Anatomic and Surgical Basis of the Sphenoid Ridge Keyhole Approach for Cerebral Aneurysms

2005 ◽  
Vol 56 (suppl_1) ◽  
pp. ONS-178-ONS-185 ◽  
Author(s):  
Edgar Nathal ◽  
Juan Luis Gomez-Amador
Keyword(s):  
Anterior Part ◽  
Cerebral Aneurysms ◽  
Circle Of Willis ◽  
Sylvian Fissure ◽  
Clear Understanding ◽  
Pterional Approach ◽  
Anterior Clinoid Process ◽  
Keyhole Approach ◽  
Sphenoid Ridge ◽  
Basal Cisterns

Abstract IN VASCULAR NEUROSURGERY, the pterional approach has been used primarily for the treatment of a wide variety of diseases (cavernous angiomas, arteriovenous malformations, etc.), and it is used to take advantage of naturally occurring planes and spaces to expose the major structures of the circle of Willis. It provides access to the major part of the anterior circulation aneurysms and those occurring in the upper and most proximal part of the posterior circulation. Conversely, there has been an increasing interest in the so-called minimally invasive procedures or keyhole approaches to treating cerebral aneurysms in specific locations. In this work, we describe a novel keyhole approach that was conceived to achieve the angle of vision and advantages of the classic pterional approach. This surgical approach is based on the anatomic location of the sphenoid ridge and its relationship with the sylvian fissure and basal cisterns. The initial incision is made over the hairline behind the external border of the eye on the side selected. A skin and muscular flap is reflected anteriorly, and a small 3 × 3-cm craniotomy is completed around the external landmarks of the sphenoid ridge. Further extradural drilling is completed down to the anterior clinoid process. The dura is opened in a semilunar manner, and the sylvian fissure is opened completely to reach the sylvian and basal cisterns. Thereafter, the aneurysm is dissected and clipped according to the standard microtechnique of the neurosurgeon. A step-by-step description of the approach is offered in this work to facilitate a clear understanding of it. We recommend this approach for treatment of aneurysms arising at the anterior part of the circle of Willis. It has the advantages of less operative time, fewer days of hospitalization, and similar morbidity and mortality compared with the standard pterional craniotomy (5.7% on our service for nongiant ruptured aneurysms).

scholarly journals Extended Lateral Orbital Craniotomy: Anatomic Study and Initial Clinical Series of a Novel Minimally Invasive Pterional Approach

2019 ◽  
Vol 81 (01) ◽  
pp. 088-096
Author(s):  
Mithun G. Sattur ◽  
Karl R. Abi-Aad ◽  
Matthew E. Welz ◽  
Rami James Aoun ◽  
Chandan Krishna ◽  
...  
Keyword(s):  
Minimally Invasive ◽  
Minimum Distance ◽  
Sylvian Fissure ◽  
Fat Pad ◽  
Anatomic Study ◽  
Clinical Series ◽  
The Mean ◽  
Keyhole Approach ◽  
Bone Exposure ◽  
Sphenoid Ridge

Background Of the minimally invasive “keyhole” alternatives to the pterional region, the supraorbital eyebrow approach is the most widely adopted. Yet it can prove disadvantageous when a more direct lateral microsurgical trajectory of attack to the Sylvian fissure and anterior middle fossa are needed. Objective The extended lateral orbital (XLO) approach was designed to be direct and minimally invasive, with the sphenoid ridge at the center of exposure. Methods Five injected cadaver heads were used for anatomic study of the XLO approach. The anatomic course of the frontalis branch of facial nerve was studied in relation to the XLO incision. Following XLO incision, the bone exposure was measured. The intracranial microsurgical exposure was assessed subjectively. Application of the technique in representative clinical operative cases is provided. Results The frontalis nerve was protected in the subgaleal fat pad, with an average minimum distance of 2.3 cm from the XLO incision. The mean calvarial area exposure was 4.95 cm2 and consistently centered on the sphenoid ridge. Excellent access to ipsilateral Sylvian's fissure, perisylvian regions, and supra-/parasellar structures was possible. The main limitations related to exposure of the posterior Sylvian fissure and the expected limitations of microsurgical instrument manipulation from a smaller craniotomy. Conclusions The XLO approach is a minimally invasive keyhole approach to the pterional region that affords a unique lateral trajectory via a craniotomy centered on the sphenoid ridge. Excellent exposure to properly selected lesions is possible. The incision is at a safe distance from the frontalis branch and shows excellent cosmetic healing.

