Application of anterior clinoid grinding in sellar region tumors and ophthalmic/superior clinoid process aneurysms of internal carotid artery / 中国医师进修杂志

Objective:To evaluate the clinical effect of anterior clinoid process grinding in the treatment of ophthalmic / superior clinoid process aneurysms and sellar tumors.Methods:The clinical data of 16 patients who underwent anterior clinoid process grinding in Sanbo Brain Hospital, Capital Medical University from January 2015 to July 2021 were analyzed retrospectively. There were 1 patient with recurrent craniopharyngioma, 1 patient with recurrent pituitary adenoma, 13 patients with aneurysms, and 1 patient with suprasellar granulosa cell tumor combined with ophthalmic aneurysm of right internal carotid artery. The Modified Rankin Scale (mRS) score was used to evaluate the situation at discharge and in the medium-and-long term.Results:Sixteen patients underwent anterior clinoidprocess grinding. At discharge and the latest follow-up, the mRS scores of the patients were 0-2. A total of 15 aneurysms were treated, and there were no symptoms of visual loss or visual field defect after operation. No cerebrospinal fluid leakage occurred in all patients.Conclusions:The grinding of anterior clinoid process can effectively and fully stretch the optic nerve and internal carotid artery, and can observe the tumor neck at the lower end of pituitary stalk and the ocular segment/superior clinoid process of internal carotid artery under direct vision. It is one of the important auxiliary methods for the treatment of sellar lesions.

Impact of Anterior Clinoid Process Pneumatization on Adjacent Anatomical Structures

The Anterior clinoid process is closely related to many important anatomical structures including vessels, nerves, and paranasal sinuses. In the majority of cases, this process is osseous, but its pneumatization has been recorded as an anatomic variant. Coronal CT scans of the head region that were done for thirty-seven patients at Tanta University hospitals were collected to be used in teaching radiological anatomy for medical students. During their routine investigation, a case of a female aged 21 years showed bilateral pneumatization of the anterior clinoid processes associated with some variants of the adjacent anatomical structures. These findings were discussed on anatomical basis with referral to their possible clinical implications. If a surgical removal of the anterior clinoid process is recommended, a comprehensive knowledge of its anatomy, pneumatization, and associated regional anatomic variants is crucial for neurosurgeons to avoid risky complications.

Tuberculum sellae meningioma: Is there an ideal approach? / Meningioma de tubérculo selar: há uma abordagem cirúrgica ideal?

BACKGROUND: Tuberculum sellae meningiomas is a serious challenge for neurosurgeons. It accounts for up to 10% of all intracranial meningiomas. The difficulty in surgically excising a Tuberculum sellae meningioma comes from its anatomical relationship to the optic nerves and chiasm and to the anterior cerebral and internal carotid arteries and their perforators. The authors discuss the main approaches and the complications based on their experience in comparison to previously reported data. METHODS: We report our personal case series of 38 patients with Tuberculum sellae meningiomas; 36 patients under went craniotomy for tumor resection (12 bifrontal, 12 pterional, 6 supraciliary, 4 unilateral frontals, and 2fronto-orbito-zygomatic); in two patients, the excision was performed through an endoscopic endonasal approach. The Simpson grade of meningioma resection as wellhe non-visual morbidity and the mortality rates were analyzed. RESULTS: Thirty-one patients had Simpson grades 1 and 2 excisions, while seven had Simpson grade 4 excisions. The overall rate of non-visual morbidity was 13.15% (5 of 38 patients) and mortality was 5.3% (2 of 38). CONCLUSION: The primary symptom leading to the diagnosis of a Tuberculum sellae meningioma is visual compromise and the main goal of surgeryo achieve improvement of vision. Favorable outcomes were achieved with appropriate selection of surgical approach. More studies are necessary to define the prognostic factors for patients in this scenario.

