Radiometric analysis of paraclinoid carotid artery aneurysms

Investigation of paraclinoid aneurysm formation by comparing the combined influence of hemodynamic parameters between aneurysmal and non-aneurysmal arteries

Numerous studies have evaluated the effects of hemodynamic parameters on aneurysm formation. However, the reasons why aneurysms do not initiate in intracranial arteries are still unclear. This study aimed to investigate the influence of hemodynamic parameters, wall shear stress (WSS) and strain, on aneurysm formation by comparing between aneurysmal and non-aneurysmal arteries. Fifty-eight patients with paraclinoid aneurysms on one side were enrolled. Based on magnetic resonance angiography, each patient's left and right internal carotid arteries (ICAs) were reconstructed. For a patient having an aneurysm on one side, the ICA with the paraclinoid aneurysm was defined as the aneurysmal artery after eliminating the aneurysm, whereas the opposite ICA without aneurysm was defined as the non-aneurysmal artery. Computational fluid dynamics and fluid-structure interaction analyses were then performed for both aneurysmal and non-aneurysmal arteries. Finally, the relationship between high hemodynamic parameters and aneurysm location was investigated. For aneurysmal arteries, high WSS and strain locations were well-matched with the aneurysm formation site. Also, considerable correlations between high WSS and strain locations were observed. However, there was no significant relationship between high hemodynamic parameters and aneurysm formation for non-aneurysmal arteries. The findings are helpful for understanding aneurysm formation mechanism and encouraging further relevant research.

Unruptured Paraclinoid Carotid Aneurysms Occur More Frequently in Younger Ages

Purpose

We investigated the age distribution of cerebral saccular aneurysms in various locations to clarify the differences by location and discuss the mechanism of formation.

Materials and Methods

We retrospectively assessed clinical material obtained from 1,252 unruptured aneurysms treated with endovascular embolization between 2004 and 2019. Age, sex, laterality, and size were investigated by the location of aneurysms, classified as cavernous internal carotid artery (ICA), paraclinoid ICA, supraclinoid ICA, anterior communicating artery, anterior cerebral artery, middle cerebral artery, basilar artery complex, and posterior inferior cerebellar artery. Paraclinoid aneurysms were subclassified into 3 patterns according to their projecting direction: S-type, with superior protrusion; M-type, with medial protrusion; and P-type, with posteroinferior protrusion.

Results

There was no significant difference by location for sex, laterality, and size. The mean age of patients with paraclinoid aneurysms (56.5 years old) was significantly lower than that of other aneurysm patients (64.3 years old). Notably, 40% of the patients with M-type aneurysms were <50 years old. This percentage was significantly higher than that of aneurysms at other locations (P<0.05).

Conclusion

We found a young female predominance for patients with paraclinoid carotid aneurysms. This study may suggest that congenital factors contribute to paraclinoid aneurysm formation as well acquired factors, such as hemodynamic stress, atherosclerotic wall damage, and local inflammation.

Impact of Anterior Clinoidectomy on Visual Function After Paraclinoid Carotid Artery Aneurysm Surgery: Power-Drill Versus No-Drill Technique

BACKGROUND

Few studies have attempted to make a direct comparison of the risk of visual impairment following extradural anterior clinoidectomy (EAC) with and without the use of a power drill.

OBJECTIVE

To evaluate postoperative visual outcomes between groups of patients with paraclinoid carotid artery aneurysms (PCAAs) who underwent surgical clipping with and without the use of a power drill during EAC.

METHODS

Between January 2010 and November 2019, 90 patients, 7 with ruptured and 83 with unruptured PCAAs, underwent clipping surgery at our hospital. The authors retrospectively analyzed postoperative visual complications from the medical records of these patients.

RESULTS

Among the 85 patients (excluding 3 patients with disturbance of consciousness caused by subarachnoid hemorrhage and 2 patients with preoperative visual disturbance) evaluated, EAC was conducted using a power drill in 64 patients and using a microrongeur in 21 patients. Permanent postoperative visual impairment developed in 14 (21.9%) patients in the drill group: 9 patients had ipsilateral lower nasal quadrant hemianopsia (ILNQH) and 5 patients had ipsilateral visual acuity reduction. Transient ILNQH developed in only 1 patient in the no-drill group. The incidence of permanent postoperative visual impairments was significantly lower in the no-drill group than in the drill group (P = .020). Seventeen (26.6%) patients developed transient oculomotor nerve palsy in the drill group, while no patients developed oculomotor nerve palsy in the no-drill group.

