Outcome in 43 Patients With Distal Anterior Cerebral Artery Aneurysms
Background and Purpose The aim of this retrospective multicenter study was to evaluate the outcome of distal anterior cerebral artery (DACA) aneurysms and to determine the incidence, causes, and consequences of unfavorable outcomes.
Methods 43 patients with 50 DACA aneurysms (27 females and 16 males, mean age 49 years) were studied retrospectively. Forty-four DACA aneurysms were treated surgically (83% with an interhemispheric approach), and 2 were embolized. At postoperative day 10, all patients underwent routine angiography. The outcome at 6 to 12 months was scored according to the Glasgow Outcome Scale (GOS).
Results 35 DACA aneurysms were ruptured. Among the 26 “good”-grade patients (Hunt and Hess grades I through III), 18 (69.2%) were in GOS 1, 2 in GOS 2 (7.7%), 2 in GOS 3 (7.7%), and 4 in GOS 5 (15.4%); among the 9 “poor”-grade patients (Hunt and Hess grades IV and V), 1 (11.1%) was in GOS 1, 2 in GOS 2 (22.2%), 2 in GOS 3 (22.2%), and 4 in GOS 5 (44.5%). The initial intracerebral hemorrhage (ICH) (40%) induced neurological aftereffects in 8 patients. An operative rupture occurred in 40%, with a temporary occlusion in 28.6% that was responsible for mediocre results in 3 patients (8.7%). A postoperative thrombosis was observed in 4 patients (11.4%) and an aneurysmal remnant in 1 (2.8%). Ten DACA unruptured aneurysms were clipped without operative rupture or thrombosis.
Conclusions The authors suggest that the proportion of ruptured DACA aneurysms evolving to a GOS 1 or 2 was similar to that of aneurysms found in other locations, after early surgery. Endovascular treatment should be considered in the management of uncommon ruptured fusiform DACA aneurysms.
The distal segment of the anterior cerebral artery is defined as the distal portion to the anterior communicating artery. DACA aneurysms, whose low incidence ranged from 2.1 to 9.2%, include aneurysms of the pericallosal and calloso-marginal arteries.1 2 In most cases this type of aneurysm distant to the circle of Willis has clinical characteristics that present technical difficulties when treatment is by neck clipping. It is considered to have a poorer prognosis than that of aneurysms in other locations.3 4 5 Recent series6 7 8 9 have concluded that the prognosis of DACA aneurysms was in fact similar to those observed in the other locations. A poor outcome was related mainly to a poor preoperative condition. However, no recent studies have reported their results after a routine follow-up postoperative angiography.
The aim of the present study, carried out in a series of 43 patients with DACA aneurysms, was to evaluate follow-up and determine the main causes and the consequences of unfavorable outcomes.
Subjects and Methods
Population and Aneurysms
DACA aneurysm were diagnosed in 43 patients (5.7%) selected from a group of 750 patients treated for cerebral aneurysms in two departments of neurosurgery (university hospitals in Amiens and Rouen) since July 1986 (Table 1⇓). There were 27 females and 16 males (sex ratio, 1.7:1), ranging in age from 17 to 77 years (mean age, 49 years). The DACA aneurysms were ruptured in 35 patients (cases 1 through 35), and their preoperative clinical status was graded according to the Hunt and Hess scale.10 A single DACA aneurysm was present in 23 patients (cases 1 through 23). The other 12 patients (cases 24 through 35) exhibited multiple aneurysms, located on the DACA in 7 patients, on the MCA in 3, and on the ICA in 2. Incidental DACA aneurysms were discovered in 8 patients (cases 36 through 43), without SAH in 2 and after aneurysmal rupture of the ACoA in 4 and the ICA in 2.
The 50 DACA aneurysms were located in four sites. Four aneurysms (8%) were located in proximity to the ACoA, 7 (14%) at the origin of the frontopolar artery, 36 (72%) at the pericallosal bifurcation (between calloso-marginal and pericallosal arteries), and 3 (6%) distal on the DACA. Forty-five DACA aneurysms (90%) were saccular, and 5 (10%) were fusiform. The fusiform aneurysms were bilateral on dysplastic arteries in 2 patients (cases 27 and 30) and unilateral in 1 (case 3).
Patients were managed according to a standard policy that included the following: comprehensive intensive care; intracranial pressure monitoring; ventricular derivation; surgery within 48 hours after admission; aggressive prevention and management of vasospasm, including administration of nimodipine; postoperative hypervolemia; and transcranial Doppler evaluation.
