Intermittent vertebral artery compression caused by C1-root schwannoma: case report

Extradural schwannomas of the C1-root are extremely rare. As the tumor grows in size, it may compress surrounding neurovascular structures and cause symptoms. In the present case report, the left vertebral artery (VA) was severely compressed by the tumor, eliciting severe vertigo on turning the head to the right side and with neck extension. We report a 52-year-old man who presented with a history of intermittent episodes of severe vertigo on head movement that was caused by a C1-root schwannoma. The lesion was exposed through an extreme lateral transcondylar approach. At exposure the lesion was yellowish in color and was extradural in location lying between the markedly eroded C1-posterior arch and the compressed vertebral artery (V3) on the left side. The medial portion of the tumor was attached to the C1-nerve root. The tumor was excised enbloc with decompression of the VA. The patient's symptoms completely resolved immediately following surgery, with no recurrence of the symptoms at one year follow up. The vertebral artery may frequently be compressed by osteophytes in cervical spondylosis or due to other causes in the cervical spinal canal, but compression of the artery by C1 extradural schwannoma with vascular insufficiency is rare. Removel of the tumor and the resultant decompression of the artery can be facilitated by the extreme lateral approach as demonstrated by this case.

Vertebral artery to common carotid artery bypass in Takayasu's disease with delayed cerebral ischemia

Takayasu's Arteritis is a progressive occlusive disease of the aortic arch and its branches. It may need several bypass procedures along with or without endovascular techniques.

CASE DESCRIPTIONS

A twenty-six year old woman who had a history of Takayasu's Arteritis, and had a Gore-Tex Dacron Y-graft from the ascending aorta to the right subclavian and right common carotid arteries 18 years before, is presented. She presented with recurrent hemispheric ischemia and transient ischemic attacks and severe long segment stenosis in the left common carotid artery. She was successfully treated with a saphenous vein graft bypass from the left vertebral artery to the common carotid artery. The stenosis of the brachiocephalic graft was successfully treated by angioplasty. Three months follow up showed stenosis of the left VA immediately proximal to the proximal anastomosis which was managed successfully with angioplasty.

CONCLUSIONS

The surgical treatment of Takayasu's Arteritis with bypass procedures needs a complex overview and follow up. A regular follow up is mandatory for evaluation and planning of appropriate management, in view of the progressive nature of the disease process.

Occipitocervical fusion following the extreme lateral transcondylar approach

BACKGROUND

Modern cranial base approaches to the clivus and foramen magnum may threaten the stability of the cranio-cervical junction. This necessitates stabilization and fusion in some cases. We studied occipitocervical fusion after extreme lateral transcondylar approaches.

METHODS

Twenty-seven patients underwent an extreme lateral transcondylar approach over a 2-year period. Two patients were excluded because of prior occipitocervical fusion. The pathological diagnosis was meningioma in ten patients, chordoma in six patients, neurofibroma in two, and 10 patients had other tumoral and nontumoral pathologies.

RESULTS

Eight patients required occipitocervical fusion and stabilization. Five of six patients with chordomas required fusion, whereas no patient with a meningioma underwent fusion. All the patients who were fused had more than 70% resection of their occipital condyle. No patient with resection of less than 70% of the occipital condyle required fusion. Significant interference of the surgical construct with follow-up imaging was seen only in the patient in whom a stainless steel Steinman pin was used.

CONCLUSION

One third of patients will require fusion after extreme lateral transcondylar approaches. Most patients with less than 70% resection of the condyle remain stable without need for surgical intervention, whereas complete resection necessitates fusion in most cases.

Use of intra-aortic balloon pump counterpulsation for refractory symptomatic vasospasm

Delayed neurologic deficits secondary to vasospasm remain a vexing problem. Current treatments include: hypertensive hypervolemic hemodilution (Triple-H) therapy, angioplasty, and intra-arterial papaverine administration. Significant morbidity and mortality still result from vasospasm despite these therapies. We present two patients with symptomatic vasospasm who received intra-aortic balloon pump counterpulsation (IABP) to improve cerebral blood flow when they were unable to tolerate Triple-H therapy. One patient (L.T.) developed vasospasm after resection of a meningioma that encased the carotid and middle cerebral artery. The other patient (D.F.) suffered a subarachnoid hemorrhage (Fisher Grade III, Hunt/Hess Grade III) from a basilar tip aneurysm. Postoperatively, both patients developed vasospasm. Treatment with Triple-H therapy, angioplasty, and papaverine yielded modest results. When they experienced cardiac ischemia, Triple-H therapy was stopped, but their neurologic condition deteriorated markedly. Because of this, IABP was started. Both patients had an immediate improvement in cardiac function. IABP was able to reverse some of the neurologic deficits, and was weaned off after several days of support. Both patients had a substantial improvement in function, and are now capable of caring for themselves. We conclude that IABP may play an important role for improving cerebral blood flow in patients with vasospasm. It may be particularly useful in those patients with limited cardiac reserve.

Early arytenoid adduction for vagal paralysis after skull base surgery

OBJECTIVES

To evaluate the efficacy of early arytenoid adduction in the management of vagal paralysis after skull base surgery.

STUDY DESIGN

Retrospective evaluation at a tertiary care skull base center.

METHODS

Aggressive surgical management of skull base lesions has become increasingly popular owing to advances in surgical technique and intraoperative monitoring. Temporary and permanent lower cranial neuropathies occur frequently, especially after the surgical management of lesions involving the vertebrobasilar system and the jugular foramen. An injury to the proximal vagus nerve is usually associated with dysphonia and swallowing dysfunction. An early arytenoid adduction has been employed in 26 patients with a vagal paralysis after skull base surgery. Most commonly, the neurosurgical patient underwent an arytenoid adduction under general anesthesia on postoperative day 2.

RESULTS

Videostroboscopy after arytenoid adduction demonstrated 76% of patients had complete glottic closure. Of those with inadequate glottic closure, all demonstrated a well-medialized posterior glottis with a persistent anterior glottal gap. These patients were easily treated with a secondary type I thyroplasty under local anesthesia with sedation resulting in complete glottic closure. Despite excellent voice outcomes, 66% of these patients had dysphagia requiring enteral feedings for nutritional support.

CONCLUSIONS

An early arytenoid adduction is an excellent medialization technique that can be performed safely in the early postoperative period under general anesthesia after skull base surgery.

The rubber dam interposition technique during intracranial aneurysm clipping under deep hypothermic circulatory arrest

OBJECTIVE

We describe a technique for isolating perforating arteries by use of a rubber sheet during the clipping of intracranial aneurysms under deep hypothermic circulatory arrest.