CONCLUSION

EAC using a microrongeur versus a power drill significantly improved visual outcomes after clipping surgery for PCAAs.

Predictor of Visual Impairment Following Paraclinoid Aneurysm Surgery: Special Consideration of Surgical Microanatomy Related to Paraclinoid Structures

BACKGROUND

Microsurgical clipping with extradural anterior clinoidectomy (EDAC) for paraclinoid aneurysm is an established technique with good angiographic outcomes, although postoperative worsening of visual acuity remains a concern. Multiple reports show visual acuity deteriorating after clipping, yet the cause remains unclear.

OBJECTIVE

To analyze results of asymptomatic paraclinoid aneurysm surgeries treated with EDACs, specifically focusing on the microanatomy of paraclinoid structure dissection. This determined the causes of delayed visual impairment and microsurgical indications.

METHODS

Results of the treatment with EDAC of 94 patients with cerebral aneurysm and normal preoperative visual acuity but also full visual fields were retrospectively analyzed.

RESULTS

The mean aneurysm size was 6.2 (±3.3) mm. Clipping was performed in 87 cases and trapping in 7 cases. Complete angiographic occlusion was observed in 91 patients. In 26 cases, a postoperative visual deficit occurred. A total of 20 cases exhibited partial visual field deficits, including 5 who were asymptomatic. Visual deficits were only detectable by postoperative ophthalmologic testing. Six showed light perception impairment or blinding. Of the 15 patients with symptomatic partial visual field deficits, 5 showed improvement at follow-up. Visual deficits persisted in 22 patients at the last follow-up. Multivariate logistic regression analysis revealed that medial projecting aneurysm (adjusted odds ratio [OR]: 10.43) and the opening of the carotidoculomotor membrane (adjusted OR: 5.19) were significantly related to visual impairment.

CONCLUSION

Excess dissection of carotidoculomotor membranes causes postoperative delayed visual worsening. For treating small, asymptomatic paraclinoid aneurysms, carotidoculomotor membranes should not be opened, and microsurgical clipping should not be performed for preoperative asymptomatic medial projecting aneurysms.

Microsurgical Treatment of Paraclinoid Aneurysms by Extradural Anterior Clinoidectomy: The Fujita Experience

Introduction:

Paraclinoid aneurysms pose technical difficulty in their approach, mainly because of their close proximity to neurovascular structures, deeper location, and a smaller corridor. Extradural anterior clinoidectomy is a highly beneficial technique in such cases, making more space to deal with these aneurysms. We describe our method of performing extradural anterior clinoidectomy in such patients.

Materials and Methods:

A total of 33 cases of paraclinoid internal carotid artery aneurysms presenting to Fujita Health University Banbuntane Hospital, Japan, were included. Females comprised the majority with 32 cases; the mean age was 54.8 years (range: 35–74 years). The mean size of the paraclinoid aneurysm was 5.3 mm (range: 3–12 mm).

Results:

Nine paraclinoid aneurysms were found projecting dorsally, 7 laterally, and 17 medially (Kazuhiko Kyoshim et al's. classification). An immediate complete occlusion rate of 100% was present. Visual disturbance was found in 6.2% of our patients. One of our patients developed permanent loss of vision.

Conclusion:

Extradural anterior clinoidectomy enables a better exposure to paraclinoid aneurysms. Precise anatomical knowledge along with microsurgical tactics is required to prevent and manage potential complications to achieve good outcomes.

Role of superior hypophyseal artery in visual function impairment after paraclinoid carotid artery aneurysm surgery

OBJECT

Although a number of studies have assessed the surgical treatment of paraclinoid-segment carotid artery aneurysms and resulting visual complications, less attention has been given to the results with respect to the superior hypophyseal artery (SHA). The authors evaluated the relationship between the aneurysm, the SHA itself, and postoperative visual function in patients with ruptured and unruptured SHA aneurysms.

