The safety and efficiency of SMART coil for brain aneurysm: A systematic review and meta-analysis

BACKGROUND

The SMART coil system is a relatively new generation of embolic coils consisting of a bare platinum coil, a detachment pusher, and a detachment handle. This study investigated the safety and efficiency of the SMART coil system in treating cerebral aneurysms.

METHOD

PubMed/Medline, Embase, Web of Science, and Scopus were searched until October, 1st 2023. Non-English language, non-human studies, and non-original studies were excluded.

RESULTS

A total of 7 studies were included. The results of our study reflected complete aneurysm occlusion (mRRC1) rate of 45% (95% CI, 0.35-0.56), neck remnant aneurysm (mRRC2) rate of 36% (95% CI, 0.30-0.42), and residual aneurysm (mRRC3) rate of 22% (95% CI, 0.12-0.38) during post-procedural assessment. Moreover, considering longest follow-up, our study showed complete aneurysm occlusion (mRRC1) rate of 66% (95% CI, 0.43-0.84), neck remnant aneurysm (mRRC2) rate of 27% (95% CI, 0.13-0.49), and residual aneurysm (mRRC3) rate of 9% (95% CI, 0.04-0.20). In addition, recanalization and retreatment rates were reported 10% (95% CI, 0.06-0.17) and 9% (95% CI, 0.06-0.12), respectively. The rates of adverse and serious adverse events were 9% (95% CI, 0.07-0.10) and 6% (95% CI, 0.01-0.22), respectively. Three studies reported a stroke rate which was 2% (95% CI, 0.00-0.13), and five studies reported a mortality rate which was 6% (95% CI, 0.03-0.11).

CONCLUSION

The findings suggested that the SMART coil can be a safe and efficient treatment in patients with intracranial aneurysms compared to other available treatment methods.

Modified balloon-assisted coiling instead of acute stenting in the treatment of ruptured wide necked intracranial aneurysms

BACKGROUND

The aim of this study was to investigate the safety and efficiency of the modified balloon assisted coiling (mBAC) technique in endovascular treatment (EVT) of ruptured wide-necked aneurysms (WNAs) to avoid stent placement in the acute phase of subarachnoid hemorrhage (SAH).

METHODS

The local neurointerventional radiology database was retrospectively reviewed to identify patients who underwent EVT due to ruptured WNAs by the authors. According to the EVT technique performed, the study sample was divided into 3 groups: conventional BAC, stent assisted coiling (SAC), and mBAC. The patient demographics, aneurysm features, technical and clinical complications, aneurysm occlusion grades, morbidity, and mortality rates were comparatively analyzed.

RESULTS

This study involved a total of 113 patients who had ruptured WNAs. The mBAC technique was performed on 26 aneurysms (23 saccular and 3 fusiform) in 26 patients to avoid acute phase stenting. The mean continuous balloon inflation time was 7.1 ± 2.12 min. The initial and follow-up angiographic and clinical outcomes were better in the mBAC group than in the SAC group (p < 0.05).

CONCLUSIONS

The mBAC technique offers a prolonged, continuous balloon inflation time during the whole coiling process in the treatment of ruptured WNAs. The mBAC technique has the potential to obviate the need for SAC in patients who are candidates for stenting during the acute phase of SAH, and it might be considered a safe and effective endovascular approach with low complication rates and good angiographic and clinical outcomes.

The Morphology of Somatosensory Evoked Potentials During Middle Cerebral Artery Aneurysm Clipping (MoSAC): A Pilot Study

Somatosensory evoked potential (SEP) monitoring is a standard tool during clipping of aneurysms of the middle cerebral artery (MCA), and the parameter used to detect a state of cortical ischemia is amplitude. We think that the sensitivity of SEP can however be improved by using other parameters. Our study moves in this direction via SEP morphology. In this pilot preliminary study, involving a small sample without postoperative neurological deficit, we aimed at investigating the value of SEP morphology (in the 15- to 35-ms time frame), in comparison with SEP amplitude (N20 peak-to-peak), as a measure of sensitivity to blood flow reduction. The changes in the SEP morphology of 16 patients undergoing clipping of an unruptured MCA aneurysm was studied. We applied the Morph-Fréchet index for each recorded SEP (at 30-second intervals), quantifying the pattern shape change with regard to the average SEP recorded after dura opening (baseline). We also compared 3 measurements of the SEP morphology, without and with GARCH-derived filter. Filtered Morph-Fréchet never exceeded the individual's "normality" range in baseline but did so in 81% of the risk phase on average across the 16 subjects, which is more than that for amplitude (36%, P = .002). This pilot study indicates that a measurement derived from the networking nature of the brain was sensitive to blood flow reduction. The SEP morphology approach promises to improve SEP monitoring sensitivity during clipping of unruptured MCA aneurysms. New and Noteworthy. The higher sensitivity to blood flow reduction of SEP morphology than amplitude promises to improve the effectiveness of intraoperative monitoring during MCA aneurysm clipping procedures.

3D rotational fluoroscopy for intraoperative clip control in patients with intracranial aneurysms--assessment of feasibility and image quality

Background

Mobile 3D fluoroscopes have become increasingly available in neurosurgical operating rooms. In this series, the image quality and value of intraoperative 3D fluoroscopy with intravenous contrast agent for the evaluation of aneurysm occlusion and vessel patency after clip placement was assessed in patients who underwent surgery for intracranial aneurysms.

Materials and methods

Twelve patients were included in this retrospective analysis. Prior to surgery, a 360° rotational fluoroscopy scan was performed without contrast agent followed by another scan with 50 ml of intravenous iodine contrast agent. The image files of both scans were transferred to an Apple PowerMac® workstation, subtracted and reconstructed using OsiriX® free software. The procedure was repeated after clip placement. Both image sets were compared for assessment of aneurysm occlusion and vessel patency.

Results

Image acquisition and contrast administration caused no adverse effects. Image quality was sufficient to follow the patency of the vessels distal to the clip. Metal artifacts reduce the assessability of the immediate vicinity of the clip. Precise image subtraction and post-processing can reduce metal artifacts and make the clip-site assessable and depict larger neck-remnants.

Conclusion

This technique quickly supplies images at adequate quality to evaluate distal vessel patency after aneurysm clipping. Significant aneurysm remnants may be depicted as well. As it does not require visual control of all vessels that are supposed to be evaluated intraoperatively, this technique may be complementary to other intraoperative tools like indocyanine green videoangiography and micro-Doppler, especially for the assessment of larger aneurysms. At the momentary state of this technology, it cannot replace postoperative conventional angiography. However, 3D fluoroscopy and image post-processing are young technologies. Further technical developments are likely to result in improved image quality.

Adenosine-induced transient asystole during intracranial aneurysm surgery: indications, dosing, efficacy, and risks

BACKGROUND

Several flow-arrest techniques have been introduced for the treatment of complex aneurysms that cannot be treated with conventional clipping or endovascular coil embolization. Adenosine-induced transient asystole is an alternative method of flow arrest. However, given the limited number of studies that have reported on this topic, there is no consensus regarding the dose, regimen, efficacy, and potential risks of adenosine.

METHOD

A total of 22 aneurysms in 22 different patients that underwent adenosine-induced transient asystole during aneurismal neck clipping within the past 4 years were retrospectively reviewed. Adenosine was administrated intravenously in a test-incremental manner (starting with 6-12 mg and then giving additional doses as needed) in 11 patients and in an estimated manner (pre-calculated as 0.3-0.4 mg/kg) in 11 patients.

