Carotid Cave Aneurysm Research Articles

Management of Incidental Carotid Cave Aneurysm.

Incidental diagnosis of saccular aneurysms is more common with the advent of imaging techniques. Because of the severe morbidity and mortality that they can cause, treatment is chased for them, either microsurgical treatment or endovascular, even when they are diagnosed incidentally. Carotid cave aneurysms are rare, and they seem to have a more benign course compared to other intracranial aneurysms, probably related to the physical enveloping effect of the surrounding structures. Yet, their microsurgical treatment is a serious challenge technically for the neurosurgeon, with its severe morbidity and mortality for the patient. Endovascular techniques have their risks, too. In this paper, we analyzed and presented our series of incidentally diagnosed carotid cave aneurysms. The age, gender of patients, the size, laterality, and MR angiographic follow-up of aneurysms were reported. Their clinical results were noted. Fifty-six patients who had incidentally been diagnosed with 59 carotid cave aneurysms were followed up. No patient was microsurgically treated, but 15 patients had endovascular treatment for 15 aneurysms. The mean size of 15 treated aneurysms was 4.6 ± 2.1 (range = 2-10) mm, and it was 3.0 ± 1.5 (range = 1.7-10) mm for the untreated aneurysms (n = 44). There was no significant difference between the follow-up times of the treated and untreated groups (P = 0.487). The median follow-up of 59 aneurysms in 56 patients was 52 (mean = 49.6 ± 27.9, range = 1-124) months, with a total follow-up of 244 aneurysm years. None of the patients had subarachnoid hemorrhage related to carotid cave aneurysms during follow-up, and none of the aneurysms had shown growth. Two patients who had endovascular treatment had ischemic complications with minor neurologic deficits. Follow-up can be a reasonable option for the incidental aneurysms that are located and confined to the carotid cave. Additionally, TOF might be a reliable method for follow-up imaging of carotid cave aneurysms.

Retrospective review of 290 small carotid cave aneurysms over 17 years.

The carotid cave is a unique intradural region located along the medial aspect of the internal carotid artery. Small carotid cave aneurysms confined within this space are bound by the carotid sulcus of the sphenoid bone and are thought to have a low risk of rupture or growth. However, there is a lack of data on the natural history of this subset of aneurysms. The authors present a retrospective case series of 290 small (≤ 4 mm) carotid cave aneurysms evaluated and managed at their institution between January 2000 and June 2017. No patient presented with a subarachnoid hemorrhage attributable to a carotid cave aneurysm, and there were no instances of aneurysm rupture or growth during 911.0 aneurysm-years of clinical follow-up or 726.3 aneurysm-years of imaging follow-up, respectively. This series demonstrates the benign nature of small carotid cave aneurysms.

Case report of 2 Carotid cave aneurysms: Microsurgical anatomy and technical pitfalls

Case report of 2 Carotid cave aneurysms: Microsurgical anatomy and technical pitfalls

Anatomia Microcirúrgica do Segmento Clinóide da Artéria Carótida Interna e do Cavo Carotídeo

Embora a região clinóide seja comumente abordada pelos neurocirurgiões em várias afecções, sua anatomia e extremamente complexa e variável. O segmento clinóide da artéria carótida interna (ACI) se encontra na transição entre o seio cavernoso e o espaço subaracnóide, limitado pelos dois anéis durais. O segmento posteromedial do anel dural distal não tem contato com nenhuma estrutura óssea, esta peculiaridade anatômica facilita a formação do cavo carotídeo. Os anéis proximal e distal tornam-se relevantes por serem os limitesanatômicos. O entendimento do segmento clinóide é importante para o correto diagnóstico e abordagem dos aneurismas desta região. Controle proximal, clinoidectomia anterior, opções de clips fenestrados e auxílio do endoscópio são detalhes técnicos de grande utilidade no manejo dos aneurismas do cavo carotídeo.

