De novo large fusiform posterior circulation intracranial aneurysm presenting with subarachnoid hemorrhage 7 years after therapeutic internal carotid artery occlusion: case report and review of the literature

Treatment of Unruptured Large and Giant Paraclinoid Aneurysms in Japan at the Time of Flow Diverter Introduction: A Nationwide, Multicenter Survey by the Japanese Society on Surgery for Cerebral Stroke

OBJECTIVE

Large or giant paraclinoid aneurysms have been treated with various strategies, including clipping, coiling, and parent artery occlusion (PAO). In addition, flow diverters (FDs) have been introduced for the management of these aneurysms. The aim of this study was to examine the management of unruptured large/giant paraclinoid aneurysms in Japan when FDs were being introduced by a nationwide survey.

METHODS

A total of 576 unruptured large/giant paraclinoid aneurysms treated in Japan between January 2012 and December 2016 were retrospectively studied.

RESULTS

Half of the large paraclinoid aneurysms were treated by coiling (50.3%), whereas giant aneurysms were occluded mainly by PAO (51.4%). A high nearly complete occlusion rate was achieved with clipping (94.1%), coiling (85.9%), PAO (82.4%), and FDs (77.6%). Coiling had higher risks of recurrence (28.3%) and retreatment (20.3%). Major procedure-related complications were observed in 9.7%. Ischemic complications were common in PAO (9.5%), with cranial nerve symptoms common in clipping (10.9%). All treatment modalities achieved good clinical outcomes (93.5%-96.6%). Although not significant, pre-existing visual disturbance improved most frequently by clipping (53.7%), but also worsened most frequently by clipping (24.4%). Consequently, FD achieved a high occlusion rate with minimal complication and retreatment rates.

CONCLUSIONS

All treatment modalities offer high rates of complete occlusion and good clinical outcomes. Coiling has the disadvantage of high rates of recurrence and retreatment. Clipping and PAO have the disadvantage of a high rate of major procedure-related complications; however, PAO can provide comparable treatment outcomes even in cases with refractory giant aneurysms. FDs are the optimal choice for the management for large/giant paraclinoid aneurysms due to its safety and efficacy.

Reconstructive Endovascular Treatment of Compensative-Flow-Related Posterior Circulation Aneurysms With Anterior Circulation Artery Occlusion

BACKGROUND AND OBJECTIVES

The aim of this study was to delineate the reconstructive endovascular treatment and periprocedural management of compensative-flow-related posterior circulation aneurysms with anterior circulation artery occlusion.

METHODS

A total of 87 patients were enrolled in this retrospective double-center cohort study from May 2011 to November 2023. The baseline demographics, aneurysm characteristics, etiology and status of anterior circulation artery occlusion, treatment modalities, anesthesia management, complications, and clinical and angiographic outcomes of the patients were retrospectively analyzed in this study.

RESULTS

Atherosclerosis and moyamoya disease were found to be the two main etiologies of anterior circulation artery occlusion. The mean American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology scores were significantly higher in patients with posterior communicating artery trunk collaterals than those with posterior cerebral artery pial collaterals ( P < .05). Treatment strategies included stent-assisted coiling (55, 63.2%), standard coiling (22, 25.3%), and flow diversion or flow diversion-assisted coiling (8, 9.2%). The overall rate of procedure-related ischemic and hemorrhagic complications (10.3%) was considered acceptable. The ischemic complication was significantly associated with a >20% drop in mean arterial pressure ( P < .05) during the procedure. Finally, 86.2% of all patients showed a modified Rankin Scale score of 0 to 2 at the final clinical follow-up.

CONCLUSION

Our study indicates that reconstructive endovascular treatments are feasible and effective strategies for compensative-flow-related posterior circulation aneurysms with anterior circulation artery occlusion. However, these treatments are associated with a risk of periprocedural ischemic complications, which can be reduced by collateral arterial assessment, appropriate periprocedural anesthesia management, and antiplatelet treatment.

