Stereotactic radiosurgery versus stereotactic radiotherapy for patients with vestibular schwannoma: a Leksell Gamma Knife Society 2000 debate

Treatment of malignant tumors of the skull base with multi-session radiosurgery

OBJECTIVE

Malignant tumors that involve the skull base pose significant challenges to the clinician because of the proximity of critical neurovascular structures and limited effectiveness of surgical resection without major morbidity. The purpose of this study was to evaluate the efficacy and safety of multi-session radiosurgery in patients with malignancies of the skull base.

METHODS

Clinical and radiographic data for 37 patients treated with image-guided, multi-session radiosurgery between January 2002 and December 2007 were reviewed retrospectively. Lesions were classified according to involvement with the bones of the base of the skull and proximity to the cranial nerves.

RESULTS

Our cohort consisted of 37 patients. Six patients with follow-up periods less than four weeks were eliminated from statistical consideration, thus leaving the data from 31 patients to be analyzed. The median follow-up was 37 weeks. Ten patients (32%) were alive at the end of the follow-up period. At last follow-up, or the time of death from systemic disease, tumor regression or stable local disease was observed in 23 lesions, representing an overall tumor control rate of 74%. For the remainder of lesions, the median time to progression was 24 weeks. The median progression-free survival was 230 weeks. The median overall survival was 39 weeks. In the absence of tumor progression, there were no cranial nerve, brainstem or vascular complications referable specifically to CyberKnife radiosurgery.

CONCLUSION

Our experience suggests that multi-session radiosurgery for the treatment of malignant skull base tumors is comparable to other radiosurgical techniques in progression-free survival, local tumor control, and adverse effects.

Stereotactic Radiosurgery with the CyberKnife for Pituitary Adenomas

OBJECTIVE

In recent years, CyberKnife has emerged as an important treatment modality in the management of pituitary adenomas. Treatment results after performing CyberKnife and the complications of this procedure are reviewed.

METHODS

Twenty-six patients with pituitary adenomas received stereotactic radiosurgery with the CyberKnife (CKRS). The follow-up periods ranged from 7 months to 47 months (mean+/-SD : 30+/-12.7 months). The patients consisted of 17 with non-functioning adenomas, 3 with prolactinomas and 6 with acromegaly. The change in the tumor volume, visual acuity, hormonal function, and complications by this therapy were analyzed in each case.

RESULTS

The tumor control rate was 92.3%. Hormonal function was improved in all of the 9 (100%) functioning adenomas. Hormonal normalization was observed in 4 of the 9 (44%) patients with a mean duration of 16 months. In two patients (7.6%), visual acuity worsened due to cystic enlargement of the tumor after CKRS. No other complications were observed.

CONCLUSION

CyberKnife is considered safe and effective in selected patients with pituitary adenomas. However, longer follow-up is required for a more complete assessment of late toxicity and treatment efficacy.

MASEP gamma knife radiosurgery for secretory pituitary adenomas: experience in 347 consecutive cases

Background

Secretory pituitary adenomas are very common brain tumors. Historically, the treatment armamentarium for secretory pituitary adenomas included neurosurgery, medical management, and fractionated radiotherapy. In recent years, MASEP gamma knife radiosurgery (MASEP GKRS) has emerged as an important treatment modality in the management of secretory pituitary adenomas. The goal of this research is to define accurately the efficacy, safety, complications, and role of MASEP GKRS for treatment of secretory pituitary adenomas.

Methods

Between 1997 and 2007 a total of 347 patients with secretory pituitary adenomas treated with MASEP GKRS and with at least 60 months of follow-up data were identified. In 47 of these patients some form of prior treatment such as transsphenoidal resection, or craniotomy and resection had been conducted. The others were deemed ineligible for microsurgery because of body health or private choice, and MASEP GKRS served as the primary treatment modality. Endocrinological, ophthalmological, and neuroradiological responses were evaluated.

Results

MASEP GKRS was tolerated well in these patients under the follow-up period ranged from 60 to 90 months; acute radioreaction was rare and 17 patients had transient headaches with no clinical significance. Late radioreaction was noted in 1 patient and consisted of consistent headache. Of the 68 patients with adrenocorticotropic hormone-secreting(ACTH) adenomas, 89.7% showed tumor volume decrease or remain unchanged and 27.9% experienced normalization of hormone level. Of the 176 patients with prolactinomas, 23.3% had normalization of hormone level and 90.3% showed tumor volume decrease or remain unchanged. Of the 103 patients with growth hormone-secreting(GH) adenomas, 95.1% experienced tumor volume decrease or remain unchanged and 36.9% showed normalization of hormone level.

Conclusion

MASEP GKRS is safe and effective in treating secretory pituitary adenomas. None of the patients in our study experienced injury to the optic apparatus or had other neuropathies related with gamma knife. MASEP GKRS may serve as a primary treatment method in some or as a salvage treatment in the others. However, treatment must be tailored to meet the patient's symptoms, tumor location, tumor morphometry, and overall health. Longer follow-up is required for a more complete assessment of late radioreaction and treatment efficacy.

Initial results of fractionated CyberKnife radiosurgery for uveal melanoma

OBJECTIVE

To evaluate prospectively local tumor control and morbidity after fractionated CyberKnife radiosurgery for uveal melanoma unsuitable for ruthenium-106 brachytherapy or local resection.

METHODS

This study includes melanoma > or =7 mm in initial height, or juxtapapillary and/or juxtamacular tumors (height > or =3 mm; posterior tumor margin extending to within 3 mm of optic disk rim and/or fovea). Patients were excluded if they presented evidence of echographic extrascleral tumor extension, neovascular glaucoma, or any form of pretreatment or metastases at baseline. The eye was stabilized by the same ophthalmologist via peribulbar injection of 5 cc 2% lidocaine. CyberKnife radiosurgery was performed delivering a total dose of 60 Gy to the 80% or 85% isodose line in three fractions. The planning target volume (PTV) included the contrast-enhancing lesion on MRI plus a 1-mm margin (no margin on fovea site).

RESULTS

Five patients with uveal melanoma were treated by this procedure. All patients had serous retinal detachment associated with the tumor. No grade > or =2 acute toxicities were observed. Eight-month follow-up revealed a decrease in tumor thickness in three patients and reattachment of the retina in four. The tumors remained stable in two eyes and an increase in retinal detachment was noted in one eye. Vision improved minimally in two eyes and remained stable in three.

CONCLUSION

CyberKnife fractionated radiosurgery seems to be a viable alternative local treatment modality in uveal melanoma with no serious acute side effects. Further follow-up is indicated.

Radiotherapy of nonfunctioning and gonadotroph adenomas

Transsphenoidal surgery is the treatment of choice for NFPA but is seldom curative. The management of patients in whom residual tumor is detected after surgery is not clear-cut. Radiation therapy is effective in controlling tumor mass in the majority of patients, but is associated with long term complications that call for restriction of its use to patients at high risk for tumor growth. New radiation techniques may prove to be safer while retaining the effectiveness of conventional radiotherapy, however longer follow-up is necessary to confirm this assumption. For now, it appears to be safe to withhold radiation and carefully follow patients with small tumor remnants, whereas large remnants from invasive tumors should be considered for radiotherapy. Nevertheless, there are no prospective controlled studies that support this empirical approach.