Endovascular treatment of unruptured carotid cave aneurysms

Objective To summarize the characteristics of carotid cave aneurysms and to investigate the safety and efficacy of endovascular treatment for this kind of aneurysms. Methods From November 2013 to November 2016, the clinical data of 22 patients with unruptured carotid cave aneurysms undergoing endovascular treatment, at the Department of Neurosurgery, the First Affiliated Hospital of Harbin Medical University, were collected. Among them, 3 patients (14%) were male and 19 patients (86%) were female. Their clinical characteristics, outcomes, complications and follow-up results were analyzed retrospectively. Modified Rankin scale (mRS) was used to assess the outcomes and Raymond Scale was used to assess the safety and efficacy of endovascular treatment. Results All 22 patients were treated by stent assisted coiling. Raymond 1 was reported in 19 patients (86%) and Raymond 2 was achieved in 3 patients (14%). Thrombosis occurred in the stent in 1 patient during the operation who did not develop any neurological deficits after Tirofiban treatment. Ten patients underwent angiographic follow-up after 1 year and 9 patients achieved Raymond 1. The mRs score was 0 in all patients. Conclusions Carotid cave aneurysms seem to be more common in females. Endovascular treatment could be a safe and effective approach for carotid artery aneurysms. Key words: Intracranial aneurysm; Carotid cave; Endovascular procedures; Treatment outcome

Surgical clipping for large and giant unruptured paraclinoid aneurysms in hybrid operation theater

Objective To evaluate the clinical value and outcomes of surgical clipping for large and giant unruptured paraclinoid aneurysms. Methods A retrospective analysis was conducted on 8 patients (11 aneurysms) who underwent aneurysm clipping assisted with balloon occlusion in hybrid operation theatre at Neurosurgery Department of Xuanwu Hospital, Capital Medical University, from January 2014 to March 2017. All patients were females whose average age was 54.9±5.7 years. Results Among 11 aneurysms in this series, a total of 9 aneurysms were treated and included 8 large or giant paraclinoid aneurysms and 1 carotid cave aneurysm. Intraoperative radiography demonstrated that all 9 aneurysms were successfully obliterated, 1 patient developed occlusion of parent artery and 1 had severe stenosis of parent artery. Three patients encountered ischemic events postoperatively. The assessment at discharge indicated a Glasgow Outcome Score (GOS) of 5 in 5 patients, 4 in 1 case and 3 in 2 cases. At the follow-up which was conducted 1.5-39.5 [average: 10.7 (P25: 3.2, P75: 32.3)] months post operation, a GOS of 5 was reported 7 patients and 4 in 1 case. Vision acuity was improved in 7 patients and remained stable in 1 case. Conclusion Hybrid surgery seems to be able to facilitate clipping of large and giant unruptured paraclinoid aneurysms, but more studies are needed for exploration of proper interventional devices and methods. Key words: Intracranial aneurysm; Carotid artery, internal; Paraclinoid; Hybrid operation; Balloon occlusion; Surgical clipping

Risk Factors for Visual Impairments in Patients with Unruptured Intradural Paraclinoid Aneurysms Treated by Neck Clipping without Bypass Surgery

Although paraclinoid aneurysms are now frequently referred for endovascular treatment, the durability of obliteration is still to be determined. Therefore, direct surgery for paraclinoid aneurysms still remains indispensable. The present study aimed to evaluate the risk factors for the visual impairments in patients with unruptured intradural paraclinoid aneurysms. The data of 133 patients with 136 aneurysms treated by neck clipping without bypass surgery was evaluated. Visual impairments included decreased visual acuity and visual field defect. The aneurysm was classified into superior projecting aneurysm, ventral projecting aneurysm, and carotid cave aneurysm. Plug-in method was defined as filling interspace, which was formed between the internal carotid artery and the sutured dura in case of detachment of the dural ring. Postoperative new visual impairments were observed in 30 aneurysms (22%). During the follow-up period (median, 600 days), postoperative new visual impairments continued in 23 aneurysms (17%). Multivariate analysis showed that carotid cave location and plug-in method were related to new visual impairments at 30 days (odds ratio [OR], 2.6; 95% confidence interval [CI] 1.1-6.1; P= 0.031 and OR, 4.1; 95% CI 1.4-12; P= 0.008) and at 6 months (OR, 4.1; 95% CI 1.5-11; P= 0.005 and OR, 3.3; 95% CI 1.1-11; P= 0.045). The present study showed that carotid cave location and plug-in method during dural closures were related to postoperative continued visual impairments. Neurosurgeons should carefully consider the surgical indication for unruptured carotid cave aneurysms and avoid plug-in methods.

