A1 Hypoplasia Research Articles

Surgical outcomes of patients after treatment of ruptured anterior communicating artery aneurysms: \u201creal-world\u201d evidence from southern Thailand

BackgroundAnterior communicating artery (AComA) aneurysm rupture is the most common cause of subarachnoid hemorrhage worldwide. In this study, we aimed to determine the factors associated with a poor clinical outcome in patients with ruptured AComA aneurysms undergoing microsurgical clipping.MethodsWe retrospectively reviewed the clinical and radiologic features as well as clinical outcomes of 150 consecutive patients with ruptured AComA aneurysm who underwent surgical clipping during the 11-year study period. Logistic regression analysis was performed to identify independent factors associated with unfavorable clinical outcomes (defined as a modified Rankin scale score of 3–6).ResultsThe study included 83 male and 67 female patients, with a mean age of 51.3 ± 11.5 years. At admission, most of the patients had good neurological status, including 97 (64.7%) patients with a Hunt and Hess grade of 1 or 2 and 109 (72.6%) patients with a World Federation of Neurosurgical Societies grade of 1 or 2. Unfavorable outcomes at 6 months were observed in 23 (22.0%) patients, and the 6-month mortality rate was 8.0%. Multivariate analysis showed that preoperative intraventricular hemorrhage (odds ratio [OR], 19.66; 95% confidence interval [CI], 5.10–75.80; P < 0.001), A1 hypoplasia (OR, 8.90; 95% CI, 2.82–28.04; P < 0.001), and postoperative cerebral infarction (OR, 3.21; 95% CI, 1.16–8.88; P = 0.025) were strong independent risk factors for unfavorable outcomes.ConclusionsProper management of preoperative intraventricular hemorrhage, A1 hypoplasia, and intensive care for postoperative brain infarction are warranted for improved surgical outcomes in patients with ruptured AComA aneurysm undergoing surgical clipping.

An MRI study of typical anatomical variants of the anterior communicating artery complex.

This magnetic resonance imaging study examined the most frequent anatomical variants of the anterior communicating artery (ACoA) complex of the cerebral arterial circle, and aimed to determine whether they were associated with ACoA complex aneurysm. The study enrolled 669 patients. Using three-dimensional time-of-flight magnetic resonance angiography, 617 patients were classified into the following groups based on the anatomical variation in the ACoA complex: no ACoA complex anomaly; ACoA complex aneurysm; and vascular anomaly distant from the cerebral arterial circle. Of the 617 classified subjects, the classical anatomical description applied to 48.73% in the no ACoA complex anomaly group and 37.5% in the ACoA complex aneurysm group. One variant (left anterior cerebral artery segment A1 hypoplasia) was significantly more frequent in the ACoA complex aneurysm group. There was no sex difference in the prevalence of any variant. Anatomical variants of the ACoA complex of the cerebral arterial circle were found in almost half of the subjects. One variant seemed to be associated with a higher likelihood of an aneurysm, but causality could not be inferred.

Limitations of median nerve somatosensory evoked potential monitoring during carotid endarterectomy.

Hypoperfusion during carotid artery cross-clamping (CC) for carotid endarterectomy (CEA) may result in the major complication of perioperative stroke. Median nerve somatosensory evoked potential (MNSSEP) monitoring, which is an established method for the prediction of cerebral ischemia, has low sensitivity in detecting such hypoperfusion. In this study the authors sought to explore the limitations of MNSSEP monitoring compared to tibial nerve somatosensory evoked potential (TNSSEP) monitoring for the detection of CC-related hypoperfusion. The authors retrospectively analyzed data from patients who underwent unilateral CEA with routine shunt use. All patients underwent preoperative magnetic resonance angiography and were monitored for intraoperative cerebral ischemia by using MNSSEP, TNSSEP, and carotid stump pressure during CC. First, the frequency of MNSSEP and TNSSEP changes during CC were analyzed. Subsequently, variables related to stump pressure were determined by using linear analysis and those related to each of the somatosensory evoked potential (SSEP) changes were determined by using logistic regression analysis. A total of 94 patients (mean age 74 years) were included in the study. TNSSEP identified a greater number of SSEP changes during CC than MNSSEP (20.2% vs 11.7%; p < 0.05). Linear regression analysis demonstrated that hypoplasia of the contralateral proximal segment of the anterior cerebral artery (A1 hypoplasia) (p < 0.01) and hypoplasia of the ipsilateral precommunicating segment of the posterior cerebral artery (P1 hypoplasia) (p = 0.02) independently and negatively correlated with stump pressure. Both contralateral A1 hypoplasia (OR 26.25, 95% CI 4.52-152.51) and ipsilateral P1 hypoplasia (OR 8.75, 95% CI 1.83-41.94) were independently related to the TNSSEP changes. However, only ipsilateral P1 hypoplasia (OR 8.76, 95% CI 1.61-47.67) was independently related to MNSSEP changes. TNSSEP monitoring appears to be superior to MNSSEP in detecting CC-related hypoperfusion. Correlation with stump pressure and SSEP changes indicates that TNSSEP, and not MNSSEP monitoring, is a reliable indicator of cerebral ischemia in the territory of the anterior cerebral artery.

