Novel System of Simulation Models for Aneurysm Clipping Training: Description of Models and Assessment of Face, Content, and Construct Validity.

BACKGROUND: Aneurysm clipping simulation models are needed to provide tactile feedback of biological vessels in a nonhazardous but surgically relevant environment. OBJECTIVE: To describe a novel system of simulation models for aneurysm clipping training and assess its validity. METHODS: Craniotomy models were fabricated to mimic actual tissues and movement restrictions experienced during actual surgery. Turkey wing vessels were used to create aneurysm models with patient-specific geometry. Three simulation models (middle cerebral artery aneurysm clipping via a pterional approach, anterior cerebral artery aneurysm clipping via an interhemispheric approach, and basilar artery aneurysm clipping via an orbitozygomatic pretemporal approach) were subjected to face, content, and construct validity assessments by experienced neurosurgeons (n = 8) and neurosurgery trainees (n = 8). RESULTS: Most participants scored the model as replicating actual aneurysm clipping well and scored the difficulty of clipping as being comparable to that of real surgery, confirming face validity. Most participants responded that the model could improve clip-applier-handling skills when working with patients, which confirms content validity. Experienced neurosurgeons performed significantly better than trainees on all 3 models based on subjective (P = .003) and objective (P < .01) ratings and on time to complete the task (P = .04), which confirms construct validity. Simulations were used to discuss clip application strategies and compare them to prototype clinical cases. CONCLUSION: This novel aneurysm clipping model can be used safely outside the wet laboratory; it has high face, content, and construct validity; and it can be an effective training tool for microneurosurgery training during aneurysm surgery courses.

Assessment of Arterial Configurations of the Suprachiasmatic Region from the Endoscopic Endonasal Perspective: A Cadaveric Anatomical Study.

BACKGROUND: Endoscopic endonasal surgery has proved to offer a practical route to treat suprasellar lesions, including tumors and vascular pathologies. Understanding the different configurations of the anterior cerebral communicating artery (ACoA) complex (ACoA-C) is crucial to properly navigate the suprachiasmatic space and decrease any vascular injury while approaching this region through an endonasal approach. METHODS: An endoscopic endonasal transplanum-transtubercular approach was performed on 36 cadaveric heads (72 sides). The variations of the ACoA-C and feasibility of reaching its different components were analyzed. The surgical area exposure of the lamina terminalis was also quantified before and after mobilization of the ACoA-C. RESULTS: The typical ACoA-C configuration was found in 41.6% of specimens. The following 2 main variations were identified: accessory anterior cerebral artery segment 2 (5, 13.9%) and common trunk of anterior cerebral artery with absence of ACoA (5, 13.9%). Of 101 recurrent arteries of Heubner, 96 (95.0%) were identified within 4 mm proximal or distal to the ACoA. The mean lamina terminalis exposure area was 33.1 ± 16.7 mm2, which increased to 59.9 ± 11.9 mm2 after elevating the ACoA. CONCLUSIONS: A considerable amount of variation of the ACoA-C can be found through an endoscopic endonasal transplanum-transtubercular approach. These configurations determine the feasibility of lamina terminalis exposure and the complexity of reaching the ACoA. Assessment of ACoA morphology and its adjacent structures is crucial while approaching the suprachiasmatic through a transnasal corridor.

Mechanical thrombectomy for acute ischemic stroke in the posterior circulation: assessment of efficacy and outcome and identification of prognostic factors.

