Linac radiosurgery for skull base meningiomas.

INTRODUCTION: Skull base meningiomas present a difficult surgical challenge because of the high potential morbidity of radical surgical extirpation and their low potential for incapacitating symptomatology. The focal character of meningiomas makes stereotactic radiosurgery an attractive adjuvant treatment modality to resection. The purpose of this study was to evaluate the local control rates and complications in 56 patients with base of skull meningiomas undergoing radiosurgery. METHODS: Patients underwent radiosurgery using the dedicated stereotactic linear accelerator at the Brigham and Women's Hospital. Minimal peripheral doses of radiosurgery ranged from 12 to 18.5 Gy (mean 15 Gy). Doses were designed to conform to the frequently irregular tumor volumes using the X-Knife treatment planning system. Multiple isocenters were used when required to increase conformality of dose. For 36 patients (64%), radiosurgery was used as an adjunct to surgery; for 20 patients (36%) it was the primary treatment. RESULTS: Median followup was five years. Nineteen patients (34%) were improved clinically at follow-up; 32 (57%) were unchanged; and 5 patients (9%) developed new or worsened neurologic deficits. Serial imaging studies after radiosurgery showed a reduction in tumor volume in 23 patients (41%); 30 (54%) showed stable disease; 3 patients (5%) had tumors which increased in size (2 being outside the radiosurgery treatment site). The actuarial freedom from progression rate (defined as further tumor growth) was thus 95%, with a median imaging follow-up of 26 months (range, 6-66 months). Although further follow-up is necessary, the results of this series clearly demonstrate that these lesions are feasible for treatment by modern radiosurgical techniques. Linac radiosurgery can stabilize skull base meningiomas, with decreased or unchanged tumor volumes on radiologic follow-up in approximately 95% of patients. Radiosurgery is a low-morbidity, effective technique as adjunct and sometimes primary treatment of small to moderate-sized meningiomas of the skull base.

Aggressive surgery and focal radiation in the management of meningiomas of the skull base: preservation of function with maintenance of local control.

BACKGROUND: Recent study series have reported that post-operative external beam radiation therapy and stereotactic radiosurgery with the linear accelerator or gamma knife improves long-term local control of subtotally resected or recurrent meningiomas. METHODS: Analysis of treatment results in 100 consecutive patients with skull base meningiomas managed by one surgeon with a median follow-up of five years. Treatment principles included observation for asymptomatic tumors; surgery for progressive or symptomatic tumors unless surgery was medically contraindicated or refused by the patient; to make surgery as aggressive as possible but with the goal of preserving full function of the patient; and to use radiosurgery or conformal fractionated radiation therapy if residual tumor was demonstrated. Preoperative, postoperative, and observational data were prospectively accumulated and stored in a large database system. Median follow up was 5 years with a range from 2 to 10 years. FINDINGS: The most frequent presenting symptoms were headache (45%) and changes in vision (29%). Cranial nerve deficits (49%) and cerebellar signs (24%) were the most common physical findings. Seventy-two patients had surgical resection. Of these, 93% had greater than 50% resection and 47% had radiographically complete resection. There were no perioperative deaths and there were five surgical complications for a rate of 7%. Complications included hemiparesis (2.8%), new cranial nerve palsy (2.8%), and indolent osteomyelitis (1.4%). Fifteen patients had observation only; none of who progressed. Thirteen patients had radiation only, primarily because of patient preference or medical contraindications to surgery in the setting of substantial symptoms. There were no complications of this therapy. With a median five-year follow-up, only one patient (1%) demonstrated tumor progression using the treatment paradigm outlined here. INTERPRETATION: These results demonstrate that skull base meningiomas which require treatment can be managed with a combination of aggressive surgery and conformal radiation with an acceptable functional status in 99% of cases.

Utility of three-dimensional computed tomographic angiography for assessment of relationships between the vertebrobasilar system and the cranial base.

OBJECTIVE: The optimal surgical exposure for basilar tip aneurysms is dictated by the relationship of the basilar bifurcation to the cranial base. This study was designed to evaluate three-dimensional computed tomographic angiography as a means of obtaining detailed anatomic information on the basilar artery and the surrounding cranial base in individual patients before surgery. METHODS: We studied 30 patients using three-dimensional computed tomographic angiographic reconstructions from 1-mm computed tomographic slices. Detailed anatomic measurements were performed to define the relationship between the basilar artery and the cranial base. Particular attention was paid to the height of the dorsum sellae and its relationship to the basilar bifurcation. RESULTS: The heights of the basilar apex and the vertebrobasilar junction, relative to the cranial base, were extremely variable. Considerable asymmetries in the heights of the left and right posterior clinoid processes were identified; in one case, this difference was more than 1 cm (mean difference in height, 0.9 mm; range, 0-10.3 mm). The heights of the posterior clinoid processes above the sellar floor ranged from 5.8 to 14.1 mm (mean height, 9.5 mm). We were able to determine the feasibility of the pterional/orbitozygomatic, middle fossa/ anterior petrosal, and presigmoid retrolabyrinthine approaches to an individual basilar bifurcation. We also estimated the amount of bone removal required and determined the operative distances via those approaches. CONCLUSION: Three-dimensional computed tomographic angiography is a useful tool for assessing critical anatomic relationships and represents an adjunct to conventional angiography in the planning of individualized, precisely tailored, cranial base approaches to the vertebrobasilar system.

