Stereotactic radiosurgery for meningiomas

The indications for and results after meningioma radiosurgery results are discussed. Particular emphasis is placed on longer-term results, the evolution of technique, complications, and recommendations regarding the role of radiosurgery together with other management strategies.

Stereotactic radiosurgery for anterior foramen magnum meningiomas

BACKGROUND

Total microsurgical resection is the procedure of choice for growing and symptomatic foramen magnum meningiomas. We hypothesized that for patients with advanced age, complicating medical conditions, or residual or recurrent meningiomas at the foramen magnum, stereotactic radiosurgery would be a useful adjunctive (n = 2) or alternative (n = 3) treatment.

METHODS

We report our experience in five elderly patients (73-84 years) who underwent gamma knife radiosurgery. The median tumor volume was 10.5 ml and the tumor margin dose varied from 10 to 16 Gy. Because of the irregular tumor volumes along the inferior clivus, multiple isocenters of irradiation were required (range, 2-8; mean 4.4).

RESULTS

During the follow-up interval of 1-5 years (median, 3 years), one patient died of an intercurrent illness, and all remaining patients were stable without any further deterioration in their clinical condition. Follow-up imaging studies revealed a reduction in tumor volume in one patient and no further growth in the remaining four.

CONCLUSION

We believe that stereotactic radiosurgery provides safe and effective management for patients who are poor candidates for resection of their foramen magnum meningiomas.

Outcomes after stereotactically guided pallidotomy for advanced Parkinson's disease

OBJECT

Parkinson's disease (PD) is a prevalent neurodegenerative disorder that becomes refractory to medication as the disease progresses. Although in the past 5 years increasing numbers of patients have undergone stereotactically guided posteroventral pallidotomy for advanced PD, the safety and efficacy of surgery remains to be documented. The goal in this study was to determine the potential operative morbidity and types of functional outcomes by using validated PD rating scales and a patient survey.

METHODS

In a prospective analysis of a consecutive surgical series the authors evaluated 58 patients with advanced PD who ranged in age from 40 to 79 years (mean 67 years) and who had undergone surgery between 1994 and 1997. They used a patient survey and the Unified Parkinson's Disease Rating Scale (UPDRS) to study patients during periods of medication administration ("on") and withdrawal ("off"; mean off score before surgery = 96). Temporary surgical morbidity was found in four patients (6.9%), three of whom developed transient dysarthria and one of whom exhibited transient confusion (1.7%). One patient had persistent dysarthria (1.7%). No patient developed a visual field deficit or sustained a brain hemorrhage. All patients were discharged from the hospital within 24 hours. Significant postsurgical improvements were noted in the UPDRS off-period total and motor scores, as well as in tremor, rigidity, bradykinesia, and contralateral dyskinesia (p < 0.005). Improvements persisted in dyskinesia and tremor for the 21 patients who were evaluated past 1 year. The authors found no improvement in any on-period symptoms except dyskinesia. Thirty-one (61 %) of 51 patients surveyed reported functional gains and/or dramatic improvement in symptoms, 17 (33%) reported symptomatic improvement without functional gains, and three (6%) had minimal or no change in symptoms. No change in the mini mental state examination score was noted during follow up. There were no significant postoperative changes in the use of medication.

CONCLUSIONS

In advanced PD associated with either a medically refractory state with significant off periods or levodopa-induced dyskinesias, magnetic resonance imaging-guided pallidotomy with macrostimulation was associated with minimal morbidity and yet significantly reduced dyskinesia and off-period disability. These improvements were of value to the patient and persisted beyond the 1st year.

Vestibular schwannoma management. Part I. Failed microsurgery and the role of delayed stereotactic radiosurgery

OBJECT

The purpose of this study was to analyze patient outcomes and to define the role of radiosurgery in patients who have undergone prior microsurgical resection of their vestibular schwannoma.

METHODS

The authors evaluated the pre- and postoperative clinical and neuroimaging characteristics of 76 consecutive patients with 78 vestibular schwannomas who underwent radiosurgery after previous surgical resection. Twenty-nine patients (37% of tumors) had undergone more than one prior resection. Forty-three patients (55% of tumors) had significant impairment of facial nerve function (House-Brackmann Grades III-VI) after their microsurgical procedure; 50% had trigeminal sensory loss, and 96% had poor speech discrimination (< 50%). The median evaluation period following radiosurgery was 43 months (range 12-101 months). Tumor growth control after radiosurgery was achieved in 73 tumors (94%). Six patients underwent additional surgical resection despite radiosurgery (median of 32 months after radiosurgery), and one patient underwent repeated radiosurgery for tumor progression outside the irradiated volume. Eleven (23%) of 47 patients with Grades I to III facial function before radiosurgery developed increased facial weakness after radiosurgery. Eleven patients (14%) developed new trigeminal symptoms.

