Aneurysm of the posterior cerebral artery: report of eleven cases--surgical approaches and procedures

Partially thrombosed distal posterior cerebral artery aneurysm treated with surgical trapping through occipital transtentorial approach assisted by endovascular coil embolization

Background

Posterior cerebral artery (PCA) aneurysms are relatively rare. PCA aneurysms tend to be large, giant, fusiform, and partially thrombosed. Surgical treatments, such as neck clipping and trapping with or without bypass surgery, are curative treatments for thrombosed intracranial aneurysms. Few cases of surgical treatment of distal PCA aneurysms have been reported. We treated a partially thrombosed distal PCA aneurysm by trapping through the occipital transtentorial approach (OTA) assisted by endovascular coil embolization.

Case Description

A 21-year-old woman presented with a sudden headache. Brain computed tomography, magnetic resonance imaging, and a cerebral angiogram revealed a partially thrombosed aneurysm in the left PCA P3 segment. Her headaches had improved once within several days, but reoccurred due to an enlarged thrombosed aneurysm. Endovascular coil embolization was performed to assist the surgery. The aneurysm and the distal artery of the aneurysm were embolized to interrupt the blood flow into the aneurysm. The following day, trapping of the aneurysm was performed through the OTA. Eventually, we performed aneurysm excision because trapping alone was considered to have the potential for regrowth of the aneurysm. The patient's postoperative course was uneventful. No recurrence of the aneurysm was observed at the 2-year follow-up.

Conclusion

OTA could be useful for the treatment of distal PCA aneurysms, whereas coil embolization may support the surgical treatment of partially thrombosed intracranial aneurysms.

Distal Posterior Cerebral Artery Ruptured Aneurysm: A Rare Case Report and Review of Literature

Distal posterior cerebral artery aneurysms consist of a rare vascular entity whose treatment approach remains challenging. Few studies exist scarcely in the literature reporting cases of P4 ruptured aneurysms. In this study, we present the case of a 49-year-old female patient who was admitted to our Neurosurgery Department with the World Federation of Neurological Surgeons grade IV, Fischer grade IV subarachnoid hemorrhage due to a right distal posterior cerebral artery aneurysm. She successfully underwent surgery via a posterior occipital interhemispheric approach. The patient recovered well from surgery, and the following days, she was successfully extubated and had a significant neurological improvement. However, she died during her rehabilitation due to sepsis and severe acute respiratory distress syndrome.

Superficial Temporal Artery (STA)-Posterior Cerebral Artery (PCA) Bypass through Zygomatic Anterior Temporal Approach for Complex PCA Aneurysm: Technique Notes

BACKGROUND

Posterior cerebral artery (PCA) aneurysms are rare and the majority are giant, dissecting, or fusiform in morphology. Proximal occlusion of PCA without revascularization causes a high risk of ischemic complications. This study aimed to evaluate the safety and validity of using superficial temporal artery (STA)-posterior cerebral artery (PCA) Bypass through zygomatic anterior temporal approach in complex PCA aneurysms.

METHODS

Trapping or resecting of the aneurysms and reconstruction of the distal PCA through a zygomatic anterior temporal approach were performed in 6 patients from June 2017 to August 2020. Postoperative angiography was used to confirm the obliteration of the aneurysms and the patency of bypass artery. Neurologic function was assessed by the modified Rankin Scale.

RESULTS

Four male and 2 female patients with a mean age of 43.8 years (Range, 21-58 years) were assessed. Subarachnoid hemorrhage occurred in 5 patients, including 3 patients with Hunt-Hess grade IV, 2 patients with grade III, and 1 patient with grade I. All PCA aneurysms were treated with trapping or resecting of the aneurysms and revascularization of the distal PCA. Postoperatively, all aneurysms were eliminated and no new permanent neurological deficit was found. During the follow-up, Modified mRS of all patients were improved: There were 2 patients with mRS Score 0, 1 patient with mRS Score 1, 1 patient with mRS Score 3, and 2 patients with mRS Score 4. The long-term graft patency rate was 100%.

CONCLUSION

The STA-PCA bypass appears to be a safe and effective method for the treatment of complex PCA aneurysms requiring supplementing the blood flow in the area of the PCA. We established a surgical route, allowing the procedure to be done through the zygomatic anterior temporal approach. This approach provides adequate operative field exposure and reduces retraction of the temporal lobe.

Endovascular treatment of P3 segment of posterior cerebral artery aneurysm with stent and coils

Posterior cerebral artery (PCA) aneurysms are rare and usually arise from proximal portion of the artery. The distal location is even less frequent, and aneurysms in this location tend to be larger and dissecting. Although they can be treated by direct surgery, recently endovascular procedures have been preferred in some centers. We report a case of large aneurysm of the posterior cerebral artery in a 45-year-old female presenting with headache. An uneventful endovascular treatment was performed with stent and platinum coils achieving total occlusion of the aneurysm, and the patient had good recovery. The findings are compared to earlier reports and literature regarding the issue is discussed.

ENDOVASCULAR MANAGEMENT OF INTRACRANIAL ANEURYSMS ON DISTAL ARTERIAL BRANCHES: ILLUSTRATIVE CASE SERIES AND LITERATURE RETROSPECTION

Intracranial aneurysms located on distal arterial branches are sporadic and scarce. They account for 2%-7% of the middle cerebral artery and 0.7%-2.3% of the posterior cerebral artery aneurysms, where they mainly arise distally from the P2-related sites. Such aneurysms usually remain asymptomatic prior to rupture, making their diagnosis and management really demanding. Endovascular treatment comprising of different neurointerventional techniques is becoming the most operational up-to-date routine to approach distal cerebral branch aneurysms. In this single-institution case series, endovascular selective coiling and/or parent vessel occlusion resulted in successful and total aneurysmal exclusion from cerebral circulation, which brought good recovery. Hereby, we present an illustrative case series of distal arterial branch intracranial aneurysms, discussing their possible etiology and various endovascular management modalities. We also provide a literature retrospection concerned with this rare entity. In conclusion, due to their predisposition for rupture, distal branch intracranial aneurysms should be treated early and aggressively. We do believe that endovascular selective coil occlusion is the management method of choice, while parent vessel occlusion (with liquid embolics) is optimal when aneurysmal coiling cannot be achieved, or when distal cortical territory is well vascularized by strong collateral cerebral circulation.