Management of acute cervical spinal cord injury.

BACKGROUND: Spinal cord injury affects approximately 10,000 new persons each year in the United States. Motor vehicle crashes, violence, and falls are the most common causes. The purpose of this review is to provide a rational management strategy for treating acute cervical spinal cord injuries. REVIEW SUMMARY: History-taking in these patients should focus on a few key points. Physical examination consists of determining the level of the lesion by a tailored motor, sensory, and reflex examination. An algorithm for the judicious use of plain radiographs, computed tomography scans, and emergent magnetic resonance imaging is presented. Management goals include protection of uninjured tissue, restoration of reversibly injured tissue, and achieving alignment and permanent spinal stability. The role of early surgery and high-dose steroids are discussed. CONCLUSION: Maximizing neurological function after cervical spinal cord injuries relies on rapid diagnosis and appropriate management. Although prognosis generally remains poor, recent advances in the basic sciences offer hope for the future.

Clinical outcome differences for lipomyelomeningoceles, intraspinal lipomas, and lipomas of the filum terminale.

Failure to differentiate between the different types of lumbosacral lipomas may lead to inaccurate assumptions and inappropriate management of patients. The goal of this study was to determine whether there is a difference in clinical outcome between patients with lipomyelomeningocles, intraspinal lipomas, and lipomas of the filum terminale. One hundred and fourteen patients with spinal dysraphism were seen at Duke University Medical Center between 1995-1999. All patients who had undergone previous operative intervention for these lesions were excluded. Twenty-two patients with intradural lipomas were identified. Of these, 14 (64%) had lipomyelomeningoceles and 8 (36%) had intraspinal lipomas. Twenty-five patients had filum terminale lipomas. Operative management consisted of lumbosacral laminectomies with microsurgical resection of the lipoma and division of the fatty filum. Average age at presentation in symptomatic patients with lipomas of the filum terminale was 17.7 years, and 23 years in the symptomatic intraspinal lipoma group. Patients with lipomyelomeningoceles ranged in age from 1 day to 18 years, with the majority being younger than 2 years. After an average follow-up of 8 months all patients showed improvement in motor strength following operative intervention. Greater improvements in sensory, bladder, and pain scores were associated with filum terminale lipomas. The least improvements in these categories were seen in the lipomyelomeningocele group. Motor strength is the most likely deficit to improve following operative intervention. Lipomyelomeningoceles, intraspinal lipomas, and filum termniale lipomas have different clinical outcomes following operative intervention.

Treatment of neoplastic meningitis with intrathecal temozolomide.

Neoplastic meningitis (NM) results from leptomeningeal dissemination of cancers arising within the central nervous system or metastasizing to the leptomeninges from systemic neoplasms. The inability to produce therapeutic drug levels intrathecally (i.t.) with systemic administration and the minimal efficacy of chemotherapeutic agents currently available for direct i.t. use limit therapy. Temozolomide [8-carbamoyl-3-methylimidazo[5,1-d]-1,2,3,5-tetrazin-4([3H])-one] is a novel methylating agent with proven activity against intraparenchymal malignant gliomas (MGs). Insolubility of the standard formulation prevents its efficacious use as an i.t. agent, however. To overcome this obstacle, we have developed a unique microcrystalline formulation of temozolomide with greatly enhanced solubility. Treatment of athymic rats bearing subarachnoid MER- human MG xenografts with four doses of i.t. microcrystalline temozolomide over a 2-week period produced a 142% increase in median survival at individual doses of 2.2 micromol (P = 0.0073) and a >367% increase in median survival at individual doses of 6.8 micromol (P = 0.0015). At the higher dose tested, three of eight rats treated developed no neurological symptoms and had no evidence of residual tumor on histological examination after treatment. Use of this microcrystalline formulation in athymic rats bearing subarachnoid MER+ human MG xenografts increased median survival >132% (P < 0.0058) at both dose levels tested. Toxicity directly attributable to the i.t. administration of microcrystalline temozolomide was exhibited in the highest dose groups only and was limited to small patchy areas of focal demyelination involving <5% of spinal cord long tracks.

Avoiding complicated shunt systems by open fenestration of symptomatic fourth ventricular cysts associated with hydrocephalus.

Optimal treatment of the hydrocephalic patient with symptomatic Dandy-Walker malformation or trapped fourth ventricle remains controversial. We describe 6 patients with symptomatic Dandy-Walker malformation or trapped fourth ventricle and hydrocephalus that were treated with an aggressive cyst fenestration. Four of the 6 patients had previously undergone five or more failed shunt procedures. There were no complications associated with surgery, and 5 of the 6 patients (83%) have remained asymptomatic with respect to their posterior fossa cysts. One patient has required subsequent fourth ventricular shunt placement. Median follow-up was 26 months (range 12-66 months). We suggest that suboccipital craniectomy and open fenestration is a valid treatment option in hydrocephalic patients with symptomatic Dandy-Walker malformation or trapped fourth ventricle. Although the associated lateral ventriculomegaly will probably still require a ventriculoperitoneal shunt, the absence of a cystoperitoneal shunt system seems to minimize the incidence of complications and reoperation.