CONCLUSIONS

Radiosurgery proved to be a safe and effective alternative to additional microsurgery in patients in whom the initial microsurgical removal failed. Stereotactic radiosurgery should be considered for all patients who have regrowth or progression of previously surgically treated vestibular schwannomas.

Vestibular schwannoma management. Part II. Failed radiosurgery and the role of delayed microsurgery

OBJECT

The indications, operative findings, and outcomes of vestibular schwannoma microsurgery are controversial when it is performed after stereotactic radiosurgery. To address these issues, the authors reviewed the experience at two academic medical centers.

METHODS

During a 10-year interval, 452 patients with unilateral vestibular schwannomas underwent gamma knife radiosurgery. Thirteen patients (2.9%) underwent delayed microsurgery at a median of 27 months (range 7-72 months) after they had undergone radiosurgery. Six of the 13 patients had undergone one or more microsurgical procedures before they underwent radiosurgery. The indications for surgery were tumor enlargement with stable symptoms in five patients, tumor enlargement with new or increased symptoms in five patients, and increased symptoms without evidence of tumor growth in three patients. Gross-total resection was achieved in seven patients and near-gross-total resection in four patients. The surgery was described as more difficult than that typically performed for schwannoma in eight patients, no different in four patients, and easier in one patient. At the last follow-up evaluation, three patients had normal or near-normal facial function, three patients had moderate facial dysfunction, and seven had facial palsies. Three patients were incapable of caring for themselves, and one patient died of progression of a malignant triton tumor.

CONCLUSIONS

Failed radiosurgery in cases of vestibular schwannoma was rare. No clear relationship was demonstrated between the use of radiosurgery and the subsequent ease or difficulty of delayed microsurgery. Because some patients have temporary enlargement of their tumor after radiosurgery, the need for surgical resection after radiosurgery should be reviewed with the neurosurgeon who performed the radiosurgery and should be delayed until sustained tumor growth is confirmed. A subtotal tumor resection should be considered for patients who require surgical resection of their tumor after vestibular schwannoma radiosurgery.

Gamma knife radiosurgery for trigeminal neuralgia: results and expectations

BACKGROUND

Trigeminal neuralgia is a disabling pain syndrome responsive to both medical and surgical therapies. Stereotactic radiosurgery using the gamma knife can be used to inactivate a specified volume in the brain by cross firing 201 photon beams. We evaluated pain relief and treatment morbidity after trigeminal neuralgia radiosurgery.

METHODS

All evaluable patients (n = 106) had medically or surgically refractory trigeminal neuralgia. A single 4-mm isocenter of radiation was focused on the proximal trigeminal nerve just anterior to the pons. For follow-up an independent physician who was unaware of treatment parameters contacted all patients.

RESULTS

After radiosurgery, 64 patients (60%) became free of pain and required no medical therapy (excellent result), 18 (17%) had a 50% to 90% reduction (good result) in pain severity or frequency (some still used medications), and 9 (9%) had slight improvement. At last follow-up (median, 18 months; range, 6-48 months), 77% of patients maintained significant relief (good plus excellent results). Only 6 (10%) of 64 patients who initially attained complete relief had some recurrent pain. Radiosurgery dose (70-90 Gy), age, surgical history, or facial sensory loss did not correlate with pain relief. Poorer results were found in patients with multiple sclerosis. Twelve patients developed new or increased facial paresthesias after radiosurgery (10%). No patient developed anesthesia dolorosa. There was no other procedural morbidity.

CONCLUSIONS

Gamma knife radiosurgery is a minimally invasive technique to treat trigeminal neuralgia. It is associated with a low risk of facial paresthesias, an approximate 80% rate of significant pain relief, and a low recurrence rate in patients who initially attain complete relief. Longer-term evaluations are warranted.

Long-term outcomes after radiosurgery for acoustic neuromas

BACKGROUND

Stereotactic radiosurgery is the principal alternative to microsurgical resection for acoustic neuromas (vestibular schwannomas). The goals of radiosurgery are the long-term prevention of tumor growth, maintenance of neurologic function, and prevention of new neurologic deficits. Although acceptable short-term outcomes have been reported, long-term outcomes have not been well documented.