Gamma knife radiosurgery for ten or more brain metastases

OBJECTIVE

This study was performed to assess the efficacy of GKS in patients with ten or more brain metastases.

METHODS

From Aug 2002 to Dec 2007, twenty-six patients (13 men and 13 women) with ten or more cerebral metastatic lesions underwent GKS. The mean age was 55 years (32-80). All patients had Karnofsky performance status (KPS) score of 70 or better. According to recursive partitioning analysis (RPA) classification, 3 patients belonged to class I and 23 to class II. The location of primary tumor was lung (21), breast (3) and unknown (2). The mean number of the lesions per patient was 16.6 (10-37). The mean cumulated volume was 10.9 cc (1.0-42.2). The median marginal dose was 15 Gy (9-23). Overall survival and the prognostic factors for the survival were retrospectively analyzed by using Kaplan Meier method and univariate analysis.

RESULTS

Overall median survival from GKS was 34 weeks (8-199). Local control was possible for 79.5% of the lesions and control of all the lesions was possible in at least 14 patients (53.8%) until 6 months after GKS. New lesions appeared in 7 (26.9%) patients during the same period. At the last follow-up, 18 patients died; 6 (33.3%) from systemic causes, 10 (55.6%) from neurological causes, and 2 (11.1%) from unknown causes. Synchronous onset in non-small cell lung cancer (p=0.007), high KPS score (>/=80, p=0.029), and controlled primary disease (p=0.020) were favorable prognostic factors in univariate analysis.

CONCLUSION

In carefully selected patients, GKS may be a treatment option for ten or more brain metastases.

Embolization of residual fistula following stereotactic radiosurgery in cerebral arteriovenous malformations

Treatment of brain arteriovenous malformations (BAVMs) often requires a multitechnique approach. We present 2 cases of BAVM, in which initial stereotactic radiosurgery (SRS) was successful in obliterating a significant volume of the nidus. At follow-up angiography, residual fistulas were identified and selectively embolized; this procedure cured the lesions. Many series describe initial embolization to reduce the nidal volume followed by SRS to the remnant. The described cases highlight the value of primary radiosurgery followed by selective fistula embolization.

Prediction of volumetric change in the "triple ring" caused by glioma I-125 brachytherapy

The aim of this study was to reveal the volumetric changes in tumor necrosis, reactive zone, and edema referred to as the "triple ring" appearing after low-dose-rate iodine-125 (I-125) interstitial irradiation of 20 inoperable low-grade gliomas. To enable prediction of these volumetric changes, we provide mathematical expressions that describe the dynamics of the triple ring. Volumes of the three regions on image-fused control CT/MR images were measured for a 24-month period. The delivered dose on the tumor surface was 50-60 Gy. Dose planning and image fusion were performed with Brain-Lab Target 1.19 software; mathematical and statistical computations were carried out with Matlab numeric computation and visualization software. To determine the volumes, control images with the triple rings were fused with the planning images. Relative volumes normalized with respect to the volume of reference dose were calculated and plotted in the time domain. First, the mean values of volumes were determined from the patients' measured data; then, polynomials were fitted to the mean values using the polynomial curve-fitting method. The accuracy of our results was verified by correlating the predicted data with the measured ones. The polynomial prediction approach proposed here reveals the dynamics of the triple ring. These polynomials will assist with (1) designing the best treatment, (2) following the patient's condition, and (3) planning reirradiation if necessary.

Unified dosimetry index (UDI): a figure of merit for ranking treatment plans

We have formulated a unified dosimetry index (UDI) that computes, for any given treatment plan, its deviations in terms of dose coverage, conformity, homogeneity, and dose gradient vis‐à‐vis an ideal plan (which we define as a dosimetry plan of perfect dose coverage, conformity, homogeneity, and step‐wise fall‐off to zero dose outside the planning target volume). In order to validate the UDI scoring system, 21 stereotactic cranial radiosurgery cases were evaluated retrospectively. The cases were planned on the BrainSCAN treatment planning system (BrainLAB, Feldkirchen, Germany) using 6 to 8 non‐coplanar static beams collimated with the micro multi‐leaf collimator (mMLC). We suggest a technique for creating a ranking system that can be utilized for plan evaluation and comparison between multiple plans. Under this system treatment plans are classified as “excellent”, “good”, “average”, or “poor”. The proposed ranking system can be utilized as a general guide for generating an optimal dosimetry plan for external beam radiation therapy.

Tumor-volume changes after radiosurgery for vestibular schwannoma: implications for follow-up MR imaging protocol

BACKGROUND AND PURPOSE

The outcome of radiosurgery for vestibular schwannoma (VS) is assessed by posttreatment measurement of tumor size and could be influenced by the timing and quality of the assessment. This study evaluates the volumetric changes of VS after radiosurgery and proposes a radiologic follow-up program.

MATERIALS AND METHODS

Of 142 patients with VS treated with radiosurgery, we selected patients who were followed at least 3 times during a minimum of 32 months with a T1-weighted gadolinium-enhanced high-resolution 3D MR imaging examination identical to the pretreatment MR imaging. Forty-five patients were identified with a mean follow-up of 50 months (range, 32-78 months). Pre- and posttreatment tumor volumes were calculated by using BrainSCAN software by manually contouring tumors on each MR imaging study. Volume changes of >13% were defined as events.

RESULTS

At last follow-up MR imaging, volumes were smaller in 37 (82.2%) of the 45 patients. Eleven (29.7%) of these 37 tumors showed transient swelling preceding regression, with a median time to regression of 34 months (range, 20-55 months). Seven (15.6%) of the 45 tumors had volume progression compared with the tumor on pretreatment MR imaging studies. Of these 7 tumors, 3, however, had volume regression compared with the preceding MR imaging study, and in 4, volume progression was ongoing. One tumor remained the same.

CONCLUSIONS

Tumor-volume measurements by standardized T1-weighted gadolinium-enhanced high-resolution 3D MR imaging follow-up protocols revealed good local control of VS after radiosurgery. The first-follow-up MR imaging at 2 years and the second at 5 years postradiosurgery differentiated transient progression from ongoing progression and may prevent unnecessary therapeutic interventions.

The history and future of deep brain stimulation

The advancement of electrical stimulation of the central nervous system has been a story of fits and bursts with numerous setbacks. In many ways, this history has paralleled the history of medicine and physics. We have moved from anecdotal observation to double-blinded, prospective randomized trials. We have moved from faradic stimulation to systems that lie completely under the skin and can deliver complex electrical currents to discrete areas of the brain while controlled through a device that is not much bigger than a PDA. This review will discuss how deep brain stimulation has developed into its current form, where we see the field going and the potential pitfalls along the way.

[Brain metastases in cases of renal cell carcinoma]

Brain metastases represent the most common intracranial neoplasia. The lung, breast and kidney are the primary tumor locations most often associated with brain metastasis. Seizures and neurological impairment are typical manifestations of neoplastic cerebral dissemination, which, when untreated, usually lead to death within a few months. In this review, we discuss whole brain radiotherapy, surgical resection and stereotactic radiosurgery as the currently used therapeutic options for renal cell cancer metastasis in the brain.