INTRODUÇÃO: Os meningiomas de tubérculo selar certamente representam um desafio para os neurocirurgiões no que se refere ao manejo cirúrgico. Estes tumores representam até 10% de todos os meningiomas intracranianos. A dificuldade em ressecar cirurgicamente estes meningiomas provém da sua relação com os nervos ópticos, com o quiasma óptico e com as artérias carótidas internas, cerebrais anteriores e suas perfurantes. Discutimos as principais abordagens e as complicações com base em nossa série de pacientes e numa revisão da literatura. CASUÍSTICA E MÉTODOS: Relatamos nossa série de casos pessoais de 38 pacientes com meningiomas de tubérculo selar. Trinta e seis pacientes foram submetidos a craniotomia para ressecção tumoral (12 bifrontal, 12 pterional, 6 supraciliar, 4 unilateral frontal e 2 fronto-orbito-zigomático) e 2 receberam abordagem endoscópica endonasal. A escala de Simpson, bem comoaxas de morbidade e mortalidade foram analisadas durante o período pós-operatório, em função das diferentes abordagens. RESULTADOS: Trinta e um pacientes foram submetidos a excisões de grau I e II da escala de Simpson; os demais foram submetidos a excisão de grau IV da mesma escala. A taxa global de morbidade sem acometimento visual foi de 13,15% (5 de 38 pacientes), enquanto a mortalidade evidenciada foi de 5,3% (2 dentre 38 pacientes). CONCLUSÃO: O principal sintoma que leva ao diagnóstico de meningioma de tubérculo selar é o comprometimento visual, de modo que o principal objetivo da cirurgia é alcançar a melhora da visão nestes pacientes. Os resultados alcançados foram favoráveis quando associados com a seleção apropriada da abordagem cirúrgica. Mais estudos são necessários para definir os fatores prognósticos para os pacientes com meningioma de tubérculo selar após intervenção cirúrgica.

A morphological study of the dorsum sellae in human skull / Estudio morfológico del dorsum sellae en el cráneo humano

Anatomical variations in the shape and dimension of the dorsum sellae and posterior clinoid process are common. Most textbooks describe its shape as a median rectangular plate, a square plate, or a transverse ledge on a slope behind the sella turcica (hypophyseal fossa). This work aims to study the dorsum sellae of human skull. One hundred and twenty five dried adult human skulls, irrespective of age, were used for the study. Detailed features of the dorsum sellae were noted and classified into five types: crest like, thin plate, frail quadrilateral plate, heavy square plate, thick elongated plate. Fusion of the posterior and middle clinoid processes in one (unilateral) and all the clinoid processes (anterior, middle, and posterior) in three skulls (unilateral in one, bilateral in two) were also noticed. Findings are discussed in the light of the literature.

Son frecuentes las variaciones anatómicas de la forma y dimensión de dorsum sellae y de los procesos clinoides posteriores. La mayoría de los textos describen su forma como una placa rectangular mediana, una placa cuadrada, o un plano transversal en una pendiente detrás de la sella turcica (fosa hipofisaria). Este trabajo tiene como objetivo estudiar el dorsum sellae en cráneo humano. Para el estudio se utilizaron 125 cráneos humanos adultos secos, de diferentes edades. Se observaron características detalladas de dorsum sellae y se clasificaron en cinco tipos: cresta, al igual que la placa delgada, lámina cuadrilátera, placa cuadrada gruesa, placa alargada gruesa. En tres cráneos se observó fusión de la parte posterior y los procesos clinoides intermedios (unilateral) y los procesos clinoides (anterior, medio y posterior) (unilateral en uno de ellos, bilateral en dos). Los resultados se discuten en consideracion de la literatura.

Pre-operative measurement of the morphometry and angles of the anterior clinoid process (ACP) for aneurysm surgery / Medición preoperatoria de la morfometría y los ángulos del proceso clinoide anterior (PCA) para la cirugía de aneurisma

The anterior clinoid process (ACP) is proximal to vital structures, such as the optic nerve, internal carotid artery and ophthalmic artery; therefore, study of its anatomy is important in guiding and defining surgery. We studied the anatomical structure of the ACP, including the angle formed by the apex of the ACP triangle, and its orientation, to provide information for easier and safer surgery. The measurement was performed on the axial planes of 242 cranial computerized tomography (CT) scans and 27 adult Turkish skulls of both sexes. The length of the ACP, width of the ACP at its base, the angle formed by the apical angle of the ACP triangle and the orientation of the ACP defined according to the sagittal midline were examined. In the Turkish skulls, the length and width of the ACP were similar to previous studies. Our study was the first to measure the angle and orientation of the ACP. The mean angle was 39.67±12.64 (16.6-89.5) and 135 posterior (55 %) and 107 medial (45 %) orientations. Surgical complications can be avoided by pre-operative radiological planning using axial CT scans and by determining whether the morphology is Type 2 (long, narrow, acute-angled), which requires total resection.

