in the endovascular RSD group (15.4% vs 7.2%, p < 0.01).

CONCLUSIONS

The treatment of paraclinoid ICA aneurysms using the RSD technique is associated with high aneurysm obliteration rates, good long-term neurological outcome, and low RSD-related morbidity and mortality. Review of the RSD literature showed no evidence of a higher complication rate associated with the Dallas technique compared with similar endovascular methods. On a subgroup analysis of Dallas RSD and endovascular RSD, both groups achieved similar obliteration rates, but a lower RSD-related morbidity was seen in the Dallas technique subgroup. Twenty-five years after its initial publication, RSD remains a useful neurosurgical technique for the management of large and giant paraclinoid aneurysms.

Intraoperative Imaging for Vascular Lesions

Neurovascular surgery is a broad and challenging, yet exciting field within neurologic surgery. The neurovascular surgeon must be meticulous; because the brain and spinal cord are unforgiving to ischemic insults. Along with the pressures of this demanding subspecialty comes the potential to help patients recover from potentially devastating pathology to go on and lead normal, healthy lives. Several intraoperative imaging modalities are available to help maximize treatment success while reducing risk. This article reviews each of these modalities, including digital subtraction angiography, fluorescence angiography, Doppler ultrasonography, laser Doppler, laser speckle contrast imaging, neuronavigation, and neuroendoscopy.

Fluorescence in neurosurgery: Its diagnostic and therapeutic use. Review of the literature

Fluorescent agents, e.g. 5-aminolevulinic acid (5-ALA), fluorescein and indocyanine green (ICG) are in common use in neurosurgery for tumor resection and neurovascular surgery. Protoporphyrine IX (PPIX) as major metabolite of 5-ALA is a strong fluorescent substance accumulated within malignant glioma tissue and a very sensitive and specific tool for visualizing high grade glioma tissue during surgery. Furthermore, 5-ALA or rather PPIX also offers an intratumoral therapeutic option stimulated by laser light in specific wavelength. Fluorescein was demonstrated to show similar fluorescent reactions in neurosurgery, but is controversial in its use, especially in high grade tumor surgery. Intraoperative angiography during resection of arterio-venous malformations, extracranial-intracranial-bypass or aneurysm surgery is supported by ICG fluorescence. Generally ICG will provide beneficial information for both, exposure of the pathology and illustration of healthy structures. This manuscript shows an overview of the literature focussing fluorescence in neurosurgery.

Carotid endarterectomy without shunt: the role of cerebral metabolic protection

BACKGROUND

The optimal method to protect the brain from hemodynamic ischemia during carotid endarterectomy (CEA) remains controversial. This study reports our experience with induced arterial hypertension and selective etomidate cerebral protection in a cohort of patients who underwent CEA without shunting and continuous electroencephalography (EEG) monitoring.

METHODS

We reviewed retrospectively 102 consecutive CEAs performed in 102 patients with routine EEG monitoring and general anesthesia between March 1998 and October 2002. There were 65 (66%) symptomatic and 37 (34%) asymptomatic individuals. A protocol of induced arterial hypertension against EEG ischemic changes during carotid artery cross clamping was followed. Only patients with EEG changes refractory to induced hypertension went into etomidate-induced burst suppression.

RESULTS

EEG changes were classified as mild, moderate and severe. Twenty patients (19.6%) developed asymmetric EEG changes, of which the great majority were mild and moderate (75%, p< 0.05). Seven patients with moderate (n=3) and severe (n=4) EEG changes needed etomidate cerebral protection. There were no mortalities and only one stroke (0.98%) is reported in the series. The morbidity rate was 6.8% and included transient cranial nerve palsies (n=5) and wound hematoma (n=1).

CONCLUSIONS

Carotid endarterectomy can be safely performed with EEG monitoring and selective induced arterial hypertension and etomidate cerebral protection. Our results suggest that this method may be a good alternative for shunting and its inherent risks.

Intra operative indocyanine green video-angiography in cerebrovascular surgery: An overview with review of literature

Microscope integrated Near infra red Indocyanine green video angiography (NIR ICG VA) has been frequently used in cerebrovascular surgery. It is believed to be a simple and reliable method with acquisition of real time high spatial resolution images. The aim of this review article was to evaluate the efficacy of intra operative Indocyanine green video angiography (ICG VA) in Aneurysm, brain arteriovenous malformations (AVM) and extracranial-intracranial (EC-IC) bypass surgeries and also to analyze its limitations. Intra operative imaging is a very useful tool in guiding surgery; thus, avoiding surgical morbidity. Now-a-days, many cerebrovascular units are using ICG VA rather than Doppler and intra operative DSA in most of their aneurysm surgeries, and surgeons are incorporating this technique for AVM and in EC-IC bypass surgeries too. This article is an overview of the beneficial effects of ICG VA in cerebrovascular surgery and will also point out its limitations in various circumstances. Intra operative ICG VA gives high resolution, real time images of arterial, capillary, and venous flow of cerebral vasculature. Although it gives adequate information about the clipped neck, parent/branching artery and perforator involvement, it has some limitations like viewing the neck residuals located behind the aneurysm, thick walled atherosclerotic vessels, and thrombosed aneurysms. In AVM surgery, it is useful in detecting the residual nidus in diffuse type AVM, but cannot be relied in deep seated AVMs and it gives exact information about the anastomosis site in EC-IC bypass, thus, avoiding early bypass graft failure. NIR ICG VA is a simple, reliable, and quick method to pick up subtle findings in cerebrovascular procedures. But in selected cases of aneurysms, endoscopy and intra operative Digital substraction angiography (DSA) may be helpful, whereas in deep seated AVMs, navigation may be required as an adjunct to confirm intra operative findings.

Guidelines for the management of aneurysmal subarachnoid hemorrhage: a guideline for healthcare professionals from the American Heart Association/american Stroke Association

PURPOSE

The aim of this guideline is to present current and comprehensive recommendations for the diagnosis and treatment of aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

A formal literature search of MEDLINE (November 1, 2006, through May 1, 2010) was performed. Data were synthesized with the use of evidence tables. Writing group members met by teleconference to discuss data-derived recommendations. The American Heart Association Stroke Council's Levels of Evidence grading algorithm was used to grade each recommendation. The guideline draft was reviewed by 7 expert peer reviewers and by the members of the Stroke Council Leadership and Manuscript Oversight Committees. It is intended that this guideline be fully updated every 3 years.