Radiosurgery in the treatment of brain metastases: critical review regarding complications

Stereotactic radiosurgery (SRS) has been described as an effective treatment option for brain metastases. In general, SRS has been indicated for the treatment of lesions smaller than 3 cm in maximum diameter and for lesions considered not surgically treatable, owing to the patient's clinical status or because the lesion was located in or near eloquent brain areas. In several studies, SRS has been associated with clinical and radiographic improvement of the lesions and has been compared with surgery as the modality of choice for brain metastases. Beyond the high rate of local disease control with SRS, the few complications that have been described occurred mainly in the acute post treatment period. Most publications have addressed the outcome and effectiveness of this treatment modality but have not critically analyzed long-term complications, steroid dependency, or results relating to specific brain locations. It is important to understand the radiobiologic effects of a well-demarcated high dose of radiation on the brain lesion, controlling the tumor growth and not causing significant alteration of the related brain region, especially in an area controlling eloquent function.

Long-term Outcomes of Gamma Knife Stereotactic Radiosurgery of Vestibular Schwannomas

OBJECTIVE

Gamma Knife Stereotactic Radiosurgery (GK SRS) has become an important treatment modality for vestibular schwannomas. We evaluated the tumor control rate, patterns of tumor volume change and preservation of hearing following low-dose radiation for vestibular schwannomas in a homogeneous cohort group in which the mean marginal dose was 12 Gy.

METHODS

A total of 59 patients were enrolled in this study. All enrolled patients were followed-up for at least 5 years and the radiation dose was 11-13 Gy. Regular MRI, audiometry and clinical evaluations were done and tumor volumes were obtained from MRI using the OSIRIS program.

RESULTS

The tumor control rate was 97%. We were able to classify the patterns of change in tumor volume into three categories. Transient increases in tumor volume were detected in 29% of the patients and the maximum transient increase in tumor volume was identified at 6 to 30 months after GK SRS. The transient increases in tumor volume ranged from 121% to 188%. Hearing was preserved in 4 of the 12 patients who had serviceable hearing prior to treatment. There were no other complications associated with GK SRS.

CONCLUSION

Low-dose GK SRS was an effective and safe mode of treatment for vestibular schwannomas in comparison to the previously used high-dose GK SRS. Transient increases in tumor volume can be identified during the follow-up period after low-dose GK SRS for vestibular schwannomas. Physicians should be aware that these increases are not always indicative of treatment failure and that close observation is required following treatments. Unfortunately, a satisfactory hearing preservation rate was not achieved by reducing the radiation dose. It is thought that hearing preservation is a more sophisticated problem and further research is required.

Comparing size evaluation methods for acoustic neuroma after stereotactic radiosurgery

PURPOSE

Acoustic neuroma tumor size may be evaluated using several methods. Here we investigate the variations among measuring techniques.

MATERIALS AND METHODS

A retrospective analysis of pre- and posttreatment magnetic resonance (MR) scans was performed on 15 acoustic neuroma patients with a history of stereotactic radiosurgery who had been followed for more than 2 years. Tumor size was measured on each MR scan using three methods, where the extracanalicular (EX) and intracanalicular (IN) portions were measured separately. We collected data on the largest diameter (M1), the square root of the product of the maximum anteroposterior and mediolateral diameter (M2), and the average for the maximum anteroposterior, mediolateral, and superoinferior diameters (M3). Size differences between follow-up MR scans separated by more than 2 years were calculated for each method, and we evaluated whether the tumors progressed, remained stable, or regressed.

RESULTS

A total of 154 follow-up pairs of EX and 115 follow-up pairs of IN showed a statistically significant difference for the number of each category among the three methods (P = 0.03, P < 0.01, respectively). The greatest category agreement was observed between the M2 and M3 methods.

CONCLUSION

A significant difference between the tumor size measuring methods was observed. To strengthen specificity when evaluating tumor size difference, a measuring method using two or more parameters is recommended.

Exceptionally high incidence of symptomatic grade 2-5 radiation pneumonitis after stereotactic radiation therapy for lung tumors

BACKGROUND

To determine the usefulness of dose volume histogram (DVH) factors for predicting the occurrence of radiation pneumonitis (RP) after application of stereotactic radiation therapy (SRT) for lung tumors, DVH factors were measured before irradiation.

METHODS

From May 2004 to April 2006, 25 patients were treated with SRT at the University of Tokyo Hospital. Eighteen patients had primary lung cancer and seven had metastatic lung cancer. SRT was given in 6-7 fields with an isocenter dose of 48 Gy in four fractions over 5-8 days by linear accelerator.

RESULTS

Seven of the 25 patients suffered from RP of symptomatic grade 2-5 according to the NCI-CTC version 3.0. The overall incidence rate of RP grade2 or more was 29% at 18 months after completing SRT and three patients died from RP. RP occurred at significantly increased frequencies in patients with higher conformity index (CI) (p = 0.0394). Mean lung dose (MLD) showed a significant correlation with V5-V20 (irradiated lung volume) (p < 0.001) but showed no correlation with CI. RP did not statistically correlate with MLD. MLD had the strongest correlation with V5.

CONCLUSION

Even in SRT, when large volumes of lung parenchyma are irradiated to such high doses as the minimum dose within planning target volume, the incidence of lung toxicity can become high.

Radiotherapy for nonfunctioning pituitary adenomas: from conventional to modern stereotactic radiation techniques

The initial management of nonfunctioning pituitary macroadenomas (NFAs) is usually surgery; however, a significant proportion of NFAs may require further treatment. Radiotherapy is currently used in patients with residual tumour and achieves excellent long-term control, but there are concerns about potential late toxicity. Stereotactic radiotherapy, both in the form of radiosurgery or fractionated stereotactic radiotherapy, has been developed as a more accurate technique of irradiation with more precise tumour localization and consequently a reduction in the volume of normal tissue, particularly the brain, irradiated to high radiation doses. A review of the literature suggests that new radiation techniques offer safe and effective treatment for recurrent or residual pituitary adenomas; however longer follow-up is necessary to confirm the excellent tumour control and the potential reduction of long-term radiation toxicity. Currently, radiotherapy has an important role in patients with residual or progressive disease after surgery. Patients with small or no residual tumours after surgery may generally continue on a policy of surveillance without immediate irradiation, in order to avoid the potential toxicity of treatment.