Treatment of Unruptured Large and Giant Carotid Cavernous Aneurysms in Japan at the Time of Flow Diverter Introduction: A Nationwide, Multicenter Survey by the Japanese Society on Surgery for Cerebral Stroke

BACKGROUND

Flow diverters (FDs) were introduced for management of large or giant cavernous carotid aneurysms (CCAs) in addition to conventional modalities, dramatically changing treatment strategies. This study examined the management of unruptured large/giant CCAs in Japan when FDs were being introduced using a nationwide survey.

METHODS

A total of 540 unruptured large/giant CCAs treated at neurosurgical teaching departments in Japan between 2012 and 2016 were retrospectively studied.

RESULTS

Large CCAs were treated equally by parent artery occlusion (PAO), FD, and coiling, but giant aneurysms were occluded mainly by PAO. PAO was combined with revascularization in most cases. The nearly complete obliteration rate at final follow-up was higher after PAO (92.4%) than after FD (60.1%) and coiling (70.3%), and PAO was the most effective for ophthalmoparesis. Coiling had higher risks of recurrence and retreatment. Procedure-related major complications were observed in 9.6%. Cranial nerve symptoms were the most common complications, with coiling having significantly higher risks. All treatment modalities achieved good clinical outcomes (92.1%-96.1%); however, 5 delayed rupture cases were observed (1 PAO, 4 FD), resulting in 5 deaths (1 PAO, 1 FD).

CONCLUSIONS

The nationwide survey reported here determined the status of treatment for unruptured large/giant CCAs in Japan when FDs were being introduced. Because PAO has disadvantages including the long-term hemodynamic effects of ICA occlusion, reconstructive treatment using FDs is optimal for this type of aneurysm; however, PAO can be an option in selected cases given the higher rates of complete occlusion and symptom improvement.

The Presence of Coexisting Internal Carotid Artery Occlusion is the Main Associated Factor of Posterior Cerebral Artery Aneurysm Rupture

BACKGROUND

Posterior cerebral artery (PCA) aneurysms are rare but clinically significant due to their critical location and complex management. The risk factor of the PCA aneurysms rupture remains unclear. This study aimed to investigate the associated factor of PCA aneurysms rupture in a large Chinese cohort.

METHODS

We conducted a cross-sectional study including patients diagnosed with PCA aneurysms between January 2017 and December 2020. The study population comprised 143 patients, with 95 in the ruptured group and 48 in the unruptured group. Data on demographic characteristics, aneurysm features, medical history, and treatment outcomes were collected and analyzed using SPSS 27.0. Univariate and multivariate logistic regression analyses were performed to identify associated factors for PCA aneurysm rupture.

RESULTS

The presence of coexisting internal carotid artery occlusion (ICAO) was identified as an independent associated factor for PCA aneurysm rupture (odds ratio [OR] = 4.74, 95% confidence interval [CI] 1.22-18.42, P = 0.03). Ischemic stroke (OR=0.44, 95% CI: 0.20-0.97, P = 0.02) and multiple aneurysms (OR=0.41, 95% CI: 0.19-0.87, P = 0.04) were found to be potential protective factors against rupture. The study also revealed a higher incidence of ICAO in the ruptured group (18.9%) compared to the unruptured group (6.3%), indicating a significant association with aneurysm rupture.

CONCLUSIONS

This is the first multicenter study to highlight the coexistence of ICAO as a major associated factor for PCA aneurysm rupture in the Chinese population.

Ruptured brain aneurysm-induced subarachnoid hemorrhage with concurrent myocardial infarction in a rhesus monkey (Macaca mulatta)

Brain aneurysm ruptured subarachnoid hemorrhages (SAH) are extremely rare except in humans. This study described a SAH caused by a ruptured anterior communication artery aneurysm and concurrent myocardial infarction, along with pneumonia and intestinal obstruction in a rhesus monkey, which is rather rare in animal experiments.

Flow-related posterior cerebral artery aneurysms with internal carotid artery occlusions: An institutional series

BACKGROUND

Aneurysm formation after internal carotid artery (ICA) occlusion has been described in animal models and human case series with alteration of cerebral blood flow dynamics considered an aetiological risk factor. Such de novo aneurysms have seldom been described in the posterior cerebral artery (PCA) with the majority observed in the anterior circulation collateral pathways.