RESULTS

Overall, the study consisted of 18 unruptured saccular aneurysms, three ruptured saccular aneurysms, and a ruptured pseudoaneurysm. Adenosine-induced transient asystole was used in cases of temporary clipping inability, wide necked aneurysm, deep-seated aneurysm, or a thin aneurysm wall. The number of administrations, dose (mg/kg in ideal body weight) and duration of asystole were 1-4 (mean, 2.3) times, 0.08-1.27 (mean, 0.36) mg/kg and 0-30 (mean 13) seconds in the test-incremental manner and 1-2 (mean, 1.09) times, 0.24-0.42 (mean, 0.34) mg/kg and 13-41 (mean, 24) seconds in the estimated manner, respectively. There was a linear relationship between the dose and the duration of asystole. Twenty out of 22 aneurysms were clipped successfully with adenosine-induced transient asystole. However, in the other two cases, additional suction decompression was required for the final clipping. Adenosine-related cardiologic complications occurred in two cases of self-limited atrial fibrillation during restoration of the cardiac rhythm.

CONCLUSIONS

In our experience, adenosine-induced transient asystole was safe and helpful for satisfactory clipping of a complicated aneurysm. An estimated dose injection of adenosine was more convenient than the test-incremental method and did not result in serious cardiologic problems.

Ischemic Event and Risk Factors of Embolic Stroke in Atherosclerotic Cerebral Aneurysm Patients Treated with a New Clipping Technique

BACKGROUND

We would like to know the exact rate of ischemic event and the risk factors associated with embolic stroke by treatment of atherosclerotic cerebral aneurysm with a new technique.

METHODS

This is a retrospective cohort study in patients diagnosed as unruptured atherosclerotic cerebral aneurysm who underwent microsurgical clipping between January 2012 and August 2014. All intraoperative video recordings were reviewed and chosen in patients who were identified as atherosclerotic lesion on the dome, neck, or parent artery of the aneurysm. The demographic, radiographic, operative, and postoperative data were collected. The primary end point was the incidence of cerebral infarction and the neurologic outcomes using the discharge modified Rankin Scale (mRS) score at postoperation time. A statistical analysis of the factors associated with embolic stroke was done by Fisher exact and Wilcoxon rank-sum tests. The individual surgical technique was demonstrated as an illustration for use as a guide.

RESULTS

Among 103 atherosclerotic cerebral aneurysms, only 3 patients (2.9%) were associated with postoperative cerebral infarction and 1 of them had permanent neurologic deficit. A good mRS score (0-2) was found in 99% of patients and only 1% had a fair mRS score (3-4). A factor associated with ischemic outcome was duration of operation (P = .046). The differences in the atherosclerotic location showed no statistical significance.

CONCLUSIONS

We found a very low incidence of embolic infarction after clipping of an atherosclerotic cerebral aneurysm with our new technique. Only duration of the operation time was a dependent risk factor for embolic infarction.

Risk Factors for Cerebral Vasospasm Following Aneurysmal Subarachnoid Hemorrhage: A Review of the Literature

OBJECTIVE

To examine the literature on risk factors for cerebral vasospasm (CV), one of the most serious complications following aneurysmal subarachnoid hemorrhage (SAH), with special reference to the definition of CV.

METHODS

Using standard search engines, including PubMed, the medical literature on risk factors for CV after SAH was reviewed, and the best definition representative of CV was searched.

RESULTS

Severe SAH evident on computed tomography scan was the only consistent risk factor for CV after SAH. Effects of risk factors on CV, including age, clinical grade, rebleeding, intraventricular or intracerebral hemorrhage on computed tomography scan, acute hydrocephalus, aneurysm site and size, leukocytosis, interleukin-6 level, and cardiac abnormalities, appeared to be associated with the severity of SAH rather than each having a direct effect. Cigarette smoking, hypertension, and left ventricular hypertrophy on electrocardiogram were associated with CV without any relationship to SAH severity. With regard to parameters representative of CV, the grade of angiographic vasospasm (i.e., the degree of arterial narrowing evident on angiography) was the most adequate. Nevertheless, few reports on the risk factors associated with angiographic vasospasm grade have been reported to date.

CONCLUSIONS

Severe SAH evident on computed tomography scan appears to be a definite risk factor for CV after SAH, followed by cigarette smoking, hypertension, and left ventricular hypertrophy on electrocardiogram. To understand the pathogenesis of CV, further studies on the relationships between risk factors, especially factors not related to the severity of SAH, and angiographic vasospasm grade are necessary.

Clinical Risk Factors Affecting Procedure-Related Major Neurological Complications in Unruptured Intracranial Aneurysms

PURPOSE

The operative risk and natural history rupture risk for the treatment of unruptured intracranial aneurysms (UIAs) should be evaluated. The purpose of this study was to report our experience with treating UIAs and to outline clinical risk factors associated with procedure-related major neurological complications.

MATERIALS AND METHODS

We treated 1158 UIAs in 998 patients over the last 14 years. All patients underwent operation performed by a single microvascular surgeon and two interventionists at a single institution. Patient factors, aneurysm factors, and clinical outcomes were analyzed in relation to procedure-related complications.

RESULTS

The total complication rate was 22 (2.2%) out of 998 patients. Among them, complications developed in 14 (2.3%) out of 612 patients who underwent microsurgery and in 8 (2.1%) out of 386 patients who underwent endovascular procedures. One patient died due to intraoperative rupture during an endovascular procedure. The procedure-related complication was highly correlated with age (p=0.004), hypertension (p=0.002), and history of ischemic stroke (p<0.001) in univariate analysis. The multivariate analysis revealed previous history of ischemic stroke (p=0.001) to be strongly correlated with procedure-related complications.

CONCLUSION

A history of ischemic stroke was strongly correlated with procedure-related major neurological complications when treating UIAs. Accordingly, patients with UIAs who have a previous history of ischemic stroke might be at risk of procedure-related major neurological complications.

Influence of cumulative surgical experience on the outcome of poor-grade patients with ruptured intracranial aneurysm

BACKGROUND

The expansion of endovascular techniques for intracranial aneurysms has led to a global decrease in vascular neurosurgery activity. This situation might impact neurosurgeons' level of expertise, even though they all might have to deal with this surgically challenging pathology. In that context, we wanted to assess the impact of cumulative surgical experience on the outcome of patients with poor-grade subarachnoid haemorrhage (SAH) and intracerebral haemorrhage (ICH) treated by microsurgery.

METHODS

Sixty-seven patients who underwent surgery for a ruptured aneurysm with SAH and ICH, and a WFNS scale of IV/V, were included. Surgeries were performed by five surgeons, whose experience was judged by the total number of aneurysm surgeries performed. The outcome was assessed by three indicators: intraoperative rupture (IOR), early mortality, and the modified Rankin Scale at last follow-up. The time of IOR was reported on an IOR score. The correlation between surgical experience and outcome was assessed by linear regression. Nonlinear regression was used to assess the correlation of the data with a learning curve model.

RESULTS

The analysis showed an influence of surgical experience on intraoperative rupture, with no effect on long-term outcome. No influence was found on early mortality. Increased surgical experience seems to reduce IOR during aneurysm dissection and clip repositioning. Intraoperative rupture data fit Wright's learning curve model.

CONCLUSION

This study suggests a direct impact of cumulative experience on the course of ruptured aneurysm surgery and pleads for the use of training and simulation programmes dedicated to neurovascular surgery.

