Revascularization and aneurysm surgery: current techniques, indications, and outcome

Recurrent and incompletely treated aneurysms

Endovascular treatment of intracranial aneurysms has become an established technique that can provide stable permanent occlusion in over 85 % of the cases. Even those aneurysms considered untreatable by endovascular means can now often be managed by the use of adjunctive measures, e.g., balloon protection devices, intracranial stents, and semipermeable stents, i.e., "flow diverters." In those cases, in which relevant aneurysm recurrences are documented upon angiographic follow-up, both endovascular and surgical techniques can be employed. In rare cases, combined treatment strategies including parent artery occlusion under bypass protection can be performed. At our center, the majority of relevant aneurysm recurrences after initial coil embolization are managed by a second endovascular procedure. In some cases, e.g., aneurysm recurrences not feasible for endovascular re-treatment, documented aneurysmal growth, bleeding from a previously embolized aneurysm, and acute hemorrhagic or ischemic complications during endovascular procedures, surgical management may be necessary. This report briefly outlines the most frequent treatment scenarios.

Bypass and flow reduction for complex basilar and vertebrobasilar junction aneurysms

BACKGROUND

Giant aneurysms of the vertebral and basilar arteries are formidable lesions to treat.

OBJECTIVE

To evaluate the long-term outcomes of patients with vertebrobasilar aneurysms treated with extracranial-intracranial bypass and flow reduction.

METHODS

We retrospectively reviewed a prospective database of aneurysms cases treated between December 1993 and August 2011.

RESULTS

Eleven patients (8 male, 3 female) with 12 aneurysms were treated. There were 3 basilar apex aneurysms, 2 aneurysms of the basilar trunk, and 7 vertebrobasilar junction aneurysms. There were 5 saccular and 7 fusiform aneurysms. All patients underwent extracranial-intracranial bypass and vessel occlusion. Flow was reversed or reduced by complete (n = 6) or partial occlusion of the basilar artery (n = 3) or by occlusion of the vertebral arteries distal to the posterior inferior cerebellar artery (n = 3). Postoperatively (mean follow-up, 71.6 months; range, 4-228; median, 49 months), the bypass patency rate was 92.3% (12/13). The perioperative mortality rate for the initial treatment was 18.2% (2/11). In 4 cases, the aneurysms continued to grow and required further treatment; after re-treatment, 3 of these patients died. Of the initial 11 patients, 6 were treated successfully and 5 died. The mean preoperative modified Rankin Scale score was 2.1 (range, 1-3; median, 2). At last follow-up for all patients, the mean modified Rankin Scale score was 3.45 (range, 1-6; median, 3) and 2.5 (range, 1-4; median, 2.5) for the 6 long-term survivors.

CONCLUSION

Vertebrobasilar aneurysms are challenging lesions with limited microsurgical or endovascular options. Despite aggressive surgical treatment, the long-term outcome remains poor for most patients.

Monitoring Flow in Extracranial-Intracranial Bypass Grafts Using Duplex Ultrasonography: A Single-Center Experience in 80 Grafts Over 8 Years

BACKGROUND:

High-flow extracranial-intracranial (EC-IC) bypass is performed by using radial artery graphs (RAGs) or saphenous vein grafts (SVGs) for various pathologies such as aneurysms, ischemia, and skull-base tumors. Quantifying the acceptable amount of blood flow to maintain proper cerebral perfusion has not been well established, nor have the variables that influence flow been determined.

OBJECTIVE:

To identify the normative range of blood flow through extracranial-intracranial RAGs and SVGs as measured by duplex ultrasonography. Multiple variables were evaluated to better understand their influence of graft flow.

METHODS:

All EC-IC grafts performed at Harborview Medical Center from 2005 to 2012 were retrospectively reviewed for this cohort study. Daily extracranial graft duplex ultrasonography with flow volumes and transcranial graft Doppler were examined, as were short- and long-term outcomes. Both ischemic and hyperemic events were evaluated in further detail.

RESULTS:

Eighty monitorable high-flow EC-IC bypasses were performed over the 8-year period. Sixty-five bypasses were performed by using RAGs and 15 were performed with SVGs. The average flow was 133 mL/min for RAGs and 160 mL/min for SVGs (P = .25). For both RAG and SVG groups, the donor and recipient vessel selected significantly impacted flow. For the RAG group only, preoperative graft diameter, postoperative hematocrit, and postoperative date significantly influenced flow. A 1-week average of >200 mL/min was 100% sensitive to cerebral hyperemia syndrome.

CONCLUSION:

This study establishes the normative range of duplex ultrasonographic flow after high-flow EC-IC bypass, as well the usefulness and practicality of such monitoring as a surrogate to flow in the postoperative period.

Surgical simulation of cerebral revascularization via skull base approaches in the posterior circulation using three-dimensional skull model with artificial brain and blood vessels

Posterior circulation revascularization is a challenging technique because microanastomosis must be performed in deep locations. A reproducible simulation model is proposed for training. The prototype three-dimensional skull model with artificial brain was used. The mesencephalic segment of superior cerebellar artery (SCA) and the caudal loop of the posterior inferior cerebellar artery (PICA) were made from artificial blood vessels and glued on the brain. The skull model was drilled to perform the presigmoid transpetrosal approach and then superficial temporal artery-SCA anastomosis was performed under the operating microscope. The skull model was also drilled to perform the far lateral approach and then occipital artery-PICA anastomosis was performed. The skull model with artificial brain and arteries allows simulation and training in the surgical techniques of posterior circulation revascularization with skull base approaches.

3D computational fluid dynamics of a treated vertebrobasilar giant aneurysm: a multistage analysis

BACKGROUND AND PURPOSE

The treatment of giant aneurysms of the vertebrobasilar junction remains a challenging task in neurosurgical practice, and the reference standard therapy is still under debate. Through a detailed postmortem study, we analyzed the hemodynamic factors underlying the formation and recanalization of an aneurysm located at this particular site and its anatomic configuration.

METHODS

An adult fixed cadaveric specimen with a known VBJ GA, characterized radiographically and treated with endovascular embolization, was studied. 3D computational fluid dynamic models were built based on the specific angioarchitecture of the specimen, and each step of the endovascular treatment was simulated.