METHODS

We evaluated 162 consecutive patients who underwent radiosurgery for acoustic neuromas between 1987 and 1992 by means of serial imaging tests, clinical evaluations, and a survey between 5 and 10 years after the procedure. The average dose of radiation to the tumor margin was 16 Gy, and the mean transverse diameter of the tumor was 22 mm (range, 8 to 39). Resection had been performed previously in 42 patients (26 percent); in 13 patients the tumor represented a recurrence of disease after a previous total resection. Facial function was normal in 76 percent of the patients before radiosurgery, and 20 percent had useful hearing.

RESULTS

The rate of tumor control (with no resection required) was 98 percent. One hundred tumors (62 percent) became smaller, 53 (33 percent) remained unchanged in size, and 9 (6 percent) became slightly larger. Resection was performed in four patients (2 percent) within four years after radiosurgery. Normal facial function was preserved in 79 percent of the patients after five years (House-Brackmann grade 1), and normal trigeminal function was preserved in 73 percent. Fifty-one percent of the patients had no change in hearing ability. No new neurologic deficits appeared more than 28 months after radiosurgery. An outcomes questionnaire was returned by 115 patients (77 percent of the 149 patients still living). Fifty-four of these patients (47 percent) were employed at the time of radiosurgery, and 37 (69 percent) remained so. Radiosurgery was believed to have been successful by all 30 patients who had undergone surgery previously and by 81 (95 percent) of the 85 who had not. Thirty-six of the 115 patients (31 percent) described at least one complication, which resolved in 56 percent of those cases.

CONCLUSIONS

Radiosurgery can provide long-term control of acoustic neuromas while preserving neurologic function.

Death from a malignant cerebellopontine angle triton tumor despite stereotactic radiosurgery. Case report

Malignant vestibular nerve tumors are rare: to date, only three cases have been reported in the literature. The authors report a case of an eighth cranial nerve tumor that progressed 5 years after stereotactic radiosurgery. The patient was a 44-year-old man who underwent stereotactic radiosurgery for a 27-mm cerebellopontine angle tumor that was discovered on investigation of tinnitus and hearing loss. He developed facial weakness after 5 years, and repeated imaging revealed tumor enlargement. Despite complete microsurgical excision, the tumor rapidly recurred locally and subsequently disseminated within the neuraxis. The patient died 1 year after tumor progression was detected. Histopathological analysis revealed a malignant spindle cell neoplasm with frequent mitotic figures. The presence of positive rhabdoid elements on immunohistochemical studies confirmed that it was a triton tumor. The authors review the relevant literature concerning the classification and management of malignant vestibular nerve tumors and discuss the implications of tumor progression after stereotactic radiosurgery.

Black holes, white dwarfs and supernovas: imaging after radiosurgery

PURPOSE

To evaluate the imaging and pathological correlates of successful or risk-related stereotactic radiosurgery (SR). Methods and Materials. The ten-year Gamma Knife experience in 2,344 patients at the University of Pittsburgh was reviewed. In addition, the results or radiosurgery primate, rat, and mouse models were analyzed. Successful results and untoward complications were evaluated.

RESULTS

Dose, volume, location and histology affected the imaging changes seen after SR. Imaging changes range from central loss of contrast ('black holes'), shrinkage with diffuse contrast uptake ('white dwarfs'), or stabilization or growth arrest. Limited pathological data indicates that the prevention of cell division coupled with vascular obliteration results in tumor control, whereas a progressive endothelial proliferative and obliterative response results in arteriovenous malformation (AVM) obliteration. Perilesional imaging changes, especially in vascular malformations, may reflect flow phenomena, interstitial edema, or profound reactive astrocytosis ('supernovas').

CONCLUSION

Imaging changes correlate with both success and risks of stereotactic radiosurgery; however, pathological correlates are limited. High resolution neurodiagnostic imaging provides the best quality control available to assess the response to stereotactic radiosurgery. In the future, additional molecular probes are necessary to assess the radiobiological effects of radiosurgery.