METHODS

We retrospectively reviewed our institutional database of posterior circulation aneurysms in patients with iatrogenic, atherosclerotic or congenital ICA occlusions. A comprehensive review of the online literature using the PubMed and Medline databases was performed to identify previous cases of PCA aneurysms that were considered 'flow-related'.

RESULTS

We present five patients with symptomatic or ruptured PCA aneurysms with ICA occlusions. Age at presentation ranged from 21-58 and aneurysm size from 3-12 mm. All cases had angiographic evidence of posterior-anterior flow via the ipsilateral posterior communicating artery (PComA). The clinical presentation, diagnostic imaging and management strategies are further discussed. A literature review identified only two previous reported cases.

CONCLUSION

To our knowledge this is the first single centre series of posterior circulation aneurysms in patients with ICA occlusions that are considered to be 'flow-related.' The natural history of these rare lesions is unclear and the best management and surveillance strategy requires a patient-tailored approach by an experienced neurovascular team.

Hemodynamic characteristics associated with cerebral aneurysm formation in patients with carotid occlusion

OBJECTIVE

The pathogenesis of cerebral aneurysms in patients with internal carotid artery (ICA) occlusion is hypothesized to be hemodynamic. For the first time, the authors quantify the hemodynamic characteristics associated with aneurysm formation in patients with ICA occlusion.

METHODS

Records of patients with unilateral ICA stenosis or occlusion ≥ 90% who underwent hemodynamic assessment before treatment using quantitative MR angiography were retrospectively reviewed. The patients were classified into 2 groups based on the presence or absence of aneurysms. The hemodynamic parameters of flow volume rate, flow velocity, and wall shear stress (WSS) were measured in each vessel supplying collateral flow-bilateral A1 segments and bilateral posterior communicating arteries-and then compared between the groups.

RESULTS

A total of 36 patients were included (8 with and 28 without aneurysms). The mean flow (72.3 vs 48.9 ml/min, p = 0.10), flow velocity (21.1 vs 12.7 cm/sec, p = 0.006), and WSS (22.0 vs 12.3 dynes/cm2, p = 0.003) were higher in the A1 segment contralateral to the side of the patent ICA in patients with versus without aneurysms. All de novo or growing aneurysms in our cohort were located on the anterior communicating artery (ACoA) or P1 segment.

CONCLUSIONS

Flow velocity and WSS are significantly higher across the ACoA in patients who harbor an aneurysm, and de novo or growing aneurysms are often located on collateral vessels. Thus, robust primary collaterals after ICA occlusion may be a contributing factor in cerebral aneurysm formation.

[Proximal clipping of a large fusiform aneurysm of the A2 segment of the left anterior cerebral artery with awakening of the patient (a case report and literature review)]

Arterial aneurysms of the A2 segment are very rare (<1%) peripheral aneurysms of the anterior cerebral artery (ACA) territory. Usually, these are saccular aneurysms; there are single reports of fusiform aneurysms of this location. Surgical treatment of these aneurysms involves both microsurgical and endovascular interventions. In the presented case, we used deconstructive surgery (proximal clipping of the aneurysm) with intraoperative awakening of the patient, which verified sufficient collateral blood flow. In the case of focal deficit development, we planned to simultaneously perform an interarterial anastomosis between the A3 segments of the right and left ACAs.

Site-specific elevation of interleukin-1β and matrix metalloproteinase-9 in the Willis circle by hemodynamic changes is associated with rupture in a novel rat cerebral aneurysm model

The pathogenesis of subarachnoid hemorrhage remains unclear. No models of cerebral aneurysms elicited solely by surgical procedures and diet have been established. Elsewhere we reported that only few rats in our original rat aneurysm model manifested rupture at the anterior and posterior Willis circle and that many harbored unruptured aneurysms at the anterior cerebral artery-olfactory artery bifurcation. This suggests that rupture was site-specific. To test our hypothesis that a site-specific response to hemodynamic changes is associated with aneurysmal rupture, we modified our original aneurysm model by altering the hemodynamics. During 90-day observation, the incidence of ruptured aneurysms at the anterior and posterior Willis circle was significantly increased and the high incidence of unruptured aneurysms at the anterior cerebral artery-olfactory artery persisted. This phenomenon was associated with an increase in the blood flow volume. Notably, the level of matrix metalloproteinase-9 associated with interleukin-1β was augmented by the increase in the blood flow volume, suggesting that these molecules exacerbated the vulnerability of the aneurysmal wall. The current study first demonstrates that a site-specific increase in interleukin-1β and matrix metalloproteinase-9 elicited by hemodynamic changes is associated with rupture. Our novel rat model of rupture may help to develop pharmaceutical approaches to prevent rupture.