RESULTS

Evidence-based guidelines are presented for the care of patients presenting with aSAH. The focus of the guideline was subdivided into incidence, risk factors, prevention, natural history and outcome, diagnosis, prevention of rebleeding, surgical and endovascular repair of ruptured aneurysms, systems of care, anesthetic management during repair, management of vasospasm and delayed cerebral ischemia, management of hydrocephalus, management of seizures, and management of medical complications.

CONCLUSIONS

aSAH is a serious medical condition in which outcome can be dramatically impacted by early, aggressive, expert care. The guidelines offer a framework for goal-directed treatment of the patient with aSAH.

Comparative Study of Brain Protection Effect between Thiopental and Etomidate Using Bispectral Index during Temporary Arterial Occlusion

OBJECTIVE

This study was conducted to compare the effect of etomidate with that of thiopental on brain protection during temporary vessel occlusion, which was measured by burst suppression rate (BSR) with the Bispectral Index (BIS) monitor.

METHODS

Temporary parent artery occlusion was performed in forty one patients during cerebral aneurysm surgery. They were randomly assigned to one of two groups. General anesthesia was induced and maintained with 1.5-2.5 vol% sevoflurane and 50% N(2)O. The pharmacological burst suppression (BS) was induced by a bolus injection of thiopental (5 mg/kg, group T) or etomidate (0.3 mg/kg, group E) according to randomization prior to surgery. After administration of drugs, the hemodynamic variables, the onset time of BS, the numerical values of BIS and BSR were recorded at every minutes.

RESULTS

There were no significant differences of the demographics, the BIS numbers and the hemodynamic variables prior to injection of drugs. The durations of burst suppression in group E (11.1±6.8 min) were not statistically different from that of group T (11.1±5.6 min) and nearly same pattern of burst suppression were shown in both groups. More phenylephrine was required to maintain normal blood pressure in the group T.

CONCLUSION

Thiopental and etomidate have same duration and a similar magnitude of burst suppression with conventional doses during temporary arterial occlusion. These findings suggest that additional administration of either drug is needed to ensure the BS when the temporary occlusion time exceed more than 11 minutes. Etomidate can be a safer substitute for thiopental in aneurysm surgery.

Retrograde trans-posterior communicating artery snare-assisted rescue of lost access to a foreshortened pipeline embolization device: complication management

BACKGROUND AND IMPORTANCE

The Pipeline embolization device (PED; Covidien Vascular Therapies, Mansfield, Massachusetts) is a promising, yet experimental, vascular reconstruction device for the treatment of complex intracranial aneurysms. We present a PED-related complication and describe a salvage strategy.

CLINICAL PRESENTATION

A 64-year-old woman underwent PED-assisted parent vessel reconstruction for her giant cavernous internal carotid artery (ICA) aneurysm. During placement of the first PED, the proximal part of the PED foreshortened and was displaced into the aneurysm sac. Multiple subsequent attempts to recatheterize the PED failed, and, ultimately, distal access through and beyond the PED was lost. Therefore, completion of the Pipeline construct by stacking PEDs for definitive treatment was prevented. Retrograde access of the PED was gained from the distal ICA through a microwire that was advanced from the basilar artery through the posterior communicating artery. The microwire from the distal ICA was grasped with a snare from the proximal ICA and pulled down to the cervical ICA. The opened snare around the microwire was used as a lasso to advance a microcatheter from the cervical ICA through the PED to regain distal access. Five more PEDs were used to achieve complete parent vessel reconstruction and aneurysm obliteration.

CONCLUSION

Maintaining distal access is critical until the entire parent vessel is reconstructed, especially when multiple PEDs are required. The salvage technique described may help regain distal access if it is lost during the procedure.

Emergent middle cerebral artery embolectomy: a useful technique for cranial base surgery

Given the poor natural history of untreated symptomatic acute middle cerebral artery occlusion, we have attempted emergent reperfusion in all three cases of acute embolic middle cerebral artery occlusion seen on our cranial base service over the last 10 years. One patient developed a massive stroke requiring a life-saving "strokectomy" within 48 hours, which left him permanently hemiplegic, hemianopic, and hemihypesthetic after a failed attempt at reperfusion by superselective endovascular injection of urokinase. The other two patients, who were aphasic and densely hemiparetic, underwent successful emergent embolectomy with reperfusion established within 5 and 12 hours, respectively. One of the two is now neurologically normal, and the second is left with a subtle monoparesis but is independent in activities of daily living. Since middle cerebral artery embolism in cranial base patients usually occurs in a closely monitored hospital setting, we are presented with a unique opportunity for early successful operative intervention. Principles for optimizing outcome include: early recognition and diagnosis, maximization of medical therapy during the diagnostic workup prior to embolectomy (induced hypertension, intravascular volume expansion, and pharmacologic cerebral metabolic demand reduction), confirmation that the involved region does not have absent blood flow by xenon/computed tomography, early operative intervention, and careful surgical technique.

Prospective Comparison of Intraoperative Vascular Monitoring Technologies During Cerebral Aneurysm Surgery

BACKGROUND:

Microscope integrated intraoperative near-infrared indocyanine green angiography (ICGA) provides assessment of the cerebral vasculature in the operating field.

OBJECTIVE:

To prospectively compare the value of ICGA-derived information during cerebral aneurysm surgery with data simultaneously generated from other intraoperative monitoring and vascular imaging techniques.

METHODS:

Data from 104 patients with 123 cerebral aneurysms who were operated on were prospectively recorded. Results of intraoperative vascular monitoring and descriptions of how this information influenced intraoperative decision making were analyzed.