METHODS

From January 1991 through December 2013, 181 patients with 190 paraclinoid carotid artery aneurysms received treatment at Shinshu University Hospital and its affiliated hospitals. The authors retrospectively analyzed charts, operative records, operative videos, and neuroimaging findings for these patients with or without postoperative visual complications.

RESULTS

The authors identified 72 SHA aneurysms in 70 patients (mean age 58 years). Of 69 patients (1 patient died) evaluated, postoperative visual complications occurred in 9 (13.0%). Although the aneurysm size and SHA sacrifice did not lead to postoperative visual impairment, simultaneous treatment of bilateral aneurysms was a risk factor for postoperative visual complications.

CONCLUSIONS

Unilateral SHA impairment may be safe (i.e., it may not induce ischemia of the optic pathway) for many, but not all, patients with SHA aneurysm.

Microsurgical anatomy of the carotid cave

BACKGROUND

The carotid cave was first described more than 20 years ago, but its relationships to the dural rings defining the clinoid segment of the internal carotid artery (ICA), the carotid collar, and the adjacent osseous structures need further definition.

OBJECTIVE

To further define the microanatomy of the carotid cave and its relationships to the adjacent structures.

METHODS

: The cave and its relationships were examined in cadaveric specimens using 3 to 40× magnification.

RESULTS

The cave is an intradural pouch, found in 19 of 20 paraclinoid areas, that extends below the level of the distal dural ring between the wall of the ICA and the dural collar surrounding the ICA. The distal dural ring is tightly adherent to the anterior and lateral walls of the ICA adjacent the anterior clinoid process and optic strut but not on the medial and posterior sides of the artery facing the upper part of the carotid sulcus where the carotid cave is located. The superior hypophyseal artery frequently arises in the cave. The depth and circumferential length of the cave averaged 2.4 mm (range, 1.5-5 mm) and 9.9 mm (range, 4.5-12 mm), respectively. Aneurysms arising at the level of the cave, although appearing on radiological studies to extend below the level of the upper edge of the anterior clinoid, may extend into and may be a source of subarachnoid space.

CONCLUSION

The surgical treatment of aneurysms arising in the cave requires an accurate understanding of the relationships of the cave to the ICA, dural rings, and carotid collar.

Unruptured non-branching site aneurysms located on the anterior (dorsal) wall of the supraclinoid internal carotid artery: aneurysmal characteristics and outcomes following endovascular treatment

BACKGROUND

This study was undertaken to evaluate the aneurysmal characteristics and clinico-radiological outcomes of unruptured non-branching site aneurysms located on the anterior (dorsal) wall of the supraclinoid internal carotid artery (ICA).

METHODS

The data of 34 patients that underwent endovascular treatment for 36 unruptured ICA anterior wall aneurysms were reviewed. ICA anterior wall aneurysms were defined as aneurysms that projected superiorly from the anterior wall of the ICA ophthalmic (n = 35) or communicating (n = 1) segment on lateral angiograms, without any branch vessel relationship. In addition, aneurysmal characteristics and treatment outcomes were compared with those of 60 unruptured aneurysms originating from the posterior (ventral) wall of the ICA ophthalmic segment.

RESULTS

Patients with an ICA anterior wall aneurysm frequently had a mirror aneurysm on the contralateral side (14.7 % versus 3.3 %) or another ICA aneurysm (35.3 % versus 15 %). Two of the 36 ICA anterior wall aneurysms exhibited ICA narrowing suggestive of dissection, and another five had dysplastic ICA dilatation around the neck. Stent-assisted embolization was more frequently performed for ICA anterior wall aneurysms (66.7 % versus 36.7 %) because of unfavorable dome/neck (mean, 1.21) and aspect (mean, 1.15) ratios, and because of microcatheter instability associated with superior aneurysmal projections against the abrupt curvature of the carotid siphon. Procedure-related thromboembolic complications occurred in three patients in the anterior aneurysm group, but no patient deteriorated clinically. Immediate radiological outcomes were more unfavorable for ICA anterior wall aneurysms (residual sac, 36.1 % versus 16.7 %). Nevertheless, rates of recanalization (2.9 % versus 5.2 %) and progressive occlusion (24.7 % versus 8.1 %) during follow-up slightly favored ICA anterior wall aneurysms. Two stent-treated ICA anterior wall aneurysms developed asymptomatic ICA steno-occlusion (8.3 %).