Prevention of Visual Function in the Operation of Paraclinoid Aneurysms

Objective: Paraclinoid aneurysms are aneurysms of the internal carotid artery (ICA) around the anterior clinoid process (ACP), including carotid cave and IC-ophthalmic aneurysms. To treat those aneurysms by direct clipping, it would need the removal of ACP and opening of the external dural ring, which might harm the optic nerves and their function. Then, the endovascular surgery is sometimes recommended especially in the case with carotid cave aneurysm. However, the recent paper reported that the complication and recurrence rates of endovascular surgery are relatively high. This direct surgery is useful, but difficult for the young and middle surgeon because those aneurysms are rare and dangerous lesion. We reviewed our recent cases and assessed the pitfall for prevention of visual function. Method: A total of eight cases with paraclinoid aneurysms treated in our hospital since December 2012 are assessed. Result: One case was treated by endovascular and seven were treated by direct surgery. Five cases were completely clipped with the removal of ACP, however, one of five showed visual impairment after surgery. In this case with right carotid cave aneurysm, ICG-VA during the surgery had shown disappearance of aneurysm and patency of ICA and perforators, however, her right vision gradually worsened 2days after surgery. Right ophthalmic artery was patent on her MRI/MRA and 3D-CTA, and her right optic disc was normal. Operative video was assessed, and showed that her right optic was contracted to ICA during the dissection of aneurysm and ophthalmic artery because of incomplete cutting of falcifalm fold, suggesting that this physiological compression to the optic nerve might cause the visual function. Conclusion: For prevention of visual function in the surgery of paraclinoid aneurysms, the complete opening of dural ring, the removal of optic strut, and the appropriate cutting of falcifalm fold are important as well as the removal of ACP. We emphasize that those techniques are essential as well as the removal of ACP to mobilize the optic nerve and perform the safe surgery.

Prevention of Visual Function in the Direct Surgery of Paraclinoid Aneurysms

Objective: For paraclinoid aneurysms, especially carotid cave aneurysm, endovascular intervention is recommendable. However, recent publication revealed that its rates of complication and recurrence are relatively high. Direct surgery, which could be useful, might be difficult for the young surgeon because those aneurysms are rare. One of seven cases with paraclinoid aneurysm treated at our department in 2013 deteriorated her vision 2 days after surgery. The problems are evaluated and discussed. Patient: A 54-year-old female patient with right carotid cave aneurysm had received the direct surgery with intradural ACP removal. Aneurysm had completely been closed with curved fenestrate clip. Intraoperative ICG showed disappearance of aneurysm and patency of arteries. Her right vision suddenly deteriorated 2 days later, although her MRI, MRA, and 3D-CTA showed patency of arteries including right opthalmic artery. Results: Operative video revealed that optic nerve had been contracted toward to ICA during dissection of aneurysm and opthalmic artery. It is suggested that this physical contraction could cause the optic nerve injury. Hence, the complete excision of distal dural ring, removal of optic strut and appropriate dissection of falcifalm fold might be important to easily mobilize ICA and prevent injury. Conclusions: Importance of other procedures including dural ring excision should be emphasized as well as ACP removal to complete safe surgery and prevent visual function.