Controversies in the anesthetic management of intraoperative rupture of intracranial aneurysm

Despite great advancements in the management of aneurysmal subarachnoid hemorrhage (SAH), outcomes following SAH rupture have remained relatively unchanged. In addition, little data exists to guide the anesthetic management of intraoperative aneurysm rupture (IAR), though intraoperative management may have a significant effect on overall neurological outcomes. This review highlights the various controversies related to different anesthetic management related to aneurysm rupture. The first controversy relates to management of preexisting factors that affect risk of IAR. The second controversy relates to diagnostic techniques, particularly neurophysiological monitoring. The third controversy pertains to hemodynamic goals. The neuroprotective effects of various factors, including hypothermia, various anesthetic/pharmacologic agents, and burst suppression, remain poorly understood and have yet to be further elucidated. Different management strategies for IAR during aneurysmal clipping versus coiling also need further attention.

Patterns in neurosurgical adverse events: open cerebrovascular neurosurgery

OBJECT

As part of a project to devise evidence-based safety interventions for specialty surgery, we sought to review current evidence concerning the frequency of adverse events in open cerebrovascular neurosurgery and the state of knowledge regarding methods for their reduction. This review represents part of a series of papers written to consolidate information about these events and preventive measures as part of an ongoing effort to ascertain the utility of devising system-wide policies and safety tools to improve neurosurgical practice.

METHODS

The authors performed a PubMed search using search terms "cerebral aneurysm", "cerebral arteriovenous malformation", "intracerebral hemorrhage", "intracranial hemorrhage", "subarachnoid hemorrhage", and "complications" or "adverse events." Only papers that specifically discussed the relevant complication rates were included. Papers were chosen to be included to maximize the range of rates of occurrence for the reported adverse events.

RESULTS

The review revealed hemorrhage-related hyperglycemia (incidence rates ranging from 27% to 71%) and cerebral salt-wasting syndromes (34%-57%) to be the most common perioperative adverse events related to subarachnoid hemorrhage (SAH). Next in terms of frequency was new cerebral infarction associated with SAH, with a rate estimated at 40%. Many techniques are advocated for use during surgery to minimize risk of this development, including intraoperative neurophysiological monitoring, but are not universally used due to surgeon preference and variable availability of appropriate staffing and equipment. The comparative effectiveness of using or omitting monitoring technologies has not been evaluated. The incidence of perioperative seizure related to vascular neurosurgery is unknown, but reported seizure rates from observational studies range from 4% to 42%. There are no standard guidelines for the use of seizure prophylaxis in these patients, and there remains a need for prospective studies to support such guidelines. Intraoperative rupture occurs at a rate of 7% to 35% and depends on aneurysm location and morphology, history of rupture, surgical technique, and surgeon experience. Preventive strategies include temporary vascular clipping. Technical adverse events directly involving application of the aneurysm clip include incomplete aneurysm obliteration and parent vessel occlusion. The rates of these events range from 5% to 18% for incomplete obliteration and 3% to 12% for major vessel occlusion. Intraoperative angiography is widely used to confirm clip placement; adjuncts include indocyanine green video angiography and microvascular Doppler ultrasonography. Use of these technologies varies by institution.

DISCUSSION

A significant proportion of these complications may be avoidable through development and testing of standardized protocols to incorporate monitoring technologies and specific technical practices, teamwork and communication, and concentrated volume and specialization. Collaborative monitoring and evaluation of such protocols are likely necessary for the advancement of open cerebrovascular neurosurgical quality.

Does the impact of elective temporary clipping on intraoperative rupture really influence neurological outcome after surgery for ruptured anterior circulation aneurysms?--A prospective multivariate study

BACKGROUND

Elective temporary clipping (ETC) is increasingly used in surgery for aneurysms. This study was to assess whether the impact of ETC on intraoperative aneurysmal rupture (IAR) translates into neurological outcome.

METHODS

Patients who underwent surgery for ruptured anterior circulation aneurysms were prospectively studied for various factors related to ETC, IAR and neurological outcome at 3 months. Univariate and multivariate analyses were performed using SPSS20.

RESULTS

Of the total 273 ruptured aneurysm surgeries studied, IAR was observed in only six out of 132 aneurysms (4.5 %) who had ETC, compared with 78 out of 141 (55.3 %) without ETC (p < 0.001). Aneurysms complicated by IAR had significantly longer clipping time (8.3 min) compared with those without IAR (1.9 min) (p < 0.001). IAR had significant association with unfavorable outcome (38 % vs. 24 %) (p = 0.02). Patients with ETC had significantly shorter clipping time (2.9 min) compared with those without ETC (4.8 min) (p = 0.02). Unfavorable outcome was noted in 30 out of 132 with ETC (23 %), compared with 48 out of 141 without ETC (34 %) (p = 0.04). This beneficial effect was nonsignificantly greater in younger and good clinical grade patients. While episodes of ETC within clipping time of 20 min did not show significant difference in outcome, repeated rescue clipping (45 % unfavorable outcome, p = 0.048) and total clipping time of at least 20 min (75 % unfavorable outcome, p = 0.008) had significant impact on outcome. In multivariate analysis, the use of ETC (p = 0.027) and total temporary clipping less than 20 min (p = 0.049) were noted to result in significantly better outcome, independent of other factors.

CONCLUSIONS

The use of ETC decreased the occurrence of IAR and the total clipping time, thereby leading to significantly better outcome, independent of other factors. While repeated elective clipping within total clipping time of 20 min did not influence outcome, repeated rescue clipping and total clipping time of at least 20 min had significant impact on outcome.

Perioperative complications of superficial temporal artery to middle cerebral artery bypass for the treatment of complex middle cerebral artery aneurysms

OBJECT

Only a few studies have reported the risk of ischemic complications occurring when superficial temporal artery (STA) to middle cerebral artery (MCA) anastomosis is performed during surgery for complex MCA aneurysms.

SUBJECTS AND METHODS

This is a retrospective study of 10 patients (age 52-73) with MCA aneurysms treated with revascularization surgery. The aneurysms were 10-50mm in size (mean: 21mm). We studied the causes and frequency of ischemic complications by analyzing postoperative magnetic resonance imaging.

RESULTS

Postoperative diffusion-imaging confirmed ischemic complications in six of the 10 patients (in two of the five ruptured aneurysms and in four of the five unruptured). The ischemic complications that observed were infarction of the lenticulostriate artery territory in three cases, cortical infarction in two cases, and cerebral infarction that was likely to be due to cerebral vasospasm in one case. In one case, both cortical infarction and infarction of the lenticulostriate artery territory were observed. The Glasgow Outcome Scale (GOS) scores at the time of discharge indicated good recovery (GR) and moderate disability (MD) in seven cases, severe disability (SD) in two cases, and death (D) in one case.

CONCLUSIONS

The present study suggests the possibility that STA-MCA anastamosis in surgeries for MCA aneurysms can be performed with comparatively better safety. However, the temporary occlusion time with this surgery is longer than that with a temporary clipping for aneurysmal surgery; thus, we believe that adequate countermeasures are required to prevent ischemic complications.

Ischemia changes and tolerance ratio of evoked potential monitoring in intracranial aneurysm surgery

OBJECTIVE

We assessed the relationship between cerebral ischemia-induced changes in evoked potentials and the degree of ischemia tolerance.

METHODS

47 patients underwent somatosensory evoked potential (SEP) and motor evoked potential (MEP) monitoring in intracranial aneurysm surgery. Three duration parameters (time) were recorded: Time 1, from the starting of temporary occlusion unavoidable in aneurysm surgery to the time the evoked potentials decrease from basal level to reaching the warning criterion; Time 2, from evoked potentials reaching the warning criterion to the time the blood flow was resumed; Time 3, after resuming the blood flow, the time it took the evoked potentials to recover to baseline. All three times can be reliably calculated in the SEP recording, but not in the MEP recording which consisted of either unchanged amplitudes or abruptly changing amplitudes, making it impossible to obtain Time 1. The ischemic tolerance ratio (ITR) was calculated as ITR=time 2/time 1×100%. New decreasing myodynamia and fresh infarction after the surgery were employed for evaluating neurological deficits postoperatively, and their correlations with the ischemia-induced changes of evoked potentials recorded during the surgery were analyzed.