CONCLUSIONS

Stent-assisted embolization is safe and effective for the treatment of unruptured ICA anterior wall aneurysms exhibiting unfavorable aneurysmal geometries and projections for coil embolization.

Visual sequelae after consensus-based treatment of ophthalmic artery segment aneurysms: the Johns Hopkins experience

BACKGROUND

To determine the anatomic and visual outcomes of patients with ophthalmic artery segment aneurysms treated at The Johns Hopkins Hospital using a consensus-based treatment algorithm.

METHODS

Retrospective record review of a prospectively accrued case series of 88 patients (101 aneurysms) treated between January 2004 and July 2009. Presenting symptoms and aneurysm parameters were recorded for all subjects. Treatment strategy for all patients was determined by consensus among neurosurgeons, neurointerventionalists, neurologists, and neuroophthalmologists meeting to review the clinical cases on a weekly basis. Final clinical outcomes (aneurysm control, functional status, and vision) were ascertained from in-house examinations, medical records, telephone interviews, or a combination of these methods. Risk factors for visual or other complications were evaluated.

RESULTS

An optic neuropathy was present in at least 30 (34%) of 88 patients after treatment. Presumed new visual loss occurred in 24 (27%) of these patients. The remaining 6 patients had preexisting optic neuropathy-related visual loss that worsened after treatment. No patient with a preexisting optic neuropathy improved following treatment.

CONCLUSION

Ophthalmic artery segment aneurysms present a treatment challenge because of their anatomic complexity and relationship to critical neural structures, particularly the visual sensory pathway. We have adopted a consensus-based treatment approach in an effort to optimize patient outcomes and aneurysm control. Although our approach resulted in durable treatment of the aneurysm, a sizable proportion of patients experienced new vision loss after treatment, and no patient with preexisting visual loss related to their aneurysm experienced visual improvement after treatment. We recommend that all patients with ophthalmic artery aneurysms receive careful and thorough preprocedural counseling to ensure they are aware of the risks and benefits of treatment regardless of the method used.

The avoidance of microsurgical complications in the extradural anterior clinoidectomy to paraclinoid aneurysms

OBJECTIVE

Paraclinoid segment internal carotid artery (ICA) aneurysms have historically been a technical challenge for neurovascular surgeons. The development of microsurgical approach, advances in surgical techniques, and endovascular procedures have improved the outcome for paraclinoid aneurysms. However, many authors have reported high complication rates from microsurgical treatments. Therefore, the present study reviews the microsurgical complications of the extradural anterior clinoidectomy for treating paraclinoid aneurysms and investigates the prevention and management of observed complications.

METHODS

Between January 2004 and April 2008, 22 patients with 24 paraclinoid aneurysms underwent microsurgical direct clipping by a cerebrovascular team at a regional neurosurgical center. Microsurgery was performed via an ipsilateral pterional approach with extradural anterior clinoidectomy. We retrospectively reviewed patients' medical charts, office records, radiographic studies, and operative records.

RESULTS

IN OUR SERIES, THE CLINICAL OUTCOMES AFTER AN IPSILATERAL PTERIONAL APPROACH WITH EXTRADURAL ANTERIOR CLINOIDECTOMY FOR PARACLINOID ANEURYSMS WERE EXCELLENT OR GOOD (GLASGOWS OUTCOME SCALE : GOS 5 or 4) in 87.5% of cases. The microsurgical complications related directly to the extradural anterior clinoidectomy included transient cranial nerve palsy (6), cerebrospinal fluid leak (1), worsened change in vision (1), unplanned ICA occlusion (1), and epidural hematoma (1). Only one of the complications resulted in permanent morbidity (4.2%), and none resulted in death.

CONCLUSION

Although surgical complications are still reported to occur more frequently for the treatment of paraclinoid aneurysms, the permanent morbidity and mortality resulting from a extradural anterior clinoidectomy in our series were lower than previously reported. Precise anatomical knowledge combined with several microsurgical tactics can help to achieve good outcomes with minimal complications.

