Craniofacial disassembly in the management of skull-base tumors

Craniofacial disassembly now plays a major role in the management of tumors that invade the skull base. The chief advantage of this technique is the greatly improved operative exposure it provides, allowing the surgeon to resect such tumors more completely and with an added margin of safety. Microneurosurgical advances have made it possible to preserve cranial nerve function in many cases, and modern reconstructive methods employing vascularized flaps have helped to reduce postoperative complications and deformity. Through the combination of craniofacial techniques and oncologic principles, the outlook for patients with skull base tumors is improving.

Aneurysms of the intracavernous carotid artery: a multidisciplinary approach to treatment

Of 43 cavernous sinus aneurysms diagnosed over 6 1/2 years, 23 fulfilled indications for treatment; of these 19 were treated, eight surgically and 11 with interventional radiological techniques. Six small and two giant aneurysms were treated surgically: four were clipped, two were repaired primarily, and two were trapped with placement of a saphenous-vein bypass graft. Seven large and four giant aneurysms were treated with interventional radiological techniques: in five cases the proximal internal carotid artery (ICA) was sacrificed; one aneurysm was trapped with detachable balloons; and five were embolized with preservation of the ICA lumen. The mean follow-up period was 25 months. At follow-up examination, three patients in the surgical group were asymptomatic, two had improved, and three had worsened. Three of these patients had asymptomatic infarctions apparent on computerized tomography (CT) scans. At follow-up examination, four radiologically treated patients were asymptomatic, five had improved, two were unchanged, and none had worsened. One patient had asymptomatic and one minimally symptomatic infarction apparent on CT scans; both lesions were embolic foci after aneurysm embolization with preservation of the ICA. It is concluded that treatment risk depends more on the adequacy of collateral circulation than on the size of the aneurysm. A multidisciplinary treatment protocol for these aneurysms is described, dividing patients into high-, moderate-, and low-risk groups based on pretreatment evaluation of the risk of temporary or permanent ICA occlusion using a clinical balloon test occlusion coupled with an ICA-occluded stable xenon/CT cerebral blood flow study. Radiological techniques are suggested for most low-risk patients, while direct surgical techniques are proposed for most moderate- and high-risk patients.

Intraoperative Electrophysiological Monitoring of the Facial Nerve in the Presence of Damage to the Pre-Parotid Segment

A method is described for obtaining intraoperative monitoring of facial nerve function in patients who have previously lost facial nerve function distal to the pes anserinus or who have absent function because of trauma to the facial nerve in the pre-parotid segment during operative exposure.

Surgical management of anteriorly placed lesions at the craniocervical junction--an alternative approach

Lesions ventral to the neuraxis at the craniocervical junction can pose a significant management problem because of their strategic location. Conventional posterolateral approaches sometimes may not permit adequate visualization of the entire base of the tumor without significant manipulation of the brain stem and spinal cord. The anterior transoral and extrapharyngeal approaches are alternate ways of exposing this region without neural retraction. However, these approaches do not provide adequate exposure of the lateral margins of the tumour, there is no control of the vertebral arteries and cranial nerves and the tumor--brain stem interface is not seen till the end of the operation. A lateral approach is described in this report which involves additional bone removal in the region of the mastoid process and the articular pillars in order to provide a true lateral perspective for the removal of these tumors. The advantages include excellent definition of the interface between the tumor and cord/brain stem without manipulation of the neuraxis, control of the ipsilateral vertrebral artery and caudal cranial nerves, ability to remove the intra- and extradural portions of the tumor in one operation and the ability to perform an immediate bony fusion if necessary. The application of this approach in the management of 9 patients with a variety of intra- and extradural lesions at the clivus and foramen magnum is discussed.

Surgical management of clival meningiomas

The surgical management of intradural clival tumours is difficult due to the relative inaccessibility of the clivus through traditional neurosurgical approaches, and the intimate relationship of such tumours to critical neurovascular and brainstem structures. This report concentrates on the experience with clival meningiomas, which are the most common intradural clival tumours. Between July 1983 and July 1990, 52 patients with petroclival meningiomas underwent surgical excision of their tumours. A variety of skull base approaches were utilized to obtain wide tumour exposure with minimal brain retraction. Large or giant tumours required multiple approaches and staged removal of tumour. Tumour resection was evaluated by a standard protocol of postoperative MR or CT scans. Total tumour resection was achieved in 38 cases (73%), subtotal resection in 11 (21%) and partial resection in 3 (6%). Follow-up has ranged from 4 to 83 months. Two patients had recurrence of tumour requiring re-operation with one receiving additional external beam radiation. Two postoperative deaths occurred, one from pneumonia and another from infectious complications. The most common postoperative morbidity were lower cranial nerve palsy, aspiration peumonia and temporary hemiparesis.

Management of tumours involving the cavernous sinus

The operative experience with 137 tumours of the cavernous sinus at the University of Pittsburgh during the past 7 years is reported. The importance of the normal and tumour-infiltrated cavernous sinus anatomy and imaging is delineated. 63% of the tumours are benign, primarily meningiomas, for which an anatomical grading system is presented. The various operative approaches to the cavernous sinus are described. 88% of the meningiomas were totally resected. There was a 1.5% operative mortality and 1.5% severe morbidity rate. Initial ipsilateral opthalmoplegia progressively improved in the majority of patients. For all patients with at least 6 months of follow up of benign tumours, the intracavernous tumour recurrence rate was 3% and total recurrence rate was 6%.

Extradural petrous bone and petroclival neoplasms

Extradural petroclival tumours are composed of a spectrum of histological and anatomical configurations dictating a variety of surgical approaches. The experience with 68 such tumours operated at the University of Pittsburgh is presented, emphasizing the basal subfrontal and lateral approaches. 85% of these tumours are benign or low-grade malignancies, with 62% of these totally resected, resulting in a 5.4% recurrence rate. The operative mortality was 1.5% and major morbidity 3%. Well-planned surgery based on precise anatomical knowledge and imaging is the basis of treatment for petroclival tumours.