RESULTS

We found a change in SEPs in 12 patients whose cerebral ischemia was induced by temporary occlusion of the aneurysm's parent artery. We also found the development of postoperative neurological deficits in 4 patients whose ischemic tolerance ratio (ITR) reached over 80%, while no deficits were found in the other 8 patients whose ITR was less than 50%. MEP changes were seen in 4 patients whose cerebral ischemia was caused by accidentally clamping the perforating branches, causing the development of postoperative neurological deficits but not necessarily leading to significant SEP changes.

CONCLUSION

The Ischemia tolerance ratio (ITR) in SEP recordings is valuable to predicting postoperative neurological deficits caused by temporary occlusion of aneurysm's parent artery. Maintaining the ITR under 50% during operation can effectively avoid postoperative neurological deficits, while an ITR above 80% reliably forecasts postoperative neurological deficits. Complementary to SEPs, MEP recordings are particularly valuable in monitoring ischemic effects caused by accidentally clamping perforating branches. Taken together, this system of monitoring makes it possible to promptly adjust surgery procedures and minimize postoperative neurological deficits.

Acute postoperative neurological deterioration associated with surgery for ruptured intracranial aneurysm: incidence, predictors, and outcomes

OBJECT

Subarachnoid hemorrhage (SAH) results in significant morbidity and mortality, even among patients who reach medical attention in good neurological condition. Many patients have neurological decline in the perioperative period, which contributes to long-term outcomes. The focus of this study is to characterize the incidence of, characteristics predictive of, and outcomes associated with acute postoperative neurological deterioration in patients undergoing surgery for ruptured intracranial aneurysm.

METHODS

The Intraoperative Hypothermia for Aneurysm Surgery Trial (IHAST) was a multicenter randomized clinical trial that enrolled 1001 patients and assesssed the efficacy of hypothermia as neuroprotection during surgery to secure a ruptured intracranial aneurysm. All patients had a radiographically confirmed SAH, were classified as World Federation of Neurosurgical Societies (WFNS) Grade I-III immediately prior to surgery, and underwent surgery to secure the ruptured aneurysm within 14 days of SAH. Neurological assessment with the National Institutes of Health Stroke Scale (NIHSS) was performed preoperatively, at 24 and 72 hours postoperatively, and at time of discharge. The primary outcome variable was a dichotomized scoring based on an IHAST version of the Glasgow Outcome Scale (GOS) in which a score of 1 represents a good outcome and a score > 1 a poor outcome, as assessed at 90-days' follow-up. Data from IHAST were analyzed for occurrence of a postoperative neurological deterioration. Preoperative and intraoperative variables were assessed for associations with occurrence of postoperative neurological deterioration. Differences in baseline, intraoperative, and postoperative variables and in outcomes between patients with and without postoperative neurological deterioration were compared with Fisher exact tests. The Wilcoxon rank-sum test was used to compare variables reported as means. Multiple logistic regression was used to adjust for covariates associated with occurrence of postoperative deficit.

RESULTS

Acute postoperative neurological deterioration was observed in 42.6% of the patients. New focal motor deficit accounted for 65% of postoperative neurological deterioration, while 60% was accounted for using the NIHSS total score change and 51% by Glasgow Coma Scale score change. Factors significantly associated with occurrence of postoperative neurological deterioration included: age, Fisher grade on admission, occurrence of a procedure prior to aneurysm surgery (ventriculostomy), timing of surgery, systolic blood pressure during surgery, ST segment depression during surgery, history of abnormality in cardiac valve function, use of intentional hypotension during surgery, duration of anterior cerebral artery occlusion, intraoperative blood loss, and difficulty of aneurysm exposure. Of the 426 patients with postoperative neurological deterioration at 24 hours after surgery, only 46.2% had a good outcome (GOS score of 1) at 3 months, while 77.7% of those without postoperative neurological deterioration at 24 hours had a good outcome (p < 0.05).

CONCLUSIONS

Neurological injury incurred perioperatively or in the acute postoperative period accounts for a large percentage of poor outcomes in patients with good admission WFNS grades undergoing surgery for aneurysmal SAH. Avoiding surgical factors associated with postoperative neurological deterioration and directing investigative efforts at developing improved neuroprotection for use in aneurysm surgery may significantly improve long-term neurological outcomes in patients with SAH.

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.

Role of calcification in the outcomes of treated, unruptured, intracerebral aneurysms

PURPOSE

This study examined clinical and aneurysm characteristics in patients with unruptured aneurysms, treated with either coiling or clipping at a single institution, with the primary outcome-Glasgow Outcome Score (GOS)-measured at 6 months after treatment.

METHODS

Data was obtained by a retrospective review of a prospective registry of consecutive cases of unruptured intracranial aneurysms treated at a single institution from 2002 to mid 2007. Demographic data, number, location, and size of aneurysms, calcification, mode of treatment, ASA score, presence of a stroke on post-op imaging, and GOS were recorded. Medical 9.4 for PC was utilized for statistical analysis.

RESULTS

There were 225 procedures performed in 208 patients to treat 252 aneurysms. The mean age was 54.6 years, 74.5% were female, the mean ASA score was 2.45, and 72.2% were smokers. Mean aneurysm size was 8.6 mm. A total of 157 (70%) craniotomies and 68 (30%) coiling procedures were performed. Coiling was utilized more frequently in the posterior circulation [18/32 (56%) posterior circulation, 50/193 (29.9%) anterior circulation, p < 0.001 Chi-square]. Length of hospital stay averaged 5.3 days [6.2 vs. 3.2 clip/coil, p < 0.001, Mann-Whitney]. Overall favorable outcome of GOS 4-5 measured at 6 months post-procedure was 93.3% [145/157 (92.3%) clip, 66/68 (97%) coil, p = 0.3 Chi-square], with a single mortality in the coil group. There was radiographic evidence of a post-procedure stroke on CT in 31 (13.8%) [28/157 (17.8%) clip, 3/68 (4.4%) coil, p < 0.001, Chi-square], but only 11(35%) were symptomatic. All long-term morbidity was attributable to stroke except for one case of late hydrocephalus. Utilizing a logistic regression multivariate analysis (forward), none of the examined factors (age, ASA score, sex, surgeon, posterior circulation, number of aneurysms treated at one sitting, size of aneurysm, smoking status, or type of therapy) related to outcome except calcified aneurysm [20/25 (80%) calcified, 191/200 (95.5%) non-calcified, p < 0.01 Chi-square] with an OR = 7.8 (2.2-28.4, 95% C.I.). Although a univariate analysis of aneurysm size versus outcome achieves statistical significance [p = 0.05, logistic regression (forced)], when the calcified cases are removed from consideration, it does not [p = 0.55, OR = .95, (.82-1.1), 95% C.I.]. Excluding patients with calcified aneurysms resulted in the following calculation of favorable outcome: 94.2% (130/138) clip and 98.4% (61/62) coil [p = 0.33, Chi-square].

CONCLUSIONS

In this study, the presence of calcification in an aneurysm was the sole marker of adverse outcome. Larger aneurysms tended to be more likely to be calcified. Size by itself did not have an adverse affect on outcome. Clipping or clip reconstruction of calcified aneurysms is a significant source of morbidity in the treatment of unruptured aneurysms (Odds ratio 7.8).