How I do it: lateral supra-cerebellar infra-tentorial approach for P2-P3 junction cerebral aneurysms

BACKGROUND

P2-P3 junction aneurysms are challenging to treat surgically because of their frequent complex morphology and their location deep in close proximity to the midbrain. The sub-temporal route requires significant retraction of the temporal lobe in addition to potential injury to the vein of Labbe. We describe the technique for treating such aneurysms via a lateral supra-cerebellar infra-tentorial (LSCIT) approach, which eliminates manipulation of the temporal lobe.

METHOD

Cadaveric dissection provided comprehensive understanding of relevant anatomy. Intraoperative video shows clipping of the aneurysm using a LSCIT approach.

CONCLUSION

LSCIT approach allows safe clipping of P2-P3 aneurysms with minimal brain manipulation.

Endovascular Treatment of Posterior Cerebral Artery Aneurysms With Flow Diversion: Case Series and Systematic Review

BACKGROUND

Flow diversion of posterior cerebral artery (PCA) aneurysms has not been widely reported, possibly owing to concerns regarding parent vessel size and branch vessel coverage.

OBJECTIVE

To examine the safety and effectiveness of PCA aneurysm flow diverter treatment.

METHODS

Retrospective review of PCA aneurysms treated with the Pipeline Embolization Device (PED; Medtronic Inc, Dublin, Ireland) at 3 neurovascular centers, including periprocedural complications and clinical and angiographic outcomes. Systematic review of the literature identified published reports of PCA aneurysms treated with flow diversion. Rates of aneurysm occlusion and complications were calculated, and outcomes of saccular and fusiform aneurysm treatments were compared.

RESULTS

Ten PCA aneurysms in 9 patients were treated with the PED. There were 2 intraprocedural thromboembolic events (20%), including 1 symptomatic infarction and 1 delayed PED thrombosis. Eight of 10 patients returned to or improved from their baseline functional status. Complete aneurysm occlusion with parent vessel preservation was achieved in 75% (6/8) of cases at mean follow-up of 16.7 mo. Eleven of 12 (92%) major branch vessels covered by a PED remained patent. Including the present study, systematic review of 15 studies found a complete aneurysm occlusion rate of 88% (30/34) and complication rate of 26% (10/38), including 5 symptomatic ischemic strokes (13%; 5/38). Fusiform aneurysms more frequently completely occluded compared with saccular aneurysms (100% vs 70%; P = .03) but were associated with a higher complication rate (43% vs 9%; P = .06).

CONCLUSION

The safety and effectiveness profile of flow diverter treatment of PCA aneurysms may be acceptable in select cases.

Serpentine aneurysm of the posterior cerebral artery treated by internal maxillary artery bypass followed by parent artery occlusion: a case report and literature review

Serpentine aneurysms of the posterior cerebral artery (PCA) treated by the internal maxillary artery (IMA) bypass are rare. Here, the authors report the case of a 34-year-old male patient who presented with a half-year history of gradual severe headache and right-sided limb monoparesis and paresthesia lasting for 1 week. Preoperative angiograms showed a serpentine aneurysm in the left distal PCA, which was treated with internal maxillary artery-radial artery-posterior cerebral artery (IMA-RA-PCA) bypass followed by parent artery occlusion (PAO). The postoperative course was uneventful; radiological images revealed that the aneurysm disappeared, and there was good graft patency and excellent perfusion of the distal PCA territories. To the authors' knowledge, this is the first and only case of distal PCA serpentine aneurysm to be treated by IMA-RA-PCA bypass followed by proximal PAO. These findings suggest that IMA bypass surgery is a good and feasible treatment option for serpentine aneurysms of the PCA that can preserve the parent artery. Moreover, the anatomic segments of the PCA and different treatment options available for PCA serpentine aneurysms are also discussed in this study.

Posterior Cerebral Artery Reconstruction by In-Situ Bypass with Superior Cerebellar Artery via Occipital Transtentorial Approach

BACKGROUND

Posterior cerebral artery (PCA) aneurysms are relatively rare, and neck clipping is often difficult due to their fusiform shape. We report a case of a thrombosed aneurysm of the distal PCA for which curative trapping and parent artery reconstruction by in situ bypass were performed through an occipital transtentorial approach (OTA).

CASE DESCRIPTION

A 67-year-old woman had been suffering from numbness in the right face and limbs for 4 months. Radiologic imaging demonstrated a thrombosed aneurysm on a distal portion of the left PCA. Curative trapping of the aneurysm and in-situ bypass between the distal PCA and superior cerebellar artery were performed through the OTA. Before surgery, we had evaluated access to the PCA and feasibility of the bypass in a cadaveric simulation. The PCA was well exposed in the posterior half of the ambient cistern, and the proximity of the distal PCA to the superior cerebellar artery through a tentorial incision was confirmed.

CONCLUSIONS

This OTA could represent a useful option for definitive treatment of distal PCA aneurysms.

Characteristics and Endovascular Management of the Posterior Cerebral Artery Anterior Temporal Branch Aneurysms

PURPOSE

To investigate characteristics of the posterior cerebral artery anterior temporal branch aneurysm and the safety and efficacy of endovascular management.

MATERIALS AND METHODS

A total of 6 patients with anterior temporal branch aneurysms were enrolled. All 6 patients had concurrent occlusion of the ipsilateral anterior circulating arteries. The aneurysms ranged from 2.5 to 5.0 mm. All patients were treated and followed up.