Eleven Year's Single Center Experience of Endovascular Treatment of Anterior Communicating Artery Aneurysms: Focused on Digital Subtraction Angiography Follow-Up Results.

ObjectiveAnterior communicating artery (AcomA) aneurysms represent the most common intracranial aneurysms and challenging to treat due to complex vascularity. The purpose of this study was to report our experience of endovascular treatment of AcomA aneurysms.MethodsBetween January 2003 and December 2013, we retrospectively reviewed the medical records of 134 AcomA aneurysm patients available more than 6 months conventional angiographic and clinical follow-up results. We focused on aneurismal or AcomA vascular characters, angiographic and clinical follow-up results, and retreatment.ResultsThe rate of ruptured cases was 75.4%, and the small (<10 mm) aneurysms were 96.3%. Based on the subtypes defined by dominance of A1, 79 patients (59%) had contralateral A1 hypoplasia or agenesis. The immediate post-procedural angiography confirmed complete occlusion in 75.4%, partial occlusion in 24.6%. Procedure related complications were observed in 25 (18.6%) patients. Most of the adverse events were asymptomatic. Follow-up conventional angiography at ≥6 months was performed in all patients (mean 16.3 months) and major recanalization was noted in 6.7% and regrowth in one case. The aneurysm size (p=0.016), and initial treatment results (p=0.00) were statistically significant risk factors related to aneurysm recurrence. An overall improvement in mRS was observed during the clinical follow-up period and no rebleeding episode occurred.ConclusionThis study demonstrated that endovascular treatment is an effective treatment modality for AcomA aneurysms with low morbidity. Patients should take long term clinical and angiographic follow-up in order to assess the recurrence and warrant retreatment, especially ruptured, large, and initially incomplete occluded aneurysms.

A1 segment hypoplasia accompanied by AcomA aneurysms assessed with magnetic resonance angiography

This study is to evaluate the use of three-dimensional time-of-flight magnetic resonance angiography (3D-TOF MRA) at 3.0 T for the detection and classification of A1 segment hypoplasia based on a large case series and investigates the potential links with AcomA aneurysm occurrence. Between January 2009 and June 2012, 8,013 patients underwent MRA examination at 3.0 T in our hospital. MRA was performed using 3D-TOF with volume rendering technique. The presence and location of A1 segment hypoplasia and AcomA aneurysm was reviewed. Among the 8,013 patients examined, 138 patients were identified with AcomA aneurysms. 425 patients were defined with A1 segment hypoplasia, among whom 303 right-sided A1 hypoplasia and 122 left-sided A1 hypoplasia. 60 of these 425 patients were confirmed with AcomA aneurysms, among them were 49 right-sided A1 hypoplasia. The prevalence of AcomA aneurysm with A1 segment hypoplasia was 14.1 %, which was much higher compared with that (1.0 %) of AcomA aneurysm without A1 segment hypoplasia (P < 0.001). The incidence of right-sided A1 segment hypoplasia either accompanied with AcomA aneurysm or not was much greater than that of left-sided. Intracranial AcomA aneurysm development appeared to be associated with A1 segment hypoplasia.

Carotid siphon geometry and variants of the circle of Willis in the origin of carotid aneurysms

This study evaluated anatomical variants in the carotid siphon and of the circle of Willis in patients with aneurysms. We performed a retrospective analysis of cerebral angiographies. The Control Group was composed of patients without aneurysms. Posterior communicating artery (PcomA) aneurysms were more common in women (p<0.05), and the anterior communicating artery (AcomA) aneurysms in men (p<0.1). The incidence of fetal-type PcomA was higher in cases with co-occurring PcomA aneurysm (24 versus 8%, p<0.05). Patients with AcomA aneurysm had higher incidence of A1 hypoplasia (p<0.0001, OR=32.13, 95%CI 12.95-79.71) and lower frequency of fetal-type PcomA compared to their control counterparts (p=0.0125). The angle of carotid siphon was narrower in patients with PcomA aneurysm (27.3±19.1 versus 34.8±22.6, p=0.028). In conclusion, a narrower carotid siphon or the presence of fetal-type PcomA or A1 hypoplasia may cause hemodynamic stress, thereby promoting the formation of aneurysms in susceptible individuals.

Selection of Arterial Input Function for Postprocessing of Cerebral CT Perfusion in Chronic Unilateral High-grade Stenosis or Occlusion of the Carotid or Middle Cerebral Artery

