Intraoperative angiography in cerebral aneurysm surgery: a prospective study of 100 craniotomies

Laser speckle contrast imaging versus microvascular Doppler sonography in aneurysm surgery: A prospective study

Objective

This study aimed to compare microvascular Doppler sonography (MDS) and laser speckle contrast imaging (LSCI) for assessing vessel patency and aneurysm occlusion during microsurgical clipping of intracranial aneurysms.

Methods

MDS and LSCI were used after clip placement during six neurovascular procedures including six patients, and agreement between the two techniques was assessed. LSCI was performed in parallel or right after MDS evaluation. The Doppler response was assessed through listening while flow in the LSCI videos was evaluated by three blinded neurovascular surgeons after the surgery. Statistical analysis determined the agreement between the techniques in assessing flow in 18 regions of interest (ROIs).

Results

Agreement between MDS and LSCI in assessing vessel patency was observed in 87 % of the ROIs. LSCI accurately identified flow in 93.3 % of assessable ROIs, with no false positive or negative measurements. Three ROIs were not assessable with LSCI due to motion artifacts or poor image quality. No complications were observed.

Conclusions

LSCI demonstrated high agreement with MDS in assessing vessel patency during microsurgical clipping of intracranial aneurysms. It provided continuous, real-time, full-field imaging with high spatial resolution and temporal resolution. While MDS allowed evaluation of deep vascular regions, LSCI complemented it by offering unlimited assessment of surrounding vessels.

Intraoperative angiography during neurosurgical procedures on patients in prone, three-quarters prone, and park-bench positions: tertiary single-center experience with systematic review and meta-analysis

BACKGROUND

There is limited evidence about the role and effectiveness of intraoperative angiography (IOA) during neurosurgical procedures with patients in prone, three-quarters prone, and park-bench positions.

OBJECTIVE

To carry out a systematic review and meta-analysis of the literature to evaluate the safety and efficacy of IOA during neurosurgical procedures.

METHODS

We reviewed (between January 1960 and July 2022) all studies in which IOAs were performed during neurosurgical procedures with patients in either prone, three-quarters prone, or park-bench positions. Additionally, a cohort of patients from our institutional experience was included. Efficacy outcomes were the rate of successful angiography and the rate of surgical adjustment/revision after IOA. Safety outcomes were the rate of angiography-related complications and mortality. Data were analyzed using a random-effects meta-analysis of proportions, and statistical heterogeneity was assessed.

RESULTS

A total of 26 studies with 142 patients plus 32 subjects from our institution were included in the analysis. The rate of successful intraoperative angiography was 98% (95% CI 94% to 99%; I²=0%). The rate of surgical adjustment/revision was 18% (95% CI 12% to 28%; I²=0%). The rate of complications related to the angiography was 1% (95% CI 0% to 5%; I²=0%). There were no deaths associated with IOA.

CONCLUSION

We found that IOA performed with patients in prone, three-quarters prone, and park-bench positions is feasible and safe with a non-negligible rate of intraoperative post-angiographical surgical adjustment/revision. Our findings suggest that the performance of IOA to complement vascular neurosurgical procedures might have a valuable role in favoring patient outcomes.

Enhance Safety in Aneurysm Surgery: Strategies for Prevention of Intraoperative Vascular Complications

Complications during surgery for intracranial aneurysms can be devastating. Notorious pitfalls include premature rupture, parent vessel occlusion, local cerebral injury and brain contusion, and incomplete neck obliteration. These unfavorable intraoperative events can result in major neurological deficits with permanent morbidity and even mortality. Herein, the author highlights the relevant surgical strategies used in his daily practice of aneurysm surgery (e.g., aneurysm clipping with adenosine-induced temporary cardiac arrest), application of which may help prevent vascular complications and enhance surgical safety through reduction of the associated risks, thus allowing improvement of postoperative outcomes. Overall, all described methods and techniques should be considered as small pieces in the complex puzzle of prevention of vascular complications during aneurysm surgery.

Intraoperative fluorescein video angiography in intracranial aneurysm surgery: single-center, observational cohort study

The aim of this study was to compare the incidence of postoperative, surgery-related complications in patients where fluorescein video angiography (FL-VA) was performed with those operated without intraoperative verification. This is an observational cohort study including 97 patients who were selected for microsurgical clipping due to intracranial aneurysm. First 52 patients enrolled in the study were operated prior to introduction of fluorescein fluorescence in our surgical workflow. These patients were considered as controls. The study group consisted of 45 consecutive patients operated with the use of fluorescein video angiography and by the same surgical team. Outcomes in both groups were compared using non-parametric test (Mann-Whitney U). Intraoperative fluorescein video angiography revealed aneurysm remnant or inadvertent vessel occlusion in 17.8% of patients. Following clip reposition, a repeated FL-VA was performed to confirm restoration of blood flow and/or complete aneurysm obliteration. Intraoperative findings were later confirmed using computed tomography angiography (CTA). None of the patients in our study group developed surgery-related complications; whereas in the control group, aneurysm remnant was discovered in 7.7%, brain ischemia in 9.6% and both of the latter in 5.8% of patients. Difference in treatment-related outcome was statistically significant (p < 0.05). Intraoperative fluorescein video angiography successfully identified aneurysm residual and adjacent artery occlusion leading to excellent outcome following clip reposition.

Detection of impending perfusion deficits by intraoperative computed tomography (iCT) in aneurysm surgery of the anterior circulation

Background

The aim of our study was to evaluate the additional benefit of intraoperative computed tomography (iCT), intraoperative computed tomography angiography (iCTA), and intraoperative computed tomography perfusion (iCTP) in the intraoperative detection of impending ischemia to established methods (indocyanine green videoangiography (ICGVA), microDoppler, intraoperative neuromonitoring (IONM)) for initiating timely therapeutic measures.

Methods

Patients with primary aneurysms of the anterior circulation between October 2016 and December 2019 were included. Data of iCT modalities compared to other techniques (ICGVA, microDoppler, IONM) was recorded with emphasis on resulting operative conclusions leading to inspection of clip position, repositioning, or immediate initiation of conservative treatment strategies. Additional variables analyzed included patient demographics, aneurysm-specific characteristics, and clinical outcome.