Stereotactic radiosurgery for atypical and anaplastic meningiomas

Atypical and anaplastic meningiomas frequently recur in the relatively short-term after surgery. We have followed such postoperative cases by short-interval repeated MRI and have performed stereotactic radiosurgery (SRS) for progressive tumors as a salvage therapy. The objective of this report was assessment of the degree of tumor control, the risk of complications, and the presence of variables that predict outcome in patients treated with SRS for high-grade meningiomas. We reviewed 12 high-grade meningioma patients with 30 lesions treated by Linac-based SRS at Kyoto University Hospital between 1997 and 2002. They included 10 atypical meningiomas and 2 anaplastic ones according to the WHO classification. A mean tumor volume was 4.40cc and a mean marginal dose of SRS was 18.0 Gy (12-20 Gy). After a mean follow-up period of 43.4 months (6-84 months), 13 lesions had progression tumor within the SRS field and 6 lesions had out of the SRS field. Nine of 14 lesions, which were treated by SRS with a marginal dose of less than 20 Gy, had local recurrence in the SRS field. In contrast, four of 16 lesions, which were treated with marginal dose of 20 Gy, had local recurrence in the SRS field. The marginal dose <20 Gy was a statistically significant factor for a short-term progression in high-grade meningiomas (P = 0.0139). Five-year progression-free survival ratio in lesions treated with SRS below 20 Gy and 20 Gy were 29.4% and 63.1%, respectively. In conclusion, based on our findings, we suggest that recurrent high-grade meningiomas be treated by SRS with a marginal dose exceeding 20 Gy.

CyberKnife radiosurgery in the treatment of complex skull base tumors: analysis of treatment planning parameters

Background

Tumors of the skull base pose unique challenges to radiosurgical treatment because of their irregular shapes, proximity to critical structures and variable tumor volumes. In this study, we investigate whether acceptable treatment plans with excellent conformity and homogeneity can be generated for complex skull base tumors using the Cyberknife^® radiosurgical system.

Methods

At Georgetown University Hospital from March 2002 through May 2005, the CyberKnife^® was used to treat 80 patients with 82 base of skull lesions. Tumors were classified as simple or complex based on their proximity to adjacent critical structures. All planning and treatments were performed by the same radiosurgery team with the goal of minimizing dosage to adjacent critical structures and maximizing target coverage. Treatments were fractionated to allow for safer delivery of radiation to both large tumors and tumors in close proximity to critical structures.

Results

The CyberKnife^® treatment planning system was capable of generating highly conformal and homogeneous plans for complex skull base tumors. The treatment planning parameters did not significantly vary between spherical and non-spherical target volumes. The treatment parameters obtained from the plans of the complex base of skull group, including new conformity index, homogeneity index and percentage tumor coverage, were not significantly different from those of the simple group.

Conclusion

Our data indicate that CyberKnife^® treatment plans with excellent homogeneity, conformity and percent target coverage can be obtained for complex skull base tumors. Longer follow-up will be required to determine the safety and efficacy of fractionated treatment of these lesions with this radiosurgical system.

Neurovascular radiosurgery

SUMMARY

This article focuses on the treatment of neurovascular diseases, in particular brain arteriovenous malformations (BAVMs), with radiosurgery. The target group for this review is physicians who manage patients with neurovascular diseases, but are not actively engaged in radiosurgery. Radiosurgery for BAVMs is an established treatment with clearly defined risks and benefits. The efficacy of radiosurgery for dural arteriovenous shunts (DAVSs) is probably similar but the treatment has not yet gained the same acceptance. Radiosurgical treatment of cavernomas (cavernous hemangiomas) remains controversial. Well founded predictive models for BAVM radiosurgery show: * The probability of obliteration depends on the dose of radiation given to the periphery of the BAVM. * The risk of adverse radiation effects depends on the total dose of radiation, i.e. the amount of energy imparted into the tissue. The risk is greater in centrally located lesions. The risk of damage to brainstem nucleii and cranial nerves must be added to the risk predicted from current outcome models. * The risk of hemorrhage during the time span before obliteration depends on the BAVM volume, the dose of radiation to the periphery of the lesion and the age of the patient. Central location is a probably also a risk factor.

Antiepileptic therapy in patients with central nervous system malignancies

More than 200,000 patients are diagnosed with primary or metastatic brain tumors each year in the United States. Of these patients, 20% to 40% will develop seizures at presentation, and another 20% to 40% will require treatment for seizures during their illness. Although the use of antiepileptic drugs (AEDs) in patients who have had seizures seems reasonable, the issue of prophylactic AED use for patients who have not had a seizure is an intensely debated subject. The American Academy of Neurology released a position statement in May 2000 addressing the use of anticonvulsants in newly diagnosed brain tumor patients who have never had a seizure. After a review of the literature, including all trials showing class I evidence, multivariate analysis using calculated odds ratios failed to show a prophylactic benefit of preventing a first seizure versus the risk of side effects and recommended not using prophylactic anticonvulsants in newly diagnosed patients with brain tumor. Despite this recommendation, a recent survey of the American Association of Neurologic Surgeons revealed that most neurosurgeons still use anticonvulsants prophylactically in patients with brain tumor. This review mainly includes primary brain tumors, but most of the concepts are transferable to patients with metastatic tumors.

Dosimetric comparison of helical tomotherapy and Gamma Knife stereotactic radiosurgery for single brain metastasis

BACKGROUND

Helical Tomotherapy (HT) integrates linear accelerator and computerized tomography (CT) technology to deliver IMRT. Targets are localized (i.e. outlined as gross tumor volume [GTV] and planning target volume [PTV]) on the planning kVCT study while daily MVCT is used for correction of patient's set-up and assessment of inter-fraction anatomy changes. Based on dosimetric comparisons, this study aims to find dosimetric equivalency between single fraction HT and Gamma Knife stereotactic radiosurgery (GKSRS) for the treatment of single brain metastasis.

METHODS

The targeting MRI data set from the GKSRS were used for tomotherapy planning. Five patients with single brain metastasis treated with GKSRS were re-planned in the HT planning station using the same prescribed doses. There was no expansion of the GTV to create the PTV. Sub-volumes were created within the PTV and prescribed to the maximum dose seen in the GKSRS plans to imitate the hot spot normally seen in GKSRS. The PTV objective was set as a region at risk in HT planning using the same prescribed dose to the PTV periphery as seen in the corresponding GKSRS plan. The tumor volumes ranged from 437-1840 mm(3).

RESULTS

Conformality indices are inconsistent between HT and GKSRS. HT generally shows larger lower isodose line volumes, has longer treatment time than GKSRS and can treat a much larger lesion than GKSRS. Both HT and GKSRS single fraction dose-volume toxicity may be prohibitive in treating single or multiple lesions depending on the number and the sizes of the lesions.

CONCLUSION

Based on the trend for larger lower dose volumes and more constricted higher dose volumes in HT as compared to GKSRS, dosimetric equivalency was not reached between HT and GKSRS.

Prognosis of non-small cell lung cancer with synchronous brain metastases treated with gamma knife radiosurgery

The clinical outcome and prognostic factors of patients with synchronous brain metastases from non-small cell lung cancer (NSCLC) who were treated with gamma knife radiosurgery (GKS) were analyzed. A total of 35 patients with NSCLC underwent GKS as an initial treatment for metastatic brain lesions of synchronous onset. The period of survival and various prognostic factors such as age, gender, performance status, multiplicity of the brain lesions, intracranial tumor volume, and extent of the primary tumor were analyzed. The overall median survival time for this series was 12 months (range 0.75 to 43 months) from the diagnosis. Of the 21 patients who were no longer alive at the conclusion of this study, only 7 (33.3%) died of neurological causes. Multivariate analysis of these data revealed that N stage, whole-brain radiotherapy (WBRT), and chemotherapy were significant predictors for survival (p<0.05). Survival of patients with NSCLC and synchronous brain metastases is mainly dependent upon the progression of the systemic disease, provided that the cerebral lesions are treated adequately with local treatment modalities including radiosurgery. Application of radiosurgery as an initial treatment option and aggressive local and systemic modalities to control extracranial disease may improve survival.