困難を極めた症例・特別なテクニックを要した症例 特異な内頚動脈りゅうに対する術中の工夫

We present 3 patients with unusual internal carotid artery (ICA) aneurysms who underwent neck clipping with various intraoperative adjuncts. Case 1. A 64-year-old female underwent surgery of a large intracavernous ICA aneurysm because it enlarged significantly after 4 years of observation. Suction decompression via the catheter for intraoperative angiography was quite effective to dissect and clip the large aneurysm in the cavernous sinus. Case 2. A 74-year-old male with a re-grown aneurysm on the anterior wall of the ICA. The ruptured aneurysm had initially been clipped 3 years before. The follow-up angiography revealed that a slight neck remnant became prominent. A balloon test occlusion resulted in no neurological deficits. Because of the severe adhesion between the frontal lobe and aneurysm with the previous clips, we dissected the aneurysm and clips subpially from the brain. Then during the temporary trapping of the ICA, clips were applied parallel to the ICA, catching the normal wall of the ICA under the enlarged monitoring view of the endoscope. Case 3. A 41-year-old female with an angiographically occult ruptured aneurysm at the ICA-posterior communicating artery (PcomA). The aneurysm reruptured during the surgery on the ipsilateral unruptured carotid cave aneurysm that had been supposed as the ruptured aneurysm before surgery. The aneurysm was blind under the microscope because the aneurysm was tiny and located posteriorly. Therefore, the aneurysm was clipped by catching the intact wall of the ICA and PComA beyond the lesion under the simultaneous monitoring of microscope and endoscope. None of the 3 cases showed postoperative morbidity. In conclusion, we should anticipate all intraoperative problems in treating cerebral aneurysms and prepare all adjuncts for surgery previously.

Radiometric analysis of paraclinoid carotid artery aneurysms.

Classification of paraclinoid carotid artery (CA) aneurysms based on their associated branching arteries has been confusing because superior hypophyseal arteries (SHAs) are too fine to appear opacified on cerebral angiograms. The authors performed a retrospective radiometric analysis of surgically treated paraclinoid aneurysms to elucidate their angiographic and anatomical characteristics. A retrospective analysis was made of 85 intradural paraclinoid aneurysms in which the presence or absence of branching arteries had been determined at the time of surgical clipping. The lesions were classified as supraclinoid, clinoid, and infraclinoid aneurysms based on their relation to the anterior clinoid process on lateral angiograms of the CA. The direction of the aneurysms were measured according to angles formed between the medial portion of the horizontal line crossing the aneurysm sac and the center of the aneurysm neck on anteroposterior angiograms. Branching arteries were associated with 68 aneurysms, of which 28 were ophthalmic artery (OphA) lesions (32.9%) and 40 were SHA ones (47.1%); associated branching arteries were absent in 17 aneurysms (20%). Twenty-five aneurysms (29.4%) were located at the supraclinoidal level, 46 (54.1%) at the clinoidal, and 14 (16.5%) at the infraclinoidal. The majority of aneurysms identified at the supraclinoidal level were OphA lesions (44%) or those unassociated with branching arteries (48%), with mean directions of 57 degrees or 67 degrees, respectively. At the clinoidal level, the mean directions of aneurysms were 76 degrees in six lesions unassociated with branching arteries (13%), 43 degrees in 16 OphA lesions (35%), and -11 degrees in 24 SHA ones (52%). All aneurysms at the infraclinoidal level arose at the origin of the SHAs, with a mean direction of -29 degrees, and most of these were embedded in the carotid cave. Aneurysms arising from the SHA can be distinguished from those not located at an arterial division by cerebral angiography, because SHA lesions are usually located at the medial or inferomedial wall of the internal carotid artery at the clinoidal or infraclinoidal level. Their distribution correlates well with the reported distribution of SHA origins. The carotid cave aneurysm is a kind of SHA lesion that originates at the most proximal intradural CA.

