Aneurysms of the ophthalmic segment. A clinical and anatomical analysis

Anterior clinoidectomy and opening of the internal auditory canal using an ultrasonic bone curette

OBJECTIVE

During cranial base surgery, use of a high-speed drill for osteotomy has become common. We performed anterior clinoidectomy and opening of the internal auditory canal using an ultrasonic bone curette, and we report the advantages and clinical applications of this method.

DESCRIPTION OF INSTRUMENTATION

The ultrasonic surgical equipment comprises a power supply unit, footswitch, and handpiece (weight, 110 g; diameter, 20 mm; length, 140 mm from tip to angled section). The handpiece tip is 2 mm wide, and the amplitude of longitudinal vibration can be varied from 120 to 365 microm at an ultrasonic frequency of 25 kHz. Cool-controlled irrigation fluid emerges near the tip, through the sheath.

EXPERIENCE AND RESULTS

We performed anterior clinoidectomy in eight cases of paraclinoid aneurysm and opening of the internal auditory canal in six cases of acoustic neuroma without damage to the dura mater or nearby structures such as brain tissue, blood vessels, and cranial nerves. In addition, no damage to the facial nerve or labyrinthine organ resulted from heat or vibration caused by the ultrasonic bone curette.

CONCLUSION

Ultrasonic bone curettage represents safe instrumentation for performance of anterior clinoidectomy and opening of the internal auditory canal without damage to surrounding structures. This technique allows surgeons to perform procedures on deep areas without incurring psychomotor stress.

Combined microsurgical and endovascular management of complex intracranial aneurysms

OBJECTIVE

The disciplines of microneurosurgery and cranial base surgery have reached maturity, and technical advances in the surgical management of aneurysms are limited. Although most aneurysms can be clipped microsurgically or coiled endovascularly, a subset of patients may require a combined approach. A consecutive series of patients with aneurysms in one surgeon's cerebrovascular practice was reviewed retrospectively to analyze strategies for integrating microsurgical and endovascular techniques in the management of complex aneurysms.

METHODS

Between 1997 and 2001, 596 aneurysms in 491 patients were treated microsurgically by the senior author (MTL) at the University of California, San Francisco, and 77 of these patients (96 aneurysms) were managed with a multimodality approach comprising a total of eight different combinations: selective revascularization and aneurysm occlusion (n = 23), endovascular and surgical trapping (n = 1), clipping of the aneurysm after attempted or incomplete coiling (n = 22), coiling after attempted or incomplete clipping (n = 5), clipping of recurrent aneurysm after coiling (n = 6), coiling of recurrent aneurysm after clipping (n = 1), clipping and coiling of multiple remote aneurysms (n = 13), and coiling after previous surgery (n = 6).

RESULTS

A total of 96 aneurysms were treated with combined therapy, of which 43% were large or giant in size and 34% had fusiform or dolichoectatic morphology. Complete angiographic obliteration was achieved in 91 aneurysms (95%). Overall, 66 patients (86%) had good outcomes (Glasgow Outcome Scale score of 4 or 5; mean follow-up, 9 mo). The treatment mortality rate was 9.1% (seven patients), and permanent treatment-associated neurological morbidity rate was 5.2% (four patients).

CONCLUSION

Evolving endovascular technologies need to be integrated into the microsurgical management of aneurysms. Multimodality approaches are best used with complex aneurysms in which conventional therapy with a single modality has failed. Revascularization remains a unique surgical contribution to the overall management of aneurysms with which current endovascular techniques cannot be used. Multimodality management should be considered an elegant addition to the therapeutic armamentarium that, through simplification and increased safety, improves the treatment of complex aneurysms beyond what is achievable by performing clipping or coiling alone.

Two surgical cases of internal carotid-ophthalmic artery aneurysms: special reference to the usefulness of three-dimensional CT angiography

Three-dimensional computerized tomography angiography (3D-CTA) is a noninvasive tool for the diagnosis of cerebral aneurysms. 3D-CTA is helpful in the evaluation of the configuration of aneurysms and their surrounding vessels and anatomical structures. The aim of this study is to assess the usefulness of 3D-CTA for patients with unruptured internal carotid-ophthalmic artery aneurysms. We pre-operatively obtained surgical simulation images using 3D-CTA and 3D reconstruction and then compared them with magnetic resonance angiography (MRA), conventional cerebral angiography and operative findings in the patients. Two patients with unruptured internal carotid-ophthalmic artery aneurysm were selected. These patients underwent direct neck clipping after the optic canal was unroofed through a combined epidural-subdural approach. The cerebral aneurysm was detected by 3D-CTA, MRA and conventional cerebral angiography in each case. Only by 3D-CTA, however, could we easily detect the relationships among the aneurysm neck, ophthalmic artery and optic canal. Based on this information, direct clipping operations were performed safely without any complications. 3D-CTA is an excellent noninvasive diagnostic method not only for detecting cerebral aneurysms, but also for evaluating the relationships between the aneurysms and surrounding structures.

Three-dimensional contrast medium-enhanced computed tomographic cisternography for preoperative evaluation of surgical anatomy of intradural paraclinoid aneurysms of the internal carotid artery: technical note

OBJECTIVE AND IMPORTANCE

Precise preoperative evaluation is especially important when internal carotid artery aneurysms in the paraclinoid region are clipped, because these vascular structures are located in close proximity to various important structures such as the optic nerve and anterior clinoid process. We report a new method for "simultaneously" describing the interrelationships among the aneurysm, internal carotid artery, optic nerve, and bony structures with three-dimensional contrast medium-enhanced computed tomographic (3-D CMECT) cisternography.

METHODS

Informed consent was obtained from the patient. An 8-ml injection of iotrolan (Isovist; Schering, Berlin, Germany) (240 mg I/ml) was administered into the lumbar intrathecal space. A computed tomographic scan of the head was obtained 2 hours later with a multislice Asteion computed tomographic scanner (Toshiba, Inc., Tokyo, Japan). An Alatoview workstation (Silicon Graphics, Mountain View, CA) was used to reconstruct the three-dimensional images.