RESULTS:

Clip repositioning was necessary in 30 of 123 aneurysms (24.4%) treated. Parent artery occlusion was documented by microvascular Doppler ultrasound in 4 aneurysms. ICGA disclosed parent artery stenoses not detected by sonography in 7 cases. Neuroendoscopy was used in 13 cases of midline aneurysms to confirm perforator patency after clipping, and disclosed aneurysm misclipping undetected by ICGA and digital subtraction angiography in 1 aneurysm. The information from DSA and ICGA corresponded in 120 of 123 aneurysms operated on (97.5 %). In 1 patient, ICGA underestimated a relevant parent artery stenosis detected by digital subtraction angiography. In 2 patients with relevant aneurysmal misclipping, digital subtraction angiography and ICGA led to conflicting results that could be clarified only when both methods were used and interpreted together.

CONCLUSION:

The intraoperative monitoring and vascular imaging methods compared were complementary rather than competitive in nature. None of the devices used were absolutely reliable when used as a stand-alone method. Correct intraoperative assessment of aneurysm occlusion, perforating artery patency, and parent artery reconstruction was possible in all patients when these techniques were used in combination.

Microscope integrated indocyanine green video-angiography in cerebrovascular surgery

Microscope integrated indocyanine green video-angiography (ICG-VA) is a new technique for intraoperative assessment of blood flow that has been recently applied to the field of Neurosurgery. ICG-VA is known as a simple and practical method of blood flow assessment with acceptable reliability. Real time information obtained under magnification of operating microscope has many potential applications in the microneurosurgical management of vascular lesions. This review is based on institutional experience with use of ICG-VA during surgery of intracranial aneurysms, AVMs and other vascular lesions at the Department of Neurosurgery at Helsinki University Central Hospital.

Intraoperative computed tomography angiography with computed tomography perfusion imaging in vascular neurosurgery: feasibility of a new concept

OBJECT

In vascular neurosurgery, there is a demand for intraoperative imaging of blood vessels as well as for rapid information about critical impairment of brain perfusion. This study was conducted to analyze the feasibility of intraoperative CT angiography and brain perfusion mapping using an up-to-date multislice CT scanner in a prospective pilot series.

METHODS

Ten patients with unruptured aneurysms underwent intraoperative scanning with a 40-slice sliding-gantry CT scanner. Multimodal CT acquisition was obtained in 8 patients consisting of dynamic perfusion CT (PCT) scanning followed by intracranial CT angiography. Two of these patients underwent CT angiography and PCT 2 times in 1 session as a control after repositioning cerebral aneurysm clips. In another 2 patients, CT angiography was performed alone. The quality of all imaging obtained was assessed in a blinded consensus reading performed by an experienced neurosurgeon and an experienced neuroradiologist. A 6-point scoring system ranging from excellent to insufficient was used for quality evaluation of PCT and CT angiography.

RESULTS

In 9 of 10 PCT data sets, the quality was rated excellent or good. In the remaining case, the quality was rated insufficient for diagnostic evaluation due to major streak artifacts induced by the titanium pins of the head clamp. In this particular case, the quality of the related CT angiography was rated good and sufficient for intraoperative decision making. The quality of all 12 CT angiography data sets was rated excellent or good. In 1 patient with an anterior communicating artery aneurysm, PCT scanning led to a repositioning of the clip because of an ischemic pattern of the perfusion parameter maps due to clip stenosis of an artery. The subsequent PCT scan obtained in this patient revealed an improved perfusion of the related vascular territory, and follow-up MR imaging showed only minor ischemia of the anterior cerebral artery territory.

CONCLUSIONS

Intraoperative CT angiography and PCT scanning were shown to be feasible with short acquisition time, little interference with the surgical workflow, and very good diagnostic imaging quality. Thus, these modalities might be very helpful in vascular neurosurgery. Having demonstrated their feasibility, the impact of these methods on patients' outcomes has now to be analyzed prospectively in a larger series.

Application of microscope integrated indocyanine green video-angiography during microneurosurgical treatment of intracranial aneurysms: a review

Indocyanine Green Video Angiography (ICG-VA) is recently introduced to the practice of cerebrovascular neurosurgery. This technique is safe and noninvasive and provides reliable real-time information on the patency of blood vessels of any size, as well as residual filling of aneurysms. In this article, a review of the literature and our experience with ICG-VA during microneurosurgery of intracranial aneurysms is presented.

Effects of propofol and etomidate on hydrogen peroxide-induced oxidative damage in hepatocyte

BACKGROUND

The present investigation was undertaken to evaluate the protective effect of propofol and etomidate against hydrogen peroxide (H2O2) induced oxidative damage in human hepatic SNU761 cells by measuring lactate dehydrogenase (LDH).

METHODS

The cell line of human hepatocellular carcinoma was grown for 24 hours in dissociated cell culture. They were divided into eight groups: negative control (NC) group with no drug administration, positive control (PC) group with H2O2 250 micrometer and other groups pretreated with propofol (P; 1, 10, 50 micrometer) or etomidate (ET; 1, 10, 50 micrometer) followed H2O2 administration. After 7 hours, cell death was assessed by morphology under the light microscope and quantified by measuring the LDH in the culture media.

RESULTS

In the light microscopic findings, the intact cells were increased in all three propofol groups compared to group PC. H2O2-induced LDH production was also significantly suppressed in all three propofol groups compared to group PC (P < 0.001). There were no significant differences in the microscopic findings and LDH production between the etomidate groups and group PC.

CONCLUSIONS

These results suggest that the propofol has protective effect on the hepatocyte against H2O2-induced oxidative stress.

Risk of stroke with temporary arterial occlusion in patients undergoing craniotomy for cerebral aneurysm

OBJECTIVE

This study was performed to elucidate the technical and patient-specific risk factors for postoperative ischemia in patients undergoing temporary arterial occlusion (TAO) during the surgical repair of their aneurysms.

METHODS

Eighty-nine consecutive patients in whom TAO was performed during surgical repair of an aneurysm were retrospectively analyzed. The demographics of the patients were analyzed with respect to age, Hunt and Hess grade on admission, Fisher grade of hemorrhage, aneurysm characteristics, timing of surgery, duration of temporary occlusion, and number of temporary occlusive episodes. Outcome was analyzed at the 3-month follow-up, along with the occurrence of symptomatic and radiological stroke.

