Tumor resection in a shared-resource magnetic resonance operating room: experience at the University of Cincinnati.

INTRODUCTION: At the University of Cincinnati, we have developed a shared-resource magnetic resonance operating suite that facilitates performance of both neurosurgical and diagnostic procedures in a single unit. METHODS: The shared-resource magnetic resonance operating suite utilizes a Hitachi AIRIS II, 0.3-T, vertical field, open MRI unit located in the MROR. This magnet can be used for both diagnostic and interventional procedures. The addition of a rotating-operating table permits neurosurgical procedures to be performed outside of the 5-G line using standard neurosurgical equipment and operating microscopes. RESULTS: We review our results with the shared-resource magnetic resonance operating room including the tabulated results from 30 transsphenoidal procedures and 63 glioma procedures. In addition, 2832 diagnostic procedures have been performed in the first 4 years of use. CONCLUSION: The shared-resource intraoperative MRI facility produces high-quality intraoperative imaging studies, equal to those of high-resolution magnets, and is valuable in enabling the surgeon to achieve the planned degree of resection of glioma and pituitary tumors. The ability to perform diagnostic procedures in a shared unit has been a cost-effective solution for our institution.

Glioma resection in a shared-resource magnetic resonance operating room after optimal image-guided frameless stereotactic resection.

OBJECTIVE: We describe a shared-resource intraoperative magnetic resonance imaging (MRI) design that allocates time for both surgical procedures and routine diagnostic imaging. We investigated the safety and efficacy of this design as applied to the detection of residual glioma immediately after an optimal image-guided frameless stereotactic resection (IGFSR). METHODS: Based on the twin operating rooms (ORs) concept, we installed a commercially available Hitachi AIRIS II, 0.3-tesla, vertical field, open MRI unit in its own specially designed OR (designated the magnetic resonance OR) immediately adjacent to a conventional neurosurgical OR. Between May 1998 and October 1999, this facility was used for both routine diagnostic imaging (969 diagnostic scans) and surgical procedures (50 craniotomies for tumor resection, 27 transsphenoidal explorations, and 5 biopsies). Our study group, from which prospective data were collected, consisted of 40 of these patients who had glioma (World Health Organization Grades II-IV). These 40 patients first underwent optimal IGFSRs in the adjacent conventional OR, where resection continued until the surgeon believed that all of the accessible tumor had been removed. Patients were then transferred to the magnetic resonance OR to check the completeness of the resection. If accessible residual tumor was observed, then a biopsy and an additional resection were performed. To validate intraoperative MRI findings, early postoperative MRI using a 1.5-tesla magnet was performed. RESULTS: Intraoperative images that were suitable for interpretation were obtained for all 40 patients after optimal IGFSRs. In 19 patients (47%), intraoperative MRI studies confirmed that adequate resection had been achieved after IGFSR alone. Intraoperative MRI studies showed accessible residual tumors in the remaining 21 patients (53%), all of whom underwent additional resections. Early postoperative MRI studies were obtained in 39 patients, confirming that the desired final extent of resection had been achieved in all of these patients. One patient developed a superficial wound infection, and no hazardous equipment or instrumentation problems occurred. CONCLUSION: Use of an intraoperative MRI facility that permits both diagnostic imaging and surgical procedures is safe and may represent a more cost-effective approach than dedicated intraoperative units for some hospital centers. Although we clearly demonstrate an improvement in volumetric glioma resection as compared with IGFSR alone, further study is required to determine the impact of this approach on patient survival.

Intraoperative magnetic resonance imaging to determine the extent of resection of pituitary macroadenomas during transsphenoidal microsurgery.