Chondromyxoid fibromas of the neurocranium

We report a case of a chondromyxoid fibroma involving the upper clivus in a 73-year-old man. Chondromyxoid fibromas are uncommon benign bone tumors that rarely involve the skull. Chondromyxoid fibromas arising in the membranous neurocranium resemble their extracranial counterparts, appearing as radiolucent lesions with sclerotic margins and presenting most often as a painless focal swelling. Chondromyxoid fibromas arising in the chondrocranium differ from their extracranial counterparts and from those arising in the membranous neurocranium. They appear as locally destructive, often calcified, and exophytic lesions without sclerotic margins and present with cranial nerve dysfunction and symptoms caused by central nervous system compression.

Intracranial Hemorrhage from Aneurysms and Arteriovenous Malformations during Pregnancy and the Puerperium

Intracranial hemorrhage (ICH) from an intracranial aneurysm or arteriovenous malformation is a grave complication of pregnancy and is responsible for 5 to 12% of all maternal deaths. We critically analyzed 154 cases of verified ICH during pregnancy from an identified intracranial lesion, including 2 patients treated at our institution and 152 cases previously reported in the literature in English. Aneurysms were responsible for ICH in 77% of patients, and arteriovenous malformations in 23%. Hemorrhage occurred antepartum in 92% of patients and postpartum in 8%. Women with angiomatous hemorrhage were younger than those with aneurysmal hemorrhage; however, in contrast to previous reports, we found no differences between angiomatous and aneurysmal hemorrhage with respect to parity or gestational age at the time of the initial hemorrhage. Hypertension and/or albuminuria were present at some time during the pregnancy in 34% of patients with documentation, which sometimes made it difficult to differentiate angiomatous or aneurysmal ICH from that associated with eclampsia. In a logistic regression analysis, surgical management of aneurysms, but not arteriovenous malformations, was associated with significantly lower maternal and fetal mortality, independent of other covariants. For those patients with a lesion not operated on, cesarean delivery afforded no better maternal or fetal outcome than did vaginal delivery. We conclude that the decision to operate after ICH during pregnancy should be based upon neurosurgical principles, whereas the method of delivery should be based upon obstetrical considerations. The perioperative and anesthetic management of the pregnant patient with a neurosurgical complication is discussed.

Intracranial hemorrhage from aneurysms and arteriovenous malformations during pregnancy and the puerperium

Intracranial hemorrhage (ICH) from an intracranial aneurysm or arteriovenous malformation is a grave complication of pregnancy and is responsible for 5 to 12% of all maternal deaths. We critically analyzed 154 cases of verified ICH during pregnancy from an identified intracranial lesion, including 2 patients treated at our institution and 152 cases previously reported in the literature in English. Aneurysms were responsible for ICH in 77% of patients, and arteriovenous malformations in 23%. Hemorrhage occurred antepartum in 92% of patients and postpartum in 8%. Women with angiomatous hemorrhage were younger than those with aneurysmal hemorrhage; however, in contrast to previous reports, we found no differences between angiomatous and aneurysmal hemorrhage with respect to parity or gestational age at the time of the initial hemorrhage. Hypertension and/or albuminuria were present at some time during the pregnancy in 34% of patients with documentation, which sometimes made it difficult to differentiate angiomatous or aneurysmal ICH from that associated with eclampsia. In a logistic regression analysis, surgical management of aneurysms, but not arteriovenous malformations, was associated with significantly lower maternal and fetal mortality, independent of other covariants. For those patients with a lesion not operated on, cesarean delivery afforded no better maternal or fetal outcome than did vaginal delivery. We conclude that the decision to operate after ICH during pregnancy should be based upon neurosurgical principles, whereas the method of delivery should be based upon obstetrical considerations. The perioperative and anesthetic management of the pregnant patient with a neurosurgical complication is discussed.

Meningiomas involving the clivus: a six-year experience with 41 patients

A series of 41 meningiomas involving the clivus operated on from July 1983 to January 1990 is reported. The presenting symptoms and signs of these patients were similar to those reported previously. All the patients were evaluated by pre- and postoperative thin-section, high-resolution computed tomography using soft tissue and bone algorithms. Most of the patients also underwent magnetic resonance imaging. The regions of the clivus involved by tumor were divided into upper, middle, or lower regions on the basis of anatomical landmarks. The diameter of the tumor was measured in three axes, and a tumor volume and a tumor equivalent diameter were computed to categorize tumors as small, medium, large, or giant types. There were 9 medium, 27 large, and 5 giant tumors in this series. Some simple and some complex operative approaches were employed to effect tumor removal. Large and giant tumors often required more than one operative approach to remove the tumor. Intraoperative technical difficulties included tumor consistency, vascularity, dissection from the brain stem, and vascular and cranial nerve encasement. Postoperative computed tomographic scans documented total excision in 32 patients (78%). Residual tumor remained in the clival or cavernous sinus areas. These patients were either being observed, or were treated with gamma knife radiosurgery. There was one operative death due to pneumonia (2%), and three patients (7%) suffered permanent major neurological changes, presumably due to vascular occlusions in the posterior circulation. In the follow-up period, which ranged from 3 to 76 months, 2 patients (6%) with tumors that had appeared to be totally excised experienced recurrence. These patients were treated by a second operation, alone or in combination with radiation therapy. Two patients who had subtotal excisions (25%) had evidence of regrowth. In 2 patients, tumor growth continued despite gamma knife radiosurgery or external beam radiotherapy.

Meningiomas Involving the Clivus: A Six-Year Experience with 41 Patients

A series of 41 meningiomas involving the clivus operated on from July 1983 to January 1990 is reported. The presenting symptoms and signs of these patients were similar to those reported previously. All the patients were evaluated by preand postoperative thin-section, high-resolution computed tomography using soft tissue and bone algorithms. Most of the patients also underwent magnetic resonance imaging. The regions of the clivus involved by tumor were divided into upper, middle, or lower regions on the basis of anatomical landmarks. The diameter of the tumor was measured in three axes, and a tumor volume and a tumor equivalent diameter were computed to categorize tumors as small, medium, large, or giant types. There were 9 medium, 27 large, and 5 giant tumors in this series. Some simple and some complex operative approaches were employed to effect tumor removal. Large and giant tumors often required more than one operative approach to remove the tumor. Intraoperative technical difficulties included tumor consistency, vascularity, dissection from the brain stem, and vascular and cranial nerve encasement. Postoperative computed tomographic scans documented total excision in 32 patients (78%). Residual tumor remained in the clival or cavernous sinus areas. These patients were either being observed, or were treated with gamma knife radiosurgery. There was one operative death due to pneumonia (2%), and three patients (7%) suffered permanent major neurological changes, presumably due to vascular occlusions in the posterior circulation. In the follow-up period, which ranged from 3 to 76 months, 2 patients (6%) with tumors that had appeared to be totally excised experienced recurrence. These patients were treated by a second operation, alone or in combination with radiation therapy. Two patients who had subtotal excisions (25%) had evidence of regrowth. In 2 patients, tumor growth continued despite gamma knife radiosurgery or external beam radiotherapy.