METHODS

After meticulous dissection of the perforating arteries from the aneurysm, a rubber sheet, cut from a surgical glove to the proper shape, is inserted between the aneurysm and the arteries to prevent arterial reattachment to the aneurysmal neck.

RESULTS

Even when perforators are invisible at the time of neck clipping because of a large aneurysmal body, the blade of the clip slides along the rubber sheet without injuring the vessels.

CONCLUSION

With this method, an aneurysm, especially a large or giant one, can be clipped easily and safely even when the patient is in deep hypothermic circulatory arrest.

Vasospasm after cranial base tumor resection: pathogenesis, diagnosis, and therapy

OBJECTIVE

Cerebral vasospasm is well known to occur after various cerebral neurosurgical events that cause subarachnoid hemorrhage. However, cerebral vasospasm can occur after cranial base tumor resection. We present a series of nine patients with angiographically evident vasospasm that was clinically symptomatic in eight of them.

METHODS

A total of 470 consecutive patients with cranial base tumors were operated in our institution between April 1993 and December 1996. Nine had evidence of cerebral vasospasm postoperatively (1.9% of the total population), of whom eight were asymptomatic. There were seven males and two females with an age range of 33 to 65 years (average 48.5 years). There were seven meningiomas, one chordoma, and one trigeminal schwannoma.

RESULTS

Vasospasm manifested clinically 1 to 30 days postoperatively in eight patients. Most patients were symptomatic within 7 days. In the ninth case, surgery was delayed when asymptomatic vasospasm was noted on an angiogram before second stage surgery. Symptoms included altered mental status in four patients, hemiparesis in three patients (one patient had both hemiparesis and altered mental status), and monoparesis in two patients. Factors that were found to correlate with a higher incidence of vasospasm were tumor size, total operative time, vessel encasement, vessel narrowing, and preoperative embolization. All eight patients with symptomatic vasospasm were treated with hypertensive, hypervolemic, hemodilutional (HHH) therapy. Five patients also underwent intraluminal angioplasty, in conjunction with papaverine in one case. One patient received intraarterial papaverine alone. Angiographic results were good in all patients. Significant clinical improvement was seen in six of the eight symptomatic cases.

CONCLUSION

Delayed neurological deterioration in a patient who has undergone cranial base tumor surgery not explained by an intracranial mass lesion should be promptly investigated with angiography. If vasospasm is diagnosed, it should be treated aggressively with hypertensive, hypervolemic, hemodilutional therapy and early angioplasty.

Proposed grading system to predict the extent of resection and outcomes for cranial base meningiomas

OBJECTIVE

This investigation was performed to construct a grading system for cranial base meningiomas that augments the current system of topographic labeling. This new system classifies cranial base meningiomas based on predicted surgical resection and patient outcomes.

METHODS

Two hundred thirty-two consecutive patients with cranial base meningiomas were surgically treated by the two senior authors between April 1993 and August 1997. Using standard statistical tests, a large number of preoperative, intraoperative, and follow-up findings were analyzed for correlation with the extent of resection. These included the presence of previous radiotherapy, Cranial Nerve III, V, and VI palsies, multiple fossa involvement, and vessel encasement.

RESULTS

Analysis revealed that each variable tested was independently and inversely correlated with total tumor resection (P < 0.002). We were able to construct a grading system based on these variables; when more variables are present, the grade is higher. With the grading system, lower-grade tumors were correlated with increased probabilities of total resection (r2 = 0.9947) and better patient outcomes, as measured by Karnofsky performance scale scores (r = 0.9291). We also found that, as a group, patients who underwent subtotal resection exhibited worse Karnofsky performance scale scores and had longer hospital stays.

CONCLUSION

The current system of classifying cranial base meningiomas provides no information regarding the tumor except location and no information concerning patient prognosis. We present a more useful system to categorize these tumors. Our scheme must be tested at other centers to corroborate our findings. This new grading system should serve to guide surgical treatment, inform patients, and improve communication among surgeons.

Surgical management of cavernous malformations of the brain stem

Different surgical approaches to the brain stem with results of excision of brain stem cavernous malformations are reported. Nine patients with brain stem cavernous malformations were operated with six different approaches. The patients were evaluated neurologically, and by magnetic resonance imaging (MRI) examination. All patients had at least one and often more episodes of haemorrhage. Seven patients underwent the total removal of the malformation, without recurrence. One patient with a large medullary cavernoma had recurrence, but without further growth. One patient with a large pontomesencephalic malformation and partial resection, suffered rebleeding due to residual cavernoma. The mean follow-up period was 49 months (range 3-112). The results of surgery were excellent or good in eight patients, and poor (worsening) in one. It is concluded that surgical resection is recommended for the cavernous malformations of the brain stem which are symptomatic, have bled or are growing, and are approachable through one of the pial surfaces of the brain stem. Different skull base approaches are useful for this procedure. Radiosurgery is not recommended in such cases.

Subtonsillar-transcerebellomedullary approach to lesions involving the fourth ventricle, the cerebellomedullary fissure and the lateral brainstem

We describe the use of the subtonsillar-transcerebellomedullary approach to laterally placed fourth ventricle and brain-stem lesions. The subtonsillar-transcerebellomedullary approach to the fourth ventricle and the lateral brainstem was used in six patients: three patients with tumours of the fourth ventricle and brainstem (two ependymomas and one papillary thyroid carcinoma metastasis), two patients with cavernous angiomas of the brainstem and one patient with a distal posterior inferior cerebellar artery (PICA) aneurysm. The microsurgical anatomy of this approach was studied in five cadaveric head specimens. The tumours and cavernous angiomas were removed and the distal PICA aneurysm was clipped successfully. In all patients the Karnofsky performance scale (KPS) was equal to or better than the preoperative status on follow-up examinations. The anatomical studies also revealed the extensive exposure provided with this approach. The subtonsillar-transcerebellomedullary approach is recommended for lesions occupying the cerebellomedullary fissure, and the lateral aspect of the fourth ventricle.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Variations of the extreme-lateral craniocervical approach: anatomical study and clinical analysis of 69 patients

OBJECT

The aim of this study was to describe six variations of the extreme-lateral craniocervical approach, their application, and treatment results.