Results

Of 194 consecutive patients, 93 patients with 100 aneurysms received iCT imaging. While IONM and ICGVA were normal, an altered vessel patency in iCTA was detected in 5 (5.4%) and a mismatch in iCTP in 7 patients (7.5%). Repositioning was considered appropriate in 2 patients (2.2%), where immediate improvement in iCTP could be documented. In a further 5 cases (5.4%), intensified conservative therapy was immediately initiated treating the reduced CBP as clip repositioning was not considered causal. In terms of clinical outcome at last FU, mRS0 was achieved in 85 (91.4%) and mRS1-2 in 7 (7.5%) and remained mRS4 in one patient with SAH (1.1%).

Conclusions

Especially iCTP can reveal signs of impending ischemia in selected cases and enable the surgeon to promptly initiate therapeutic measures such as clip repositioning or intraoperative onset of maximum conservative treatment, while established tools might fail to detect those intraoperative pathologic changes.

Successful embolization for a traumatic pseudoaneurysm concomitant with a massive back hematoma by a prone transradial catheterization technique

A 25-year-old man with a massive traumatic subcutaneous hematoma in his back was transferred to our emergency department. Contrast-enhanced computed tomography revealed a pseudoaneurysm with extravasation within the hematoma. The patient was unable to take a supine position due to the massive back hematoma. We thus performed a transcatheter embolization of bilateral cervical branches with the patient in the prone position, via a radial artery. After two embolizations, successful hemostasis was achieved. The prone transradial catheterization technique is useful for embolization in patients who cannot be in the supine position.

Hemorrhagic stroke treated by transcranial neuroendoscopic approach

Hemorrhagic stroke (HS) is usually treated under microscopy, but recently, an increasing number of cases have been treated under neuroendoscopy. The objective of this study was to explore the feasibility and efficacy of a transcranial neuroendoscopic approach for HS. Based on etiology and clinical features, 203 HS patients were classified into two groups, with 100 patients in the primary HS (PHS) group and 103 patients in the secondary HS (SHS) group. All patients were treated either by full neuroendoscopy (FNE) or by neuroendoscopy combined with microsurgery (ECM). Outcomes were assessed according to the Glasgow Coma Scale (GCS) at discharge, and the rate of good plus excellent results was recorded as the GE rate to assess the treatment effect. All 203 patients underwent surgery successfully, with 165 patients who underwent FNE and 38 patients who underwent ECM. No patients died within 3 days after surgery, and the surgery-related mortality rate was 0%, but a total of 4 patients died by discharge, and the overall mortality rate was 1.97%. A total of 133 patients showed an excellent result and 16 showed a good result, for a total GE rate of 73%. Neuroendoscopy can provide excellent illumination, clear visualization, and multiangle views in HS. The transcranial neuroendoscopic approach is feasible and safe for both PHS and SHS and is very effective for hematoma evacuation. However, some aneurysms and most arteriovenous malformations and arteriovenous fistulas require ECM.

The value of intraoperative angiography in the time of indocyanine green videoangiography in the treatment of cerebrovascular lesions: Efficacy, workflow, risk-benefit and cost analysis A prospective study

INTRODUCTION

Intraoperative digital subtraction angiography (ioDSA) allows early treatment evaluation after neurovascular procedures. However, the value and efficiency of this procedure has been discussed controversially. We have evaluated the additional value of hybrid operating room equipped with an Artis Zeego robotic c-arm regarding cost, efficiency and workflow. Furthermore, we have performed a risk-benefit analysis and compared it with indocyanine green (ICG) angiography.

METHODS

For 3 consecutive years, we examined all neurovascular patients, treated in the hybrid operating theater in a risk-benefit analysis. After using microdoppler and ICG angiography for best operative result, every patient received an additional ioDSA to look for remnants or unfavorable clip placement which might lead to a change of operating strategy or results. Furthermore, a workflow-analysis reviewing operating steps, staff positioning, costs, technical errors or complications were conducted on randomly selected cases.

RESULTS

54 patients were enrolled in the risk-benefit analysis, 22 in the workflow analysis. The average duration of a cerebrovascular operation was 4 h 58 min 2 min 35 s accounted for ICG angiography, 46 min 4 s for ioDSA. Adverse events occurred during one ioDSA. In risk-benefit analysis, ioDSA was able to detect a perfusion rest in 2 out of 43 cases (4,7%) of aneurysm surgery, which could not have been visualized by ICG angiography before. In arterio-venous-malformation (AVM) surgery, one of 11 examined patients (7,7%) showed a remnant in ioDSA and resulted in additional resection. The average cost of an ioDSA in Ulm University can be estimated with 1928,00€.

CONCLUSION

According to our results ioDSA associated complications are low. Relevant findings in ioDSA can potentially avoid additional intervention, however, due to the high costs and lower availability, the main advantage might lie in the treatment of selected patients with complexes neurovascular pathologies since ICG angiography is equally safe but associated with lower costs and better availability.

Residual lesions in patients undergoing microsurgical clipping of cerebral aneurysms in a reference university hospital

OBJECTIVES

This study aimed to analyze the incidence and epidemiological, angiographic, and surgical aspects associated with incomplete clipping of brain aneurysms in a cohort of patients undergoing microsurgical treatment.

METHODS

The medical record data of patients who underwent microsurgery for cerebral aneurysm treatment and postoperative digital subtraction angiography, treated at the same teaching hospital between 2014 and 2019, were retrospectively analyzed. The studied variables involved epidemiological and clinical data, as well as neurological status and findings on neuroimaging. The time elapsed between hemorrhage and microsurgical treatment, data on the neurosurgical procedure employed for aneurysm occlusion, and factors associated with the treated aneurysm, specifically location and size, were also evaluated.

RESULTS

One hundred and seventeen patients were submitted to 139 neurosurgical procedures, in which 167 aneurysms were clipped. The overall rate of residual injury was 23%. Smoking (odds ratio [OR]: 3.38, 95% confidence interval [CI95%]: 1.372-8.300, p=0.008), lesion size >10 mm (OR: 5.136, CI95%: 2.240-11.779, p<0.001) and surgery duration >6 h (OR: 8.667, CI95%: 2.713-27.681, p<0.001) were found to significantly impact incomplete aneurysm occlusion in the univariate analyses.

CONCLUSION

Incomplete microsurgical aneurysm occlusion is associated with aneurysm size, complexity, and current smoking status. Currently, there is no consensus on postoperative assessment of clipped aneurysms, hindering the correct assessment of treatment outcomes.