Facial translocation: a new approach to the cranial base

Nasopharynx, clivus, and cavernous sinus are difficult regions of the cranial base in which to perform oncologic surgery. We have developed an approach to this area by using facial soft tissue translocation and craniofacial osteotomies. Surgical field obtained at the skull base can extend from the contralateral eustachian tube to ipsilateral geniculate ganglion. It includes the nasopharynx, clivus, sphenoid, and cavernous sinus, as well as the entire infratemporal fossa and superior orbital fissure. Our experience with this technique in 12 patients is reported. All patients healed primarily.

The subtemporal and preauricular infratemporal approach to intradural structures ventral to the brain stem

The subtemporal and preauricular infratemporal operative technique is an approach to the skull base through the anterior portion of the petrous temporal bone and is used for the removal of predominantly extradural tumors in this region. The present study, based on dissection of human cadavers, describes the use of this approach for the management of intradural lesions in the region of the clivus. Its main advantages include avoidance of brain retraction, the use of an extrapharyngeal route, and exposure of the ventral aspect of the pons and medulla and related structures caudal to the trigeminal root. This approach can easily be combined with an intradural subtemporal approach to provide additional exposure of the superior clivus rostral to the trigeminal root. Combining the two approaches provides direct access to the ventral surface of the entire brain stem from the dorsum sellae to the hypoglossal foramina. Five patients with lesions in the clivus and petrous apex have been operated on via this approach. Details of the anatomical aspects of the approach and its applications are presented.

An Extreme Lateral Approach to Intradural Lesions of the Cervical Spine and Foramen Magnum

Meningiomas and neurofibromas are the most common intradural extramedullary tumors of the foramen magnum and cervical spine. Many of these tumors are located ventral or ventrolateral to the spinal cord and medulla. Posterior approaches, although adequate for the management of most of these tumors, can sometimes result in incomplete removal of the tumor and exacerbation of the neurological deficits. Although the transoral and transcervical approaches provide a direct route to the tumor, the exposure of the lateral margins in the case of large tumors is inadequate. In addition, because of the removal of vertebral bodies, subsequent fusion may be necessary. In the present report, an extreme lateral approach to the foramen magnum and cervical spine for the removal of intradural tumors is described. The approach provides a lateral exposure of the tumor-cord/stem interface, thus permitting safe dissection without retraction of the cord. The entire longitudinal and lateral extent of the tumor and also its extradural extension can be can be managed by this approach. This approach can be considered in such a group of patients harboring entirely ventral or recurrent tumors for which the conventional posterior approach has failed. Six patients who underwent this procedure are described to illustrate its application.

An extreme lateral approach to intradural lesions of the cervical spine and foramen magnum

Meningiomas and neurofibromas are the most common intradural extramedullary tumors of the foramen magnum and cervical spine. Many of these tumors are located ventral or ventrolateral to the spinal cord and medulla. Posterior approaches, although adequate for the management of most of these tumors, can sometimes result in incomplete removal of the tumor and exacerbation of the neurological deficits. Although the transoral and transcervical approaches provide a direct route to the tumor, the exposure of the lateral margins in the case of large tumors is inadequate. In addition, because of the removal of vertebral bodies, subsequent fusion may be necessary. In the present report, an extreme lateral approach to the foramen magnum and cervical spine for the removal of intradural tumors is described. The approach provides a lateral exposure of the tumor-cord/stem interface, thus permitting safe dissection without retraction of the cord. The entire longitudinal and lateral extent of the tumor and also its extradural extension can be can be managed by this approach. This approach can be considered in such a group of patients harboring entirely ventral or recurrent tumors for which the conventional posterior approach has failed. Six patients who underwent this procedure are described to illustrate its application.

Acoustic recordings from experimental saccular aneurysms in dogs

In an effort to isolate and characterize the emission of acoustic signals from saccular aneurysms, we made a series of invasive microphone recordings from experimental aneurysms created on the common carotid arteries of dogs using the vein pouch technique. Using a modified probe microphone, we compared recordings from the common carotid artery before creation of the aneurysm to recordings from the aneurysmal surface, both before and after clip occlusion. We then performed spectral analysis, band-pass filtering, and spectrographic analysis to compare the dominant frequency and width of the frequency range of both the aneurysmal and carotid recorded signals. The aneurysmal signals had a significantly higher dominant frequency (p less than or equal to 0.05) and a significantly wider frequency range (p less than or equal to 0.05) than the carotid signals. Aneurysmal signals recorded under conditions of systemic hypotension had a significantly lower frequency (p less than or equal to 0.05) than aneurysmal signals recorded under conditions of hypertension. Our results support the assumptions that acoustic signals from experimental saccular aneurysms are distinct from those of the parent vessel and that the aneurysmal signal can be characterized using passive microphone recordings.

Anterior cranial base reconstruction: role of galeal and pericranial flaps

Reconstruction of surgical defects in 30 patients undergoing surgery of the anterior cranial base was performed using pericranial, galeopericranial, and galeal scalp flaps. Twenty-seven patients had resection of neoplasms, the majority of which were malignant. Fifty-seven percent of patients received prior therapy consisting of surgery and/or radiotherapy. Adequate healing of the cranial base was noted in all cases without persistent cerebrospinal fluid leaks, meningitis, or brain herniation. Mucosalization of the intranasal surface was noted. No skin grafts were used. At a median follow-up of 13 months, 67% of patients were alive with no evidence of disease. The pericranial, galeopericranial, and galeal flaps are highly reliable, versatile, and well suited for reconstruction of the anterior cranial base.