Stereotactic radiosurgery: indications and results - part 2

Stereotactic radiosurgery and fractionated stereotactic radiotherapy represent an increasingly important option in the treatment of central nervous system disease. In this article, we discuss indications for stereotactic radiosurgery and review results reported in the medical literature.

New frontiers in radiosurgery for the brain and body

Radiosurgery is defined as the use of highly focused beams of radiation to ablate a pathologic target, thus achieving a surgical objective by noninvasive means. Recent advances have allowed a wide variety of intracranial lesions to be effectively treated with radiosurgery, and radiosurgical treatment has been accepted as a standard part of the neurosurgical armamentarium. The advent of frameless radiosurgery now permits radiosurgical treatment to all parts of the body and is being actively explored by many centers. This article reviews some of the modern tools for radiosurgical treatment and discusses the current clinical practice of radiosurgery.

Long term experience of gamma knife radiosurgery for benign skull base meningiomas

OBJECTIVES

As most reports on the gamma knife have related only to short or mid-term results, we decided to evaluate the effectiveness and toxicity of radiosurgical treatment for benign skull base meningiomas in 200 patients with a follow up of 5-12 years to define the role of gamma knife radiosurgery (GKRS) for basal meningiomas and to provide further data for comparison with other treatment options.

METHODS

In total, 99 patients were treated with a combination of microsurgical resection and GKRS. In 101 patients, GKRS was performed as the sole treatment option. Tumour volumes ranged from 0.38 to 89.8 cm3 (median 6.5 cm3), and doses of 7-25 Gy (median 12 Gy) were given to the tumour borders at covering isodose volume curves (range 20-80%, median 45%).

RESULTS

The actuarial progression free survival rate was 98.5% at 5 years and 97.2% at 10 years. Passing radiation induced oedema occurred in two patients (1%). The neurological status improved in 83 cases (41.5%), remained unaltered in 108 (54%), and deteriorated in 9 (4.5%). Worsening was transient in seven patients (3.5%) and unrelated to tumour or treatment in one (0.5%). Repeated microsurgical resection was performed in five patients following GKRS (2.5%).

CONCLUSIONS

GKRS has proved to be an effective alternative to microsurgical resection, radiotherapy, and Linac based radiosurgery for adjunctive and primary treatment of selected patients with basal meningiomas. Because of the excellent long term tumour control rate and low morbidity associated with GKRS, this treatment option should be used more frequently in the therapeutic management of benign skull base meningiomas.

Radiation therapy in the management of pediatric craniopharyngiomas--a review

Craniopharyngiomas are benign suprasellar tumors that arise from epithelial remnants of the Rathke's pouch. The two standard treatment options are primary total resection or limited surgery followed by external beam radiation. The 10- and 20-year progression-free survival rates following limited surgery and radiation therapy are superior to those achieved by primary surgery alone. The side effect profiles for these two treatment approaches are different. Following total resection there is a very high incidence of panhypopituitarism requiring lifelong multiple hormone replacement therapy. The other side effects include potential damage to adjacent structures such as optic chiasm, vasculature and hypothalamus. Following limited surgery and radiation therapy the incidence of endocrine deficits is significantly lower compared to radical surgery, as is the risk of neurovascular and hypothalamic injury. Optic neuropathy and brain necrosis are rare in modern radiation therapy series. Second malignant neoplasms, although rare, can occur. In children with recurrent craniopharyngiomas following radical surgery, the recommended salvage treatment is radiation therapy, as further surgical attempts at salvage are associated with high relapse rates and increased morbidity and mortality. There have been significant technological advances in the field of radiation treatment planning and delivery that have great potential for reducing the incidence of long-term irradiation sequelae in the developing brain. The general availability of megavoltage linear accelerators and modern radiotherapy innovations such as three-dimensional conformal radiation treatment (3D CRT), stereotactic radiosurgery (SRS), stereotactic radiotherapy (SRT), and intensity modulated radiation therapy (IMRT) should further limit the rate of complications and improve cure rates in children with primary or recurrent craniopharyngioma.

Positron emission tomography for the early postsurgical evaluation of pediatric brain tumors

OBJECT

The object was to study the value of postoperative positron emission tomography (PET) to assess the extension of brain tumor resection.

METHODS

Twenty children operated on for total resection of a glial tumor (18 low-grade, 2 anaplastic) presented a signal on postoperative magnetic resonance (MR) images raising the question of a possible tumor residue. PET was performed early ((18)F-Fluoro-deoxyglucose in 1, (11)C-methionine in 16, both in 3) to further characterize the nature of the abnormal MR signal in order to consider second-look surgery. An increased tracer uptake found in 14 children led to reoperation on 11 of them, confirming the tumor histologically. No (11)C-methionine uptake led to a conservative attitude in 6 children in whom MR imaging follow-up showed no tumor progression.

CONCLUSIONS

The early postoperative PET, especially with (11)C-methionine, appears to be a valid basis for complementary therapeutic decisions, especially second-look surgery, in glial tumors for which a radical resection is a key factor for prognosis.

Fractionated stereotactic radiotherapy for parasellar meningiomas: a preliminary report of visual outcomes

BACKGROUND/AIM

Fractionated stereotactic radiotherapy (FSRT) is a new treatment for brain tumours that are close to critical structures, such as the visual apparatus. This study aims to assess the visual outcomes for patients with parasellar meningioma following FSRT.

METHODS

A retrospective, non-comparative case series of 13 patients with parasellar meningiomas who were treated in one institution with FSRT between January 1995 and January 2001.

RESULTS

13 patients (26 eyes) were followed for a mean of 2 years. Visual acuity improved in four eyes (12.5%), remained stable in 18 eyes (75%), and worsened in three eyes (12.5%). Visual field improved in 15 eyes (57%), remained stable in six eyes (23%), and worsened in four eyes (15%). No adverse visual outcome occurred as a result of radiation.

CONCLUSION

These preliminary findings suggest that FSRT is a safe and effective treatment for parasellar meningiomas.

Skull base surgery for benign skull base tumors

The use of skull base techniques in the treatment of benign skull base tumors has allowed access to areas of the brain once considered inaccessible. The most common benign skull base tumors encountered in neurosurgical practice are benign meningiomas, schwannomas, and glomus jugulare tumors. Gross total resection of these lesions gives patients the best possible chance of a cure. In this paper, we review the rationale for the use of skull base surgery techniques for benign skull base tumors.