El proceso clinoide anterior (PCA) está próximo a estructuras vitales, como el nervio óptico, la arteria carótida interna y la arteria oftálmica, por tanto el estudio de su anatomía es importante en la orientación y la definición de la cirugía de base de cráneo. Se estudió la estructura anatómica de la PCA, incluyendo el ángulo formado por el vértice del triángulo PCA, y su orientación, para proporcionar información para una cirugía más fácil y más segura. La medición se realizó en los planos axiales de 242 exploraciones craneales de tomografía computarizada (TC) y 27 cráneos de individuos adultos turcos de ambos sexos. Se examinó la longitud del PCA, el ancho del PCA en su base, el ángulo formado por el ángulo apical del triángulo PCA y la orientación del PCA definido de acuerdo con la línea mediana sagital. En cráneos turcos, la longitud y el ancho del PCA fueron similares a estudios anteriores. Nuestro estudio fue el primero en medir el ángulo y la orientación del PCA. El ángulo promedio fue de 39,67 ± 12,64 (16,6 a 89,5) y, la orientación fue posterior en 135 cráneos (55 %) y medial en 107 cráneos (45 %). Las complicaciones quirúrgicas pueden evitarse mediante la planificación radiológica preoperatoria através de cortes axiales de tomografía computarizada y determinando si la morfología del PCA es de tipo 2 (larga, estrecha y aguda en ángulo recto), lo que requiere la resección total.

MSCT measurement of anterior clinoid process and clinoid segment of internal carotid artery / 实用放射学杂志

Objective To observe the anatomy status of the anterior clinoid process (ACP)and the anterior clinoid segment of in-ternal carotid artery (ICA)respectively by multisliced computed tomography (MSCT),and to provide useful imaging information for ACP removal surgery.Methods A total of 100 patients (200 sides)had volume rendering reconstruction of skull.Cranium was removed along cranio-orbital bone in simulation.Then the anatomical structures of the ACP and its surrounding were observed in cephalad direction.The total length,medium length,basic width,medium width of the ACP and the sagittal view curve length of anterior clinoid segment of the ICA from both sides were measured.Results Total length of left ACP was (9.82±2.48)mm,basal width was (9.47±1.88)mm,medium length was (5.03±1.55)mm,medium width was (6.1 9 ±1.75)mm;for right side total length was (10.41±2.1 6)mm,basal width was (9.66 ±2.21)mm,medium length was (5.86 ±2.48)mm,medium width was (6.66±1.5 1)mm.Left anterior clinoid segment of ICA curve length was (6.74±2.25)mm;right was (8.54±3.00)mm.Paired sample t test showed no significant difference in total length,basal width and medium width of ACP in both sides (P >0.05);while the difference in medium length and curve length of the anterior clinoid segment of ICA were statistically significant respectively (P <0.05).Conclusion MSCT can clearly display the vivisection and variation status of the ACP and the anterior clinoid segment of the ICA and can provide useful imaging information for removal of ACP in operation.

Application effect analysis of anterior clinoid process drilled off via epidural approach in posterior communicating artery aneurysm clipping / 中国脑血管病杂志

Objective To investigate the application effect of anterior clinoid process drilled off via epidural approach in posterior communicating artery aneurysm ( PCoAA) clipping. Methods The clinical data of 42 patients with PCoAA who underwent craniotomy from January 2012 to January 2014 were analyzed retrospectively,including 22 patients performed anterior clinoid process drilled off and 20 did not. The difficult or easy degree of intraoperative aneurysm clipping and postoperative efficacy were analyzed. Results The aneurysms in 22 patients underwent anterior clinoid process were clipped satisfactorily. The brain retractor was not used during the procedure. Only one patient had cerebral infarction after procedure. No patients had oculomotor nerve paralysis and incomplete clipping of aneurysms. Of the 20 patients without the anterior clinoid process drilled off,3 aneurysms were clipped incompletely because it was difficult to implant aneurysm clips, 2 had cerebral infarction, and 1 had oculomotor nerve paralysis. Conclusion Removing the anterior clinoid process drilled off via extradural approach may bring convenience for PCoAA clipping. It can effectively avoid the difficulty of implanting aneurysm clips during the procedure. Its application is safe and can reduce postoperative complications.