RESULTS

In overall, twenty-seven patients (29.3%) had radiologic ischemia attributable to TAO and fifteen patients (16.3%) had symptomatic ischemia attributable to TAO. Older age and poor clinical grade were associated with poor clinical outcome. There was a significantly higher rate of symptomatic ischemia in patients who underwent early surgery (p = 0.007). The incidence of ischemia was significantly higher in patients with TAO longer than 10 minutes (p = 0.01). In addition, patients who underwent repeated TAO, which allowed reperfusion, had a lower incidence of ischemia than those who underwent single TAO lasting for more than 10 minutes (p = 0.011).

CONCLUSION

Duration of occlusion is the only variable that needs to be considered when assessing the risk of postoperative ischemic complication in patients who undergo temporary vascular occlusion. Attention must be paid to the patient's age, grade of hemorrhage, and the timing of surgery. In addition, patients undergoing dissection when brief periods of temporary occlusion are performed may benefit more from intermittent reperfusion than continuous clip application. With careful planning, the use of TAO is a safe technique when used for periods of less than 10 minutes.

Microscope-integrated near-infrared indocyanine green videoangiography during surgery of intracranial aneurysms: the Helsinki experience

BACKGROUND

Microscope-integrated near-infrared indocyanine green videoangiography (ICG-VA) is a new method of intraoperative blood flow assessment. The objective of this study was to evaluate the reliability of this technique in the evaluation of neck residuals and patency of branches after microneurosurgical clipping of intracranial aneurysms (IAs).

METHODS

During a period of 14 months, between November 2005 and December 2006, 289 patients with intracranial aneurysms were operated on in our institution. Intraoperative ICG-VA was performed during microneurosurgical clipping of 239 IAs in 190 patients. Postoperative computed tomography and computed tomography angiography (CTA) were performed for all patients. Intraoperative interpretation of ICG-VA in assessing the neck residual or the patency of vessels after clipping of each single aneurysm were recorded and correlated with postoperative CTA and/or digital subtraction angiography.

RESULTS

Postoperative imaging studies revealed no incomplete occlusions of aneurysm domes. Unexpected neck residuals were observed in 14 aneurysms (6%). There were no parent artery occlusions. Unexpected branch occlusions including both major and minor branching arteries were observed in 15 aneurysms (6%).

CONCLUSIONS

Indocyanine green videoangiograph is a simple and fast method of blood flow assessment with acceptable reliability. Indocyanine green videoangiograph can provide real-time information to assess blood flow in vessels of different size as well as the occlusion of the aneurysm. Intraoperative assessment of blood flow in the perforating branches is one of the most important advantages. In selected cases such as giant, complex, and deep-sited aneurysms or when the quality of image in ICG-VA is not adequate, other methods of intraoperative blood flow assessment should be considered.

The mechanisms of the direct action of etomidate on vascular reactivity in rat mesenteric resistance arteries

BACKGROUND

Etomidate minimally influences hemodynamics at a standard induction dose in young healthy patients, but can cause significant systemic hypotension at higher doses for induction or electroencephalographic burst suppression (i.e., cerebral protection) in patients with advanced age or heart disease, and during cardiopulmonary bypass. However, less is known about its action on systemic resistance arteries.

METHODS

Using an isometric force recording method and fura-2-fluorometry, we investigated the action of etomidate on vascular reactivity in small mesenteric arteries from young (7-8 wk old, n = 179) and aged (96-98 wk old, n = 10) rats.

RESULTS

In the endothelium-intact strips from young rats, etomidate enhanced the contractile response to norepinephrine or KCl (40 mM) at 3 microM but inhibited it at higher concentrations (>or=10 microM). The enhancement was still observed after treatment with N(G)-nitro l-arginine, tetraethylammonium, diclofenac, nordihydroguaiaretic acid, losartan, ketanserin, BQ-123, or BQ-788, but was not observed in aged rats. In the endothelium-denuded strips from young rats, etomidate (>or=10 microM) consistently inhibited the contractile response to norepinephrine or KCl without enhancement at 3 microM. In the fura-2-loaded, endothelium-denuded strips from young rats, etomidate inhibited norepinephrine- or KCl-induced increases in both intracellular Ca(2+) concentration ([Ca(2+)]i) and force. Etomidate still inhibited the norepinephrine-induced increase in [Ca(2+)]i after depletion of the intracellular Ca(2+) stores by ryanodine, which was sensitive to nifedipine. Etomidate had little effect on norepinephrine- or caffeine-induced Ca(2+) release from the intracellular stores or Ca(2+) uptake into the intracellular stores. During stimulation with norepinephrine or KCl, etomidate had little effect on the [Ca(2+)]i-force relation at low concentrations (<or=30 microM) but caused its downward shift at 100 microM.

CONCLUSIONS

In small mesenteric arteries, etomidate influences the contractile response to norepinephrine or membrane depolarization through endothelium-dependent enhancing and endothelium-independent inhibitory actions. The enhancement is at least in part independent of nitric oxide, endothelium-derived hyperpolarizing factor, cyclooxygenase products, lipoxygenase products, angiotensin II, serotonin, or endothelin-1, but may involve some signaling pathway that is impaired by aging. The endothelium-independent inhibition is due to decreases in both the [Ca(2+)]i and myofilament Ca(2+) sensitivity in vascular smooth muscle cells. The decrease in [Ca(2+)]i would be due mainly to inhibition of voltage-gated Ca(2+) influx. The observed inability of lower concentrations (1-3 microM) of etomidate to cause significant vasodilation is consistent with minimal changes in hemodynamics during induction of anesthesia with etomidate in young subjects, whereas the observed vasodilator action of higher concentrations of etomidate might underlie systemic hypotension caused by higher doses of etomidate in the clinical setting.

Impact of anesthetic agents on cerebrovascular physiology in children

The role of the pediatric neuroanesthetist is to provide comprehensive care to children with neurologic pathologies. The cerebral physiology is influenced by the developmental stage of the child. The understanding of the effects of anesthetic agents on the physiology of cerebral vasculature in the pediatric population has significantly increased in the past decade allowing a more rationale decision making in anesthesia management. Although no single anesthetic technique can be recommended, sound knowledge of the principles of cerebral physiology and anesthetic neuropharmacology will facilitate the care of pediatric neurosurgical patients.

