Angiographic classification of aneurysms of the horizontal segment of the anterior cerebral artery

Ten aneurysms of the horizontal portion of the anterior cerebral artery (A1) were analyzed. These 10 aneurysms were classified into three types according to the mode of the origin of the neck of the aneurysm from the A1 segment: (a) an aneurysm originating from the junction of the A1 segment and the lenticulostriate artery, (b) one from the proximal end of the fenestration of the A1, and (c) one from the top of the A1 loop (elongation and kinking of the A1 segment). In these aneurysms, their size, the side of the A1 segment with an aneurysm, the multiplicity of aneurysms, the coexistence of hypertension, the grade of the patients, the laterality of the subarachnoid blood clots (as seen on computed tomography scans) and surgical outcome were analyzed.     

Distal anterior cerebral artery mirror aneurysms and middle cerebral artery aneurysms

A 52-year-old woman presented with bilateral distal anterior cerebral artery (ACA) mirror aneurysms, in addition to two right middle cerebral artery (MCA) aneurysms. The left distal ACA and right MCA aneurysms were clipped through right interhemispheric and right pterional craniotomies. The right distal ACA aneurysm was thrombosed. Distal ACA aneurysms tend to be multiple, but mirror aneurysms are rare, especially in the absence of congenital vascular anomaly. Single stage unilateral craniotomy is recommended for surgical treatment.     

Surgical treatment of distal anterior cerebral artery aneurysms with horizontal head position.

OBJECTIVE: In the surgery for a distal anterior cerebral aneurysm which is applied with a vertical head position, the dome of the aneurysm makes it difficult the expose the neck and the proximal artery. This study was performed to evaluate the applicability of the alternative contralateral interhemispheric approach with a horizontal head position for clipping these aneurysms. METHOD: The head of the patient was placed in the horizontal position such that the aneurysm side remained at the top and then tilted 45 degrees superiorly. On the contralateral side, the craniotomy, interhemispheric dissection and clipping were performed in 12 patients with 13 aneurysms. RESULTS: All aneurysms were clipped successfully. Problems in the standard supine position such as the obstruction of the access to the aneurysm neck and the proximal artery by the dome were not encountered. Vasospasm developed in 4 patients and akinetic mutism in 1 patient; postoperative convulsion due to an inadvertent cortical venous injury in one patient resolved with medical treatment. Hydrocephalus developed in 2 patients; one patient needed placement of a ventriculoperitoneal shunt while the other responded to occasional lumbar punctures. Mortality or permanent morbidity did not occur. CONCLUSION: The horizontal head position may be an alternative for circumventing difficulties posed by the location of distal anterior cerebral artery aneurysms.     

Saccular aneurysms of the distal anterior cerebral artery

We report a series of 42 consecutive patients with aneurysms of the distal anterior cerebral artery (ACA). Of these, 36 patients had one aneurysm, 5 had two aneurysms, and one had three aneurysms. Thirty patients had a ruptured distal ACA aneurysm; among these patients, the size of the aneurysm was less than 5 mm in diameter in 20, 6 to 10 mm in 7, and larger than 11 mm in 3. Eighteen patients (42.9%) had multiple aneurysms, and distal ACA aneurysms were responsible for a subarachnoid hemorrhage in 10. Thirty-four patients underwent direct surgery, and 30 of these had excellent outcomes 3 months after surgery. The treatment of patients with distal ACA aneurysms is often technically difficult, because of their broad neck configuration and the coexistence of other aneurysms. Nevertheless, the present study emphasizes that distal ACA aneurysms tend to bleed, irrespective of their size, and that excellent outcomes are obtainable by direct surgery.     

Giant aneurysms of the horizontal segment of the anterior cerebral artery: report of two cases

Two cases of giant aneurysm of the horizontal segment of the anterior cerebral artery (A1) are presented. The rare occurrence of a giant aneurysm in this location necessitates evaluation of the cross-flow through the anterior communicating artery when planning surgical strategy. On the basis of angiographic findings, trapping of the A1 on both sides of the aneurysm neck was performed in Case 1, and aneurysmorrhaphy utilizing an angioplastic multiple-clipping method of A1 endarterectomy was accomplished in Case 2. The postoperative courses of both patients were satisfactory.     