BACKGROUND: Mechanical thrombectomy (MT) is well-established in the treatment of acute ischemic anterior circulation stroke. However, there is no evidence from randomized trials or meta-analyses that MT is safe and effective in the treatment of patients with acute ischemic posterior circulation stroke (PCS). PURPOSE: To evaluate the clinical and procedural factors associated with recanalization and outcome of patients with PCS treated with MT. MATERIAL AND METHODS: Forty-three patients with PCS (median age 73 years) who underwent treatment with MT were included. Data including demographics, baseline stroke severity, radiological imaging, procedure and post-procedure complications were documented. Clinical outcome was evaluated using the modified Rankin Scale (mRS). The patients were classified into two groups based on clinical outcome (favorable vs. unfavorable mRS after 90 days). RESULTS: Median baseline National Institute of Health Stroke Scale (NIHSS) was 17. Twenty patients were eligible for intravenous thrombolysis and received recombinant tissue plasminogen activator before MT. Successful recanalization was observed in 88.4% of patients. After 90 days, favorable outcome (defined as mRS 0-2) was achieved in 26 patients; six patients had an unfavorable outcome (mRs >2). Final mortality rate was 25.5%. Baseline NIHSS, onset to reperfusion time, procedure duration, and successful recanalization had a statistically significant association with outcome. Failed recanalization and occurrence of intracranial hemorrhage were found to be associated with a higher mortality rate. CONCLUSION: MT is feasible and effective method in treatment of PCS. Baseline NIHSS and onset to reperfusion time were found to be independent predictive factors of clinical outcome.

Cost benefits of rapid recanalization using intraarterial thrombectomy.

OBJECTIVES: Thrombolytic therapy is associated with favorable clinical outcomes after successful and rapid recanalization in patients with acute ischemic stroke. This study aimed to evaluate the cost benefits and clinical outcomes at 1 year after intraarterial thrombectomy (IAT) by the rapidity of the successful recanalization. MATERIALS & METHODS: Clinical outcomes of and medical costs incurred by 230 patients with acute ischemic stroke who underwent IAT were compared by the rapidity from symptom onset to successful recanalization (2b/3 thrombolysis in cerebral infarction grade): ≤6-hr (n = 143), >6-hr (n = 31), and no-recanalization (n = 56). Clinical outcomes including functional independence (0-2 modified Rankin Score), mortality, and home-discharge checked at 1 year post-IAT were compared among the three groups. Cost utility was calculated using quality-adjusted life years (QALY) estimated using the EuroQol-5 dimensions-3 levels questionnaire and the fees paid for institutional rehabilitation during the year post-IAT, and, was compared among the groups. RESULTS: Patients in the ≤6-hr group showed higher functional independence (≤6-hr, 70%; >6-hr, 40%; no-recanalization, 6%, p < .001) and home-discharge rate (73%, 52%, 21%, and respectively, p < .001), and lower mortality (10%, 16%, and 43%, respectively, p < .001) at 1 year after IAT than other two groups. The cost utility of the ≤6-hr group was $35,557/QALY higher than that of the >6-hr group, and $27.829/QALY higher than no-recanalization group. CONCLUSIONS: Rapid and successful recanalization of the occluded intracranial vessels within 6 hr after the onset of symptoms resulted in markedly higher cost utility and functional independence at 1 year post-IAT.

The Utility of Dual-Energy Computed Tomographic Angiography for the Evaluation of Brain Aneurysms After Surgical Clipping: A Prospective Study.

OBJECTIVE: The purpose of this prospective study was to compare a novel dual-energy computed tomographic angiography (DECTA) method for postoperative assessment of clipped brain aneurysms to detect aneurysm remnants and parent artery patency, with catheter-based digital subtraction angiography (DSA). METHODS: Patients who underwent microsurgical cerebral aneurysm repair were prospectively evaluated after surgery by both DECTA and conventional DSA. CTA was performed using a novel dual-energy method with single source and fast kilovoltage switching (Gemstone Spectral Imaging [GSI]). DSA was performed using biplanar cerebral angiography. An experienced neuroradiologist and a neurosurgeon, both blinded to the original radiologic results, reviewed the images. RESULTS: On DSA, 8 of 15 aneurysms (53%) had a remnant after clipping. All of these remnants were <2 mm except for 1. The only residual aneurysm >2 mm was clearly detected by GSI CTA. Of those 7 DSA-confirmed <2-mm remnants, 5 were detected by GSI CTA. Metal artifacts compromised the image quality in 2 patients. The sensitivity and specificity of GSI CTA for remnant aneurysm <2-mm detection in single clip-treated patients were 100%. In all patients, these were 71.4 % and 100%, respectively. GSI CTA was 100% sensitive and 77% specific to detect parent vessel compromise, with associated positive and negative predictive values of 60% and 100%, respectively. CONCLUSIONS: DECTA is a promising noninvasive alternative to conventional catheter-based angiography for identification of aneurysm remnants and assessment of adjacent arteries after surgical clipping of brain aneurysms treated by 2 or fewer clips. It allows for a more rapid image acquisition than DSA, is more cost effective, and is widely available at clinical centers.