We evaluated the effect of the arterial input function (AIF) on computed tomography perfusion (CTP) in patients with unilateral high-grade stenosis or occlusion in the carotid artery or middle cerebral artery without acute stroke. CTP datasets were retrospectively postprocessed using the same venous output function and different AIF selections: the second segment of the anterior cerebral artery (A2 AIF), the second segment of the middle cerebral artery (MCA) on the lesion side (affected M2 AIF), and M2 on the contralateral side (nonaffected M2 AIF). We measured CTP values in the region of interest (ROI) in the bilateral MCA territory and evaluated the lesion-to-contralateral ratios. The mean and standard deviations of cerebral blood flow (CBF) on the normal side were similar to previously reported data only when using "non-affected M2 AIF." Selecting an "affected M2 AIF" overestimated the CBF and shortened the mean transit time (MTT) in normal and lesion areas. Selecting an "A2 AIF" may cause overestimation of CBF in the normal side in patients with nonaffected-side A1 hypoplasia or occlusion. The sensitivity of the CBF ratio or MTT ratio to detect these unilateral cerebrovascular diseases was 100% using "nonaffected M2 AIF for bilateral MCA ROIs" and 70% (CBF ratio) and 90% (MTT ratio) using "respective AIF." The use of "nonaffected AIF for the bilateral MCA ROIs" was found to be the best of these AIF-ROI combinations in patients with chronic unilateral carotid or M1 severe stenosis or occlusion.

Anterior Cerebral Artery A1 Segment Hypoplasia May Contribute to A1 Hypoplasia Syndrome

Anterior cerebral artery A1 segment hypoplasia is an uncommon fetal variant of the circle of Willis. The frequency of this congenital variation is 1–13% as derived from angiograms and autopsy reports. Impaired collateral blood flow through the circle of Willis is a recognized risk factor for ischemic stroke. The A1 segment of the anterior cerebral artery is a principal supplier of anterior collateral blood flow. The aim of our study was to determine whether A1 segment hypoplasia may be responsible for acute ischemic stroke. We consecutively examined 280 acute ischemic stroke patients (aged 66.9 ± 14.2 years). Cerebral magnetic resonance angiography was performed within 72 h of ischemic stroke onset. The overall incidence of A1 variation in our experimental group was 15.0% (n = 42, agenesis/hypoplasia = 18/24), which was statistically higher than in the control group (n = 12). The majority (n = 30, 71.42%) had ipsilateral striatal lacunar infarctions. Based on our results, A1 agenesis/hypoplasia appears to be a risk factor contributing to ischemic stroke, especially to strokes in arteries penetrating the striatal area.

Surgery of Anterior Communicating Artery Aneurysms with Special Reference to Surgical Anatomy.

We experienced 367 anterior communicating artery aneurysms (ACOAA) in 360 patients out of 1088 cerebral aneurysms operated on during recent 14 years. Three hundred and thirty three cases presented with subarachnoid hemorrhage, while the other 27 cases with unruptured ACOAA were detected during angiography for other ruptured aneurysm or other disease.The most common direction of ACOAA was anterior (39%), followed by superior, inferior, and posterior. The size of ACOAA was less than 10 mm in 303 (82/6%), between 11 mm and 24 mm in 59 (16.1%), and giant type in 5 (1.3%). Intraoperatively we found abnormalities of anterior communicating artery (ACOA) complex frequently. The vascular anomalies of ACOA complex were classified into four categories : anomalies of the A1, the ACOA, the A2, and the recurrent artery of Heubner. In 360 cases of ACOAA, A1, anomaly was the most common. Hypoplasia of A1 was observed in 58 cases (16.1%), aplasia of A1 in 15 cases (4.2%), and fenestration of A1 in 2 cases (0.6%). Duplication of ACOCA was present in 8 cases (2.2%), triplication of ACOA in 2 cases (0.6%), and fenestration/ plexiform of AOCA in 25 cases (6.9%). Unpaired A2 was shown in 4 cases (1.1%), triplication of A2 in 9 cases (2.5%), and frontal branch from A, in 2 cases (0.6%). The only anomaly of recurrent artery of Heubner was duplication, which was present in 10 cases (2.8%).In conclusion, for the successful surgery of ACOAA, we must take these anomalies into consideration in planning the surgical strategy.

Angiographic evaluation of brain infarction limited to the anterior cerebral artery territory.

Brain infarction localized in the anterior cerebral artery territory is rather uncommon, and its etiology has not yet been fully elucidated. Based on computed tomographic findings, 17 patients with solitary anterior cerebral artery territory infarction were selected from among 3,619 patients admitted consecutively to our institute. Patients without angiographic examinations were excluded. The angiographic findings and clinical category of stroke were analyzed in each patient. Angiographic abnormalities were revealed in all patients. These consisted of occlusive changes (n = 10) or reversible segmental dilatation (n = 3) of the anterior cerebral artery, A1 hypoplasia (n = 5), and occlusive changes of the carotid artery (n = 3). In one patient with anterior cerebral artery occlusion, the occluded artery was reopened and subsequently became reoccluded. The clinical category of stroke was classified as atherothrombotic in 10 patients, cardioembolic in three, and undetermined in the remaining four. In eight of the 10 patients with atherothrombotic infarction, the anterior cerebral artery was narrowed or occluded. In all patients with cardioembolic infarction, the A1 segment contralateral to the infarction was hypoplastic. In our series, solitary anterior cerebral artery territory infarction was attributable most commonly to local atherothrombosis and occasionally to cardiogenic embolism. A hypoplastic A1 segment may facilitate the occurrence of embolism in the anterior cerebral artery. Reversible dilatatory and occlusive changes of this artery may be another important cause of infarction.