Exposure of the anterior part of the circle of Willis in the dog

1974 ◽  
Vol 41 (1) ◽  
pp. 107-112
Author(s):  
Shigeaki Hori ◽  
Williamina A. Himwich
Keyword(s):  
Anterior Part ◽  
Cerebral Arteries ◽  
Circle Of Willis ◽  
Content Type ◽  
Anatomical Characteristics ◽  
Fine Print

✓ A technique for exposing the vessels in the anterior part of the circle of Willis in the dog is described. Some of the physiological and anatomical characteristics of the anterior communicating and the anterior cerebral arteries are discussed.

Surgery for angiographically occult cerebral aneurysms

1993 ◽  
Vol 79 (5) ◽  
pp. 674-679 ◽  
Author(s):  
Jafar J. Jafar ◽  
Howard L. Weiner
Keyword(s):  
Cerebral Aneurysms ◽  
Artery Aneurysm ◽  
Sylvian Fissure ◽  
Ct Scans ◽  
Anterior Communicating Artery ◽  
Content Type ◽  
Excellent Outcome ◽  
Interpeduncular Cistern ◽  
Spontaneous Subarachnoid Hemorrhage ◽  
Exploratory Surgery

✓ In 15% of patients with spontaneous subarachnoid hemorrhage (SAH), the source of bleeding cannot be determined despite repeated cerebral angiography. However, some patients diagnosed as having “SAH of unknown cause” actually harbor undetected aneurysms. The authors report six patients with SAH who, despite multiple negative cerebral angiograms, underwent exploratory surgery due to a high clinical and radiographic suspicion for the presence of an aneurysm. Brain computerized tomography (CT) scans revealed blood located mainly in the basal frontal interhemispheric fissure in four patients, in the sylvian fissure in one patient, and in the interpeduncular cistern in one patient. The patients were evaluated as Hunt and Hess Grades I to III, and had undergone at least two high-quality cerebral angiograms that did not reveal an aneurysm. Vasospasm was visualized in two patients. Three patients rebled while in the hospital. Exploratory surgery was performed at an average of 12 days post-SAH. Five aneurysms were discovered at surgery and were successfully clipped. All four patients with interhemispheric blood were found to have an anterior communicating artery (ACoA) aneurysm. The patient with blood in the sylvian fissure was found to have a middle cerebral artery aneurysm. These aneurysms were partially thrombosed. No aneurysm was detected in the patient with interpeduncular SAH, despite extensive basilar artery exploration. Five patients had an excellent outcome and one patient developed diabetes insipidus. These results show that exploratory aneurysm surgery is warranted, despite repeated negative cerebral angiograms, if the patient manifests the classical signs of SAH with CT scans localizing blood to a specific cerebral blood vessel (particularly the ACoA) and if a second SAH is documented at the same site.

OLFACTORY DYSFUNCTION AFTER IPSILATERAL AND CONTRALATERAL PTERIONAL APPROACHES FOR CEREBRAL ANEURYSMS

Neurosurgery ◽  
2009 ◽  
Vol 65 (4) ◽  
pp. 727-732 ◽  
Author(s):  
Jaechan Park ◽  
Sun-Ho Lee ◽  
Dong-Hun Kang ◽  
Jung-Soo Kim
Keyword(s):  
Aneurysmal Subarachnoid Hemorrhage ◽  
Cerebral Aneurysms ◽  
Olfactory Dysfunction ◽  
Anterior Communicating Artery ◽  
Pterional Approach ◽  
Anterior Circulation ◽  
Related Risk ◽  
Lateral Distance ◽  
Contralateral Pterional Approach ◽  
Anterior Circulation Aneurysms

Abstract OBJECTIVE This study investigated olfactory dysfunction after using a contralateral or ipsilateral pterional approach for anterior circulation aneurysms and related risk factors. METHODS This study included 189 patients who experienced an aneurysmal subarachnoid hemorrhage and in whom a pterional approach was used, including a contralateral pterional approach (12 patients), a pterional approach for an anterior communicating artery (AComA) aneurysm (70 patients), and an ipsilateral pterional approach for aneurysms of the anterior circulation, excluding the AComA (107 patients). In addition to questionnaires on olfactory function, Sniffin' Sticks tests were performed 12 to 38 months after the operation. RESULTS The incidence of olfactory dysfunction was high: 58% (7 of 12) with a contralateral pterional approach, 14% (10 of 70) with a pterional approach for an AComA aneurysm, and 4% (4 of 107) with an ipsilateral pterional approach for aneurysms of the anterior circulation, except for the AComA. In addition, patients 55 years and older had a higher incidence of olfactory dysfunction. Among the 12 patients in whom the contralateral pterional approach was used, 5 (42%) were anosmic and 2 (17%) were hyposmic. The incidence of olfactory dysfunction was also significantly higher at ages 55 years and older. The size and location of the contralateral aneurysm, if small (<1 cm) and located within a 3-cm lateral distance from the midline, were not found to influence the incidence. CONCLUSION A higher incidence of olfactory dysfunction was found in those patients in whom a contralateral pterional approach and a pterional approach for an AComA aneurysm were used. Another major risk factor was an age of 55 years and older.

