Radiation sensitivity of visual and oculomotor pathways

Conservative or surgical management of orbital schwannomas: a population-based case series

INTRODUCTION

Orbital schwannomas (OS) are rare occurrences with no more than 500 cases reported in the literature. The tumor's potential to compromise the delicate neuro-ophthalmic structures within the orbit prompts surgical removal. Tumor removal is performed by ophthalmologists, often requiring a multidisciplinary surgical approach. The literature contains a very limited number of cases managed non-surgically. However, the inherent risks of orbital surgery warrant a comparison of the outcomes of conservative and surgical management strategies.

AIMS

To review the national Swedish experience with the management of orbital schwannomas.

METHODS

The study center is the primary Swedish referral center for the multidisciplinary management of orbital tumors, including schwannomas. During the period of 2005 to 2021, 16 patients with an OS diagnosis were managed at the center.

RESULTS

Four patients initially underwent surgery where gross total resection (GTR) was achieved in three (75%) and subtotal resection (STR) in one (25%) case. The remaining 12 patients, who had a low risk of neuro-ophthalmic impairment, were managed conservatively with radiological and clinical examinations at regular intervals. After an average follow-up of 17 months, surgery was performed in three of these cases (25%). No recurrences or tumor growths were detected on radiological follow-ups (mean 50 months), and all patients experienced postoperative improvement at clinical follow-up (mean 65 months). The remainder of the conservatively treated patients (n=9) experienced no clinical progression (mean 30 months). A slight radiological tumor progression was detected in one patient after 17 months.

CONCLUSION

There were no differences in long-term outcome between patients who had been managed with early surgery and those operated later after an initially conservative management. Conservatively treated patients had minimal to no symptoms and remained clinically stable throughout the follow-up period. Based on these findings, conservative management may successfully be adopted in cases with mild symptoms, no signs of compressive optic neuropathy and low risk of neuro-ophthalmic impairment. Conversion to surgical management is indicated upon clinical deterioration or tumor growth. Based on the findings of this study a decision tree for the management of orbital schwannomas is suggested.

Single fraction and hypofractionated radiosurgery for perioptic meningiomas-tumor control and visual outcomes: a systematic review and meta-analysis

Perioptic meningiomas, defined as those that are less than 3 mm from the optic apparatus, are challenging to treat with stereotactic radiosurgery (SRS). Tumor control must be weighed against the risk of radiation-induced optic neuropathy (RION), as both tumor progression and RION can lead to visual decline. We performed a systematic review and meta-analysis of single fraction SRS and hypofractionated radiosurgery (hfRS) for perioptic meningiomas, evaluating tumor control and visual preservation rates. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we reviewed articles published between 1968 and December 8, 2022. We retained 5 studies reporting 865 patients, 438 cases treated in single fraction, while 427 with hfRS. For single fraction SRS, the overall rate of tumor control was 95.1%, with actuarial rates at 5 and 10 years of 96% and 89%, respectively; tumor progression was 7.7%. The rate of visual stability was 90.4%, including visual improvement in 29.3%. The rate of visual decline was 9.6%, including blindness in 1.2%. For hfRS, the overall rate of tumor control was 95.6% (range 92.1-99.1, p < 0.001); tumor progression was 4.4% (range 0.9-7.9, p = 0.01). Overall rate of visual stability was 94.9% (range 90.9-98.9, p < 0.001), including visual improvement in 22.7% (range 5.0-40.3, p = 0.01); visual decline was 5.1% (range 1.1-9.1, p = 0.013). SRS is an effective and safe treatment option for perioptic meningiomas. Both hypofractionated regimens and single fraction SRS can be considered.

Effects and Assessment of the Optic Pathway After Management with Stereotactic Radiosurgery for Intracranial Tumors: A Comprehensive Literature Review

Intracranial tumors are treated through a minimally invasive procedure called stereotactic radiosurgery (SRS), which uses precisely targeted radiation beams. When SRS is used to treat tumors in or near the optic pathway, which is responsible for transmitting visual information from the eyes to the brain, it is essential to assess the effects of treatment on visual function. The optic pathway is considered relatively radiation-sensitive, and high doses of radiation can lead to visual impairment or loss. Various methods can be used to assess the effects of SRS on the optic pathway, including visual acuity testing, visual field testing, and imaging studies. These assessments can be performed before and after treatment to track changes in visual function and detect potential complications or side effects. Assessing the optic pathway after management with SRS for intracranial tumors is essential to the treatment process to ensure that patients receive the best possible outcomes while minimizing the risk of complications. Close collaboration between the multidisciplinary team is often necessary to optimize treatment planning and monitoring of treatment response. In this review, we conducted an extensive analysis of the effects of radiation in patients with intracranial tumors after receiving radiotherapy.

Single fraction stereotactic radiosurgery and fractionated stereotactic radiotherapy provide equal prognosis with overall survival in patients with brain metastases at diagnosis without surgery at primary site

Background and purpose

Stereotactic radiosurgery (SRS) and fractionated stereotactic radiation therapy (SRT) are both treatments shown to be effective in treating brain metastases (BMs). However, it is unknown how these treatments compare in effectiveness and safety in cancer patients with BMs regardless of the primary cancer. The main objective of this study is to investigate the SRS and SRT treatments' associations with the overall survival (OS) of patients diagnosed with BMs using the National Cancer Database (NCDB).