Rationale for graft selection in patients with complex internal carotid artery aneurysms treated with extracranial to intracranial high-flow bypass and therapeutic internal carotid artery occlusion

OBJECTIVE After internal carotid artery (ICA) sacrifice without revascularization for complex aneurysms, ischemic complications can occur. In addition, hemodynamic alterations in the circle of Willis create conditions conducive to the formation of de novo aneurysms or the enlargement of existing untreated aneurysms. Therefore, the revascularization technique remains indispensable. Because vessel sizes and the development of collateral circulation are different in each patient, the ideal graft size to prevent low flow-related ischemic complications (LRICs) in external carotid artery (ECA)-middle cerebral artery (MCA) bypass with therapeutic ICA occlusion (ICAO) has not been well established. Authors of this study hypothesized that the adequate graft size could be calculated from the size of the sacrificed ICA and the values of MCA pressure (MCAP) and undertook an investigation in patients with complex ICA aneurysms treated with ECA-graft-MCA bypass and therapeutic ICAO. METHODS In the period between July 2006 and January 2016, 80 patients with complex ICA aneurysms were treated with ECA-MCA bypass and therapeutic ICAO. Preoperative balloon test occlusion (BTO) was performed, and the BTO pressure ratio was defined as the mean stump pressure/mean preocclusion pressure. Low flow-related ischemic complications were defined as new postoperative neurological deficits and ipsilateral cerebral blood flow reduction. Initial MCAP (iMCAP), MCAP after clamping the ICA (cMCAP), and MCAP after releasing the graft (gMCAP) were intraoperatively monitored. The MCAP ratio was defined as gMCAP/iMCAP. Based on the Hagen-Poiseuille law, the expected MCAP ratio ([expected gMCAP]/iMCAP) was hypothesized as follows: (1 - cMCAP/iMCAP)(graft radius/ICA radius)² + (cMCAP/iMCAP). Correlations between the BTO pressure ratio and cMCAP/iMCAP, and between the actual and expected MCAP ratios, were evaluated. Risk factors for LRICs were also evaluated. RESULTS The mean BTO pressure ratio was significantly correlated with the mean cMCAP/iMCAP (r = 0.68, p < 0.0001). The actual MCAP ratio correlated with the expected MCAP ratio (r = 0.43, p < 0.0001). If the expected MCAP ratio was set up using the BTO pressure ratio instead of cMCAP/iMCAP (BTO-expected MCAP ratio), the mean BTO-expected MCAP ratio significantly correlated with the expected MCAP ratio (r = 0.95, p < 0.0001). During a median follow-up period of 26.1 months, LRICs were observed in 9 patients (11%). An actual MCAP ratio < 0.80 (p = 0.003), expected MCAP ratio < 0.80 (p = 0.001), and (M₂ radius/graft radius)² < 0.49 (p = 0.002) were related to LRICs according to the Cox proportional-hazards model. CONCLUSIONS Data in the present study indicated that it was important to use an adequate graft to achieve a sufficient MCAP ratio in order to avoid LRICs and that the adequate graft size could be evaluated based on a formula in patients with complex ICA aneurysms treated with ICAO.

Comparison of the flow diverter and stent-assisted coiling in large and giant aneurysms: safety and efficacy based on a propensity score-matched analysis

OBJECTIVES

The flow diverter (FD) is a device aimed at reconstructing the parent artery and occluding an aneurysm. We performed a propensity score-matched analysis to compare safety and efficacy between the FD and stent-assisted coiling.