Ruptured anterior communicating artery aneurysms associated with fenestration of the anterior cerebral artery

Two patients with ruptured anterior communicating artery aneurysms associated with fenestration of the anterior cerebral artery are reported. In the literature, only 12 angiographic demonstrations of fenestration of the anterior cerebral artery have been reported. All fenestrations were limited to the distal half of the A1 portion, and seven of the 12 cases were associated with aneurysms. The high incidence of coexisting fenestration and aneurysm suggests that congenital factors may play a role in the pathogenesis of cerebral aneurysm.     

Surgery for unruptured anterior cerebral artery aneurysms

In Japan, a large number of surgical treatments for unruptured intracranial aneurysms have been performed. On the other hands, it is known that surgical treatment for unruptured intracranial aneurysms is the most frequent source of lawsuits in the neurosurgical field. Neurosurgeons have the duty to disclose all risks and consequences of a proposed surgical procedure to each patient. Moreover, precise knowledge of surgical risks would be helpful in preventing complications from occurring. However, it is almost impossible that a single surgeon or an institute have experiences with all possible surgical complications because there is limitation of the number of surgery. In this review series, we attempted an exhaustive bibliographic survey of the possible surgical complications including exceptional ones, and then, determined the frequency of each complications as far as possible quantitatively. In this paper, we focused on the complications of surgical treatment for anterior cerebral artery aneurysms.     

大脑前动脉近端动脉瘤的显微外科治疗

目的探讨大脑前动脉近端动脉瘤(A1动脉瘤)的临床特征及外科手术技巧。方法1995年6月～2003年12月间共治疗颅内动脉瘤患者362例,其中A1动脉瘤占2．2％(8例),对A1动脉瘤患者的临床资料进行回顾性分析。结果所有动脉瘤均位于A1穿动脉的起始部,起源于内侧远端纹状体动脉的3例,内侧近端纹状体动脉的5例。术中发现后方指向的6例,下方指向的2例。8个动脉瘤均为囊性动脉瘤,其中6例为小动脉瘤,平均直径6．9mm。全组动脉瘤经手术夹闭,患者预后优7例,良1例。结论手术治疗A1动脉瘤保护A1穿动脉和选用合适的瘤夹是预防缺血性并发症的关键。     

Long-term outcome following anterior cerebral artery ligation for ruptured anterior communicating artery aneurysms

The long-term prognosis (15 years) was determined for 17 patients who had undergone anterior cerebral artery (ACA) ligation as the sole treatment for an anterior communicating artery aneurysm. The number of early and late rebleeds was lower than expected from previously ruptured aneurysms. Late ischemia was not a major complication while late postoperative epilepsy occurred in 19% of survivors. In a review of previously published series, ACA ligation appears to have significantly reduced the rates of both early and late rebleeding. This study helps to define the late results of "conservative" operations for ruptured aneurysms.     

Dissecting aneurysms of the anterior cerebral artery and accessory middle cerebral artery. Case report

A 66-year-old woman presented with dissecting aneurysms of the anterior cerebral artery (ACA) and accessory middle cerebral artery (MCA) manifesting as subarachnoid hemorrhage but without radiological evidence of the dissecting aneurysms. Intraoperative observation revealed that the vessel walls were dark purple in color, a typical finding of dissecting aneurysm. The abnormal A1 segment was trapped and the dissecting aneurysm of the accessory MCA was wrapped. In the case of SAH of unknown origin, dissecting aneurysm should always be kept in mind even if the angiogram does not show any abnormal finding. This is the first reported case of dissecting aneurysm of the accessory MCA.     