Assessment of extracranial-intracranial bypass in Moyamoya disease using 3T time-of-flight MR angiography: comparison with CT angiography.

BACKGROUND: To evaluate the value of time-of-flight MR angiography (TOF MRA) for the assessment of extracranial-intracranial (EC-IC) bypass in Moyamoya disease in comparison with computed tomography angiography (CTA). PATIENTS AND METHODS: A consecutive series of 23 patients with Moyamoya disease were analyzed retrospectively. Twenty three patients underwent 25 procedures of extracranial-intracranial bypass. Cranial CTA was performed within one week after the surgery to assess bypass patency. Then TOF MRA was scanned within 24 h after CTA on a 3T MRI system. Using 5-point scales (0 = poor to 4 = excellent), two radiologists rated the image quality and vessel integrity of bypass for three segments (extracranial, trepanation, intracranial). RESULTS: Image quality was high in both CTA and TOF MRA (mean quality score 3.84 ± 0.37 and 3.8 ± 0.41), without statistical difference (p = 0.66). Mean scores of TOF MRA with respect to bypass visualization were higher than CTA in the intracranial segment (p = 0.026). No significant difference of bypass visualization regarding the extracranial and trepanation segments was found between TOF MRA and CTA (p = 0.66 and p = 0.34, respectively). For the trepanation segment, TOF MRA showed pseudo lesions in 2 of all 25 cases. CONCLUSIONS: 3T TOF MRA, a non-contrast technique not exposing the patients to radiation, proved to be at least equal to CTA for the assessment of EC-IC bypass, and even superior to CTA with respect to the intracranial segment. In addition, readers should be aware of a potential overestimation showing focal pseudo lesions of the bypass at the trepanation segment in TOF MRA.

Vertebral artery-to-vertebral artery bypass with interposed radial artery or occipital artery grafts: surgical technique and report of three cases.

BACKGROUND: The treatment of unclippable vertebral artery (VA) aneurysms incorporating the posterior inferior cerebellar artery with parent artery preservation is among one of the most formidable challenges for cerebrovascular microsurgery and endovascular surgery. We propose that intracranial VA reconstruction using an extracranial VA-to-intracranial VA (VA-VA) bypass with a radial artery graft or an occipital artery graft may be an additional technique in the armamentarium to treat these formidable lesions. The rationale, surgical technique, and complications are discussed. METHODS: Three illustrative cases are described, in which the lesions were a VA dissecting aneurysm with ischemic lesions, bilateral asymptomatic unruptured VA aneurysms, and a VA giant aneurysm with subarachnoid hemorrhage. RESULTS: The partial extreme lateral infrajugular transcondylar approach was used. Computed tomographic angiography was useful for preoperative evaluation of the depth of the distal aneurysmal neck. A VA-VA bypass was performed in two patients. Because there was another ipsilateral aneurysm at the V2 segment in one patient, an external carotid artery-VA bypass was performed. Although two patients were discharged with good clinical results, one patient with subarachnoid hemorrhage died because of brainstem infarction. CONCLUSIONS: The VA-VA bypass using a radial artery graft or an occipital artery graft is an option that can be considered in the strategy for treating VA aneurysms to preserve the normal anatomic vascular configuration in the posterior circulation.

Microscope-integrated quantitative analysis of intraoperative indocyanine green fluorescence angiography for blood flow assessment: first experience in 30 patients.