Materials and methods

Patients in the NCDB with breast cancer, non-small cell lung cancer, small cell lung cancer, other lung cancers, melanoma, colorectal cancer, or kidney cancer who had BMs at the time of their primary cancer diagnosis and received either SRS or SRT as treatment for their BMs were included in the study. We analyzed OS with a Cox proportional hazard analysis that adjusted variables associated with improved OS during univariable analysis.

Results

Of the total 6,961 patients that fit the criteria for the study, 5,423 (77.9%) received SRS and 1,538 (22.1%) received SRT. Patients who received SRS treatment had a median survival time of 10.9 (95% CI [10.5-11.3]), and those who received SRT treatment had a median survival time of 11.3 (95% CI [10.4-12.3]) months. This difference was not found to be significant (Log-rank P = 0.31). Multivariable Cox proportional hazard analysis did not yield a significant difference between the treatments' associations with OS (Hazard Ratio: 0.942, CI 95% [0.882-1.006]; P = .08) or SRS vs. SRT.

Conclusions

In this analysis, SRS and SRT did not show a significant difference in their associations with OS. Future studies investigating the neurotoxicity risks of SRS as compared to SRT are warranted.

Orbital schwannoma management: a case report, literature review, and potential paradigm shift

PURPOSE

To present a case of orbital schwannoma and assess the literature on treatment modalities.

METHODS

A MEDLINE literature search for cases of orbital schwannomas was performed using the PubMed search tool using the search terms "orbital schwannoma" and "orbital neurilemmoma." Papers were included if they were peer-reviewed, published in English, discussed management, and included the search terms. Each article was rated using the scale developed by the British Centre for Evidence-Based Medicine. In addition, we present a case report of an orbital schwannoma.

RESULTS

A total of 428 articles were found. 102 met the criteria for inclusion. Only two articles met Level 1 evidence and 16 were important to the clinical care process. We report a case of a biopsy-proven orbital schwannoma managed conservatively with observation over a 4-year period due to risk of cosmetic disfigurement with tumor removal. There has been no change in tumor size and no associated complications during follow up.

CONCLUSIONS

There is a paucity of data on the natural history of orbital schwannomas. Based on our review of the literature, we recommend observation for asymptomatic or minimally symptomatic orbital schwannomas with minimal growth over an extended period of time. For rapidly growing tumors or large tumors affecting key structures causing visual loss, diplopia, aesthetic disfigurement, or patient discomfort, a more aggressive approach may be necessary.

Meningiomas

Meningiomas arise in various locations. Convexity tumors are relatively simple to remove. Skull base tumors and tumors adjacent to the major cerebral veins and venous sinuses can be very difficult to extirpate. Attempts at radical resection can lead to serious morbidity. The combination of bulk reduction using microsurgery followed by GKNS gives greatly improved survival and very low morbidity. With smaller tumors, GKNS may be used as the primary treatment. Increasing numbers of asymptomatic meningiomas are demonstrated either as an unexpected finding or as a residual or recurrent tumor after surgery. In all of these situations, GKNS gives a better result than observation or reoperation.

Brain metastases: An update on the multi-disciplinary approach of clinical management

IMPORTANCE

Brain metastasis (BM) is the most common malignant intracranial neoplasm in adults with over 100,000 new cases annually in the United States and outnumbering primary brain tumors 10:1.

OBSERVATIONS

The incidence of BM in adult cancer patients ranges from 10-40%, and is increasing with improved surveillance, effective systemic therapy, and an aging population. The overall prognosis of cancer patients is largely dependent on the presence or absence of brain metastasis, and therefore, a timely and accurate diagnosis is crucial for improving long-term outcomes, especially in the current era of significantly improved systemic therapy for many common cancers. BM should be suspected in any cancer patient who develops new neurological deficits or behavioral abnormalities. Gadolinium enhanced MRI is the preferred imaging technique and BM must be distinguished from other pathologies. Large, symptomatic lesion(s) in patients with good functional status are best treated with surgery and stereotactic radiosurgery (SRS). Due to neurocognitive side effects and improved overall survival of cancer patients, whole brain radiotherapy (WBRT) is reserved as salvage therapy for patients with multiple lesions or as palliation. Newer approaches including multi-lesion stereotactic surgery, targeted therapy, and immunotherapy are also being investigated to improve outcomes while preserving quality of life.

CONCLUSION

With the significant advancements in the systemic treatment for cancer patients, addressing BM effectively is critical for overall survival. In addition to patient's performance status, therapeutic approach should be based on the type of primary tumor and associated molecular profile as well as the size, number, and location of metastatic lesion(s).