Stereotactic radiosurgery for patients with solid brain metastases: current status

The goal of this article is to provide a contemporary update on the use of stereotactic radiosurgery (SRS) for the treatment of intracranial metastatic disease. We discuss the rationale for employing SRS in brain metastases and describe the critical factors that predict outcome. We highlight the main clinical indications for SRS including treatment of recurrent brain metastases after previous whole brain radiation therapy (WBRT), as a boost after WBRT, and as sole therapy for newly diagnosed tumors. For each clinical scenario, we offer a treatment algorithm based on our clinical experience. The article also addresses the most common complications associated with SRS and their treatment.

Discrepancy between lesion distributions on methionine PET and MR images in patients with glioblastoma multiforme: insight from a PET and MR fusion image study

OBJECTIVE

To examine (11)C-methyl methionine (MET) accumulation on positron emission tomographic (PET) imaging of glioblastoma multiforme to determine the distribution of metabolic abnormality compared with magnetic resonance imaging (MRI).

METHODS

Contemporaneous MRI was superimposed on corresponding MET-PET images in 10 patients with newly diagnosed glioblastoma multiforme before treatment. Differences between the extended area of MET accumulation on PET imaging (MET area), the gadolinium (Gd) enhanced area on T1 weighted images (Gd area), and the abnormal high signal intensity area on T2 weighted images (T2-high area) were assessed.

RESULTS

The MET area was larger than the Gd area and included the entire Gd area. The discrepancy in volume between the MET and Gd areas became greater with increasing tumour diameter. On average, 58.6% of the MET area was located within the Gd area, 90.1% within 10 mm outside the Gd area, 98.1% within 20 mm, and 99.8% within 30 mm. A newly developed Gd area had emerged in five of the 10 cases up to the time of study. In three of the five cases this was in the MET area even after complete surgical resection of the Gd area on the initial MRI; in the remaining two it originated in the residual Gd area after surgery. In all cases, the T2-high area was larger than the MET area. The MET area extended partly beyond the T2-high area in nine cases, and was completely within it in one.

CONCLUSIONS

Glioblastoma multiforme cells may extend over the Gd area and more widely with increasing tumour size on Gd-MRI. The T2-high area includes the greater part of the tumour but not its entire area. The methods reported may be useful in planning surgical resection, biopsy, or radiosurgery.

Stereotactic radiosurgery for primary trigeminal neuralgia: state of the evidence and recommendations for future reports

OBJECTIVE

To identify systematically all the studies reporting outcomes and complications of stereotactic radiosurgery for trigeminal neuralgia and to evaluate them against predefined quality criteria.

METHODS

Inclusion criteria for outcome analysis included thorough demographic documentation, defined diagnostic and outcome criteria, a minimum of 30 patients treated with 12 months median/mean follow up, not more than 20% lost to follow up, Kaplan-Meier actuarial analysis, primary trigeminal neuralgia, not more than 10% of patients retreated for failure or early recurrence, and minimum dose of 70 Gy.

RESULTS

Of 38 studies identified, four could be used to evaluate rates of pain relief on a yearly basis, and two for actuarial rates of complete pain relief; seven provided data on latencies and 18 were used to evaluate complications. Pain relief typically occurs within three months. Complete relief is initially achieved by three quarters of the patients, but half maintain this outcome at three years. One half or less can permanently stop drug treatments. Sensory disturbance, including anaesthesia dolorosa, is the most frequent complication of stereotactic radiosurgery.

CONCLUSIONS

Outcomes after stereotactic radiosurgery appear in line with other ablative techniques. Results are better when it is used as primary treatment in patients with typical symptoms. Current data are largely observational and the quality is generally poor. This technique should be evaluated in a randomised, controlled trial with universal outcome measures, actuarial methodology, and validated measures of patient satisfaction and quality of life.

Quality of coverage: conformity measures for stereotactic radiosurgery

In radiosurgery, conformity indices are often used to compare competing plans, evaluate treatment techniques, and assess clinical complications. Several different indices have been reported to measure the conformity of the prescription isodose to the target volume. The PITV recommended in the Radiation Therapy Oncology Group (RTOG) radiosurgery guidelines, defined as the ratio of the prescription isodose volume (PI) over the target volume (TV), is probably the most frequently quoted. However, these currently used conformity indices depend on target size and shape complexity. The objectives of this study are to systematically investigate the influence of target size and shape complexity on existing conformity indices, and to propose a different conformity index–the conformity distance index (CDI). The CDI is defined as the average distance between the target and the prescription isodose line. This study examines five case groups with volumes of 0.3, 1.0, 3.0, 10.0, and 30.0 cm³. Each case group includes four simulated shapes: a sphere, a moderate ellipsoid, an extreme ellipsoid, and a concave “C” shape. Prescription dose coverages are generated for three simplified clinical scenarios, i.e., the PI completely covers the TV with 1 and 2 mm margins, and the PI over‐covers one half of the TV with a 1 mm margin and under‐covers the other half with a 1 mm margin. Existing conformity indices and the CDI are calculated for these five case groups as well as seven clinical cases. When these values are compared, the RTOG PITV conformity index and other similar conformity measures have much higher values than the CDI for smaller and more complex shapes. With the same quality of prescription dose coverage, the CDI yields a consistent conformity measure. For the seven clinical cases, we also find that the same PITV values can be associated with very different conformity qualities while the CDI predicts the conformity quality accurately. In summary, the proposed CDI provides more consistent and accurate conformity measurements for all target sizes and shapes studied, and therefore will be a more useful conformity index for irregularly shaped targets.

PACS number(s): 87.90.+y, 87.53.Ly

Safety of multiple stereotactic radiosurgery treatments for multiple brain lesions

BACKGROUND

Stereotactic radiosurgery (SRS) is a widely used therapy for multiple brain lesions, and studies have clearly established the safety and efficacy of single-dose SRS. However, as patient survival has increased, the recurrence of tumors and the development of metastases to new sites within the brain have made it desirable to repeat treatments over time. The cumulative toxicity of multi-isocenter, multiple treatments has not been well defined. We have retrospectively studied 10 patients who received multiple SRS treatments for multiple brain lesions to assess the cumulative toxicity of these treatments.

METHODS

In a retrospective review of all patients treated with SRS using the X-knife (Radionics, Burlington, MA) at Westchester Medical Center/New York Medical College between December 1995 and December 2000, 10 patients were identified who received at least two treatments to at least 3 isocenters and had a minimum follow-up period of 6 months. Image fusion technique was used to determine cumulative doses to targeted lesions, whole brain and critical brain structures. Toxicities and complications were identified by chart and radiological review.

RESULTS

The average of the maximum doses (cGy) to a point within the whole brain was 2402 (range 1617-3953); to the brainstem, 1059 (range 48-4126); to the right optic nerve, 223 (range 14-1012); to the left optic nerve, 159 (range 17-475); and to the optic chiasm, 219 (range 15-909). There were no focal neurological toxicities, including visual disturbances, cranial nerve palsies, or ataxia in any of the 10 patients. There were also no global toxicities, including cognitive decline or secondary tumors. Only one patient developed seizures that were difficult to control in association with radiation necrosis.

CONCLUSIONS

Multiple SRS treatments at the cumulative doses used in our study are a safe therapy for patients with multiple brain lesions.

Spontaneous haemorrhage into metastatic brain tumours after stereotactic radiosurgery using a linear accelerator

OBJECTIVE

To determine the incidence and clinical characteristics of spontaneous haemorrhage into metastatic brain tumours after radiosurgery.