RESULTS

Four unruptured aneurysms were treated with coil embolization of the aneurysm sac only, with the parent artery maintained in 2 patients, slow flow in the parent artery in one and thrombosis at the aneurysm neck leading to parent artery occlusion in the last one. One patient with subarachnoid hemorrhage was treated with coil embolization of both the aneurysm and the parent artery, and the last patient with subarachnoid hemorrhage was treated with the Glubran 2 glue to embolize both the aneurysm and the parent artery. One patient with subarachnoid hemorrhage died of lung complication after embolization. Followed up for 3 months to 1 year, the 4 patients with unruptured aneurysms had no symptoms, including 1 patient with slow flow in the anterior temporal artery and 1 patient with thrombosis and parent artery occlusion. The remaining patient with parent artery occlusion had a good recovery.

CONCLUSIONS

The anterior temporal artery aneurysm is a special subtype of aneurysm and can be readily misdiagnosed as on the posterior cerebral artery trunk or the superior cerebellar artery. Endovascular management has a greater success rate, good effect, and fewer complications but with greater difficulties.

Fetal-type posterior cerebral artery: the pitfall of parent artery occlusion for ruptured P2 segment and distal aneurysms

OBJECT

P2 segment and distal aneurysms are rare lesions of the cerebrovascular system. The efficacy and safety of endovascular occlusion for these types of aneurysms remain controversial. The aim of this study was to reveal risk factors for endovascular parent artery occlusion of ruptured P2 segment and distal aneurysms.

METHODS

Between March 2010 and November 2012, 812 patients with a ruptured intracranial aneurysm were admitted to the authors' hospital. Among them, 11 patients presented with P2 segment and distal posterior cerebral artery (PCA) aneurysms. These patients were subjected to endovascular treatment. Periprocedural data and clinical and angiographic records were studied retrospectively.

RESULTS

Of the patients with a ruptured PCA aneurysm, 2 of them underwent selective aneurismal coiling, and the remaining patients were treated with simultaneous occlusion of the parent artery. Patients with an adult-type PCA (n = 6), treated with either selective coiling or simultaneous parent artery occlusion, had no serious neurological deficits on follow-up. Four patients with a fetal-type PCA that was also occluded intraoperatively exhibited newly developed permanent paralysis and hemianopsia. However, 1 patient with a fetal-type PCA aneurysm that was selectively coiled recovered without complications. No recanalization was observed in any of the treated aneurysms.

CONCLUSIONS

Endovascular occlusion of an aneurysm and its parent artery is a safe and effective method for managing adult-type P2 segment and distal aneurysms. However, the authors' clinical data suggest that this method is of high risk for patients with fetal-type PCA aneurysms.

Treatment strategies for dissecting aneurysms of the posterior cerebral artery

BACKGROUND

Dissecting aneurysms of the posterior cerebral artery (PCA) are rare and difficult to treat because of their deep and unfamiliar locations and unusual shapes. Although several treatment modalities have been proposed, none have generated satisfying results. Our experiences with PCA-dissecting aneurysms are reviewed and the treatment strategies discussed.

METHODS

All consecutive patients with PCA-dissecting aneurysm who were treated in a tertiary referral hospital between January 1998 and March 2014 were identified by retrospective review. Their clinical characteristics, radiological findings, treatment modalities and outcomes were documented.

RESULTS

Of the 21 patients with 21 PCA-dissecting aneurysms, 9 had subarachnoid hemorrhage and 3 had acute infarction of the thalamus at presentation. The aneurysms involved P1 (n = 4), the P1-2 junction (n = 3), mid-P2 (n = 6), P2A (n = 3), P2P (n = 1) and the P2-3 junction (n = 4). The aneurysm shapes were as follows: fusiform (n = 12), partially thrombosed (n = 8) and blood blister-like aneurysms (n = 1). The mean size was 16.6 ± 9.7 mm. Parent artery occlusion (PAO) without bypass (n = 15), PAO with bypass (n = 2), stent-assisted endosaccular coiling (n = 3) and stent placement only (n = 1) were performed. All three patients who underwent stent-assisted endosaccular coiling and the single patient who underwent PAO without bypass developed aneurysm recurrence. Six of the ten patients who received a PAO without a balloon test occlusion (BTO) experienced PCA territory infarction, whereas only one of the five patients who received a PAO after passing the BTO experienced an infarction.

CONCLUSIONS

PAO for PCA-dissecting aneurysm was effective in preventing recurrence. In addition, BTO before PAO was helpful in identifying candidates who truly needed surgical revascularization.

Lateral supraorbital approach to ipsilateral PCA-P1 and ICA-PCoA aneurysms

Background:

Aneurysms of the posterior cerebral artery (PCA) are rare and often associated with anterior circulation aneurysms. The lateral supraorbital approach allows for a very fast and safe approach to the ipsilateral lesions Circle of Willis. A technical note on the successful clip occlusion of two aneurysms in the anterior and posterior Circle of Willis via this less invasive approach has not been published before. The objective of this technical note is to describe the simultaneous microsurgical clip occlusion of an ipsilateral PCA-P1 and an internal carotid artery - posterior communicating artery (ICA-PCoA) aneurysm via the lateral supraorbital approach.

Case Description:

The authors present a technical report of successful clip occlusions of ipsilateral located PCA-P1 and ICA-PCoA aneurysms. A 59-year-old female patient was diagnosed with a PCA-P1 and an ipsilateral ICA-PCoA aneurysm by computed tomography angiography (CTA) after an ischemic stroke secondary to a contralateral ICA dissection. The patient underwent microsurgical clipping after a lateral supraorbital craniotomy. The intraoperative indocyanine green (ICG) videoangiography and the postoperative CTA showed a complete occlusion of both aneurysms; the parent vessels (ICA and PCA) were patent. The patient presents postoperative no new neurologic deficit.

Conclusion:

The lateral supraorbital approach is suitable for the simultaneous microsurgical treatment of proximal anterior circulation and ipsilateral proximal PCA aneurysms. Compared to endovascular treatment, direct visual control of brainstem perforators is possible.