Neuro-ophthalmologic outcomes of standard versus hypo-fractionated stereotactic radiotherapy of AVPM

BACKGROUND

Most anterior visual pathway meningiomas (AVPM) are benign and slow-growing, but these tumors may affect visual functions, including visual acuity (VA) and visual field (VF). Due to location, most are treated non-surgically by fractionated stereotactic radiotherapy (FSRT), aiming to prevent tumor progression and visual functions deterioration. Unfortunately, FSRT in itself may affect visual functions. The current preferred treatment regimen (in terms of safety and effectiveness) is undetermined. While most cases are treated with conventional fractionation (cFSRT)-50.4-54 Gy in 28-30 fractions of 1.8-2 Gy, advances in technology have allowed shortening of total treatment length to hypofractionation (hSRT)-25-27 Gy in 3-5 fractions of 5-9 Gy. Our aim was to evaluate the association of radiotherapy regimen for treating AVPM (cFSRT vs. hSRT) with visual function outcomes (VA, VF) at the last neuro-ophthalmologic evaluation.

METHODS

We conducted a retrospective cohort study of AVPM cases treated at Sheba Medical Center during 2004-2015. We compared cFSRT and hSRT regimens regarding visual function (VA, VF) outcomes at the last neuro-ophthalmologic evaluation. VA was determined by the logarithm of the minimum angle of resolution (LogMAR). VF was determined by the mean deviation (MD). A clinically relevant change in VA was defined as 0.2 LogMAR.

RESULTS

48 patients (13 receiving hSRT, 35 receiving cFSRT) were included, with a median follow-up of 55 months. No significant difference was evident regarding LogMAR or MD of involved eyes at the last evaluation. Six (17%) patients in the cFSRT group experienced clinically relevant VA deterioration in the involved eye, compared with six (46%) in hSRT (p = 0.06).

CONCLUSION

Our findings, using comprehensive and meticulous investigation of visual outcomes, suggest that hSRT may be associated with higher risk for VA and VF deterioration in AVPM especially in ONSM. We recommend the use of cFSRT for ONSM.

Long-term disease control and treatment outcomes of stereotactic radiosurgery in cavernous sinus meningiomas

BACKGROUND

Most of the current knowledge on the clinical effects of stereotactic radiosurgery (SRS) on the treatment of cavernous sinus meningiomas (CSM) is based on series with limited follow-up. However, determining the role of radiation in a tumor with slow disease progression such as CSM necessitates long term follow up.

OBJECTIVE

To review and pool metadata in the literature to determine the long-term outcomes of SRS with respect to clinical and radiographic tumor control of CSM.

METHODS

A systematic search was conducted following MOOSE guidelines. Results were screened against predefined criteria, which excluded studies with a median follow-up less than 5 years. The incidences of each outcome were calculated using random-effects metanalysis of proportions.

RESULTS

Seven studies met the inclusion criteria, comprising 645 patients. The median follow-up was 74 months (range 62-87). Progression-free-survival at 5, 10, and 15 years was 93.4% (95% CI 89.1-96.7%), 84.9% (95% CI 77-91.4%), and 81.3% (95% CI 74-87.7%), respectively. Clinical response to SRS at last follow-up defined as improvement of cranial nerve deficits was found in in 36.4% (95% CI 26.3-47.1%) of patients, while worsening or onset of new cranial nerve deficits was found in 11.5% (95% CI 7.9-15.7%). Radiological regression was found in 57.8% (95% CI 43-71.8%), while tumor progression was found in 8.5% (95% CI 5.2-12.6%).

CONCLUSION

SRS achieves excellent disease control and radiographic response in CSM. Although the risk of long-term cranial neuropathies is minimal, it is relatively higher to what has been previously reported in early series with limited follow-up.

Clinical outcomes of fractionated stereotactic radiosurgery in treating perioptic meningiomas and schwannomas: A single-institutional experience

Application of radiosurgery to the newly diagnosed or post-operative residual perioptic lesions has been proved to improve tumor control. However, risk of vision injury induced by radiosurgery may increase substantially if the radiation dose is too high or tumor is close to the optic apparatus. The purpose of this study was to evaluate the safety and the effectiveness of fractionated stereotactic radiosurgery (FSRS) for perioptic tumors. We retrospectively analyzed 60 consecutive patients with 53 meningiomas and 7 schwannomas treated with FSRS between October 2007 and February 2020. We administered a marginal dose of 6-7 Gy (mean 6.8 Gy) per fraction and delivered 3 fractions in 3 consecutive days. The median tumor volume was 6.31 cm³ (range 0.3-58.23 cm³). The mean minimum lesion-optic distance (MLOD) is 0.85 mm (range 0-3 mm). After mean follow-up period of 69.6 months (range 6.82-156.32 months; median 58.9 months), the tumor control rates at 1, 3, 5, 8 and 13 years were 98.3%, 93.4%, 90.60%, 88.4% and 88.4%, respectively. Four out of the 60 tumors (6.7%) experienced a transient volume increase after FSRS. None of the patients developed visual impairment related to radiation induced optic neuropathy (RION) after FSRS. In conclusion, FSRS offers an alternative treatment option in treating perioptic meningiomas and schwannomas with acceptable tumor control rates and good visual preservation in the present study.

Stereotactic Radiosurgery for Residual and Recurrent Nonfunctioning Pituitary Adenomas: A Contemporary Case Series of GammaKnife and CyberKnife Radiosurgery

BACKGROUND

In patients with residual or recurrent nonfunctioning pituitary adenomas (NFPAs) after transsphenoidal resection, both GammaKnife (GKRS) and CyberKnife (CKRS) stereotactic radiosurgery (SRS) are viable treatment options.