OBJECTIVE: Well-established surgical goals for pituitary macroadenomas include gross total resection for noninvasive tumors and debulking with optic chiasm decompression for invasive tumors. In this report, we examine the safety, reliability, and outcome of intraoperative magnetic resonance imaging (iMRI) used to assess the extent of resection, and thus the achievement of preoperative surgical goals, during transsphenoidal microneurosurgery. METHODS: Our magnetic resonance operating room contains a Hitachi AIRIS II 0.3-T, vertical-field open magnet (Hitachi Medical Systems America, Inc., Twinsburg, OH). A motorized scanner tabletop moves the patient between the imaging and operative positions. For transsphenoidal surgery, the patient is positioned directly on the scanner tabletop so that the surgical field is located between 1.2 and 1.6 m from the magnet isocenter. At this location, the magnetic field strength is low (<20 G), thus permitting the use of many conventional surgical instruments. Thirty consecutive patients with pituitary macroadenomas underwent tumor resection in our magnetic resonance operating room by use of a standard transsphenoidal approach. After initial resection, the patient was advanced into the scanner for imaging. If residual tumor was demonstrated and deemed surgically accessible, the patient underwent immediate re-exploration. RESULTS: iMRI was performed successfully in all 30 patients. In one patient, iMRI was used to clarify the significance of hemorrhage from the sellar region and resulted in immediate conversion of the procedure to a craniotomy. In the remaining 29 patients, initial iMRI demonstrated that the endpoint for extent of resection had been achieved in only 10 patients (34%) after an initial resection attempt, whereas 19 patients (66%) still had unacceptable residual tumor. All 19 of these latter patients underwent re-exploration. Ultimately, re-exploration resulted in the achievement of the planned endpoint for extent of resection in all of the 29 completed transsphenoidal explorations. Operative time was extended in all cases by at least 20 minutes. CONCLUSION: iMRI can be used to safely, reliably, and objectively assess the extent of resection of pituitary macroadenomas during the transsphenoidal approach. The surgeon is frequently surprised by the extent of residual tumor after an initial resection attempt and finds the intraoperative images useful for guiding further resection.

Honored guest presentation: therapeutic decisions in facial pain.

The authors recommend a multidisciplinary approach for the diagnosis and treatment of facial pain. With this approach, several experts can accurately diagnose various disorders of facial pain and offer appropriate treatment options, which should be tailored to the specific needs and general condition of the patient. For reporting and comparison, seek standardization of methods of analysis and outcomes criteria. Associate with a good secretary and nurse. For your patients' benefit, be an optimistic, caring, and attentive listener.

Petroclival meningiomas: predictive parameters for transpetrosal approaches.

OBJECTIVE: To determine parameters that influence the selection of the proper petrosal approach or combined approaches for the excision of petroclival meningiomas. METHODS: We dissected 15 cadaver heads, inspected the petroclival region in 50 dry human skulls, and performed a retrospective analysis of the cases of 35 patients with petroclival meningiomas who underwent surgery via transpetrosal approaches. RESULTS: The petroclival region was divided into three "zones" based on the extent of surgical exposure achieved via the petrosal approaches with microscopic dissection of 15 preserved and silicone-injected cadaveric heads and with the measurements of 50 dry skulls. Zone I, defined as the area from the dorsum sellae to the internal auditory canal, is accessible via the anterior petrosal approach. Zone II, defined as the area from the internal auditory canal to the upper border of the jugular tubercle, is easily accessible in its lateral portion via the posterior petrosal approach. The medial portion of Zone II, the "central clival depression," is accessible only with cochlear resection and posterior facial nerve transposition. Zone III, defined as the area from the upper border of the jugular tubercle to the lower edge of the foramen magnum, is accessible via a suboccipital/transcondylar approach. The retrospective analysis of the cases of 35 patients who underwent transpetrosal resection of petroclival meningiomas between 1991 and 1998 was used to determine the predictive value of these anatomic parameters. The degree of tumor resection was analyzed with a novel grading scale combining the percentage of resection and the percentage of brainstem reexpansion. Total excision was achieved in 37% of the patients and complete brainstem reexpansion was achieved in an additional 40%. Residual tumor was concentrated in the central clival depression in Zone II, as predicted by anatomic parameters, and around infiltrated neurovascular structures. New cranial nerve deficit occurred in 31% of the patients in the early postoperative period and improved to 17% at 6 months. Major morbidity occurred in 9% of the patients, and mortality was 0%. Early Karnofsky scores were reduced in 37% of the patients, but 6-month Karnofsky scores were equal to preoperative baseline scores or improved in 91%. CONCLUSION: Anatomic parameters can predict the resectability of petroclival meningiomas. Judicious application of cytoreductive surgery in selected patients maintains an acceptable morbidity and achieves adequate brainstem reexpansion.