Guidewire-Induced Carotid Cavernous Fistula

A rare case of carotid cavernous fistula occurring during endovascular embolization of the left carotid cave aneurysm in a 48-year-old female is reported. It was thought to be caused by the tear of a small branch derived from the intracavernous internal carotid artery while the guidewire was passing the sharp posterior bend of the intracavernous internal carotid artery. The left carotid cave aneurysm was completely occluded with five Guglielmi detachable coils assisted by neck plasty technique. It was decided to follow-up the carotid cavernous fistula since it was asymptomatic. Follow-up angiogram performed two weeks later revealed spontaneous obliteration of the carotid cavernous fistula.

内頸動脈硬膜輪近傍動脈瘤の血管内治療

Aneurysms arising around the carotid siphon, named juxta-dural ring aneurysms, are different from other cerebral aneurysms. These aneurysms are partially or totally covered with the dura mater and surrounded by the bone or the optic nerve. These anatomical specificity makes surgical access and clipping difficult, compared with other aneurysms. In our experience with endovascular treatment of the cerebral aneurysm over the past 4 years, 32 (28.8%) out of 111 patients harbored juxta-dural-ring aneurysms, including 5 males and 27 females whose age ranged between 33 and 76 years (average 57.5 years old). Seven patients suffered from subarachnoid hemorrhage, 3 in Grade 2, 3 in Grade 3 and 1 in Grade 4. Of 25 patients whose aneurysms were intact, 2 patients developed visual disturbance and 23 were asymptomatic. There were 28 small aneurysms and 4 large aneurysms. Giant aneurysms were not included in this study. Eight of them are broad necked. Twelve aneurysms arose distal to the origin of the ophthalmic artery and 20 did proximal, including 5 “carotid cave aneurysms.”“Extradural cavernous aneurysms”were excluded.Reasons of indication of endovascular treatment were surgically difficult case in 26, surgically unsuccessful case in 2, poor medical condition in 1 and patient's own will in 3. All these 32 aneurysms were occluded with detachable coils with preservation of the carotid artery. Angiographical results were complete occlusion in 12 (37.5%), dome filling in 13 (40.6%) and residual neck in 7 (21.9%). In the follow-up, complete occlusion was seen in 17 (53.1%), dome filling in 11 (34.4%) and residual neck in 4 (12.5%). Clinical results were good recovery in 29 (90.6%), moderately disabled in 2 (6.3%), severely disabled in 1 (3.1%) and dead in 0 (0%). Of 25 non-ruptured aneurysms, all the patients obtained GR, but there was no visual improvement in 2. Only 1 patient developed hemiparesis caused by embolic stroke due to inadequate heparinization in spite of complete occlusion of the aneurysm and intact carotid artery.Otherwise no serious complications occurred. In the follow-up period from 6 months to 4 years, no bleeding or rebleeding was observed. In our experience over a relatively short period, results are satisfactory. Considering surgical difficulty and results, we conclude that endovascular treatment is useful for carotid aneurysms around the siphon (juxta-dural ring aneurysm). However, special attention should be paid in choosing treatment of intact aneurysms, in which the risk of rupture is not high in the natural course.

Computer-generated surgical simulation of morphological changes in microstructures: concepts of “virtual retractor”

The author's goal was to develop a computer graphics model to simulate the displacement and morphological changes that are caused by the retraction of fine intracranial structures. The authors developed an application program to interpolate the contour of models of an artery and a retractor. The center of the displacement was determined by spatial coordinates, and the shape of the displacement of the arterial model was calculated by using a cosine-based formula with representation of a brain retractor. This computer graphics model was applied to the simulation of the displacement and morphological changes that occur when retraction is performed in the optic nerve. An illustrative case is presented, in which the optic nerve was displaced by a retractor to simulate the surgery performed in a carotid cave aneurysm of the internal carotid artery. The authors have named this methodological tool “virtual retractor.” This new navigational system for open microneurosurgery would be useful in teaching surgical microanatomy and in presurgical operative planning.