OBJECTIVES

We report a retrospective single center series comparing assessing the effectiveness and complications from of these 2 commonly used SRS techniques.

METHODS

A total of 53 patients with prior surgical resection and residual or recurrent NFPAs who underwent GKRS or CKRS and minimum 3-month follow-up between January 2002 and February 2017 at a single center were identified.

RESULTS

A total of 34 patients underwent GKRS and 19 received CKRS. CKRS patients had a larger maximal tumor diameter (P = 0.005) and tumor volume treated (P = 0.001). Differences between GKRS and CKRS treatment parameters included target volume, target volume treated, prescribed dose, maximum dose, prescription isodose line, and conformity index (P < 0.05). The mean follow-up time was 53.74 months for GKRS and 41.48 months for CKRS patients. Tumor progression developed in 6% of cases after GKRS versus 5% after CKRS. The mean progression-free survival was 48.44 months after GKRS and 38.57 months after CKRS (P = 0.61). Five-year actuarial tumor control rates were 91% after GKRS versus 89% after CKRS (P > 0.99). There were no differences in worsened vision or rates of hypopituitarism.

CONCLUSIONS

In patients undergoing single fraction GKRS versus fractionated CKRS for NFPAs, both modalities had similar rates of tumor control, new hypopituitarism, and visual morbidity despite varying indications. This study validates the versatile use of these 2 SRS modalities for patients meeting their relative criteria, especially based on proximity to the optic apparatus and normal pituitary gland.

A Case of Thymic Carcinoma with Bone and Cerebral Metastases Treated with Stereotactic Radiosurgery and Chemotherapy

Patient: Female, 63

Final Diagnosis: Thymic carcinoma

Symptoms: Hip pain

Medication: —

Clinical Procedure: —

Specialty: Oncology

Orbital apex venous cavernous malformation with optic neuropathy: treatment with multisession gamma knife radiosurgery

PURPOSE

To evaluate the efficacy and safety of multisession gamma knife radiosurgery (GKRS) for orbital apex venous cavernous malformation causing optic neuropathy.

METHODS

Retrospective cohort study in a single tertiary institution from January 2007 to December 2016 on patients who underwent multisession GKRS for orbital apex venous cavernous malformations causing optic neuropathy.

RESULTS

There were 12 patients included in our study. The mean age was 40.2±14.5 years, and men comprised 66.7% (n=8). Decrease in visual acuity (83.3%) was the most common symptom at presentation. The mean clinical follow-up was 28.5 months. Ten (83.3%) of the 12 patients had improvement in best corrected visual acuity. Of the 10 patients with pre-existing relative afferent pupillary defect (RAPD), 6 (60%) had complete resolution of RAPD. Of the 12 patients with visual field defect, 7 (58.3%) had complete resolution, 3 (25%) had partial improvement, while 2 (16.7%) remained unchanged due to optic atrophy from long-standing compressive optic neuropathy. Mean proptosis reduced from 2.3±1.7 mm pre-GKRS to 0.5±1.3 mm post-GKRS (p=0.005). Tumour shrinkage was observed in all patients. The mean tumour volume at the time of GKRS was 3104 mm³ (range 221-8500 mm³), which reduced to 658 mm³ (range 120-3350 mm³) at last follow-up. None of the patients experienced GKRS-related ocular morbidity during the follow-up period.

CONCLUSION

Multisession GKRS has shown to be an effective and safe option for the treatment of orbital apex venous cavernous malformations causing optic neuropathy, with significant improvement in ophthalmic outcomes and reduction in tumour volume.

Single- and Multi-Fraction Stereotactic Radiosurgery Dose Tolerances of the Optic Pathways

PURPOSE

Dosimetric and clinical predictors of radiation-induced optic nerve/chiasm neuropathy (RION) after single-fraction stereotactic radiosurgery (SRS) or hypofractionated (2-5 fractions) radiosurgery (fSRS) were analyzed from pooled data that were extracted from published reports (PubMed indexed from 1990 to June 2015). This study was undertaken as part of the American Association of Physicists in Medicine Working Group on Stereotactic Body Radiotherapy, investigating normal tissue complication probability (NTCP) after hypofractionated radiation.

METHODS AND MATERIALS

Eligible studies described dose delivered to optic nerve/chiasm and provided crude or actuarial toxicity risks, with visual endpoints (ie, loss of visual acuity, alterations in visual fields, and/or blindness/complete vision loss). Studies of patients with optic nerve sheath tumors, optic nerve gliomas, or ocular/uveal melanoma were excluded to obviate direct tumor effects on visual outcomes, as were studies not specifying causes of vision loss (ie, tumor progression vs RION).