RESULTS

These images, as generated by 3-D CMECT cisternography, were found to accurately demonstrate the interrelationships of the internal carotid artery, aneurysm, and surrounding structures preoperatively. The findings obtained from these images proved to be quite similar to the intraoperative findings. 3-D CMECT cisternography clarified whether the paraclinoid aneurysm was intradural or extradural.

CONCLUSION

3-D CMECT cisternography was found to provide a useful means for preoperative evaluation of lesions in the paraclinoid area.

Bilateral ophthalmic segment "kissing" aneurysms presenting with subarachnoid hemorrhage--case report

A 31-year-old woman presented with bilateral ophthalmic segment "kissing" aneurysms causing subarachnoid hemorrhage manifesting as sudden severe headache and nausea 3 days before admission. Cerebral angiography demonstrated bilateral internal carotid-superior hypophyseal artery aneurysms, both projecting medially from the medial surface of the internal carotid arteries and appearing to touch each other. Both aneurysms had to be clipped in the same operation, because of uncertainty over which aneurysm had bled. She underwent bilateral frontotemporal craniotomy on the day after admission. Intraoperatively, the two aneurysms were in contact with each other in the suprasellar cistern. Each aneurysm was clipped through the ipsilateral approach without any incident. The patient returned home a month after the operation and has since resumed her previous work. Identification of this rare entity of bilateral ophthalmic segment "kissing" aneurysms is important for surgical planning. Closely situated, bilateral ophthalmic segment aneurysms require a modified surgical strategy for proximal arterial control and the approach to each aneurysm.

De novo formation and rupture of an aneurysm

✓ The authors describe a case of de novo formation and rupture of an aneurysm located at the junction of the left internal carotid artery and the superior hypophyseal artery in a middle-aged woman 2 months after another aneurysm, located on the anterior communicating artery, had been clipped. This case is rare because of the short interval between the last angiographic study performed at the first operation and the diagnosis of the de novo aneurysm; in this case the interval was only 47 days, compared with other cases in the literature in which the intervals were 3 to 34 years. Aneurysms can enlarge considerably in 2 to 4 weeks and can rupture at or soon after their formation. This case provides insight into aneurysm formation and rupture.

Anterior paraclinoid aneurysms

OBJECT

The characteristics of a previously unclassified paraclinoid aneurysm arising from the anterolateral (dorsal) wall of the proximal internal carotid artery were retrospectively analyzed in seven patients (five women and two men) who were treated surgically for an aneurysm in this unusual location.

METHODS

One patient presented with subarachnoid hemorrhage (SAH) caused by rupture of this aneurysm. The lesions were found incidentally (five cases) or during investigation of SAH due to another aneurysm (one case). There was a female predominance in this series; all female patients harbored multiple aneurysms. All patients underwent surgery. Removal of the anterior clinoid process was necessary because the proximal neck of the aneurysm was closely adjacent to the dural ring.

CONCLUSIONS

This special group of aneurysms is very rare, is located exclusively in the intradural space, and carries the risk of SAH. The results of surgical treatment for this aneurysm are quite satisfactory.

Endoscope-assisted clipping of a superior hypophyseal artery aneurysm without removal of the anterior clinoid process. Case report

A 47-year-old man presented with a superior hypophyseal artery aneurysm and an ipsilateral posterior communicating artery aneurysm. Both lesions were successfully clipped without removal of the anterior clinoid process or retraction of the optic nerve by using endoscopic guidance. The endoscope was introduced into the prechiasmatic cistern and provided a clear visual field around the aneurysm that could not be seen via the operating microscope. The endoscope was useful in the identification of the medially projecting lesion and the small perforating branches of the ophthalmic segment of the internal carotid artery. A fenestrated clip could be introduced around the neck of the aneurysm and placed in the best position under endoscopic guidance. Endoscopy-assisted clipping is potentially a very useful procedure for aneurysm surgery.

Radiometric analysis of paraclinoid carotid artery aneurysms

OBJECT

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.

METHODS

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.

CONCLUSIONS

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.

Complete penetration of the optic chiasm by an unruptured aneurysm of the ophthalmic segment: case report

BACKGROUND

It is well known that aneurysms of the ophthalmic segment sometimes elevate the optic nerve or chiasm, and in case of large or giant aneurysms, the optic apparatus can be dramatically thinned. Nonetheless, they rarely penetrate the optic pathway completely. To our knowledge, no previous reports have dealt with the complete penetration of the optic chiasm by unruptured aneurysms of the ophthalmic segment.

CASE DESCRIPTION

A 70-year-old woman presented with visual dysfunction in her left eye that she had experienced for several months. Her left visual acuity had rapidly deteriorated to the level of finger counting and visual field testing demonstrated nasal hemianopsia in the left eye and upper temporal quadrant hemianopsia in the right eye. Left internal carotid angiograms and three-dimensional digital subtraction angiograms showed an aneurysm of the ophthalmic segment projecting superomedially. Intraoperative findings revealed complete penetration of the optic chiasm by the fundus of the aneurysm. The optic pathway adjacent to the dome had become remarkably thin and dark yellow. After clipping was completed, the fundus of the aneurysm was punctured to decompress the optic chiasm. Postoperatively, patient's visual acuity in the left eye gradually recovered, but the visual field deficit persisted after the operation.

CONCLUSION

This rare case demonstrates the potentially aggressive behavior of unruptured aneurysms of the ophthalmic segment. Patients with unruptured aneurysms of the ophthalmic segment who present with visual symptoms should be treated with surgical clipping to decompress the optic pathway as soon as possible.

