Zhao et al., conducted a retrospective analysis of consecutive 111 patients with a ruptured very small anterior communicating artery aneurysm treated with endovascular coiling or surgical clipping in our single center. Very small aneurysms were defined as aneurysm maximal size ≤ 3.0 mm. Patients were grouped into coiling and clipping groups. Baseline characteristics, postoperative complications, clinical outcomes were compared between the 2 groups.
Forty six (41.1%) patients underwent successfully coiling, and 65 (58.0%) patients underwent surgical clipping including 2 patients who failed coiling and crossed over to surgical clipping. Mean size of ruptured ACoA aneurysms was 2.6±0.5 mm (range, 1.0-3.0 mm). Patients with smaller aneurysms (P=0.028) or A1 segment complete configuration (P=0.009) more often underwent surgical clipping and patients with A1 segment symmetric configuration more often underwent coiling (P=0.011). There were not statistically significant differences in intraoperative rupture, early rebleeding, cerebral infarction and seizure in patients treated with clipping and coiling. Clinical outcomes were similar between the 2 groups. There were no retreatment in both groups.
Patients with very small ruptured ACoA aneurysms can be safely and effectively treated with endovascular coiling. However, smaller ACoA aneurysms still require surgical clipping. A smaller aneurysm size limits the use of endovascular coiling 1).
Brain shifts following microsurgical clip ligation of anterior communicating artery aneurysms can lead to mechanical compression of the optic nerve by the clip. Recognition of this condition and early repositioning of clips can lead to reversal of vision loss.
Linzey et al., identified 3 patients with an afferent pupillary defect following microsurgical clipping of ACoA aneurysms. Different treatment options were used for each patient. All patients underwent reexploration, and the aneurysm clips were repositioned to prevent clip-related compression of the optic nerve. Near-complete restoration of vision was achieved at the last clinic follow-up visit in all 3 patients. Clip ligation of ACoA aneurysms has the potential to cause clip-related compression of the optic nerve. Postoperative visual examination is of utmost importance, and if any changes are discovered, reexploration should be considered as repositioning of the clips may lead to resolution of visual deficit 2).
An asymmetry of the A1 segment of the anterior cerebral artery (A1SA) was identified on digital subtraction angiography studies from 127 patients (21.4%) and was strongly associated with ACoAA (p < 0.0001, OR 13.7). An A1SA independently correlated with the occurrence of anterior cerebral artery infarction in patients with ACoAA (p = 0.047) and in those without an ACoAA (p = 0.015). Among patients undergoing ACoAA coiling, A1SA was independently associated with the severity of ACA infarction (p = 0.023) and unfavorable functional outcome (p = 0.045, OR = 2.4).
An A1SA is a common anatomical variation in SAH patients and is strongly associated with ACoAA. Moreover, the presence of A1SA independently increases the likelihood of ACA infarction. In SAH patients undergoing ACoAA coiling, A1SA carries the risk for severe ACA infarction and thus an unfavorable outcome. Clinical trial registration no.: DRKS00005486 (http://www.drks.de/) 3).
All cases of ruptured ACoA aneurysms treated by endovascular modalities during BRAT (2003-2007) and post-BRAT (2007-2012) were reviewed for patient and aneurysm characteristics, treatment types, and clinical and angiographic outcomes at 3-yr or last follow-up.
The BRAT ACoA cohort included 39 patients treated with coiling (excluding those crossed over to clipping). The post-BRAT cohort included 93 patients who were significantly older (mean age, 59.5 vs 52.8 yr, P = .005) than the BRAT cohort; there were no significant cohort differences in sex, Hunt and Hess grade, or mean aneurysm size. The use of balloon remodeling was significantly higher in the post-BRAT cohort (31.2% [29/93] vs 5.1% [2/39], P = .001), as was the proportion of wide-necked aneurysms treated (66.7% [62/93] vs 30.8% [12/39], P < .001). There was no significant difference in clinical outcome or retreatment rate between the 2 cohorts (P = .90 and P = .48, respectively).
ACoA lesions thought unamenable to endovascular therapy in an earlier randomized trial are now successfully coiled with increased use of adjunctive techniques, without sacrificing patient outcome or treatment durability 4).