Intraoperative Laser Speckle Contrast Imaging For Real-Time Visualization of Cerebral Blood Flow in Cerebrovascular Surgery: Results From Pre-Clinical Studies

Cerebrovascular surgery can benefit from an intraoperative system that conducts continuous monitoring of cerebral blood flow (CBF). Such a system must be handy, non-invasive, and directly integrated into the surgical workflow. None of the currently available techniques, considered alone, meets all these criteria. Here, we introduce the SurgeON™ system: a newly developed non-invasive modular tool which transmits high-resolution Laser Speckle Contrast Imaging (LSCI) directly onto the eyepiece of the surgical microscope. In preclinical rodent and rabbit models, we show that this system enabled the detection of acute perfusion changes as well as the recording of temporal response patterns and degrees of flow changes in various microvascular settings, such as middle cerebral artery occlusion, femoral artery clipping, and complete or incomplete cortical vessel cautery. During these procedures, a real-time visualization of vasculature and CBF was available in high spatial resolution through the eyepiece as a direct overlay on the live morphological view of the surgical field. Upon comparison with indocyanine green angiography videoangiography (ICG-VA) imaging, also operable via SurgeON, we found that direct-LSCI can produce greater information than ICG-VA and that continuous display of data is advantageous for performing immediate LSCI-guided adjustments in real time.

Intraoperative Use of Microscope-Integrated Flow 800 - A Valuable Tool in Surgical Management of Anterior Communicating Artery Aneurysm: Our Institutional Experience

Background:

Flow 800 is microscope-integrated analytical visualization tool which analyses the indocyanine green (ICG) video sequence and converts it into an intensity diagram. This allows an objective evaluation of the result rather than subjective assessment of ICG fluorescence. The anatomy of anterior communicating artery region is complex because of multiple vessels and perforators in small space; hence, there is a need of objective assessment tool which can give precise idea about vascular compromise. Flow 800 can serve as a valuable tool in this complex surgery.

Objective:

The objective of this study was to evaluate the utility of microscope-integrated fluorescent ICG videoangiography (Flow 800) in A-com aneurysm surgery.

Materials and Methods:

We used Flow 800 in ten consecutive patients of A-com aneurysm surgery from July 2019 to October 2019. We studied patient characteristics, intraoperative observation of ICG and Flow 800, and corresponding changes made in the operative decisions.

Results:

The use of Flow 800 helped in intraoperative decision of four out of ten patients of A-com aneurysm. In two patients, incomplete clipping was confirmed with Flow 800 and the second clip was applied. In the third patient, perforator compromise was found hence needed clip readjustment, whereas in the fourth patient, ICG was inconclusive and Flow 800 confirmed complete clipping of aneurysm.

Conclusion:

Flow 800 is a conclusive reproducible and objective tool for early detection of vascular compromise of multiple vessels and perforators in A-com aneurysm surgery. It gives a better idea of vasculature, especially where ICG is ambiguous or inconclusive.

Safety and Feasibility Assessment of the O-Arm as an Intraoperative Angiography Device in Aneurysm Surgery

OBJECTIVE

To describe the technique and initial experience of using a rotational 3-dimensional (3D) fluoroscopy system (O-arm; Medtronic) as intraoperative angiography (IA) in the surgery of cerebral aneurysms.

METHODS

The 3D IA with O-arm (IAWOA) was performed in a consecutive cohort of patients with unruptured intracranial aneurysms. Conventional microsurgical clipping was performed with the assistance of indocyanine green videoangiography. Then the O-arm chassis was brought in, the ipsilateral internal carotid artery was catheterized, and contrasted images were acquired. Resulting datasets were exported in Digital Imaging and Communications in Medicine and processed using the Osirix software in an accessory computer. The 3D image reconstruction was evaluated intraoperatively to confirm aneurysm occlusion and parent vessel patency. Afterward, agreement among IAWOA, indocyanine green videoangiography, and standard postoperative angiography was analyzed.

RESULTS

The initial pilot study was performed in 6 patients with 7 unruptured aneurysms. The aneurysm occlusion rate was 100%. The concordance of the IAWOA and the standard postoperative angiography was complete, both in terms of occlusion and parent vessel patency. No complications derived from the IAWOA were observed except in 1 patient, who presented a retroperitoneal hematoma without clinical consequences.

CONCLUSIONS

The 3D rotational fluoroscopy (O-arm) device could be safely and effectively used as an IA system in selected patients. To the best of our knowledge, this is the first study reporting its use as an IA device. This technique seems to offer excellent image quality that could be compared with that of the gold standard 3D digital subtraction angiography but with a lower cost and versatility of use for other subspecialties.

Early Intracranial Aneurysm Recurrence after Microsurgical Clip Ligation: Case Report and Review of the Literature

Microsurgical clip ligation is considered a definitive treatment for intracranial aneurysms (IAs), resulting in low rates of local recurrence that range from 0.2 to 0.5% and a latency period that averages about a decade. Our case report describes an early asymptomatic recurrence (i.e., without sentinel headache or seizure) less than 1 year after this 20-year-old woman underwent clip ligation of a ruptured anterior communicating artery (AComA) aneurysm. At recurrence, the patient underwent coiling of the regrowth; follow-up imaging at 6 and 18 months demonstrated complete IA occlusion. To review the putative risk factors of this rare phenomenon, the authors searched the PubMed database using the keywords "intracranial aneurysm," "recurrence," and "clipping" in various combinations. In the seven cases identified, all occurred in initially ruptured IA, which was often at the AComA, and six of seven patients were younger than 50 years old. Although most IA remnants grow slowly, early recurrence may represent a more aggressive biological behavior that warrants special attention in younger patients, positive rupture status, and unintended remnant of any size. In such a constellation, early imaging follow-up within the first 6 months may be warranted to rule out early IA recurrence.

Intraoperative Measurement of Arterial Blood Flow in Aneurysm Surgery

Intraoperative flowmetry (IF) has been recently introduced during cerebral aneurysm surgery in order to obtain a safer surgical exclusion of the aneurysm. This study evaluates the usefulness of IF during surgery for cerebral aneurysms and compares the results obtained in the joined surgical series of Verona and Padua to the more recent results obtained at the neurosurgical department of Verona.In the first surgical series, between 2001 and 2010, a total of 312 patients were submitted to IF during surgery for cerebral aneurysm at the neurosurgical departments of Verona and Padua: 162 patients presented with subarachnoid hemorrhage (SAH) whereas 150 patients harbored unruptured aneurysms. In the second series, between 2011 and 2016, 112 patients were submitted to IF during surgery for cerebral aneurysm at the neurosurgical department of Verona; 24 patients were admitted for SAH, whereas 88 patients were operated on for unruptured aneurysms.Comparison of the baseline values in the two surgical series and the baseline values between unruptured and ruptured aneurysms showed no statistical differences between the two clinical series. Analysis of flowmetry measurements showed three types of loco-regional flow derangements: hyperemia after temporary arterial occlusion, redistribution of flow in efferent vessels after clipping, and low flow in patients with SAH-related vasospasm.IF provides real-time data about flow derangements caused by surgical clipping of cerebral aneurysm, thus enabling the surgeon to obtain a safer exclusion; furthermore, it permits the evaluation of other effects of clipping on the loco-regional blood flow. It is suggested that-in contribution with intraoperative neurophysiological monitoring-IF may now constitute the most reliable tool for increasing safety in aneurysm surgery.