RESULTS

The 3D CFD study showed an area of hemodynamic stress (high wall shear stress, high static pressure, high flow velocity) at the neck region of the aneurysm, matching the site of recanalization seen during the treatment period.

CONCLUSIONS

Aneurysm morphologic features, location, and patient-specific angioarchitecture are the principal factors to be considered in the management of VBJ giant aneurysms. The 3D CFD study has suggested that, in the treatment of giant aneurysms, the intra-aneurysmal environment induced by partial coil or Onyx embolization may lead to hemodynamic stress at the neck region, potentially favoring recanalization of the aneurysm.

Selective-targeted extra-intracranial bypass surgery in complex middle cerebral artery aneurysms: correctly identifying the recipient artery using indocyanine green videoangiography

BACKGROUND

Treatment of complex middle cerebral artery (MCA) aneurysms often requires vessel sacrifice or prolonged temporary occlusion with extra- to intracranial (EC-IC) bypass to preserve perfusion. A crucial surgical step is the identification of the bypass recipient artery matching the distal territory of the involved vessel.

OBJECTIVE

To report about the feasibility and efficiency of an indocyanine green videoangiography (ICG-VA) assisted technique for identification of cortical recipient vessels to perform selective-targeted EC-IC bypass.

METHODS

The proposed technique is based on the analysis of differences in the timing of filling of M4 vessels seen on serial ICG-VAs. A delayed fluorescence can be visualized either primarily on a baseline ICG-VA or secondarily on an ICG-VA performed during temporary occlusion of the involved MCA branch. M4 branches presenting delayed fluorescence represent suitable bypass recipient arteries. We report 7 consecutive patients treated for complex MCA aneurysms with selective-targeted EC-IC bypass.

RESULTS

Application of the proposed technique permitted the correct identification of recipient arteries (cortical branches of the involved MCA segment) in all patients. The cortex distal to the occlusion filled concomitantly on ICG-VA at the end of surgery. All patients underwent successful treatment of the aneurysm, including a cortical bypass. There were no ischemic complications, and a favorable clinical outcome was achieved in all patients (modified Rankin Scale at follow-up ≤ modified Rankin Scale preoperative).

CONCLUSION

The proposed ICG-VA-based technique enables reliable and accurate identification of the cortical recipient artery and eliminates the risk of erroneous revascularization of noninvolved territories.

Intraoperative neurophysiological monitoring of extracranial-intracranial bypass procedures

OBJECT

Intraoperative neurophysiological monitoring (IONM) represents an established tool in neurosurgery to increase patient safety. Its application, however, is controversial. Its use has been described as helpful in avoiding neurological deterioration during intracranial aneurysm surgery. Its impact on extracranial-intracranial (EC-IC) bypass surgery involving parent artery occlusion for the treatment of complex aneurysms has not yet been studied. The authors therefore sought to evaluate the effects of IONM on patient safety, the surgeon's intraoperative strategies, and functional outcome of patients after cerebral bypass surgery. Intraoperative neurophysiological monitoring results were compared with those of intraoperative blood flow monitoring to assess bypass graft perfusion.

METHODS

Compound motor action potentials (CMAPs) were generated using transcranial electrical stimulation in patients undergoing EC-IC bypass surgery. Preoperative and postoperative motor function was analyzed. To assess graft function, intraoperative flowmetry and indocyanine green fluorescence angiography were performed. Special care was taken to compare the relevance of electrophysiological and blood flow monitoring in the detection of critical intraoperative ischemic episodes.

RESULTS

The study included 31 patients with 31 aneurysms and 1 bilateral occlusion of the internal carotid arteries, undergoing 32 EC-IC bypass surgeries in which radial artery or saphenous vein grafts were used. In 11 cases, 15 CMAP events were observed, helping the surgeon to determine the source of deterioration and to react to it: 14 were reversible and only 1 showed no recovery. In all cases, blood flow monitoring showed good perfusion of the bypass grafts. There were no false-negative results in this series. New postoperative motor deficits were transient in 1 case, permanent in 1 case, and not present in all other cases.

CONCLUSIONS

Intraoperative neurophysiological monitoring is a helpful tool for continuous functional monitoring of patients undergoing large-caliber vessel EC-IC bypass surgery. The authors' results suggest that continuous neurophysiological monitoring during EC-IC bypass surgery has relevant advantages over flow-oriented monitoring techniques such as intraoperative flowmetry or indocyanine green-based angiography.

Pediatric bypasses for aneurysms and skull base tumors: short- and long-term outcomes

OBJECT

Cerebral bypass is a useful microsurgical technique for the treatment of unclippable aneurysms and invasive skull base tumors. The authors present the largest reported series of cerebrovascular bypasses in the pediatric population. They describe the short- and long-term clinical and radiographic outcomes of extracranial-intracranial and local bypasses performed for complex cerebral aneurysms and recurrent, invasive, and malignant skull base tumors in pediatric patients.

METHODS

A consecutive series of 17 pediatric patients who underwent revascularization were analyzed retrospectively for indications, graft patency, and neurological outcomes.

RESULTS

The mean age was 12 years (median 11 years, range 4-17 years), and there were 7 boys (41%) and 10 girls (59%). A total of 18 bypasses were performed in 17 patients and included 10 aneurysm cases (55.5%) and 8 tumor cases (45%). Of these 18 bypasses, there were 11 (61.1%) extracranial-intracranial bypasses (10 saphenous vein grafts [90%] and 1 radial artery graft [10%]), 1 side-to-side anastomosis (5.5%), 2 intracranial reimplants (11.1%), and 4 interposition bypass grafts (22.2%; 2 radial artery grafts, 1 saphenous vein graft, and 1 lingual artery graft). The mean clinical follow-up was 40.5 months (median 24 months, range 3-197 months). The mean radiographic follow-up was 40 months (median 15 months, range 9-197 months). Eighty-two percent of patients (14 of 17) achieved a modified Rankin Scale score between 0 and 2; however, 2 patients died of disease progression during long-term follow-up. The short-term (0- to 3-month) graft patency rate was 100%. Two patients had graft stenosis (11.7%) and underwent graft revisions. Two patients (11.1%) with giant middle cerebral artery aneurysms (> 25 mm) had strokes postoperatively but recovered without a persistent neurological deficit. One patient observed for 197 months showed a stable dysplastic change at the end of the graft. The long-term graft patency was 100% with a mean follow-up of 40 months. There were 2 deaths in the cohort during follow-up; both patients died of malignant tumors (osteogenic sarcoma and chondrosarcoma).