Cerebral watershed hypoperfusion in subarachnoid hemorrhage: computed tomography perfusion analysis

OBJECT

A better understanding of the pathophysiology of vasospasm-induced delayed cerebral ischemia and earlier detection of hypoperfusion before ischemic injury are needed to guide therapy in subarachnoid hemorrhage (SAH). The cerebrovascular physiology of the major arterial territories differs from that of the watershed zones (WZs) in a way that would suggest a differential topographic sensitivity of the brain to vasospasm. The primary end point of the study was to investigate the vasospasm-induced hypoperfusion in relation to cerebrovascular topography and timing from the onset of SAH.

METHODS

Forty-one patients were prospectively enrolled and scheduled for perfusion-weighted (PW) CT at 3 time points (≤ 3 days, Days 4-8, and Days 9-15 after SAH). Perfusion-weighted CT maps were visually assessed for side-to-side perfusion asymmetry. The PW CT topographic pattern was categorized into absence of asymmetry, WZ, and vascular territory hypoperfusion. Perfusion-weighted CT revision was performed by investigators blinded to clinical information. The null hypothesis for the primary end point was that there would be no difference in hypoperfusion space-time distribution among the different vascular territories. Multivariate logistic regression and Cox proportional hazards modeling were used for statistical analysis.

RESULTS

Delayed cerebral ischemia occurred in 26 patients and its predicting variables were increasing age (p = 0.045), Fisher grade (p = 0.007), and hypoperfusion on the PW CT performed within the 1st 72 hours after SAH (p = 0.004). The timing of the PW CT with respect to the day of SAH affected the topographic pattern of hypoperfusion: watershed-zone hypoperfusion was more common within the first 3 days after SAH (p = 0.018), while the proportion of territorial hypoperfusion increased subsequently. Among the different covariates, a young age was independently associated with a higher risk of developing hypoperfusion in the WZs (p = 0.02).

CONCLUSIONS

This study suggests the existence of a cerebral topographic heterogeneity to the hemodynamic effects of SAH and differential pathogenetic mechanisms of hypoperfusion according to timing, age, and brain topography. Hypoperfusion in the WZs may be an early precursor to more profound ischemic events. The PW CT detection of such brain-sensitive zones could offer a warning signal of the early hemodynamic effects of SAH and cerebral vasospasm.

Surgical management of aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a common and often devastating condition that requires prompt neurosurgical evaluation and intervention. Modern management of aSAH involves a multidisciplinary team of subspecialists, including vascular neurosurgeons, neurocritical care specialists and, frequently, neurointerventional radiologists. This team is responsible for stabilizing the patient on presentation, diagnosing the offending ruptured aneurysm, securing the aneurysm, and managing the patient through a typically prolonged and complicated hospital course. Surgical intervention has remained a definitive treatment for ruptured cerebral aneurysms since the early 1900s. Over the subsequent decades, many innovations in microsurgical technique, adjuvant maneuvers, and intraoperative and perioperative medical therapies have advanced the care of patients with aSAH. This report focuses on the modern surgical management of patients with aSAH. Following a brief historical perspective on the origin of aneurysm surgery, the topics discussed include the timing of surgical intervention after aSAH, commonly used surgical approaches and craniotomies, fenestration of the lamina terminalis, intraoperative neurophysiological monitoring, intraoperative digital subtraction and fluorescent angiography, temporary clipping, deep hypothermic cardiopulmonary bypass, management of acute hydrocephalus, cerebral revascularization, and novel clip configurations and microsurgical techniques. Many of the topics highlighted in this report represent some of the more debated techniques in vascular neurosurgery. The popularity of such techniques is constantly evolving as new studies are performed and data about their utility become available.

Effects of temporary clipping during aneurysm surgery

OBJECTIVE

Intraoperative aneurysm rupture is associated with a high morbidity and mortality. Temporary vessel occlusion is an integral part of aneurysm clipping to avoid intraoperative hemorrhage. The information concerning the role of temporary occlusion regarding the development of cerebral vasospasm is sparse. The aim of this study was to provide more information in this field.

METHODS

We operated on 292 patients suffering from cerebral aneurysms. The data were reviewed from a prospectively collected databank, which includes information about the severity of subarachnoid hemorrhage, as well as transcranial Doppler data and surgical data such as temporary occlusion.

RESULTS

In 50% of our patients, temporary occlusion was performed during surgery. Twenty-nine percent showed an ischemic lesion in the CCT post-operatively, and in 58% of these patients, temporary occlusion was performed (versus 47% without temporary occlusion, p = 0.09). The mean occlusion time was longer in patients with radiologic signs of infarction. Furthermore, patients having unfavorable outcome showed a longer temporary occlusion time. Thirty-four percent of patients who underwent temporary vessel occlusion developed vasospasm postoperatively (versus 20% without temporary occlusion, p < 0.006). Temporary occlusion time correlated to the development of vasospasm as defined by transcranial Doppler flow velocity. Forty-eight percent of the patients treated using temporary occlusion suffered from middle cerebral artery aneurysm (versus 22% without temporary occlusion, p < 0.0001). An increased blood flow velocity was mostly seen in this region (p < 0.003).

CONCLUSION

According to our results, it seems to be the possible that temporary vessel occlusion is an additional factor in aggravating vasospasm after aneurysmatic subarachnoid hemorrhage.

IHAST II and the response of neuroanaesthetists

Deliberate mild hypothermia was first used in 1955 as an intraoperative technique to ameliorate new neurological deficits following cerebral aneursym clipping, and subsequently was also used following neonatal asphyxia, head trauma and cardiac arrest. The Intraoperative Hypothermia for Aneurysm Surgery Trial (IHAST II) randomized control trial was designed to determine the effectiveness of mild hypothermia to decrease neurological deficits following aneurysm surgery. No overall benefit was demonstrated in the hypothermic group versus normothermic group (67% versus 63% good outcome; p=0.32), with a higher rate of bacteraemia in the hypothermic group (5% versus 3%; p=0.05). We undertook a survey of Australasian and Asian neuroanaesthetists to determine whether their thermal management of patients undergoing cerebral aneursym clipping had changed in response to the IHAST II trial results.

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.

Risk factors for ischemic lesions following aneurysmal subarachnoid hemorrhage

Object. The aim of this study was to test whether enoxaparin treatment (40 mg subcutaneously once daily) reduces the risk of cerebral infarction after subarachnoid hemorrhage (SAH) and to investigate predictive risk factors for permanent ischemic lesions visible on follow-up computerized tomography (CT) scans obtained 3 months after SAH.

Methods. After undergoing surgery for a ruptured aneurysm, 170 patients were randomized in a prospective, double-blind, placebo-controlled trial to test the effect of enoxaparin on the occurrence of ischemic lesions, which were demonstrated on follow-up CT scans available for 156 patients. The presence of lesions correlated highly with an impaired outcome, as assessed using both the Glasgow Outcome and modified Rankin Scales (p < 0.01). Lesions occurred in 101 (65%) of the 156 patients. In half of the patients (51 patients) no lesion was visible on the CT scan obtained on the 1st postoperative day in 51 patients. On univariate analysis, the presence of lesions at 3 months post-SAH was not associated with enoxaparin treatment but did correlate with several clinical, radiological, and prehemorrhage variables. Significant independent risk factors for lesions consisted of an impaired initial clinical condition (odds ratio [OR] 2.63, 95% confidence interval [CI] 1.03–6.73), amount of subarachnoid blood (OR 6.51, 95% CI 2.27–18.65), nocturnal occurrence of SAH (that is, between 12:01 a.m. and 8:00 a.m.; OR 4.32, 95% CI 1.28–14.52), fixed symptoms of delayed ischemia (OR 5.21, 95% CI 1.02–26.49), duration of temporary artery occlusion during surgery (OR 1.66 per minute, 95% CI 1.20–2.31), and body mass index (OR 1.13/kg/m2, 95% CI 1.01–1.28).