Yang et al. retrospectively reviewed 251 patients with ACoA aneurysm who underwent surgical clipping in Beijing Tiantan Hospital between September 2011 and September 2016. Their clinical and radiologic features, as well as clinical outcomes were reviewed. In addition, univariate and multivariate logistic regression analysis was performed to identify independent risk factors for the postoperative infarction and unfavorable clinical outcomes of surgical clipping ACoA aneurysm.
The incidence of A1 segment hypoplasia was 49.8% (125 of 251 patients). Univariate analysis revealed that multiple aneurysm (P=0.025), diameter of aneurysm (P=0.040) and A1 segment hypoplasia (P=0.010) were associated with anterior cerebral artery (ACA) territories infarction, and A1 segment hypoplasia (P=0.002) is significantly correlated with unfavorable clinical outcomes of surgical clipping ACoA aneurysm. Moreover, multivariate analysis showed that multiple aneurysm (P=0.038, OR=2.571), diameter of aneurysm (P=0.034, OR=1.097) and A1 segment hypoplasia (P=0.007, OR=3.619) were strongly independent risk factors for ACA territories infarction. In addition, Hunt and Hess scores (HH) (P=0.036, OR=2.326) and A1 segment hypoplasia (P=0.002, OR=2.873) are significant independent risk factors for unfavorable clinical outcomes of surgical clipping ACoA aneurysm.
A1 segment hypoplasia is a significant independent risk factor for unfavorable clinical outcomes of surgical clipping ACoA aneurysm and ACA infarction after surgery 5).
Digital subtraction angiography images were reviewed for 204 patients with either a ruptured or an unruptured ACoA aneurysm. The ratio of the width of the larger A1 segment of the anterior cerebral artery to the smaller A1 segment was calculated. Patients with an A1 ratio greater than 2 were categorized as having A1 segment hypoplasia. The relationship of A1 segment hypoplasia to both patient and aneurysm characteristics was then assessed.
Of 204 patients that presented with an ACoA aneurysm, 34 (16.7%) were found to have a hypoplastic A1. Patients with A1 segment hypoplasia were less likely to have a history of smoking (44.1% vs 62.9%, p = 0.0410). ACoA aneurysms occurring in the setting of a hypoplastic A1 were also found to have a larger maximum diameter (mean 7.7 vs 6.0 mm, p = 0.0084). When considered as a continuous variable, increasing A1 ratio was associated with decreasing aneurysm dome-to-neck ratio (p = 0.0289). There was no significant difference in the prevalence of A1 segment hypoplasia between ruptured and unruptured aneurysms (18.9% vs 10.7%; p = 0.1605).
The results suggest that a hypoplastic A1 may affect the morphology of ACoA aneurysms. In addition, the relative lack of traditional risk factors for aneurysm formation in patients with A1 segment hypoplasia argues for the importance of hemodynamic factors in the formation of ACoA aneurysms in this anatomical setting 6).
Between January 2008 and May 2016, information on 179 consecutive patients with unruptured AcoA aneurysms was obtained and included demographic data, aneurysm features, risk factors for formation and rupture, treatment type, complications, and follow-up information. A 2-tailed t test was used for continuous data and the chi-square test for categorical variables. Statistical significance was set at P value < 0.05.
There were 76 patients 65 and older (42.5%) and 103 younger than 65 (57.5%). Conservative management was more common in older patients (67.1% vs 41.7%, P=0.001). Endovascular treatment was more commonly used in the older population (80% vs 61% of the treated aneurysms in older and younger group, P=0.16). Treatment-related complications were 8% but resulted in permanent neurological deficits in one patient (1.2%). Among conservatively treated aneurysms, three (3.2%) ruptured at follow-up resulting in patient death in two cases (2.4%). All three ruptures occurred in elderly patients.
With a modern approach that emphasizes endovascular therapy, especially in older individuals, unruptured AcoA aneurysms can be treated with a very low morbidity. Among patients with small aneurysms for which treatment was not deemed indicated or necessary, the rate of rupture at follow-up was not negligible, with 5.8% of older patients experiencing bleeding from the aneurysm 7).