Endovascular parent artery occlusion of proximal posterior cerebral artery aneurysms: a report of two cases

We report two cases of proximal posterior cerebral artery (PCA) aneurysms treated with endovascular parent artery occlusion (PAO) with coils. In both cases, selective injection from the 4 F distal access catheter clearly showed the perforating arteries arising from the PCA. Case No 1, a 49-year-old woman, was successfully treated with preservation of a paramedian artery. Case No 2, a 54-year-old woman, was treated in the same manner. The patient underwent extensive thalamic infarction after the procedure because of paramedian artery occlusion. Endovascular PAO with coils is feasible for proximal PCA aneurysms; however, preservation of perforating arteries arising from the PCA is mandatory.

Aneurysms of the P2P Segment of Posterior Cerebral Artery: Case Report and Surgical Steps

The posterior cerebral artery (PCA) is divided into 4 segments: precommunicating segment (P1), postcommunicating segment (P2), quadrigeminal segment (P3), and calcarine segment (P4). Small aneurysms are more prevalent than large aneurysms in patients with ruptured aneurysms. P2 and P3 aneurysms are usually managed by the subtemporal approach. This is a case report of rupture saccular aneurysm of posterior cerebral artery on P2P segment. The authors show the surgical steps of these rare aneurysms with an illustrative case.

Endovascular treatment for aneurysms of the posterior cerebral artery: 12 years' experience with 21 cases

BACKGROUND AND PURPOSE

To discuss and summarize the strategies and complications of endovascular embolization for aneurysms of the posterior cerebral artery (PCA).

METHODS

Data of patients with PCA aneurysms treated by an endovascular procedure were analyzed retrospectively (n = 21). Twenty patients with aneurysms were treated by detachable coil embolization, and one patient was treated with n-butyl cyanoacrylate. Of the 21 aneurysm embolization cases, 9 were treated by parent artery occlusion (PAO), and 12 were treated by selective occlusion of the aneurysm (SOA).

RESULTS

All 12 aneurysms treated by SOA showed complete occlusion. Two aneurysms became recanalized 6 months after the first embolization and were then re-embolized; complete healing was observed on follow-up angiography. All patients showed acceptable outcomes without any procedural complications, except one patient who died 2 days after treatment. PAO resulted in 100% occlusion of all aneurysms. Cerebral infarction was noted in most patients (78%, n = 7). However, the area of infarction was small. Permanent neurological deficit was observed in two patients (22%), but their condition was not critical.

CONCLUSIONS

Aneurysm embolization with SOA is well indicated for saccular aneurysms with well-defined necks, whereas PAO carries a risk of ischemic complications. Although the PCA is rich in collateral circulation, ischemic complications were noted in most patients after PAO, and it was difficult to predict occurrence of these complications. However, the area of cerebral infarction tended to be small, and the neurological deficits observed were not critical.

Aneurysms of the posterior cerebral artery and approach selection in their microsurgical treatment: emphasis on the approaches: SAHEA and SCTTA

Aneurysms of the posterior cerebral artery (PCA) are infrequent and located in the central depth of the brain. Hence their optimal microsurgical management has not been discussed systematically, as institutions and/or neurosurgeons have only limited experience. The purpose of this communication is to report our considerations on this topic with emphasis on the selection of approaches by reviewing our 20 consecutive cases of PCA aneurysms out of more than 1,000 aneurysm patients seen over the past 15 years. Although the subtemporal approach appears to be prevalent in the literature, in our series we applied the pterional approach with or without selective extradural anterior clinoidectomy (SEAC) for P1, P1-P2 aneurysms, and either a selective amygdalohippocampectomy approach (SAHEA) or supracerebellar transtentorial approach (SCTTA) for P2 and P2-P3 aneurysms. Construction of an extracranial-intracranial EC-IC bypass, when necessary, in conjunction with parent artery occlusion or with trapping of aneurysms was adapted to selected approaches.

Treatment of Distal Posterior Cerebral Artery Aneurysms

OBJECTIVE

This is the largest contemporary series of distal posterior cerebral artery (PCA) aneurysms treated by use of endovascular coiling and stenting as well as surgical clipping, clip wrapping, and bypass techniques. We propose a new treatment paradigm.

METHODS

The location, size, type of aneurysm, clinical presentation, treatment, complications, and outcomes associated with 34 distal PCA aneurysms in 33 patients (15 females, 18 males; mean age, 44 years) were reviewed retrospectively.

RESULTS

The most common presenting symptom was headache in 19 (58%) followed by contralateral weakness or numbness in 6 (18%) and visual changes in 4 (12%). Eight aneurysms were giant. Of the remaining 26 aneurysms, 17 were fusiform/dissecting, 5 were saccular, and 4 were mycotic. Treatment was primarily endovascular in 22 patients, 12 of whom also had a concomitant surgical bypass procedure. Nine patients underwent microsurgical clipping, and 3 underwent combined treatment of clipping and coiling and/or stenting. There were no significant differences in outcomes between the groups (P = .078). The recurrence rate in patients undergoing coiling was 22% and 0% in patients undergoing clipping. Fourteen aneurysms (41%) involved treatment with an occipital artery-to-PCA bypass or an onlay graft. Compared with their preoperative status, these patients had significantly worse outcomes than those without a bypass (P = .013).

CONCLUSION

Bypass techniques for the treatment of distal PCA aneurysms are associated with a higher rate of complications than once thought. In our new treatment paradigm, bypass is a last resort and reserved for patients in whom balloon-test occlusion fails, who refuse parent-vessel sacrifice, and who cannot undergo primary stenting with coiling or clip wrapping.

Results of surgical management for posterior cerebral artery aneurysms: 7-year experience in the endovascular era

PURPOSE

Unlike most posterior circulation aneurysms, posterior cerebral artery (PCA) aneurysms can be surgically approached, we believe, without significant technical difficulty or procedural morbidity. We report our recent experience to assess procedural complications and clinical outcomes for PCA aneurysms.