A pilot study on assessing the role of intra-operative Flow 800 vascular map model in predicting onset of vasospasm following micro vascular clipping of ruptured intracranial aneurysms

Objective To ascertain the predictive value of intra-operative FLOW 800 vascular map model in predicting onset of post-operative clinical vasospasm and delayed cerebral ischemia among patients undergoing micro-vascular clipping of ruptured intracranial aneurysms.  Material and methods A total of 40 patients were enrolled in the study and their variables such as age, World Federation of Neurological Surgeons (WFNS) grade at presentation, Computerized Tomography (CT) Fisher grading, location of the aneurysms, and Indocyanine Green (ICG) flow status were compared and statistically analyzed along with differences in Absorption Intensities (AI) and difference in time lag values obtained from the FLOW 800 vascular map studies for predicting onset of vasospasm.  Results The Receiver Operating curve (ROC) of the model for predicting post-operative vasospasm was highest (.892) for difference in the AI followed by CT Fisher grading (.778), difference in time lag (.700) and WFNS grading (.699).Analysis of variance for different variables studied in our model for predicting vasospasm was significant for all except for age (.991) and the ICG flow through the parent vessel (.079).Multivariate analysis done for predicting the vasospasm was significant for all variables except for age (.869) and ICG main flow (.196) Conclusion Our study confirmed the role of FLOW 800 study model in predicting clinical vasospasm. Inclusion of this entity would therefore help in taking timely and correct therapeutics measures to ensure better patient outcomes.

Intraoperative angiography via the popliteal artery: a useful technique for patients in the prone position

OBJECTIVE Intraoperative angiography can be a valuable tool in the surgical management of vascular disorders in the CNS. This is typically accomplished via femoral artery puncture; however, this can be technically difficult in patients in the prone position. The authors describe the feasibility of intraoperative angiography via the popliteal artery in the prone patient. METHODS Three patients underwent intraoperative spinal angiography in the prone position via vascular access through the popliteal artery. Standard angiography techniques were used, along with ultrasound and a micropuncture needle for initial vascular access. Two patients underwent intraoperative angiography to confirm the obliteration of dural arteriovenous fistulas. The third patient required unexpected intraoperative angiography when a tumor was concerning for a vascular malformation in the cervical spine. RESULTS All 3 patients tolerated the procedure without complication. The popliteal artery was easily accessed without any adaptation to typical patient positioning for these prone-position cases. This proved particularly beneficial when angiography was not part of the preoperative plan. CONCLUSIONS Intraoperative angiography via the popliteal artery is feasible and well tolerated. It presents significant benefit when obtaining imaging studies in patients in a prone position, with the added benefit of easy access, familiar anatomy, and low concern for catheter thrombosis or kinking.

The working road map in a neurosurgical Hybrid Angio-Surgical suite------ development and practice of a neurosurgical Hybrid Angio-Surgical suite

Background

The concept of a Hybrid Angio-Surgical Suite (HASS) has emerged as a solution to the complexity of cerebrovascular surgery and the need for immediate intraoperative feedback. When to use it, what cases are suitable for its use, who can use it and how to use it remain debatable.

Objective

Provide the information regarding the application of the HASS for hospital, neurosurgeon and interventionalist.

Methods

We review the literatures of case reports and studies on the use of the hybrid angio-sugical suite along with application of HASS in our own practice.

Results

Indications for using HASS on different types of cerebral vascular disease, including cerebral aneurysm, AVM, DAVF, carotid and vertebral stenosis/occlusion, are addressed. The application of HASS for other non-cerebral vascular diseases, such as trauma, spine and skullbase cases, is reviewed and discussed.

Conclusion

HASS has made many surgical procedures safer and many difficult or previously untreatable conditions much more tractable and cost-effective. Other than used in cerebral vascular disease, HASS has much more applications, such as trauma, spine and other neurosurgical diseases.

Angiographic and epidemiological characteristics associated with aneurysm remnants after microsurgical clipping

BACKGROUND

Despite new techniques for the treatment of cerebral aneurysms, the percentage of aneurysm remnants after surgical intervention seems to be relatively constant. The objective of this study was to assess angiographic and epidemiological features associated with aneurysm remnants after microsurgical clipping.

METHODS

This study was conducted from February 2009 to August 2012 on a series of 90 patients with 105 aneurysms referred to the Santa Casa of Belo Horizonte who were surgically treated and angiographically controlled.

RESULTS

Surgical clipping was considered incomplete in 13.3% of the aneurysms. The mean age of cases with an aneurysm remnant was 57.5 years, whereas the mean age without aneurysm remnant was 49.7 years (P = 0.02). Aneurysm remnants were detected more frequently on the internal carotid artery, nevertheless, no statistically significant differences were verified when comparing the locations. Aneurysm size in the preoperative angiography verified that the mean size of aneurysms operated was 6.56 mm, such that in cases showing a postoperative remnant, the mean size was 9.7 mm and in cases with complete clipping it was 6.08 mm (P = 0.02). Postoperative angiography showed that, in cases with residual aneurysm, the number of clips used was higher - a mean of 1.8 for complete clipping and 3.1 for incomplete clipping (P < 0.001).

CONCLUSIONS

Aneurysm size and patient age showed significant correlations with residual intracranial aneurysm. The mean number of clips used was higher in cases with incomplete occlusion.

Comparison of Efficacy of Intraoperative Indocyanine Green Videoangiography in Clipping of Anterior Circulation Aneurysms with Postoperative Digital Subtraction Angiography

Introduction:

The aim of this study is to assess the efficacy of intraoperative indocyanine green videoangiography (ICG-VA) using postoperative digital subtraction angiography (DSA) in clipped anterior circulation aneurysms.

