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Keisuke Maruyama, Douglas Kondziolka, Ajay Niranjan, John C. Flickinger, and L. Dade Lunsford

Object. Management options for arteriovenous malformations (AVMs) of the brainstem are limited. The long-term results of stereotactic radiosurgery for these disease entities are poorly understood. In this report the authors reviewed both neurological and radiological outcomes following stereotactic radiosurgery for brainstem AVMs over 15 years of experience.

Methods. Fifty patients with brainstem AVMs underwent gamma knife surgery between 1987 and 2002. There were 29 male and 21 female patients with an age range of 7 to 79 years (median 35 years). Anatomical locations of these AVMs included the midbrain (39 lesions), pons (20 lesions), and medulla oblongata (three lesions). The radiation dose applied to the margin of the AVM varied from 12 to 26 Gy (median 20 Gy). Forty-five patients were followed up from 5 to 176 months (mean 72 months). The angiographically confirmed actuarial obliteration rate was 66% at the final follow-up examination. Two patients experienced a hemorrhage before obliteration. The annual hemorrhage rate was 1.7% for the first 3 years after radiosurgery and 0% thereafter. Patients who had received irradiation at two or fewer isocenters had higher obliteration rates (80% compared with 44% for > two isocenters, p = 0.006), and this was related to a more spherical nidus shape. The rate of persistent neurological complications in patients treated using magnetic resonance imaging—based dose planning after 1993 was 7%, compared with 20% in patients treated before 1993. An older patient age, a lesion located in the tectum, and a higher radiosurgery-based score were significantly associated with greater neurological complications.

Conclusions. Stereotactic radiosurgery provided complete obliteration of AVMs in two thirds of the patients with a low risk of latency-interval hemorrhage. Better three-dimensional imaging studies and conformal dose planning reduced the risk of adverse radiation effects. Younger patients harboring more spherical AVMs that did not involve the tectal plate had the best outcomes.

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David W. Roberts

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Douglas Kondziolka, L. Dade Lunsford, Jay S. Loeffler, and William A. Friedman

Object. Radiosurgery and radiation therapy represent important but unique treatment paradigms for patients with certain neoplasms, vascular lesions, or functional disorders. The authors discuss their differences.

Methods. Reviewing the authors' experiences shows how the roles of these approaches vary just as their techniques differ. The distinct differences include the method of target localization (intraoperative compared with pretreatment) and irradiation (focused compared with wide-field), their radiobiology (effects of a single high-dose compared with multiple fractions), the physicians and other health personnel involved in the conduct of these procedures (surgical team compared with radiation team), and the expectations that follow treatment. During the last decade, considerable confusion has grown regarding nomenclature, requisite physician training, and the roles of the physician and surgeon. Ten years ago, two task forces on radiosurgery were created by national organizations in neurosurgery and radiation oncology to address these issues of procedural conduct and quality-assurance requirements. At the present time these guidelines are widely ignored. Currently, many patients, payers, and regulatory agencies are bewildered. What are the differences among stereotactic radiosurgery, fractionated radiation therapy, and stereotactic radiation therapy? Radiosurgery is to radiation therapy as microsurgery is to “microtherapy.”

Conclusions. In this report the authors discuss terminology, training, and physician roles in this expanding field.

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Jason Sheehan, Douglas Kondziolka, John Flickinger, and L. Dade Lunsford

Object. Glomus jugulare tumors are rare tumors that commonly involve the middle ear, temporal bone, and lower cranial nerves. Resection, embolization, and radiation therapy have been the mainstays of treatment. Despite these therapies, tumor control can be difficult to achieve particularly without undo risk of patient morbidity or mortality. The authors examine the safety and efficacy of gamma knife surgery (GKS) for glomus jugulare tumors.

Methods. A retrospective review was undertaken of the results obtained in eight patients who underwent GKS for recurrent, residual, or unresectable glomus jugulare tumors. The median radiosurgical dose to the tumor margin was 15 Gy (range 12–18 Gy). The median clinical follow-up period was 28 months, and the median period for radiological follow up was 32 months.

All eight patients demonstrated neurological stability or improvement. No cranial nerve palsies arose or deteriorated after GKS. In the seven patients in whom radiographic follow up was obtained, the tumor size decreased in four and remained stable in three.

Conclusions. Gamma knife surgery would seem to afford effective local tumor control and preserves neurological function in patients with glomus jugulare tumors. If long-term results with GKS are equally efficacious, the role of stereotactic radiosurgery will expand.

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Jason Sheehan, Douglas Kondziolka, John Flickinger, and L. Dade Lunsford

Object. Lung carcinoma is the leading cause of death from cancer. More than 50% of those with small cell lung cancer develop a brain metastasis. Corticosteroid agents, radiotherapy, and resection have been the mainstays of treatment. Nonetheless, median survival for patients with small cell lung carcinoma metastasis is approximately 4 to 5 months after cranial irradiation. In this study the authors examine the efficacy of gamma knife surgery for treating recurrent small cell lung carcinoma metastases to the brain following tumor growth in patients who have previously undergone radiation therapy, and they evaluate factors affecting survival.

Methods. A retrospective review of 27 patients (47 recurrent small cell lung cancer brain metastases) undergoing radiosurgery was performed. Clinical and radiographic data obtained during a 14-year treatment period were collected. Multivariate analysis was utilized to determine significant prognostic factors influencing survival.