Distal anterior cerebral artery aneurysms: bifrontal basal anterior interhemispheric approach

BACKGROUND: Distal anterior cerebral artery (DACA) aneurysms are uncommon. Most authors have reported technical difficulties during surgery for these aneurysms, and a variety of surgical approaches have been advocated. METHODS: Over a period of 5 years (1999-2003), 67 patients with DACA aneurysms were operated. Twenty-eight of these were operated on through the bifrontal basal anterior interhemispheric approach. Of the 28 patients, 68% were in poor clinical grade (Hunt and Hess grade III-V) and 89.3% had a Fisher grade III and IV on computed tomography scan. A surgical trajectory about 2 to 3 cm superior to the anterior cranial fossa floor led directly to the aneurysm. Proximal control was achieved before aneurysm dissection and parallel clipping. RESULTS: Good outcome (Glasgow Outcome Scale V and IV) was seen in 57.19 of the patients, 14.3% had a poor outcome, and 28.6% died. The cause of death in most patients was found to be a poor clinical grade, postoperative infarct, or presence of multiple aneurysms. CONCLUSIONS: The advantages of the bifrontal basal anterior interhemispheric approach were the following: (a) It provided the shortest and a direct trajectory to the aneurysm. (b) Proximal control of the parent A(2) vessels could be easily achieved. (c) Release of cerebrospinal fluid from basal cisterns could be done, if necessary. (d) There was a minimal distortion of or traction over the aneurysm.     

Paraparesis associated with ruptured anterior cerebral artery territory aneurysms

BACKGROUND: Paraparesis is a rare but characteristic manifestation of ruptured anterior communicating artery or anterior cerebral artery (ACA) aneurysms, but the pathogenesis remains unclear. This study investigated the neuroimaging and clinical features of patients with such paraparesis to evaluate possible causes. METHODS: Nine of 178 patients with ruptured anterior communicating artery or ACA aneurysms presented with paraparesis among 462 patients with subarachnoid hemorrhage (SAH) admitted between May 1996 and November 2001. Diffusion-weighted magnetic resonance (MR) imaging was performed within 48 hours of the onset of SAH in 4 of these 9 patients. The clinical course and neuroimaging studies of these 4 patients were retrospectively reviewed. RESULTS: Diffusion-weighted MR imaging revealed -intensity areas in the medial aspects of the bilateral frontal lobes, which were supplied by the ACAs and distal to the aneurysms, in all 4 patients. These high-intensity lesions had normal to subnormal values of apparent diffusion coefficient (ADC). Most of the high-intensity lesions recovered and did not result in the final lesions regardless of the ADC values, but some lesions with subnormal ADC values resulted in cerebral infarction. Paraparesis was transient and almost completely resolved in 3 patients. CONCLUSIONS: Diffusion-weighted MR imaging detected primary brain damage in the ACA territories caused by acute SAH, which was compatible with the clinical paraparesis. Primary brain damage caused by SAH may include 3 types of lesions: reversible with normal ADC value, reversible with subnormal ADC value, and irreversible with subnormal ADC value.     

Distal anterior cerebral artery aneurysms: a clinical series

Thirty patients with distal anterior cerebral artery (DACA) aneurysms were seen at the Royal Adelaide Hospital in the period 1970-1996. There were seven males (23%) and twenty three females (77%) with a mean age of 50 years. The average follow up was 5 years. Multiple aneurysms were present in seven cases (23%). The mean size of aneurysms was 5 mm. There were two post-traumatic aneurysms and one mycotic aneurysm. Out of the 30 cases, 19 presented with subarachnoid haemorrhage from ruptured DACA aneurysms. Eight (42%) of them were in good clinical grade (I or II). Operations were carried out in 25 (83%) patients. All five cases with unruptured aneurysms and the eight patients with good clinical grade had good recovery. In contrast, only six (55%) out of 11 patients with poor clinical grade had good outcome. The overall management mortality for the 19 cases with ruptured aneurysms was 16%. Postoperative complication occurred in two cases (8%), one patient developed deep vein thrombosis and seizures, the other patient had transient upper limb weakness. Although there is a definite trend towards better management outcome in the published series of DACA aneurysms over the years, there is still significant mortality and morbidity in the poor grade patients. Early surgery will prevent the deaths from rebleeding and may allow optimal management of vasospasm.