METHODS

A database review was conducted to identify patients with large and giant unruptured aneurysms (aneurysms located in the ACA, MCA, or PCA were excluded) treated with the FD or stent-assisted coiling. A propensity score, representing the probability of using the FD, was generated for each aneurysm using the relevant patient and aneurysmal variables. Angiographic results, complications, and clinical outcomes were compared.

RESULTS

Forty-five aneurysms treated with the FD (FD alone: 32; FD+Coils: 13) and 45 treated with stent-assisted coiling were matched. The rate of complete occlusion was significantly (P = 0.0002) higher in the FD cohort than the conventional stent cohort at the 6-month follow-up. The FD cohort achieved greater improvement (P < 0.0001) and a lower rate of recurrence (P = 0.0001). The rate of periprocedural complications was similar, as was the proportion of patients who attained mRS ≤ 2 at discharge and at the 6-month follow-up.

CONCLUSIONS

Our findings provide reliable evidence demonstrating that the FD may be a preferred treatment option for large and giant unruptured aneurysms.

KEY POINTS

• Flow Diverter provided a higher complete occlusion rate at 6-month follow-up. • Flow Diverter achieved more progress occlusion and less recurrence. • Compared with the conventional stents, procedure-related morbidity of Flow Diverter was similar. • Flow Diverter is a preferred treatment for large and giant unruptured aneurysms.

Hypertension and Estrogen Deficiency Augment Aneurysmal Remodeling in the Rabbit Circle of Willis in Response to Carotid Ligation

Increased cerebral blood flow has been shown to induce pathological structural changes in the Circle of Willis (CoW) in experimental models. Previously, we reported flow-induced aneurysm-like remodeling in the CoW secondary to flow redistribution after bilateral common carotid artery (CCA) ligation in rabbits. In the current study, we tested the hypothesis that loading rabbits with biological risk factors for vascular disease would increase flow-induced aneurysmal remodeling in the CoW. In the same series as the previously-reported bilateral CCA-ligation-alone (n  = 6) and sham surgery (n = 3) groups, eight additional female rabbits (the experimental group in this study) were subjected to two risk factors for intracranial aneurysm (hypertension and estrogen deficiency) and then bilateral CCA ligation. Upon euthanasia at 6 months, vascular corrosion casts of the CoW were created and analyzed by scanning electron microscopy for morphological changes and aneurysmal damage. In rabbits with hypertension and estrogen deficiency, arterial caliber increased throughout the CoW, similar to rabbits with CCA ligation alone. However, aneurysmal remodeling (i.e., local bulging) in the CoW was significantly greater than in CCA-ligation-only rabbits and was more widespread, presenting in regions that did not show aneurysmal changes after CCA ligation alone. Furthermore, hypertension and estrogen deficiency caused greater increases in vessel length and tortuosity. These results suggest that hypertension and estrogen deficiency make the CoW more vulnerable to flow-induced aneurysmal remodeling and tortuosity. We propose they do so by lowering the tolerance of vascular tissue to hemodynamic forces caused by CCA ligation, thus lowering the threshold necessary to incite vascular damage.

Bilateral Cavernous Carotid Aneurysms: The Growth Potential of a Contralateral Aneurysm after Therapeutic Unilateral Internal Carotid Artery Occlusion

BACKGROUND

Although the introduction of flow-diverter stents has been recognized as a major revolution in the treatment of cavernous carotid aneurysms (CCAs), therapeutic internal carotid artery occlusion (TICAO) remains a reliable procedure for alleviating symptoms caused by CCAs. However, TICAO has the potential risk of the enlargement of coexisting aneurysms that are frequently detected in CCA patients. The purpose of this study is to assess the occurrence of the enlargement of aneurysms coexisting with CCAs after TICAO.

METHODS

We reviewed medical charts of CCA patients who were managed using unilateral TICAO. Coexisting aneurysms were identified using angiograms obtained before TICAO, and imaging data in long follow-up periods were retrospectively examined to determine the extent of the enlargement after TICAO.