Permanent iodine-125 interstitial implants for the treatment of recurrent glioblastoma multiforme.

OBJECTIVE: Brachytherapy with temporary implants may prolong survival in patients with recurrent glioblastoma multiforme (GBM), but it is associated with relatively high costs and morbidity. This study reports the time to progression and survival after permanent implantation of iodine-125 seeds for recurrent GBM and examines factors predictive of outcome. METHODS: Forty patients with recurrent GBM were treated with maximal resection plus permanent placement of iodine-125 seeds into the tumor bed. A total dose of 120 to 160 Gy was administered, and patients were followed up with magnetic resonance imaging scans every 2 to 3 months. RESULTS: Actuarial survival from the time of implantation was 47 weeks, with 7 of 40 patients still alive at a median of 59 weeks after implantation. Survival was significantly better for patients younger than 60 years, and a trend for longer survival was demonstrated with gross total resection and tumors with a low MIB-1 (a nuclear antigen present in all cell cycles of proliferating cells) staining index. Median time to progression was 25 weeks and, on multivariate analysis, was favorably influenced by gross total resection and patient age younger than 60 years. After implantation, 27 of 30 patients with failure had a local component to the failure. No patient developed symptoms attributable to radiation necrosis or injury. CONCLUSION: Permanent iodine-125 implants for recurrent GBM result in survival comparable with that described in previous reports on temporary implants, but with less morbidity. Results are most favorable for patients who are younger than 60 years, and who undergo gross total resection. Despite this aggressive treatment, most patients die as a consequence of locally recurrent disease.

Pure sylvian fissure arteriovenous malformations.

OBJECT: Pure sylvian fissure arteriovenous malformations (AVMs) are vascular malformations confined to the sylvian fissure without parenchymal involvement. Because the branches of the middle cerebral artery are arteries of passage and the margins between the AVM and the insula cortex may be ill defined, many surgeons regard pure sylvian fissure AVMs as inoperable. The authors reviewed their surgical experience with eight patients harboring pure sylvian fissure AVMs to determine the incidence of operative morbidity. METHODS: All eight patients experienced seizures, five (63%) had headaches, and three (38%) experienced hemorrhages. Preoperatively, six patients (75%) were normal neurologically and two (25%) had neurological deficits. Five (63%) of eight sylvian fissure AVMs were located in the dominant hemisphere. The size of the nidus ranged from 6 to 27 cm3 (mean 14 cm3). Complete removal of the AVM was documented by postoperative angiography in every case. Seizures were reduced or eliminated and headaches were relieved in all affected patients. Transient neurological deficits, which included aphasia, short-term memory loss, and hemiparesis, occurred in four patients (50%). Within 3 months, all patients were functioning independently with no new neurological deficits. The status of two patients who had had preoperative neurological deficits improved postoperatively. Neuropsychological testing showed no new cognitive deficits. CONCLUSIONS: With appreciation for transient instances of postoperative morbidity, the outcome was excellent in all patients. The authors thus advocate microsurgery as the primary treatment for pure sylvian fissure AVMs.

M. Gazi Yasargil: Neurosurgery's man of the century.

Dissatisfied with the available macrosurgical techniques and encouraged by colleagues such as Donaghy and Krayenbühl, M. Gazi Yasargil possessed the ingenuity to take advantage of and further improve emerging technologies such as angiography to develop microsurgery. To enable the advancement of microsurgical techniques, Yasargil created innovative instrumentation, such as the floating microscope, the self-retaining adjustable retractor, microsurgical instruments, and ergonomic aneurysm clips and appliers. His genius in developing microsurgical techniques for use in cerebrovascular neurosurgery has transformed the outcomes of patients with conditions that were previously inoperable.