Materials and Methods:

A prospective study was conducted for 1 year which included thirty patients of anterior circulation aneurysm treated by clipping of aneurysm. Intraoperative ICG-VA was performed on all the patients. Postoperative DSA was performed to assess the efficacy of ICG-VA.

Results:

Intraoperative ICG-VA revealed the occlusion of aneurysm in all the thirty patients. Postoperative DSA revealed aneurysm neck remnant in two patients and demonstrated no branch occlusion.

Conclusions:

Intraoperative ICG-VA is useful in assessing the completeness of clipping of cerebral aneurysms and ensures patency of branch vessels, thus providing a better postoperative outcome. It replaces the need for invasive postoperative angiographic imaging in a selected group of patients and is also cost effective.

Endoscopic Fluorescence Angiography with Indocyanine Green : A Preclinical Study in the Swine

OBJECTIVE

Microscopic indocyanine green (ICG) angiography is useful for identifying the completeness of aneurysm clipping and the preservation of parent arteries and small perforators. Neuroendoscopy is helpful for visualizing structures beyond the straight line of the microscopic view. We evaluated our prototype of endoscopic ICG fluorescence angiography in swine, which we developed in order to combine the merits of microscopic ICG angiography and endoscopy.

METHODS

Our endoscopic ICG system consists of a camera, a light source, a display and software. This system can simultaneously display real-time visible and near infrared fluorescence imaging on the same monitor. A commercially available endoscope was used, which was 4 mm in diameter and had an angle of 30°. A male crossbred swine was used.

RESULTS

Under general anesthesia, a small craniotomy was performed and the brain surface of the swine was exposed. ICG was injected via the ear vein with a bolus dose of 0.3 mg/kg. Visible and ICG fluorescence images of cortical vessels were simultaneously observed on the display monitor at high resolution. The real-time merging of the visible and fluorescent images corresponded well.

CONCLUSION

Simultaneous visible color and ICG fluorescent imaging of the cortical vessels in the swine brain was satisfactory. Technical improvement and clinical implication are expected.

Integration of indocyanine green videoangiography with operative microscope: augmented reality for interactive assessment of vascular structures and blood flow

BACKGROUND

Preservation of adequate blood flow and exclusion of flow from lesions are key concepts of vascular neurosurgery. Indocyanine green (ICG) fluorescence videoangiography is now widely used for the intraoperative assessment of vessel patency.

OBJECTIVE

Here, we present a proof-of-concept investigation of fluorescence angiography with augmented microscopy enhancement: real-time overlay of fluorescence videoangiography within the white light field of view of conventional operative microscopy.

METHODS

The femoral artery was exposed in 7 anesthetized rats. The dissection microscope was augmented to integrate real-time electronically processed near-infrared filtered images with conventional white light images seen through the standard oculars. This was accomplished by using an integrated organic light-emitting diode display to yield superimposition of white light and processed near-infrared images. ICG solution was injected into the jugular vein, and fluorescent femoral artery flow was observed.

RESULTS

Fluorescence angiography with augmented microscopy enhancement was able to detect ICG fluorescence in a small artery of interest. Fluorescence appeared as a bright-green signal in the ocular overlaid with the anatomic image and limited to the anatomic borders of the femoral artery and its branches. Surrounding anatomic structures were clearly visualized. Observation of ICG within the vessel lumens permitted visualization of the blood flow. Recorded video loops could be reviewed in an offline mode for more detailed assessment of the vasculature.

CONCLUSION

The overlay of fluorescence videoangiography within the field of view of the white light operative microscope allows real-time assessment of the blood flow within vessels during simultaneous surgical manipulation. This technique could improve intraoperative decision making during complex neurovascular procedures.

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.

Comparing routine versus selective use of intraoperative cerebral angiography in aneurysm surgery: a prospective study

INTRODUCTION

While the use of intraoperative angiography (IA) has been shown to be a useful adjunct in aneurysm surgery, its routine use remains controversial.

OBJECTIVE

We wished to determine if IA is required in all patients undergoing aneurysm surgery (ie, routine IA) or if intraoperative assessment can reliably predict the need for IA (ie, select IA).

METHODS

We prospectively evaluated all patients undergoing craniotomy for aneurysm clipping. In these patients, the treating surgeons were asked to record whether they felt IA was required at two time points: (1) prior to surgery and (2) immediately after clip application but before IA. All patients underwent IA as per the institutional protocol. IA results and the need for post-IA clip adjustments were recorded.

RESULTS

Of the 200 patients enrolled, 197 were included for analysis. IA was deemed necessary on preoperative assessment in 144 cases (73%) and on post-clip assessment in 116 cases (59%). Post-clip IA demonstrated 47 (24%) positive findings and post-IA clip adjustments were made in 19 of 198 cases (10%). On preoperative assessment, there were four cases where IA was deemed unnecessary, yet post-IA clip adjustment was required, resulting in a sensitivity of 79% and false negative rate of 8%. Regarding post-clip assessment, there were five cases where IA was thought to be unnecessary and clip adjustment was required, resulting in a sensitivity of 73% and false negative rate of 6%.

CONCLUSIONS

The accuracy of a strategy of select IA was not improved by assessing the need for IA immediately after aneurysm clipping versus prior to surgery onset. This suggests that intraoperative assessment regarding the adequacy of aneurysm clip application should be viewed with caution.

Intraoperative cerebral angiography in arteriovenous malformation resection in children: a single institutional experience

OBJECT

The use of cerebral intraoperative angiography has been described in resection of arteriovenous malformations (AVMs) in adults. More recently, studies have described experiences with intraoperative angiography in a small number of children. However, data on the safety and clinical utility of intraoperative angiography in the pediatric population remains limited in comparison with available data in adults. The aim of the study was to evaluate the use of cerebral intraoperative angiography in children undergoing AVM resection. The clinical utility of intraoperative angiography and procedure-related complications were evaluated.

METHODS

A retrospective review was performed for all patients undergoing cerebral AVM resection with intraoperative angiography at The Children's Hospital of Philadelphia between 2008 and 2012. Patient imaging and operative and medical notes were reviewed to evaluate for end points of the study. A total of 17 patients (8 males, 9 females) were identified, with a median age of 12.1 years (range 1.2-17.9 years) and median weight of 45.5 kg (range 12.1-78.9 kg).