Gamma knife radiosurgery as the first surgery for trigeminal neuralgia

To evaluate the role of Gamma Knife radiosurgery as the first surgical therapy in the management of medically refractory trigeminal neuralgia, we reviewed outcomes on our first 23 patients who had radiosurgery as primary surgical therapy. These patients represented 19% of our overall series. Mean patient age was 66 years, and mean follow-up after radiosurgery was 12 months (range 5-33 months). For most patients, radiosurgery was performed because the patient had medical contraindications to open surgery. 14 patients had 70-Gy radiosurgery, and 9 patients, 80 Gy. Radiosurgery was performed using a single 4 mm isocenter. Postoperative imaging 6 to 9 months following radiosurgery confirmed regions of enhancement at the radiosurgical target. Nine patients received 70 Gy, and 8 patients had 80 Gy. 17 patients (74%) had an excellent result (total pain relief). Five patients (22%) achieved a good result (50-90% improvement). One patient had a poor result (4%) after 70-Gy radiosurgery and subsequently underwent microvascular decompression. No patient developed facial numbness or any other complication after Gamma Knife radiosurgery. Gamma Knife radiosurgery using 70 or 80 Gy targeted to the proximal trigeminal nerve proved to be a safe and effective primary surgical therapy for medically refractory trigeminal neuralgia. The overall response rate (96%) was similar to that obtained with other surgical therapies performed as a first procedure.

Stereotactic radiosurgery for cerebral metastatic melanoma: factors affecting local disease control and survival

PURPOSE

The development of a brain metastasis represents an ominous event for patients with malignant melanoma. We evaluated results after stereotactic radiosurgery (SR) for patients with metastastic melanoma to identify patient outcomes and factors for survival.

METHODS

The authors reviewed the management results of 60 consecutive patients with melanoma metastases, with a total of 118 melanoma brain metastases, undergoing SR during a 9-year interval. Of these, 51 also had whole-brain radiation therapy (WBRT). A total of 118 tumors of mean volume of 2.95 ml (range, 0.1-25.5 ml) were treated by SR with a mean margin dose of 16.4 Gy (range, 10 to 20 Gy). Univariate and multivariate analyses were used to determine significant prognostic factors affecting survival in 60 patients.

RESULTS

Median survival was 7 months after SR in all 60 patients and 10 months from brain tumor diagnosis (mean follow-up period, 9.3 months). Lack of active systemic disease and a solitary metastasis were associated with improved survival in multivariate analysis (median, 15 months). The imaging-defined local control rate of evaluable tumors (n = 72) was 90% (disappearance = 11%, shrinkage = 44%, and stable = 35%). Local recurrence developed in 7 patients and remote brain disease developed in 14 patients. WBRT combined with radiosurgery did not improve survival nor local tumor control. New brain metastases developed less often when WBRT was added to SR (23% vs. 44%), but this difference was not significant. Only 4 patients (7%) died from progression of a radiosurgery-managed tumor. No patient developed a delayed radiation-related complication, but 3 patients developed delayed intratumoral hemorrhage at the radiosurgery site, 2 of whom had new symptoms.

CONCLUSIONS

Stereotactic radiosurgery for melanoma brain metastasis is effective and is associated with few complications. The use of radiosurgery alone is an appropriate management strategy for many patients with solitary tumors.

Outcomes after gamma knife radiosurgery in solitary acoustic tumors and neurofibromatosis Type 2

Surgeons perform stereotactic radiosurgery as the main alternative to acoustic tumor (vestibular schwannoma) resection. The goals of radiosurgery include preservation of neurological function and prevention of tumor growth. Longer-term outcomes are not well documented for patients with solitary tumors or those with neurofibromatosis Type 2 (NF2).

To define outcomes, the authors evaluated 462 consecutive patients with solitary acoustic tumors and 40 patients with NF2 (total of 45 tumors treated) who underwent radiosurgery between 1987 and 1998.

Serial imaging studies, clinical evaluations, and a patient survey were performed. The average tumor margin dose was 15 Gy, and the mean transverse tumor diameter was 22 mm. In patients with solitary tumors, prior resection had been performed in 111 patients (24%); 27 patients experienced tumor recurrence after a “total resection.”

The clinical tumor control rate (no resection required) was 98%. In non-NF2 patients followed for at least 5 years, 100 tumors (61.7%) were smaller, 53 (32.7%) remained unchanged in size, and nine (5.6%) were slightly larger. Resection was performed in four patients (2.4%). Neurological deficits after radiosurgery all occurred within the first 28 months. The rates of facial and trigeminal neuropathy varied with radiosurgery technique. In patients with NF2, 16 tumors were smaller, 28 remained unchanged, and one enlarged (overall 98% control rate at median 3-year follow up). Resection was performed in three patients (7%). Useful hearing was preserved in six (43%) of 14 NF2 patients who had useful hearing before radiosurgery.