Clinical and angiographic outcome after endovascular management of giant intracranial aneurysms

OBJECTIVE

Giant (>or=25 mm) intracranial aneurysms (IA) have an extremely poor natural history and continue to confound modern techniques for management. Currently, there is a dearth of large series examining endovascular treatment of giant IAs only.

METHODS

We reviewed long-term clinical and radiological outcome from a series of 39 consecutive giant IAs treated with endovascular repair in 38 patients at 2 tertiary referral centers. Data were evaluated in 3 ways: on a per-treatment session basis for each aneurysm, at 30 days after each patient's final treatment, and at the last known follow-up examination.

RESULTS

Ten (26%) aneurysms were ruptured. At the last angiographic follow-up examination (21.5 +/- 22.9 months), 95% or higher and 100% occlusion rates were documented in 64 and 36% of aneurysms, respectively, with parent vessel preservation maintained in 74%. Stents were required in 25 aneurysms. Twenty percent of treatment sessions resulted in permanent morbidity, and death within 30 days occurred after 8% of treatment sessions. On average, 1.9 +/- 1.1 sessions were required to treat each aneurysm, with a resulting cumulative per-patient mortality of 16% and morbidity of 32%. At the last known clinical follow-up examination (mean, 24.8 +/- 24.8 months), 24 (63%) patients had Glasgow Outcome Scale scores of 4 or 5 ("good" or "excellent"), 10 patients had worsened neurological function from baseline (26% morbidity), and 11 had died (29% mortality).

CONCLUSION

We present what is to our knowledge the largest series to date evaluating outcome after consecutive giant IAs treated with endovascular repair. Giant IAs carry a high risk for surgical or endovascular intervention. We hope critical and honest evaluation of treatment results will ensure continued improvement in patient care.

Hyperosmolar, increased-anion-gap metabolic acidosis and hyperglycemia after etomidate infusion

Hyperosmolar increased-anion-gap metabolic acidosis without hyperglycemia has been reported after infusions of etomidate and other medications containing propylene glycol. We report a case of this biochemical abnormality with severe hyperglycemia. Cessation of the etomidate infusion along with other supportive measures resulted in prompt resolution of the metabolic acidosis and hyperglycemia.

The Use of the Excimer Laser-assisted Anastomosis Technique Alleviates Neuroanesthesia During Cerebral High-flow Revascularization

In patients with complex intracranial aneurysms or skull base tumors, parent vessel occlusion and flow replacement by high-flow bypass surgery is a demanding therapy, both for the neurosurgeon and the neuroanesthesiologist. One reason for this is the need for prolonged temporary occlusion of a major cerebral artery, which carries a high risk of perioperative ischemia and necessitates versatile neuroprotective measures during anesthesia. Recently, a novel excimer laser-assisted nonocclusive anastomosis (ELANA) technique has been introduced, circumventing the need for temporary occlusion of cerebral vessels. We hypothesized that the use of this ELANA technique would facilitate also the neuroanesthesiologic management of these patients. To test this, we reviewed the details of the neuroanesthesiologic management of patients undergoing ELANA high-flow bypass surgery at our institution. Twenty-nine patients with giant aneurysms (n=27) or skull base tumor (n=2) who were undergoing parent vessel occlusion and permanent flow replacement by high-flow bypass surgery using the ELANA technique were investigated retrospectively. The records of the patients were analyzed for induction and maintenance of anesthesia, fluid therapy, transfusion requirements, hemodynamic parameters, and brain protective strategies. Although we are not able to provide a sufficient body of cohort data to compare the neuroanesthesiologic management of patients undergoing the conventional anastomosis technique with management using the ELANA technique, in each of our reported cases the conventional anastomosis technique would have entailed a high probability of prolonged temporary occlusion that would, in turn, have warranted intensive brain-protective strategies. The observation that use of the ELANA technique precluded the necessity of brain-protective strategies without entailing perioperative cerebral infarction suggests that the ELANA technique supports the neurosurgeon in creating difficult permanent intracranial anastomoses and also facilitates neuroanesthesiologic management of patients undergoing cerebral high-flow revascularization procedures.

Cerebral protection

Ischaemic/hypoxic insults to the brain during surgery and anaesthesia can result in long-term disability or death. Advances in resuscitation science encourage progress in clinical management of these problems. However, current practice remains largely founded on extrapolation from animal studies and limited clinical investigation. A major step was made with demonstration that rapid induction of mild sustained hypothermia in comatose survivors of out-of-hospital ventricular fibrillation cardiac arrest reduces death and neurological morbidity with negligible adverse events. This provides the first irrefutable evidence that outcome can be favourably altered in humans with widely applicable neuroprotection protocols. How far hypothermic protection can be extended to global ischaemia of other aetiologies remains to be determined. All available evidence suggests an adverse response to hyperthermia in ischaemic or post-ischaemic brain. Management of other physiological values can have dramatic effects in experimental injury models and this is largely supported by available clinical data. Hyperoxaemia may be beneficial in transient focal ischaemia but deleterious in global ischaemia. Hyperglycaemia causes exacerbation of most forms of cerebral ischaemia and this can be abated by restoration of normoglycaemia. Studies indicate little, if any, role for hyperventilation. There is little evidence in humans that pharmacological intervention is advantageous. Anaesthetics consistently and meaningfully improve outcome from experimental cerebral ischaemia, but only if present during the ischaemic insult. Emerging experimental data portend clinical breakthroughs in neuroprotection. In the interim, organized large-scale clinical trials could serve to better define limitations and efficacy of already available methods of intervention, aimed primarily at regulation of physiological homeostasis.

Effects of intraoperative hypothermia on neuropsychological outcomes after intracranial aneurysm surgery

OBJECTIVE

Subarachnoid hemorrhage and surgical obliteration of ruptured intracranial aneurysms are frequently associated with neurological and neuropsychological abnormalities. We reported that intraoperative cooling did not improve neurological outcome in good-grade surgical subarachnoid hemorrhage patients, as assessed by the Glasgow Outcome Scale score or other neurological and functional measures (National Institutes of Health Stroke Scale, Rankin Disability Scale, Barthel Activities of Daily Living). We now report the results of neuropsychological testing in these patients.