RESULTS

A total of 21 intraoperative angiography procedures were performed for 18 AVM resections in 17 patients. The technical success rate was 94%. In 2 cases (11%), intraoperative angiography demonstrated a residual AVM, and repeat resections were performed. In both cases, no recurrent disease was noted on postoperative follow-up. One procedure-related complication (4.8%) occurred in 1 patient who was positioned prone. Recurrence to date was noted in 2 (14%) of the 14 cases with available postoperative follow-up at 3.5 and 4.7 months following resection with intraoperative angiography. The median follow-up time from intraoperative angiography to the most recent postoperative angiography was 1.1 years (range 4.3 months to 3.8 years).

CONCLUSIONS

Intraoperative angiography is an effective and safe adjunct for surgical management of cerebral AVMs in the pediatric population.

Use of indocyanine green videoangiography during intracranial aneurysm surgery reduces the incidence of postoperative ischaemic complications

Microscope-integrated near-infrared indocyanine green videoangiography (ICGVA) has been shown to be a useful adjunct for intracranial aneurysm surgery. That the routine application of this technique reduces the risk of postoperative ischaemic complication, however, has not been reported. We present a retrospective matched-pair comparison of ICGVA guided aneurysm surgery versus historic control surgical cohort treated by the same author. Index patients and controls were matched for aneurysm size, location, patient demographics, risk factors, comorbidities, and surgical treatments. Ninety-one eligible patients with 100 intracranial aneurysms were treated using ICGVA assistance. There were no statistically significant differences between the two groups in terms of patient age, sex, risk factors, comorbidities and aneurysm characteristics. Of the 100 aneurysms in the ICGVA group, 107 investigations of ICGVA were performed. In 79 aneurysms (79.0%), ICGVA was considered useful but did not affect surgical management. In six patients (6.0%), ICGVA led to a crucial change of intraoperative strategies. In nine patients (9.0%), it was considered critical in assuring patency of small perforators. ICGVA was of no benefit in four patients (4.0%) and was misleading in two (2.0%). Postoperative ischaemic complications occurred in three patients (3.3%) in the ICGVA group compared with seven patients (7.7%) in the control group (p<0.001). Our study supports the use of ICGVA in aneurysm surgery as a safe and effective modality of intraoperative blood flow assessment. With all limitations of a retrospective matched-pair comparison, the use of ICGVA during routine aneurysm surgery reduces the incidence of postoperative ischaemic complications.

Value of indocyanine green videoangiography in deciding the completeness of cerebrovascular surgery

OBJECTIVE

Recently, microscope-integrated near infrared indocyanine green videoangiography (ICG-VA) has been widely used in cerebrovascular surgery because it provides real-time high resolution images. In our study, we evaluate the efficacy of intraoperative ICG-VA during cerebrovascular surgery.

METHODS

Between August 2011 and April 2012, 188 patients with cerebrovascular disease were surgically treated in our institution. We used ICG-VA in that operations with half of recommended dose (0.2 to 0.3 mg/kg). Postoperative digital subtraction angiography and computed tomography angiography was used to confirm anatomical results.

RESULTS

Intraoperative ICG-VA demonstrated fully occluded aneurysm sack, no neck remnant, and without vessel compromise in 119 cases (93.7%) of 127 aneurysms. Eight clipping (6.3%) of 127 operations were identified as an incomplete aneurysm occlusion or compromising vessel after ICG-VA. In 41 (97.6%) of 42 patients after carotid endarterectomy, the results were the same as that of postoperative angiography with good patency. One case (5.9%) of 17 bypass surgeries was identified as a nonfunctioning anastomosis after ICG-VA, which could be revised successfully. In the two patients of arteriovenous malformation, ICG-VA was useful for find the superficial nature of the feeding arteries and draining veins.

CONCLUSION

ICG-VA is simple and provides real-time information of the patency of vessels including very small perforators within the field of the microscope and has a lower rate of adverse reactions. However, ICG-VA is not a perfect method, and so a combination of monitoring tools assures the quality of cerebrovascular surgery.

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.

Endoscopy in aneurysm surgery

BACKGROUND

Surgical clipping with complete occlusion of the aneurysm and preservation of parent, branching, and perforating vessels remains the most definitive treatment for intracranial aneurysms.

OBJECTIVE

To evaluate the benefit of endoscopic application during microsurgical procedures in a retrospective study.

METHODS

One hundred eighty aneurysms were microsurgically treated in 124 operations. Three different applications of endoscopic visualization were used, depending on the respective requirements: inspection before clipping, clipping under endoscopic view, and postclipping evaluation.

RESULTS

Of 1380 aneurysms, 292 procedures were done with application of the endoscope. Of these 292, a complete data set, including video recording of the procedures for retrospective evaluation, was available in 180 cases. In these, the endoscope provided a favorable enhancement of the visual field, particularly in complex or deep-seated lesions. No adverse effects were observed. Before clipping, the endoscope was used to gain additional topographic information in 150 of 180 cases (83%). Clipping under endoscopic view was performed in 4 cases. After clipping, endoscopic inspection was performed in 130 of 180 procedures. Depending on the endoscopic findings, rearrangement of the applied clip or additional clipping was found to be necessary in 26 of 130 cases (20.0%).

CONCLUSION

Endoscopic enhancement of the visual field provided by the endoscope before, during, and after microsurgical aneurysm occlusion may be a safe and effective application to increase the quality of treatment. Although unexpected findings concerning completeness of aneurysm occlusion and compromise of involved vessels could be diminished by endoscopic assessment, total prevention was not accomplished.

The concept of a hybrid operating room: applications in cerebrovascular surgery

The use of intraoperative digital substraction angiography (iDSA) is a tool in cerebrovascular surgery. According to recent studies, iDSA has been shown to alter surgical treatment in approximately 12% of cases. Moreover, it has been demonstrated that even experienced cerebrovascular surgeons might not accurately predict the need for iDSA. Intraoperative DSA prevents unnecessary surgical manipulations after occlusion of aneurysms and accurately demonstrates occlusion rates. We present our preliminary experience using routine iDSA within the concept of a hybrid operating room for cerebrovascular surgery. A total of 99 patients underwent iDSA in our hybrid operating room. Indications included intraoperative evaluation of occlusion rate of clipped aneurysms and patency of vicinity vessels (n = 82), chemical angioplasty with papaverin (n = 4), and balloon angioplasty (n = 1). In four (5%) patients, a reposition of the clip was needed due to neck remnant and perfusion of the aneurysm sack after clipping. A total of five cases underwent combined microsurgical and endovascular treatment of ruptured aneurysms and arteriovenous malformations (AVMs). The concept of a hybrid operating room has been considered in the planning and design of operation rooms dedicated to cerebrovascular surgery. Hybrid procedures combining endovascular with microsurgical strategies within the same surgical session are feasible and safe. These procedures are associated with cost-benefit advantages.