Architecture of the optic chiasm and the mechanisms that sculpt its development

At the optic chiasm the two optic nerves fuse, and fibers from each eye cross the midline or turn back and remain uncrossed. Having adopted their pathways the fibers separate to form the two optic tracts. Research into the architecture and development of the chiasm has become an area of increasing interest. Many of its mature features are complex and vary between different animal types. It is probable that numerous factors sculpt its development. The separate ganglion cell classes cross the midline at different locations along the length of the chiasm, reflecting their distinct periods of production as the chiasm develops in a caudo-rostral direction. In some mammals, uncrossed axons are mixed with crossed axons in each hemi-chiasm, whereas in others they remain segregated. These configurations are the product of different developmental mechanisms. The morphology of the chiasm changes significantly during development. Neurons, glia, and the signals they produce play a role in pathway selection. In some animals fiber-fiber interactions are also critical, but only where crossed and uncrossed pathways are mixed in each hemi-chiasm. The importance of the temporal dimension in chiasm development is emphasized by the fact that in some animals uncrossed ganglion cells are generated abnormally early in relation to their retinal location. Furthermore, in albinos, where many cells do not exit the cell cycle at normal times, there are systematic chiasmatic abnormalities in ganglion cell projections.

Identification of the carotid artery dural ring by using three-dimensional computerized tomography angiography. Technical note

The carotid artery (CA) dural ring is an important structure in aneurysm surgery of the paraclinoid region. The authors used three-dimensional computerized tomography (3D-CT) angiography to study the CA dural ring. Three-dimensional computerized tomography angiography was performed in patients with cerebral aneurysms and other cerebrovascular diseases. The paraclinoid segment of the internal carotid artery (ICA) was examined by the shaded surface reconstruction method on targeted 3D-CT angiography. The concavity was recognized in the paraclinoid segment of the ICA. The relationship between the concavity and the dural ring was investigated with anatomical studies and surgical findings. In anatomical studies, the concavity in the paraclinoid segment of the ICA on 3D-CT angiography coincided with the level of attachment of the dural ring. Using 3D-CT angiography, it is possible to identify the location of the dural ring in patients being considered for aneurysm surgery.

The surgical management of contralateral anterior circulation intracranial aneurysms

This study reviews the surgical management of contralateral anterior circulation aneurysms in patients with bilateral intracranial aneurysms repaired following a unilateral craniotomy. Between 1993 and 1999, 27 patients had 88 intracranial aneurysms repaired. Eleven patients presented following subarachnoid haemorrhage. Excluding midline aneurysms, 31 anterior circulation aneurysms were contralateral to the craniotomy and all were repaired at the same time that ipsilateral or midline aneurysms were repaired. Morbidity included one death and one case of loss of unilateral vision directly attributable to surgery and two cases of cerebral infarction due to vasospasm. No new neurological deficit or mortality could be directly attributed to the repair of a contralateral aneurysm. The repair of all accessible aneurysms, including those contralateral to the craniotomy, during one session avoids the risk of haemorrhage from incidental or unrecognised ruptured aneurysms (particularly during the aggressive treatment of vasospasm), avoids a second craniotomy, decreases overall hospitalisation and can improve visualisation of carotid-ophthalmic aneurysms.

Skull base techniques for multiple aneurysms in the internal carotid juxta-dural ring region

The aneurysm located in the internal carotid juxta-dural ring region is difficult to surgically obliterate. At surgery, careful drilling of the anterior clinoid process is mandatory, especially when a laterally projecting aneurysm protrudes to or inside the anterior clinoid process.In this paper, treatment procedures using the skull base techniques with intravascular coil embolisation are described by showing a case.

Contralateral pterional approach to a giant internal carotid-ophthalmic artery aneruysm: technical case report

OBJECTIVE AND IMPORTANCE

The contralateral approach to internal carotid-ophthalmic artery aneurysms has been used in selected cases but has rarely been described for a giant internal carotid artery aneurysm. We report a case of giant aneurysm that was successfully clipped via the contralateral pterional approach.

CLINICAL PRESENTATION

A 69-year-old woman was found to have two aneurysms: a small aneurysm at the left internal carotid-posterior communicating artery and a giant aneurysm at the right internal carotid-ophthalmic artery.

INTERVENTION

A direct clipping operation was performed via the left pterional approach. After the small left internal carotid artery aneurysm was clipped, the contralateral giant aneurysm was further exposed and successfully clipped by use of the same approach via the prechiasmatic space.

CONCLUSION

The contralateral pterional approach can be applied even for a giant aneurysm of the carotid-ophthalmic artery aneurysm when the neck of the aneurysm is small and when there is a space between the anterior wall of the aneurysm and the tuberculum sellae. Furthermore, such a giant aneurysm can be clipped more easily and safely via the contralateral approach without compromising visual functions. To our knowledge, this is the first reported case of a giant internal carotid-ophthalmic artery aneurysm approached contralaterally. The feasibility of this approach can be assessed preoperatively by three-dimensional computed tomographic angiography as well as by conventional cerebral angiography.

Surgical repair of clinoidal segment carotid artery aneurysms unsuitable for endovascular treatment

OBJECTIVE

Clinoidal segment carotid artery aneurysms are surgically challenging lesions. The aneurysm neck originates proximal to the distal dural ring, and the aneurysms typically are larger. Therefore, endovascular techniques are often considered to be the primary treatment option. Treatment techniques and results for 40 clinoidal segment carotid artery aneurysms that were considered unsuitable for contemporary endovascular intervention are analyzed in this report.

METHODS

Forty aneurysms in 33 female and 3 male patients were treated surgically. Fifteen patients had bilateral aneurysms; of these patients, four underwent bilateral craniotomies. Twenty-seven aneurysms were 10 to 14 mm in size, eight were 15 to 24 mm, and five were more than 25 mm. The most common presentation was visual loss, which occurred in 13 patients. Seven patients presented with subarachnoid hemorrhage.

RESULTS

Thirty-seven aneurysms were directly repaired with clipping, two were trapped with bypass, and one was trapped without bypass. The complication rate was 10%, with one major stroke, two minor strokes, and one successfully treated brain abscess.