METHODS

A total of 1,001 patients who bled < or = 14 days before surgery were randomly assigned to intraoperative hypothermia (t = 33 degrees C) or normothermia (37 degrees C). Outcome was assessed approximately 3 months after surgery. Patients underwent the Benton Visual Retention, Controlled Oral Word Association, Rey-Osterrieth Complex Figure, Grooved Pegboard, and the Trail Making tests. T-scores for each test were calculated from normative data. T-scores were averaged to calculate a Composite Score. A test result (or the Composite Score) was considered "impaired" if the T-score was two or more standard deviations below the norm. A Mini-Mental State Examination was also performed.

RESULTS

Neurological outcome data were available in 1,000 patients. Sixty-one patients died. Of the 939 survivors, 873 completed 3 or more tests (exclusive of the Mini-Mental State Examination). Patients with poor neurological outcomes were less likely to complete testing; only 3.9% of Good Outcome (Glasgow Outcome Scale score = 1) patients were untested, compared with 38.6% of patients with Glasgow Outcome Scale scores of 3 and 4. There were no prerandomization demographic differences between the two treatment groups. For hypothermic patients, 16.8% were impaired from their Composite Score versus 20.0% of patients in the normothermic group (p = 0.317). For patients in the hypothermic group, 54.5% were impaired on at least one test, compared with 55.5% of patients in the normothermic group (p = 0.865). Similar results were seen in patients with baseline WFNS scores = I. Mini-Mental State Examination scores in the hypothermic and normothermic groups were 27.4 +/- 3.8 and 26.8 +/- 4.5, respectively.

INTERPRETATION

This is the largest prospective evaluation of neuropsychological function after subarachnoid hemorrhage to date. Testing was completed in a high fraction of patients, demonstrating the feasibility of such testing in a large trial. However, the frequent inability to complete testing in poor-outcome patients suggests that testing may be best used to refine outcome assessments in good-grade patients. Many patients showed impairment on at least one test, with global impairment present in 17 to 20% of patients (18-21% of survivors). This was true even among the patients with the best preoperative condition (WFNS = 1). There was no difference in the incidence of impairment between hypothermic and normothermic groups.

Retrograde suction decompression of giant paraclinoid aneurysms using a No. 7 French balloon–containing guide catheter

✓ The treatment of large and giant paraclinoid carotid artery (CA) aneurysms often requires the use of suction decompression for safe and effective occlusion. Both open and endovascular suction decompression techniques have been described previously. In this article the authors describe a revised endovascular suction decompression technique that provides several advantages in the treatment of large and giant paraclinoid and CA aneurysms.

A 51-year-old woman presented with a relatively brief history of progressive visual loss in the right eye, nonspecific headache, and an afferent pupillary defect. After angiography studies had been obtained, it was determined that she had a giant right paraclinoid internal CA aneurysm with a dome size of approximately 26 mm on the right and a neck diameter of 10 mm.

A modified technique was performed in which suction decompression was used. With the aid of a No. 7 French Concentric balloon guide catheter (Concentric Medical, Inc., Mountain View, CA) and application of a temporary clip distal to the aneurysm, the aneurysm was trapped and decompressed using retrograde suction through the guide catheter when the balloon was inflated. After satisfactory placement of three permanent clips, an intraoperative angiogram obtained through the same guide catheter confirmed CA patency. The aneurysm was then punctured and aspirated, ensuring complete occlusion of the aneurysm sac and reconstruction of the parent vessel. The patient made an excellent recovery and did not suffer any complications. She did not experience worsening in her vision.

This technical modification to endovascular suction decompression allows several potential advantages, including higher volume decompression and the ability to deliver endovascular devices to distal arterial locations.

Prospective evaluation of surgical microscope—integrated intraoperative near-infrared indocyanine green videoangiography during aneurysm surgery

Object. The authors prospectively compared a new technique of surgical microscope-based indocyanine green (ICG) videoangiography with intraoperative or postoperative digital subtraction (DS) angiography.

Method. The technique was performed during 187 surgical procedures in which 124 aneurysms in 114 patients were clipped. Using a newly developed setup, the ICG technique has been integrated into an operating microscope (Carl Zeiss Co., Oberkochen, Germany). A microscope-integrated light source containing infrared excitation light illuminates the operating field. The dye is injected intravenously into the patient, and intravascular fluorescence from within the blood vessels is imaged using a video camera attached to the microscope. The patency of parent, branching, and perforating arteries and documentation of clip occlusion of the aneurysm as shown by ICG videoangiography were compared with intraoperative or postoperative findings on DS angiography.

The results of ICG videoangiography corresponded with intra- or postoperative DS angiography in 90% of cases. The ICG technique missed mild but hemodynamically irrelevant stenosis that was evident on DS angiography in 7.3% of cases. The ICG technique missed angiographically relevant findings in three cases (one hemodynamically relevant stenosis and two residual aneurysm necks [2.7% of cases]). In two cases the missed findings were clinically and surgically inconsequential; in the third case, a 4-mm residual neck may require a second procedure. Indocyanine green videoangiography provided significant information for the surgeon in 9% of cases, most of which led to clip correction.

Conclusions. Microscope-based ICG videoangiography is simple and provides real-time information about the patency of vessels of all sizes and about the aneurysm sac. This technique may be useful during routine aneurysm surgery as an independent form of angiography or as an adjunct to intra- or postoperative DS angiography.

Experience from "double-insurance bypass." Surgical results and additional techniques to achieve complex aneurysm surgery in a safer manner

BACKGROUND

"Double-insurance bypass" was recently advocated to avoid the risk of cerebral ischemia during prolonged temporary occlusion of the carotid artery. For large aneurysms needing temporary but prolonged obliteration of the internal carotid artery (ICA). We have attempted the double-insurance bypass in 15 patients and, herein, report the efficacies and limitations of the procedure, and surgical techniques to make this procedure safer.