RESULTS

Thirty-four studies (1578 patients) were analyzed. Histologies included pituitary adenoma, cavernous sinus meningioma, craniopharyngioma, and malignant skull base tumors. Prior resection (76% of patients) did not correlate with RION risk (P = .66). Prior irradiation (6% of patients) was associated with a crude 10-fold increased RION risk versus no prior radiation therapy. In patients with no prior radiation therapy receiving SRS/fSRS in 1-5 fractions, optic apparatus maximum point doses resulting in <1% RION risks include 12 Gy in 1 fraction (which is greater than our recommendation of 10 Gy in 1 fraction), 20 Gy in 3 fractions, and 25 Gy in 5 fractions. Omitting multi-fraction data (and thereby eliminating uncertainties associated with dose conversions), a single-fraction dose of 10 Gy was associated with a 1% RION risk. Insufficient details precluded modeling of NTCP risks after prior radiation therapy.

CONCLUSIONS

Optic apparatus NTCP and tolerance doses after single- and multi-fraction stereotactic radiosurgery are presented. Additional standardized dosimetric and toxicity reporting is needed to facilitate future pooled analyses and better define RION NTCP after SRS/fSRS.

The impact of different stereotactic radiation therapy regimens for brain metastases on local control and toxicity

Purpose

Stereotactic radiation therapy (SRT) enables focused, short course, high dose per fraction radiation delivery to brain tumors that are less ideal for single fraction treatment because of size, shape, or close proximity to sensitive structures. We sought to identify optimal SRT treatment regimens for maximizing local control while minimizing morbidity.

Methods and materials

We performed a retrospective review of patients treated with SRT for solid brain metastases using variable dose schedules between 2001 and 2011 at 3 academic hospitals. Endpoints included (1) local control, (2) acute toxicity (Common Toxicity Criteria for Adverse Events v3.0), and (3) symptomatic radionecrosis. Kaplan-Meier and a competing risks methodology were used to estimate the actuarial rate of local failure and assess the association of clinical and treatment covariates with time to local failure.

Results

A total of 156 patients was identified. Common tumor histologies included breast (21%), non-small cell lung (32%), melanoma (22%), small cell lung (9%), and renal cell carcinoma (6%). The majority of lesions were supratentorial (57%). Median target volume was 3.99 mL (range, 0.04-58.42). Median total SRT dose was 25 Gy (range, 12-36), median fractional dose was 5 Gy (range, 2.5-11), and median number of fractions was 5 (range, 2-10). Cumulative incidence of local progression at 3, 6, 12, 18, and 24 months was 11%, 22%, 29%, 34%, and 36%. Total prescription dose was the only factor significantly associated with time to local progression on univariate (P = .02) and multivariable analysis (P = .01, adjusted hazards ratio, 0.87). Five patients experienced seizures within 10 days of SRT and 5 patients developed radionecrosis. All patients with documented radionecrosis received prior radiation to the index lesion.

Conclusions

Our series of SRT for brain metastases found total prescription dose to be the only factor associated with local control. Both acute and long-term toxicity events from SRT were modest.

Clinical and Radiologic Outcome of Gamma Knife Radiosurgery on Nonfunctioning Pituitary Adenomas

Objective To elucidate the role of Gamma Knife radiosurgery (GKRS) in the management of nonfunctioning pituitary adenomas (NFAs). Materials and Methods A retrospective review of 57 consecutive patients spanning 2000 to 2013 with NFAs was performed. Of 57 patients, 53 patients had recurrent or residual tumors after microsurgical resection. The study population was evaluated clinically and radiographically after GKRS treatment. The median follow-up time was 45.57 months. Results GKRS in pituitary adenomas showed significant variations in tumor growth control (decreased in 32 patients [56.1%], arrested growth in 21 patients [36.1%], and increased tumor size in 4 patients [7%]). Progression-free survival after GKRS at 3, 7, and 10 years was 100%, 98%, and 90%, respectively. The neurologic signs and symptoms were significantly improved after GKRS (14% versus 107%) compared with pretreated signs and symptoms (p < 0.0001). Five patients (8.8%) required additional treatment. Conclusion Recent follow-up revealed that GKRS offers a high rate of tumor control and preservation of neurologic functions in both new and recurrent patients with NFAs. Thus GKRS is an effective treatment option for recurrent and residual as well as newly diagnosed patients with NFAs.

Multisession Gamma Knife Radiosurgery for Orbital Apex Tumors

OBJECTIVE

This study was performed to analyze the outcome of multisession gamma knife radiosurgery (GKS) in benign tumors located at the orbital apex.

METHODS

Medical records of 23 patients who underwent multisession GKS for benign orbital apex tumors were reviewed retrospectively. Three patients were diagnosed by histology, and the other 20 patients were given the diagnoses on the basis of clinical and radiological findings. Diagnoses included cavernous hemangioma (8 cases), meningioma (8 cases), and schwannoma (7 cases). All patients were treated with 4 sessions of GKS with 12 hours of interval. Median marginal dose in each session was 5 Gy (range, 4.5-5.5 Gy) at the 50% isodose line (range, 50%-55%).

RESULTS

Mean clinical and imaging follow-up duration after treatment were 52.1 and 34.2 months, respectively. Tumor control was achieved in 22 patients (95.7%). Significant tumor shrinkage was observed in 17 patients (73.9%), and mean tumor volume reduction rate was 53.9%. Visual function was improved in 16 patients (69.6%) and stable in 4 patients (17.4%). Deterioration of visual acuity was reported by 3 patients (13.0%). Clinical and radiological response to multisession GKS was most excellent in cavernous hemangiomas with tumor control in all patients, and the mean tumor volume reduction rate was 68.3%.