CONCLUSIONS

The authors conclude that in properly selected cases, bypasses can be safely performed in patients with aneurysms and skull base tumors. The bypasses remained patent over long periods of time despite the growth of the patients.

Universal extracranial-intracranial graft bypass for large or giant internal carotid aneurysms: techniques and results in 38 consecutive patients

OBJECTIVE

To present indications, surgical techniques, and outcomes of extracranial-intracranial (EC-IC) graft bypass.

METHODS

Between January 1996 and June 2011, 38 patients with large or giant internal carotid artery (ICA) aneurysms were treated using graft bypass, employing the radial artery (RA) or the saphenous vein (SV) as a graft. Preoperative balloon test occlusions were not performed in any of the cases. In 17 patients, the external carotid artery (ECA)-RA-M2 segment of the middle cerebral artery bypass was used for treatment, and ECA-SV-M2 bypass was used in 21 patients.

RESULTS

All aneurysms were completely trapped, and there were no subarachnoid hemorrhages or recanalizations of aneurysms during the follow-up period (8-170 months). Of the 38 bypasses, 36 (94.7%) remained patent, and there were no permanent neurologic deficits. Hyperperfusion syndrome was not experienced in this series. There were 2 temporary neurologic deficits. In 1 case using the RA, graft vasospasm occurred, and kinking occurred in 1 case using the SV. Another patient with a SV graft had to undergo an emergent revision of the graft 8 hours after the initial operation. One patient with a SV graft underwent a second operation to control an epidural abscess.

CONCLUSIONS

Universal EC-IC graft bypass is a safe and effective method for treating large or giant ICA aneurysms.

Surgical management of giant posterior communicating artery aneurysms

BACKGROUND

Giant posterior communicating artery (PCoA) aneurysms (> 25 mm) are rare lesions associated with a poor prognosis and high rates of morbidity and mortality.

OBJECTIVE

To review the clinical results of giant PCoA aneurysms surgically treated at our institution, focusing on operative nuances.

METHODS

All cases of giant PCoA aneurysms treated surgically at our institution were identified from a prospectively maintained patient database. Patient demographic factors, medical comorbidities, rupture status, neurological presentation, clinical outcomes, and surgical records were critically reviewed.

RESULTS

From 1989 to 2010, 11 patients (10 women) underwent surgical clipping of giant PCoA aneurysms. Presenting signs and symptoms included cranial nerve palsies, diminished mental status, headache, visual changes, and seizures. Five aneurysms were ruptured on admission. All aneurysms were clipped primarily except 1, which was treated by parent artery sacrifice and extracranial-to-intracranial bypass after intraoperative aneurysm rupture. Perioperative morbidity and mortality rates were 36% (4 of 11) and 18.3% (2 of 11), respectively. Excellent or good clinical outcomes, defined as modified Rankin Scale scores ≤ 2, were achieved in 86% (5 of 6) of patients available for long-term clinical follow-up (mean, 12.5 ± 13.6 months).

CONCLUSION

Giant PCoA aneurysms are rare vascular lesions that may present with a variety of neurological signs and symptoms. These lesions can be successfully managed surgically with satisfactory morbidity and mortality rates. To the best of our knowledge, this is the largest surgical series of giant PCoA aneurysms published to date.

Extracranial-Intracranial Bypass and Vessel Occlusion for the Treatment of Unclippable Giant Middle Cerebral Artery Aneurysms

BACKGROUND:

Giant middle cerebral artery (MCA) aneurysms pose management challenges.

OBJECTIVE:

To review the outcomes of patients with giant MCA aneurysms not amenable to clipping or vessel reconstruction treated with extracranial-intracranial (EC-IC) bypass and vessel sacrifice.

METHODS:

We retrospectively reviewed a database of aneurysms treated at our institution between 1983 and 2011.

RESULTS:

Sixteen patients (11 males, 5 females) were identified. There were 10 saccular, 4 fusiform, and 2 serpentine aneurysms. The aneurysms predominantly involved the M1 segment in 5 cases, M2 in 9 cases, and both M1 and M2 in 2 cases. The EC-IC bypasses performed included 13 superficial temporal artery-MCA, 1 saphenous vein graft-MCA, and 2 radial artery grafts-MCA. The postoperative bypass patency rate was 93.8% (15/16). There were 3 cerebrovascular accidents (18.8%), but no perioperative deaths (0% mortality). The mean follow-up was 58.4 months (range, 1-265; median, 23.5 months). In 75% (12/16) of cases the aneurysms were occluded successfully. A small residual was noted in 3 cases with the use of this treatment strategy, and they were re-treated. In a fourth case treated with partial distal occlusion, reduced flow through the aneurysm was noted postoperatively, but the patient did not undergo further treatment. The mean modified Rankin scale and mean Glasgow Outcome Scale scores at last follow-up were 1.6 (range, 1-4; median, 1) and 4.8 (range, 3-5; median, 5), respectively.

CONCLUSION:

Giant MCA aneurysms are challenging lesions. EC-IC bypass with parent vessel occlusion can provide a durable form of treatment with acceptable rates of morbidity and mortality.

Direct, High-flow Bypass for a Pediatric Giant, Fusiform Aneurysm of the Inferior Division of M2: Case Report and Review of Literature

In this case report, we describe the first reported case of treating a 7-year-old male patient who has a giant, fusiform aneurysm confined to the inferior M2 segment by means of a saphenous vein graft. Given the lack of good endovascular management options for this particular scenario, craniotomy was recommended and an end-to-side ECA-ICA anastomosis was carried out with technical details of the surgery outlined in the manuscript. The patient did not sustain any major postoperative complications. The graft remained patent upon completion of the surgery and at the time of last follow-up, 9 months post-surgery. This case serves as an illustrative example of the need for high-flow bypass for a select few patients even as endovascular technology continues to improve.