Aneurysms of the Intracavernous Carotid Artery: Natural History and Indications for Treatment

Of 37 patients with 44 intracavernous carotid artery aneurysms (ICCAAns) diagnosed between 1976 and 1988. patients with 20 aneurysms were followed without treatment for 5 months to 13 years (median, 2.4 years). Ten of the 20 ICCAAns were asymptomatic at diagnosis, and 10 were symptomatic. Three of the asymptomatic ICCAAns were symptomatic at follow-up. One of these required clipping because of a progressing cavernous sinus syndrome; the other 2 were minimally symptomatic and have not required treatment. Of the 10 initially symptomatic ICCAAns, 2 had not changed, 4 became more symptomatic, and 4 had symptomatically improved by follow-up. One patient with an ICCAAn that had not changed clinically was lost to follow-up 6 months after diagnosis. Of the 4 ICCAAns that became more symptomatic, 2 continue to be monitored, and 2 required intervention; one with detachable balloon occlusion of the aneurysm with preservation of the internal carotid artery lumen, and the other with gradual cervical internal carotid artery occlusion. The clinical course of this selected group of patients with ICCAAns suggests that the natural history of ICCAAns can be quite variable. Although clinical progression does occur, symptomatic ICCAAns also can improve spontaneously. Therapeutic intervention for asymptomatic ICCAAns should be reserved for patients with aneurysms arising at the anterior genu of the carotid siphon and/or extending into the subarachnoid space, where subarachnoid hemorrhage is most likely. Intervention for symptomatic ICCAAns should be reserved for patients with subarachnoid hemorrhage, epistaxis, severe facial or orbital pain, evidence of radiographic enlargement, progressive ophthalmoplegia, or progressive visual loss.

Aneurysms of the intracavernous carotid artery: natural history and indications for treatment

Of 37 patients with 44 intracavernous carotid artery aneurysms (ICCAAns) diagnosed between 1976 and 1988, patients with 20 aneurysms were followed without treatment for 5 months to 13 years (median, 2.4 years). Ten of the 20 ICCAAns were asymptomatic at diagnosis, and 10 were symptomatic. Three of the asymptomatic ICCAAns were symptomatic at follow-up. One of these required clipping because of a progressing cavernous sinus syndrome; the other 2 were minimally symptomatic and have not required treatment. Of the 10 initially symptomatic ICCAAns, 2 had not changed, 4 became more symptomatic, and 4 had symptomatically improved by follow-up. One patient with an ICCAAn that had not changed clinically was lost to follow-up 6 months after diagnosis. Of the 4 ICCAAns that became more symptomatic, 2 continue to be monitored, and 2 required intervention: one with detachable balloon occlusion of the aneurysm with preservation of the internal carotid artery lumen, and the other with gradual cervical internal carotid artery occlusion. The clinical course of this selected group of patients with ICCAAns suggests that the natural history of ICCAAns can be quite variable. Although clinical progression does occur, symptomatic ICCAAns also can improve spontaneously. Therapeutic intervention for asymptomatic ICCAAns should be reserved for patients with aneurysms arising at the anterior genu of the carotid siphon and/or extending into the subarachnoid space, where subarachnoid hemorrhage is most likely. Intervention for symptomatic ICCAAns should be reserved for patients with subarachnoid hemorrhage, epistaxis, severe facial or orbital pain, evidence of radiographic enlargement, progressive ophthalmoplegia, or progressive visual loss.

Operative treatment of intracranial epidermoid cysts and cholesterol granulomas: report of 21 cases

Thirteen patients had operations to remove intracranial epidermoid cysts, and long-term follow-up was obtained. Total or nearly total tumor and capsule removal was accomplished in 7 patients during the initial operation. This group required no additional operations. The other 6 underwent subtotal tumor removal and required multiple operations for symptomatic tumor recurrence. This latter group had a poorer neurological outcome. We conclude that initial total or near-total tumor resection is highly desirable in treating intracranial epidermoid cysts, particularly in physiologically young individuals. Five patients were followed after operations to remove pure cholesterol granulomas of the petroclival bone, and 3 additional patients were followed after operations to remove tumors with combined histopathological features of both an epidermoid cyst and cholesterol granuloma. Four patients with some component of a cholesterol granuloma had concurrent middle ear infections, and 4 did not. Intracranial subtotal excision and drainage of these lesions was the initial operative management in 7 patients, 5 of whom have required multiple operations for symptomatic tumor recurrence. Therefore, we conclude that subtotal excisional procedures for tumors with histopathological features of cholesterol granulomas are not usually successful in establishing long-term cures. Total excision, as recommended for epidermoid cysts, tumors frequently confused with cholesterol granulomas when occupying the petroclival region, may be warranted for these tumors as well. We postulate that when a congenital epidermoid cyst occurs in the petroclival bone, it may incite a local inflammatory reaction, producing lesions which have the histological features of both epidermoid cysts and cholesterol granulomas.

Operative Treatment of Intracranial Epidermoid Cysts and Cholesterol Granulomas: Report of 21 Cases

Thirteen patients had operations to remove intracranial epidermoid cysts, and long-term follow-up was obtained. Total or nearly total tumor and capsule removal was accomplished in 7 patients during the initial operation. This group required no additional operations. The other 6 underwent subtotal tumor removal and required multiple operations for symptomatic tumor recurrence. This latter group had a poorer neurological outcome. We conclude that initial total or near-total tumor resection is highly desirable in treating intracranial epidermoid cysts, particularly in physiologically young individuals. Five patients were followed after operations to remove pure cholesterol granulomas of the petroclival bone, and 3 additional patients were followed after operations to remove tumors with combined histopathological features of both an epidermoid cyst and cholesterol granuloma. Four patients with some component of a cholesterol granuloma had concurrent middle ear infections, and 4 did not. Intracranial subtotal excision and drainage of these lesions was the initial operative management in 7 patients. 5 of whom have required multiple operations for symptomatic tumor recurrence. Therefore, we conclude that subtotal excisional procedures for tumors with histopathological features of cholesterol granulomas are not usually successful in establishing long-term cures. Total excision, as recommended for epidermoid cysts, tumors frequently confused with cholesterol granulomas when occupying the petroclival region, may be warranted for these tumors as well. We postulate that when a congenital epidermoid cyst occurs in the petroclival bone, it may incite a local inflammatory reaction, producing lesions which have the histological features of both epidermoid cysts and cholesterol granulomas.