RESULTS

Of 12 patients with CCAs, 10 had 12 coexisting aneurysms; 5 of the coexisting aneurysms (41.7%) showed enlargement during a mean follow-up period of 8.1 years, and all enlarged aneurysms were smaller of the bilateral CCAs; the larger CCA had been managed by TICAO. Five of 6 (83.3%) patients with bilateral CCAs showed enlargement of the contralateral aneurysm after TICAO. Two contralateral CCAs showed marked enlargement after TICAO and were subsequently treated with stent-assisted coil embolization.

CONCLUSIONS

Contralateral, smaller aneurysms frequently enlarge after unilateral TICAO in patients with bilateral CCAs. The findings emphasize the importance of long-term observation after TICAO and appropriate interventions against enlarging contralateral aneurysms.

Prevention of Retrograde Blood Flow Into Large or Giant Internal Carotid Artery Aneurysms by Endovascular Coil Embolization with High-Flow Bypass: Surgical Technique and Long-Term Results

BACKGROUND

Recanalization has been reported in large or giant aneurysms of the internal carotid artery (ICA) addressed by high-flow bypass and endovascular treatment. Aneurysmal recanalization may be attributable to retrograde blood flow into the aneurysm through the ICA branches, such as the ophthalmic artery or the meningohypophyseal trunk, or through the surgically created bypass. We modified the endovascular treatment of aneurysms to prevent retrograde flow and evaluated the long-term efficacy of our method.

METHODS

We used a hybrid operative/endovascular technique to treat 5 patients with large or giant aneurysms arising from the C2-C4 segment of the ICA who presented with visual symptoms due to the mass effect of the aneurysm. To prevent retrograde flow into the aneurysm our modified endovascular treatment involves coil embolization of the aneurysmal orifice and the ICA, including the origin of the ophthalmic artery and meningohypophyseal trunk, and placement of a high-flow bypass using a radial artery graft.

RESULTS

During the 5- to 12-year follow-up period, 4 aneurysms disappeared, and the other decreased in size. There were no subarachnoid hemorrhages. All bypass grafts remained patent. Visual preservation was achieved in 2 patients; 1 patient manifested visual improvement. Although 2 patients experienced transient neurological deficits we encountered no permanent complications in this series. The final modified Rankin scale of the 5 patients was 0 or 1.

CONCLUSIONS

Prevention of retrograde flow into the aneurysm by coil embolization with high-flow bypass is a safe and effective method. It prevents the recanalization of large or giant ICA aneurysms.

Successful flow reduction surgery for a ruptured true posterior communicating artery aneurysm caused by the common carotid artery ligation for epistaxis

Background:

Carotid artery occlusion can lead to the development of rare true posterior communicating artery (PCoA) aneurysms because of hemodynamic stress on the PCoA. Surgical treatment of these lesions is challenging.

Case Description:

The authors report a case of a true PCoA aneurysm that developed and ruptured 37 years after ligation of the ipsilateral common carotid artery for epistaxis. The lesion was successfully treated with clipping of the distal M1 segment of the middle cerebral artery (MCA) after the occipital artery-radial artery free graft-MCA bypass, which led to extreme reduction in collateral flow through the PCoA. A cortical branch, located just proximal to the obliteration site, functioned as a sufficient flow outlet. The aneurysm shrank, and the patient has been doing well without any symptoms for 5 years after surgery.

Conclusions:

M1 obliteration combined with high-flow extra-intracranial bypass might be a promising option for a true PCoA aneurysm, and therapeutic design that leaves a sufficient flow outlet on the M1 is mandatory to avoid unexpected occlusion of the M1 and its perforators.

Pipeline Embolization Device for the Treatment of Intra- and Extracranial Fusiform and Dissecting Aneurysms

BACKGROUND:

Flow-diverting stents offer a promising treatment option for complex aneurysms.

OBJECTIVE:

To evaluate the safety and efficacy of the Pipeline embolization device (PED) in the treatment of fusiform and dissecting aneurysms.

METHODS:

Sixty-five consecutive patients with 69 fusiform and dissecting aneurysms underwent endovascular treatment with the use of the PED. Target vessels included the internal carotid artery (n = 28), middle cerebral artery (n = 2), anterior cerebral artery (n = 1), vertebral artery (n = 20), basilar artery (n = 17), and posterior cerebral artery (n = 1). An average of 3.0 PEDs per target vessel were deployed.