CONCLUSIONS

Multisession GKS proved to be an effective and safe management strategy for benign orbital apex tumors. Response to treatment was different according to the pathology, and multisession GKS may be considered as the initial treatment of choice for specific pathology such as cavernous hemangioma.

CyberKnife multisession stereotactic radiosurgery and hypofractionated stereotactic radiotherapy for perioptic meningiomas: intermediate-term results and radiobiological considerations

Single fraction radiosurgery is conventionally precluded for lesions lying <2-3 mm of the anterior visual pathway because of the radiosensitivity of the optic nerve. We analyzed a series of 64 patients with “perioptic” meningiomas treated by CyberKnife multisession radiosurgery and hypofractionated stereotactic radiotherapy (hSRT). Between July 2007-May 2010, patients were treated using conventional multisession Cyberknife schemes (2–5 fractions) and results were retrospectively analyzed. A radiobiological model was then developed to estimate the best tumor control probability (TCP)/ normal tissue complication probability (NTCP) for these lesions. Resulting dose/fraction schemes were applied to patients treated between May 2010 and July 2014. Data were prospectively collected

Twenty-five patients were included in the retrospective part of the study. Median tumor volume was 4.95 cc; median dose was 23.0 Gy and median number of fraction was 5 (range 2–5). No patient had visual deterioration at mean follow-up of 60 ± 12 months. Tumor control was achieved in all cases. Thirty-nine patients were treated according the radiobiology model and results prospectively analyzed. Median tumor volume was 7.5 cc, median dose 25.0 Gy and mean number of fraction 5 (range 3–15). No patient had visual deterioration or tumor progression at mean follow-up of 17 ± 10 months.

Conventional multisession CyberKnife treatments (2–5 fractions) provided satisfactory results. Nonetheless, our estimation of TCP suggests the use of higher doses to grant long-term disease control. To achieve higher equivalent doses without significantly increasing the NTCP, we suggest the use of a greater number of fractions, moving to hSRT, in tumors in which the encasement of optic nerves is presumed.

Gamma knife surgery for patients with volumetric classification of nonfunctioning pituitary adenomas: a systematic review and meta-analysis

OBJECTIVE

The aim of this study was to scrutinize the literature to determine the efficacy and safety of gamma knife surgery (GKS) for the treatment of nonfunctioning pituitary adenomas (NFPAs) with volumetric classification.

METHODS

Electronic databases including MedLine, PubMed, and Cochrane Central were searched. The literature related to patients with NFPAs treated with GKS was collected. Eligible studies reported on the rate of tumor control (RTC), the rate of radiosurgery-induced optic neuropathy injury (RRIONI), the rate of radiosurgery-induced endocrinological deficits (RRIED), and other parameters.

RESULTS

A total of 17 studies met the criteria. based on the tumor volume, nfpas were divided into three groups: the RTC of group I (93 patients) with tumor volumes <2 ml was 99% (95% CI 96-100%), the RRIONI was 1% (95% CI 0-4%), and the RRIED was 1% (95% CI 0-4%). The RTC of group II (301 patients) with volumes from 2 to 4 ml was 96% (95% CI 92-99%), the RRIONI was 0 (95% CI 0-2%), and RRIED was 7% (95% CI 2-14%). The RTC of group III (531 patients) with volumes larger than 4 ml was 91% (95% CI 89-94%), the RRIONI was 2% (95% CI 0-5%), and the RRIED was 22% (95% CI 14-31%). There were significant differences in the RTC and in the RRIED among the three groups (P<0.001), indicating that there were higher RRIED and lower RTC with the increase of tumor volume.

CONCLUSIONS

NFPAs, according to tumor volume classification, need stratification for GKS treatment. GKS is the optimal choice for the treatment of group II NFPAs. Patients with residual tumor volumes of <4 ml will benefit most from GKS treatment.

Accuracy of CT and MRI for contouring the feline optic apparatus for radiation therapy planning

Consistency and accuracy in normal tissue contouring in radiotherapy planning is important for comparison of dosimetry and toxicity data between studies. The purpose of this study was to determine whether magnetic resonance imaging (MRI) improves the accuracy of optic apparatus contouring as compared with computed tomography (CT) in both normal and acromegalic cats, and to construct a reference contour of the feline optic apparatus. Both CT and MRI were performed on cadavers of four healthy cats, as well as on five radiotherapy patients with feline acromegaly. Contours of the optic apparatus were drawn for each imaging study. The volume, center of mass, and the degree of concordance and mismatch were determined for each, and compared with a reference standard. Precontrast CT was found to overestimate volume as compared with MRI in acromegalic cats; no other statistically significant differences were identified in the volume, concordance index or mismatch index values of normal or acromegalic cats. Contours derived from T2-wieghted MRI were subjectively considered to best match the reference standard. The caudal margin of the optic chiasm and the optic tracts were difficult to confidently contour regardless of which imaging modality and/or sequence was used. In conclusion, findings from the current study supported the use of a combination of CT and MR images and a priori knowledge of the shape of the optic apparatus to guide accurate contouring, especially where image contrast is not sufficient to clearly delineate the margins. Guidelines for feline optic apparatus contouring developed in this study can be used for future studies.