Radiosurgery provided long-term tumor control associated with high rates of neurological function preservation. No further tumor surgery was necessary in 98% of patients with solitary tumors followed for a minimum of 5 years.

Vestibular schwannoma management in the next century: a radiosurgical perspective

PURPOSE

To discuss how the evolution of vestibular schwannoma radiosurgery, changes in health care delivery, and patient accessibility to medical information will affect the management of vestibular schwannomas in the future.

CONCEPT

In comparison with microsurgical resection of vestibular schwannomas, radiosurgery has a lower morbidity rate, a similar risk of requiring further surgery, and higher patient satisfaction. As this information becomes more widely available to patients and third-party payors, radiosurgery may replace surgical resection as the preferred management strategy for patients with small to medium sized vestibular schwannomas in the United States.

RATIONALE

It is estimated that 2500 patients are diagnosed with vestibular schwannomas each year in the United States. Assuming that 80% undergo surgery, 2000 operations are performed annually for newly diagnosed vestibular schwannomas. Data available since 1987 regarding the number of cases for which gamma knife radiosurgery was performed were used to predict the number of patients who will undergo vestibular schwannoma radiosurgery in the future. If the current trend continues, an equal number of patients will undergo surgical resection and radiosurgery to treat their vestibular schwannomas (approximately 1000/yr) sometime between 2005 and 2010. Moreover, it is predicted that by 2020, two-thirds of the patients who are newly diagnosed with vestibular schwannomas will undergo radiosurgery, with surgical resection being reserved for patients with large tumors associated with symptomatic brain stem compression.

DISCUSSION

Early data regarding vestibular schwannoma radiosurgery predicted an exponential growth curve. Although it is premature to assume that the current trend will continue, it is likely that an ever increasing percentage of patients will undergo radiosurgery as accessibility to this alternative increases, and more data are published regarding long-term tumor growth control rates. If the mathematical model proves to be accurate, then stereotactic radiosurgery will replace surgical resection as the preferred management strategy for the majority of patients with vestibular schwannomas.

Stereotactic radiosurgery for tentorial meningiomas

Radical microsurgical resection is the procedure of choice for tentorial meningiomas. Despite advances in microsurgery, tentorial meningiomas continue to challenge surgeons and patients. To evaluate the response of tentorial meningiomas, we evaluated 41 patients who had Gamma knife stereotactic radiosurgery during a 9 year period. Patient age varied from 32 to 79 years. Headache, trigeminal neuralgia, or facial paraesthesia were the most common presenting symptoms. Sensory deficits in the distribution of the trigeminal nerve were the most common finding. Eighteen patients (44%) had undergone between 1 and 5 (mean, 1.9) resections prior to radiosurgery; 23 had tumors diagnosed by neuroimaging. The average tumor diameter in this series was 20 mm. The maximum tumor dose varied from 24 to 40 Gy (mean, 30.5 Gy), and the tumor margin dose varied from 12 to 20 Gy (mean, 15.3 Gy). During the average follow-up interval of 3 years (range, 1-8 years), 19 patients had clinical improvement, 20 remained stable, and 2 patients deteriorated. Follow-up imaging showed a reduction in tumor size in 18 patients, no further tumor growth in 22, and an increase in tumor size in one (overall tumor control rate of 98%). Stereotactic radiosurgery using the Gamma Knife was a safe and effective primary or adjuvant treatment for patients with tentorial meningiomas.

The prospective natural history of cerebral venous malformations

OBJECTIVE

A 10-year prospective clinical and magnetic resonance imaging study was undertaken to determine the natural history of venous malformations. We assessed the hemorrhage rate and morbidity associated with venous malformations of the brain.

PATIENTS AND METHODS

From 1986 to 1996, 80 patients with venous malformations were referred to the University of Pittsburgh multidisciplinary vascular malformation study group for evaluation. Observation was recommended for all patients. Follow-up clinical information was obtained from patients or their referring physicians through questionnaire or phone conversation.