RESULTS:

Exclusion of the aneurysm(s) immediately after PED deployment was not observed. Angiographic follow-up examinations were performed in 63/65 patients (67/69 lesions). They showed complete cure of the target lesion in the first follow-up angiography (3.4 months mean interval) in 24 (36%) cases, partial elimination in 30 (45%), and no improvement in 13 (19%). After the latest follow-up (&gt;1 digital subtraction angiography, n = 49, 27.4 months mean interval) complete cure of the target lesion was observed in 33 (67%), partial elimination in 14 (29%), and no change in 2 (4%). Taking all follow-up examinations together, 39/67 (58%) aneurysms were cured. The morbidity and mortality in the entire series were 5% and 8%, respectively.

CONCLUSION:

Flow diverters offer a promising treatment option in fusiform and dissecting aneurysms. The introduction of flow diverters with different densities might help to identify the optimal amount of coverage needed given different anatomic presentations of fusiform and dissecting aneurysms.

Aneurysmal remodeling in the circle of Willis after carotid occlusion in an experimental model

Carotid occlusions are associated with de novo intracranial aneurysm formation in clinical case reports, but this phenomenon is not widely studied. We performed bilateral carotid ligation (n=9) in rabbits to simulate carotid occlusion, and sham surgery (n=3) for control. Upon euthanasia (n=3 at 5 days, n=6 at 6 months post ligation, and n=3 at 5 days after sham operation), vascular corrosion casts of the circle of Willis (CoW) were created. Using scanning electron microscopy, we quantified gross morphologic, macroscopic, and microscopic changes on the endocasts and compared findings with histologic data. At 5 days, CoW arteries of ligated animals increased caliber. The posterior communicating artery (PCom) increased length and tortuosity, and the ophthalmic artery (OA) origin presented preaneurysmal bulges. At 6 months, calibers were unchanged from 5 days, PComs further increased tortuosity while presenting segmental dilations, and the OA origin and basilar terminus presented preaneurysmal bulges. This exploratory study provides evidence that flow increase after carotid occlusion produces both compensatory arterial augmentation and pathologic remodeling such as tortuosity and saccular/fusiform aneurysm. Our findings may have considerable clinical implications, as these lesser-known consequences should be considered when managing patients with carotid artery disease or choosing carotid ligation as a therapeutic option.

Treatment of cavernous sinus aneurysms with flow diversion: results in 44 patients

BACKGROUND AND PURPOSE

Aneurysms of the cavernous segment of the ICA are difficult to treat with standard endovascular techniques, and ICA sacrifice achieves a high rate of occlusion but carries an elevated level of surgical complications and risk of de novo aneurysm formation. We report rates of occlusion and treatment-related data in 44 patients with cavernous sinus aneurysms treated with flow diversion.

MATERIALS AND METHODS

Patients with cavernous segment aneurysms treated with flow diversion were selected from a prospectively maintained data base of patients from 2009 to the present. Demographic information, treatment indications, number/type of flow diverters placed, outcome, complications (technical or clinical), and clinical/imaging follow-up data were analyzed.

RESULTS

We identified 44 patients (37 females, 7 males) who had a flow diverter placed for treatment of a cavernous ICA aneurysm (mean age, 57.2; mean aneurysm size, 20.9 mm). The mean number of devices placed per patient was 2.2. At final angiographic follow-up (mean, 10.9 months), 71% had complete occlusion, and of those with incomplete occlusion, 40% had minimal remnants (<3 mm). In symptomatic patients, complete resolution or significant improvement in symptoms was noted in 90% at follow-up. Technical complications (which included, among others, vessel perforation in 4 patients, groin hematoma in 2, and asymptomatic carotid occlusion in 1) occurred in approximately 36% of patients but did not result in any clinical sequelae immediately or at follow-up.

CONCLUSIONS

Our series of flow-diversion treatments achieved markedly greater rates of complete occlusion than coiling, with a safety profile that compares favorably with that of carotid sacrifice.

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.