Intracystic irradiation for craniopharyngiomas

Data collected over a 36-year period were used to assess the value of stereotactically applied intracystic colloidal yttrium-90 (YTx) for the treatment of recurrent cystic craniopharyngiomas (CRF's). The article compares data from 95 YTx procedures carried out on 78 patients during the years 1975 and 2011, using a cumulative beta dose of 270 Gy aimed at the inner surface of the cyst wall. After YTx, the initial cyst volumes decreased an average of 74.7 %. In 54 patients, the volume reduction exceeded 80 %. In 32 patients, the cyst disappeared completely within one year. The mean survival rate following YTx was 7.5 years (range 0.7-31 years). The survival rates at 5, 10, 15, 20, 25, and 30 years were 56, 29, 15, 8, 3, and 1 %, respectively. Late complications of YTx were related to the anatomical location of the cyst, either presellar or retrosellar. A presellar, that is, prechiasmatic/suprasellar localization resulted in neuro-ophthalmological complications in 5.1 % of the cases, while internal carotid artery injury accounted for 1.4 % of the complications. The treatment of retrosellar (retrochiasmatic, suprasellar) tumors may cause hypothalamic, fornix, or pontomesencephalothalamic damage, from untoward radiation to the so-called perforating arteries. This complication occurred in 5.2 % of the cases. In the multimodality management of craniopharyngioma cysts, intracavity YTx irradiation is a valuable treatment alternative despite sporadic complications arising in some surgical cases. The formula for the calculation of the dynamics of reduction of CRF's following yttrium-90 colloid brachytherapy was supported by correlating the collected data. The focus was on our minimally invasive YTx following multiple surgeries of cystic CRFs.

Benign orbital apex tumors treated with multisession gamma knife radiosurgery

OBJECTIVE

The orbital apex is an important anatomic landmark that hosts numerous critical neurovascular structures. Tumor resection performed at this complex region poses a therapeutic challenge to orbital surgeons and often is associated with significant visual morbidity. This article reports the efficacy and safety of multisession gamma knife radiosurgery (GKRS) in benign, well-circumscribed tumors located at the orbital apex.

DESIGN

Retrospective interventional case series.

PARTICIPANTS

Five patients with visual disturbances resulting from a benign, well-circumscribed orbital apex tumor (3 cases of cavernous hemangioma and 2 cases of schwannoma).

METHODS

Each patient treated with GKRS with a total radiation dose of 20 Gy in 4 sessions (5 Gy in each session with an isodose line of 50%) delivered to the tumor margin.

MAIN OUTCOME MEASURES

Best-corrected visual acuity, visual field changes, orbital imaging, tumor growth control, and side effects of radiation.

RESULTS

All patients demonstrated improvement in visual acuity, pupillary responses, color vision, and visual field. Tumor shrinkage was observed in all patients and remained stable until the last follow-up. No adverse events were noted during or after the radiosurgery. None of the patients experienced any radiation-related ocular morbidity.

CONCLUSIONS

From this experience, multisession GKRS seems to be an effective management strategy to treat solitary, benign, well-circumscribed orbital apex tumors.

Gamma Knife surgery for patients with nonfunctioning pituitary macroadenomas: predictors of tumor control, neurological deficits, and hypopituitarism

Object

Nonfunctioning pituitary macroadenomas often recur after microsurgery and thereby require further treatment. Gamma Knife surgery (GKS) has been used to treat recurrent adenomas. In this study, the authors evaluated outcomes following GKS of nonfunctioning pituitary macroadenomas and assessed predictors of tumor control, neurological deficits, and delayed hypopituitarism.

Methods

Between June 1989 and March 2010, 140 consecutive patients with nonfunctioning pituitary macroadenomas were treated using GKS at the University of Virginia. The median patient age was 51 years (range 21–82 years), and 56% of patients were male. Mean tumor volume was 5.6 cm3 (range 0.6–35 cm3). Thirteen patients were treated with GKS as primary therapy, and 127 had undergone at least 1 open resection prior to GKS. Ninety-three patients had a history of hormone therapy prior to GKS. The mean maximal dose of GKS was 38.6 Gy (range 10–70 Gy), the mean marginal dose was 18 Gy (range 5–25 Gy), and the mean number of isocenters was 9.8 (range 1–26). Follow-up evaluations were performed in all 140 patients, ranging from 0.5 to 17 years (mean 5 years, median 4.2 years).

Results

Tumor volume remained stable or decreased in 113 (90%) of 125 patients with available follow-up imaging. Kaplan-Meier analysis demonstrated radiographic progression free survival at 2, 5, 8, and 10 years to be 98%, 97%, 91%, and 87%, respectively. In multivariate analysis, a tumor volume greater than 5 cm3 (hazard ratio = 5.0, 95% CI 1.5–17.2; p = 0.023) was the only factor predictive of tumor growth. The median time to tumor progression was 14.5 years. Delayed hypopituitarism occurred in 30.3% of patients. No factor was predictive of post-GKS hypopituitarism. A new or worsening cranial nerve deficit occurred in 16 (13.7%) of 117 patients. Visual decline was the most common neurological deficit (12.8%), and all patients experiencing visual decline had evidence of tumor progression. In multivariate analysis, a tumor volume greater than 5 cm3 (OR = 3.7, 95% CI 1.2–11.7; p = 0.025) and pre-GKS hypopituitarism (OR = 7.5, 95% CI 1.1–60.8; p = 0.05) were predictive of a new or worsened neurological deficit.