BACKGROUND: Intraoperative measurements of cerebral blood flow are of interest during vascular neurosurgery. Near-infrared indocyanine green (ICG) fluorescence angiography was introduced for visualizing vessel patency intraoperatively. However, quantitative information has not been available. OBJECTIVE: To report our experience with a microscope with an integrated dynamic ICG fluorescence analysis system supplying semiquantitative information on blood flow. METHODS: We recorded ICG fluorescence curves of cortex and cerebral vessels using software integrated into the surgical microscope (Flow 800 software; Zeiss Pentero) in 30 patients undergoing surgery for different pathologies. The following hemodynamic parameters were assessed: maximum intensity, rise time, time to peak, time to half-maximal fluorescence, cerebral blood flow index, and transit times from arteries to cortex. RESULTS: For patients without obvious perfusion deficit, maximum fluorescence intensity was 177.7 arbitrary intensity units (AIs; 5-mg ICG bolus), mean rise time was 5.2 seconds (range, 2.9-8.2 seconds; SD, 1.3 seconds), mean time to peak was 9.4 seconds (range, 4.9-15.2 seconds; SD, 2.5 seconds), mean cerebral blood flow index was 38.6 AI/s (range, 13.5-180.6 AI/s; SD, 36.9 seconds), and mean transit time was 1.5 seconds (range, 360 milliseconds-3 seconds; SD, 0.73 seconds). For 3 patients with impaired cerebral perfusion, time to peak, rise time, and transit time between arteries and cortex were markedly prolonged (>20, >9 , and >5 seconds). In single patients, the degree of perfusion impairment could be quantified by the cerebral blood flow index ratios between normal and ischemic tissue. Transit times also reflected blood flow perturbations in arteriovenous fistulas. CONCLUSION: Quantification of ICG-based fluorescence angiography appears to be useful for intraoperative monitoring of arterial patency and regional cerebral blood flow.

Draft formal response to Agency for Healthcare Research and Quality (AHRQ) Technical Brief on neurothrombectomy devices in acute ischemic stroke.

In the current environment of health policy reform, physicians must increasingly engage the federal system to inform the government regarding the state of the science and to advocate on behalf of their patients for the continued provision of necessary care. The Agency of Health Research and Quality (AHRQ), within the Department of Health and Human Services (DHHS), provides scientific advice to the Centers for Medicare and Medicaid Services (CMS) regarding the efficacy and cost-effectiveness of existing therapeutic modalities. These Technical Briefs provide the scientific basis for Medicare reimbursement policies. Recently, the AHRQ produced a Draft Technical Brief on Mechanical Thrombectomy for Acute Ischemic Stroke. This document potentially endangers future reimbursement for endovascular stroke care. The link to the Technical Brief is: http://effectivehealthcare.ahrq.gov/index.cfm/research-available-forcomment/comment-draftreports/?pageactiondisplaydraftcommentform&topicid161&productid418&documenttypedraftReport. The endovascular neurosurgery group at the University of Buffalo produced a formal response. The following FORUM piece represents this response, and draws upon their substantial institutional experience. This piece will likely provide the foundation for a larger, multispecialty response, including American Association of Neurological Surgeons/Congress of Neurological Surgeons, SCAI, and possibly SNIS. Coordination of such an effort remains a work in progress. This piece offers the amalgam of policy and science central to WORLD NEUROSURGERY and provides a timely window to an evolving policy with dramatic implications for the neurosurgery community.

Reporting standards for angioplasty and stent-assisted angioplasty for intracranial atherosclerosis.

BACKGROUND AND PURPOSE: Intracranial cerebral atherosclerosis causes ischemic stroke in a significant number of patients. Technological advances over the past 10 years have enabled endovascular treatment of intracranial atherosclerotic stenosis. The number of patients treated with angioplasty or stent-assisted angioplasty for this condition is increasing. Given the lack of universally accepted definitions, the goal of this document is to provide consensus recommendations for reporting standards, terminology, and written definitions when reporting clinical and radiological evaluation, technique, and outcome of endovascular treatment using angioplasty or stent-assisted angioplasty for stenotic and occlusive intracranial atherosclerosis. SUMMARY OF REPORT: This article was written under the auspices of Joint Writing Group of the Technology Assessment Committee, Society of Neurolnterventional Surgery, Society of Interventional Radiology; Joint Section on Cerebro-vascular Neurosurgery of the American Association of Neurological Surgeons and Congress of Neurological Surgeons; and the Section of Stroke and Interventional Neurology of the American Academy of Neurology. A computerized search of the National Library of Medicine database of literature (PubMed) from January 1997 to December 2007 was conducted with the goal to identify published endovascular cerebrovascular interventional data in stenotic intracranial atherosclerosis that could be used as benchmarks for quality assessment. We sought to identify those risk adjustment variables that affect the likelihood of success and complications. This document offers the rationale for different clinical and technical considerations that may be important during the design of clinical trials for endovascular treatment of intracranial stenotic and occlusive atherosclerosis. Included in this guidance document are suggestions for uniform reporting standards for such trials. These definitions and standards are primarily intended for research purposes; however, they should also be helpful in clinical practice and applicable to all publications. CONCLUSION: In summary, the definitions proposed represent recommendations for constructing useful research data sets. The intent is to facilitate production of scientifically rigorous results capable of reliable comparisons between and among similar studies. In some cases, the definitions contained here are recommended by consensus of a panel of experts in this writing group for consistency in reporting and publication. These definitions should allow different groups to publish results that are directly comparable.