CONCLUSION

Surgical treatment of clinoidal segment carotid artery aneurysms can produce acceptable outcomes. Specific preoperative and intraoperative techniques facilitate improved surgical results for aneurysms that are not treatable with contemporary endovascular techniques.

Results after surgical and endovascular treatment of paraclinoid aneurysms by a combined neurovascular team

OBJECTIVE

Advances in surgical and endovascular techniques have improved treatment for paraclinoid aneurysms. A combined surgical and endovascular team can formulate individualized treatment strategies for patients with paraclinoid aneurysms. Patients who are considered to be at high surgical risk can be treated endovascularly to minimize morbidity. We reviewed the clinical and radiographic outcomes of 238 paraclinoid aneurysms treated by our combined surgical and endovascular unit.

METHODS

From 1991 to 1999, the neurovascular team treated 238 paraclinoid aneurysms in 216 patients at the Massachusetts General Hospital. The modality of treatment for each aneurysm was chosen based on anatomic and clinical risk factors, with endovascular treatment offered to patients considered to have higher surgical risks. One hundred eighty aneurysms were treated by direct surgery, 57 were treated by endovascular occlusion, and one was treated by surgical extracranial-intracranial bypass and endovascular internal carotid artery balloon occlusion. Locations were transitional, 12 (5%); carotid cave, 11 (5%); ophthalmic, 131 (55%); posterior carotid wall, 38 (16%); and superior hypophyseal 46 (19%). Lesions contained completely within the cavernous sinus were excluded from this analysis.

RESULTS

Using the Glasgow Outcome Scale (GOS), overall clinical outcomes were excellent or good (GOS 5 or 4), 86%; fair (GOS 3), 7%; poor (GOS 2), 4%; and death (GOS 1), 3%. Among the surgically treated patients, 90% experienced excellent or good outcomes (GOS 5 or 4), 6% had fair outcomes (GOS 3), 2% had poor outcomes (GOS 2), and 3% died (GOS 1). Among the endovascularly treated patients, 74% had excellent or good outcomes (GOS 5 or 4), 12% had fair outcomes (GOS 3), 10% had poor outcomes (GOS 2), and 4% died (GOS 1). The overall major and minor complication rate from surgery was 29%, with a 6% surgery-related permanent morbidity rate and a mortality rate of 0%. The overall major and minor complication rate from endovascular treatment was 21%, with a 3% endovascular-related permanent morbidity rate and a 2% mortality rate. Visual outcomes for patients who presented with visual symptoms were as follows: improved, 69%; no change, 25%; worsened, 6%; and new visual deficits, 3%. In general, angiographic efficacy was lower in the endovascular treatment group.

CONCLUSION

A combined team approach of direct surgery and endovascular coiling can lead to good outcomes in the treatment for paraclinoid aneurysms, including high-risk lesions that might not have been treated in previous surgical series.

Parameters for contralateral approach to ophthalmic segment aneurysms of the internal carotid artery

OBJECTIVE

This study was undertaken to define more accurately the feasibility and indications of the contralateral pterional approach to ophthalmic segment aneurysms of the internal carotid artery (ICA).

METHODS

Between 1995 and 1999, 46 patients with ophthalmic segment aneurysms of the ICA were surgically treated in our institution. Eleven of the 46 aneurysms were operated using the contralateral pterional approach. All aneurysms were successfully clipped without complications; three patients required bone resection around the aneurysm neck. We studied the 11 patients who were treated with the contralateral approach by defining six parameters to assess the feasibility of the approach and to predict the necessity for bone resection: 1) Parameter A, the distance between the anterior aspect of the optic chiasm and the limbus sphenoidale; 2) Parameter B, the distance between the bilateral optic nerves at the entrance to the optic canal; 3) Parameter C, the interrelation of the optic nerve and the ICA, expressed as a/b in which a is the length from the midline to the optic nerve and b is the length from the midline to the ICA; 4) Parameter D, the size of the aneurysm neck; 5) Parameter E, the direction of the aneurysm from the ICA wall on the anteroposterior angiogram; and 6) Parameter F, the distance from the medial side of the estimated distal dural ring to the proximal aneurysm neck on the lateral angiogram.

RESULTS

Parameters A to F were 8.8 mm (range, 5.4-11.1 mm), 14.5 mm (range, 10.4-22.2 mm), 0.9 mm (range, 0.6-1.3 mm), and 3.0 mm (range, 2.3-4.7 mm), 5 to 160 degrees, and 1.3 mm (range, 0.3-2.4 mm), respectively. All patients had excellent operative outcomes without visual dysfunction. Three patients required drilling of the bone around the optic canal on the craniotomy side; bone drilling was not required when Parameter E was between 30 and 160 degrees and Parameter F was more than 1 mm.

CONCLUSION

Parameters A to D are important for assessing the feasibility of the contralateral approach to ICA-ophthalmic segment aneurysms, and Parameters E and F are most useful for calculating the difficulty of this approach.

Endovascular treatment of paraclinoid aneurysms

BACKGROUND

Paraclinoid aneurysms include those that are distal to the cavernous segment of the internal carotid artery and proximal to the posterior communicating artery. The purpose of this study was to review our experience with the endovascular treatment of this group of aneurysms, which are difficult to treat surgically.

METHODS

Between June 1994 and April 1999, 66 patients (56 female, 10 male) with a mean age of 50.1 years (range 13-75, median 51) underwent endovascular treatment for 71 paraclinoid aneurysms. The mean size of the dome was 8.9 mm (range 3-25 mm, median 7) and the of neck was 3.8 mm (range 1.4-8 mm, median 4). Thirteen patients presented with acute subarachnoid hemorrhage, and 4 with previous subarachnoid hemorrhage. Six aneurysms produced mass effect with visual symptoms, 4 presented with transient ischemic attacks, and 44 were incidental. Nine patients had had previous unsuccessful surgery. All procedures were performed under general anesthesia and with systemic heparinization.

