Petroclival meningiomas: update of current treatment and consensus by the EANS skull base section.

BACKGROUND: The optimal management of petroclival meningiomas (PCMs) continues to be debated along with several controversies that persist. METHODS: A task force was created by the EANS skull base section along with its members and other renowned experts in the field to generate recommendations for the management of these tumors. To achieve this, the task force reviewed in detail the literature in this field and had formal discussions within the group. RESULTS: The constituted task force dealt with the existing definitions and classifications, pre-operative radiological investigations, management of small and asymptomatic PCMs, radiosurgery, optimal surgical strategies, multimodal treatment, decision-making, and patient's counselling. CONCLUSION: This article represents the consensually derived opinion of the task force with respect to the management of PCMs.

Tailoring the cranio-orbital approach.

The various modifications and variations of the cranio-orbital approach have been recently described; the author uses different modifications according to the location, size and extent of the lesion. Some of the prime indications for these modifications are presented herein.

Neurosurgical training in the countries of the Middle East: a summary round table discussion held at the annual meeting of the Middle East Neurosurgical Society, April 1983, Athens, Greece.

At the combined Annual Meeting of the Hellenic Neurosurgical Society and the Middle East Neurosurgical Society in Athens on April 10-13, 1983, a round table discussion of neurosurgical training in the Middle East took place. The types of training programs available in the panel members' respective countries were discussed, and the quality, requirements, and standards of training were delineated. Neurosurgical manpower in the Middle East was reviewed. The panelists explored the need for unification of programs and standardization and review of training and called for a well-recognized certification in neurosurgery among the countries of the Middle East.

Supraorbital-pterional approach to skull base lesions.

A surgical approach to the skull base is described. It allows excellent exposure of the cranial base with minimal brain retraction. Deep lesions can be handled via subfrontal, transsylvian, or subtemporal routes during the same operation. This approach is most suitable for large lesions in the suprasellar, parasellar, and retrosellar areas and for those that extend into the cavernous sinus, along the tentorial notch, or into the orbit. After the single bone flap is replaced, there is little or no functional, anatomical, or cosmetic deficit. Our experience in 16 cases and suggestion for the use of this approach are presented.

M. Gazi Yasargil: the time in Little Rock.

Microneurosurgery is Professor Yasargil's legacy. Its impact on patient outcomes, surgeons' abilities, the field of neurosurgery in particular, and the art of surgery in general is great, profound, and everlasting. Professor Yasargil led a revolution that has transformed neurosurgery into the fine art we practice today. His ingenuity, devotion, energy, and masterful technique have made his contributions so salient that they have earned him recognition as Neurosurgery's Man of the Century. It has been an honor, a great opportunity, and a phenomenal experience to spend the last 5 years with him at the University of Arkansas for Medical Sciences in Little Rock. There, he represents the very best in knowledge, expertise, dexterity, and, above all, devotion to advancing the field of neurosurgery. Most enjoyable have been his stimulating intellect and inspiring vision.

Suprasellar arachnoid cysts: an extension of the membrane of Liliequist.

A case of suprasellar arachnoid cyst and hydrocephalus diagnosed by computed tomography (CT) and positive-contrast ventriculography is presented. Transfrontal exploration of the 3rd ventricle revealed findings consistent with the cyst being, in fact, a large forward and upward diverticulum of the arachnoidal membrane of Liliequist. The authors suggest that some of the other similarly located arachnoid cysts are extensions of this membrane imperforate by previous infection, hemorrhage, or maldevelopment.

Intravagal paragangliomas: report of four cases.

The intravagal paraganglioma is a very rare tumor of the head and neck that accounts for only 5% of the paragangliomas in that area. A painless mass in the high neck with extension into the peripharyngeal space is the most common characteristic of this tumor. Malignant paragangliomas with invasion of the cervical lymph nodes and carotid artery have been reported, but the presence of metastasis, rather than the histological findings, is the only parameter for classifying them as malignant tumors. Despite the numerous descriptions of the efficacy of radiation therapy, the histological findings of irradiated specimens have shown little effect of radiation therapy on the chief cells. The only curative therapy for intravagal paragangliomas is the total resection of the tumor. Using the supra-adventitia dissection plane, we were able to achieve total resections in four cases of complex intravagal paraganglioma. The surgical management of these cases was complex because of the following: 1) misdiagnosis as a carotid body tumor, 2) previous radiation therapy and surgical procedure, 3) association with glomus jugulare, and 4) a giant tumor with invasion of the temporal bone and encasement of the internal carotid artery. We report the surgical management of intravagal paragangliomas and the role of radiation therapy, hormonal secretion, and rehabilitation care.