METHODS

In our retrospective review of 15 consecutive patients with PCA aneurysms, six patients underwent surgical treatment, six patients had endovascular coiling, (three patients from the endovascular group also underwent surgical revascularization), and three patients were treated conservatively (medical or observation) (2001-2007). Clinical records were reviewed for: patient demographics; clinical presentation; aneurysm location, size, and morphology; treatment; procedural complications; outcome (clinical and angiographic).

RESULTS

Complete aneurysm obliteration with parent vessel or bypass patency was demonstrated by intraoperative angiography in all patients. One patient died and two patients suffered procedure-related permanent neurologic injury. Considering both surgical end endovascular treatment modalities, mortality was 8.3% and permanent morbidity was 16.6%. At mean clinical follow-up of 2-96 months (15.8 +/- 10.5 months), nine of ten patients had a Glasgow Outcome Score of 4 or 5. In patients who underwent bypass procedures, computed tomographic (CT) angiography or cerebral angiography demonstrated a patent functional bypass before the PCA occlusion.

CONCLUSIONS

Our findings for these 15 patients suggest the value of a multimodality of treatments for PCA aneurysms. Revascularization of the PCA can be performed with favorable technical results and clinical outcomes when the patency of the PCA cannot be preserved.

Endovascular management of posterior cerebral artery aneurysms. Initial experience

SUMMARY

The purposes of this study were to evaluate the efficacy and safety of the endovascular management of posterior cerebral artery aneurysms and compare the efficacy and safety of selective aneurysmal coiling and parent artery occlusion. We reviewed all cases with cerebral aneurysms and attention was paid to the patients with posterior cerebral artery aneurysms. Among 550 aneurysms, eight aneurysms in eight patients were located on the posterior cerebral artery, three of which presented with SAH, whereas five presented with different degrees of headache. Seven were located at the P2 segment and one at the P3 segment. One was a giant serpentine aneurysm, two were giant sac aneurysms, two were large and three were small. All aneurysms were successfully treated, five with selective aneurysmal coiling and three with parent artery occlusion. Two patients presenting with headache with giant aneurysms had suffered an aggravated headache for two weeks which then resolved. Others had an uneventful recovery. All patients were followed from 12 months to 56 months. Four selective aneurysmal coiling aneurysms received digital subtraction angiography, two of which needed another treatment and one was treated with parent artery occlusion, one of which recanalized slightly and one of which had further thrombosis. No rebleeding or any other symptom occurred. Whether selective aneurysmal coiling or parent artery occlusion was performed, endovascular management of PCA aneurysms was a safe and effective method. Under some conditions, parent artery occlusion was better than selective aneurysmal coiling.

Subtemporal approach for a P2–P3 junction aneurysm of the posterior cerebral artery

Aneurysms are seen rarely at the P2-P3 junction of the posterior cerebral artery (PCA). P2-P3 junction aneurysm surgery is challenging. Here, a successful clipping of a large P2-P3 junction aneurysm via a subtemporal approach is reported. A 26-year-old woman presented with a 6-month history of left occipito-parietal headache. Computed tomography (CT) scan, magnetic resonance imaging (MRI) and cerebral angiography revealed a 2-cm aneurysm at the P2-P3 junction of the left PCA. Successful neck clipping of the aneurysm was performed via a subtemporal approach without additional neurological deficits or surgical complications. Coil embolization has been suggested as the treatment of choice but PCA aneurysms are also good candidates for microsurgical clipping. The subtemporal approach is simple and safe in experienced hands. P2-P3 junction PCA aneurysms can be successfully clipped via the subtemporal approach without excessive brain retraction, resection of brain tissue or disruption of surface veins.

Posterior interhemispheric approach: surgical technique, application to vascular lesions, and benefits of gravity retraction

OBJECTIVE

To review an experience with the posterior interhemispheric approach applied to vascular lesions in the posterior midline, to examine the effects of patient position and gravity retraction of the occipital lobe, and to identify circumstances requiring increased exposure by sectioning the falx and tentorium.

METHODS

During a 6.5-year period, 46 posterior interhemispheric approaches were performed to treat 28 arteriovenous malformations, 10 dural arteriovenous fistulae, seven cavernous malformations, and one posterior cerebral artery aneurysm. Twenty-three patients were positioned prone and 23 patient were positioned laterally.

RESULTS

A standard posterior interhemispheric approach was used in 38 patients, and the occipital bitranstentorial/falcine approach was used in seven patients. A contralateral occipital transfalcine approach was used with one thalamic cavernous malformation. All lesions were resected completely and/or obliterated angiographically, with good neurological outcomes in 83% of patients and no operative mortality. Blood loss was lower, operative durations were shorter, postoperative cerebral edema was decreased, and visual outcomes were improved in patients positioned laterally.

CONCLUSION

The posterior interhemispheric approach, without additional dural cuts, is appropriate for most vascular lesions in the posterior midline. Gravity retracts the occipital lobes when patients are positioned laterally, enhancing operative exposure and reducing morbidity. Extension of the posterior interhemispheric approach to a transtentorial or transfalcine approach is required for falcotentorial dural arteriovenous fistulae and vein of Galen arteriovenous malformations, but is not usually necessary with cavernous malformations or other arteriovenous malformations.

Microsurgical anatomy and quantitative analysis of the transtemporal-transchoroidal fissure approach to the ambient cistern

OBJECTIVE

Surgical approaches to ambient cistern lesions are complex. We investigated the microanatomy of the transtemporal-transchoroidal fissure approach to the ambient cistern with emphasis on exposure of the posterior cerebral artery.

METHODS

Dissections were performed bilaterally in five silicone-injected cadaveric heads. Critical anatomic distances, specifically with reference to the P2 segment of posterior cerebral artery in relation to the inferior choroidal point and P2-P3 junction, were measured with digital calipers. Other landmarks (temporal lobe tip, points from the temporal base to the choroidal fissure) were included for quantitative analysis.