METHODS

During a 4-year period 69 patients underwent surgery in which six variations of the extreme-lateral craniocervical approach were performed. The variations included: the transfacetal approach (TFA), performed to treat four lesions in the upper cervical spine anterior or anterolateral to the spinal cord; the retrocondylar approach, to treat five intradural lesions located anterolateral to the medulla oblongata and six vascular lesions to expose the extradural segment of the vertebral artery (VA); the partial transcondylar approach (PTCA), to treat 18 intradural lesions located anterior to the medulla oblongata; the complete transcondylar approach (CTCA), to treat 13 extradural lesions that involved the lower clivus and anterior upper cervical spine; the extreme-lateral transjugular approach, to treat 14 jugular foramen tumors; and the transtubercular approach with or without division of the sigmoid sinus, to treat complex VA and vertebrobasilar junction aneurysms. An anatomical prosection was performed to study the surgical exposure of each of the six variations of the extreme-lateral craniocervical approach. Total removal was achieved in 35 (69%) of the patients with tumor; subtotal resection was achieved in 16 (31%) of those patients. In the 12 patients with VA aneurysms, seven underwent clipping, three underwent trapping and a vein graft bypass procedure, and two underwent trapping without the use of a bypass procedure. In five other patients, different cystic, inflammatory, and other vascular lesions were successfully treated. Fifty percent of the patients who underwent surgery via the TFA, 83% via the of the CTCA, and 11% via the PTCA required an occipitocervical fusion procedure. The mean Karnofsky Performance Scale score was 74.7 preoperatively and 76.4 postoperatively. Major complications were hydrocephalus (nine patients), cerebrospinal fluid leakage (seven patients), worsened cranial nerve function (seven patients), vertebrobasilar vasospasm (one patient), and sigmoid sinus thrombosis (one patient).

CONCLUSIONS

To treat lesions in the region of the foramen magnum and surrounding areas, the approach should be tailored to each specific lesion to provide the needed exposure without unnecessary operative steps.

Profound hypothermia and circulatory arrest with skull base approaches for treatment of complex posterior circulation aneurysms

OBJECTIVE

Cardiopulmonary bypass with profound hypothermia and circulatory arrest has seen a resurgence as an adjunct technique in neurological surgery. We report our experience with this technique in treating seven complex vertebro-basilar aneurysms.

METHODS

Skull base approaches were used in all cases, providing excellent exposure and minimizing brain retraction. There were six basilar artery aneurysms and one giant fusiform vertebro-basilar artery aneurysm. All aneurysms but one had an apparent neck, which could be clipped. The fusiform vertebro-basilar artery aneurysm was trapped, partially resected, and the circulation was reestablished with a saphenous vein graft from the cervical internal carotid artery to the mid-basilar artery.

RESULTS

Five patients had an excellent outcome and two had a good outcome at one year or at latest follow up. Two of the patients showed improvement of neurological deficits which were present before the surgical intervention.

CONCLUSION

Applying very strict selection criteria in this small series of patients with posterior circulation aneurysms, excellent or good results were achieved using the profound hypothermic circulatory arrest technique.

Partial labyrinthectomy petrous apicectomy approach to neoplastic and vascular lesions of the petroclival area

OBJECTIVE

To study the value of an improvement of the presigmoid petrosal approach to the petroclival area by the addition of partial labyrinthectomy and petrous apicectomy and to document hearing and other results.

METHODS

Thirty-six consecutive patients treated by this technique during a 2-year period were studied prospectively. The lesions treated included 33 petroclival neoplasms (25 meningiomas, 5 chordomas, 1 chondrosarcoma, 1 trigeminal schwannoma, and 1 epidermoid cyst) and 3 vertebrobasilar aneurysms. The patients underwent clinical, radiological, and neuro-otological examinations.

RESULTS

There was no perioperative mortality. Cranial nerve deficits involving Cranial Nerves III, IV, V, and VI occurred in 17 patients (47%) postoperatively. Cerebrospinal fluid leak occurred in 12 patients (33%). Four of these patients were treated by lumbar drainage, two patients were treated by lumboperitoneal shunt, and six patients required reoperation and repacking of the middle ear. Hydrocephalus occurred in five patients (13.9%). There was one case of meningitis and another of systemic sepsis. All 36 patients underwent postoperative audiometric evaluation. When serviceable hearing was present preoperatively (Gardner-Robertson Grades I or II), it was determined to be preserved at postoperative follow-up in 81% of the patients (26 of 32 patients).

CONCLUSION

The partial labyrinthectomy petrous apicectomy approach provided improved access to neoplasms of the clivus and petrous apex and the posterior cavernous sinus area and to vertebrobasilar aneurysms in the midclival area. This improvement in access permits more controlled and thorough treatment of these lesions, with reduced brain retraction and acceptable morbidity with respect to auditory function.

Reconstruction of the vein of Labbé by using a short saphenous vein bypass graft. Technical note

Protection of the vein of Labbé is a significant concern during surgery that involves retraction of the temporal lobe. A cranial base surgical approach, especially one via the presigmoid-petrosal route, carries considerable risk to this venous complex. A case is presented in which a large dominant vein of Labbé was injured during resection of a petroclival meningioma. This vein drained all the sylvian venous circulation as well as the lateral temporal surface; no connection to another venous system was noted. The vein was successfully reconstructed using a short saphenous vein bypass graft. Significant complications could have occurred without this reconstruction. The technique and benefits of this type of reconstruction are discussed.

Surgical anatomy of the infratemporal fossa: the styloid diaphragm revisited

INTRODUCTION

The infratemporal fossa (ITF) gives passage to most major cerebral vessels and cranial nerves. Dissection of the ITF is essential in many of the lateral cranial base approaches and in exposure of the high cervical internal carotid artery (ICA). We reviewed the surgical anatomy of this region.

METHODS

Direct foraminal measurements were made in seven dry skulls (14 sides), and the relationship of these foramina to each other and various landmarks were determined. Ten ITF dissections were performed using a preauricular subtemporal-infratemporal approach. Preliminary dissections of the extracranial great vessels and structures larger than 1 cm were performed using standard macroscopic surgical techniques. Dissection of all structures less than 1 cm was conducted using microsurgical techniques and instruments, including the operating microscope. The anatomic relationships of the muscles, nerves, arteries, and veins were carefully recorded, with special emphasis regarding the relationship of these structures to the styloid diaphragm. The dissection was purely extradural.

RESULTS

The styloid diaphragm was identified in all specimens. It divides the ITF into the prestyloid region and the retrostyloid region. The prestyloid region contains the parotid gland and associated structures, including the facial nerve and external carotid artery. The retrostyloid region contains major vascular structures (ICA, internal jugular vein) and the initial exocranial portion of the lower Cranial Nerves IX through XII. Landmarks were identified for the different cranial nerves. The bifurcation of the main trunk of the facial nerve was an average of 21 mm medial to the cartilaginous pointer and an average of 31 mm medial to the tragus of the ear. The glossopharyngeal nerve was found posterior and lateral to stylopharyngeus muscle in nine cases and medial in only one. The vagus nerve was consistently found in the angle formed posteriorly by the ICA and the internal jugular vein. The spinal accessory nerve crossed anterior to the internal jugular vein in five cases and posterior in another five cases. It could be located as it entered the medial surface of the sternocleidomastoid muscle 28 mm (mean) below the mastoid tip. The hypoglossal nerve was most consistently identified as it crossed under the sternocleidomastoid branch of the occipital artery 25 mm posterior to the angle of the mandible and 52 mm anterior and inferior to the mastoid tip.