Management of intracranial meningiomas secondarily involving the infratemporal fossa: radiographic characteristics, pattern of tumor invasion, and surgical implications.

OBJECTIVE: Intracranial meningiomas extending into the infratemporal fossa (ITF) are uncommon. This series describes the radiographic characteristics, histological pattern of invasion, and implications for surgical treatment of intracranial meningiomas. METHODS: Nine patients (median age, 52 yr) underwent resection of a transcranial meningioma extending into the ITF. Five patients (56%) had undergone a previous resection; however, none had involvement of the ITF. Four patients (44%) had received prior radiation therapy to the area. RESULTS: Preoperative neuroradiography uniformly showed erosion of the middle fossa floor and extension of the tumor through cranial base foramina. Histological results indicated tumor invasion of the middle fossa floor and skeletal muscle in all patients. Perineural invasion was present in four patients. Mucosal invasion was observed in six patients. A middle fossa/zygomatic approach provided access to the intra- and extracranial components of the tumor, as well as the cavernous sinus, ITF structures, paranasal sinuses, and nasopharynx. Reconstruction was performed using the temporalis muscle, which provides a vascularized flap between exposed mucosa and the carotid artery and intradural structures. A gross total resection was performed in seven patients (78%). Postoperative complications included soft tissue ischemia (one patient), worsening of preoperative cranial neuropathy (two patients), and lower extremity deep vein thrombosis (two patients). One patient died 2 months postoperatively from a pulmonary embolus. Two patients had recurrence of intracranial meningiomas extending into the ITF at 2 and 3 years postoperatively, necessitating further resection. CONCLUSION: Understanding the pertinent clinical and morphological aspects of meningioma transcranially involving the ITF is essential to surgical treatment of patients with this condition.

Venous consideration in petrosal approach: microsurgical anatomy of the temporal bridging vein.

OBJECTIVE: The technical difficulty of using the petrosal approach and the likelihood of encountering venous complications depend on the particular temporal venous anatomy. To reduce such potential risks, neurosurgeons must have adequate knowledge of the variations in the anatomy of the temporal venous drainage system, particularly of the temporal bridging veins. METHODS: In 20 cadaveric specimens, the temporal bridging veins were examined with the aid of an operating microscope. The anatomic location of their termination and of the tributaries of these bridging veins was noted. RESULTS: Forty-four terminations and 109 tributaries of the temporal bridging veins were identified in our specimens. The temporal bridging veins were divided into three groups according to the anatomic location of their terminations: 1) the transverse sinus group (seen in all 20 hemispheres), with drainage into the lateral part of the cerebellar tentorium, to which most of the vein of Labbé belongs; 2) the tentorial group (seen in 50% of the 20 hemispheres), with drainage into the medial part of the tentorium, which is composed mainly of the middle and posterior temporobasal veins; and 3) the petrosal group (seen in 55% of the 20 hemispheres), with entry around the superior petrosal sinus, which may limit mobility of the temporal lobe in the petrosal approach. On the basis of this anatomic information, we propose a new classification of the temporal venous drainage system and discuss the clinical implications of these findings. CONCLUSION: In planning the petrosal approach, great care should be taken not only with the vein of Labbé but also with the petrosal bridging veins. Knowledge of this venous anatomy can reduce venous complications during the lateral cranial base approach.

Bridging veins on the tentorial surface of the cerebellum: a microsurgical anatomic study and operative considerations.

OBJECTIVE: When using the median infratentorial supracerebellar approach, all or numerous bridging veins over the cerebellar surface must be sacrificed. Such sacrifice potentially causes cerebellar venous infarction, especially when excessive cerebellar retraction is applied. To prevent such potential complications, neurosurgeons must have adequate knowledge of the anatomy of the bridging veins, particularly the hemispheric bridging veins. METHODS: In 14 cadaveric specimens (26 sides), the number, locations, and tributaries of both the vermian and hemispheric bridging veins between the superior surface of the cerebellum and the tentorium were examined with the aid of an operating microscope. In addition, particular attention was given to the distribution patterns and collateral pathways of the hemispheric bridging veins. RESULTS: The average number of vermian bridging veins per cerebellum was 3.24. The average number of hemispheric bridging veins per side was 1.69, and they were most frequently located in the intermediate third of the hemisphere (59.0%). The distribution patterns of the hemispheric bridging veins were classified into six groups according to the draining patterns of each cerebellar hemisphere. Each hemispheric bridging vein usually had several collateral pathways between other draining veins. The most prominent collateral pathways of the hemispheric bridging veins frequently connected with the vermian bridging veins. CONCLUSION: Anatomic familiarity with the bridging veins can minimize their intraoperative sacrifice and avert subsequent postoperative complications. This knowledge also assists in planning the best approach to the pineal region.