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.

Near-infrared indocyanine green videoangiography (ICGVA) and intraoperative computed tomography (iCT): are they complementary or competitive imaging techniques in aneurysm surgery?

BACKGROUND

In this pilot study we compared advantages and drawbacks of near-infrared indocyanine green videoangiography (ICGVA) and intraoperative computed tomography (iCT) to investigate if these are complementary or competitive methods to acquire immediate information about blood vessels and potential critical impairment of brain perfusion during vascular neurosurgery.

METHODS

A small subset of patients (n = 10) were prospectively enrolled in this feasibility study and received ICGVA immediately after placement of the aneurysm clips. An intraoperative cranial CT angiography (iCTA) was followed by dynamic perfusion CT scan (iCTP) using a 40-slice, sliding-gantry, CT scanner. The vascular patency of major (aneurysm bearing) arteries, visualisation of arising perforating arteries and brain perfusion after clip application were analysed with both techniques.

RESULTS

The ICGVA was able to visualise blood flow and vascular patency of all major vessels and perforating arteries within the visual field of the microscope, but failed to display vessels located within deeper areas of the surgical field. Even small coverage with brain parenchyma impaired detection of vessels. With iCTA high image quality could be obtained in 7/10 cases of clipped aneurysms. Intraoperative CTA was not sufficiently evaluable in one PICA aneurysm and one case of a previously coiled recurrent aneurysm, due to extensive coil artefacts. Small, perforating arteries could not be detected with iCTA. Intraoperative CTP allowed the assessment of global blood flow and brain perfusion in sufficient quality in 5/10 cases, and enabled adequate intraoperative decision making.

CONCLUSION

A combination of ICGVA and iCT is feasible, with very good diagnostic imaging quality associated with short acquisition time and little interference with the surgical workflow. Both techniques are complementary rather than competing analysing tools and help to assess information about local (ICGVA/iCTA) as well as regional (iCTA/iCTP) blood flow and cerebral perfusion immediately after clipping of intracranial aneurysms.

Safety and Efficacy of Intraoperative Angiography in Craniotomies for Cerebral Aneurysms and Arteriovenous Malformations

BACKGROUND:

In an era of indocyanine angiography, the routine use of intraoperative angiography (IOA) in the surgical treatment of aneurysms and vascular malformations is controversial.

OBJECTIVE:

To retrospectively assess the safety and efficacy of IOA and to determine predictors of surgical revision.

METHODS:

Between 2003 and 2011, IOA was performed during surgical treatment of 976 aneurysms, 101 arteriovenous malformations (AVMs), and 16 arteriovenous fistulas.

RESULTS:

In 80 of 976 aneurysms (8.2%), IOA prompted clip repositioning. The reason for readjustment was residual aneurysm in 54.7%, parent vessel occlusion in 42.9%, and both in 2.4% of cases. In multivariate analysis, increasing aneurysm size (P &lt; .001), ruptured aneurysm (P &lt; .001), and increasing number of vessels injected (P &lt; .001) were strong predictors of clip readjustment. There was a strong trend for posterior circulation aneurysm location to predict clip repositioning (P = .06). IOA revealed residual nidus/fistula requiring further intervention in 9 of 101 AVMs (8.9%) and 3 of 16 arteriovenous fistulas (18.8%). Of 9 AVMs requiring a surgical revision, 2 (22.2%) were Spetzler-Martin grade II, 5 (55.6%) were grade III, and 2 (22.2%) were grade IV. Mean Spetzler-Martin grade was 3.0 in AVMs requiring surgical revision compared with 2.3 in those not requiring revision (P = .05). IOA-related complications were all transient or minor and occurred in 0.99% of patients; none resulted in permanent morbidity.

CONCLUSION:

IOA remains a valuable tool in the surgical treatment of brain vascular abnormalities, guiding surgical re-exploration in &gt; 8% of cases. Easy access to an angiographer and routine use of IOA are important factors contributing to procedural safety and efficacy.

Endoscope-integrated ICG technology: first application during intracranial aneurysm surgery

Microscopic indocyanine green videoangiography (mICG-VA) has gained wide acceptance during intracranial aneurysm surgery by lowering rates of incomplete clipping and occlusion of surrounding vessels. However, mICG-VA images are limited to the microscopic view and some deeper areas, including the aneurysm sac/neck posterior side, cannot be efficiently assessed as they are hidden by the aneurysm, clips, or surrounding structures. Contrarily, endoscopes allow a wider area of visualization, but neurosurgical endoscopes to date only provided visual data. We describe the first application of endoscope ICG-integrated technology (eICG) applied in an initial case of anterior communicating artery aneurysm clipping. This new technique provided also relevant information regarding aneurysm occlusion and patency of parent and branching vessels and small perforating arteries. eICG-VA provided additional information compared to mICG-VA by magnifying areas of interest and improving the ability to view less accessible regions, especially posterior to the aneurysm clip. Obtaining eICG sequences required currently the microscope to be moved away from the operating field. eICG-VA was only recorded under infrared illumination which prevented tissue handling, but white-infrared light views could be interchanged instantaneously. Further development of angled endoscopes integrating the ICG technology and dedicated filters blocking the microscopic light could improve visualization capacities even further. In conclusion, as a result of its ability to reveal structures around corners, the eICG-VA technology could be beneficial when used in combination with mICG-VA to visualize and confirm vessel patency in areas that were previously hidden from the microscope.

The role of intraoperative micro-Doppler ultrasound in verifying proper clip placement in intracranial aneurysm surgery

INTRODUCTION

Aneurysmal subarachnoid hemorrhage constitutes a clinical entity associated with high mortality and morbidity. It is widely accepted that improper clip placement may have as a result of incomplete aneurysm occlusion and/or partial or complete obstruction of an adjacent vessel. Various modalities, including intraoperative or postoperative digital subtracting angiography, near-infrared indocyanine green angiography, micro-Doppler ultrasonography (MDU), and neurophysiological studies, have been utilized for verifying proper clip placement. The aim of our study was to review the role of MDU during aneurysmal surgery.

METHODS

A literature search was performed using any possible combination of the following terms: "aneurysm," "brain," "cerebral," "clip," "clipping," "clip malpositioning," "clip repositioning," "clip suboptimal positioning," "Doppler," "intracranial," "microsurgery," "micro-Doppler," "residual neck," "ultrasonography," "ultrasound," and "vessel occlusion". Additionally, reference lists from the retrieved articles were reviewed for identifying any additional articles. Case reports and miniseries were excluded.