Asymptomatic, Unruptured Carotid-Ophthalmic Artery Aneurysms: Angiographical Differentiation of Each Type, Operative Results, and Indications

Background Some types of carotid-ophthalmic artery aneurysms are still difficult to clip successfully because their exposure requires opening the cavernous sinus and/or retracting the optic nerve. It is useful to know the complications and to determine the type of aneurysm preoperatively for the management of carotid-ophthalmic artery aneurysms. Methods The operative results in 15 patients with asymptomatic unruptured carotid-ophthalmic artery aneurysms were surveyed. The aneurysms were small in all the patients, and they underwent direct operation. Four patients presented with other ruptured aneurysms, four with other diseases (infarction, trauma, or pituitary adenoma), and seven were evaluated with magnetic resonance angiography for symptoms such as vertigo or headache. Among them, five had carotid cave aneurysms and one had paraclinoid aneurysm. Results Neck clipping was performed in 13 patients. Postoperatively, ipsilateral visual loss was encountered in one patient, and ipsilateral visual field defect was encountered in three patients. The visual field defect was lower nasal quadrant hemianopsia in two patients and lower hemianopsia in one patient. The cause of this complication was suspected to be retraction and/or the heat of the drill near the optic nerve. It seemed to be possible to distinguish the carotid cave or the paraclinoid aneurysm from the other carotid-ophthalmic aneurysms using carotid angiography preoperatively. Conclusion When direct operation is performed for a carotid-ophthalmic artery aneurysm, care must be taken to avoid optic nerve injury caused by the retraction and/or the heat of the drill.

Micro-anatomical study of the carotid cave.

The surgical treatment of aneurysms located in the carotid cave is often hazardous and difficult. We studied the micro-anatomy of the carotid cave and its neighbourhood by microscopic observation and histological examination using 50 sides from 25 autopsy cases. The carotid caves were found in 34 out of the 50 sides (68%) examined and were usually located in the posteromedial aspect of the carotid dural ring. They were classified into three types according to the topographic micro-anatomy: the slit-type (17/50, 34%) which showed a small, thin recess of the dura mater with fine connective tissue loosely adhered to the carotid wall; the pocket-type (12/50, 24%) which had a definite dural pouch with the apex attached to the vessel wall; and the mesh-type (5/50, 10%) which formed a slit- or pocket-type dural cave covered with a mesh-like dural roof. The remaining 16 sides (32%) showed tight dural attachment without any caval structure around the dural ring. The posteromedial portion of the carotid dural ring had no contact with any bony structure, and this distinct anatomical feature thus appear to facilitate the formation of the carotid cave. Furthermore, the availability of this potential space and the closely situated origin of the superior hypophyseal artery as well as the haemodynamic effect of the internal carotid artery may allow the development of the carotid cave aneurysm.

Anatomical location of carotid cave aneurysms

Seven carotid cave aneurysms were studied with various imaging techniques and at surgery. The carotid cave aneurysm projects medially with most of it overlying the sella turcica. The aneurysm partially overlies the anterior loop of the cavernous carotid artery and the anterior loop always partially overlies the sella turcica in these cases. The site of the cave aneurysm corresponds well with an area of the carotid artery observed on dissection studies which is adjacent to the sella. This parasellar area differs from the carotid cave in that it is below the dural ring and is not reinforced by the bone of the carotid sulcus. The findings explain the medial projection of the cave aneurysm in that this is the direction of least resistance which in turn also corresponds with the site of maximal force of the flowing blood.