METHODS

We treated 15 patients with complex internal carotid aneurysms by clipping surgery with the aid of radial artery (RA) to proximal middle cerebral artery (MCA) bypass, so-called double-insurance bypass. We analyzed surgical results of the procedure.

RESULTS

In 11 patients, the duration of temporary occlusion of the ICA could be prolonged for as long as 110 minutes (mean, 45 minutes) without any ischemic complications. One patient in the earlier period of our experience suffered extended cerebral infarction due to possible restricted blood flow through the RA, because the brachial artery was compressed by the firm shoulder joint and neighboring structures. Thereafter, we routinely monitored the blood pressure of MCA (MCABP) and never experienced such cortical infarctions. Another 3 patients, however, experienced ischemia in the territory of perforating arteries that originated from a segment that could not be perfused by the RA-MCA bypass.

CONCLUSIONS

In combination with monitoring of MCABP, the double-insurance bypass can be a safer and more potent adjunctive procedure for the treatment of complex internal carotid aneurysms which require prolonged temporary occlusion of the ICA.

Clampage vasculaire temporaire

In many situations, temporary artery occlusion is an integral component of aneurysm surgery. The use of temporary clip may allow safer and easier aneurysmal dissection and clipping. Several points, concerning the duration and overall risks of temporary occlusion and the method of choice for cerebral function monitoring have to be discussed.

MATERIAL AND METHODS

Non exhaustive review of neurosurgical literature.

DISCUSSION

Temporary clip application decreases the risk of intraoperative aneurysmal rupture. The analysis of data published in the literature showed that several questions remain open concerning the optimal method of neuroprotection and cerebral function monitoring, as well as the limit of occlusion duration. Other clinical trials are needed to assess the efficacy and safety of this technique.

Mild intraoperative hypothermia during surgery for intracranial aneurysm

BACKGROUND

Surgery for intracranial aneurysm often results in postoperative neurologic deficits. We conducted a randomized trial at 30 centers to determine whether intraoperative cooling during open craniotomy would improve the outcome among patients with acute aneurysmal subarachnoid hemorrhage.

METHODS

A total of 1001 patients with a preoperative World Federation of Neurological Surgeons score of I, II, or III ("good-grade patients"), who had had a subarachnoid hemorrhage no more than 14 days before planned surgical aneurysm clipping, were randomly assigned to intraoperative hypothermia (target temperature, 33 degrees C, with the use of surface cooling techniques) or normothermia (target temperature, 36.5 degrees C). Patients were followed closely postoperatively and examined approximately 90 days after surgery, at which time a Glasgow Outcome Score was assigned.

RESULTS

There were no significant differences between the group assigned to intraoperative hypothermia and the group assigned to normothermia in the duration of stay in the intensive care unit, the total length of hospitalization, the rates of death at follow-up (6 percent in both groups), or the destination at discharge (home or another hospital, among surviving patients). At the final follow-up, 329 of 499 patients in the hypothermia group had a Glasgow Outcome Score of 1 (good outcome), as compared with 314 of 501 patients in the normothermia group (66 percent vs. 63 percent; odds ratio, 1.14; 95 percent confidence interval, 0.88 to 1.48; P=0.32). Postoperative bacteremia was more common in the hypothermia group than in the normothermia group (5 percent vs. 3 percent, P=0.05).

CONCLUSIONS

Intraoperative hypothermia did not improve the neurologic outcome after craniotomy among good-grade patients with aneurysmal subarachnoid hemorrhage.

Interactions between non-barbiturate injectable anesthetics and conventional antiepileptic drugs in the maximal electroshock test in mice--an isobolographic analysis

The aim of this study was the isobolographic evaluation of interactions between three non-barbiturate intravenous anesthetics and conventional antiepileptic drugs in the maximal electroshock-induced seizures in mice. Electroconvulsions were produced by means of an alternating current (ear-clip electrodes, 0.2-s stimulus duration, tonic hindlimb extension taken as the endpoint). Adverse effects were evaluated in the chimney test (motor performance) and passive avoidance task (long-term memory). Plasma levels of antiepileptic drugs were measured by immunofluorescence. Obtained results indicate that ketamine acts synergistically with valproate and carbamazepine. Also the combinations of propofol and valproate or phenobarbital led to synergistic interactions. An antagonism was found between etomidate and carbamazepine or phenobarbital. On the other hand, interactions between diphenylhydantoin and injectable anesthetics proved to be additive. The only exception was the combination of diphenylhydantoin and propofol (1:3). Pharmacokinetic phenomena do not seem to interfere with the observed interactions, since none of anesthetics influenced the free plasma concentrations of antiepileptic drugs. Referring to undesired effects, only propofol impaired long-term memory. Although propofol did not disturbed motor coordination, it enhanced motor impairment caused by carbamazepine and diphenylhydantoin. Results of the present study suggest that etomidate needs to be avoided in epileptic patients due to a possibility of negative interactions with some antiepileptic drugs and seizure precipitation.

Intraoperative Cerebral Angiography: Superficial Temporal Artery Method and Results

OBJECTIVE

To report the method for and results of intraoperative cerebral angiography performed via the superficial temporal artery, for assessment of cerebral aneurysm surgery.

METHODS

All patients undergoing craniotomies for treatment of intracranial aneurysms were prospectively entered into a database. A policy of performing angiography via the superficial temporal artery in appropriate cases was instituted. This procedure was performed with retrograde catheterization of the superficial temporal artery, as it coursed over the zygomatic arch, with an 18-gauge, 1.88-inch, intravenous catheter and hand injection of contrast material, with intraoperative digital subtraction fluoroscopic guidance.

RESULTS

Thirty-six patients who underwent 38 craniotomies for clipping of 43 aneurysms underwent intraoperative angiography via the superficial temporal artery. There were six unexpected findings (14%), including four unexpected arterial occlusions and two unexpected residual aneurysms. One aneurysm was observed to be patent when it was punctured, after intraoperative angiography had indicated no filling of the aneurysm. Additional clips were placed. Three patients (8%) developed multiple arterial infarctions in the territory of the injected carotid artery, for which multiple causes were possible. Adequate angiographic images could usually be obtained with this method.