A new method to predict safe resection of the internal carotid artery

A patent internal carotid artery (ICA) is essential in most patients. Management of skull base lesions often requires translocation, balloon embolization, or resection of this vessel. Preoperative tests to assess the availability of collateral flow have not been uniformly accurate. A new test that significantly increases the safety of surgical removal of the ICA is described. One hundred thirty-six patients were studied with temporary balloon occlusion (TBO) of the ICA and determination of stable xenon-enhanced computed tomography cerebral blood flow (Xe/CT CBF) measurements. Eleven patients failed TBO and were determined to be at very high risk of stroke with loss of the ICA. Ninety-six of the patients were predicted to be at minimal risk with permanent loss of the ICA by Xe/CT CBF studies. Twenty-one patients in this group had either permanent balloon occlusion (PBO) or surgical resection of the ICA with no permanent neurologic sequelae. Our studies show that the combination of preoperative TBO and Xe/CT CBF studies significantly increases the safety of ICA resection.

Malignant skull base tumors

A multidisciplinary approach to the treatment of malignant cranial base tumors has resulted in improved resections with less morbidity and a greater potential for cure. An improved understanding of the complex anatomy has allowed the development of new surgical approaches and improved methods of reconstruction. The authors' experience with the treatment of malignant neoplasms of the cranial base is reviewed, with emphasis on biologic behavior of this diverse group of neoplasms.

Saphenous vein graft bypass of the cavernous internal carotid artery

Saphenous vein graft reconstruction was performed from the petrous to the supraclinoid internal carotid artery (ICA) to replace the cavernous ICA in six patients during direct intracavernous operations. Four of these patients had intracavernous neoplasms with invasion of the ICA and two had intracavernous ICA aneurysms that could not be clipped or occluded with intraluminal balloons. All but one patient had evidence of poor collateral flow reserve in a balloon occlusion test of the ICA. The superficial temporal artery was not present in four patients, was minuscule in one, and was damaged during the initial dissection in another, making it unsuitable for superficial temporal-to-middle cerebral artery branch anastomosis. Blood flow within the graft could not be established intraoperatively in one patient (who had excellent collateral circulation) due to the small size of the vein (3 mm). In all others, the grafts were patent on follow-up arteriography and transcranial Doppler studies. Three patients who had severe reduction of cerebral blood flow during test occlusion of the ICA exhibited temporary hemispheric neurological deficits postoperatively; the deficits were related to the duration of temporary ICA occlusion. All three recovered completely without evidence of infarction on computerized tomography (CT). One patient who clinically could not tolerate the balloon occlusion test of the ICA also had temporary neurological deficits with good recovery but showed evidence of border-zone infarction on CT scans. The present role of saphenous vein graft bypass of the cavernous ICA is discussed.

Aneurysms of the intracavernous carotid artery: clinical presentation, radiographic features, and pathogenesis

Thirty-seven patients with 44 intracavernous carotid artery aneurysms (ICCAAns) were seen at one institution from 1976 through 1988. Fifteen patients had multiple intracranial aneurysms and 7 had bilateral ICCAAns. Age at diagnosis ranged from 15 to 80 (median 61). Thirty patients were women. Sixteen had a history of hypertension. In 34% of patients the ICCAAns were asymptomatic at diagnosis, 36% were associated with headache, and 57% had associated signs or symptoms of mass effect including sixth nerve paresis (43%), trigeminal pain or sensory loss (32%), third nerve paresis (20%), decreased vision or visual field cut (18%), fourth nerve paresis (16%), and Horner's syndrome (7%). In 4 patients the ICCAAns ruptured, leading to subarachnoid hemorrhage in 3 and epistaxis in 1. Two patients with ICCAAns were seen with spontaneous thrombosis of the ipsilateral internal carotid artery leading to distal ischemic symptoms in 1. More than 90% of the ICCAAns were saccular. Thirty-four percent were small (less than 1 cm), 48% were large (1 to 2.5 cm), and 16% were giant (greater than 2.5 cm). The majority arose from the anterior genu of the intracavernous internal carotid artery, followed in frequency by the horizontal segment, and then the posterior genu. Magnetic resonance imaging is superior to computed tomography for diagnosing ICCAAns and is the screening procedure of choice. Angiography remains the "gold standard" for diagnosis and determining specific anatomic details necessary to plan therapy. Analyzing the radiographic anatomy of 44 ICCAAns. we conclude that theories attributing the origin of aneurysms to arterial bifurcations may be inadequate to explain the point of origin and direction of take off of up to one-fourth of ICCAAns.

Chordoma and chondrosarcoma of the cranial base: an 8-year experience

Between 1980 and 1988, 8 patients with chordomas and 9 with low-grade chondrosarcomas involving the cranial base were treated. All the patients were investigated preoperatively and postoperatively with computed tomographic or magnetic resonance imaging scans, according to a standard protocol. The tumors and the involved bony structures were surgically removed in one or more operations using different operative approaches. Ten patients underwent postoperative radiation therapy, either at our institution or prior to their referral to us. Total removal was defined as the absence of identifiable tumor on magnetic resonance imaging or computed tomographic obtained 3 months postoperatively, and was accomplished in 9 patients. The ability to achieve total removal was greatly increased in patients with tumors that had not previously been operated on. We believe that these tumors must be treated by aggressive surgical resection when initially diagnosed, and this can be accomplished with low morbidity. The follow-up period in our patients was too short to allow us to determine whether such total removals can result in a cure or in long-term control of these formidable tumors.