Relationship between the ophthalmic artery and the dural ring of the internal carotid artery. Clinical article

OBJECT

The ophthalmic artery (OphA) usually arises from the intradural internal carotid artery (ICA), and the extradural origin has also been known. However, the interdural origin is extremely rare. The purpose of this paper was to clarify the origin of the OphA in patients with a paraclinoid aneurysm in the ICA based on intraoperative findings.

METHODS

The authors retrospectively examined 156 patients who underwent direct surgical treatment for 166 paraclinoid aneurysms during a 17-year period. Based on intraoperative findings, 119 ophthalmic arteries were analyzed with respect to their origins.

RESULTS

The OphA originated from the intradural ICA on 102 sides (85.7%), extradural on 9 (7.6%), and interdural on 8 (6.7%). Although the extradural origin might be recognized preoperatively, it was difficult to distinguish the interdural origin of the OphA from the intradural one.

CONCLUSIONS

The incidence of the interdural origin was 6.7% and was not as rare as the authors expected. Neurosurgeons should know the possible existence of the interdural origin of the OphA to section the medial side of the dural ring.

Long-term surgical results with aneurysms involving the ophthalmic segment of the carotid artery

Object

Because of the anatomical complexity of the paraclinoid region, the surgical treatment of aneurysms arising in the C6 segment of the internal carotid artery is extremely challenging. The authors' aim in this study was to describe the extended clinical follow-up and assess the short-term and long-term effectiveness of surgical treatment for these aneurysms, focusing on the clinical outcome and degree of aneurysm occlusion and recurrence.

Methods

The authors retrospectively analyzed the clinical records for patients treated surgically between 1973 and 2004 at the University of Rome, “La Sapienza.” Aneurysms were classified into the following 3 groups according to the site where they arose: the anteromedial, anterior or anterolateral, and posteromedial wall of the C6 segment.

Results

Of the 108 aneurysms in 104 patients treated, 63 (58%) were large or giant. Eighty-eight aneurysms in 84 patients were clipped, 16 underwent a high-flow bypass, 2 were trapped, 1 was wrapped, and 1 was left untreated. The mean follow-up was 126 months; 47 patients had a follow-up of > 10 years. Of the 88 aneurysms that were clipped, 6 (6.8%) had an incomplete occlusion that required an immediate reoperation in 1 case and at 2 years in another. Overall 6 patients (5.8%) had surgery-related permanent complications.

Conclusions

Mortality and morbidity rates depend mainly on the patient's preoperative Hunt and Hess grade subarachnoid hemorrhage, whereas surgical morbidity principally reflects excessive manipulation of the optic nerve or ischemic problems due to excessive temporary trapping undertaken without adequate neuroprotection. In expert hands, surgery (clipping and bypass procedures) is a definitive treatment for C6 aneurysms and has an acceptable complication rate.

Loss of visual evoked potential following temporary occlusion of the superior hypophyseal artery during aneurysm clip placement surgery. Case report

The authors report a case in which a 62-year-old woman with a history of subarachnoid hemorrhage due to a ruptured aneurysm was found to have a de novo paraclinoid aneurysm in the right internal carotid artery during a routine medical examination. Surgical clip placement was performed via a contralateral pterional approach under visual evoked potential (VEP) monitoring. The superior hypophyseal artery (SHA) was found to originate from the aneurysm body. The artery was temporarily occluded prior to application of the clip to the aneurysm neck. The VEP signal was lost 3 minutes after the SHA was occluded, and the potentials gradually recovered 10 minutes after the artery was released. The disappearance of VEP signal was reproducible with SHA occlusion. The clip was applied to the aneurysm body to preserve the origin of the SHA. The patient did not have any deterioration of vision after surgery. Intraoperative VEP monitoring can be used to help determine whether the SHA can be sacrificed safely.

Differentiation between intradural and extradural locations of juxta-dural ring aneurysms by using contrast-enhanced 3-dimensional time-of-flight magnetic resonance angiography

BACKGROUND

Juxta-dural ring aneurysms of the ICA have different clinical outcomes and risks for SAH, which are dependent on their position in the intradural or extradural space. The aim of this study was to reveal the precise location of such aneurysms by using CE-MRA.

METHODS

Contrast-enhanced MRA studies were performed in 21 patients with 24 juxta-dural ring aneurysms. The locations were evaluated by source images of CE-MRA and MPR images. We evaluated the accuracy of preoperative MRI findings by comparing imaging results with intraoperative findings in 7 cases.