RESULTS

Ninety endovascular procedures were performed on 71 aneurysms: GDC coiling in 78 (including 45 with the remodeling technique), permanent balloon occlusion in 9, and 3 had both GDC coiling and permanent balloon occlusion. In ten aneurysms it was not possible to place coils in the lumen of the aneurysm with the available technology and balloon occlusion was not indicated. Five of these were treated surgically and 5 remain untreated. All patients had immediate post procedure angiography. Of the 61 aneurysms that were treated, 46 (75%) have angiographic follow-up of 6 months or more. Morphological outcome following endovascular therapy for 61 aneurysms at last available follow-up showed > 95% occlusion in 52/61 (85.2%) and <95% in 9/61 (14.8%). Eight patients required surgery, 2 for partial coiling, 2 for refilling of a neck remnant, 2 for persistent mass effect and 2 for coil protrusion. In the 90 procedures performed, 2 (2.2%) patients had major permanent deficits (1 monocular blindness, 1 hemiparesis), 1 (1.1%) had a minor visual field cut, and 2 (2.2%) patients died from major embolic events.

CONCLUSION

Properly selected paraclinoid aneurysms can be successfully treated by endovascular technology. The morbidity and mortality rate of the endovascular approach in our experience is equal to or better than the published surgical series of similar aneurysms. We recommend that the endovascular approach be given primary consideration in the treatment of paraclinoid aneurysms.

Rupture of a large ophthalmic segment saccular aneurysm associated with closed head injury: case report

OBJECTIVE AND IMPORTANCE

Although each year approximately 30,000 to 50,000 cases of subarachnoid hemorrhage in the United States are caused by the rupture of intracranial saccular aneurysms, there is little information in the literature documenting the association of aneurysmal rupture with closed head injury.

CLINICAL PRESENTATION

A 61-year-old woman presented after a motor vehicle accident with multiple injuries, including a severe closed head injury. Computed tomography revealed a diffuse basal subarachnoid hemorrhage. Angiography revealed the source as a large aneurysm arising from the ophthalmic segment of the left carotid artery.

INTERVENTION

After the patient was stabilized for her multiple injuries, she underwent craniotomy and clipping of the aneurysm. She recovered without developing new neurological deficits.

CONCLUSION

Although the association of head trauma and aneurysmal subarachnoid hemorrhage is rare, the presence of significant basal subarachnoid blood on a computed tomographic scan should alert the physician to the possibility of a ruptured aneurysm.

Balloon-assist technique for endovascular coil embolization of geometrically difficult intracranial aneurysms

OBJECTIVE

The balloon-assist or neck-remodeling technique is an adjunctive method devised for the endovascular coil embolization of aneurysms characterized by a wide neck or unfavorable geometric features. Since its initial description, there have been few data to corroborate its utility, efficacy, and safety in aneurysm embolization.

METHODS

Twenty patients (19 female patients and 1 male patient) with 22 aneurysms (19 unruptured aneurysms and 3 ruptured aneurysms) underwent balloon-assisted coil embolization. The balloon-assist technique was performed in the same treatment session after conventional coil embolization had failed in 55% of cases (12 of 22 cases) and was the primary treatment in 45% of cases. The majority of aneurysms were located in the supraclinoid carotid artery (13 paraophthalmic and 3 superior hypophyseal aneurysms). The mean angiographic measurements included a fundus of 8.7 +/- 3.7 mm, a neck of 5.3 +/- 2.2 mm, and a comparatively unfavorable fundus/neck ratio of 1.33 +/- 0.23.

RESULTS

Technical success was achieved in 77% of cases (17 of 22). The rate of aneurysm obliteration at the end of the procedures was 97 +/- 3.8%. Angiographic follow-up data (mean follow-up period, 10.3 mo) obtained for 89% of the treated aneurysms (15 of 17) confirmed stable mean occlusion of 97.8 +/- 3.8%. Technical complications included two cases of asymptomatic distal vessel thromboembolism, which resolved angiographically within 24 hours, and one case of intraprocedural rupture of an arteriovenous malformation-related feeder artery aneurysm, which resulted in no neurological deficits and required no further treatment (transient complication rate, 13.6%; 3 of 22 cases). There were no deaths and no procedure-related 30-day or permanent morbidity.

CONCLUSION

The balloon-assist method of coil embolization is characterized by promising intermediate-term angiographic and clinical outcomes and acceptable morbidity and mortality rates. Although this adjunctive method requires the use of an additional microcatheter and consequently involves a higher level of technical complexity, it extends the range of aneurysms that can be successfully treated with electrolytically detachable coils via an endovascular approach.

Contralateral approach to junctional C2-C3 and proximal C4 aneurysms of the internal carotid artery: microsurgical anatomic study

OBJECTIVE

To evaluate a contralateral approach to aneurysms located in the internal carotid artery cave and proximal C4 segments.

METHODS

In six adult cadaveric head sides, proposed aneurysms in the carotid cave or proximal C4 segments were approached via contralateral craniotomies. We summarize the approach in the following steps: 1) frontotemporal orbital craniotomy, 2) drilling of the lateral sphenoid wing and opening of the dura along the frontotemporal base, 3) drilling of the planum sphenoidale and the tuberculum sellae more extensively toward the aneurysm side and opening of the sphenoid sinus, 4) drilling of the medial part of the anterior clinoid process on the side of the aneurysm and removal of the superior, medial, and inferior walls of the optic canal, 5) opening of the optic sleeve, and 6) opening of the space between the medial wall of the internal carotid artery C2-C3 segments and the lateral edge of the pituitary gland.

RESULTS

The contralateral approach to expose the opposite internal carotid artery cave and proximal C4 segments provided excellent views of the region, without mobilization or retraction of either the optic nerve or the carotid artery.