Stent-assisted coil trapping in a manual internal carotid artery compression test for the treatment of a fusiform dissecting aneurysm

Internal carotid artery (ICA) trapping can be used for the treatment of giant intracranial aneurysms, blood blister-like aneurysms, and fusiform dissecting aneurysms. Fusiform dissecting aneurysms are challenging to treat surgically and endovascularly because of no definite neck and critical perforators. Surgical or endovascular trapping of the ICA with or without an extracranial-intracranial bypass has commonly been used as an effective method to treat these lesions, but balloon test occlusion (BTO) must be performed. Here, we report a case of a ruptured fusiform dissecting aneurysm of the distal ICA, which was successfully treated using an endovascular ICA trapping with a manual ICA compression test instead of BTO.

Surgical strategies for aneurysms deemed unclippable and uncoilable

Although most cerebral aneurysms can nowadays be successfully treated either by standard clipping or sole coiling, a subset of aneurysms may not be amenable to standard clipping or coiling and require alternative treatment options. Surgical options, other than clipping and/or endovascular options other than sole coiling, may be the optimal treatment plan for some complex aneurysms. Surgical strategies for such complex aneurysms include parent artery occlusion, revascularization procedures and flow redirection. In this article, we review which factors are predictive of failure of conventional aneurysm treatment options; summarize key information needed to orient treatment decision; and discuss surgical options for unclippable and uncoilable aneurysms.

Petrous carotid exposure with eustachian tube preservation: a morphometric elucidation

Inadvertent injury to eustachian tube leading to cerebrospinal fluid rhinorrhea is a known complication associated with drilling of Glasscock's triangle to expose the horizontal petrous internal carotid artery (ICA) for management of difficult tumors (especially malignant) or aneurysms at the cranial base. Contrary to the usual approach, we hypothesize that a "medial-to-lateral" approach to Glasscock's triangle drilling will minimize eustachian tube injury. Four formalin-fixed human cadaveric heads were dissected, and underwent appropriate morphometric analysis; yielding a total of eight datasets. The diameter of the horizontal petrous ICA exposed was 4.7 ± 0.9 mm (range, 3.8 to 5.6 mm).The mean distance from the medial carotid wall midpoint to the medial-most point on the eustachian tube was 6.35 ± 0.58 mm (range, 5.4 to 7.1 mm), yielding a "safety zone" for eustachian tube, ranging 0.2 to 1.9 mm lateral to the lateral carotid wall. With the medial-to-lateral approach, the eustachian tube remained preserved in all the specimens. The results of our study provide a practical, consistent, and safe method of maximizing horizontal petrous carotid artery exposure while minimizing the eustachian tube injury.

Revascularization for complex cerebral aneurysms

BACKGROUND AND PURPOSE

Complex cerebral aneurysms may require indirect treatment with revascularization. This manuscript describes various surgical revascularization techniques together with clinical outcomes.

METHODS

Thirty-two consecutive patients with complex cerebral aneurysm were managed from November 2005 to October 2008. Techniques used for revascularization were high-flow bypass, low-flow bypass, branch artery reimplantion, and primary reanastomosis. Physiologic and anatomic monitoring technologies, including electroencephalography, somatosensory evoked potential monitoring, microvascular doppler ultrasonography, and/or indocyanine green videoangiography were used intraoperatively to assess both brain physiology and vascular anatomy. Patient outcome was determined using the Glasgow Outcome Scale at discharge and at a mean of 12 months post operation (range 6-25 months).

RESULTS

Two cervical carotid aneurysms (6%) were resected followed by primary reanastomosis, 21 aneurysms (66%) were trapped following saphenous vein high-flow bypasses, five (16%) were clipped after superficial temporal or occipital artery low-flow bypasses, and four (12%) middle cerebral branch arteries were reimplanted. Of the 32 patients at discharge, 29 (91%) had a Glasgow Outcome Scale of four or five, two (6%) had severe disability, and one (3%) died.

CONCLUSION

Cerebral revascularization remains an effective and reliable procedure for treatment of complex cerebral aneurysms. Low morbidity and mortality rates reflect the maturity of patient selection and surgical technique in the management of these lesions.

Endovascular Treatment of Basilar Trunk Saccular Aneurysms

Basilar artery (BA) trunk aneurysms are rare and still remain a formidable surgical challenge. The purpose of this retrospective study was to report the clinical entities and results of endovascular surgery of BA trunk saccular aneurysms. Between 1995 and 2009, 14 patients with 14 BA trunk saccular aneurysms underwent endovascular surgery. Six patients presented subarachnoid hemorrhage (SAH), three patients had another associated aneurysm which developed SAH, one patient presented with mass effect to the brain stem, and four patients were incidentally discovered. Five ruptured and seven unruptured aneurysms were successfully treated by endovascular surgery. Another one incompletely embolized aneurysm had grown to huge size five years later and the patient underwent a Hunterian ligation with a radial artery graft between the extracranial vertebral artery and the posterior cerebral artery. In one ruptured case, we attempted neck clipping, but this was abandoned because of concern for neck tearing by clipping. The aneurysm was embolized using detachable coils later. BA trunk aneurysms showed characteristic features such as so-called lateral aneurysm (43%), multiple aneurysms (43%) and four BA fenestrations (36%). The unusual high incidence of associated various vascular anomalies suggests that focal wall weakness must be based on the mechanism of aneurysm initiation on the BA trunk. Most patients presented with SAH. Pre-treatment neurological state was predictive for clinical outcome. Endovascular surgery is an effective therapeutic alternative that is associated with low morbidity and mortality rates, and should be considered the first choice treatment.

Extracranial-intracranial bypass surgery using a radial artery interposition graft for cerebrovascular diseases

OBJECTIVE

To investigate the efficacy of extracranial-intracranial (EC-IC) bypass surgery using a radial artery interposition graft (RAIG) for surgical management of cerebrovascular diseases.

METHODS

The study involved a retrospective analysis of 13 patients who underwent EC-IC bypass surgery using RAIG at a single neurosurgical institute between 2003 and 2009. The diseases comprised intracranial aneurysm (n=10), carotid artery occlusive disease (n=2), and delayed stenosis in the donor superficial temporal artery (STA) following previous STA-middle cerebral artery bypass surgery (n=1). Patients were followed clinically and radiographically.

RESULTS

Bypass surgery was successful in all patients. At a mean follow-up of 53.4 months, the short-term patency rate was 100%, and the long-term rate was 92.3%. Twelve patients had an excellent clinical outcome of Glasgow Outcome Scale (GOS) 5, and one case had GOS 3. Procedure-related complications were a temporary dysthesia on the graft harvest hand (n=1) and a hematoma at the graft harvest site (n=1), and these were treated successfully with no permanent sequelae. In one case, spasm occurred which was relieved with the introduction of mechanical dilators.