RESULTS

The CS was clearly enhanced in the CE-MRA technique, which allowed the precise identification of these aneurysms as intradural or extradural. Intracavernous aneurysms were diagnosed when the greater hyperintensity of the aneurysm was located within the less hyperintense region of the contrast-enhanced CS. Nine of the cases were diagnosed as intradural aneurysms, and 15 aneurysms were noted as extradural based on the findings of CE-MRA. Surgery was performed in 7 cases, which included 4 intradural and 3 extradural aneurysms, and the preoperative MRI findings corresponded with the intraoperative findings in all cases.

CONCLUSION

Contrast-enhanced MRA and MPR are very useful techniques for determining the location of juxta-dural ring aneurysms.

MDCT Angiography for Detection and Quantification of Small Intracranial Arteries: Comparison with Conventional Catheter Angiography

OBJECTIVE

MDCT angiography can serve as an alternative to digital subtraction catheter angiography for the study of large and medium-sized arteries. Our goal was to achieve a better understanding of the capabilities and limitations of both MDCT angiography and digital subtraction angiography in the evaluation of intracranial arteries with an average diameter of 1.5 mm or less.

MATERIALS AND METHODS

A blinded retrospective analysis of the presence and size of nine small cerebral arteries on both 2D and 3D CT angiography (CTA) was conducted with 27 patients who had normal findings at CTA and digital subtraction angiography. Scans of 455 arterial segments obtained with either 4-MDCT or 16-MDCT were examined by two independent blinded reviewers. The sensitivity and specificity of CTA for each vessel were established. A chi-square test was used to determine interoperator reliability.

RESULTS

The smallest arterial size reliably detected with MDCT angiography with our imaging and postprocessing protocol was 0.7 mm versus 0.4 mm for digital subtraction angiography. Interoperator reliability for vessel identification with MDCT angiography was 97% without significant differences in detection rates between 4-MDCT and 16-MDCT. Two-dimensional CTA depicted more than 90% of arteries studied but only 63% of anterior choroidal arteries and 27% of recurrent arteries of Heubner. There were no significant differences in mean arterial sizes measured with 2D CTA versus digital subtraction angiography for six of nine arteries. In six of nine arterial segments with a mean diameter of 1 mm or less, fewer arterial segments were visualized on 3D CTA than on 2D CTA.

CONCLUSION

Except for the recurrent artery of Heubner and the anterior choroidal artery, MDCT angiography depicted 90% or more of all examined small intracranial arteries detected with digital subtraction angiography. The mean sensitivity was 0.91, and the mean specificity was 0.7.

Anatomic features of the intracranial and intracanalicular portions of ophthalmic artery: for the surgical procedures

The intracranial and intracanalicular portions of the ophthalmic artery is suspectible to various diseases and injuries; therefore, knowledge of the microanatomy of the complex bony, dural, vascular, and neural relationships of this segment is necessary for proper diagnosis and preservation of the neurovascular structures during subfrontal, pterional and intracanalicular procedures. The artery was studied in 38 human adult cadaver specimens regarding origin, intracranial and intracanalicular portions for surgical approachs. The ophthalmic artery originated from the intradural portion of the internal carotid artery, except in 5% where the ophthalmic artery originated extradurally. The ophthalmic artery originated from medial of superior wall of internal carotid artery in 73.7%, from the central in 21% and the lateral in 5.3% of the specimens. The diameter of the ophthalmic artery at its origin was 2.25+/-0.3 mm on the right and 2.16+/-0.4 mm on the left. The intracranial and intracanalicular course of the artery was divided into short limb, angle "a", long limb, angle "b" and distal part to the apex of the orbit. Awareness of variations in anatomic structures is paramount importance both for diagnosis and treatment of vascular lesions of the brain.

Microneurosurgical management of carotid-ophthalmic aneurysms

OBJECTIVE

To evaluate the management of carotid-ophthalmic segment aneurysms (COA) with modern microneurosurgical techniques and instruments.

METHOD

Sixty patients with COA undergoing microsurgical clipping between March 1994 and June 2002 in the Department of Neurosurgery, Tiantan Hospital, Beijing, were analyzed retrospectively. Neuroimaging included digital subtraction angiography (DSA), MRI, CT, three-dimensional CT angiography and three-dimensional DSA. From 1998, intraoperative Doppler ultrasound monitoring and endoscope-assisted techniques were used.