METHODS

Intratumour haemorrhage rate, clinical features, and treatment were evaluated in 54 patients with 131 brain metastases of varying origin who were treated using linear accelerator radiosurgery. The marginal dose was maintained constant at 20 or 25 Gy, irrespective of tumour size.

RESULTS

Haemorrhage was identified in 7.4% of the metastases (five tumours in four patients) before radiosurgery and in 18.5% (10 tumours in 10 patients) after radiosurgery. In three cases, haemorrhage into the tumour after radiosurgery was symptomatic. Half the haemorrhages occurred within one month of radiosurgery. The changes in tumour size observed at the time of haemorrhage were an increase in one tumour, no change in five, and a decrease in four. Haemorrhage into a tumour after radiosurgery was more likely to occur in female patients, in tumours with a larger volume on pretreatment neuroimaging, and in tumours treated with a larger number of isocentres or a higher maximum dose. Haemorrhagic features in the patients or their tumours on presurgical assessment were not disposing factors to haemorrhage after radiosurgery.

CONCLUSIONS

When larger brain metastases are aggressively treated by radiosurgery, better local control may be attained but there may also be a higher risk of haemorrhage soon after the treatment.

Modern treatment of acromegaly

Acromegaly is an endocrine disorder characterised by increased morbidity and mortality. It is usually caused by a growth hormone secreting pituitary adenoma and is manifested by a variety of clinical features. Surgery is usually the treatment of choice, however over the last few years, several new methods of treatment have been developed. A recent consensus on the targets for treatment has led to multiple studies being conducted to assess the efficacy of the currently available options. This review examines the evidence for and against these treatments.

Three-dimensional conformal radiotherapy for astrocytic tumors involving the eloquent area in children and young adults

PURPOSE

Although a gross total removal of astrocytic tumors offers a favorable prognosis, it is often difficult to achieve in the eloquent area of the brain. This study was conducted to investigate the possible gain of three-dimensional conformal radiotherapy (3DCRT) for astrocytic tumors located in the eloquent area in children and young adults.

MATERIALS AND METHODS

Twenty patients with astrocytic tumors received the radiotherapy. The median age was 17 years, ranging from 4 to 30 years. Fourteen low-grade tumors (seven pilocytic and seven diffuse), and six high-grade tumors (five anaplastic, one malignant pilocytic) were included. Tumors were located at the thalamus/hypothalamus in 12 cases, optic tract in one case, and the deep cerebral/cerebellar hemisphere in seven cases. A specific fixation device was used for 3DCRT. Forty-six Gy for low-grade tumors and 54 Gy for high-grade astrocytomas with 1.8-2.0 Gy per fraction were in principle employed as the standard regimen. Nominal radiotherapy fields ranged from 2.0 x 2.0 to 15.0 x 11.0 cm2. The median follow-up period was 42 months, ranging from 3 to 108 months.

RESULTS

The actuarial survival rate at 5 years was 68% +/- 13% for all patients. The actuarial survival rate for low-grade glioma was 79% +/- 14% at 5 years and 50% +/- 20% at 3 years for high-grade glioma. The actual progression-free survival rate was 83% +/- 11% at 5 years for low-grade glioma and 50% +/- 20% for high-grade glioma. A complete response was obtained in three (21%) of 14 patients with low-grade astrocytic tumors. Two patients with low-grade tumors and four of six with high-grade tumors died due to tumor progression with infield relapse but not marginal relapse. Twelve survivors with low-grade tumors showed no signs of relapse and no neurological, hormonal, or cognitive deterioration after radiotherapy and were able to attend their school or continue with a full-time job.

CONCLUSIONS

3DCRT is safe and effective for low-grade astrocytic tumors located in the eloquent area in children and young adults.

Management of essential tremor

Essential tremor (ET) is the most prevalent tremor syndrome. It commonly affects the hands, head, voice, and other body parts. Appropriate management begins with correct diagnosis. Primidone and propranolol are the first-line medications for the treatment for ET, but several other medications may also provide benefit. In patients with medically refractory tremor, alternative therapies, including surgery or injections of botulinum toxin, may be considered.

Trigeminal neuralgia and other neuropathic pain syndromes of the head and face

Trigeminal neuralgia is the most common craniofacial pain syndrome of neuropathic origin. Although the diagnosis remains based exclusively on history and symptomatology, modern diagnostic techniques, particularly high-resolution magnetic resonance imaging, provides valuable new insight into the pathophysiology of these cases with additional implications for therapeutic strategies. Other neuropathic syndromes affect the trigeminal nerve and warrant different treatments with varied rates of success. Rarely, neuralgias of other cranial nerves mimic trigeminal neuralgia. Finally, it is imperative to distinguish atypical facial pains from these neuropathic syndromes to avoid unsuccessful therapies.

Effect of breathing a hyperoxic hypercapnic gas mixture on the oxygenation of meningiomas; preliminary results

For meningiomas in which complete resection is impossible stereotactic radiosurgery and radiotherapy are increasingly important therapeutical options. The radiosensitivity of meningiomas may be improved by increasing tumor oxygen levels. Hyperoxygenating agents, like breathing a hyperoxic hypercapnic gas mixture, have already been applied successfully in the treatment of other tumors. The aim of this study was to explore the effect of breathing a hyperoxic hypercapnic gas mixture on tumor blood oxygenation of meningiomas using magnetic resonance imaging (MRI) methods. Three patients with convexity meningiomas were each measured twice; with and without breathing the hyperoxic hypercapnic gas mixture. Tumor blood oxygenation changes were measured using blood oxygen level dependent MR imaging. Dynamic contrast enhanced MRI was used to assess functional changes of tumor vasculature. A significant increase in tumor blood oxygenation was observed under hypercapnic hyperoxic conditions in all patients, exceeding the increase in normal brain tissue. It was concluded that the oxygenation status of meningiomas can be improved by breathing a hyperoxic hypercapnic gas mixture.

Hypophysopexy technique for radiosurgical treatment of cavernous sinus pituitary adenoma

Stereotactic radiosurgery is being used with increased frequency in the treatment of residual or recurrent pituitary adenomas. The major risk associated with radiosurgical treatment of residual or recurrent pituitary tumor adjacent to normal functional pituitary gland is radiation of the pituitary, which frequently leads to the development of hypopituitarism. The authors describe a technique of pituitary transposition to reduce the radiation dose to the normal pituitary gland in cases of planned radiosurgical treatment of residual pituitary adenoma within the cavernous sinus. A sellar exploration for tumor resection is performed, the pituitary gland is transposed from the region of the cavernous sinus, and a fat and fascia graft is interposed between the normal pituitary gland and the residual tumor in the cavernous sinus. The residual tumor may then be treated with stereotactic radiosurgery. The increased distance between the normal pituitary gland and the residual tumor facilitates treatment of the tumor with radiosurgery and reduces the radiation to the normal pituitary gland. An illustrative case of a young female with recurrent acromegaly and a pituitary adenoma invading the cavernous sinus is described.