RESULTS

The transtemporal-transchoroidal fissure approach provided adequate exposure of the ambient cistern, minimized temporal lobe retraction, and allowed assessment of regional microanatomy. The mean distance from the temporal base to the choroidal fissure measured 18.09 mm (range, 16.9-21.9 mm). The distances from the choroidal fissure to P2 varied at the coronal plane of the inferior choroidal point (mean, 6.96 mm; range, 3.6-12.0 mm) and the P2-P3 junction (mean, 6.02 mm; range, 4.3-6.9 mm), respectively.

CONCLUSION

The transtemporal-transchoroidal fissure approach provides a corridor to the ambient cistern and P2-P3 junction while minimizing temporal lobe retraction and avoiding interruption of temporal lobe venous drainage. Because of widely variable vascular anatomy, access to posterior cerebral artery lesions using this approach requires preoperative imaging to identify the specific location of the P2-P3 junction.

Clinical Features of Aneurysms of the Posterior Cerebral Artery: A 15-year Experience with 21 Cases

OBJECTIVE:

To investigate the characteristic clinical behavior and develop guidelines for the clinical management of posterior cerebral artery aneurysms, we reviewed 21 cases treated during a 15-year period.

METHODS:

Between 1988 and 2002, we treated 21 patients (10 male, 11 female; mean age, 49.8 yr) with posterior cerebral artery aneurysms at Kumamoto University Hospital and its affiliated hospitals. Data relating to the clinical, radiological, and surgical approaches were analyzed.

RESULTS:

There were 20 saccular aneurysms, 6 of which were giant or large aneurysms, and 1 dissecting aneurysm. Of the 21 patients, 15 presented with subarachnoid hemorrhage; in 3 patients, an unruptured saccular aneurysm was found incidentally during an evaluation for other cerebral pathological conditions. Two patients presented with progressive homonymous hemianopsia because of the mass effect of the aneurysm, and 1 patient experienced the sudden onset of homonymous hemianopsia because of thrombosis of the aneurysm and afferent artery. Open or endovascular surgery was performed in 19 patients: 14 made a good recovery, 2 had a moderate disability because of angiospasm or infarction after aneurysm trapping, 1 had a severe disability because of angiospasm and cerebral contusion, and 2 died because of severe angiospasm. Of 2 conservatively treated patients, 1 made a good recovery but the other died as a result of rebleeding.

CONCLUSION:

Posterior cerebral artery aneurysms have specific clinical characteristics compared with aneurysms located elsewhere. The aneurysmal site and size and the surgical technique did not significantly influence treatment outcomes.

Relevance of occlusion test in endovascular coiling of posterior cerebral artery (p2 segment) aneurysms

SUMMARY

P2 segment aneurysms are located on the posterior cerebral artery (PCA) between the junction of the posterior communicating artery with the PCA and the quadrigeminal cisternal part of the PCA. We reviewed our experience with endovascular coiling in such aneurysms. Clinical and pre-procedural data from four patients, referred for endovascular treatment of P2 segment aneurysms, were retrospectively studied for factors influencing post-interventional neurological deficits caused by ischemia of the PCA distal territory. Balloon occlusion was done in three patients and patient tolerance was assessed using clinical and anatomic criteria. Embryologic and anatomic features of the PCA were reviewed. Balloon occlusion test and endovascular coiling of aneurysms was possible in three patients. Control angiogram after embolization showed elimination of aneurysms from the circulation and the distal PCA filled through leptomeningeal anastomoses. One patient deteriorated due to aneurysmal rupture soon after the balloon occlusion test and coiling could not be done. In the other three patients post-intervention CT and MRI images showed PCA territory infarcts in spite of demonstration of good collateral circulation distal to the occluded PCA. In conclusion, P2 aneurysms can be effectively treated by endovascular coiling without a balloon occlusion test. While the balloon occlusion test does not contribute to clinical decision-making it may be associated with potential morbidity and mortality.

Treatment strategy for aneurysms of the posterior cerebral artery

SUMMARY

The authors carried out a retrospective review of the records of 12 patients with aneurysms of the posterior cerebral artery (PCA). Four were asymptomatic, 1 presented with a mass effect, and 7 with a subarachnoid haemorrhage (SAH). Of the 7 ruptured aneurysms, 3 were embolized and 2 were clipped. However, 2 patients died from rebleeding before any treatment. Of the 5 unruptured aneurysms, 1 was embolized with coils but the remaining 4 have been conservatively observed. No aneurysms have ruptured during the follow-up period, and 3 have thrombosed spontaneously. According to our results, the PCA aneurysms should be treated aggressively in the early phase. Although the preservation of the anatomical integrity of the PCA should naturally be one of the prime objectives, PCA occlusion may sometimes be inevitable when treating large or fusiform aneurysms. On the other hand, conservative therapy is one of the options for the treatment of incidentally encountered unruptured ones, because these have the possibility of spontaneous thrombosis.

De novo distal posterior cerebral artery aneurysm

BACKGROUND

De novo aneurysms in the posterior circulation are very rare. The authors describe a first case of ruptured de novo posterior cerebral artery (PCA) aneurysm in the P3 portion.

CASE DESCRIPTION

A 52-year-old woman with ruptured de novo P3 aneurysm was treated by early endovascular obliteration using Guglielmi Detachable Coils (GDC). To prevent vasospasm, she received postoperative treatment with a hypertensive hypervolemia dilution and a calcium antagonist. She was discharged without neurologic deficits.

CONCLUSIONS

Aneuryms arising from peripheral segment of PCA are rare, and delayed surgical clipping has been recommended for these lesions. This is the first report of a de novo P3 ruptured aneurysm treated by endovascular embolization using GDC in the acute stage of subarachnoid hemorrhage. The characteristics of de novo posterior circulation aneurysms and the strategy for the distal PCA aneurysms are discussed.