RESULT

All aneurysms were completely obliterated without either recurrence or death. The morbidity rate of surgery prior to 1998 was 21.7%, which decreased to 13.7% after 1998 (mean 18.3% for the whole study period).

CONCLUSION

Preoperative planning based on neuroimaging is very valuable. Advances in neuroimaging, endoscope-assisted techniques and intraoperative Doppler ultrasound monitoring are useful to decrease postoperative complications. Microneurosurgical techniques are optimal for the management of COA with ever lessening morbidity.

MRI location of the distal dural ring plane: anatomoradiological study and application to paraclinoid carotid artery aneurysms

The distal dural ring plane (DDRP) separates the intradural from the extradural paraclinoid internal carotid artery. The purpose of this study was to evaluate its position with MR imaging. The protocol used a T2-weighted sequence in two orthogonal planes: diaphragmatic (DIA-P) and carotid (CAR-P). The DDRP passes through four anatomoradiological reference points (RefP). We developed on a cadaveric model a correlation method supported by correlation lines and angles (CA) projecting the RefP toward the DDRP. RefP were correlated to the DDRP in 65-84% of cases in the DIA-P and 60-76% of cases in the CAR-P. CA were identified and correlated to the DDRP, respectively, in 87% and 60% of cases in the DIA-P, and 60% and 51% of cases in the CAR-P (failure often related to a lack of visibility of just one RefP). A higher tissular contrast in living subjects allowed the identification of CA in 90% and 80% of cases, respectively, in the DIA-P and the CAR-P. We propose that CA, when identified, should be considered as an approximation of the inferior radiological limit of the DDRP curve. In difficult angiographical cases, this MRI protocol could help to locate paraclinoid aneurysms on both sides of the cavernous sinus roof.

Ruptured intrasellar superior hypophyseal artery aneurysm presenting with pure subdural haematoma. Case report

SUMMARY

Subdural haemorrhage from a ruptured intracranial aneurysm is a well-known entity when associated with subarachnoid haemorrhage. However, haemorrhage confined only to the subdural space is rare because there are limited anatomical sites where extravasation can be purely subdural. We report the rare case of a patient who suffered pure subdural haematoma after the rupture of a left superior hypophyseal artery aneurysm located within the sella turcica. The patient was treated with endovascular coil embolization of the aneurysm. Angiography immediately after treatment and one month later revealed complete obliteration of the aneurysm. Six months after treatment, the patient remained symptom free.

Surgery for carotid dural ring aneurysms

BACKGROUND

Carotid aneurysms of the paraclinoid segment are usually located in the intradural space, but can infrequently straddle the intra- and extradural space.

CASE DESCRIPTION

We present 2 cases of unruptured carotid dural ring aneurysms with an aneurysmal sac that straddled the distal dural ring. Each paraclinoid aneurysm projected superiorly from the anterior surface of the internal carotid artery with a relatively flattened dome and central indentation on angiography. The aneurysmal domes were circumscribed by the distal dural ring and straddled the intra- and extradural space. After broad opening of the distal dural ring, aneurysms were successfully obliterated by clip application in parallel with the internal carotid artery.

CONCLUSION

These cases underscore the significance of an aneurysmal dome indentation on angiographic images as a reflection of aneurysmal circumscription by the distal dural ring. Aneurysms that straddle the intra- and extradural space may require broad opening of the distal dural ring for adequate control and clipping.

Aneurisma paraclinóideo: técnica cirúrgica e resultados em 51 pacientes

Analisam-se 51 pacientes portadores de 55 aneurismas paraclinóideos (APC) submetidos a tratamento cirúrgico. Em decorrência de tratar-se de procedimento de alta complexidade, descrevemos em pormenor os seus aspectos técnicos. O processo clinóideo anterior foi removido por via extradural após secção da duplicação dural da tenda da fissura orbitária superior e/ou por via intradural. Conseguiu-se exclusão do APC nos 51 pacientes. Em dois casos a clipagem foi parcial e, em três, ocorreu oclusão da ACI. Em 42 (82%) pacientes ocorreu bom resultado; em 5 (10%), incapacidade moderada; em 1 (2%), incapacidade grave e três (6%) faleceram por infarto cerebral. Sete (13,7%) pacientes tiveram lesão adicional do nervo óptico, sendo parcial em 4 (7,7%) e total em 3 (6%).