RESULTS

Twenty-two patients presented with neurological signs or symptoms that were thought to be related to the malformations (nine with headaches, four with seizures, three with sensory symptoms, three with motor deficits, two with trigeminal neuralgia, and one with an extrapyramidal disorder). Twenty-three patients presented with headaches that were not considered to be related to the malformations. The retrospective hemorrhage rate (from birth to study entry) was 0.61% (18 bleeds in 2,949 patient-years). Sixteen patients had sustained previous brain hemorrhage in the region of the venous malformations, two of whom had suffered subsequent hemorrhage. During the prospective follow-up period totaling 298 patient-years of clinical observation, two patients suffered hemorrhage (0.68% per year), but only one had a symptomatic bleed (0.34% per year). This patient had not hemorrhaged previously. One of these patients remained asymptomatic, whereas the second developed temporary worsening of facial paresthesias. No patient died as a result of the venous malformations.

CONCLUSION

The hemorrhage rate of a patient with venous malformations is similar to the rates presented in previous reports for patients with cavernous malformations without previous symptomatic hemorrhage. We think that hemorrhage in a patient with venous malformations may be related to an underlying but not yet documented cavernous malformation. Because of the low risk for new neurological events, we advocate conservative management. The risks associated with surgical intervention greatly exceed the low risk of morbidity related to venous malformation hemorrhage.

Stereotactic radiosurgery for brain metastasis from renal cell carcinoma

BACKGROUND

The authors evaluated results after stereotactic radiosurgery (SR) for brain metastases from renal cell carcinoma (RCC) and identified factors associated with improved survival and tumor control.

METHODS

The authors reviewed the management results from a total of 52 RCC brain metastases in 35 consecutive patients who underwent stereotactic radiosurgery (SR) during a 9-year interval. Twenty-eight patients also underwent whole brain radiation therapy (WBRT). The mean tumor volume was 2.4 mL (range, 0.1-14.1 mL). The mean dose delivered to the tumor margin was 17 gray (Gy) (range, 13-20 Gy). Univariate and multivariate testing was performed to determine significant prognostic factors.

RESULTS

The median survival was 11 months after SR and 14 months after brain tumor diagnosis. Only 2 patients (8%) died of progression of the irradiated tumor. Age < 55 years, lack of active systemic disease, and use of chemotherapy and/or immunotherapy after SR were significant favorable prognostic factors in multivariate testing. Post-SR imaging was evaluated in 26 patients (39 tumors). The local control rate from the 39 treated tumors imaged was 90% (tumor disappearance, 21%; tumor regression, 44%; and stable disease, 26%). Local recurrence developed in 3 patients (4 lesions) and remote brain disease in 12 patients. No patient developed a new focal neurologic deficit due to SR. Patients were classified into two groups: SR with and SR without WBRT. The addition of WBRT to SR did not improve survival. Distant failure occurred similarly in both groups (46% vs. 50%). WBRT combined with SR may contribute to local control, but did not prevent the development of new remote tumors.

CONCLUSIONS

SR for brain metastasis from RCC results in brain disease control in the majority of patients and was associated with few complications. Early detection of brain metastases and treatment with SR provides extended quality survival.

Factors associated with successful arteriovenous malformation radiosurgery

OBJECTIVE

To analyze the clinical and angiographic variables that affect the results of arteriovenous malformation (AVM) radiosurgery and to propose a new method of reporting patient outcomes after AVM radiosurgery. This method incorporates both the obliteration status of the AVMs and the postoperative neurological condition of the patient.

METHODS

Patient outcomes were defined as excellent (nidus obliteration and no new deficits), good (nidus obliteration with a new minor deficit), fair (nidus obliteration with a new major deficit), unchanged (incomplete nidus obliteration without a new deficit), poor (incomplete nidus obliteration with any new deficit), and dead. Two hundred twenty patients who underwent AVM radiosurgery at our center before 1992 were subjected to a multivariate analysis with patient outcomes as the dependent variable.

RESULTS

Multivariate analysis determined four factors associated with successful AVM radiosurgery: smaller AVM volume (P=0.003), number of draining veins (P=0.001), younger patient age (P=0.0003), and hemispheric AVM location (P=0.002). Preradiosurgical embolization was a negative predictor of successful AVM radiosurgery (P=0.02).

CONCLUSION

AVM obliteration without new neurological deficits can be achieved in at least 80% of patients with small volume, hemispheric AVMs after single-session AVM radiosurgery. Future studies on AVM radiosurgery should report patient outcomes in a fashion that incorporates all the factors involved in successful AVM radiosurgery.