CONCLUSION

The styloid diaphragm divides the ITF into prestyloid and retrostyloid regions and covers the high cervical ICA. Using landmarks for the exocranial portion of the lower cranial nerves is useful it identifying them and avoiding injury during approaches to the high cervical ICA, the upper cervical spine, and the ITF.

Persistent trigeminal artery: an anatomic study

INTRODUCTION

The most frequent embryonic communication between the vertebrobasilar and carotid systems is a persistent trigeminal artery (PTA). It has been observed in 0.1 to 0.2% of cerebral angiograms. We found this variation in an anatomic specimen, and after microscopic dissection, we performed an analysis of the course of the PTA and its relationship with the abducens nerve and the meningohypophyseal trunk.

METHOD

A PTA was incidentally encountered in an injected cadaver specimen during a transpetrosal approach. This embryonic variation and its anatomic relationship are discussed.

RESULTS

The PTA can take either a lateral or medial course regarding its relationship with the abducens nerve. When the PTA originates from the posterolateral aspect of the posterior bend of the cavernous carotid artery (C4 segment), it crosses underneath and distorts the abducens nerve, continuing between the abducens and trigeminal nerves. When taking a medial course, the PTA arises from the posteromedial aspect of the posterior bend of the cavernous carotid at the same segment and pierces the clival dura at the dorsum sellae. Cranial nerve displacement or distortion is less likely in this variation. In an analysis of carefully described anatomic studies, the PTA and meningohypophyseal trunk were found arising from either common or separated origins.

CONCLUSION

The most frequent embryological anastomosis between the carotid and vertebrobasilar system is the PTA. Its course and relationship with the cranial nerves may determine its clinical presentation.

The predictive value of intraoperative somatosensory evoked potential monitoring: review of 244 procedures

INTRODUCTION

There is some controversy regarding the value of intraoperative neurophysiological monitoring in predicting postoperative neurological deficits. We discuss our experience with the use of intraoperative somatosensory evoked potentials (SSEPs) during surgery of cranial base tumors.

METHODS

We retrospectively reviewed all of the procedures that had been performed for the resection of cranial base tumors from July 29, 1993, through March 16, 1995. One hundred ninety-three consecutive patients had undergone a total of 244 procedures. SSEP waveforms were classified as follows: Type I, no change; Type II, change that reverts to baseline; Type III, change that does not revert to baseline; and Type IV, complete flattening of the SSEP waveform without improvement. Two patients had no waveforms from the beginning of the case (Type V) and were excluded from further analysis. New immediate postoperative neurological deficits were recorded.

RESULTS

There were 64 male and 129 female patients, with a mean age of 46.6 years. One hundred seventy-seven patients had Type I SSEP waveforms, 13 of whom had postoperative deficits (7%). Fifty-six patients had Type II SSEPs, and nine (16%) of them had postoperative neurological deficits. Six patients had Type III SSEPs, and three had Type IV SSEPs, all of whom (100%) had postoperative deficits. There was a correlation between SSEP type and the results of the postoperative neurological examinations. The positive predictive value is 100%, and the negative predictive value is 90%. Although a change in the waveform that did not revert to baseline (Types III and IV) always predicted a postoperative deficit, a normal waveform did not always rule out postoperative deficits. Pathological abnormality, vessel encasement, vessel narrowing, degree of cavernous sinus involvement, brain stem edema, middle fossa location, final amount of resection, age, and tumor size correlated with a high predictive value of SSEP monitoring on univariate analysis (P < 0.05). None of these variables correlated significantly on multivariate analysis (P > 0.05), although brain stem edema was close (P = 0.0571).

CONCLUSION

Intraoperative SSEPs have a high positive predictive value during surgery for cranial base tumors, but they do not detect all postoperative deficits.

Anatomy of the frontotemporal branch of the facial nerve and indications for interfascial dissection

INTRODUCTION

Many studies have been conducted of the surgical anatomy of the frontotemporal branch of the facial nerve (FTBFN). However, very few have addressed the indications for interfascial dissection. When the zygomatic arch needs to be exposed, the interfascial approach is recommended to protect the FTBFN. With the transbasal or subfrontal approaches, however, when a bicoronal skin incision is used, the need for the interfascial approach is not clear.

METHODS

We studied 10 temporal regions (5 cadaveric heads). We dissected the recognized fascial layers of the temporal region and the FTBFN. We performed a histological study in a sixth specimen.

RESULTS

We observed the following. 1) The galea and the superficial layer of the deep temporal fascia become fused in a curved line from the lateral orbital border 2.8 cm above the zygomatic arch to a point 3 cm posterior to the inferolateral angle of the orbit. 2) After this transitional area of adherence, the subgaleal loose cellular layer is lost and is replaced by a fibrofatty tissue. 3) The FTBFN in its course above the zygomatic arch runs in this tissue layer without being protected by the galea. 4) Over the superolateral angle of the orbital rim, the galea protects FTBFN, and there are no subgaleal adhesions in that area.

CONCLUSION

Ahove the zygomatic arch, the FTBFN is not protected by the galea. During bicoronal approaches, if only the superolateral angle of the orbital rim needs to be exposed and not the zygomatic arch, there is no need to protect the FTBFN using an interfascial approach.

An increase in extracellular glutamate is a sensitive method of detecting ischaemic neuronal damage during cranial base and cerebrovascular surgery. An in vivo microdialysis study

All patients undergoing neurological surgery are at risk for serious complications. Ischaemic damage presenting with hemiparesis or speech difficulties occurs in up to 6% of patients undergoing cerebral bypass procedures and other complicated neurosurgical procedures. Currently available methods for detection of such damage include the use of somatosensory evoked potentials (SSEPs) and electro-encephalography (EEG). Unfortunately, these techniques have false positives and may remain normal in the presence of severe focal neurological deficits. Early detection of potential deficits may prevent or minimize damage through a change in operative or anaesthetic strategy. With the availability of several potential neuroprotective compounds, it is also possible to treat patients at risk of developing ischaemic complications if the individuals are identified early. The excitatory neurotransmitter glutamate is not only a metabolic product, but is also thought to promote ischaemia induced cell injury if released into the extracellular space. It may be a significant parameter for ischaemic brain metabolism. In this report we describe 10 patients who underwent extracranial-intracranial (EC-IC) high flow bypass procedures with routine intra-operative monitoring (IOM) as well as intra-operative in-vivo microdialysis measurement of glutamate. Our aim was to compare intra-operative microdialytic findings and IOM findings with respect to patients' early postoperative clinical courses. Three patients had significant intra-operative glutamate increases indicating ischaemia. Two of these patients awoke with a new neurological deficit (hemiparesis). Routine IOM findings were either normal or showed only transient changes during the time the glutamate levels were high. Our study shows that an increase in extracellular glutamate, as monitored by in-vivo microdialysis, is an excellent early market of neuronal damage. While our glutamate measurements were done off-line, it may be possible to get in future continuous on-line measurements to serve as an early warning system for potential ischaemic damage.