Chordoma and Chondrosarcoma of the Cranial Base: An 8-Year Experience

Between 1980 and 1988, 8 patients with chordomas and 9 with low-grade chondrosarcomas involving the cranial base were treated. All the patients were investigated preoperatively and postoperatively with computed tomographic or magnetic resonance imaging scans, according to a standard protocol. The tumors and the involved bony structures were surgically removed in one or more operations using different operative approaches. Ten patients underwent postoperative radiation therapy, either at our institution or prior to their referral to us. Total removal was defined as the absence of identifiable tumor on magnetic resonance imaging or computed tomographic obtained 3 months postoperatively, and was accomplished in 9 patients. The ability to achieve total removal was greatly increased in patients with tumors that had not previously been operated on. We believe that these tumors must be treated by aggressive surgical resection when initially diagnosed, and this can be accomplished with low morbidity. The follow-up period in our patients was too short to allow us to determine whether such total removals can result in a cure or in long-term control of these formidable tumors.

Neurilemomas of the trigeminal nerve

Sixteen patients with trigeminal neurilemoma have been treated at the University Health Center of Pittsburgh during the last 15 years. Two patients had middle fossa tumors arising from the trigeminal ganglion, four had posterior fossa tumors arising from the trigeminal roots, six had "hourglass" lesions extending above and below the tentorium and involving the trigeminal ganglion and its roots, and four had tumors arising from the trigeminal branches and extending through the superior orbital fissure, foramen rotundum, or foramen ovale. In seven patients, tumor had also invaded the cavernous sinus. The clinical and radiographic features of these tumors, the operative approaches employed, and the postoperative outcome are discussed. Complete tumor excision was achieved in 12 patients; all 12 remain free of recurrence 3 to 157 months after surgery. In contrast, all four patients who underwent subtotal tumor excision showed progressive neurological deterioration from regrowth of residual tumor within 3 years of the initial surgery. Two of these four subsequently had total tumor excision and both are disease-free 23 and 34 months after the second procedure. Major morbidity developed in only one of the 16 patients. There were no operative deaths. Nine patients had preserved or improved trigeminal function after treatment.

Surgical management of cranial base tumors: a report on 91 patients

Most cranial base tumors are now treatable by surgery because of recent advances, including the precision of modern diagnostic and interventional radiology. In the past two years, the authors have treated 91 patients with tumors involving the cranial base; over 60% were malignant. Most patients underwent a combined intracranial-extracranial procedure for tumor removal with immediate reconstruction. The complication rate was under 10% and most patients (more than 80%) are tumor-free in follow-up of 2-24 months. While cranial base surgery is now established as a field of surgical oncology, its true benefit to patients with tumors in this location, measured in five and 10-year tumor-free survival, cannot yet be determined.

The pathology of metastatic cardiac myxoma

The authors describe a case of a "benign" cardiac myxoma with metastases to a previously unreported site, the right temporal bone. The cardiac tumor became evident five years after the bone tumor presentation. Patients with myxomas in unusual locations should have a complete cardiac evaluation.

Cardiac myxoma metastatic to the temporal bone

Two metastases from an atrial myxoma occurred in the right common carotid artery distribution of a 34-year-old man. One metastasis caused the phenomenon of intracranial pseudoaneurysm in a distal branch of the middle cerebral artery. The other resulted in the unusual radiographic appearance of a tremendous, "bubbly" expansion of the temporal bone.

Surgical treatment of intracavernous neoplasms: a four-year experience

Forty-two patients with neoplasms involving the cavernous sinus had operations between 1983 and 1987. The lesions included 25 benign tumors (e.g., meningioma, neurilemoma) and 17 malignant tumors (e.g., chondrosarcoma, adenoid cystic carcinoma). The cavernous sinus was entered by inferior, anterolateral, or medial extradural approaches or by superior or lateral intradural approaches. The intracavernous internal carotid artery was managed by dissecting tumor away from it or by occlusion and excision with or without direct vein graft reconstruction, based on the results of a preoperative balloon occlusion test. Cranial nerves III, IV, V, and VI usually were dissected from tumor, but in 3 cases of tumor invasion, the excised nerve segment was reconstructed by direct suture or with a sural nerve interposition graft. Twenty-one of the benign tumors and 8 of the malignant tumors were excised totally and the remainder subtotally. On follow-up ranging from 3 to 48 months, one subtotally excised meningioma recurred and was treated with re-excision and adjuvant radiation therapy. Two "totally" excised malignant tumors recurred outside the cavernous sinus at the margins of excision. There was no operative mortality or permanent cerebral morbidity. Postoperatively, the ocular and neurological function of most patients was similar to the preoperative status; in some, it was significantly improved. Thirteen additional patients with intracavernous neoplasms also were evaluated during the same period and followed without operation. The early follow-up information regarding these patients is provided.

Nasopharyngeal teratoma involving the temporal bone

Teratoma is the most common nasopharyngeal tumor in neonates. The tumor is usually limited to the oropharynx and is manifest by stridor and respiratory distress. Complete excision affects a cure. An unusual case of nasopharyngeal teratoma extending into the temporal bone, causing facial paralysis and conductive hearing loss, in addition to stridor, is presented. Stridor was relieved by transoral partial excision shortly after birth. Complete removal of the tumor by way of a subtemporal and infratemporal fossa approach was performed at 14 months of age. The defect was filled with a rectus abdominis muscle graft with microvascular anastomoses. The facial nerve was reconstructed secondarily with a sural nerve graft. The patient has no recurrence tumor and has good facial function at 30 months. This case demonstrates the first known case of facial paralysis due to nasopharyngeal teratoma. The surgical approach for tumor removal: lateral infratemporal fossa dissection, and the method of reconstruction: free rectus abdominis muscle flap with microvascular anastomoses, had so far not been described in a patient this young.

Comparison of MR imaging, CT, and angiography in the evaluation of the enlarged cavernous sinus

Twenty-one patients with enlargement of the cavernous sinus were studied with CT and MR imaging. Eighteen of the patients also had cerebral angiography. MR was superior to CT in differentiating parasellar aneurysms from neoplastic masses. MR was also superior to both CT and angiography in defining the relationships of cavernous sinus neoplasms to the internal carotid artery, pituitary gland, optic chiasm, infundibulum, and fifth cranial nerves. Only in the definition of bone erosion or hyperostosis was MR inferior to another method (CT). We conclude that MR should be the initial diagnostic study in patients with symptoms of a parasellar mass, with supplementation when necessary by CT and angiography.