CONCLUSION

We recommend that this approach be used only for selected aneurysms, which are small and directed medially, anteriorly, or inferiorly, in the defined locations.

Efficacy of targeted CT angiography in evaluation of intracranial internal carotid artery disease

RATIONALE AND OBJECTIVES

This study evaluated the efficacy of targeted computed tomographic (CT) angiography in the diagnosis of intracranial internal carotid artery (ICA) disease and compared the results of routine and targeted CT angiography.

MATERIALS AND METHODS

Fifty-four patients (24 male and 30 female patients aged 2 months to 87 years) were examined with CT angiography. Digital subtraction angiography (DSA) was performed in 42. CT angiograms were reconstructed with the maximum-intensity projection (MIP) algorithm. Targeted CT angiography was performed by individually reconstructing a single ICA territory. Each ICA was divided into four segments, and findings of routine MIP CT angiography, routine MIP plus targeted CT angiography, and DSA were reviewed independently by two neuroradiologists for vascular lesions involving each segment. Routine and targeted CT angiograms were also evaluated to determine how well both ICAs were visualized.

RESULTS

Routine CT angiography was rated good or excellent for ICA visualization in 64% of cases, compared with 81% for targeted CT angiography (P = .0005). The overall agreement between routine CT angiography and DSA and between routine plus targeted CT angiography and DSA was 92% and 94%, respectively. There was no statistically significant difference between the percentages of vascular lesions detected with routine CT angiography alone and with routine plus targeted CT angiography. Both methods tended to show false-positive findings of steno-occlusive disease, but targeted CT angiography showed details of aneurysms and stenotic lesions that were easily overlooked with routine CT angiography alone.

CONCLUSION

Routine plus targeted CT angiography, while providing superior image quality, did not have much clinical effect; further assessment may be needed.

Subarachnoid haemorrhage following rupture of an ophthalmic artery aneurysm presenting as traumatic brain injury

Head trauma may provoke subarachnoid haemorrhage. The question sometimes arises whether in patients with trauma and subarachnoid haemorrhage the latter is of traumatic or aneurysmal origin. We present a 49-year-old patient who fell from a truck, struck his head and was unconscious immediately. On the brain computed tomography (CT) scan subarachnoid haemorrhage was present, initially diagnosed as of traumatic origin. Four-vessel angiography revealed rupture of a left ophthalmic artery aneurysm. We review the literature and give recommendations for angiography in patients with trauma and subarachnoid haemorrhage.

Microsurgical anatomic features and nomenclature of the paraclinoid region

OBJECTIVE

We describe the detailed microsurgical anatomic features of the clinoid (C5) segment of the internal carotid artery (ICA) and surrounding structures, clarify the anatomic relationships of structures in this region, and emphasize the clinical relevance of these observations. Furthermore, because the nomenclature of the paraclinoid region is confusing and lacks standardization, this report provides a glossary of terms that are commonly used to descibe the anatomic features of the paraclinoid region.

METHODS

The region surrounding the anterior clinoid process was observed in 70 specimens from 35 formalin-fixed cadaveric heads. Detailed microanatomic dissections were performed in 10 specimens. Histological sections of this region were obtained from the formalin-fixed cadaveric specimens.

RESULTS

The clinoid segment of the ICA is the portion that abuts the clinoid process. This portion of the ICA can be directly observed only after removal of the clinoid process. The dura of the cavernous sinus roof separates to enclose the clinoid process. The clinoid segment of the ICA exists only where this separation of dural layers is present. Because the clinoid process does not completely enclose the ICA in most cases, the clinoid segment is shaped more like a wedge than a cylinder. The outer layer of the dura (dura propria) is a thick membrane that fuses with the adventitia of the ICA to form a competent ring that separates the intradural ICA from the extradural ICA. The thin inner membranous layer of the dura loosely surrounds the ICA throughout the entire length of its clinoid segment. The most proximal aspect of this membrane defines the proximal dural ring. The proximal ring is incompetent and admits a variable number of veins from the cavernous plexus that accompany the ICA throughout its clinoid segment.

CONCLUSION

The narrow space between the inner dural layer and the clinoid ICA is continuous with the cavernous sinus via an incompetent proximal dural ring. This space between the clinoid ICA and the inner dural layer contains a variable number of veins that directly communicate with the cavernous plexus. Given the inconstancy of the venous plexus surrounding the clinoid ICA, we think that categorical labeling of the clinoid ICA as intracavernous or extracavernous cannot be justified.

A combined transorbital-transclinoid and transsylvian approach to carotid-ophthalmic aneurysms without retraction of the brain

A series of 138 patients with 143 carotid-ophthalmic aneurysms (COAs) have been treated by direct surgical approach over the past 15 years. In 5 cases the COAs were bilateral and in 15 cases either one or more aneurysms were associated with a COA. Of the 143 COAs, 87 were small, 41 large and 15 were giant. Seventy-four COAs bled, while 69 were diagnosed either incidentally or else manifested themselves through neurological deficits resulting from compression of the adjacent structures by the aneurysms. Visual deficits were diagnosed in all the patients with large/giant COAs and in 27 patients with small COAs. Of the whole series of patients operated on for COAs, 2 died after surgery. Two patients had endocrinological deficits, 2 had hemiparesis, 36 had the same visual deficits as prior to surgery, whereas in 47 patients the visual function improved. Of all the 138 patients, 96 remained without neurological deficits, and the 36 patients with the same visual deficits as preoperatively also showed no neurological deficits after surgery and hence they were able to resume their previous way of life. Vasospasm did not occur in patients with COA(s) only, but was observed in 6 out of 15 patients with multiple aneurysms where subarachnoid hemorrhage (SAH) had occurred due to a rupture of an aneurysm other than the COA. There has been a major change in the surgical approach to COAs, from the classical pterional intradural approach to the transorbital-transclinoid and transsylvian approach which is described in this report. The latter approach provides ample space for proximal and distal control of the internal carotid artery (ICA) and makes it possible to deal with demanding large/giant COAs safely. In the series presented, there was no case of premature rupture of the aneurysm. Moreover, since we started using the described approach to COAs, retraction of the brain has not been necessary, regardless of the size of the aneurysm.