Radiosurgical management of intracranial vascular malformations

Stereotactic radiosurgery is an important treatment option for arteriovenous malformations (AVMs) and hemorrhagic cavernous malformations. Radiosurgery is effective in obliterating AVMs and preventing rebleeding of cavernous malformations with two or more hemorrhagic episodes. Outcome analyses of radiosurgery for these vascular malformations have provided important information to improve the safety and effectiveness of radiosurgical treatment.

Stereotactic radiosurgery for chordoma and chondrosarcoma: further experiences

PURPOSE

Skull base chordomas and chondrosarcomas pose management challenges owing to their critical location, locally aggressive nature, and high recurrence rate despite multimodality treatment. We used stereotactic radiosurgery as primary or adjuvant therapy to achieve safe and effective therapeutic irradiation.

METHODS AND MATERIALS

At an average of 4 years (range 1-7), we evaluated 15 patients (nine with chordomas and six with chondrosarcomas) who had gamma-knife radiosurgery as an adjunct (13 patients) or as an alternative to microsurgical resection (two patients). Patient age varied from 7 to 70 years (mean 38). There was a distinct male preponderance (2:1). Thirteen patients had undergone between one and four resections. Using conformal radiosurgical planning, a maximum tumor dose of 24-40 Gy (mean 36) and a tumor margin dose of 12-20 Gy (mean 18) was given to a mean tumor volume of 4.6 ml.

RESULTS

Eight patients showed clinical improvement, three remained stable, and four died. Two of the four patients who died had tumor progression remote from the radiosurgery volume; two patients died of unrelated disorders. Among 11 surviving patients, follow-up imaging showed a reduction in tumor size in five, no further tumor growth in five, and an increase in the size of the tumor in one. The patient with further tumor growth after radiosurgery subsequently underwent repeat resection.

CONCLUSION

Despite the formidable management challenge posed by these neoplasms, our long-term evaluation has shown that radiosurgery is a safe and effective treatment for patients with small volume tumors.

Ablative surgery for movement disorders. Anatomic localization techniques

The increased use of ablative movement disorder surgery, pallidotomy, and thalamotomy must be followed by our better understanding of regional neuroanatomy, use of imaging and physiologic techniques for targeting, and methods of lesion creation. The safety of these techniques has been established; efficacy will require additional studies. Selection of appropriate patients and our understanding of outcomes will assist the surgeon in choosing between ablative surgeries and other forms of management.

The origin and evolution of the University of Pittsburgh Department of Neurological Surgery

Neurological surgery at the University of Pittsburgh began more than 60 years ago with the arrival of Stuart Niles Rowe. During the years, the department has been led by four men, each of whom guided the department into the future in his unique way. These men and many other dedicated physicians, nurses, and staff members have contributed to this organization and created an environment where neurosurgery flourishes. This article describes the development of neurosurgery within the "Steel City" and outlines the origin and growth of the Department of Neurological Surgery at The University of Pittsburgh Medical Center.

Management of petroclival meningiomas by stereotactic radiosurgery

OBJECTIVE

To evaluate the role of stereotactic radiosurgery in the management of petroclival meningiomas, we retrospectively reviewed our experience with 62 patients managed at the University of Pittsburgh during an 8-year period.

METHODS

All patients had cranial base meningiomas involving the region between the petrous apex and the upper two-thirds of the clivus. Some tumors extended into the cavernous sinus. Each of 39 patients (63%) had previously undergone one or more attempts at surgical resection. Seven patients (11%) had received fractionated external beam radiation therapy. Using the gamma knife, conformal multiple isocenter radiosurgery was performed with tumor margin doses of 11 to 20 Gy.

RESULTS

During the median follow-up period of 37 months, neurological statuses improved in 13 patients (21%), remained stable in 41 patients (66%), and eventually worsened in 8 patients (13%). Tumor volumes decreased in 14 patients (23%), remained stable in 42 patients (68%), and increased in 5 patients (8%). Despite the proximity of these tumors to critical neural and vascular structures, complications resulting from radiosurgery were rare. Five patients (8%) developed new cranial nerve deficits within 24 months of radiosurgery, although none had evidence of tumor progression. These deficits resolved completely in two patients within 6 months of onset.

CONCLUSION

Although an even longer follow-up period is desirable, we conclude that stereotactic radiosurgery provides a safe and effective management strategy for petroclival meningiomas, both as a primary procedure and as an adjunct to incomplete resection.