CONCLUSION

EC-IC bypass using a RAIG appears to be an effective treatment for a variety of cerebrovascular diseases requiring proximal occlusion or trapping of the parent artery.

Management of Residual and Recurrent Aneurysms After Initial Endovascular Treatment

Background:

Coil instability possibly translating into higher delayed rebleeding rates remains a concern in the endovascular management of cerebral aneurysms.

Objective:

To report on 127 patients with endovascular aneurysmal remnants who underwent re-treatment over an 18 year period.

Methods:

Patients presenting with aneurysm residuals >20% of the original lesion, unstable neck remnants, aneurysmal regrowth, or new aneurysmal daughter sacs were treated by an individualized approach, using both endovascular and surgical techniques.

Results:

Seventy-five aneurysmal remnants (59.1%) were treated by further re-embolization. Standard coil embolization was used in 65 cases, stent-protected coiling in 9 cases, and balloon remodeled coiling in 1 case, respectively. Fifty-two (40.9%) aneurysmal remnants were treated surgically. Standard microsurgical clipping was used in 44 patients, parent artery occlusion or trapping under bypass protection in 5 cases, deliberate clipping of the basilar artery trunk in 2 cases, and aneurysm wrapping in one case, respectively. Mechanisms of aneurysm recurrence were coil compaction in 93 cases and regrowth in 34 cases. A single reembolization was sufficient to occlude 78.7% of recurrences from coil compaction, but only 14.3% of recurrences from aneurysm regrowth.

Conclusion:

The individualized approach resulted in complete occlusion of 114 aneurysms (89.7%), with neck remnants and residual aneurysms detectable in 11 (8.7%) and 2 (1.6%) cases, respectively. Treatment morbidity was 11.9%, without significant differences between surgical (15.6%) and endovascular (9.3%) patients (P = .09). Recurrences from coil compaction were safely treated by re-embolization, whereas recurrences from aneurysmal regrowth may best be managed surgically when technically feasible.

Internal carotid artery sacrifice for radical resection of skull base tumors

When dealing with skull base tumors that encase the internal carotid artery (ICA), the surgeon must decide between ICA preservation and incomplete tumor resection, or radical resection with ICA sacrifice. In our experience with more than 300 anterior skull base tumors, the ICA was sacrificed in only 10 patients. These tumors were malignant, except for one meningioma that occluded the ICA and produced translent ischemic symptoms. All patients had the ICA resected with the tumor, and all patients underwent revascularization (cervical ICA-MCA saphenous bypass, n = 4; cervical-to-supraclinoid bypass, n = 1; petrous-to-supraclinoid bypass, n = 3; bonnet bypass, n = 2). This small patient series reflects our practice of preserving the ICA whenever possible. We recommend preserving the ICA with benign tumors because they do not invade the artery, or do so only to a limited extent. In addition, similar rates of tumor recurrence are seen after aggressive resection with or without ICA sacrifice. In contrast, we recommend radical tumor resection and sacrifice of the ICA with malignant tumors because they directly threaten the integrity of the ICA and the patient's survival. The ICA should not be considered a limitation to radical tumor resection because the ICA can be reconstructed safely with an appropriate bypass procedure.

Intracranial aneurysms in adolescents

PURPOSE

Intracranial aneurysms are extremely uncommon in adolescents. This study was undertaken to assess the clinical and radiological characteristics and clarify the choice of therapeutic strategies of intracranial aneurysms in adolescents with age range from 15 to 18 years.

METHODS

From our dedicated aneurysmal databank between October 1985 and July 2008, we reviewed 16 consecutive adolescents who had 20 intracranial aneurysms.

RESULTS

Ten boys and six girls (male/female ratio = 1.67:1; mean age 16.78 ± 1.18 years) were included in the present study. Intracranial aneurysms in adolescents constituted 0.91% of all intracranial aneurysms. It was found that 25% of the lesions were in the posterior circulation, while 75% of the lesions were in the anterior circulation, and 25% developed on the middle cerebral artery (MCA). Half of the patients presented with subarachnoid hemorrhage and others mainly presented with mass effect such as weakness in the extremities, diplopia, and dysfunction of eye movement. Eight cases underwent endovascular treatment: including GDC therapy in five patients, parental artery occlusion in two patients, and cover stent implantation in one patient with pseudoaneurysm of the cavernous segment of the left internal carotid artery. Four patients received microsurgical therapy: aneurismal neck clipping for two patients and extracranial-intracranial (EC-IC) bypass and trapping of complex aneurysms in MCA for the other two patients. Four patients did not receive microsurgical or endovascular therapy, including a boy whose aneurysm spontaneously thrombosed preoperatively and a girl who died before operation because of rerupture of aneurysm. Two patients did not undergo therapy owing to the high operative risk. All of the patients who received therapy had favorable outcome (GOS 4 or 5) at discharge and at follow-up.

CONCLUSIONS

Intracranial aneurysms in adolescents differ from those in adults in many ways including the following: male predominance; high incidence of large or giant, traumatic, dissecting, and fusiform aneurysms; high incidence of aneurysms in the posterior circulation; high incidence of spontaneous thrombosis; better Hunt-Hess grade at presentation; and better therapeutic outcome. Both microsurgical approaches and endovascular treatment were effective. For some giant, complex intracranial aneurysms, parent artery occlusion or EC-IC bypass is the best treatment choice.

Carotid artery sacrifice for unclippable and uncoilable aneurysms: endovascular occlusion vs common carotid artery ligation

BACKGROUND

Optimal treatment of intracranial aneurysms involves complete occlusion of the aneurysm with preservation of the parent artery and all of its branches. Attempts to occlude the aneurysm and preserve the parent artery may be associated with a higher level of risk than parent vessel occlusion or trapping.

OBJECTIVE

To evaluate our series of patients with large and giant aneurysms who underwent treatment via endovascular coiling with parent artery sacrifice or surgical ligation of the common carotid artery (CCA) and gain insight into the advantages and risks of each of these alternatives.

METHODS

We retrospectively reviewed all patients with aneurysms who underwent carotid sacrifice via endovascular occlusion or surgical CCA ligation during an 8-year period at our institution.