Diaphragma sellae meningiomas.

Despite their unique clinical, radiological, and surgical considerations, diaphragma sellae meningiomas remain largely undistinguished from tuberculum sellae meningiomas. On the basis of our experience with 12 patients with diaphragma sellae meningiomas and our review of the literature, we classify these tumors into three groups: Type A, originating from the upper leaf of the diaphragma sellae anterior to the pituitary stalk; Type B, originating from the upper leaf of the diaphragma sellae posterior to the pituitary stalk; and Type C, originating from the inferior leaf of the diaphragma sellae. Each type has specific clinical symptoms. Type A mainly presents with unilateral visual disturbances and visual field defects resembling those of tuberculum sellae meningiomas, although preoperative diabetes insipidus occurred in patients with large tumors. Type B causes fewer visual disturbances, but memory disturbance and hypopituitarism occur. Type C closely resembles nonfunctioning pituitary adenomas; bitemporal hemianopsia and hypopituitarism are common. Multiplanar magnetic resonance images can accurately diagnose the tumor and establish its type. Surgical approaches include the cranio-orbital approach for Types A and B and the transcranial-transsphenoidal approach for Type C. Surgery is more difficult than for tuberculum sellae meningiomas because of the deep location and the difficulty of dissecting Types A and B from the pituitary stalk. Repair of the sphenoid sinus to prevent cerebrospinal fluid leakage is mandatory for Type C tumors.

Grade zero removal of supratentorial convexity meningiomas.

Although meningiomas are benign intracranial tumors, their frequency of recurrence after surgery has not been as low as expected. The recurrence rate of meningiomas is clearly related to the degree of tumor removal. Simpson Grade I removal, which entails excising the tumor and its dural and sinus attachments, is associated with the lowest rate of recurrence. To further minimize the recurrence of convexity meningiomas, we removed an additional dural margin of about 2 cm around the tumor (Grade 0 removal). For tumors involving bone, we removed the hyperostotic bone with a healthy margin and pericranium in en bloc resection. Between 1982 and 1992, 37 patients (15 men, 22 women) with an average age of 52.1 years were operated on by the above technique. Nineteen had a follow-up period of more than 5 years. To date, no tumors have recurred and no morbid incidences have occurred with this maneuver. We believe that the recurrence rate of convexity meningiomas can be diminished by including in the resection a margin of dura that might harbor a foci of tumor cells.

Hearing impairment resulting from a pineal region meningioma.

Because of extensive interconnections within the auditory pathways, hearing impairment from a central origin is rare. We describe a patient with a large pineal region meningioma in whom hearing loss was the predominant symptom. The patient promptly recovered hearing after the surgical removal of the tumor. The mechanism of this phenomenon is discussed.

The low incidence of cerebral aneurysms in the Middle East: is it a myth?

It is common belief that there is a relatively low incidence of cerebral aneurysm in the Middle East; however, there are neither routine autopsy studies nor reliable public health data to confirm this impression. We analyzed the clinical data of all patients admitted with a diagnosis of nontraumatic subarachnoid hemorrhage to the King Faisal Specialist Hospital, a modern tertiary medical center in Riyadh, Saudi Arabia. These data were compared with reports from other countries. Although environmental or inherited factors may predispose to a lower incidence of intracranial aneurysm in the Middle East, the true incidence is higher and is not apparent because of the previous referral system for medical care. Medical facilities and expertise are rapidly improving, and future studies undoubtedly will show a higher incidence of intracranial aneurysm.

Petrosal approach for petroclival meningiomas.

Thirteen patients harboring large petroclival meningiomas are reported. The evolution of the petrosal approach is discussed, and modifications for improvement in surgical technique are described. There was no mortality in this series, and total removal was achieved in all but two patients. Morbidity included cranial nerve deficit, pulmonary embolism, and hemiparesis.

Microsurgical removal of suprasellar meningiomas.