Conclusions The presence of ischemic lesions can be predicted by the severity of bleeding, delayed cerebral ischemia, excess weight, duration of temporary artery occlusion, and occurrence of nocturnal aneurysm rupture.

PAR-1 deficiency protects against neuronal damage and neurologic deficits after unilateral cerebral hypoxia/ischemia

Cardiovascular and neurologic surgeries often involve a temporary reduction in cerebral blood flow. In these conditions, as well as during cerebral ischemia and traumatic brain injury, the temporary loss of oxygen and glucose initiates a cascade of cellular events that culminate in neuronal death and damage. Understanding the mechanisms that contribute to neuronal death after hypoxia/ischemia is critically important for treatment of such brain injury. Here, we use a model of combined cerebral hypoxia/ischemia (H/I) to examine the role of protease-activated receptor-1 (PAR-1) in hypoxic/ischemic neuronal damage. Our data show that PAR-1-deficient mice have smaller lesion volumes than wild-type controls after 45 minutes of H/I. The results of the genetic block of PAR-1 were corroborated using a PAR-1 antagonist, which decreased infarct volume in wild-type C57Bl6 mice. Examination of cellular responses to H/I reveals that PAR-1 -/- animals have less cellular death and diminished glial fibrillary acidic protein expression. Additionally, PAR-1 -/- mice exhibit less motor behavior impairment in rotorod and inverted wire-hang tests. These data suggest that PAR-1 contributes to hypoxic/ischemic brain injury and are consistent with other studies that implicate serine proteases and their receptors in neuropathology after cerebral insults.

Extracorporeal femoral to carotid artery perfusion in selective brain cooling for a giant aneurysm

Giant partially thrombosed intracranial aneurysms are a challenge to treat surgically, and they are also unsuitable for coil embolization. The current options for treatment include extracranial-intracranial bypass followed by parent artery occlusion or direct surgical occlusion in which deep hypothermic circulatory arrest is used. The authors report the use of another approach in the treatment of a giant anterior circulation aneurysm: selective brain cooling accomplished by extracorporeal perfusion. This facilitated direct surgery on a 4.2-cm, partially thrombosed aneurysm of the middle cerebral artery (MCA). A brain temperature of 22 degrees C was achieved after 20 minutes of perfusion with blood cooled using an extracorporeal technique of femoral-common carotid artery perfusion. This was followed by a 20-minute period of surgical trapping of the MCA, then evacuation and clip occlusion of the aneurysm. During the period of selective brain cooling the patient's core body temperature was maintained above 35 degrees C. This technique of selective brain cooling may be a useful alternative to currently available surgical and endovascular methods of treatment for giant aneurysms.

Intraoperative factors associated with surgical outcome in patients with unruptured cerebral aneurysms: the experience of a single surgeon

OBJECT

Some well-known predictors of clinical outcomes in patients with ruptured aneurysms are not useful for forecasting outcome in patients with unruptured aneurysms. The goal of this study was to analyze outcomes in patients harboring unruptured cerebral aneurysms in different locations and to create a predictive tool for assessing both favorable outcome and morbidity in a large series of unruptured aneurysms.

METHODS

The authors analyzed data from 387 patients with nonruptured intracranial cerebral aneurysms who underwent surgery for clip placement. Intraoperative data were reviewed and seven factors that might influence outcomes were identified. These included the following: 1) aneurysm size larger than 10 mm; 2) presence of a broad aneurysm neck; 3) presence of plaque calcification near the aneurysm neck; 4) application of clips to more than one aneurysm during the same surgery; 5) temporary occlusion; 6) multiple clip applications and repositioning; and 7) use of multiple clips. The entire group of patients with unruptured aneurysms was divided into two subgroups on the basis of outcome. Each patient was subsequently assessed to formulate the factor accumulation index (FAI), the sum of different factors observed in a given patient. The subgroup of patients with expected outcomes was composed of 312 patients, whereas the subgroup of unexpected outcomes consisted of 31 patients. Depending on the anatomical locations of the aneurysms, the combined mortality-morbidity rate ranged from 5.7 to 25%, with the best results for patients harboring ophthalmic artery aneurysms and the worst results for those with vertebrobasilar system (VBS) aneurysms. The majority of patients with expected outcomes who harbored aneurysms of the middle cerebral artery, the internal carotid artery, and the VBS had a lower FAI, whereas the majority of patients with unexpected outcomes had a higher FAI.

CONCLUSIONS

It is possible to predict outcomes in patients with unruptured cerebral artery aneurysms by calculating the FAI. The rate of postoperative morbidity increases with the FAI within the range of three to four factors.

High-dose ibuprofen for reduction of striatal infarcts during middle cerebral artery occlusion in rats

OBJECT

Ibuprofen is an antiinflammatory drug that disrupts leukocyte-endothelial cell interactions by limiting expression of endothelial adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1), also known as CD54. The authors hypothesized that ibuprofen could reduce the size of the infarct associated with transient focal ischemia by inhibition of ICAM-1 expression, and they evaluated its effects in rats treated with middle cerebral artery (MCA) occlusion. Ibuprofen treatment was compared with mild systemic hypothermia, which is known to be neuroprotective and is commonly used during neurosurgical procedures.

METHODS

The maximum ibuprofen dose (240 mg/kg/day) that could be tolerated with no systemic toxicity was established in the initial experiments. In the efficacy experiment, rats were pretreated with vehicle, ibuprofen, or hypothermia (33 degrees C) prior to 2 hours of MCA occlusion; then their brains were harvested at 24 hours of reperfusion for histological studies. End-ischemic cerebral blood flow (CBF) was evaluated using [14C]iodoantipyrine autoradiography in additional cohorts. Expression of ICAM-1 within ischemic compared with nonischemic caudate nucleus and putamen (striatum) or cortex was evaluated using immunohistochemical studies. Compared with vehicle treatment, ibuprofen produced a 46.2% reduction (p = 0.01) in striatal infarcts, which was comparable to hypothermia (48.7% reduction, p = 0.02). Ibuprofen did not alter end-ischemic CBF in any region studied, and the ibuprofen treatment group had the lowest proportion of animals with marked ICAM-1 staining.

CONCLUSIONS

Ibuprofen given in maximum tolerated doses reduces the striatal infarct size after focal cerebral ischemia. The neuroprotective mechanism does not work through preservation of intraischemic CBF and is consistent with inhibition of ICAM-1 expression; however, at the doses used in this study, other effects of ibuprofen on platelet and endothelial function are possible.

Monitoring of brain tissue oxygenation during aneurysm surgery: prediction of procedure-related ischemic events

OBJECT

The aim of this study was to evaluate the feasibility of monitoring brain tissue oxygenation (PO2) during aneurysm surgery for the detection of procedure-related ischemia.