Utility, safety, and accuracy of intraoperative angiography in the surgical treatment of aneurysms and arteriovenous malformations.

BACKGROUND AND PURPOSE: The role of intraoperative angiography in the treatment of neurovascular lesions has remained extremely controversial. We retrospectively reviewed the utility, safety, and accuracy of intraoperative angiography to ascertain its effect on the treatment of patients with neurovascular lesions. METHODS: We reviewed the results of intraoperative angiography in 91 patients treated surgically for intracranial aneurysms and in 98 patients treated surgically for arteriovenous malformations (AVMs). All treatments were completed at two major teaching hospitals between October 1987 and March 1995. RESULTS: The initial angiographic findings caused the surgical procedure to be modified in 24 (26%) of the patients with aneurysms and in 28 (29%) of the patients with AVMs. Analysis of the final angiographic sequence showed residual lesions in nine (10%) of the aneurysm cases and in eight (8%) of the AVM cases. The imperfect angiographic results were deemed acceptable because there was either evidence of collateral flow when the parent vessel was occluded or the risk of further surgical modification was considered more dangerous than the abnormality itself. Seven patients suffered complications, of which only one had permanent neurologic sequelae: a CNS complication rate of 0.5%. Comparison of the intraoperative angiographic findings with those of postoperative studies revealed four false-negative results (5.2%). CONCLUSION: Intraoperative angiography is an important component in the treatment of patients with intracranial vascular lesions. It is effective and can be carried out with low risk in this patient population.

Dural sinus thrombosis and pseudotumor cerebri: unexpected complications of suboccipital craniotomy and translabyrinthine craniectomy.

OBJECT: The goal of this study was to document the hazards associated with pseudotumor cerebri resulting from transverse sinus thrombosis after tumor resection. Dural sinus thrombosis is a rare and potentially serious complication of suboccipital craniotomy and translabyrinthine craniectomy. Pseudotumor cerebri may occur when venous hypertension develops secondary to outflow obstruction. Previous research indicates that occlusion of a single transverse sinus is well tolerated when the contralateral sinus remains patent. METHODS: The authors report the results in five of a total of 107 patients who underwent suboccipital craniotomy or translabyrinthine craniectomy for resection of a tumor. Postoperatively, these patients developed headache, visual obscuration, and florid papilledema as a result of increased intracranial pressure (ICP). In each patient, the transverse sinus on the treated side was thrombosed; patency of the contralateral sinus was confirmed on magnetic resonance (MR) imaging. Four patients required lumboperitoneal or ventriculoperitoneal shunts and one required medical treatment for increased ICP. All five patients regained their baseline neurological function after treatment. Techniques used to avoid thrombosis during surgery are discussed. CONCLUSIONS: First, the status of the transverse and sigmoid sinuses should be documented using MR venography before patients undergo posterior fossa surgery. Second, thrombosis of a transverse or sigmoid sinus may not be tolerated even if the sinus is nondominant; vision-threatening pseudotumor cerebri may result. Third, MR venography is a reliable, noninvasive means of evaluating the venous sinuses. Fourth, if the diagnosis is made shortly after thrombosis, then direct endovascular thrombolysis with urokinase may be a therapeutic option. If the presentation is delayed, then ophthalmological complications of pseudotumor cerebri can be avoided by administration of a combination of acetazolamide, dexamethasone, lumbar puncture, and possibly lumboperitoneal shunt placement.

A comparison between endovascular and surgical management of basilar artery apex aneurysms.