A Case of Recurred Visual Loss Caused by Anterior Clinoid Process Mucocele / 대한이비인후과학회지

The anterior clinoid process may be pneumatized by an extension of the sphenoid sinus air space. An anterior clinoid mucocele is a particularly rare entity, which can lead to optic complication due to its proximity to the optic nerve. Optic neuropathy is seldom recoverd if there is a delay in treatment for more than 10 days. The primary treatment for mucocele is surgical excision. We report a patient with mucocele of the anterior clinoid process that resulted in recurrent monocular visual loss. The patient underwent endoscopy-assisted transnasal marsupialization of mucocele with full recovery of visual function.

Multislice Spiral CT-based Simulation in Enlarging Exposure Extent of Internal Carotid Artery Siphon Before and After Removing Anterior Clinoid / 中国医学影像学杂志

Purpose To study the exposure extent of internal carotid artery siphon (ICAS) before and after removing anterior clinoid process (ACP) using multislice spiral CT (MSCT) simulation, and to improve the tumor resection rate and ensure the operation effect. Materials and Methods MSCT three-dimensional images reconstruction simulating supraorbital keyhole approach of 100 patients (200 sides) were observed, the distance between the crotch of anterior cerebral artery and middle cerebral artery and ICAS before and after removing ACP (exposure extent) was measured. Results In 100 patients (200 sides ACP), the exposure extent before and after removing ACP were (14.3±3.9) mm and (30.5±4.2) mm, respectively on the left side with statistical difference (t=45.278, P0.05). Conclusion MSCT simulating supraorbital keyhole approach in removing ACP can effectively increase the exposure length of ICA, and enlarge the exposure extent of sella region, thus provide reliable imaging information for removing tumor and selecting surgical project in this region.

Measurement of Critical Structures around Paraclinoidal Area : A Cadaveric Morphometric Study

OBJECTIVE: Although removal of the anterior clinoid process (ACP) is essential surgical technique, studies about quantitative measurements of the space broadening by the anterior clinoidectomy are rare. The purposes of this study are to investigate the dimension of the ACP, to quantify the improved exposure of the parasellar space after extradural anterior clinoidectomy and to measure the correlation of each structure around the paraclinoidal area. METHODS: Eleven formalin-fixed Korean adult cadaveric heads were used and frontotemporal craniotomies were done bilaterally. The length of C6 segment of the internal carotid artery on its lateral and medial side and optic nerve length were checked before and after anterior clinoidectomy. The basal width and height of the ACP were measured. The relationships among the paraclinoidal structures were assessed. The origin and projection of the ophthalmic artery (OA) were investigated. RESULTS: The mean values of intradural basal width and height of the ACP were 10.82 mm and 7.61 mm respectively. The mean length of the C6 lateral and medial side increased 49%. The mean length of optic nerve increased 97%. At the parasellar area, the lengths from the optic strut to the falciform liament, distal dural ring, origin of OA were 6.69 mm, 9.36 mm and 5.99 mm, respectively. The distance between CN III and IV was 11.06 mm. CONCLUSION: With the removal of ACP, exposure of the C6 segments and optic nerve can expand 49% and 97%, respectively. This technique should be among a surgeon's essential skills for treating lesions around the parasellar area.

Bony Protuberances on the Anterior and Posterior Clinoid Processes Lead to Traumatic Internal Carotid Artery Aneurysm Following Craniofacial Injury

Traumatic intracranial aneurysms are rare, comprising 1% or less of all cerebral aneurysms. The majority of these aneurysms arise at the skull base or in the distal anterior and middle cerebral arteries or their branches following direct mural injury or acceleration-induced shearing force. We present a 50-year-old patient in whom subarachnoid hemorrhage (SAH) was developed as a result of traumatic aneurysm rupture after a closed craniofacial injury. Through careful evaluation of the three-dimensional computed tomography and conventional angiographies, the possible mechanism of the traumatic internal carotid artery trunk aneurysm is correlated with a hit injury by the bony protuberances on the anterior and posterior clinoid processes. This traumatic aneurysm was successfully obliterated with clipping and wrapping technique. The possibility of a traumatic intracranial aneurysm should be considered when patient with SAH demonstrates bony protuberances on the clinoid process as a traumatic aneurysm may result from mechanical injury by the sharp bony edges.