Medical management of prolactin-secreting pituitary adenomas

Prolactinomas are a common cause of reproductive/sexual dysfunction. Once other causes of hyperprolactinemia have been excluded with a careful history and physical examination, routine chemistries, a pregnancy test and a TSH, imaging with MRI or CT will delineate the size and extent of the tumor. Medical therapy is the initial treatment of choice. When infertility is the primary indication for treatment, bromocriptine use has an extensive safety experience and is preferred. However, for other indications, cabergoline appears to be more efficacious and better tolerated. Transsphenoidal surgery remains an option, especially for patients with microadenomas, when medical therapy is ineffective.

Radiation therapy for Cushing's disease: a review

Because patients with Cushing's disease have an increased morbidity and an age-corrected mortality, treatment is generally started as soon as possible. The goal of treatment in these patients is to induce remission. Although a variety of treatments are available, pituitary radiation is a good option for aggressive Cushing's disease that fails to respond to surgery, disease that invades the cavernous sinus, and disease that relapses following an initial remission. Conventional radiation therapy, stereotactic radiosurgery, fractionated stereotactic radiation therapy, and brachytherapy with Yttrium-90 (Y 90) and Gold-198 (Au 198) have been used successfully to treat ACTH-secreting pituitary adenomas in specialized centers. Conventional radiation therapy is the most frequently used method of radiation therapy for Cushing's disease. Stereotactic radiosurgery may be used as an alternative in patients with adenomas that are smaller than 30 mm and located at least 3 to 5 mm from the optic chiasm. Fractionated stereotactic radiation therapy is an alternative to radiosurgery while interstitial pituitary irradiation is an alternative to surgical resection in invasive tumors. Hypopituitarism is the most common side effect of pituitary irradiation. This article will review the role of radiation in the primary and secondary treatment in patients with Cushing's disease caused by pituitary adenomas.

Management of recurrent pituitary cysts with pituitary-nasal drain

Pituitary cysts are usually craniopharyngiomas or remnants of Rathke's cleft. Histologically craniopharyngiomas are lined by stratified squamous epithelium whereas Rathke's cleft cysts are lined by cuboidal or columnar epithelium. The management of pituitary cysts remains difficult because of the risks associated with attempts at complete removal and the chances of recurrence after inadequate resection. We describe 3 cases of cystic craniopharyngiomas and one case of Rathke's cleft cyst which recurred after surgery and were subsequently managed successfully with pituitary-nasal drains.

Current status and future opportunities for controlling acromegaly

Growth-hormone (GH) secreting adenomas, including acromegaly, account for approximately one-sixth of all pituitary adenomas and are associated with mortality rates at least twice that of the general population. The ultimate goal of therapy for acromegaly is normalization of morbidity and mortality rates achieved through removal or reduction of the tumor mass and normalization of insulin-like growth factor I (IGF-I) levels. Previously published efficacy results of current treatment modalities (surgery, conventional radiation, and medical therapy with dopamine agonists and somatostatin analogs) are often difficult to compare because of the different criteria used to define cure (some of which are now considered inadequate). For each of these modalities, pooled data from a series of acromegaly studies were reviewed for rates of IGF-I normalization, a currently accepted definition of cure. The results showed overall cure rates of approximately 10% for bromocriptine, 34% for cabergoline, 36% for conventional radiation, 50-90% for surgery for microadenomas and less than 50% for macroadenomas, and 54-66% for octreotide. These cure rates based on IGF-I normalization are generally less than those reported for cure based solely on GH levels. Novel new therapies for acromegaly include the somatostatin analog, lanreotide, Gamma Knife radiosurgery, and pegvisomant, the first in its class of new GH receptor antagonists. Although it does not appear that Gamma Knife radiosurgery results in significantly higher cure rates or fewer complications, it does provide a notable improvement in delivery compared with conventional radiation. Early studies have reported IGF-I normalization in 48% of lanreotide-treated patients and up to 97% of pegvisomant-treated.

Current management of prolactinomas

Prolactinomas constitute the largest group of pituitary adenomas in autopsy series. However, their relative incidence in recent surgical series is much less impressive since medical treatment with dopamine agonists is routinely employed, which in many cases leads to tumor shrinkage and normalization of prolactin levels. The clinical symptoms of hyperprolactinemia are menstrual dysfunction and galactorrhea in women and loss of libido and potency in men. Prolactinomas may present also as space occupying sellar mass lesions impinging on the adjacent structures like the pituitary gland, cavernous sinus and optic nerves. The standard primary treatment is medical by dopamine agonists. Prolactinomas are the prototype of tumors, the growth of which can be reliably and safely inhibited by specific drugs other than cytostatic chemotherapy. These unfortunately have side effects, like orthostatic hypotension, nausea and vomiting. The effects induced by dopamine agonists are suppressive but not tumoricidal. Thus, the therapeutic effect is only maintained as long as the drug is administered. Consequently. in most cases, treatment has to be continued life-long with a few exceptions, in whom normoprolactinemia persists even after discontinuation of dopamine agonists. Main indications of surgery in prolactinomas are intolerance of the medication, and tumors not responding to dopamine agonists. Occasionally, these may ultimately require radiation therapy. Remission rates in large series of surgically treated prolactinomas vary between 54% and 86%. In our consecutive series of 540 surgically treated prolactinomas, the normalization rate after transsphenoidal surgery basically depended on the preoperative prolactin levels, tumor size and extension. The remission rate of 82% in microprolactinomas with initial prolactin levels <200 ng/ml would even in small adenomas make one consider surgical treatment as an interesting alternative to long-term medical treatment.

Acromegaly: historical perspectives and current therapy

Soon after the initial description of acromegaly in the late 19th century, neurosurgeons performed the first operative procedures for the disease. Transcranial procedures eventually yielded to the transsphenoidal approach. Reasonably effective medical therapy was introduced in the 1970s and pharmacological progress continues to be realized. It is now recognized that excess growth hormone is associated with significant morbidity and mortality and that biochemical remission improves outcome. Although medical and radiation treatments offer useful adjuncts, surgery provides optimal results.

Gamma knife radiosurgery in the management of patients with acromegaly: a review

Although acromegaly is a rare disease, the need for an effective treatment that is able to induce biochemical cure is an extremely important issue. Unsuccessfully treated acromegaly is associated with increased morbidity and an age-corrected mortality so that early and aggressive therapy to normalize hormonal levels should be instituted at diagnosis. Ideally, the growth hormone-secreting adenoma should be completely resected, with preservation or subsequent restoration of pituitary function. Patients with recurrence or failure after surgery are treated with a second surgery, medical, radiation treatment, or combined modality treatment. Steotactic radiosurgery with gamma knife allows the delivery of focused radiation in a single session to the pituitary tumor that delivers a more biologically effective dose to the tumor than fractionated radiotherapy. Its use as a primary or adjuvant treatment for acromegalics may be more cost effective than medical treatment in these patients. Although it seems to be very effective in controlling growth and secretion of the growth hormone-secreting pituitary adenomas, there is a chance that some major risks from gamma knife radiosurgery might occur. This article will review the role that gamma knife radiosurgery might have in patients with acromegaly.