Standard microvascular techniques and magnifications were used in all cases to obliterate the aneurysm. Forty-four DACA aneurysms were treated surgically. The approach was pterional, with use of a frontotemporal craniotomy for the DACA aneurysms located either in proximity to the ACoA (n=4) or at the origin of the frontopolar artery (n=2). The craniotomy was enlarged (n=1) in treating one ruptured aneurysm of the ACoA and one associated DACA. These aneurysms required a dissection in the midline and an extensive gyrus rectus resection. For more distal DACA aneurysms, the approach was interhemispheric, with use of a frontal parasagittal craniotomy homolateral to the parent vessel (n=32). The dura was opened to the midline, with care taken not to damage the bridge veins. The interhemispheric fissure was opened by passing along the side of the homolateral falx to the parent DACA. A gentle retraction was applied on the self-retaining retractor to open the interhemispheric fissure. Under optic magnification, the clots in the cistern were removed to expose the corpus callosum and the two DACA. The homolateral or mirror DACA-associated aneurysms to the ruptured DACA were treated by the same surgical procedure (n=5). Endovascular treatment was performed on 1 ruptured (case 3) and one unruptured (case 37) DACA aneurysm.
During the immediate postoperative period, the patients were evaluated clinically every hour, then each day. A routine CT scan and routine angiography were performed on days 10 to 12 after surgery. These routine examinations were performed immediately in cases of early postoperative neurological degradation. The neurological outcome was scored according to the GOS in a follow-up period ranging from 6 to 12 months after surgery11 (Table 2⇓). The causes of unfavorable outcome (GOS≥2) were defined according to the criteria previously described.12 Briefly, the ICH was incriminated when the size and location of hypodensity on the CT scan corresponded to the previous ICH. Thrombosis of a parent vessel was observed in an area of low density consistent with infarction in the distribution of the occluded DACA on the control CT scan and by a vascular occlusion beyond the clip in routine angiography.
Ruptured DACA Aneurysms
Among the 35 patients with ruptured DACA aneurysms, 2 (5.7%) were in Hunt and Hess grade I, 13 (37.1%) in grade II, 11 (31.4%) in grade III, 7 (20.1%) in grade IV, and 2 (5.7%) in grade V. The mean time of surgery after bleeding for the 26 “good”-grade patients was 8 days, with 78% of patients operated on before the fourth day. Among the 26 good-grade patients (grades I to III), 18 (69.2%) were in GOS classification 1 and subsequently resumed normal activity, and 2 (7.7%) patients remained in GOS 2, 2 (7.7%) in GOS 3, and 4 (15.4%) in GOS 5. All 9 “poor”-grade patients (grades IV to V) presented a voluminous initial ICH. The mean time of surgery after bleeding for the 9 patients in the poor grade was 1.2 days. Only case 32 evolved favorably, with the patients resuming part-time work (GOS 1). The other 8 patients evolved to GOS 2 (cases 28 and 31), GOS 3 (cases 18, 20, 27, 30 and 32), and GOS 5 (case 19). In summary, 23 patients (65.7%) obtained good results (ie, GOS 1 and 2) and 12 mediocre results (GOS>2).
The initial ICH occurred in 14 patients (40%). The location of the ICH induced lesions in the corpus callosum, the dominant frontal lobe, and the centrum semiovale. This induced neurological aftereffects in 2 good-grade patients (cases 14 and 15) and 6 poor-grade patients (cases 22, 23, 31, 34, and 35), with mediocre results in 4 (11.4%). The other 4 patients were unable to return to normal activities (GOS 2). An initial intraventricular hemorrhage occurred in 6 patients (17.1%). Ventricular catheters were inserted into 1 good-grade and 5 poor-grade patients because of significant ventricular enlargement. A ventricular peritoneal shunt was required in 2 patients (5.7%).