OBJECT: The goal of this retrospective study was to evaluate endovascular treatment by means of Guglielmi detachable coils (GDCs) compared with surgical management for basilar artery (BA) apex aneurysms. METHODS: Forty-one patients presented with saccular BA apex aneurysms with angiographically definable necks that were judged suitable for either treatment. Of 20 patients who underwent surgery and 21 who underwent GDC embolization, 15 (75%) and 11 (52%), respectively, were treated in the acute phase after subarachnoid hemorrhage (SAH). Twenty-four (92%) of the 26 patients presenting with an SAH had a Hunt and Hess Grade III or better. Fifteen patients with unruptured or ruptured aneurysms more than 14 days post-SAH were treated electively. Patients in the endovascular and surgical treatment groups had aneurysms with comparable dimensions and configurations. Overall, 15 (75%) of the surgical patients and 20 (95%) of the patients in whom GDC embolization was performed had a good outcome (Glasgow Outcome Scale score of 4 or 5). Among those patients treated in the acute stage post-SAH, 11 (73%) of the surgical group and 10 (91%) of the endovascular group did well. Fourteen patients treated electively (93%) had good outcomes. There were two deaths (10%) in the surgical group and none in the endovascular group. Patients treated surgically were hospitalized twice as long and incurred twice the expenses of patients who underwent endovascular treatment (p<0.001). CONCLUSIONS: Endovascular GDC embolization of select BA apex aneurysms may be a competitive alternative to direct surgical clipping. Long-term follow up is needed to better define the natural history of the endovascularly treated aneurysm and to further evaluate the accuracy of these preliminary results.

Trigeminal schwannomas: the role of the neurotologist in multidisciplinary management.

Trigeminal neuromas are slow-growing benign tumors representing approximately 10% of all intracranial neuromas and less than 0.5% of all intracranial tumors. Historically, excision of these tumors through traditional neurosurgical routes--including the frontotemporal transsylvian, subtemporal-intradural, subtemporal-transtentorial, or suboccipital approaches--has resulted in an unsatisfactorily high rate of recurrence. In this study we compare contemporary skull base/neurotologic approaches with conventional procedures for trigeminal neuroma extirpation.

Compression of the upper cervical spinal cord causing symptoms of brainstem compromise. A case report.

STUDY DESIGN: A case is reported in which a flexion-induced compression of the upper cervical spinal cord caused symptoms of brainstem compromise in the absence of radiographic evidence of osseous instability. OBJECTIVES: A 41-year-old woman developed postoperative cervical instability with flexion-induced neurologic symptoms referable to the brainstem. The instability was caused by direct compression at the third cervical vertebral body, which in turn was caused by differential movements between the neuraxis and skeletal elements in the upper cervical spine. SUMMARY OF BACKGROUND DATA: Pathologic processes at the craniocervical junction may cause brainstem compromise with neurologic symptoms. The mechanism of brainstem involvement is usually either vertebrobasilar insufficiency or direct mechanical compression. In cases where the brainstem is compressed by skeletal elements, the compressing osseous structures usually are the walls of the foramen magnum or the odontoid process, or, less frequently, the atlas or axis vertebrae. Symptoms of brainstem dysfunction caused by dynamic compression at the level of the third cervical vertebra in the absence of hindbrain herniation are unusual and, to the best of the authors' knowledge, have not been described previously. METHODS: The patient underwent initial examination, evaluation, and periodic follow-up examination with magnetic resonance imaging from the time of her first visit until 26 months after the surgical treatment. The patient experienced postsurgical instability with dynamic compression by the C3 vertebral body, which caused brainstem compromise. Surgical treatment consisted of decompressive C3 corpectomy and fusion of C2 to C6, supplemented by anterior fixation. RESULTS: After undergoing surgical decompression of C3, reconstruction, and anterior internal fixation of C2 to C6, the patient had dramatic neurologic improvement. Diplopia, paresthesia, and nystagmus disappeared immediately after surgery. Swallowing difficulties, hoarseness, and vertigo improved gradually. At follow-up examination 26 months after surgery, the patient was asymptomatic. Magnetic resonance imaging showed good position of the construct, with no evidence of compression of the spinal cord or brainstem. CONCLUSIONS: Instability of the cervical spine may result in symptoms of brainstem dysfunction, even in the absence of hindbrain herniation. This instability is explained by the differential movement between the bony structures and neuraxis in the upper cervical region. Diagnosis and adequate management of this instability alleviates the neurologic symptoms and prevents possible hazardous complications.