Endodermal cysts of the posterior fossa. Report of three cases and review of the literature

The pathogenesis of endodermal cysts of the posterior fossa is still incompletely understood. The authors reviewed three new cases and those reported in the literature to clarify the clinical, pathological, radiological, and surgical characteristics of these lesions. A total of 49 cases were reviewed. Details on demographic profiles, clinical characteristics, histopathological and radiological features, and surgical methods were collected. These cysts have a predominance in male patients (61%) and can occur at any age (birth-77 years). In patients with posterior fossa endodermal cysts there is a bimodal age distribution and headache is the most frequent complaint. On immunohistopathological examination, endodermal cysts were reactive for epithelial membrane antigen and for keratin immunostains whenever the latter were tested. The cysts were reactive for carcinoembryonic antigen in nine of 11 cases. Endodermal cysts were located anterior to the brainstem in 51% of cases and in the fourth ventricle in 21% of cases. They frequently appeared hypodense on computerized tomography scans, and in five cases, the lesion was missed. The cyst's appearance on magnetic resonance imaging is variable. Resection was complete in 19 cases and partial in 11; marsupialization was achieved in two cases. Three recurrences have been reported. Total excision with preservation of neurological function should be the goal. Cranial base approaches are helpful for surgical access in selected examples of these lesions.

The petrolingual ligament: the anatomy and surgical exposure of the posterolateral landmark of the cavernous sinus

The petrolingual ligament is the posteroinferior attachment of the lateral wall of the cavernous sinus, where the internal carotid artery enters the cavernous sinus. The petrous segment of the internal carotid artery finishes and the cavernous segment begins at the superior margin of this ligament. The ligament is surgically important due to its identification as a landmark for dissection of the internal carotid artery during the approaches to posterolateral intracavernous and extracavernous lesions. It can be well exposed after mobilization of the gasserian ganglion, or after the trigeminal root and ganglion have been split along the junction of V2 and V3 (the transtrigeminal approach). The petrolingual ligament was studied in five cadaveric head specimens from ten sides. The size of the ligament was measured, and its anatomical, clinical and surgical importance is discussed.

Extradural origin of the posteroinferior cerebellar artery: an anatomic study with histological and radiographic correlation

OBJECTIVE

The posteroinferior cerebellar artery (PICA) usually arises from the intradural segment of the vertebral artery (VA). The extradural origin of the PICA is infrequent. Its preoperatory identification is important in surgical strategy during the exposure of the VA.

METHODS

During an anatomic prosection, the VA was exposed at the craniocervical junction in cadaveric adult specimens. The extradural origin of the PICA was encountered bilaterally in one specimen and on one side in a second specimen. An anatomic study with histological and radiographic correlation was performed.

RESULTS

Perforating branches originate from the PICA. They supply the middle and inferior third of the olive and the lateral aspect of the medulla. The PICA has cortical branches that lead to the cerebellum. Injury to the PICA can produce an infarction of these neural structures that can be asymptomatic or cause major neurological deficits. Radiographic results obtained using a lateral projection provided the most reliable delineation of the extradural origin of the PICA. When this artery originates at, or posterior to, the posterior aspect of the occipital condyle, an extradural origin is likely.

CONCLUSION

Bilateral selective vertebral angiography should be performed with special attention to the relationships of PICA origins before any surgical exposure of the VA at the craniocervical junction, unless magnetic resonance angiography provides this information without question. A thorough understanding of the relative dominance of the VAs and PICAs, the location of the PICA origin, and the collateral circulation of the posterior fossa are prerequisites to surgery in this region. The preoperative identification of an extradural PICA is important in planning surgical strategy and in avoiding complications during operations near the foramen magnum.

Combined supra/infratentorial-transsinus approach to large pineal region tumors

OBJECT

The authors sought to confirm that the combined supra/infratentorial-transsinus approach offers a safer means of resecting large pineal region tumors than other approaches currently being used. The aforementioned method provides a wider exposure of the pineal region with less brain retraction than the infratentorial-supracerebellar or the occipital-transtentorial approach alone and is applicable to some large and giant tumors of this area. This combined approach was used in six patients to remove large pineal region tumors including four tentorial meningiomas, one pineocytoma, and one epidermoid cyst.

METHODS

The transverse sinus and tentorium were sectioned after review of preoperative angiographic studies, after taking intraoperative measurements of the venous pressure in the nondominant transverse sinus before and after clipping and while monitoring the somatosensory evoked potentials. The occipital lobe cortex and cerebellum were retracted slightly along the tentorium. Deep veins of the galenic system, the quadrigeminal area, and the tumor were well exposed. Before it was used for tumor resection the approach was studied in five cadaveric head specimens, and the projection of different approaches was compared radiologically. The tumors were removed in a gross-total manner in all patients, and none of the major veins of the galenic system was injured. Resuturing of the nondominant transverse sinus was performed postoperatively in one patient. One of the six patients experienced transient visual loss, and another suffered mild right sixth cranial nerve paresis; however, both recovered in 3 weeks. The wide exposure of the combined approach was also confirmed on radiological and anatomical studies.

CONCLUSIONS

The combined supra/infratentorial-transsinus approach is preferred for the resection of certain large pineal region tumors.

The efficacy and safety of angioplasty for cerebral vasospasm after subarachnoid hemorrhage

OBJECTIVE

Cerebral angioplasty is being increasingly used for symptomatic vasospasm secondary to subarachnoid hemorrhage. We attempted to determine the safety and efficacy of angioplasty for refractory vasospasm. We also looked at the influence of timing of angioplasty on outcome.

METHODS

We retrospectively studied patients with subarachnoid hemorrhage who underwent angioplasty in our institution to determine the safety and the success rate achieved with this procedure. The study period extended from August 1993 until February 1997. Clinical and radiological data were collected, with emphasis on clinical improvement after angioplasty and its relationship with timing of intervention. Thirty-one patients with 43 aneurysms and one case of arteriovenous malformations were included. Their ages varied between 28 and 68 years, with an average age of 44 years. Five patients were assigned Hunt and Hess Grade IV, 15 were assigned Grade III, 7 were assigned Grade II, and 4 were assigned Grade I. All patients except two underwent angioplasty after aneurysm clipping or coiling.