Analysis of Angiographic Findings and Clinical Impact of Anterior Clinoidectomy in Internal Carotid-Posterior Communicating Artery Aneurysm Surgery - Clinical Research - / 대한뇌혈관외과학회지

OBJECTIVE: In the case of internal carotid-posterior communicating (ICPCom) artery aneurysm it is possible to successfully clip the aneurysmal neck without any difficulty. However, if the aneurysmal neck is wide, the aneurysmal sac is giant, the aneurysmal sac is hidden by the anterior clinoid process (ACP), or its dome is located in ventral portion or low-lying ICPCom aneurysm, it is difficult to open the proximal aneurysmal neck and we encounter a barrier in controlling bleeding in case of premature rupture of the aneurysm. They need to be resected the ACP for successful aneurysmal clipping. We propose angiographic criteria for predicting necessity of resection of the ACP before clipping of the ICPCom artery aneurysm. METHODS: Between 1999 and 2003, 16 patients with ICPCom artery aneurysm were treated with the resection of the ACP prior to applying the clip on the neck of the aneurysm. We retrospectively analyzed the preoperative cerebral angiographies, and the clinical and operative findings. We measured various radiometric parameters to reveal the angiographic characteristics. RESULTS: The mean value of the radiographic measurement in case of the cerebral angiography in 16 patients is as follows: angle A (the angle between the midline of the skull and the axis of the C1 segment on A-P view) ranged from 15 to 80 degrees (mean+/-SD, 42+/-5 degrees), angle B (the angle between the axes of the C1 and C2 segments on A-P view) ranged from 70 to 150 degrees (mean+/-SD, 110+/-15 degrees), and distance C (the distance between the tip of the ACP and the most proximal portion of the aneurysmal neck on the lateral view) ranged from 2 to 9 mm (mean+/-SD, 4.5+/-1 mm). CONCLUSION: We have resected the ACP in 16 of the 40 ICPCom aneurysms. The mean values of angle A, angle B, and distance C is 42+/-5 degrees, 110+/-15 degrees, and 4.5+/-1 mm, respectively. We did not encounter any difficulty in clipping in all the cases in which there was no premature rupture of the aneurysm. Most of cases had a good outcome.

Endoscopic Treatment of Anterior Clinoid Process Mucocele: 3 Cases / 대한이비인후과학회지

The anterior clinoid process, the medial end of the lesser wing of the sphenoid bone, may be pneumatized by sphenoid sinus as part of normal development. The cases of sphenoid mucocele described in literature are sparse, especially located in anterior clinoid that is a bone structure seldom presenting pneumatization. Therefore generally showing no anatomic substrate justifying the development and the growth of a mucocele, have to be considered really exceptional. We present three cases of anterior clinoid process mucocele which were managed by a endoscopic transnasal transsphenoidal approach.