The incidence of contusions related to the approach was 9.4%, without clinical consequences, and a normal CT scan was carried out at 6 months. A surgical aneurysmal rupture occurred in 14 patients (40%). In 10 patients (28.6%), this rupture obscured operative visibility and imposed a temporary vessel trapping. The temporary vessel trapping was responsible for mediocre results in 3 patients (8.7%). In cases 9, 19, and 25, a prolonged temporary vessel trapping (ie, an operative rupture of a aneurysmal dilatation of the pericallous bifurcation that was reconstructed) revealed an area of low density consistent with ischemia in the distribution of the temporarily occluded DACA on routine CT scan. The routine angiography showed permeable DACA. Postoperative thrombosis was confirmed in four patients (cases 21, 26, 27, and 30) with mediocre results (11.4%). One good-grade patient (case 26), a 62-year-old woman, was admitted with a small ICH. The initial angiography showed a double aneurysm of the left pericallosal artery. The operative rupture of the second aneurysm hindered the clip application. In the immediate postoperative period, the patient exhibited a syndrome of the left DACA, and control angiography confirmed the diagnosis of postoperative thrombosis. A 22-year-old man (case 21) had an aneurysm located at the low pericallosal bifurcation next to the ACoA, exposed by a pterional approach. The dissection of the aneurysmal sac was complicated and the operative rupture, caused by a neck fissuration, prompted a definitive occlusion of the internal frontal artery. The latter 2 patients, a 30-year-old man (case 27) and an 18-year-old woman (case 30), presented a bilateral fusiform aneurysm without neck that imposed a definitive occlusion of the pericallosal artery after operative rupture. In one patient (case 3), the fusiform DACA aneurysm was treated by an endovascular method that induced a definitive occlusion without neurological consequences. An aneurysmal remnant identified in 1 good-grade patient (2.8%) was complicated at postoperative day 18 after a rebleeding, which resulted in the death of the patient.
Management of Associated DACA Aneurysms
Ten unruptured DACA aneurysms were clipped. The DACA aneurysms associated with a ruptured DACA were treated by the same surgical procedure in cases 21, 23, 26, 28, and 32. The DACA aneurysms associated with a ruptured ICA or CoA, except case 38, were treated in a second procedure 1 month later (cases 36 and 39). Two asymptomatic aneurysms were treated surgically (cases 33 and 34). The use of clip applications produced neither operative rupture nor thrombosis. One unruptured distal DACA aneurysm was embolized without morbidity. Four associated DACA aneurysms were not treated because of a severe morbid status secondary to the ruptured aneurysm (n=3) or the patient’s refusal of treat ment (n=1).
The present retrospective multicenter study describes our experience in the treatment of 35 patients who had ruptured DACA aneurysms. Good results were obtained in 65.7% of our cases. The poor results were attributable to initial bleeding in 11.4%, thrombosis in 11.4%, temporary vessel trapping in 8.7%, and rebleeding in 2.8%. The surgical treatment of associated DACA aneurysms did not produce any complications.
A review of the literature over the past 10 years showed that the proportion of good postoperative results varied from 65% to 94.1% (Table 3⇓), and the mediocre results in these studies were essentially the result of the initial bleeding. In our series, we obtained good results in 65.7% of patients after an early surgery. It is probable that the series of pericallosal aneurysms are not comparable because of random selection: the extent of initial bleeding may influence the choice of management, and the timing of surgery is rarely indicated. Only Sindou et al8 reported a surgical timing at day 25 after hemorrhage. In our series, the mean time of surgery was day 8 after hemorrhage, because of the delayed hospital admission. In several reported series6 7 9 14 with more 30 cases of pericallosal aneurysms, the percentage of poor grade patients varied from 3.7% to 7.2%, which in fact was lower than the 25.7% obtained in our series or in studies reported by other authors.8 13 15 The poor preoperative status is a factor in poor outcome but not an argument in favor of delaying surgery.16 Indeed, in our series 33.3% of the poor grade patients experienced good results after early surgery (day 1.2 after SAH).
Furthermore in the literature, the incidence of ICH associated with ruptured DACA aneurysms varied from 40% to 73%.6 7 8 13 20 This frequency was clearly higher than 17.1% for the aneurysms found in various locations.21 This high frequency is probably secondary to the confined pericallosal subarachnoid space.22 23 The ICHs secondary to a rupture of the DACA aneurysm were located in the callosum corpus. They rise into two separate areas of a butterfly-like hematoma within the frontal lobes on CT scan with neurological consequences.24 For Hernesniemi et al,6 mortality was related to severe bleeding with ICH (9 of 54 operated DACA aneurysms). For Wisoff and Flamm,9 all 4 patients in preoperative IV grade with an ICH had a poor outcome. For the other authors,8 20 25 the presence of an ICH did not hinder a good outcome. In our series, among the 14 patients with ICH, 6 evolved to a GOS 1 or 2. Two arguments suggest early surgery for the DACA with an ICH: first, intracranial hypertension requires emergency management; second, the functional prognosis of an ICH remains unpredictable.