Unruptured paraclinoid aneurysms: a management strategy

OBJECT

To elucidate an optimal managenent strategy for unruptured paraclinoid aneurysms, the authors retrospectively reviewed their experience in the treatment of 100 patients who underwent 112 procedures for111 paraclinoid aneurysms performed using direct surgery and/or endovascular treatment.

METHODS

Between 1997 and 2002, 111 unruptured paraclinoid aneurysms categorized according to a modified al-Rodhan classification (Group la, 30 anterior wall lesions; Group lb, 25 ventral paraclinoid lesions; Group IL 18 true ophthalmic artery lesions; Group III, 37 carotid cave lesions; and Group IV, one transitional lesion) were treated by direct surgery (35 lesions) and/or endovascular treatment (77 lesions) (one aneurysm was treated by both procedures). In lesions in Groups Ia, Ib, II, and III that were treated by endovascular treatment, complete aneurysm obliteration was achieved in 50, 65, 50, and 78%, respectively, and the combined transient and permanent morbidity rates due to cerebral embolic events were 20, 25, 20, and 13.9%, respectively. Overall, the transient morbidity rate after endovascular treatment was 14.3% and the permanent morbidity rate was 6.5%. Notably, permanent visual deficits caused by retinal embolism occurred after endovascular treatment in two patients with Group II aneurysms. Direct surgery was mainly performed in Groups Ia (20 lesions), Ib (five lesions), and II (eight lesions), with complete neck clip occlusion achieved in 80, 80, and 71.4%, respectively; the transient and permanent morbidity rates associated with aneurysms treated by surgery were 8.6 and 2.9%, respectively.

CONCLUSIONS

Endovascular therapy for superiorly projecting paraclinoid aneurysms (Groups Ia and II) is associated with lower rates of complete obliteration than direct surgery, and with rates of cerebral embolic events comparable to those of endovascular treatment in the other groups. Furthermore, endovascular treatment for Group II aneurysms entails additional risks of retinal embolism. Therefore, direct surgery is recommended for the treatment of paraclinoid aneurysms projecting superiorly. For other groups, especially for Group III, endovascular treatment is the acceptable first line of therapy.

Subclinoid aneurysms

OBJECT

This study was undertaken to analyze the features that define subclinoid aneurysms.

METHODS

Five cases of laterally directed carotid artery (CA) aneurysms adjacent to the anterior clinoid process (ACP) were identified in a series of approximately 1400 surgically treated aneurysms. These cases were selected because the aneurysms had the same features as the only previously described "subclinoid" aneurysm. The angiographic and anatomical features of the five cases were analyzed.

CONCLUSIONS

Subclinoid aneurysms are a unique group of congenital berry aneurysms. They originate from the lateral surface of the CA adjacent to the ACP. They are partially or completely hidden from view at surgery by the ACP and are partially or completely proximal to the distal dural ring of the CA. The proximal neck of these lesions is located at the same level of the CA cut perpendicular to its axis of blood flow as the origin of the ophthalmic artery (OphA), but they do not originate at that or any other branch of the CA. They can only be definitively differentiated from OphA, anterior paraclinoid, and blister-like aneurysms at surgery.

Combined endovascular/neurosurgical therapy of blister-like distal internal carotid aneurysms

OBJECTIVE

To describe a novel therapeutic strategy for the treatment of "blister-like" aneurysms of the distal internal carotid artery (ICA). Direct surgical treatments of these fragile lesions have been associated with generally poor outcomes.

METHODS

Two consecutive patients presenting with acute subarachnoid hemorrhage from "blister-like" aneurysms were treated with preliminary balloon occlusion of the ICA, followed by surgical trapping of the ICA beyond the aneurysm.

RESULTS

The treatment resulted in complete thrombosis of both aneurysms with no clinical complications.

CONCLUSION

This combined endovascular-neurosurgical approach offers a controlled, safer alternative to primary surgical therapy of "blister-like" aneurysms.