scholarly journals Association between Circle of Willis Configuration and Rupture of Cerebral Aneurysms

Medicina ◽  
2019 ◽  
Vol 55 (7) ◽  
pp. 338
Author(s):  
Stojanović ◽  
Kostić ◽  
Mitić ◽  
Berilažić ◽  
Radisavljević
Keyword(s):  
Cerebral Aneurysm ◽  
Intracranial Hemorrhage ◽  
Lower Incidence ◽  
Cerebral Aneurysms ◽  
Aneurysm Rupture ◽  
Circle Of Willis ◽  
Type B ◽  
Brain Aneurysms

Background and Objectives: Intracranial hemorrhage caused by the rupture of brain aneurysms occurs in almost 10 per 100,000 people whereas the incidence of such aneurysms is significantly higher, accounting for 4–9%.Linking certain factors to cerebral aneurysm rupture could help in explaining the significantly lower incidence of their rupture compared to their presence. The aim of this study is to determine the association between the corresponding circle of Willis configurations and rupture of cerebral aneurysms. Materials and Methods: A group of 114 patients treated operatively for aruptured cerebral aneurysm and a group of 56 autopsied subjects were involved in the study. Four basic types of the circle of Willis configurations were formed—two symmetric types A and C, and two asymmetric types B and D. Results: A statistically significantly higher presence of asymmetry of the circle of Willis was determined in the group of surgically-treated subjects (p = 0.001),witha significant presence of asymmetric Type B in this group (p < 0.001). The changeson the A1 segment in the group of surgically-treated subjects showed a statistically significant presence compared to the group of autopsied subjects (p = 0.001). Analyzing the presence of symmetry of the circle of Willis between the two groups, that is, the total presence of symmetric types A and C, indicated their statistically significant presence in the group of autopsied patients (p < 0.001). Conclusions: Changes such as hypoplasia or aplasia of A1 and the resulting asymmetry of the circle of Willis directly affect the possibility of the rupture of cerebral aneurysms. Detection of the corresponding types of the circle of Willis after diagnostic examination can be the basis for the development of a protocol for monitoring such patients.

scholarly journals Average dimensions of the vessels at the base of the brain and the embryological basis of its variations

2013 ◽  
Vol 02 (04) ◽  
pp. 180-189
Author(s):  
Iqbal S.
Keyword(s):  
Anterior Part ◽  
Cerebral Arteries ◽  
Cerebral Dominance ◽  
Circle Of Willis ◽  
Detailed Knowledge ◽  
Differential Growth ◽  
Ischemic Attack ◽  
The Individual ◽  
The Right ◽  
The Brain

Abstract Background and aims: The cerebral circulation is constantly maintained by the anastomotic circle of Willis which is often anomalous in more than 50% of the normal adult brains. These anomalies increase the risk of the stroke and transient ischemic attack in older patients. Adequate blood flow through the circle of Willis is often necessary to prevent these ischemic infarctions. The anomalies of cerebral vessels are directly related to the differential growth of various parts of the brain. A detailed knowledge of the individual measurements of the cerebral arteries is useful to neurosurgeon in planning the shunt operations and in the choice of their patients. The present study is aimed to analyze the average dimensions of the vessels at the base of brain and an attempt to explain the common form of variations in terms of embryological development. Materials and methods: Fifty adult cadaveric brains were obtained from routine cadaveric dissections. The base of the brain with the circle of Willis was fixed in 10% formalin and preserved. The circle was analyzed for variations in the size, length and number of the component vessels and any asymmetry in the configuration. The dimensions of the vessels forming the circle were measured using graduated calipers. The observations were recorded and tabulated. Results: Asymmetry was observed in 10% to 36% of the circles in this study. Anomalies were more common in the posterior than in the anterior part of the circle. The posterior anomalies included hypoplastic vessels, absent vessels and embryonic derivation while anterior anomalies were predominantly of accessory vessels. Middle cerebral artery exhibited the least variations. In majority of the circles, left sided vessels were larger in diameter than the right. Conclusions: Variations are more common in the posterior than in the anterior part of the circle and on the right than on the left side of the brain. There was no correlation between the variations of circle of Willis of the right side and the left cerebral dominance. There seems to be no difference between races, concerning the anatomic variations of the brain circulation.