Clinoid and paraclinoid aneurysms: surgical anatomy, operative techniques, and outcome

BACKGROUND

Paraclinoid or ophthalmic segment aneurysms arise from the internal carotid artery (ICA) between the roof of the cavernous sinus and the origin of the posterior communicating artery. Clinoid aneurysms arise between the proximal and distal carotid dural rings. The complex anatomy of clinoid and paraclinoid ICA aneurysms often makes them difficult to treat by microsurgery. The natural history of these aneurysms varies, based on their location and anatomic relationships. Accurate preoperative assessment of the origin of these aneurysms is therefore a critical aspect of their management.

METHODS

The authors reviewed 35 clinoid and paraclinoid ICA aneurysms operated in 28 patients and classify them according to their anatomic location and angiographic pattern. The operative techniques, surgical outcomes, and indications for surgery are reviewed.

RESULTS

Based on surgical anatomy and angiographic patterns, the aneurysms were classified into two categories: clinoid segment and paraclinoid (ophthalmic) segment. The clinoid segment aneurysms consisted of medial, lateral and anterior varieties. The paraclinoid aneurysms could be classified topographically into medial, posterior and anterior varieties, or based on the artery of origin into ophthalmic, superior, hypophyseal, and posterior paraclinoid aneurysms. Ophthalmic aneurysms were most common (40%), followed by posterior ICA wall aneurysms (29%), superior hypophyseal aneurysms (14%), and clinoid aneurysms (17%). Twenty patients (71%) had single aneurysms. Of the remaining eight, six had bilateral aneurysms and two had unilateral multiple aneurysms. Of the 35 aneurysms, 32 were clipped satisfactorily, as confirmed by intraoperative or postoperative angiography. One small broad-based aneurysm was wrapped, and two others were treated by trapping and bypass techniques. Three patients who had bilateral aneurysms underwent successful clipping of four contralateral, left-sided aneurysms via a right frontotemporal, transorbital approach. On follow-up (mean, 39 months), 25 patients were in excellent condition (returned to their prior occupation), two were in good condition (independent, but not working), and one died postoperatively of vasospasm.

CONCLUSION

Our increased knowledge of anatomy and refinements in operative techniques have greatly improved the surgical treatment of clinoid and paraclinoid aneurysms.

"Kissing" bilateral large carotid-ophthalmic aneurysms. A case report

A case of unruptured bilateral large carotid-ophthalmic aneurysms, which appear to be adjoining and "kissing" each other when visualized by three-dimensional computed tomographic angiography (3-D CTA), is reported. Although bilateral carotid-ophthalmic aneurysms are not rare, bilateral large ones are quite rare, and direct imaging of "kissing aneurysms" of this portion has not been reported. Since 3-D CTA is becoming a useful tool for the diagnosis of cerebral aneurysms, we propose that these and similar bilateral large carotid-ophthalmic aneurysms are good candidates for the term "kissing aneurysms".

A combined microsurgical skull-base and endovascular approach to giant and large paraclinoid aneurysms

BACKGROUND

The treatment of giant and large paraclinoid aneurysms remains challenging. To improve exposure, facilitate the dissection of aneurysms, assure vascular control, reduce brain retraction and temporary occlusion time, enable simultaneous treatment of associated lesions, and achieve more successful treatment of "difficult" (atherosclerotic and calcified) aneurysms, we combined the skull-base approach with endovascular balloon occlusion of the internal carotid artery (ICA) and suction decompression of the aneurysm.

METHODS

Sixteen female patients were treated, eight with giant aneurysms and eight with large aneurysms. Eight aneurysms occurred on the right side and eight on the left. Eight patients had an additional aneurysm; five were clipped during the same procedure. Three patients had infundibular arterial dilation. One patient had an associated hemangioma of the ipsilateral cavernous sinus. The cranio-orbital-zygomatic approach was used for all patients. The anterior clinoid was drilled, and the optic nerve was decompressed, dissected, and mobilized. Transfemoral temporary balloon occlusion of the ICA in the neck was followed by placement of a temporary clip proximal to the posterior communicating artery. Suction decompression was then applied. All aneurysms were then successfully clipped, except one that had a calcified neck and wall that could not be collapsed. Intraoperative angiography performed in 13 of 15 patients with clipped aneurysms confirmed obliteration of the aneurysm and patency of the blood vessels.

RESULTS

Postoperative results were good in 14 patients. One patient had right-sided hemiplegia and expressive aphasia, which improved after rehabilitation. One patient with an additional basilar tip aneurysm clipped simultaneously died on the fifth postoperative day because of intraventricular hemorrhage. The origin of bleeding could not be determined on autopsy. Surgical difficulties and morbidity stemmed mainly from a severely calcified or atherosclerotic aneurysmal neck.

CONCLUSION

The combination of skull-base approaches and endovascular balloon occlusion coupled with suction decompression is a successful option for the treatment of these challenging aneurysms.

Endosaccular embolization for internal carotid artery aneurysms at the c3 portion

SUMMARY

Direct surgery for the aneurysms at the C3 portion of the internal carotid artery (ICA) requires relatively complicated procedures. We present three patients with this aneurysm who underwent endovascular embolization. The remodelling technique was utilized in two of these patients with unruptured aneurysms. Sufficient obliteration was achieved in every case. Endovascular embolization may be an important alternative for ICA C3 aneurysms.

Surgical anatomy of the juxta-dural ring area

OBJECT

The authors report on the surgical anatomy of the juxta-dural ring area of the internal carotid artery to add to the information available about this important structure.