Bilobed wide neck posterior cerebral artery aneurysm associated with fusiform basilar aneurysm, subarachnoid hemorrhage and chronic renal failure. A case report

SUMMARY

A 56 year-old woman presented with a ruptured bilobed wide neck aneurysm of the P2 segment of the PCA, atherosclerotic fusiform basilar artery aneurysm, subarachnoid bleeding with negative CT scan and chronic renal failure. She was managed by a cooperative approach involving neurosurgeons, neuroradiologist, neurointensivist, emergency room physicians, nurses and technicians. She underwent operation by proximal clipping for the aneurysm of the PCA. Postoperative neurological deficits include homonymous hemianopsia and ipsilateral third nerve palsy. The operation was performed through asubtemporal approach. At surgery, the aneurysm was located in the distal of the P2 segment of PCA, bilobed up and down, no definitive neck with small distal branches, and was treated by proximal clipping of the PCA aneurysm. The fusiform basilar artery aneurysm was severely atherosclerotic and left untouched. This is a rare case which required a high index of suspicion to detect subarachnoid bleeding from ruptured posterior fossa aneurysm, accurate prediction of the site of bleeding and the location of aneurysm location by conventional angiogram, MRI and MRA, and careful planned surgical strategy with the right approach for the P2 segment of the PCA aneurysm, complicated post operative care with airway management, triple H therapy, nutrition, additional measures and multiple hemodialysis.

Totally thrombosed giant P2 aneurysm: a case report and review of literature

The diagnosis and treatment of intracranial saccular giant aneurysms is still difficult despite developments in neuroradiology, neuroanesthesiology and micro-neurosurgery. These aneurysms are usually located on major intracranial arteries and are rarely on distal branches of these arteries. An extra-axial 4 x 5 cm mass lesion in the left mediobasal temporal region was detected on the CT and MRI examinations of a 37 year old male patient who was admitted to our institution with headache and slight right-sided hemiparesis lasting for 2 months. The lesion was avascular on angiography. Surgery proved that the lesion was a totally thrombosed giant aneurysm of the P2 segment of posterior cerebral artery (PCA). The P2 segment was clipped proximal to the aneurysm with pterional-transsylvian approach and the aneurysm was totally excised. Giant aneurysms of the P2 segment are rare and 15 cases have been reported in the literature. This report presents a rarely seen totally thrombosed giant P2 aneurysms and discusses the difficulties in diagnosis and treatment.

Surgical indications and microsurgical anatomy of the transchoroidal fissure approach for lesions in and around the ambient cistern

OBJECTIVE

Opening the temporal part of the choroidal fissure (CF) makes it possible to expose the crural cistern, the ambient cistern, and the medial temporal lobe. We examined the microsurgical anatomy and the surgical indications for use of the trans-CF approach.

METHODS

The microsurgical anatomy encountered in the trans-CF approach for lesions in and around the ambient cistern was studied in three cadavers. On the basis of these cadaveric studies, the trans-CF approach was used during surgery in three live patients with such lesions.

RESULTS

The angiographic "plexal point," which indicates the entrance of the anterior choroidal artery as it enters the temporal horn of the lateral ventricle, was thought to be a key anatomic landmark of the trans-CF approach. A cortical incision for entry into the temporal horn should be made in the inferior temporal gyrus to minimize the potential damage to the optic radiations and to the speech centers. After the CF is opened posteriorly to the plexal point between the tenia fimbria and the choroid plexus, the posterior cerebral artery (PCA) in the ambient cistern can be observed with minimal caudal retraction of the hippocampus. In this study, surgical procedures using the trans-CF approach were successfully performed on patients with high-positioned P2 aneurysms whose PCA ran close to the plexal point or higher, whose medial temporal arteriovenous malformations were fed mainly by the PCA, and whose tentorial hiatus meningiomas protruded into the temporal horn through the CF, with no resulting postoperative visual or memory disturbances.

CONCLUSION

The trans-CF approach is especially useful in surgery for lesions in and around the ambient cistern.

Management strategies for posterior cerebral artery aneurysms: a proposed new surgical classification

In a period of 10 years fifteen patients bearing sixteen aneurysms arising at the posterior cerebral artery were operated at our institution. Based on the approaches selected for each location a division of the posterior cerebral artery into three surgical segments is proposed. The first segment (S1), or anterior extends from the basilar artery bifurcation to the point where the artery reaches the level of the most lateral edge of the cerebral peduncle, the second segment (S2), or middle extends from the posterior limit of S1 to a point located just before the most medial extent of the artery in the quadrigeminal cistern (collicular point), and the third segment (S3), or posterior corresponds to the collicular point and to the portions of the posterior cerebral artery distal to it. Utilizing the concept of surgical segments all aneurysms in our series were satisfactorily exposed. Those arising at the S1 segment (8 cases) were operated either through a pterional or a pretemporal approaches; those from the S2 segment (6 cases) were operated either via the subtemporal or the subtemporal transventricular routes; and that arising from the S3 segment (1 case) was managed through the occipital interhemispheric approach. Among the aneurysms eleven were small, one was large, and four were large or giant. Ten of these aneurysms were surgically clipped, two coagulated, three treated by trapping and in one case the aneurysm was resected and the posterior cerebral artery was reconstructed by a termino-terminal anastomosis. The surgical results were considered good in all cases but one, where the patient died due to clinical complications three months after surgery. It is our belief that the use of this classification can provide the means to best select the most appropriate surgical approach to treat aneurysms arising at the posterior cerebral artery.