Immediate microvascular reconstruction of combined palatal and midfacial defects

We describe a method for immediate one-stage reconstruction of combined palatal and midfacial defects using latissimus dorsi musculocutaneous free-tissue transfer. It has consistently provided healed wounds, restoration of palatal function, and preservation of facial contour while obviating the need for a palatal prosthesis. This reconstructive method, which uses only autogenous tissue, may offer a significant advantage in cases where more than a hemimaxillectomy is required, for compound defects resulting from the sacrifice of facial structures along with the maxillectomy, and in situations where the resection involves cranial base structures with a resultant need to separate the cranial contents from the oral and nasal cavities. Finally, it provides an alternative to prosthetic rehabilitation for the elderly patient with decreased or absent vision.

Elective resection of the internal carotid artery without reconstruction

Curability of skull base tumors is related to the ability to achieve a complete resection. Resection of the internal carotid artery with the tumor puts the patient at risk for catastrophic cerebral injury. Autogenous vein grafting is not always technically or physiologically possible. We present eight patients with tumors eroding the cranial base who underwent safe resection or occlusion of the internal carotid artery as predicted by three tests: 1. carotid arteriography, 2. temporary balloon occlusion of the internal carotid artery, and 3. xenon computerized tomography cerebral blood flow mapping. No patient suffered permanent central nervous system injury.

Recording and processing aneurysmal vibration signals in dogs

A specially designed computerized acoustic aneurysm detection system has been developed and used for recording the acoustic signal produced by aneurysms in dogs. Two transducer types, a modified horn-coupled microphone and a microvascular intra-operative Doppler flowmeter have been used. The results show that the aneurysm signal is time-varying and that a stronger vibration signal can be obtained if a proximal stenosis presents. With direct contact recording, the acoustic signals from aneurysms and parent arteries show different characteristics that can be easily distinguished. The aneurysm signals are processed by spectrograms, and a smoothing technique for suppressing noise is introduced.

Contributions from the auditory nerve to the brain-stem auditory evoked potentials (BAEPs): results of intracranial recording in man

Intraoperative recordings obtained from electrodes placed on the scalp (vertex and earlobe or ear canal) in response to click stimulation were compared with recordings made directly from the auditory nerve in patients undergoing microvascular decompression (MVD) operations to relieve hemifacial spasm (HFS) and disabling positional vertigo (DPV). The results support earlier findings that show that the auditory nerve is the generator of both peak I and peak II in man, and that it is the intracranial portion of the auditory nerve that generates peak II. The results indicate that the second negative peak in the potentials recorded from the earlobe is generated by the auditory nerve where it passes through the porus acusticus into the skull cavity, and that the proximal portion of the intracranial portion of the auditory nerve generates a positive peak in the potentials that are recorded from the vertex. This peak appears with a latency that is slightly longer than that of the second negative peak in the potentials recorded from the earlobe (or ear canal). The second negative peak in the recording from the ear canal and the positive peak in the vertex recording contribute to peak II in the differentially recorded BAEP. Since our results indicate that the difference in the latency of the second negative peak in the recording from the earlobe and that of the positive peak in the vertex recording represents the neural travel time in the intracranial portion of the auditory nerve, this measure may be valuable in the differential diagnosis of eighth nerve disorders such as vascular compression syndrome.

Value of transcranial Doppler examination in the diagnosis of cerebral vasospasm after subarachnoid hemorrhage

In 21 patients with subarachnoid hemorrhage secondary to ruptured intracranial aneurysms, we performed serial neurological evaluations, transcranial Doppler examinations, and cerebral blood flow (CBF) determinations. We classified 8 patients as having vasospasm (delayed neurological deterioration, appropriate reduction of CBF) and 13 patients as having no spasm on the basis of this information. Transcranial Doppler flow velocities in the middle cerebral artery and the anterior cerebral artery were significantly elevated for the group with vasospasm on posthemorrhage Days 4 through 12. Elevation of transcranial Doppler velocities preceded clinical signs of cerebral ischemia. The maximal transcranial Doppler flow velocities achieved were compared on the basis of the extent of clot on early computed tomographic (CT) scans. The mean anterior cerebral artery flow velocities were significantly different between CT Grades II and III. The initial transcranial Doppler flow velocities were compared on the basis of the patient's Hunt and Hess grade upon admission. The flow velocities for Grade V patients were significantly lower than those for Grade IV patients. Transcranial Doppler flow velocities were compared with arteriographically observed anterior cerebral artery and middle cerebral artery radii in 12 instances. The correlation was poor, but the data should be interpreted cautiously in view of the small number of arteriograms. We conclude that transcranial Doppler examination has considerable potential in the early diagnosis of delayed ischemic neurological deficit (clinical vasospasm) in patients with subarachnoid hemorrhage.

Intra-aneurysmal pressure measurements in experimental saccular aneurysms in dogs

Intra-aneurysmal pressure was studied in an experimental model of saccular aneurysm in dogs, using a vein pouch grafted onto a common carotid arterial bifurcation. The mean and the pulse pressures were recorded simultaneously from within the aneurysm and within the common carotid artery, before and after 50% proximal carotid artery stenosis. These experiments were performed under systemic normotension, hypotension, and hypertension. Normal data suggest that mean intracarotid and intra-aneurysmal pressures are similar and relate in a nearly linear fashion to mean arterial pressure. However, after 50% stenosis, the data had a cubic relationship, the reduction of pressure occurring only in the middle range of mean arterial pressure. Both intra-aneurysmal and intracarotid pulse pressures displayed less dependence on mean arterial pressure. However, sigmoid curves also were observed with the pulse pressures after 50% proximal common carotid artery stenosis. In all cases, after 50% stenosis, the rate of increase of the pulse pressures with mean arterial pressure was greater for higher mean arterial pressures. Our preliminary data indicate that a detailed study of intra-aneurysmal pressure and blood flow in relation to systemic variables such as mean arterial pressure, cardiac output, and peripheral resistance may not only suggest improved means of managing patients with intracranial aneurysms, but also may raise the possibility that, under certain conditions, higher intra-aneurysmal pressures may be induced by downstream stenosis.