Morphometric Aspect of Juxta-Clinoidal Cranial Nerves / 대한뇌혈관학회지

OBJECTIVE: During anterior clinoidectomy for aneurysms of ophthalmic artery or paraclinoidal lesions, not only optic nerve but also cranial nerves passing through the superior orbital fissure (SOF) can be damaged by mechanical or thermal injury. Particularly, revision for paraclinoidal lesions can give further damage to the cranial nerves because of the obscure anatomical structure resulting from the tight fibrous adhesion. Thus, to reduce the damage of the cranial nerves passing through the SOF during the anterior clinoidectomy or optic canal decompression via the extradural or intradural route, morphometric relationship of juxta-clinoidal cranial nerves were studied. MATERIALS AND METHODS: Using 15 adult formalin fixed cadavers, the anatomical landmarks for measurements were chosen as follows: lateral entry point of optic nerve into the optic canal (LON), tip of anterior clinoid process (ACP), tip of posterior clinoid process (PCP), upper border of lesser wing of sphenoid bone, and lateral end of SOF. The measurements were carried out as follows: 1) distance from the LON to the dural entry point (DEP) of the third (III), fourth (IV), and ophthalmic branch of the fifth (V1) nerves into the tentorium, 2) distance from the tip of PCP to the DEP of III and VI cranial nerves, 3) distance from the LON to the cranial nerves within intradural space before passing through SOF, 4) The shortest depth from the tip of ACP and the edge of lesser wing to the cranial nerves passing through the cavernous sinus, 5) distance from the lateral end of SOF to the cranial nerves just before passing through the annular tendon. RESULTS: The mean distance from the LON to the DEP of the III, IV, and V1 cranial nerves were 10.4 mm, 18.8 mm, and 23.4 mm, respectively. The mean distance from the tip of PCP to the DEP of the III and VI cranial nerves were 5.4 mm and 18.6 mm, respectively. DEP of the III cranial nerve was corresponded with the just anterior coronal plane of PCP. The mean distance from the LON to the III, IV, and V1 cranial nerves passing through the SOF were 7.2 mm, 10.0 mm, 10.5 mm and 10.6 mm, respectively. The III cranial nerve located at a mean depth of 3.4 mm from the tip of ACP. The IV, V1 , and VI cranial nerves located at a mean depth of 2.1 mm, 2.4 mm and 7.4 mm from the upper border of lesser wing of sphenoid bone, respectively. The III cranial nerve splitted into superior and inferior divisions at a mean distance of 1.51 mm from the lateral end of SOF, just before where it passes through the SOF. The mean distance from the lateral end of SOF to the lateral margins of the III, IV and frontal nerves of V1 were 12.5 mm, 11.0 mm and 10.2 mm, respectively. CONCLUSION: DEP of the III cranial nerve was corresponded with the just anterior coronal plane of PCP and was about a half distance from PCP than from LOP. DEP of the IV cranial nerve looks like same site as that of V1 cranial nerve, but IV cranial nerve located at just superior to V1. From the LON, III, IV, V1 , and VI CNs latero-inferiorly passed through the SOF. The III cranial nerve located at the most medial portion of SOF with a mean distance of 7 mm, and the IV, V1 and VI cranial nerves were arranged in the same order as vertical arrangement with a mean distance of 10 mm. The cranial nerves just before passing through SOF were located at a range of 7.8 to 20 mm from the lateral end of SOF. This study facilitates an understanding of the anatomy of juxta-sellar region and may help to reduce the cranial nerve injury at the surgery around juxta-clinoidal CNs.

A Case of Mucocele in Optic Canal

Intraorbital or intracranial mucoceles usually arise from paranasal sinus and enlaarge sufficiently to compress orbital or intracranial structures: primary intraorbitocranial mucocele developing from optic canal or anterior clinoid process is extrmely rare. We experienced a case of 48-year-old female patient presenting headache and diplopia with 5 days` duration, whose primary mucocele had arisen from anterior clinoid process near the optic canal unassociated with paranasal sinus. We report the case herein with a review of the literature.

Anterior clinoid process and optic strut in Koreans

The anterior clinoid process and the optic strut are often removed during operation on the anterior part of the cavernous sinus. Therefore it is important for neurosurgeons to verify their dimensions and variations. The purpose of this study was to investigate the dimension and the variation of the anterior clinoid process and to describe the locational variation of the optic strut. Seventy-three skulls of Korean adults were used. The average length, basal width and thickness of the anterior clinoid process were 9.18 +/- 1.55, 9.63 +/- 1.49 and 5.32 +/- 1.07 mm, respectively. The average thickness of the optic strut was 2.9 +/- 1.15 mm and it was commonly attached to anterior two-fifths of the anterior clinoid process. The complete caroticoclinoid canal was observed in 4.1%, however it was incomplete in 11.6%. The incidence of a caroticoclinoid canal in Koreans was relatively low compared with other races.