Combined interventional and surgical treatment of arteriovenous malformations.

This article describes the combined interventional and surgical treatment of arteriovenous malformations. The development of embolization as an adjunct to microsurgical resection of arteriovenous malformations has expanded the therapeutic armamentarium in the treatment of these lesions. Patient selection, indications, technical aspects as well as avoidance and treatment of complications with regard to endovascular embolization are discussed. Four individual cases are presented to show how embolization can be combined with microsurgery to achieve optimal treatment results.

Formation of intracerebral cavernous malformations after radiation treatment for central nervous system neoplasia in children.

OBJECT: Radiation is a common treatment modality for pediatric brain tumors. The authors present a retrospective review of six children who developed cerebral cavernous malformations after they underwent radiation treatment for central nervous system (CNS) neoplasia and propose two possible models to explain the formation of cavernous malformations. METHODS: Three boys, aged 13, 9, and 17 years, suffered intracerebral hemorrhages from cerebral cavernous malformations 87, 94, and 120 months, respectively, after they received whole-brain radiation therapy (WBRT) for acute lymphocytic leukemia. A 10-year-old girl and a 19-year-old man developed temporal lobe cavernous malformations 46 and 48 months, respectively, after they received radiation therapy for posterior fossa astrocytomas. A 12-year-old girl developed a temporal lobe cavernous malformation 45 months after WBRT was administered for a medulloblastoma. In all of these cases the cavernous malformation appeared in the irradiated field, was not known to be present prior to radiation therapy, and developed after a latency period following treatment. The incidence of cavernous malformations in these patients suggests that children who undergo radiation therapy of the brain may have an increased risk of hemorrhage. CONCLUSIONS: Two possible models may explain the formation of cavernous malformations following brain radiation in these patients. First, the cavernous malformations may form de novo in response to the radiation. Second, the cavernous malformations may have been present, but radiographically occult, at the time of radiation therapy and may have hemorrhaged in response to the radiation. The authors conclude that cavernous malformations may develop after brain radiation and propose a possible mechanism for this formation.

Surgical management of deep-seated dural arteriovenous malformations.

The best treatment for deep-seated dural arteriovenous malformations (AVMs) remains controversial. Therapeutic options include transarterial and transvenous embolization, surgical excision of the dural nidus, ligation of draining veins, and stereotactically guided radiation treatment. The authors report on their experience with the application and technique of skull base surgical approaches for deep-seated dural AVMs. Their series includes six patients who were surgically treated for five tentorial dural AVMs and one inferior petrosal sinus dural AVM between 1991 and 1995. Three patients presented with progressive brainstem dysfunction, one had progressive myelopathy, and two suffered subarachnoid hemorrhage. Venous hypertension caused progressive neurological deterioration in four patients and ruptured venous aneurysms caused hemorrhage in two patients. Four of the five tentorial dural AVMs received bilateral arterial supply from the internal carotid arteries and external carotid arteries (ECAs). The dural AVM of the inferior petrosal sinus was fed from both vertebral arteries and ECAs. In this series, all dural AVMs drained into deep cerebral veins. Intra- and postoperative angiographic studies were used to document complete obliteration in each case. After surgery, three patients developed transient, delayed (24-72 hours) neurological worsening. One month postsurgery, all six patients showed improvement from their preoperative neurological function. Surgical resection of these deep-seated dural AVMs was accomplished by eliminating the arterial supply rather than ligating the draining veins to avoid aggravating the underlying venous hypertension. This study demonstrates an important role for skull base surgical approaches in the management of patients with deep-seated dural AVMs that have hemorrhaged, are not obliterated by embolization, and for which stereotactically guided radiation therapy is an unsuitable option.