Colby et al., retrospectively reviewed an IRB-approved database of patients with an aneurysm at a single institution for patients with ACoA or A1-A2 aneurysms treated with PED. Data analyzed included demographics, aneurysm characteristics, procedural details, follow-up results, and outcomes.
A total of 50 procedures were performed on 41 patients, including seven patients who underwent bilateral 'H-pipe' PED placement. The average age was 56 years and 46% of the patients were female. The average aneurysm size was 4.5 mm, and two large (>10 mm) aneurysms were treated. The vessel of origin was either the ACoA (26 aneurysms, 63%) or the A1-A2 junction (15 aneurysms, 37%). Eighteen patients (44%) had prior subarachnoid hemorrhage and 20 had previously been treated either with clipping (6 aneurysms, 15%) or coiling (14 aneurysms, 34%). Procedural success was achieved in 48/50 cases (96%) and two cases were aborted. Coils were deployed adjunctively in two cases (4%). Procedural outcomes included no deaths, one major ischemic stroke (2%), and two patients with intracranial hemorrhage (4%). Complete aneurysm occlusion was achieved in 81% of patients at 6 months and 85% of patients at last follow-up digital subtraction angiography.
The PED can be used safely and effectively in the treatment of aneurysms of the ACoA region. This represents a good alternative treatment option to microsurgical clipping and endovascular coiling 8).
A prospectively maintained single-institution neuroendovascular database was accessed to identify consecutive cases of very small (<3 mm) ruptured anterior communicating artery aneurysms treated endovascularly between 2006 and 2013.
A total of 20 patients with ruptured very small (<3 mm) anterior communicating artery aneurysms were consecutively treated with coil embolization. The average maximum diameter was 2.66 ± 0.41 mm. Complete aneurysm occlusion was achieved for 17 (85%) aneurysms and near-complete aneurysm occlusion for 3 (15%) aneurysms. Intraoperative perforation was seen in 2 (10%) patients without any clinical worsening or need for an external ventricular drain. A thromboembolic event occurred in 1 (5 %) patient without clinical worsening or radiologic infarct. Median clinical follow-up was 12 (±14.1) months and median imaging follow-up was 12 (±18.4) months.
This report describes the largest series of consecutive endovascular treatments of ruptured very small anterior communicating artery aneurysms. These findings suggest that coil embolization of very small aneurysms in this location can be performed with acceptable rates of complications and recanalization 9).
Between January 2008 and February 2015, 254 consecutive patients with 255 ACoA aneurysms were treated with coiling. We retrospectively reviewed intraoperative angiograms and medical records to identify intraprocedural rupture and thrombus formation, and re-measured aneurysm morphologies using CT angiography images. Multivariate logistic regression models were used to determine independent predictors of intraprocedural rupture and thrombus formation.
Of the 231 patients included, intraprocedural rupture occurred in 10 (4.3%) patients, and thrombus formation occurred in 15 (6.5%) patients. Patients with smaller aneurysms more often experienced intraprocedural rupture than those with larger aneurysms (3.5±1.3 mm vs 5.7±2.3 mm). Multivariate analysis showed that smaller ruptured aneurysms (p=0.003) were independently associated with intraprocedural rupture. The threshold of aneurysm size separating rupture and non-rupture groups was 3.5 mm. Multivariate analysis showed that a history of hypertension (p=0.033), aneurysm neck size (p=0.004), and parent vessel angle (p=0.023) were independent predictors of thrombus formation. The threshold of parent vessel angle separating thrombus and non-thrombus groups was 60.0°.
Ruptured aneurysms <3.5 mm were associated with an increased risk of intraprocedural rupture, and parent vessel angle <60.0°, wider-neck aneurysms, and a history of hypertension were associated with increased risk of thrombus formation during coiling of ruptured ACoA aneurysms 10).