The authors report 17 cases of large suprasellar meningiomas operated on during the 2-year period from February 1982 through March 1984. The tumors ranged from 4 to 9 cm in diameter. These patients presented with severe visual loss (4 were blind) and optic atrophy or papilledema. These tumors were noteworthy in their encroachment against and around the carotid arteries and optic nerves laterally, as well as against the hypothalamus with extension into the interpeduncular cistern and frontal fossa. Advanced microsurgical technique assisted in total removal of all tumor tissue with preservation of vital structures. There were three deaths: two from pulmonary embolism and one from gastrointestinal hemorrhage. The surgical technique for the total removal of these very large tumors is described.

Shunt for bypass graft of the cavernous carotid artery: an anatomical and technical study.

During direct surgery of neoplastic and vascular lesions of the cavernous sinus, the intracavernous carotid artery may be injured beyond repair, or its total isolation may be necessary for surgical management of these lesions. The newly developed procedure of a saphenous vein graft bypass of the cavernous carotid artery allows re-establishment of carotid circulation. Patients with poor collateral circulation are at high risk for ischemic complications induced by the prolonged temporary occlusion required to perform the bypass graft. Optimal management of these patients is to perform the venous bypass graft for permanent vascularization while maintaining carotid cerebral circulation through an intraoperative shunt. We studied this procedure in cadavers, and three shunt types were evaluated: the external intrapetrous-supraclinoid shunt (Type A), the internal intrapetrous-supraclinoid shunt (Type B), and the neck internal carotid-supraclinoid shunt (Type C). Anatomical landmarks, techniques, distances, caliber, and materials used are presented. The rationale and candidates for such a procedure are discussed. The specifications of an optimal balloon shunt are presented, and the three procedures are compared.

En bloc resection of an ethmoid carcinoma involving the orbit and medial wall of the cavernous sinus.

The involvement of the cavernous sinus by malignant tumors has limited their surgical treatment. We report here a successful en bloc resection of an invasive ethmoid carcinoma involving the cavernous sinus in a 46-year-old man. To prepare for surgery on this patient, a cadaver study was performed to investigate the feasibility of en bloc cavernous sinus resection and reconstruction. The preoperative evaluation, operative approach, and postoperative management are presented.

An orbitocranial approach to complex aneurysms of the anterior circulation.

A surgical approach to the skull base was developed in cadavers and then used in the treatment of patients with complex aneurysms of the anterior circulation. The operative method involves removal of portions of the orbital rim, orbital roof, and sphenoid bone. By removing the orbital rim and a portion of the orbital roof, multidirectional viewing is possible. This is important when dealing with the anterior aspect of the cavernous sinus and anterior clinoid process, as must frequently be done when isolating the neck of an ophthalmic aneurysm. The optic canal is opened wide and the optic nerve mobilized, allowing resection of the dura propria covering the cavernous carotid artery. Clip placement is performed in an anteroposterior plane, thus lessening the chance for compromise of the internal carotid artery. The low approach alleviates brain retraction and the small flap minimizes brain exposure. The approach also allows preservation of the arterial and neural supply to the frontalis and temporalis muscles, thereby preventing postoperative cosmetic deficits. During the past year and a half, this approach has been employed in 25 patients with difficult aneurysms of the anterior circulation. The difficulties of these cases stemmed from their odd location, size, or complex anatomy. Although periorbital edema may have been more severe during the first postoperative week, overall improved cosmesis was achieved.

Fiber dissection technique: lateral aspect of the brain.

OBJECTIVE: The fiber dissection technique involves peeling away the white matter tracts of the brain to display its three-dimensional anatomic organization. Early anatomists demonstrated many tracts and fasciculi of the brain using this technique. The complexities of the preparation of the brain and the execution of fiber dissection have led to the neglect of this method, particularly since the development of the microtome and histological techniques. Nevertheless, the fiber dissection technique is a very relevant and reliable method for neurosurgeons to study the details of brain anatomic features. METHODS: Twenty previously frozen, formalin-fixed human brains were dissected from the lateral surface to the medial surface, using the operating microscope. Each stage of the process is described. The primary dissection tools were handmade, thin, wooden spatulas with tips of various sizes. RESULTS: We exposed and studied the myelinated fiber bundles of the brain and acquired a comprehensive understanding of their configurations and locations. CONCLUSION: The complex structures of the brain can be more clearly defined and understood when the fiber dissection technique is used. This knowledge can be incorporated into the preoperative planning process and applied to surgical strategies. Fiber dissection is time-consuming and complex, but it greatly adds to our knowledge of brain anatomic features and thus helps improve the quality of microneurosurgery. Because other anatomic techniques fail to provide a true understanding of the complex internal structures of the brain, the reestablishment of fiber dissection of white matter as a standard study method is recommended.