RESULTS

Angioplasty was performed an average of 6.9 days after the occurrence of subarachnoid hemorrhage, with a range from 1 to 14 days. It was performed early (within 24 h) after refractory clinical deterioration in 21 patients. A total of 81 vessels were dilated. Three angioplasty-related complications occurred: two femoral hematomas and one retroperitoneal hematoma. Clinical improvement was dramatic after 12 procedures, moderate after 11 procedures, and minimal or nonexistent after 9 procedures. There was a clear tendency toward more significant improvement in patients with earlier angioplasty (<24 h from onset of neurological deficit) (P=0.0038). At discharge, 8 patients had achieved good recoveries (Glasgow Outcome Scale score of 1), 11 had moderate disabilities (Glasgow Outcome Scale score of 2), and 10 had severe disabilities (Glasgow Outcome Scale score of 3). Two deaths were encountered, and they were unrelated to angioplasty. Follow-up was obtained for 27 patients: 25 had good outcomes, 1 was moderately disabled, and 1 died. There was no significant correlation between interval and outcome.

CONCLUSION

Our results indicate that angioplasty is a safe and effective treatment for symptomatic vasospasm that is refractory to hyperdynamic hypervolemic therapy. When used early (<24 h), it leads to significant clinical improvement. However, the long-term outcome is good, even in cases of delayed angioplasty. The prevention of worsening of the cerebral ischemia and its extension to other territories may be the reason.

Cortical brain microdialysis and temperature monitoring during hypothermic circulatory arrest in humans

OBJECTIVES

Critical vascular surgery of the brain or the heart occasionally requires total cessation of the circulatory system. Profound hypothermia is used to protect the brain from ischaemic injury. This study explores the use of microdialysis to measure metabolic indices of ischaemia: glutamate, lactate, and pH, and cerebral temperature during profound hypothermia and circulatory arrest.

METHODS

Effluent from a microdialysis catheter placed in the cerebral cortex of three patients undergoing complete circulatory arrest was continuously sampled. Samples were pooled over 10 minute periods and glutamate and lactate concentrations were measured postoperatively. Brain temperature and pH were measured on line intraoperatively. Electroencephalography and monitoring of somatosensory evoked potentials and brainstem auditory evoked potentials were simultaneously carried out.

RESULTS

Patient 1 had normal glutamate and lactate. PH was 6.75 to 6.85 and increased to 6.9 after warming ensued. Patient 2 had raised glutamate and lactate during most measurements. The glutamate concentrations peaked at 305 microM/l at the start of the measurements and fell below 20 microM/l after warming. The lactate concentrations peaked at 680 microM/l before cooling, rose to 1040 microM/l during the cooling process, decreased to 212 microM/l during circulatory arrest, and rose again to 620 microM/l after warming. The pH started at 7.06 and continued a downward course until stabilising at a pH of 6.5 after circulatory arrest. Patient 3 had a transient, mild increase in glutamate and lactate during the cooling and warming period. pH was stable throughout.

CONCLUSION

Microdialysis combined with temperature and pH measurements of the cerebral cortex promises to be an important tool in detecting cerebral ischaemia. Further studies are needed to validate our findings and test the feasibility of modifying ischaemic changes.

Combined supra/infratentorial-transsinus approach to large pineal region tumors

Object

The authors sought to confirm that the combined supra/infratentorial-transsinus approach offers a safer means of resecting large pineal region tumors than other approaches currently being used. The aforementioned method provides a wider exposure of the pineal region with less brain retraction than the infratentorial-supracerebellar or the occipital-transtentorial approach alone and is applicable to some large and giant tumors of this area. This combined approach was used in six patients to remove large pineal region tumors including four tentorial meningiomas, one pineocytoma, and one epidermoid cyst.

Methods

The transverse sinus and tentorium were sectioned after review of preoperative angiographic studies, after taking intraoperative measurements of the venous pressure in the nondominant transverse sinus before and after clipping and while monitoring the somatosensory evoked potentials. The occipital lobe cortex and cerebellum were retracted slightly along the tentorium. Deep veins of the galenic system, the quadrigeminal area, and the tumor were well exposed. Before it was used for tumor resection the approach was studied in five cadaveric head specimens, and the projection of different approaches was compared radiologically.

The tumors were removed in a gross-total manner in all patients, and none of the major veins of the galenic system was injured. Resuturing of the nondominant transverse sinus was performed postoperatively in one patient. One of the six patients experienced transient visual loss, and another suffered mild right sixth cranial nerve paresis; however, both recovered in 3 weeks. The wide exposure of the combined approach was also confirmed on radiological and anatomical studies.

Conclusions

The combined supra/infratentorial-transsinus approach is preferred for the resection of certain large pineal region tumors.

Saphenous vein graft reconstruction of an unclippable giant basilar artery aneurysm performed with the patient under deep hypothermic circulatory arrest: technical case report

OBJECTIVE AND IMPORTANCE

Effective treatment for unclippable giant vertebrobasilar aneurysms remains unclear. We present the first reported case of a giant vertebrobasilar aneurysm being successfully treated with trapping of the aneurysm and internal carotid artery to basilar artery bypass with a saphenous vein graft that was performed with the patient under hypothermic circulatory arrest.

CLINICAL PRESENTATION

A 15-year-old female patient with a history of probable subarachnoid hemorrhage and chronic headaches presented with a relatively acute exacerbation of her headache, nausea, vomiting, and weakness. Imaging studies revealed a 4 x 4 x 3-cm vertebrobasilar aneurysm, supplied by an angiographically dominant right vertebral artery and causing significant brain stem compression.

INTERVENTION

Initially, a petrosal approach with a hearing-preserving partial labyrinthectomy was used to perform a right external carotid artery to posterior cerebral artery bypass with saphenous vein. Delayed occlusion of the right vertebral artery with an intraluminal balloon was planned; however, intraoperative angiography revealed poor graft flow, presumably because of the small size of the posterior cerebral artery. Postoperative graft occlusion was anticipated. During this same time interval, the patient deteriorated neurologically. Brain imaging failed to reveal evidence of cerebral infarction. The patient underwent subsequent surgery. After a total petrosectomy, the aneurysm was trapped, an aneurysmectomy was performed, and, with the patient under deep hypothermic circulatory arrest, a new interposition saphenous vein graft was inserted between the internal carotid and basilar arteries. Excellent flow was observed angiographically. At her 4-month follow-up examination, the patient had improved to near baseline.

CONCLUSION

We present a technically challenging but safe and definitive treatment option for an unclippable giant vertebrobasilar aneurysm. Using cranial base approaches and hypothermic circulatory arrest techniques, aneurysmal trapping and successful bypass grafting directly into the basilar artery was performed.