Blood flow imaging: an angle-independent ultrasound modality for intraoperative assessment of flow dynamics in neurovascular surgery.

OBJECTIVE: The objective of this study was to investigate the clinical applicability of navigated blood flow imaging (BFI) in neurovascular applications. BFI is a new 2-dimensional ultrasound modality that offers angle-independent visualization of flow. When integrated with 3-dimensional (3D) navigation technology, BFI can be considered as a first step toward the ideal tool for surgical needs: a real-time, high-resolution, 3D visualization that properly portrays both vessel geometry and flow direction. METHODS: A 3D model of the vascular tree was extracted from preoperative magnetic resonance angiographic data and used as a reference for intraoperative any-plane guided ultrasound acquisitions. A high-end ultrasound scanner was interconnected, and synchronized recordings of BFI and 3D navigation scenes were acquired. The potential of BFI as an intraoperative tool for flow visualization was evaluated in 3 cerebral aneurysms and 3 arteriovenous malformations. RESULTS: The neurovascular flow direction was properly visualized in all cases using BFI. Navigation technology allowed for identification of the vessels of interest, despite the presence of brain shift. The surgeon found BFI to be very intuitive compared with conventional color Doppler methods. BFI allowed for quality control of sufficient flow in all distal arteries during aneurysm surgery and made it easier to discern between feeding arteries and draining veins during surgery for arteriovenous malformations. CONCLUSION: BFI seems to be a promising modality for neurovascular flow visualization that may provide the neurosurgeon with a valuable tool for safer surgical interventions. However, further work is needed to establish the clinical usefulness of the proposed imaging setup.

Bypass surgery for complex brain aneurysms: an assessment of intracranial-intracranial bypass.

OBJECTIVE: Bypass surgery for brain aneurysms is evolving from extracranial-intracranial (EC-IC) to intracranial-intracranial (IC-IC) bypasses that reanastomose parent arteries, revascularize efferent branches with in situ donor arteries or reimplantation, and reconstruct bifurcated anatomy with grafts that are entirely intracranial. We compared results with these newer IC-IC bypasses to conventional EC-IC bypasses. METHODS: During a 10-year period, 82 patients underwent bypass surgery as part of their aneurysm management. A quarter of the patients presented with ruptured aneurysms and two-thirds presented with compressive symptoms from unruptured aneurysms. Most aneurysms (82%) had non-saccular morphology and 56% were giant sized. Common locations included the cavernous internal carotid artery (23%), middle cerebral artery (20%), and posteroinferior cerebellar artery (12%). RESULTS: Forty-seven patients (57%) received EC-IC bypasses and 35 patients (43%) received IC-IC bypasses, including 9 in situ bypasses, 6 reimplantations, 11 reanastomoses, and 9 intracranial grafts. Aneurysm obliteration rates were comparable in EC-IC and IC-IC bypass groups (97.9% and 97.1%, respectively), as were bypass patency rates (94% and 89%, respectively). Three patients died (surgical mortality, 3.7%), and 4 patients were permanently worse as a result of bypass occlusions (neurological morbidity, 4.9%). At late follow-up (mean duration, 41 months), good outcomes (Glasgow Outcome Scale score 5 or 4) were measured in 68 patients (90%) overall, and were similar in EC-IC and IC-IC bypass groups (91% and 89%, respectively). Changes in Glasgow Outcome Scale score were slightly more favorable with IC-IC bypass (6% worse or dead after IC-IC bypass versus 14% with EC-IC bypass). CONCLUSION: IC-IC bypasses compare favorably to EC-IC bypasses in terms of aneurysm obliteration rates, bypass patency rates, and neurological outcomes. IC-IC bypasses can be more technically challenging to perform, but they do not require harvest of extracranial donor arteries, spare patients a neck incision, shorten interposition grafts, are protected inside the cranium, use caliber-matched donor and recipient arteries, and are not associated with ischemic complications during temporary arterial occlusions. IC-IC bypass can replace conventional EC-IC bypass with more anatomic reconstructions for selected aneurysms involving the middle cerebral artery, posteroinferior cerebellar artery, anterior cerebral artery, and basilar apex.