Specific characteristics and management strategies of cerebral artery aneurysms: report of eleven cases

Owing to the deep location of the posterior cerebral artery (PCA) and its close relationship with the brainstem and surrounding vital structures, surgical treatment of aneurysms in this region is complex. This study was undertaken in an attempt to better delineate the surgical risks of PCA aneurysms. A retrospective analysis was undertaken in 11 patients with PCA aneurysm surgically treated between 1988 and 1996 at Shinshu University and its affiliated hospitals. Data regarding surgical strategy, surgical complications and outcomes were analysed. Seven aneurysms were saccular (including one mycotic) and the other four were fusiform, dissecting, thrombosed and an infundibular dilatation. The locations of the aneurysms were at the P1 segment in two patients, P1-P2 junction in two, P2 segment in six and P3 segment in one. Six saccular non-mycotic aneurysms were treated with neck clipping and the other five aneurysms were treated each with proximal occlusion of the parent artery, excision of the aneurysm or wrapping. All aneurysms were satisfactorily exposed except one large saccular aneurysm. Surgical outcomes were either good recovery or moderate disability in 10 patients, and severe disability in one patient with a large aneurysm due to temporal lobe contusion. In conclusion it is the responsibility of the surgeon dealing with rare PCA aneurysms to be aware of these specific characteristics and to appreciate which surgical technique is appropriate for each patient.

Surgical approaches for the treatment of aneurysms on the P2 segment of the posterior cerebral artery

OBJECTIVE

The P2 segment of the posterior cerebral artery has remained a challenging region to expose surgically. We establish a surgical strategy for P2-segment aneurysms.

METHODS

Each segment of the posterior cerebral artery was classified according to Zeal and Rhoton's classification. Fourteen of 18 P2-segment aneurysms were surgically treated. The patient's outcome, the aneurysm location, and the surgical procedures were evaluated. A cadaveric study was performed to clarify the surgical view obtained via three different surgical approaches.

RESULTS

Nine aneurysms were clipped, two were trapped, one was coated, and one was excised with parent artery reconstruction. Cerebral revascularization techniques were used for three patients. The pterional approach exposed the anterior half of the P2a segment. The subtemporal approach revealed the P2a segment, but its exposure was restricted by its localization in the ambient cistern. Via the occipital interhemispheric transtentorial approach, the P2p segment was visible and could be manipulated. When the posterior half of P2a segment was high on a coronal view of magnetic resonance imaging, it was extremely hard to access via any approach.

CONCLUSION

A surgical strategy for the P2 aneurysm can be planned with accurate prediction of the aneurysm location. When the localization of an aneurysm on the posterior half of P2a segment is high, a resection of brain tissue may be required.

A case of posterior cerebral artery aneurysm associated with idiopathic bilateral internal carotid artery occlusion: case report

BACKGROUND

Aneurysms of the posterior circulation are challenging lesions to neurosurgeons, despite improvements in microsurgical techniques and advances in skull base approaches. We present a rare case of a posterior cerebral artery (PCA)-posterior communicating artery (PcomA) junction aneurysm associated with bilateral internal carotid artery (ICA) occlusion successfully treated with an endovascular procedure.

CASE DESCRIPTION

A 57-year-old female presented with sudden onset of severe headache and loss of consciousness. CT scan showed diffuse subarachnoid hemorrhage and acute hydrocephalus. The patient developed severe neurogenic pulmonary edema and shock. Although her neurogenic pulmonary edema did not resolve, she recovered from shock. However, her general condition was so critical and her vital signs so unstable, that direct surgery under general anesthesia was considered too risky. A cerebral angiogram showed complete occlusion of both internal carotid arteries without any Moyamoya vessels. A saccular aneurysm located at the right PCA-PcomA junction was seen. To obliterate the aneurysm and prevent rerupture, the patient underwent coil embolization via an endovascular approach under sedation with local anesthesia. The balloon remodeling technique was useful to prevent occlusion of parent arteries. Finally, four interlocking detachable coils (IDC) with a total length of 44 cm were used to completely obliterate the aneurysm using the balloon remodeling technique. The patient made a full recovery after treatment and the aneurysm remained obliterated 2 years after coil embolization.

CONCLUSIONS

We emphasize the advantages of the endovascular approach for the patient in critical condition. We believe that this is the first report of a PCA-Pcom junction aneurysm associated with bilateral ICA occlusion without moyamoya disease.

P2 aneurysm approached via the temporal horn: technical case report

OBJECTIVE AND IMPORTANCE

We report the use of a transcortical transventricular approach to a P2 aneurysm, which was located near the choroidal fissure, protruded into the temporal horn, and was considered to be too difficult to approach by the conventional subtemporal route.

CLINICAL PRESENTATION

An 81-year-old woman suddenly developed severe headache with vomiting and subsequently lost consciousness. Computed tomographic scans revealed a diffuse intraventricular hemorrhage and subarachnoid hemorrhage. Cerebral angiography disclosed a saccular aneurysm in the right P2 segment.

INTERVENTION

On the 16th day after admission, successful neck clipping was easily performed through the temporal horn via the inferior temporal gyrus. The postoperative course was uneventful.

CONCLUSION

This special approach may be preferable in such cases, because it protects the brain from the detrimental effects of strong temporal retraction and provides a wider working space.

Aneurysms of the posterior cerebral artery: do they present specific characteristics?

A series of 7 cases of PCA aneurysm treated between 1978 and 1992 were analytically reviewed together with 79 cases culled from the literature. In comparison to those localized elsewhere, PCA aneurysms are more frequently large, more frequently present with tumour-like symptoms and appear at an earlier age. Surgical outcome was evaluated in relation to clinical onset, site and size of the aneurysm, the surgical procedures adopted for excluding it and pre-operative clinical grading appeared to influence outcome. The fact that site, size and surgical technique do not significantly influence prognosis is probably due to the rich collateral flow present in the areas fed by the posterior cerebral artery. The authors conclude that, clinically speaking, PCA aneurysms should be considered as a separate group.

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Apresentamos caso de aneurisma gigante do segmento distal (P3) da artéria cerebral posterior. O aneurisma foi tratado microcirurgicamente pela via combinada proposta por Sano com clipagem do ramo terminal da artéria cerebral posterior próximo ao aneurisma. A paciente teve evolução pós operatória favorável, com lesão parcial e transitória do III nervo craniano. Revisão da literatura e discussão a respeito da anatomia e da abordagem cirúrgica são feitas. A raridade desta patologia justifica o relato deste caso.