Intraoperative on-line monitoring of cerebral pH by microdialysis in neurosurgical procedures

The objective of this study was to improve the ability to detect cerebrovascular complications in patients undergoing complicated neurosurgical procedures using on-line monitoring of cerebral pH with in vivo microdialysis. We employed on-line pH monitoring in patients with a variety of neurosurgical procedures including high-flow bypass surgery, aneurysm clipping, and temporal resection in epilepsy treatment. The pH was monitored with a microdialysis probe, usually inserted into the frontal cortex and pH of the dialysate was measured on-line with a pH electrode. We monitored 17 cases: 12 high-flow extracranial-intracranial (EC-IC) bypass procedures, 3 surgeries to clip large basilar tip aneurysms under protection of hypothermic circulatory arrest, and 2 surgeries for intractable seizure disorders. In the patients undergoing high-flow bypass, the pH remained stable in 5 patients and all had an uneventful outcome. In 3 patients, the pH decreased during surgery. One patient had a severe hemiparesis on awaking from anesthesia. The fall in pH in another patient was corrected when the blood pressure was raised during surgery. The pH was also responsive to changes in intraoperative ventilation and probably also to brain edema with elevation of pH values. In the three patients undergoing basilar tip aneurysm clipping under hypothermic circulatory arrest, the pH fell to 6.41 in one patient. This patient awoke with a mild hemiparesis. In the other two patients, the pH was stable during the hypothermia and neither patient had complications. In the patients undergoing temporal lobectomy and hippocampectomy, the pH fell rapidly with the onset of ischemia. We conclude that it is possible to monitor the cerebral extracellular pH with on-line microdialysis. The information obtained may alert the surgeon to the possibility of impending cerebral ischemia or other complications. However, further experience is needed before the technique can be recommended for general use.

Current Concepts in the Management of Tumors of the Skull Base

BACKGROUND: Due to their involvement with critical neurovascular structures, tumors located in the cranial base present challenges to neurosurgeons and are associated with high morbidity and mortality. METHODS: Rates of tumor control, complications, patient outcomes, and recurrences were extracted and summarized from two decades of our surgical and radiological treatment follow-up and review of the medical literature. RESULTS: Recent advances in surgical techniques involving cranial base approaches have made surgical intervention safer and curative resection more likely. In managing benign tumors, surgical resection is the gold standard for treatment. While immediate complications are still significant, long-term outcomes in most cases are excellent. Focused radiosurgery using a gamma knife or linear accelerator has produced favorable outcomes, and it improves the management of small or minimally symptomatic cranial base tumors. For slow-growing malignant tumors, extensive surgery followed by radiotherapy achieves the best outcome. In managing highly malignant tumors, outcome is determined by the effects of chemotherapy and radiotherapy. On some occasions, surgery is needed to obtain greater control of highly malignant tumors. CONCLUSIONS: Skull base tumors are relatively common, and management of these tumors is rapidly evolving. The combination of surgical excision using cranial base techniques, radiosurgery, fractionated radiotherapy, and chemotherapy should be individually tailored based on the location and pathological aggressiveness of the tumor and the symptomatology of the patient.

Acoustic neuromas: results of current surgical management

OBJECTIVE

In this article, we review the surgical outcomes of 179 patients with acoustic neuromas.

METHODS

Most of the tumors (84%) were operated on using a retrosigmoid, transmeatal approach. A transpetrosal, retrosigmoid approach was used in 10% of the patients, most of whom had large tumors. The translabyrinthine (4%) and transmastoid, transpetrosal, partial labyrinthectomy approaches (2%) were used selectively. The operative approaches are discussed. Tumors were categorized according to their cerebellopontine angle dimensions as small (< 2 cm), medium (2.0-3.9 cm), and large (> or = 4 cm).

RESULTS

House-Brackmann evaluation of postoperative facial nerve function revealed excellent results (Grade I or II) in 96% of small tumors, 74% of medium tumors, and 38% of large tumors. A fair postoperative function (Grade III or IV) was achieved in 4% of small tumors, 26% of medium tumors, and 58% of large tumors. Functional hearing preservation, defined as Gardner-Robertson Class I or II, was achieved in 48% of small tumors and 25% of medium tumors. Hearing was not preserved in any of the three patients with large tumors in whom hearing preservation was attempted. Treatment complications consisted mainly of cerebrospinal fluid leakage (15% of the patients). The majority of the patients who experienced cerebrospinal fluid leakage were treated successfully with lumbar spinal drainage; only four patients (2% of the total group) required subsequent surgery for correction of cerebrospinal fluid leakage. There were two deaths (1%) in this series. One death occurred as the result of myocardial infarction and the other as the result of severe obstructive lung disease. One patient sustained disability because of cerebellar and brain stem injury. Complete tumor resection was accomplished in 99% of the patients, and there was no evidence of recurrence in this group. Only 1 of the 179 patients underwent incomplete tumor resection; he required subsequent surgery for symptomatic tumor regrowth. Our patient follow-up had a mean duration of 70 months and a median of 65 months (range, 3-171 mo).

CONCLUSION

Our results are similar to those of other large microsurgical series of acoustic neuromas. Unless a patient has major medical problems, microsurgery by an experienced team of surgeons is preferred over radiosurgery.

Saphenous vein graft bypass of the sigmoid sinus and jugular bulb during the removal of glomus jugulare tumors. Report of two cases

Glomus jugulare tumors always invade the jugular bulb and sigmoid sinus, making it difficult to resect these tumors totally without sacrificing the involved sinus. Although the sinus can be sacrificed safely in most patients, a few patients will have serious consequences. Reconstruction of the jugular bulb using a saphenous vein graft may enable tumor resection in these patients without complications. The authors describe two cases of saphenous vein grafting used to bypass the sigmoid sinus. The first case is that of a 61-year-old man with a glomus jugulare tumor that invaded the dominant sigmoid sinus, which was poorly collateralized. Temporary occlusion of the sinus during surgery caused a 15-mm Hg increase in intrasinus pressure, without brain swelling or changes in evoked potentials. A saphenous vein graft was used to bypass the sigmoid sinus and jugular bulb and to allow for total tumor removal. The patient had a good outcome. The second case is that of a 41-year-old man with a left glomus jugulare tumor and another smaller tumor on the opposite, dominant sinus. The left glomus jugulare tumor was resected via a two-stage procedure. A saphenous vein graft was used to reconstruct the left sigmoid sinus because of the presence of contralateral disease, with the potential for bilateral sigmoid sinus occlusion. An evaluation of the venous collateral circulation during jugular foramen surgery and the prevention of complications are also discussed.