Intraoperative computed tomography with integrated navigation system in a multidisciplinary operating suite.

OBJECTIVE: We report our preliminary experience in a prospective series of patients with regard to feasibility, work flow, and image quality using a multislice computed tomographic (CT) scanner combined with a frameless neuronavigation system (NNS). METHODS: A sliding gantry 40-slice CT scanner was installed in a preexisting operating room. The scanner was connected to a frameless infrared-based NNS. Image data was transferred directly from the scanner into the navigation system. This allowed updating of the NNS during surgery by automated image registration based on the position of the gantry. Intraoperative CT angiography was possible. The patient was positioned on a radiolucent operating table that fits within the bore of the gantry. During image acquisition, the gantry moved over the patient. This table allowed all positions and movements like any normal operating table without compromising the positioning of the patient. For cranial surgery, a carbon-made radiolucent head clamp was fixed to the table. RESULTS: Experience with the first 230 patients confirms the feasibility of intraoperative CT scanning (136 patients with intracranial pathology, 94 patients with spinal lesions). After a specific work flow, interruption of surgery for intraoperative scanning can be limited to 10 to 15 minutes in cranial surgery and to 9 minutes in spinal surgery. Intraoperative imaging changed the course of surgery in 16 of the 230 cases either because control CT scans showed suboptimal screw position (17 of 307 screws, with 9 in 7 patients requiring correction) or that tumor resection was insufficient (9 cases). Intraoperative CT angiography has been performed in 7 cases so far with good image quality to determine residual flow in an aneurysm. Image quality was excellent in spinal and cranial base surgery. CONCLUSION: The system can be installed in a preexisting operating environment without the need for special surgical instruments. It increases the safety of the patient and the surgeon without necessitating a change in the existing surgical protocol and work flow. Imaging and updating of the NNS can be performed at any time during surgery with very limited time and modification of the surgical setup. Multidisciplinary use increases utilization of the system and thus improves the cost-efficiency relationship.

Unruptured intracranial aneurysms and the assessment of rupture risk based on anatomical and morphological factors: sifting through the sands of data.

Aneurysmal subarachnoid hemorrhage continues to have high rates of morbidity and mortality for patients despite optimal medical and surgical management. Due to the fact that aneurysmal rupture can be such a catastrophic event, preventive treatment is desirable for high-risk lesions. Given the variability of the literature evaluating unruptured aneurysms regarding basic patient population, clinical practice, and aneurysm characteristics studied, such as size, location, aspect ratio, relationship to the surrounding vasculature, and the aneurysm hemodynamics, a meta-analysis is nearly impossible to perform. This review will instead focus on the various anatomical and morphological characteristics of aneurysms reported in the literature with an attempt to draw broad inferences and serve to highlight pressing questions for the future in our continued effort to improve clinical management of unruptured intracranial aneurysms.

Target lesion revascularization after wingspan: assessment of safety and durability.