RESULTS

Twenty-seven patients with large and giant aneurysms of the internal carotid artery underwent carotid artery sacrifice via endovascular occlusion (n = 15) or CCA ligation (n = 12). Of the patients who underwent endovascular occlusion, 3 developed groin complications, 1 developed a new sixth nerve palsy, 1 died from vasospasm related to subarachnoid hemorrhage, and 1 died secondary to rupture of an associated 3-mm anterior communicating artery aneurysm 5 days postoperatively. Of the patients undergoing CCA ligation, 1 patient developed a partial hypoglossal palsy. Clinical improvement of presenting symptoms was observed in all surviving patients regardless of the method of treatment. Complete aneurysm obliteration was documented in all patients during the initial hospital stay. The mean radiographic long-term follow-up was 14.2 months, which was available in 20 of the 25 surviving patients (80%). Complete obliteration was confirmed at follow-up in all but 2 patients with large cavernous aneurysms; 1 was initially treated with endovascular occlusion and the other with carotid ligation.

CONCLUSION

Parent artery sacrifice is still a viable treatment for some complex aneurysms of the internal carotid artery. CCA ligation is a reasonable alternative to endovascular arterial sacrifice.

Endovascular stenting of an extracranial-intracranial saphenous vein high-flow bypass graft: Technical case report

Background:

The authors describe a case of endovascular stenting of an extracranial–intracranial saphenous vein high-flow bypass graft in the management of a complex bilateral carotid aneurysm case.

Case Description:

A 43-year-old woman was admitted with progressive visual field restriction and headache. Imaging studies revealed bilateral supraclinoid carotid aneurysms. The right carotid aneurysm was clipped and the left one was treated by an endovascular procedure, after performing an internal carotid artery–middle cerebral artery (ICA-MCA) saphenous vein bypass graft. A few months following the bypass procedure, a 70–80% stenosis of the graft was discovered and treated endovascularly with a stenting procedure. Follow-up at 36 months after the first operation showed the patency of the venous graft and no neurological deficits.

Conclusions:

Endovascular stenting of the extracranial–intracranial saphenous vein high-flow bypass graft is technically feasible when postoperative graft occlusion is discovered.

The azygos anterior cerebral artery bypass: double reimplantation technique for giant anterior communicating artery aneurysms

The authors introduce the azygos anterior cerebral artery (ACA) bypass as an option for revascularizing distal ACA territories, as part of a strategy to trap giant anterior communicating artery (ACoA) aneurysms. In this procedure, the aneurysm is exposed with an orbitozygomatic-pterional craniotomy and distal ACA vessels are exposed with a bifrontal craniotomy. The uninvolved contralateral A2 segment of the ACA serves as a donor vessel for a short radial artery graft. The contralateral pericallosal artery (PcaA) and the callosomarginal artery (CmaA) are connected to the graft in the interhemispheric fissure using the double reimplantation technique. Three anastomoses create an azygos system supplying the entire ACA territory, enabling the surgeon to trap the aneurysm incompletely. Retrograde flow from the CmaA supplies the ipsilateral recurrent artery of Heubner, and the aneurysm lumen thromboses.

The azygos bypass was successfully performed to treat a 47-year-old woman with a giant, thrombotic ACoA aneurysm supplied by the A1 segment of the left ACA, with left PcaA and CmaA originating from the aneurysm base.

The authors conclude that the azygos ACA bypass is a novel option for revascularizing PcaA and CmaA, as part of the overall treatment of giant ACoA aneurysms.

Predictors of Clinical and Angiographic Outcome After Surgical or Endovascular Therapy of Very Large and Giant Intracranial Aneurysms

BACKGROUND:

Risk factors for poor outcome in the treatment of very large (≥20-24 mm) and giant (≥25 mm) intracranial aneurysms remain incompletely defined.

OBJECTIVE:

To present an aggregate clinical series detailing a 24-year experience with very large and giant aneurysms to identify and assess the relative importance of various patient, aneurysm, and treatment-specific characteristics associated with clinical and angiographic outcomes.

METHODS:

The authors retrospectively identified 184 aneurysms measuring 20 mm or larger (85 very large, 99 giant) treated at Stanford University Medical Center between 1984 and 2008. Clinical data including age, presentation, and modified Rankin Scale (mRS) score were recorded, along with aneurysm size, location, and morphology. Type of treatment was noted and clinical outcome measured using the mRS score at final follow-up. Angiographic outcomes were completely occluded, occluded with residual neck, partly obliterated, or patent with modified flow.

RESULTS:

After multivariate analysis, risk factors for poor clinical outcome included a baseline mRS score of 2 or higher (odds ratio [OR], 0.23; 95% confidence interval [CI]: 0.08-0.66; P = .01), aneurysm size of 25 mm or larger (OR, 3.32; 95% CI: 1.51-7.28; P < .01), and posterior circulation location (OR, 0.18; 95% CI: 0.07-0.43; P < .01). Risk factors for incomplete angiographic obliteration included fusiform morphology (OR, 0.25; 95% CI: 0.10-0.66; P #x003C; .01), posterior circulation location (OR, 0.33; 95% CI: 0.13-0.83; P = .02), and endovascular treatment (OR, 0.14; 95% CI: 0.06-0.32; P < .01). Patients with incompletely occluded aneurysms experienced higher rates of posttreatment subarachnoid hemorrhage and had increased mortality compared with those with completely obliterated aneurysms.

CONCLUSION:

Our results suggest that patients with poor baseline functional status, giant aneurysms, and aneurysms in the posterior circulation had a significantly higher proportion of poor outcomes at final follow-up. Fusiform morphology, posterior circulation location, and endovascular treatment were risk factors for incompletely obliterated aneurysms.

Short Segment Internal Maxillary Artery to Middle Cerebral Artery Bypass: A Novel Technique for Extracranial-to-Intracranial Bypass

BACKGROUND:

Traditional high-flow extracranial-to-intracranial (EC-IC) bypass procedures require a cervical incision and a long (20–25 cm) radial artery or saphenous vein graft. This technical note describes a less invasive, EC-IC bypass technique using a short-segment (8–10 cm) of the radial artery to anastomose the internal maxillary artery (IMAX) to the middle cerebral artery.