Repositioning of the vertebral artery as treatment for neurovascular compression syndromes. Technical note

Neurovascular compression syndromes are usually treated by interposing Teflon felt or padding or some other implant between the offending vessel and the nerves. However, this cannot be done in some cases in which ectatic vertebrobasilar arteries are involved. In these instances, alternative techniques must be used. The authors report the use of a sling made of Prolene to reposition the vertebral artery in two patients with neurovascular compression disorder. The clinical results were gratifying, with complete resolution of the patients' symptoms. Compression by large vessels is an uncommon but important source of neurovascular compression in patients with trigeminal neuralgia, hemifacial spasm, disabling positional vertigo, and, possibly, hypertension. The technique described may be useful to surgeons treating these problems.

EC-IC bypass improves chronic ischemia in a patient with moyamoya disease secondary to sickle cell disease: an in vivo microdialysis study

Patients with sickle cell disease may develop intracranial vascular disease, with the occlusion or obstruction of the large or small arteries, which may lead to the secondary development of moyamoya disease. In this report, we describe the neurochemical changes in the brain before, during, and after an extracranial-intracranial bypass procedure on a patient with sickle cell disease and a moyamoya disease like pattern on angiography. We used the in vivo microdialysis technique to measure the on-line pH, lactate and amino acid concentrations in the extracellular fluid. There were relatively high resting glutamate levels and a lower-than-normal pH in the extracellular fluid prior to the bypass, associated with chronic ischemia. During the bypass there was a short-lived increase in the glutamate levels. After revascularization, there was a rapid decrease in the glutamate levels and an increase in the pH value. The patient's preoperative neurological deficit improved post-operatively, corresponding to the biochemical changes towards normal values. These changes after revascularization suggest that chronic biochemical abnormalities due to brain ischemia may improve after cerebral revascularization.

Long-term follow-up of patients with meningiomas involving the cavernous sinus: recurrence, progression, and quality of life

OBJECTIVE

In this report, we evaluate the recurrence- and progression-free survival of patients with meningiomas involving the cavernous sinus.

METHODS

The rates of tumor recurrence and progression in 119 patients with meningiomas involving the cavernous sinus treated between 1983 and 1993 were analyzed.

RESULTS

The mean follow-up period was 33.8 months. There were seven recurrences of completely resected tumors (7 of 73, 10%) and seven progressions of incompletely resected tumors (7 of 46 15%). Life table analysis of recurrence- and progression-free survival was performed. The recurrence-free survival rate was 94% at 3 years and 81% at 5 years. In contrast, the progression-free survival rate was 87% at 3 years and 62% at 5 years (P = 0.0456). There were two patterns of recurrence or progression. The first group of tumors had an aggressive biological behavior with growth at multiple areas of resection; the second group showed growth at or near the margins of resection. Functional status continued to improve slowly during the follow-up period; however, there was no statistically significant difference between the Karnofsky scores obtained 3 to 12 months postoperatively and the follow-up Karnofsky scores (obtained > 1 yr postoperatively).

CONCLUSION

Surgery for meningiomas involving the cavernous sinus seems to provide excellent tumor control. Our experience suggests that for the majority of these tumors, complete tumor resection can be performed with acceptable risks of morbidity and mortality and seems to increase the duration of recurrence-free survival. The long-term quality of life of surviving patients is satisfactory, with the great majority of the patients being independent.

Enzyme-linked immunosorbent assay quantification of cytokine concentrations in human meningiomas

OBJECTIVE

To gain insight into the network of cytokine gene expression in the brain tumor microenvironment, we investigated the presence of the following cytokines in freshly excised brain tumors: interleukin (IL)-1 beta, IL-2, IL-4, and IL-6.

METHODS

Tumor specimens from nine meningiomas were grown as tissue explants. The supernatants from the explants were tested for the presence of the aforementioned cytokines via the enzyme-linked immunosorbent assay method.

RESULTS

IL-6, which is thought to stimulate acute protein phase synthesis, neovascularization, and cell proliferation, was found in all of the samples in greater concentrations than the other cytokines tested. IL-1 beta, another stimulatory cytokine thought to be involved in acute protein phase synthesis and cell proliferation, was also found in 100% of the samples tested, in concentrations significantly lower than those of IL-6. As expected, the presence of IL-2 and IL-4 was not detectable in any of the samples.

CONCLUSION

This study is the first to clearly determine the relative concentrations of IL-1 beta and IL-6, using enzyme-linked immunosorbent assay quantification. These findings are an important precursor to future studies using antibodies to IL-1 beta and IL-6 and antibodies to IL-6 receptors to modulate neoplastic growth both in vitro and in vivo.

Petroclival and foramen magnum meningiomas: surgical approaches and pitfalls

The management of petroclival and foramen magnum meningiomas has been revolutionized by the techniques of cranial base surgery. However, these tumors are still among the most difficult cranial base lesions to treat. In this report, we discuss the classification, presenting symptoms, preoperative investigation, treatment indications, operative approaches and technique, postoperative complications and care, and results of surgery of petroclival and foramen magnum meningiomas. Careful analysis of tumor- and patient-related factors has helped us to predict which features can lead to postoperative problems in patients allowing surgeons to appropriately modify their behavior. The application of cranial base techniques-combined with new knowledge about the limitations of microsurgical resection-can greatly reduce postoperative morbidity in these patients.

Treatment of aneurysms by excision or trapping with arterial reimplantation or interpositional grafting. Report of three cases

The authors report three cases of ruptured, large or giant aneurysms that were treated by excision or trapping, followed by revascularization of distal vessels by means of arterial reimplantation or superficial temporal artery interpositional grafting. In the first case, a large serpentine aneurysm arising from the anterior temporal branch of the right middle cerebral artery (MCA) was excised and the distal segment of the anterior temporal artery was reimplanted into one of the branches of the MCA. In the second case, a giant aneurysm, fusiform in shape, arose from the rolandic branch of the MCA. This aneurysm was totally excised and the M3 branch in which it had been contained was reconstructed with an arterial interpositional graft. In the third case the patient, who presented with a subarachnoid hemorrhage, had a dissecting aneurysm that involved the distal portion of the left vertebral artery. In this case the posterior inferior cerebellar artery (PICA) arose from the wall of the aneurysm and coursed onward to supply the brainstem. This aneurysm was managed by trapping and the PICA was reimplanted into the ipsilateral large anterior inferior cerebellar artery. None of the patients suffered a postoperative stroke and all recovered to a good or excellent postoperative condition. These techniques allowed complete isolation of the aneurysm from the normal blood circulation and preserved the blood flow through the distal vessel that came out of the aneurysm. These techniques should be considered as alternatives when traditional means of cerebral revascularization are not feasible.