scholarly journals Keyhole Approach and Neuroendoscopy for Cerebral Aneurysms

2017 ◽  
Vol 60 (3) ◽  
pp. 275-281 ◽  
Author(s):  
Won-Sang Cho ◽  
Jeong Eun Kim ◽  
Hyun-Seung Kang ◽  
Young-Je Son ◽  
Jae Seung Bang ◽  
...  
Keyword(s):  
Cerebral Aneurysms ◽  
Keyhole Approach

Computational Fluid Dynamics Simulation of the Blood Flow in the Circle of Willis

2002 ◽  
Author(s):  
M. Harazawa ◽  
T. Yamaguchi
Keyword(s):  
Blood Flow ◽  
Blood Supply ◽  
Internal Carotid ◽  
Complex Geometry ◽  
Cerebral Aneurysms ◽  
Cerebrovascular Diseases ◽  
Circle Of Willis ◽  
Dynamics Simulation ◽  
The Brain ◽  
Internal Carotid Arteries

The blood supply for the brain is born by four arteries, that is, two internal carotid arteries and two vertebral arteries. They are mutually connected at the cerebral base, and form a closed arterial circle, called the circle of Willis, so that the safety of the brain blood supply is increased. However their anastomoses show a very wide variety of atypism. If some of anastomses are very thin, or even do not exist, the safety of the blood supply is not secured. This is particularly important when some diseases such as cerebral thrombosis occurs and the blood flow supply stops unilaterally. Redistribution of the blood supply in such cases is thought to be strongly affected by geometrical configuration of the anastomoses. It is also known that cerebral aneurysms, which may induce serious cerebrovascular diseases, preferentially occur at the circle of Willis. Complex blood flow pattern has been suspected of having an influence on this preference. This is again dependent on complex geometry of the circle.

The Transpalpebral Versus the Transciliary Variant of the Supraorbital Keyhole Approach: Anatomic Concepts for Aneurysm Surgery

2019 ◽  
Vol 19 (1) ◽  
pp. E24-E31
Author(s):  
Jonathan Rychen ◽  
Daniel W Zumofen ◽  
Howard A Riina ◽  
Luigi Mariani ◽  
Raphael Guzman
Keyword(s):  
Potential Role ◽  
Skin Incision ◽  
Aneurysm Surgery ◽  
Orbital Roof ◽  
Anterior Aspect ◽  
Keyhole Approach ◽  
Orbital Rim ◽  
Neurovascular Structures ◽  
Sphenoid Ridge ◽  
Supraorbital Craniotomy

Abstract BACKGROUND The supraorbital craniotomy (SOC) is classically performed through a skin incision in the patient's eyebrow. A variant with a skin incision in the patient's eyelid has become increasingly popular in recent years. OBJECTIVE To compare the transpalpebral and the transciliary variants of the SOC with regard to their potential role in aneurysm surgery. METHODS We carried out cadaveric dissections and virtual craniotomies on computerized tomography datasets. The skin incision, the craniotomy location and size, the working angles, and the achievable exposure of neurovascular structures were assessed and compared for both variants of the SOC. RESULTS The skin incision measured 4 cm for the transpalpebral and 3 cm for the transciliary variant. The skin could be retracted 1.5 cm upward from the lower edge of the orbital rim with the transpalpebral and 2.5 cm upward with the transciliary variant. The craniotomy size was 2.5 × 1.5 cm for both variants, given that the transpalpebral variant included an orbital osteotomy. The bony opening in the transpalpebral variant was 1 cm more caudal; this restricted the craniocaudal working angles and, thereby, limited the achievable exposure of neurovascular structures in the paraclinoid area and along the sphenoid ridge. CONCLUSION If the orbital rim and the anterior aspect of the orbital roof are removed, then the transpalpebral variant of the SOC enables a bony opening that is just as large as that of the transciliary variant. Nonetheless, the more caudal location of the bony opening alters the available working angles and may impede exposure of key structures during aneurysm surgery.

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