RESULTS

A total of 19 series employing intraoperative MDU during aneurysmal microsurgery were retrieved. All studies demonstrated that MDU accuracy is extremely high. The highest reported false-positive rate of MDU was 2 %, while the false-negative rate was reported as high as 1.6 %. It has been demonstrated that the presence of subarachnoid hemorrhage, specific anatomic locations, and large size may predispose to improper clip placement. Intraoperative MDU's technical limitations and weaknesses are adequately identified, in order to minimize the possibility of any misinterpretations.

CONCLUSION

Intraoperative MDU constitutes a safe, accurate, and low cost imaging modality for evaluating blood flow and for verifying proper clip placement during microsurgical clipping.

Monitoring techniques for prevention of procedure-related ischemic damage in aneurysm surgery

OBJECTIVE

To describe the application of intraoperative monitoring techniques during aneurysm surgery and to discuss the advantages and limitations of these techniques in prevention of postoperative neurologic deficits.

METHODS

Articles found in the literature through PubMed for the time frame 1980-2011 and the authors' personal files were reviewed.

RESULTS

Various techniques for detection of vascular insufficiency are available, including direct methods to measure cerebral blood flow and indirect methods to evaluate the integrity of neurologic pathways.

CONCLUSIONS

The choice of monitoring modality should be governed by the vessel and by the vascular territory most at risk during the planned procedure with proper awareness of the potential limits related to each technique. Aneurysm surgery monitoring should help to address issues of continuity and provide a morphologic and functional assessment. Although the use of monitoring devices is still not routine in aneurysm surgery and no standards have been established, combining different monitoring techniques is crucial to optimize aneurysm surgery and avoid or minimize complications.

Measurement of Cortical Microcirculation During Intracranial Aneurysm Surgery by Combined Laser-Doppler Flowmetry and Photospectrometry

BACKGROUND:

Accidental vessel occlusion is one major risk of intracranial aneurysm surgery potentially causing cerebral ischemia. The intraoperative assessment of cerebral ischemia remains a technological challenge.

OBJECTIVE:

As a novel approach, cortical tissue integrity was monitored using simultaneous measurements of regional capillary-venous cerebral blood flow (rvCBF), oxygen saturation (Srvo2), and hemoglobin amount (rvHb) during aneurysm surgery.

METHODS:

Fifteen patients scheduled for aneurysm surgery of the anterior and posterior circulation were included. A fiber optic probe was placed on the cortex associated with the distal branch of the aneurysmatic vessel. Blinded measurements by combined laser-Doppler flowmetry (rvCBF) and photospectrometry (Srvo2, rvHb) were performed before and after surgical clipping or trapping of the aneurysm. Data were correlated with postoperative imaging and neurological outcome.

RESULTS:

Cortical measurements could be successfully performed in all patients. Significant increase (&gt;25% change from baseline) or decrease (&lt;25% change from baseline) of rvCBF, Srvo2, and rvHb was detectable in 33 to 46% of patients after surgical intervention. Severe decrease (&gt;50% change from baseline) of all parameters or solitary of rvCBF was correlated to reduced cerebral perfusion and neurological deficits in 2 patients.

CONCLUSION:

Combined laser-Doppler flowmetry and photospectrometry provides real-time information on cortical microcirculation. Intraoperative alterations of parameters (rvCBF, Srvo2, rvHb) might reflect changes of cerebral tissue integrity during intracranial aneurysm surgery.

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.

A review of the management of posterior communicating artery aneurysms in the modern era

Background:

Technical advancements have significantly improved surgical and endovascular treatment of cerebral aneurysms. In this paper, we review the literature with regard to treatment of one of the most common intra-cranial aneurysms encountered by neurosurgeons and interventional radiologists.

Conclusions:

Anterior clinoidectomy, temporary clipping, adenosine-induced cardiac arrest, and intraoperative angiography are useful adjuncts during surgical clipping of these aneurysms. Coil embolization is also an effective treatment alternative particularly in the elderly population. However, coiled posterior communicating artery aneurysms have a particularly high risk of recurrence and must be followed closely. Posterior communicating artery aneurysms with an elongated fundus, true posterior communicating artery aneurysms, and aneurysms associated with a fetal posterior communicating artery may have better outcome with surgical clipping in terms of completeness of occlusion and preservation of the posterior communicating artery. However, as endovascular technology improves, endovascular treatment of posterior communicating artery aneurysms may become equivalent or preferable in the near future. One in five patients with a posterior communicating artery aneurysm present with occulomotor nerve palsy with or without subarachnoid hemorrhage. Factors associated with a higher likelihood of recovery include time to treatment, partial third nerve deficit, and presence of subarachnoid hemorrhage. Both surgical and endovascular therapy offer a reasonable chance of recovery. Based on level 2 evidence, clipping appears to offer a higher chance of occulomotor nerve palsy recovery; however, coiling will remain as an option particularly in elderly patients or patients with significant comorbidity.

Intraoperative Doppler and Duplex sonography in cerebral aneurysm surgery

PURPOSE

The aim of open surgery of cerebral aneurysms is to minimise the risk of infarction due to poor position of a clip while still securing the aneurysm from rebleeding. Whilst digital subtraction angiography (DSA) remains the gold standard for precise evaluation of the result, its invasiveness, risk of thromboembolic infarction, availability and time-consumption pose a significant limitation, and overall it is rarely used. The goal of the present study was to analyse the feasibility of intraoperative B-mode Duplex ultrasound in combination with Doppler sonography (DDS) to evaluate this issue.

METHODS

A total of 44 aneurysms in 40 patients were investigated intraoperatively via B-mode and power Duplex sonography after clip positioning in a prospective setting. Data were then compared to postoperative angiography.

RESULTS

In 38 cases DDS allowed for visualisation of aneurysm localisation, neck and diameter, as well as associated vessels, in accordance to preoperative DSA. This was confirmed by Duplex sonography in 94.7%. Further evaluation of each associated vessel after clip positioning was then enabled by Doppler sonography in 84.8%. Visualisation in terms of B-mode sonography was not successful in six cases due to multiple clips.

CONCLUSION

DDS is an additional tool for immediate evaluation of clipping performance intraoperatively and can be used in simple cases with reliable results. In six cases Doppler-/Duplex-sonography did not illustrate the clipping result sufficiently. It is not yet able to replace DSA in aneurysms with complex configuration.