METHODS

Twenty sides of cadaver specimens were used in this study. The plane of the dural ring was found to incline in the posteromedial direction. Medial inclination was measured at 21.8 degrees on average against the horizontal line in the anteroposterior view on radiographic studies. Posterior inclination was measured at 20.3 degrees against the planum sphenoidale in the lateral projection, and the medial edge of the dural ring was located 0.4 mm above the tuberculum sellae in the same projection. The lateral edge of the dural ring was located 1.4 mm below the superior border of the anterior clinoid process. The carotid cave was situated at the medial or posteromedial aspect of the dural ring; however, two of the 20 specimens showed no cave formation. The carotid cave contained the subarachnoid space in 13 sides, the arachnoid membrane only in three sides, and the extraarachnoid space in two sides. The authors propose that the marker of the medial side of the dural ring, which is more proximal than the lateral, is the tuberculum sellae in the lateral view on radiographic studies. In the medial aspect of the dural ring the intradural space can be situated below the level of the tuberculum sellae because of the existence of the carotid cave.

CONCLUSIONS

An aneurysm arising from the medial side of the juxta-dural ring area even below the tuberculum sellae is a potential cause of subarachnoid hemorrhage.

Unusual aneurysms of the distal internal carotid artery

BACKGROUND

Supraclinoid carotid aneurysms have traditionally been classified according to their relation to the major carotid branches, but considerable variation exists with respect to site of origin, projection, and relationship to the skull base. Distal internal carotid aneurysms with a superior or medial projection are uncommon vascular lesions, with an unusually high incidence of operative complications.

METHODS

Surgical experience with five patients suffering from subarachnoid hemorrhage due to ruptured aneurysms of the dorsomedial wall of the distal internal carotid artery is presented, with emphasis on their angiographic appearance, anatomical features, and operative management.

RESULTS

All five patients underwent surgical clipping. Intra-operative rupture occurred in two cases, with avulsion of the aneurysm from the internal carotid artery in both. A third patient experienced recurrent subarachnoid hemorrhage three days after uneventful surgery, due to the clip shearing off of the parent vessel.

CONCLUSIONS

Distal internal carotid aneurysms do not conform to the usual principles of aneurysm formation and are unique in their dorsomedial location unrelated to an arterial bifurcation. Although their anatomy is straightforward and exposure is not restricted by bone or dural structures of the skull base, they possess extremely fragile necks which make surgical management particularly hazardous.

The ophthalmology of intracranial vascular abnormalities

PURPOSE

To provide a practical review of the ophthalmologic manifestations of intracranial vascular abnormalities.

METHODS

We reviewed ocular manifestations of the most common intracranial vascular abnormalities: intracranial aneurysms, carotid-cavernous fistulas, arteriovenous malformations, and cavernous malformations.

RESULTS

Unruptured aneurysms can compress the third cranial nerve and the anterior visual pathways. Ruptured aneurysms and subarachnoid hemorrhage can result in Terson syndrome and papilledema. Direct and indirect carotid-cavernous fistulas most commonly cause the classic triad of proptosis, conjunctival chemosis, and cranial bruit but can masquerade as chronic conjunctivitis. Arteriovenous malformations, with or without hemorrhage, may compress portions of the retrochiasmal pathways, causing visual field loss. Cavernous malformations, when in the brainstem, commonly cause abnormalities of supranuclear, nuclear, and fascicular ocular motility.

CONCLUSIONS

The ophthalmologist may be the first physician to encounter clinical manifestations of intracranial vascular abnormalities that may herald devastating neurologic complications. Prompt diagnosis facilitates appropriate management and therapy.

Microsurgical anatomy of the dural collar (carotid collar) and rings around the clinoid segment of the internal carotid artery

OBJECTIVE

To examine the relationship of the clinoid segment of the internal carotid artery to the structures in the roof of the cavernous sinus and to determine whether this segment is neither intradural nor intracavernous, as recently proposed.

METHODS

The region of the roof of the cavernous sinus was dissected and examined using 3 to 40x magnification and micro-operative techniques.

RESULTS

The clinoid segment was located within a collar formed by the dura lining the medial surface of the anterior clinoid process, the posterior surface of the optic strut, and the upper part of the carotid sulcus. The clinoid segment and the collar were defined above by the upper ring formed by the dura extending medially from the upper surface of the anterior clinoid process to surround the artery and below by the lower ring formed by the dura extending medially from the lower surface of the anterior clinoid process. The upper ring was adherent to the wall of the artery, but the lower dural ring was separated from the lower margin of the clinoid segment by a narrow space that admitted venous tributaries of the cavernous sinus, called the clinoid venous plexus. This venous plexus narrowed as the upper ring was approached and became wider at the lower ring, where the plexus communicated with the venous channels of the cavernous sinus. The upper and lower dural rings were best defined along the lateral and anterior margins of the artery, were less distinct medially, and disappeared posteriorly, where the dura forming the upper and lower rings came together.

CONCLUSION

The clinoid segment is intracavernous, being located within a collar of dura in which venous tributaries of the cavernous sinus course. The implications of these findings for surgery are reviewed.

Open surgery of giant paraclinoid aneurysms improved by intraoperative angiography and endovascular retrograde suction decompression

In three consecutive cases of giant left sided paraclinoid aneurysms we employed an endovascular retrograde suction decompression technique in combination with intra-operative angiography. A double-lumen balloon catheter was placed in the left internal carotid artery by the transfemoral route. After balloon inflation and placement of a temporary clip distal to the aneurysm blood was aspirated and the aneurysm collapsed. Thus further dissection of the aneurysm could easily be achieved and clips could be placed. Afterwards real-time digital subtraction angiography was performed. Intra-operative angiography led to clip repositioning in all cases either due to a clip induced stenosis of the parent vessel, or because of incomplete aneurysm obliteration. Afterwards successful clipping could be confirmed in all cases. Outcome was excellent in one case, good in the other. The third case, extremely complicated by an accompanying craniopharyngioma, showed a satisfactory outcome, but presented new neurological deficits.

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.

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.