The overall median survival was 18 months after the diagnosis of brain metastases. In multivariate analysis, factors significantly affecting survival included: 1) tumor volume (p = 0.0042); 2) preoperative Karnofsky Performance Scale score (p = 0.0035); and 3) time between initial lung cancer diagnosis and development of brain metastasis (p = 0.0127). Postradiosurgical imaging of the brain metastases revealed that 62% decreased, 19% remained stable, and 19% eventually increased in size. One patient later underwent a craniotomy and tumor resection for a tumor refractory to radiosurgery and radiation therapy. In three patients new brain metastases were demonstrating on follow-up imaging.

Conclusions. Stereotactic radiosurgery for recurrent small cell lung carcinoma metastases provided effective local tumor control in the majority of patients. Early detection of brain metastases, aggressive treatment of systemic disease, and a therapeutic strategy including radiosurgery can extend survival.

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L. Dade Lunsford, Ajay Niranjan, John C. Flickinger, Ann Maitz, and Douglas Kondziolka

Object. Management options for vestibular schwannomas (VSs) have greatly expanded since the introduction of stereotactic radiosurgery. Optimal outcomes reflect long-term tumor control, preservation of cranial nerve function, and retention of quality of life. The authors review their 15-year experience.

Methods. Between 1987 and 2002, some 829 patients with VSs underwent gamma knife surgery (GKS). Dose selection, imaging, and dose planning techniques evolved between 1987 and 1992 but thereafter remained stable for 10 years. The average tumor volume was 2.5 cm3. The median margin dose to the tumor was 13 Gy (range 10–20 Gy).

No patient sustained significant perioperative morbidity. The average duration of hospital stay was less than 1 day. Unchanged hearing preservation was possible in 50 to 77% of patients (up to 90% in those with intracanalicular tumors). Facial neuropathy risks were reduced to less than 1%. Trigeminal symptoms were detected in less than 3% of patients whose tumors reached the level of the trigeminal nerve. Tumor control rates at 10 years were 97% (no additional treatment needed).

Conclusions. Superior imaging, multiple isocenter volumetric conformal dose planning, and optimal precision and dose delivery contributed to the long-term success of GKS, including in those patients in whom initial microsurgery had failed. Gamma knife surgery provides a low risk, minimally invasive treatment option for patients with newly diagnosed or residual VS. Cranial nerve preservation and quality of life maintenance are possible in long-term follow up.

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Jason P. Sheehan, Ajay Niranjan, Jonas M. Sheehan, John A. Jane Jr., Edward R. Laws, Douglas Kondziolka, John Flickinger, Alex M. Landolt, Jay S. Loeffler, and L. Dade Lunsford

Object. Pituitary adenomas are very common neoplasms, constituting between 10 and 20% of all primary brain tumors. Historically, the treatment armamentarium for pituitary adenomas has included medical management, microsurgery, and fractionated radiotherapy. More recently, radiosurgery has emerged as a viable treatment option. The goal of this research was to define more fully the efficacy, safety, and role of radiosurgery in the treatment of pituitary adenomas.

Methods. Medical literature databases were searched for articles pertaining to pituitary adenomas and stereotactic radiosurgery. Each study was examined to determine the number of patients, radiosurgical parameters (for example, maximal dose and tumor margin dose), duration of follow-up review, tumor growth control rate, complications, and rate of hormone normalization in the case of functioning adenomas.

A total of 35 peer-reviewed studies involving 1621 patients were examined. Radiosurgery resulted in the control of tumor size in approximately 90% of treated patients. The reported rates of hormone normalization for functioning adenomas varied substantially. This was due in part to widespread differences in endocrinological criteria used for the postradiosurgical assessment. The risks of hypopituitarism, radiation-induced neoplasia, and cerebral vasculopathy associated with radiosurgery appeared lower than those for fractionated radiation therapy. Nevertheless, further observation will be required to understand the true probabilities. The incidence of other serious complications following radiosurgery was quite low.

Conclusions. Although microsurgery remains the primary treatment modality in most cases, stereotactic radiosurgery offers both safe and effective treatment for recurrent or residual pituitary adenomas. In rare instances, radiosurgery may be the best initial treatment for patients with pituitary adenomas. Further refinements in the radiosurgical technique will likely lead to improved outcomes.

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Douglas Kondziolka and L. Dade Lunsford

Object

In the management of trigeminal neuralgia (TN), physicians seek rapid and long-lasting pain relief, together with preservation of trigeminal nerve function. Percutaneous retrogasserian glycerol rhizotomy (PRGR) offers distinct advantages over other available procedures. The aim of this report was to provide details of the PRGR procedure and its expected outcome.

Methods

The authors reviewed their experience with PRGR in 1174 patients to evaluate the procedural technique, results, and complications. Although it is clear that TN is not a static disorder but one characterized by remissions and recurrences, long-lasting pain relief was noted in 77% of patients, with 55% discontinuing all medications and 22% requiring some drug usage.

Conclusions

The authors discuss the role of PRGR in their practice, along with other procedures such as microvascular decompression and gamma knife surgery, for idiopathic or multiple sclerosis–related TN. They conclude that PRGR had distinct advantages over other procedures, which include eliminating the need for intraoperative confirmatory sensory testing, and a lower risk of facial sensory loss.

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Roy A. E. Bakay