CONCLUSION

Intraoperative angiography via the superficial temporal artery is simple and is not associated with substantial complications. It is a reasonable alternative to transfemoral angiography for detection of adverse consequences of intracranial aneurysm clipping.

Effects of etomidate, ketamine or propofol, and their combinations with conventional antiepileptic drugs on amygdala-kindled convulsions in rats

Ketamine, etomidate and propofol modified behavioral and electrographic correlates of kindled seizures in rats. In detail, ketamine (5 mg/kg) and propofol (15 mg/kg) significantly increased afterdischarge threshold, reduced seizure severity and shortened seizure and afterdischarge durations. Etomidate (7.5 mg/kg) was effective in terms of seizure and afterdischarge durations. Moreover, the combinations of ketamine (2.5 mg/kg) with carbamazepine (15 mg/kg) or valproate (50 mg/kg; all drugs at their subeffective doses), reduced the severity and duration of kindled seizures. The antiseizure potency of the ketamine/carbamazepine combination was comparable to that of carbamazepine alone administered at 20 mg/kg, while the effect of ketamine/valproate was comparable to the efficacy of valproate alone at 100 mg/kg. However, the combinations of ketamine with phenobarbital or diphenylhydantoin did not exert any protective action. Propofol and etomidate entirely failed to interact with conventional antiepileptics. The combinations of ketamine with carbamazepine or valproate did not induce any significant motor impairment in the chimney test or memory deficit in the passive avoidance task. A pharmacokinetic interaction, at least in plasma, can be excluded, because ketamine (2.5 mg/kg) did not affect the free plasma concentrations of carbamazepine or valproate. Results of the present study may suggest that there may be no risk of negative interactions between injectable anesthetics and antiepileptics in cases of partial epilepsy.

Surgical management of unruptured posterior carotid artery wall aneurysms

Intracranial aneurysms arising from the posterior wall of the supraclinoid carotid artery are extremely common lesions. The aneurysm dilation typically occurs in immediate proximity to the origin of the posterior communicating artery and, less commonly, the anterior choroidal artery (AChA). Because of the increasingly widespread use of noninvasive neuroimaging methods to evaluate patients believed to harbor cerebral lesions, many of these carotid artery aneurysms are now documented in their unruptured state, prior to occurrence of subarachnoid hemorrhage. Based on these factors, the management of unruptured posterior carotid artery (PCA) wall aneurysms is an important element of any neurosurgical practice. Despite impressive recent advances in endovascular therapy, the placement of microsurgical clips to exclude aneurysms with preservation of all afferent and efferent vasculature remains the most efficacious and durable therapy. To date, an optimal outcome is only achieved when the neurosurgeon is able to combine systematic preoperative neurovascular assessment with meticulous operative technique. In this report, the authors review their surgical approach to PCA wall aneurysms, which is greatly based on the extensive neurovascular experience of the senior author. Focus is placed on their methods of preoperative evaluation and operative technique, with emphasis on neurovascular anatomy and the significance of oculomotor nerve compression. They conclude by discussing surgery-related complications, with a particular focus on intraoperative rupture of aneurysms and their management, and the postoperative ischemic AChA syndrome.

[Giant supratentorial intracranial aneurysms. Analysis of 22 cases]

INTRODUCTION

Giant intracranial aneurysms represent 2 to 5% of all aneurysms. They are well characterized from the anatomical and clinical point of view. Their natural history shows its potential lethality. Surgical treatment of giant aneurysms is a challenge for neurosurgeons.

MATERIAL AND METHODS

Twenty-two patients were operated on through pterional craniotomy, specialized neuroanesthesia and microneurosurgical technics. Auxiliary methods like transitory clipping and retrograde decompression-suction technique were applied. Patients were followed at intensive care units and they were evaluated three months after the operation. Nineteen patients were in the fourth and sixth decade of life. Seventeen were females. Aneurysms were located at middle cerebral artery bifurcation; paraclinoidal carotid artery; proximal anterior cerebral artery and carotid bifurcation. Ninety one percent of aneurysms were clipped. Retrograde decompression-suction technique was performed in thirteen cases.

RESULTS

Seventeen patients had good outcome and one patient died (4.5%). There were 6 postoperative complications and in four disappeared three months later.

CONCLUSIONS

Giant aneurysms were operated on following main neurosurgical rules helped by auxiliar procedures to reduce aneurysms size and wall, aneurysms tension. New knowledge about giants aneurysms and the development of new techniques will permit better results.

Near-infrared indocyanine green video angiography: a new method for intraoperative assessment of vascular flow

OBJECTIVE

We report our initial clinical experience with a new method for intraoperative blood flow assessment. The purposes of the study were to assess the use of indocyanine green (ICG) video angiography in neurovascular cases, to assess the handling and image quality, to compare the findings with postoperative angiographic results, and to evaluate the clinical value of the method in a preliminary feasibility study.

METHODS

Fourteen patients with aneurysms (n = 12) or spinal (n = 1) or intracranial (n = 1) dural fistulae were included. Before and/or after aneurysm or dural fistula occlusion, ICG (25 mg) was injected intravenously. A near-infrared laser excitation light source (lambda = 780 nm) illuminated the operating field. The intravascular fluorescence of ICG (maximal lambda = 835 nm) was recorded by a nonintensified video camera, with optical filtering to block ambient and laser light for collection of only ICG-induced fluorescence.

RESULTS

A total of 21 investigations were performed for 14 patients. For the 17 successful ICG video angiographic investigations, image quality and resolution were excellent, allowing intraoperative real-time assessment of the cerebral circulation. ICG angiographic results could be divided into arterial, capillary, and venous phases, comparable to those observed with digital subtraction angiography. In all cases, the postoperative angiographic results corresponded to the intraoperative ICG video angiographic findings. In three cases, the information provided by intraoperative ICG angiography significantly changed the surgical procedure.

CONCLUSION

ICG video angiography is simple and provides real-time information on the patency of arterial and venous vessels of all relevant diameters, including small and perforating arteries (<0.5 mm), and the visible aneurysm sac. It may be a useful adjunct to improve the quality of neurovascular procedures and to document the intraoperative vascular flow.