METHODS

Between 1997 and 1998, PO2 was monitored prospectively in a cohort of 40 patients (42 recordings) during aneurysm surgery in the anterior circulation within the vascular territory of the aneurysm-bearing artery. The position of the probe used to measure oxygenation levels was verified on computerized tomography (CT) scanning on the 1st postoperative day. Because of the mislocation of one probe and the malfunction of another, data from only 38 patients (40 recordings) were suitable for analysis. Relative changes from baseline to absolute nadir values of intraoperative PO2 were correlated with simultaneously recorded somatosensory evoked potentials (SSEPs), and cardiovascular and ventilatory parameters. The frequency of ischemic events was evaluated with the aid of CT on the 1st postoperative day as a substitute parameter for intraoperative ischemia. Clinical outcome was evaluated 30 days postoperatively based on the Glasgow Outcome Scale. Except for three, all patients underwent surgery for treatment of a symptomatic aneurysm. Mean baseline PO2 was 23.9 mm Hg (range 2-67.2 mm Hg) before clip application. A relative decrease in PO2 (20% decrease in value compared with baseline) occurred in 12 patients and was a sensitive indicator for the risk of ischemia during temporary arterial occlusion, but was less predictive of nonocclusive ischemia (sensitivity 0.5; positive predictive value [PPV] 0.42; p > 0.05). Results of receiver operating characteristic analysis demonstrated a postclipping PO2 nadir of 15 mm Hg as a dichotomizing threshold for the prediction of ischemia. This threshold rendered an improved sensitivity (0.9) and PPV (0.56) for procedure-related ischemia (p = 0.0003). The results of utility analysis revealed this monitoring parameter to be clinically diagnostic. Only PO2 monitoring, and not SSEP at the tibial nerve, was predictive of ischemia within the anterior cerebral artery territory.

CONCLUSIONS

Using 15 mm Hg as a dichotomizing threshold, intraoperative PO2 monitoring enables one to identify patients at risk for procedure-related ischemia during aneurysm surgery and surpasses SSEP monitoring. This newly defined threshold based on intraoperative PO2 monitoring provides a basis for studies on treatments for procedure-related ischemia during aneurysm surgery.

Temporary arterial occlusion in the repair of ruptured intracranial aneurysms: an analysis of risk factors for stroke

OBJECT

This study was performed to further elucidate technical and patient-specific risk factors for perioperative stroke in patients undergoing temporary arterial occlusion during the surgical repair of their aneurysms.

METHODS

One hundred twelve consecutive patients in whom temporary arterial occlusion was performed during surgical repair of an aneurysm were retrospectively analyzed. Confounding factors (inadvertent permanent vessel occlusion and retraction injury) were identified in six cases (5%) and these were excluded from further analysis. The demographics for the remaining 106 patients were analyzed with respect to age, neurological status, aneurysm characteristics, intraoperative rupture, duration of temporary occlusion, and number of occlusive episodes; end points considered were outcome at 3-month follow up and symptomatic and radiological stroke.

CONCLUSIONS

Overall 17% of patients experienced symptomatic stroke and 26% had radiological evidence of stroke attributable to temporary arterial occlusion. A longer duration of clip placement, older patient age, a poor clinical grade (Hunt and Hess Grades IV-V), early surgery, and the use of single prolonged clip placement rather than repeated shorter episodes were associated with a higher risk of stroke based on univariate analysis. Intraoperative aneurysm rupture did not affect stroke risk. On multivariate analysis, only poorer clinical grade (p = 0.001) and increasing age (p = 0.04) were significantly associated with symptomatic stroke risk.

Cerebral oxygen and microdialysis monitoring during aneurysm surgery: effects of blood pressure, cerebrospinal fluid drainage, and temporary clipping on infarction

OBJECT

The aim of this study was to investigate potential episodes of cerebral ischemia during surgery for large and complicated aneurysms, by examining the effects of arterial temporary clipping and the impact of confounding variables such as blood pressure and cerebrospinal fluid (CSF) drainage.

METHODS

Brain tissue PO2, PCO2, and pH, as well as temperature and extracellular glucose, lactate, pyruvate, and glutamate were monitored in 46 patients by using multiparameter sensors and microdialysis. Baseline data showed that brain tissue PO2 decreased significantly, below a mean arterial pressure (MAP) threshold of 70 mm Hg. Further evidence of its relationship with cerebral perfusion pressure was shown by an increase in mean brain tissue PO2 after drainage of CSF from the basal cisterns (Wilcoxon test, p < 0.01). Temporary clipping was required in 31 patients, with a mean total duration of 14 minutes (range 3-52 minutes), causing brain tissue PO2 to decrease and brain tissue PCO2 to increase (Wilcoxon test, p < 0.01). In patients in whom no subsequent infarction developed in the monitored region, brain tissue PO2 fell to 11 mm Hg (95% confidence interval 8-14 mm Hg). A brain tissue PO2 level below 8 mm Hg for 30 minutes was associated with infarction in any region (p < 0.05 according to the Fisher exact test); other parameters were not predictive of infarction. Intermittent occlusions of less than 30 minutes in total had little effect on extracellular chemistry. Large glutamate increases were only seen in two patients, in both of whom brain tissue PO2 during occlusion was continuously lower than 8 mm Hg for longer than 38 minutes.

CONCLUSIONS

The brain tissue PO2 decreases with hypotension, and, when it is below 8 mm Hg for longer than 30 minutes during temporary clipping, it is associated with increasing extracellular glutamate levels and cerebral infarction.

Intraoperative complications in aneurysm surgery: a prospective national study

OBJECT

With increasing use of endovascular procedures, the number of aneurysms treated surgically will decline. In this study the authors review complications related to the surgical treatment of aneurysms and address the issue of maintaining quality standards on a national level.

METHODS

A prospective, nonselected amalgamation of every aneurysm case treated in five of six neurosurgical centers in Sweden during 1 calendar year was undertaken (422 patients; 7.4 persons/100,000 population/year). The treatment protocols at these institutions were very similar. Outcome was assessed using clinical end points. In this series, 84.1% of the patients underwent surgery, and intraoperative complications occurred in 30% of these procedures. Poor outcome from technical complications was seen in 7.9% of the surgically treated patients. Intraoperative aneurysm rupture accounted for 60% and branch sacrifice for 12% of all technical difficulties. Although these complications were significantly related to aneurysm base geometry and the competence of the surgeon, problems still occurred apparently at random and also in the best of hands (17%). The temporary mean occlusion time in the patients who suffered intraoperative aneurysm rupture was twice as long as the temporary arrest of blood flow performed to aid dissection.

CONCLUSIONS

The results obtained in this series closely reflect the overall management results of this disease and support the conclusion that surgical complications causing a poor outcome can be estimated on a large population-based scale. Intraoperative aneurysm rupture was the most common and most devastating technical complication that occurred. Support was found for a more liberal use of temporary clips early during dissection, regardless of the experience of the surgeon. Temporary regional interruption of arterial blood flow should be a routine method for aneurysm surgery on an everyday basis. A random occurrence of difficult intraoperative problems was clearly shown, and this factor of unpredictability, which is present in any preoperative assessment of risk, strengthens the case for recommending neuroprotection as a routine adjunct to virtually every aneurysm operation, regardless of the surgeon's experience.

Contemporary management of subarachnoid hemorrhage and vasospasm: the UIC experience

BACKGROUND

Cerebral vasospasm is a well-known and serious complication of aneurysmal subarachnoid hemorrhage. The means of monitoring and treatment of vasospasm have been widely studied. Each neurosurgical center develops a protocol based on their experience, availability of equipment and personnel, and cost, so as to keep morbidity and mortality rates as low as possible for their patients with vasospasm.

METHODS

At the University of Illinois at Chicago, we have developed algorithms for the diagnosis and management of cerebral vasospasm based on the experience of the senior authors over the past 25 years. This paper describes in detail our approach to diagnosis and treatment of aneurysmal subarachnoid hemorrhage and vasospasm. Our discussion is highlighted with data from a retrospective analysis of 324 aneurysm patients.