In 33 cases among 351 cases of ruptured anterior communicating artery aneurysms treated surgically, from 1991 to 2000, the dome of aneurysm was compressed in optic pathway. In some cases, aneurysm impacted into the optic nerve that deep hollowness was found when the aneurysm sac was removed during operation. Among 33 cases, 10 cases presented with preoperative visual symptoms, such as visual dimness (5), unilateral visual field defect (2) or unilateral visual loss (3), 20 cases had no visual symptoms. Visual symptoms could not be checked in 3 cases due to the poor mental state. In 6 cases among 20 cases having no visual symptoms, optic nerve was deeply compressed by the dome of aneurysm which was seen in the surgical field. Of 10 patients who had visual symptoms, 8 showed improvement in visual symptoms within 6 months after clipping of aneurysms. In 2 cases, the visual symptoms did not recover.
Anterior communicating artery aneurysm can cause visual symptoms by compressing the optic nerve or direct rupture to the optic nerve with focal hematoma formation. Park et al., emphasize that cerebral vascular study is highly recommended to detect intracranial aneurysm before its rupture in the case of normal CT findings with visual symptoms and frequent headache 11).
A prospective study included 223 patients who were divided into three groups: Group A (83 microsurgically treated patients, 1990-1995); Group B (103 microsurgically treated patients, 1996-2000); and Group C (37 patients treated with Guglielmi Detachable Coil [GDC] embolization, 1996-2000). Depending on the direction in which the aneurysm fundus projected, the authors attempted to apply microsurgical treatment to Type 1 aneurysms (located in front of the axis formed by the pericallosal arteries). They proposed the most adapted procedure for Type 2 aneurysms (located behind the axis of the pericallosal arteries) after discussion with the neurovascular team, depending on the physiological status of the patient, the treatment risk, and the size of the aneurysm neck. In accordance with the classification of Hunt and Hess, the authors designated those patients with unruptured aneurysms (Grade 0) and some patients with ruptured aneurysms (Grades I-III) as having good preoperative grades. Patients with Grade IV or V hemorrhages were designated as having poor preoperative grades. By performing routine angiography and computerized tomography scanning, the causes of unfavorable outcome (Glasgow Outcome Scale [GOS] score < 5) and the morphological results (complete or incomplete occlusion) were analyzed. Overall, the clinical outcome was excellent (GOS Score 5) in 65% of patients, good (GOS Score 4) in 9.4%, fair (GOS Score 3) in 11.6%, poor (GOS Score 2) in 3.6%, and fatal in 10.3% (GOS Score 1). Among 166 patients in good preoperative grades, an excellent outcome was observed in 134 patients (80.7%). The combined permanent morbidity and mortality rate accounted for up to 19.3% of patients. The rates of permanent morbidity and death that were related to the initial subarachnoid hemorrhage were 6.2 and 1.5% for Group A, 6.6 and 1.3% for Group B, and 4 and 4% for Group C, respectively. The rates of permanent morbidity and death that were related to the procedure were 15.4 and 1.5% for Group A, 3.9 and 0% for Group B, and 8 and 8% for Group C, respectively. When microsurgical periods were compared, the rate of permanent morbidity or death related to microsurgical complications decreased significantly (Group A, 11 patients [16.9%] and Group B, three patients [3.9%]); Fisher exact test, p = 0.011) from the period of 1990 to 1995 to the period of 1996 to 2000. The combined rate of morbidity and mortality that was related to the endovascular procedure (16%) explained the nonsignificance of the different rates of procedural complications for the two periods, despite the significant decrease in the number of microsurgical complications. Among 57 patients in poor preoperative grade, an excellent outcome was observed in 11 patients (19.3%); however, permanent morbidity (GOS Scores 2-4) or death (GOS Score 1) occurred in 46 patients (80.7%). With regard to the correlation between vessel occlusion (the primary microsurgical complication) and the morphological characteristics of aneurysms, only the direction in which the fundus projected appeared significant as a risk factor for the microsurgically treated groups (Fisher exact test: Group A, p = 0.03; Group B, p = 0.002). The difference between endovascular and microsurgical procedures in the achievement of complete occlusion was considered significant (chi2 = 6.13, p = 0.01).
The direction in which the fundus projects was chosen as the morphological criterion between endovascular and surgical methods. The authors propose that microsurgical clip application should be the preferred option in the treatment of ACoA aneurysms with anteriorly directed fundi and that endovascular packing be selected for those lesions with posteriorly directed fundi, depending on morphological criteria 12).