BACKGROUND AND PURPOSE: In-stent restenosis (ISR) occurs in approximately one-third of patients after the percutaneous transluminal angioplasty and stenting of intracranial atherosclerotic lesions with the Wingspan system. We review our experience with target lesion revascularization (TLR) for ISR after Wingspan treatment. METHODS: Clinical and angiographic follow-up results were recorded for all patients from 5 participating institutions in our US Wingspan Registry. ISR was defined as >50% stenosis within or immediately adjacent (within 5 mm) to the implanted stent and >20% absolute luminal loss. RESULTS: To date, 36 patients in the registry have experienced ISR after percutaneous transluminal angioplasty and stenting with Wingspan. Of these patients, 29 (80.6%) have undergone TLR with either angioplasty alone (n=26) or angioplasty with restenting (n=3). Restenting was performed for in-stent dissections that occurred after the initial angioplasty. Of the 29 patients undergoing TLR, 9 required >/=1 interventions for recurrent ISR, for a total of 42 interventions. One major complication, a postprocedural reperfusion hemorrhage, was encountered in the periprocedural period (2.4% per procedure; 3.5% per patient). Angiographic follow-up is available for 22 of 29 patients after TLR. Eleven of 22 (50%) demonstrated recurrent ISR at follow-up angiography. Nine patients have undergone multiple retreatments (2 retreatments, n=6; 3 retreatments, n=2; 4 retreatments, n=1) for recurrent ISR. Nine of 11 recurrent ISR lesions were located within the anterior circulation. The mean age for patients with recurrent anterior circulation ISR was 57.9 years (vs 81 years for posterior circulation ISR). CONCLUSIONS: TLR can be performed for the treatment of intracranial Wingspan ISR with a relatively high degree of safety. However, the TLR results are not durable in approximately 50% of patients, and multiple revascularization procedures may be required in this subgroup.

Assessment of incomplete clipping of aneurysms intraoperatively by a near-infrared indocyanine green-video angiography (Niicg-Va) integrated microscope.

OBJECTIVE: The objective of this article was to assess the clinical use and the completeness of clipping with total occlusion of the aneurysmal lumen, real-time assessment of vascular patency in the parent, branching and perforating vessels, intraoperative assessment of blood flow, image quality, spatial resolution and clinical value in difficult aneurysms using near infrared indocyanine green video angiography integrated on to an operative Pentero neurosurgical microscope (Carl Zeiss, Oberkochen Germany). MATERIALS AND METHODS: Thirteen patients with aneurysms were operated upon. An infrared camera with near infrared technology was adapted on to the OPMI Pentero microscope with a special filter and infrared excitation light to illuminate the operating field which was designed to allow passage of the near infrared light required for excitation of indocyanine green (ICG) which was used as the intravascular marker. The intravascular fluorescence was imaged with a video camera attached to the microscope. ICG fluorescence (700-850 nm) from a modified microscope light source on to the surgical field and passage of ICG fluorescence (780-950 nm) from the surgical field, back into the optical path of the microscope was used to detect the completeness of aneurysmal clipping RESULTS: Incomplete clipping in three patients (1 female and 2 males) with unruptured complicated aneurysms was detected using indocyanine green video angiography. There were no adverse effects after injection of indocyanine green. The completeness of clipping was inadequately detected by Doppler ultrasound miniprobe and rigid endoscopy and was thus complemented by indocyanine green video angiography. CONCLUSION: The operative microscope-integrated ICG video angiography as a new intraoperative method for detecting vascular flow, was found to be quick, reliable, cost-effective and possibly a substitute or adjunct for Doppler ultrasonography or intraoperative DSA, which is presently the gold standard. The simplicity of the method, the speed with which the investigation can be performed, the quality of the images, and the outcome of surgical procedures have all reduced the need for angiography. This technique may be useful during routine aneurysm surgery as an independent form of angiography and/or as an adjunct to intraoperative or postoperative DSA.

Simulation of cerebral hemodynamics for preoperative risk assessment.