Subtemporal-infratemporal and basal subfrontal approach to extensive cranial base tumours

A subtemporal-infratemporal and basal subfrontal approach for the removal of extensive, predominantly extradural cranial base neoplasms is described. This approach was used successfully in six of our patients. The advantages of this approach are extensive exposure of the anterior and mid-cranial base as well as the clivus, direct exposure and management of the ipsilateral petrous and cavernous internal carotid artery (ICA), and access to extracranial vessels for microvascular flap transfer. Disadvantages include prolonged operative time and less control of the contralateral petrous ICA. Six patients with extensive cranial base neoplasms had operations using this technique without any mortality or major permanent morbidity. The value of this approach to patients in terms of control or cure of extensive cranial base tumours has to be proven by long term follow-up.

Anatomical study of the cavernous sinus emphasizing operative approaches and related vascular and neural reconstruction

The efficacy of three operative approaches to the cavernous sinus (CS) and the possibilities of vascular and cranial nerve reconstruction in and around the CS were studied in 50 cadaver specimens (25 heads). The lateral operative approach was through the lateral wall, between Cranial Nerves V1 and IV, or between Cranial Nerves V1 and V2. The superior approach was through the superior wall of the CS after removing the anterior clinoid process and unroofing the optic canal. The inferior approach followed the petrous internal carotid artery (ICA) into the CS after an extradural subtemporal exposure or after a combined subtemporal and infratemporal fossa exposure. The different exposures of the spaces of the CS and of the intracavernous structures provided by the superior and the lateral approaches were complementary. The exposure provided by the inferior approach was minimal; however, the junction of the petrous and cavernous ICA was best exposed by this route. The combined subtemporal and infratemporal fossa approach exposed the petrous ICA (for proximal control or for reconstruction) with the greatest ease and with the least temporal lobe retraction. The combination of the superior and lateral approaches and the complete mobilization of the intracavernous ICA facilitated its repair after experimental lacerations. Lacerations of either the inferior and the inferomedial aspects of any portion of the cavernous ICA or of the anterior surface of the posterior vertical segment of the artery were the most difficult to repair. End-to-end anastomosis was more difficult with the posterior third of the artery than with the anterior two-thirds. A vein graft with an average length of 3.5 cm could be sutured from the petrous to the supraclinoid ICA to bypass the cavernous ICA, with an average occlusion time of 45 minutes. End-to-end technique was judged better for the proximal anastomosis, but end (graft)-to-side anastomosis was easier to perform at the distal end because of the location of the ophthalmic artery. Resuture of Cranial Nerves III and VI could not be performed in fresh cadavers if the gap exceeded 0.3 cm. In 3 specimens, the exposure of Cranial Nerve VI in the posterior fossa through the petrous apex and in the orbital apex was followed by graft placement (bypassing the CS). The complex anatomy of the cranial nerves at the apex of the CS was also defined in 10 specimens. Surgeons who perform operations in and around the CS for neoplastic and vascular lesions will find these studies useful.

Recording compound action potentials from the optic nerve in man and monkeys

Compound action potentials were recorded from the optic nerve in patients undergoing neurosurgical operations and in rhesus monkeys. The stimuli were short light flashes delivered by light-emitting diodes that were bonded to plastic contact lenses positioned on one or both eyes, and potentials were recorded simultaneously from electrodes placed on the scalp. Potentials recorded from the optic nerve in man have an initial small positive deflection, with a latency of about 45 msec, followed by a negativity with a latency of 60-70 msec. The wave form depends on the recording site on the optic nerve and, occasionally, oscillations with a frequency around 100 Hz were seen in the responses from the optic nerve. There was considerable individual variation in the shape and size of the recorded potentials, but most potentials recorded simultaneously from an electrode placed on Oz with a reference electrode on the forehead appeared as positive deflections with latencies of about 80 msec and, occasionally, with a small positivity with a latency of about 45 msec. Compound action potentials recorded from the optic nerve near the ocular globe in the rhesus monkey in response to similar light flashes appeared as negative deflections with latencies of about 17 msec. The potentials recorded at the chiasm appeared as initial positive deflections, with the latency of the earliest peak being about 35 msec, on which oscillations with frequencies of about 100-150 Hz occasionally could be seen. The recordings from electrodes placed on the scalp (Cz-Oz and Cz-shoulder) in the monkey showed a positive peak with a latency of about 65 msec.(ABSTRACT TRUNCATED AT 250 WORDS)

Subtemporal-preauricular infratemporal fossa approach to large lateral and posterior cranial base neoplasms

A subtemporal-preauricular infratemporal fossa approach to remove 22 large neoplasms involving the lateral and posterior cranial base is detailed. The areas from which a neoplasm could be removed by this approach included the sphenoid and clival bone; the medial half of the petrous temporal bone; the infratemporal fossa; the nasopharynx; the retro- and parapharyngeal area; the ethmoid, sphenoid, and maxillary sinuses; and the intradural clivus-foramen magnum area. The pathology of the neoplasms included benign tumors such as meningioma, malignant cartilaginous neoplasms such as chordoma, and other malignant lesions such as nasopharyngeal carcinoma. This approach offers many advantages over other anterior and lateral approaches to the lateral and posterior cranial base: these include minimal brain retraction; direct access to the ipsilateral petrous and upper cervical internal carotid artery; reconstruction of extensive cranial base defects, often with the use of a vascularized rectus abdominus flap; preservation of the hearing conduction mechanism when it is not involved by tumor; and the maintenance of excellent facial nerve function postoperatively. The use of an anterior extradural approach (transethmoidal) and of an intradural approach (frontotemporal or retromastoid), either concurrently or separately, is necessary in some patients to effect total tumor removal. The most serious complication in this series was the death of a patient due to postoperative infection and bilateral carotid artery rupture, which may have been avoided by the use of a rectus abdominis muscle flap for reconstruction. Among the 21 surviving patients, 18 had a good outcome, two had a fair outcome, and one with preexisting neurological deficits had a poor outcome. One of the surviving patients with a chordoma died of pulmonary metastases 1 year later, without evidence of local recurrence. The length of postoperative follow-up evaluation in these patients is insufficient to make any judgment about the effectiveness of this surgical approach in achieving a cure or long-term control of the tumors described.