Classification and Surgical Treatment of Paraclinoid Aneurysms

Paraclinoid aneurysms arose from the proximal internal carotid artery between the site of emergence of carotid artery from the roof of the cavernous sinus and posterior communicating artery. Surgery of these aneurysms presents special difficulties because of its complicated osseous, dura, and neurovascular structures;sella turcica, cavernous sinus, optic nerve. The clinical and radiological characteristics in twenty-seven patients with the paraclinoid aneurysms were reviewed and classified into four subgroups according to their branch of origin in this segment;1) carotid cave aneurysm(2 cases), 2) ophthalmic artery aneurysm(11 cases), 3) superior hypophyseal artery aneurysm(11 cases), 4) proximal posterior carotid artery wall aneurysm or global type aneurysm(3 cases). Surgery required orbital unroofing and removal of anterior clinid process with release of dural ring. To provide easy proximal control, exposure of cervical carotid artery was helpful in some cases. Preoperative balloon occlusion testing was man datory. Outcomes were considered as good to fair in 19 patients, poor in five, and three patients died. The patients who had poor results were poor preoperative status-four were grade IV, one was grade II(Hunt-Hess grade). The causes of death were premature rupture(2 cases) and extensive vasospasm(1 case). Preoperative classification of these lesions provides excellent correlation of operative findings and surgical preparation to expose the proximal part of internal carotid artery.

Surgical Treatment of Posterior Circulation Aneurysms

Aneurysms arising from the posterior circulation are 5-19% of total intracranial aneurysms. Althought many neurosurgeons have challended with various innovations but the confinned surgical space, complicated anatomical structure and many small perforators to vital organ of brain were remained the barrier that we we have to overcome. From July 1987 to December 1994, we have been operated on 23 cases of posterior circuation aneurysms among 409 cases of surgically treated all intracranial aneurysms. The present 5.6% of all intracranial aneurysms, the average age of these patients was 49 years old. The ratio of male to female was 1 : 1.8. The number of basilar bifurcation artery aneurysms(BBAA) were 14(61%), the posterior cerebral artery(PCA) aneurysms 3(13%), the upper basilar trunk aneurysm 1, posterior inferior cerebellar artery(PICA) aneurysm 3(13%), anterior inferior cerebellar artery(AICA) aneurysm 1 and vertebral artery aneurysm 1. Five patients had accompanined with anterior circulation aneurysm and one patient had concomitant arteriovenous malformation. We have successfully clipped 12 cases and wrapped 2 cases of BBAA aneurysms through modified pterional approach and subtemporal approach according to the hight of basilar bifurcation and the other posterior circulation aneurysms are all clipped through most available approaches including lateral, far-lateral suboccipital and interhemispheric approach. Surgical outcome was good in 15 cases, fair in 4 cases, poor in 3 cases and one patient expired.

Large and Giant Paraclinoid Aneurysms Treated by Combined Extradural and Intradural Approach

Between May, 1992 and April, 1993, four patients with paraclinoid aneurysms were treated by a direct operative approach. Two patients had large aneurysms, all of which had ruptured, presented with subarachnoid hemorrhage(SAH). The other two patients had giant aneurysms, causing visual symptoms by optic nerve compression. All patients were treated by a combined extradural and intradural approach. All the aneurysms were successfully clipped and collapsed or resected, eliminating the risk of rebleeding and decompressing the visual system immediately and effectively, while preserving the blood flow of the carotid artery and its branches. Removal of the individual bony structure including anterior clinoid process(ACP) and orbital roof at the skull base extradurally provides a better and safer exposure of the aneurysm, and of the ophthalmic segment of the carotid artery than does excessive retraction of the brain. This technique also affords exposure of the internal carotid artery proximal to the lesion and ophthalmic artery, which is important in securing safe and complete occlusion of the aneurysm. Authors present operative technique, summary of cases, and literature review.

Extradural-Intradural Approach to Carotid-Ophthalmic Artery Aneurysm

The authors report seven cases of carotid-ophthalmic artery aneurysms who were surgically treated using the combined extradural-intradural or intradural approach from March, 1991, to December, 1993. Carotid-ophthalmic artery aneurysms are of considerably surgical interest because some of these were considered to have technical difficulties of clipping and disastrous surgical results. Removal of the anterior clinoid process and unroofing of the optic canal are the key points to exposure the operative field adequately. On the basis of these experiences, authors concluded that this approach is very useful, because of adequate surgical field and better mobilization of the internal carotid artery and optic nerve for direct clipping of carotid-ophthalmic artery aneurysm and basilar tip aneurysm.