BACKGROUND: An important part of the medical treatment of many cerebrovascular diseases is the occlusion of brain supplying arteries. Until now, the risk of this intervention can only be estimated by invasive diagnostics including the risk of cerebrovascular accidents. METHODS AND RESULTS: As a supporting tool, a computer model of the circle of Willis was designed. The model is based upon linear differential equations describing electrotechnical circuits extended non-linearly. By these means, time continuous simulations of different states and the online observation of all calculated state variables such as blood pressure and blood flow in every modeled vessel became feasible. For individual simulations, model parameters were determined by MR-angiography and boundary values by simultaneous Duplex-measurements in both carotid and vertebral arteries. State variables generated by the model behaved physiologically and the reaction of individual cerebrovascular systems in critical situations could be investigated by special scenarios. Inaccuracies concerning the determination of model parameters and boundary values of the used differential equations are likely to be resolved in the near future through a more careful and technically improved determination of these values. CONCLUSIONS: Computer models of subjects were created taking in account the individual anatomical and non-linear physical properties of real vascular systems supplying the brain. Thereby information could be obtained concerning the hemodynamic effects of an iatrogenic vascular occlusion.

Aneurysmal surgery in the presence of angiographic vasospasm: an outcome assessment.

BACKGROUND AND PURPOSE: The timing of aneurysmal surgery for patients presenting within the period at risk for vasospasm (VS) is controversial. The goal of this study is to review our experience of surgically treated patients in the presence of angiographic VS. MATERIALS AND METHODS: From 1990-2004, 894 consecutive patients presented with an aneurysmal subarachnoid hemorrhage (SAH) and were treated with a policy of early surgery. We retrospectively analyzed the patients that had pre-operative angiographic VS. In this study, symptomatic VS was diagnosed when a decreased level of consciousness and/or focal deficit occurred after SAH in the presence of angiographic VS without confounding factors. Functional outcome was assessed three months after SAH using the Glasgow Outcome Scale. RESULTS: Of the 40 patients studied, 62.5% were in good clinical grade Hunt & Hess (H&H 1-2) on admission; 25%, intermediate grade (H&H 3); 12.5%, poor grade (H&H 4-5). Surgery was performed 24 hours or less after initial angiography in 87.5% of patients and less than 48 hours in 97.5%. Pre-operative symptomatic VS was diagnosed in 25%. Post-operatively, angiographic VS was documented in 87.2%. Of the 30% of patients that presented post-operative symptomatic VS, 66.7% also demonstrated pre-operative symptomatic VS. The functional outcome was favorable in 92.5% of the studied patients. Two deaths occurred in patients presenting pre-operative early radiological and symptomatic VS. CONCLUSION: Aneurysmal surgery, especially between 3-12 days following SAH, in the presence of asymptomatic pre-operative angiographic VS can be associated with a good outcome. Early surgery is not contra-indicated and might enable optimal treatment of VS.

Long-term assessment of cerebral perfusion following STA-MCA by-pass in patients.

A prospective study of mean hemispheric cerebral blood flow (CBF) correlated with clinical status has now been completed for the past 54 months. Thirty-eight patients underwent superficial temporal to middle cerebral artery (STA-MCA) by-pass. They were compared with 22 patients with similar arteriographic lesions and clinical symptoms, treated medically throughout the same interval of time. Assignment to either treatment group was not randomized but depended solely on choice of patient or treating physician. Both groups were matched for age, clinical symptoms, angiographic abnormalities, and CBF values. All patients had proximal occlusion of one internal carotid artery or intracranial occlusive disease of the internal carotid or middle cerebral arteries. CBF measurements and clinical evaluations were repeated at regular intervals up to 54 months following surgery or institution of medical treatment. Mean follow up interval after STA-MCA by-pass was 28.7 months and for medical treatment was 29.7 months. Mean hemispheric CBF values for STA-MCA patients became significantly increased 2 weeks after operation. After that, CBF flow values decreased. At 24 months after surgery, flow values for surgically treated patients were significantly higher than among those treated medically, although there were no differences in flow values between the two groups at 3, 6, 12, 36 and 48 months. Prospective clinical evaluations after STA-MCA by-pass were as follows: 12 (32%) improved with cessation of TIAs and/or neurological improvement, 16 (42%) remained unchanged, 7 (18%) deteriorated (due to new or recurrent strokes) and 3 (8%) expired. Clinical results were the same for medical treatment: 6 (27%) improved, 10 (46%) unchanged, 4 (18%) deteriorated due to new or recurrent stroke, and 2 (9%) expired.