CLINICAL PRESENTATION:

Anatomic dissections were performed on 6 cadaveric specimens to assess the location of the IMAX artery using an extradural middle fossa approach. Subsequently, the procedure was implemented in a patient with a giant fusiform internal carotid artery aneurysm.

TECHNIQUE:

A straight line was drawn anteriorly from the V2/V3 apex along the inferior edge of V2. The IMAX was found 8.6 mm on average anteriorly from the lateral edge of the foramen rotundum. We drilled to a depth of 4.2 mm on average to find the medial extent of the artery and then lateral and deep drilling exposed an average of 7.8 mm of graft. The IMAX was consistently found running just anterior and parallel to a line between the foramens rotundum and ovale. In the clinical case presented, both intraoperative indocyanine green and postoperative conventional angiography revealed a patent graft. The patient did well clinically without any new deficits.

CONCLUSION:

The advantages of this new technique include the avoidance of a long cervical incision and potentially higher patency rates secondary to shorter graft length than currently practiced.

Vertebral artery dissecting aneurysm treated by proximal occlusion and posterior inferior cerebellar artery reconstruction with fenestrated clips. Case report

A 57-year-old man presented with subarachnoid hemorrhage caused by a dissecting aneurysm of the vertebral artery close to the origin of the posterior inferior cerebellar artery (PICA). The aneurysm was treated successfully with two fenestrated clips preserving the efferent artery with anterograde blood flow without PICA anastomosis. The postoperative course was uneventful. Postoperative angiography indicated disappearance of the aneurysm and anterograde blood flow of the PICA.

Intracranial in situ side-to-side microvascular anastomosis: principles, operative technique, and applications

OBJECTIVE

Side-to-Side microvascular anastomosis is a revascularization technique used to create an artificial conduit between two similar adjacent vessels. This technique is used for microsurgical clipping of aneurysms, when indicated. It is important to study the angiographic results, both immediate and long term, along with the clinical outcomes and indications of the procedure.

METHODS

Fifteen patients who had this procedure over a fourteen-year period were reviewed for patency of bypass by intra-arterial digital subtraction angiography (DSA) and computed tomographic arteriograms (CTA) and their clinical outcomes were studied. The mean age of the study group was 53.4 years and mean angiographic follow up period was 14 months.

RESULTS

All surviving patients (14 patients) had patent anastomosis with good clinical outcomes. None of the patients developed a clinically manifested stroke due to the procedure, while one had a small asymptomatic infarct detected post operatively.

CONCLUSION

This technique is a useful and durable solution for correcting critical stenosis or complete occlusion of the vessels, while clipping intracranial aneurysms.

High flow extra-cranial to intra-cranial bypass for complex internal carotid aneurysms

Cerebral revascularisation with extracranial - intracranial (EC-IC) bypass is generally indicated in patients with complex anterior circulation aneurysms who have failed parent artery occlusion. We report on the process and outcome of our early experience of performing high flow bypass in patients with complex anterior circulation aneurysms. We have reviewed patients who have undergone an EC-IC bypass for treatment of complex anterior circulation aneurysms, and report our outcome on graft patency, surgical complications, discharge destination, and obliteration rates. Nine patients that underwent 11 bypasses are described. Seven patients had a giant saccular aneurysm of the carotid, and these were all obliterated on post-operative imaging. Two patients presenting with an intracranial carotid dissection required trapping of the diseased segment following the bypass. The overall graft patency rate was 88%. One patient developed a post operative subdural collection (managed conservatively), and one patient required early graft revision. Discharge destination was home in 8/9 patients. There was no mortality. Although EC-IC bypass is a technically challenging procedure, it provides a valuable treatment option for patients with complex anterior circulation aneurysms. Good graft patency rates can be achieved with low surgical morbidity in patients with a disease process that otherwise attracts a highly unfavourable natural history.

Surgical management of aneurysmal subarachnoid hemorrhage

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

Slowly progressive neuronal death associated with postischemic hyperperfusion in cortical laminar necrosis after high-flow bypass for a carotid intracavernous aneurysm

The authors report a rare case of slowly progressive neuronal death associated with postischemic hyperperfusion in cortical laminar necrosis after radial artery/external carotid artery-middle cerebral artery bypass graft surgery for an intracavernous carotid artery aneurysm. Under barbiturate protection, a 69-year-old man underwent high-flow bypass surgery combined with carotid artery sacrifice for a symptomatic intracavernous aneurysm. The patient became restless postoperatively, and this restlessness peaked on postoperative Day (POD) 7. Diffusion-weighted and FLAIR MR images obtained on PODs 1 and 7 revealed subtle cortical hyperintensity in the temporal cortex subjected to temporary occlusion. On POD 13, (123)I-iomazenil ((123)I-IMZ) SPECT clearly showed increased distribution on the early image and mildly decreased binding on the delayed image with count ratios of the affected-unaffected corresponding regions of interest of 1.23 and 0.84, respectively, suggesting postischemic hyperperfusion. This was consistent with the finding on (123)I-iodoamphetamine SPECT. Of note, neuronal density in the affected cortex on the delayed (123)I-IMZ image further decreased to the affected/unaffected ratio of 0.44 on POD 55 during the subacute stage when characteristic cortical hyperintensity on T1-weighted MR imaging, typical of cortical laminar necrosis, was emerging. The affected cortex showed marked atrophy 8 months after the operation despite complete neurological recovery. This report illustrates, for the first time, dynamic neuroradiological correlations between slowly progressive neuronal death shown by (123)I-IMZ SPECT and cortical laminar necrosis on MR imaging in human stroke.