Juxta-dural ring aneurysmの分類と治療法

Surgical treatment of internal carotid artery aneurysms around the carotid siphon is an art that is described elaborately in this paper. The surgical approach to the aneurysms in this region, is as follows: 1) A fronto-temporal approach with the patient in a 45° semi-sitting position to decrease venous pressure. 2) A Dolenc's approach cutting a part of the dura mater of the superior orbital fissure to facilitate removal of the anterior clinoid process and unroofing of the optic canal. 3) Opening of the medial triangle followed by transection of the optic canal dural sheath. Carotid siphon aneurysms can be divided into 3 groups anatomically: aneurysms of the ophthalmic segment (C2), those of the clinoid segment (C3), and those of the horizontal segment (C4). We present 34 cases of aneurysms arising from the C2 or C2/3 segment, 15 cases arising from the C3 or C3/4 segment, and 11 cases arising from the C4 segment. Anatomic localization of the aneurysms was established preoperatively by angiography and three-dimensional CT imaging. Small aneurysms of the ophthalmic segment projecting inferomedially can be clipped using a contralateral approach via the prechiasmatic root.Aneurysms of the ophthalmic segment projecting superiorly can be clipped following resection of the anterior clinoid process. The clinoid process should be resected intradurally with direct visualization of the aneurysms. Straight side-angled clips are suitable for these aneurysms. Carotid cave aneurysms, which include aneurysms of the ophthalmic segment oriented inferomedially and of the clinoid segment projecting postero-medially, can be clipped using curved fenestrated clips via Dolenc's extradural approach. For accurate clipping, opening of the medial triangle and full mobilization of the IC at the clinoid segment and optic nerve by unroofing the optic canal are required.Aneurysms of the horizontal portion are clipped after full exposure of the artery in the cavernous sinus only when the aneurysms are large and symptomatic. We used the fronto-temporal and Dolenc's approaches and applied fenestrated clips to aneurysms oriented postero-medially and straight or oblique clips to aneurysms projecting antero-laterally. Out of 52 aneurysms that underwent surgical clipping, 46 resulted in good post-operative recovery. There were 3 deaths secondary to complications of vasospasm and 3 cases with postoperative visual loss. We highlight the classification of these aneurysms and the surgical techniques we had employed.

Carotid ring 近傍の脳動脈瘤の分類と治療

Carotid artery aneurysms arising near the dural ring and the ophthalmic segment pose conceptual and technical controversies with regard to their classification and the extent of anterior skull base exposure. We review 58 operated patients with 60 such aneurysms and propose surgical procedure-orientated classification. According to the direction and size of the aneurysms, we classified them into 4 categories: supraoptic type, suboptic type, paraophthalmic type and global type. The supraoptic type include true ophthalmic artery aneurysms and “blister aneurysms” at the anterior wall of the carotid artery. The suboptic type arising at the superior hypophyseal artery necessitates the optic canal opening for obliteration with fenestrated clips. The paraophthalmic type had no branches near the aneurysm and opening the optic canal and removal of the anterior clinoid process is usually not necessary. The global type is often found by visual symptoms, and extensive exposure near the distal ring is necessary. Aneurysms arising near the dural ring have been frequently reported and the normenclature and the indication of the treatment have seemed to be confused. The risk of causing subarachnoid hemorrhage is the most important concern and the anatomical relation of the aneurysm and the distal ring is critical. When the C2 and C3 border is defined as the distal ring, the terminology of the nearby aneurysms becomes simple. However, accurate preoperative assessment of the border from the imaging study is not always possible. That is why the distal ring runs obliquely along the longitudinal axis of the C2 and C3, and the branching point of the ophthalmic artery does not always correspond to the C2 and C3 border. We discuss surgical indication and our understanding of reported aneurysms near the distal ring such as infraclinoidal aneurysm, transitional cavernous aneurysm and carotid cave aneurysm.

Considerations on Surgical Classification and Treatment of the Carotid Cave Aneurysm

Summary: In the intradural proximal internal carotid artery aneurysms, various concepts and analyses have been proposed. In this paper, concept of the carotid cave aneurysms including anatomical consideration and surgical technique is described. When the carotid cave aneurysm is found after subarachnoid hemorrhage or incidentally, surgical treatment is usually advised. Regarding surgical management, the pterional approach is used with unroofing the optic nerve and removing the anterior clinoid process; the carotid artery mobilized and the clipping is performed with a ring clip with laterally curved blades.