RESULTS

Over 3 years, 324 aneurysms were treated; 185 (57%) were clipped, 139 (43%) were coiled. The rate of vasospasm for the 324 patients was 27%. The rate of hydrocephalus was 32% for those patients who underwent clipping, and 29% for those coiled. The immediate outcomes for those who underwent clipping was excellent in 35%, good in 38%, poor in 15.5%, vegetative in 3%, and death in 8% of the patients. For those who underwent coiling the immediate outcome was excellent in 64%, good in 14.5%, vegetative in 2.5%, and death in 14.5% of the patients. These statistics include all Hunt and Hess grades. For those patients who underwent clipping, 51% were intact at 6 months follow-up, 15% had a permanent deficit, 10% had a focal cranial nerve deficit, and 2% had died from complications not directly related to the procedure. For those patients who had undergone coiling, 75% were intact at 6 months follow-up, 12.5% had a permanent deficit, and 12.5% had a cranial nerve deficit, with no deaths.

CONCLUSIONS

The morbidity and mortality of cerebral vasospasm is significant. A good outcome after aneurysmal subarachnoid hemorrhage is dependent upon careful patient management in the preoperative, perioperative, and postoperative periods. The timely work-up and aggressive treatment of neurological deterioration, whether or not it is because of vasospasm, is paramount.

Continuous monitoring of regional cerebral blood flow during temporary arterial occlusion in aneurysm surgery

OBJECT

Temporary arterial occlusion (TAO) during aneurysm surgery carries the risk of ischemic sequelae. Because monitoring of regional cerebral blood flow (rCBF) may limit neurological damage, the authors evaluated a novel thermal diffusion (TD) microprobe for use in the continuous and quantitative assessment of rCBF during TAO.

METHODS

Following subcortical implantation of the device at a depth of 20 mm in the middle cerebral artery or anterior cerebral artery territory, rCBF was continuously monitored by TD microprobe (TD-rCBF) throughout surgery in 20 patients harboring anterior circulation aneurysms; 46 occlusive episodes were recorded. Postoperative radiographic evidence of new infarction was used as the threshold for failure of occlusion tolerance. The mean subcortical TD-rCBF decreased from 27.8+/-8.4 ml/100 g/min at baseline to 13.7+/-11.1 ml/100 g/min (p < 0.0001) during TAO. The TD microprobe showed an immediate exponential decline of TD-rCBF on clip placement. On average, 50% of the total decrease was reached after 12 seconds, thus rapidly indicating the severity of hypoperfusion. Following clip removal, TD-rCBF returned to baseline levels after an average interval of 32 seconds, and subsequently demonstrated a transient hyperperfusion to 41.4+/-18.3 ml/l 00 g/min (p < 0.001). The occurrence of postoperative infarction (15%) and the extent of postischemic hyperperfusion correlated with the depth of occlusion-induced ischemia.

CONCLUSIONS

The new TD microprobe provides a sensitive, continuous, and real-time assessment of intraoperative rCBF during TAO. Occlusion-induced ischemia is reliably detected within the 1st minute after clip application. In the future, this may enable the surgeon to alter the surgical strategy early after TAO to prevent ischemic brain injury.

Possible control of intermittent cerebral ischemia by monitoring of direct-current potentials

OBJECT

Neurosurgically induced temporary occlusion of intracranial arteries carries the risk of cerebral ischemic damage. Because negative shifts in the cortical direct-current (DC) potential indicate tissue depolarization and, thus, critical ischemic stress, the authors hypothesized that recordings of these potentials could help to determine the optimal duration and frequency of induced intermittent focal ischemia to prevent brain injury. The investigators related the results of DC recordings both to simultaneously recorded decreases in extracellular Ca++ concentration ([Ca++]o), which reflect Ca++ entry into cells, and to histological outcome.

METHODS

In cats anesthetized with halothane the effects of intermittent brief (10 minutes long, six times [6 x 10-min group]) and prolonged (20 minutes long, three times [3 x 20-min group]) episodes of middle cerebral artery occlusions were compared with those of a single continuous episode (1 x 60-min group). Laser Doppler flow probes and ion-selective microelectrodes were used to measure cerebral blood flow, DC potentials, and [Ca++]o in cortical tissues of ectosylvian gyri. Negative shifts in DC potential were evaluated in the three groups during the entire 60-minute-long period of ischemia and were smallest in the 6 x 10-min group, larger in the 3 x 20-min group, and largest in the 1 x 60-min group. Accordingly, infarct volumes were smallest in the 6 x 10-min group, intermediate in the 3 x 20-min group, and largest in the 1 x 60-min group. Decreases in ischemic [Ca++]o were significantly greater in the 1 x 60-min group than in the two groups in which there were repetitive occlusions, and recovery of [Ca++]o after reperfusion normalized only in the 1 x 60-min group.

CONCLUSIONS

The DC potential may provide a reliable measure to optimize intermittent ischemia and to achieve minimal ischemic brain injury during temporary neurosurgical occlusion of cerebral arteries.

Intraoperative variables and early outcome after aneurysm surgery

BACKGROUND

The purpose of this study was to investigate the effects of blood pressure, temperature, and anesthetic agents on outcome in patients undergoing craniotomy for cerebral aneurysms.

METHODS

All ruptured and unruptured intracranial aneurysms operated on from 1992 to 1998 were reviewed retrospectively. The data included 297 aneurysms (190 ruptured and 107 unruptured). Data were collected on variables known to influence outcome after aneurysmal subarachnoid hemorrhage as well as on intraoperative factors that might influence outcome (intraoperative blood pressure, temperature, temporary clipping, anesthetic agents). Outcome was assessed at discharge using the Glasgow Outcome Scale.

RESULTS

In univariate analysis of patients with ruptured aneurysms, younger age, better clinical grade, lower Fisher grade, lower intraoperative blood pressure (maximum systolic and mean blood pressure), smaller decrease in intraoperative compared to preoperative systolic blood pressure, shorter duration of surgery, and use of propofol, pancuronium, or N(2)O were associated with significantly better outcome. In patients with unruptured aneurysms, increased intraoperative minimum diastolic and mean blood pressure, a decrease in the difference between multiple measures of preoperative and intraoperative blood pressure, and a shorter duration of surgery were associated with significantly better outcome. Intraoperative temperature did not affect outcome in either group. In multivariate analysis of patients with ruptured aneurysms, younger age, better clinical grade, lower maximum systolic intraoperative blood pressure, shorter duration of surgery, and use of propofol were independently associated with better outcome.

CONCLUSIONS

Multivariate analysis of intraoperative factors affecting outcome in patients undergoing craniotomy for ruptured aneurysms shows that decreased intraoperative blood pressure and use of propofol are associated with improved outcome. Univariate analysis suggests that decreasing the magnitude of drop in blood pressure intraoperatively from preoperative values in patients with ruptured or unruptured aneurysms is associated with better outcome. Intraoperative hypothermia did not affect outcome.

Adverse effects of limited hypotensive anesthesia on the outcome of patients with subarachnoid hemorrhage

OBJECT

This study was aimed at clarifying the effect of intraoperative hypotensive anesthesia on the outcome of early surgery in patients with subarachnoid hemorrhage (SAH) caused by saccular cerebral aneurysms. Other factors were also screened for possible effects on the outcome.

METHODS

Hospital charts in 84 consecutive patients with SAH who underwent aneurysm clipping by Day 4 were examined. Possible factors affecting the outcome were analyzed using multiple logistic regression with the dichotomous Glasgow Outcome Scale score as the outcome variable. The relationship between the intraoperative hypotension and the occurrence and severity of vasospasm was studied using both single- and multivariate analyses.

CONCLUSIONS

Intraoperative hypotension had a significantly adverse effect on the outcome of SAH. Hypotension was also related to more frequent and severe manifestations of vasospasm. A long-lasting effect of brain retraction is possibly the cause of this phenomenon. The data contained in this study preclude the use of intraoperative hypotension even in a limited form.