Novel technique to improve vessel mismatch when using saphenous vein bypass grafts for intracranial revascularization procedures

Cerebral bypass procedures in the posterior circulation are difficult to perform and are considered to be high-risk surgery. Venous grafts, like that formed using the saphenous vein (SV), are simple to obtain without posing a high risk of morbidity. The main disadvantage of these high-flow grafts is the mismatch in vessel diameter between donor and recipient vessels in the posterior circulation. The authors performed a retrospective case study based of data from intraoperative video, patient charts, axial images, and cerebral angiograms. They treated a 66-year-old man who presented with a giant aneurysm of the vertebrobasilar junction and another large aneurysm of the basilar tip. They chose to create a vertebral artery (VA)-superior cerebellar artery anastomosis with a tapered-down SV graft. It was necessary to reengineer the SV graft to include a gentle taper that would allow for this anastomosis. The vein was incised for a distance of 2.5 cm. A triangular section of the vein, 2 mm at the base and 20 mm high, was then excised from the opened end of the SV. The 2.5-cm-long venotomy was then closed with interrupted 9-0 Prolene sutures creating a gentle taper to the vein down to ~ 2.5 mm in diameter. Thereafter, the authors created a standard end-to-side anastomosis of the VA to the SV with 8-0 Prolene. Postoperatively both VAs were obliterated with coils just proximal to the vertebrobasilar aneurysm. The bypass was patent; after a prolonged stay in the intensive care unit, the patient recovered gradually. This technique of linear venotomy along the distal 2.5 cm of the vein and subsequent tapering down of the diameter diminishes the circumference of the distal end of the graft, facilitating bypass to smaller vessels. This is a novel and feasible technique to eliminate vessel mismatch in cerebral bypass procedures in the difficult accessible vessels of the posterior circulation.

Flow replacement bypass for aneurysms: decision-making using intraoperative blood flow measurements

PURPOSE

There is much debate regarding the optimal strategy for extracranial-intracranial (EC-IC) bypass for complex aneurysms. We introduce the concept of a flow replacement bypass which aims to compensate for loss of flow in the efferent vessels of the aneurysm. The strategy to achieve this utilizes direct intraoperative flow measurements to guide optimal revascularization by matching graft flow to demand.

METHODS

We reviewed all EC-IC bypass cases performed over a 6-year period. We identified cases in which intraoperative flow measurements using an ultrasonic flow probe were utilized to determine the revascularization strategy and analyzed the decision-making paradigm.

RESULTS

Twenty-three cases were analyzed. For terminal aneurysms, flow measurement in the affected vessel at baseline predicted the flow required for full replacement: middle cerebral artery (MCA), 50 +/- 25 cc/min (n = 9); posterior inferior cerebellar artery (PICA), 13 +/- 7 cc/min (n = 4); posterior cerebral artery (PCA), 33 cc/min (n = 1); and superior cerebellar artery (SCA), 10 cc/min (n = 1). For proximal internal carotid artery (ICA) aneurysms (n = 8), the flow deficit from baseline during carotid temporary occlusion was measured (26 +/- 18 cc/min, an average of 44% drop from baseline). The adequacy of flow from the superficial temporal artery (STA) or occipital artery (OA), when available, was assessed prior to bypass, and STA, OA, or vein interposition grafts were used accordingly. Measurement of bypass flow following anastomosis confirmed not only patency but sufficient flow in all cases: MCA 50 +/- 25 cc/min, PICA 18 +/- 9 cc/min, PCA 64 cc/min, SCA 12 cc/min, ICA 36 +/- 25 cc/min (STA), and >200 cc/min (vein).

CONCLUSIONS

Direct intraoperative measurement of flow deficit in aneurysm surgery requiring parent vessel sacrifice can guide the choice of flow replacement graft and confirm the subsequent adequacy of bypass flow.

Emergency extracranial-intracranial bypass surgery for acute ischemic stroke

Object

The purpose of this study was to evaluate the safety and efficacy of urgent extracranial-intracranial (ECIC) bypass in the management of intracranial cerebrovascular disease and acute cerebral ischemic injury in carefully selected patients.

Methods

The authors reviewed the medical records and neuroimaging studies in 13 consecutive patients who underwent urgent surgical cerebral revascularization to treat acute cerebral ischemia. None were thought to be appropriate candidates for endovascular therapy. The patients' ages ranged from 21 to 65 years (mean 41.2 years). The mean follow-up review was 3.5 years, and no patient was lost to follow-up.

Results

Preoperative angiographic evaluation identified critical narrowing of the supraclinoid internal carotid artery (ICA) in 8 patients, the M1 segment of the middle cerebral artery (MCA) in 3, and the cervical/petrous ICA in 2. All patients had progressive, refractory symptoms associated with enlarging areas of infarction on diffusion weighted MR imaging, despite maximal medical therapy, which included anticoagulation and antiplatelet agents, blood pressure elevation, and fluid resuscitation. All patients underwent superficial temporal artery–MCA anastomosis on an urgent basis. In every case, the bypass prevented further stroke progression. In 2 cases, revascularization was followed by rapid, dramatic improvement of preoperative neurological deficits.

Conclusions

In the authors' experience, emergency EC-IC bypass in patients with acute ischemic injury was both safe and effective. This population was characterized by relatively young patients with severely limited collateral circulation. In this series of 13 carefully selected patients, bypass was successful in arresting progression of stroke, and in some cases resulted in rapid neurological improvement.

Giant Aneurysm Clipping Under Protection of an Excimer Laser–Assisted Non-occlusive Anastomosis Bypass

OBJECTIVE

To define the safety and clinical value of giant aneurysm clipping under protection of an excimer laser–assisted non-occlusive anastomosis (ELANA) bypass.

METHODS

We report 32 patients with an uncoilable intracerebral giant aneurysm, operated on with the aid of an ELANA protective bypass between January 1, 1994, and January 1, 2008. We retrospectively collected data from patient records. Follow-up data were updated by telephone interview. We defined a favorable outcome as a successfully treated aneurysm and a better or equal postoperative modified Rankin scale (mRS) score compared with the preoperative mRS.

RESULTS

In total 33 bypasses were constructed, of which 31 (94%) were patent during the rest of the procedure. The first failed bypass was salvaged during a second procedure. Of the second failed bypass, the ELANA anastomosis could be reused during second bypass surgery. All 32 aneurysms could be treated. The bypasses served as protection during temporary parent vessel occlusion (n = 24, 75%), control during aneurysm rupture (n = 3, 9%), and in all patients as an indicator for recipient artery narrowing during clip placement. Four bypasses (12%) eventually had to partially (n = 3) or fully (n = 1) replace recipient artery flow at the end of surgery. Postoperatively, 3 patients (9%) had a hemorrhagic complication and 2 patients (6%) had an ischemic complication. At long-term follow-up (mean, 6.1 ± 3.4 y), 28 patients (88%) had a favorable functional outcome.

CONCLUSION

The ELANA protective bypass is a safe and useful instrument for the treatment of these difficult aneurysms.