Also reported were the incidence, causes, and consequences of surgical complications in patients undergoing repair of ruptured DACA, which remains poorly understood. The surgically ruptured aneurysms varied in these reports from 0% to 50%,1 6 7 8 9 13 20 26 taking into consideration that over a period of 20 years microsurgical conditions have advanced considerably. This significant variation in results can be explained by the basic definition of operative rupture. The consequence of a temporary trapping are not negligible. The study of Hernesniemi et al6 reported that 19% of patients had complications caused by surgical rupture, which in 1 patient resulted in death. In our series, we noted an ischemic deficit with permeable vessel revealed on angiography in 3 patients. In these 3 cases the temporary trapping was a lifesaving procedure that was overprolonged. In the reported series, a routine angiogram was not performed, and the true incidence of inadvertent vessel occlusion remains unknown. Occlusion of a major vessel was identified in 2% to 26%.1 2 6 7 8 9 13 20 26 The impact of this occlusion was extremely variable. Among the 9 cases reported, 7 patients experienced a good outcome. In our series, after systematic control angiography we observed an 11.4% incidence of thrombosis. The occluded vessel was the distal pericallosal segment in 3 patients and a callosomarginal artery in 1. The thrombosis was responsible for a poor outcome in only 1 patient. In the other 3 patients, because the thrombosis was associated with an ICH it was difficult to determine the precise cause of poor outcome. The tendency of rebleeding is commonly high in this location, as demonstrated by a well-known cooperative study on intracranial aneurysms.27 Sindou and colleagues8 reported a 16% rebleeding rate in their series. This is therefore a major argument in favor of early surgery, which was performed whatever the patient’s preoperative clinical status. In our series, 1 patient (case 9) presented with rebleeding from an aneurysm remnant discovered on routine angiogram at postoperative day 18.
It is evident that the skill of the neurosurgeon is a major factor in DACA aneurysm surgery. In our series, surgery was performed by confirmed senior neurosurgeons; the operative difficulties and their consequences were due to this particular type of aneurysm. The frontal interhemispheric route is the approach used by all authors1 4 5 6 7 8 9 14 15 for DACA aneurysms located at the genu of the corpus callosum or supracallosal. Regarding the infracallosal aneurysms, the surgical approach still remains controversial. Ohno et al7 advocated a low-frontal interhemispheric approach, underlying the depth of the genu and the pial adherences of the cingulate giry. Other authors suggest clipping these infracallosal aneurysms via a pterional1 6 9 or bilateral subfrontal14 approach, maintaining that the dissection in the interhemispheric fissure provides an excellent exposure. We used a pterional approach for either the multiple aneurysm and aneurysms located near the ACoA or two aneurysms located at low frontopolar arteries. This approach permitted a good proximal parent vessel control and the exposure of the neck, thus avoiding a dissection of the fundus aneurysm. The frequent surgical rupture associated with the interhemispheric approach can be explained by the fact that the pericallosal aneurysm neck is exposed after the fundus, which was highly delicate procedure. The difficulties of the clip application may result from the small space of the pericallosal cistern with operative rupture, the ratio between the small diameter of the parent vessel and the broad base of these aneurysms, and the morphology of the sac. Indeed, the fusiform sac is difficult to treat surgically because of the absence of a neck. Dechaume et al4 suggested an aneurysm sac wrapping, and Geuna et al26 proposed that this aneurysm category was a contraindication to surgical treatment. In our series the 2 patients who were managed surgically had a poor outcome, with thrombosis of the parent vessel. The last patient (case 3) was treated by embolization. The proximal occlusion of the pericallosal artery did not induce functional consequences. In this fusiform morphology, the endovascular method may be considered the method of choice.
Finally, the proportion of ruptured DACA aneurysms evolving to a GOS 1 or 2 was similar to that of aneurysms found in other locations. The poor-grade patients should undergo early operation, because 33.3% in our study responded favorably. Control angiography was useful because the proportion of thrombosis and the risk of rebleeding in the case of aneurysmal remnant are not negligible. Furthermore, the uncommon fusiform DACA aneurysms, which bleed, should be treated using this endovascular method.
Selected Abbreviations and Acronyms
|ACoA||=||anterior communicating artery|
|DACA||=||distal anterior cerebral artery|
|GOS||=||Glasgow Outcome Scale|
|ICA||=||internal carotid artery|
|MCA||=||middle cerebral artery|
|TCD||=||transcranial Doppler ultrasonography|
We are grateful to Richard Medeiros for his advice in editing the manuscript.
- Received July 17, 1997.
- Revision received September 15, 1997.
- Accepted September 15, 1997.
- Copyright © 1997 by American Heart Association
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