Conclusions

In patients with nonfunctioning pituitary macroadenomas, GKS confers a high rate of tumor control and a low rate of neurological deficits. The most common complication following GKS is delayed hypopituitarism, and this occurs in a minority of patients.

Stereotactic radiosurgery for WHO grade I meningiomas

Meningiomas represent a common intracranial tumor in the adult population. Although extirpation to achieve a gross total resection or at least decrease mass effect has been the mainstay of treatment, stereotactic radiosurgery has come to play an increasingly important role in the management of patients with meningiomas. Radiosurgery utilizes highly focused, beams of ionizing radiation to inactivate tumor cells. Image guidance and a steep dose fall off are critical features of this approach. The radiobiology of radiosurgery differs in certain advantageous ways from conventional radiotherapy. Radiosurgery initially was utilized to treat recurrent or residual skull base meningiomas. As success was observed in this setting, radiosurgery has gradually expanded its role so as to treat convexity meningiomas; it is also used as an upfront treatment for patients for whom clinical and neuro-imaging findings are consistent with a meningioma. Most large series demonstrate tumor control rates for patients with grade I meningiomas in excess of 85%. Neurological function is generally preserved or improved for patients with meningiomas. However, complications can occur. Longitudinal follow-up including neurologic and radiologic assessment is required. Single and multisession stereotactic radiosurgery will likely play an expanded role in the treatment of patients with meningiomas.

Gamma knife surgery of meningiomas involving the cavernous sinus: long-term follow-up of 100 patients

OBJECTIVE

Resection of meningiomas involving the cavernous sinus often is incomplete and associated with considerable morbidity. As a result, an increasing number of patients with such tumors have been treated with gamma knife surgery (GKS). However, few studies have investigated the long-term outcome for this group of patients.

METHODS

100 patients (23 male/77 female) with meningiomas involving the cavernous sinus received GKS at the Department of Neurosurgery at Haukeland University Hospital, Bergen, Norway, between November 1988 and July 2006. They were followed for a mean of 82.0 (range, 0-243) months. Only 2 patients were lost to long-term follow-up. Sixty patients underwent craniotomy before radiosurgery, whereas radiosurgery was the primary treatment for 40 patients.

RESULTS

Tumor growth control was achieved in 84.0% of patients. Twelve patients required re-treatment: craniotomy (7), radiosurgery (1), or both (4). Three out of 5 patients with repeated radiosurgery demonstrated secondary tumor growth control. Excluding atypical meningiomas, the growth control rate was 90.4%. The 1-, 5-, and 10-year actuarial tumor growth control rates are 98.9%, 94.2%, and 91.6%, respectively. Treatment failure was preceded by clinical symptoms in 14 of 15 patients. Most tumor growths appeared within 2.5 years. Only one third grew later (range, 6-20 yr). The complication rate was 6.0%: optic neuropathy (2), pituitary dysfunction (3), worsening of diplopia (1), and radiation edema (1). Mortality was 0. At last follow-up, 88.0% were able to live independent lives.

CONCLUSION

GKS gives long-term growth control and has a low complication rate. Most tumor growths manifest within 3 years following treatment. However, some appear late, emphasizing the need for long-term follow-up.

Tolerance of the optic apparatus in single-fraction irradiation using stereotactic radiosurgery: evaluation in 100 patients with craniopharyngioma

OBJECTIVE

To determine the limiting dose to the optic apparatus in single-fraction irradiation in patients with craniopharyngioma treated with gamma knife radiosurgery (GKRS).

METHODS

One hundred patients with 109 craniopharyngiomas treated with GKRS were evaluated with a median follow-up period of 68 months. Tumor volume varied from 0.1 to 36.0 (median, 3.3) cm. Marginal doses varied from 10 to 18 (median, 11.4) Gy. Maximum dose to any part of the optic apparatus varied from 2 to 18 (median, 10) Gy.

RESULTS

The actuarial 5- and 10-year overall rates of survival of tumor progression after GKRS were 93% and 88%, respectively. Similarly, the actuarial 5- and 10-year progression-free survival rates were 62% and 52%, respectively. Among 94 patients in whom visual function was evaluable after GKRS, only 3 patients developed radiation-induced optic neuropathy, indicating an overall Kaplan-Meier radiation-induced optic neuropathy rate of 5%. Of these patients, 2 received 15 Gy or greater to the optic apparatus. Another patient who received 8 Gy or less had undergone previous fractionated radiation therapy with a biologically effective dose of 60 Gy.

CONCLUSION

The optic apparatus seems to be more tolerant of irradiation than previously thought. Careful dose planning is essential, particularly in patients who underwent prior external beam radiation therapy.

Stereotactic radiosurgery for pituitary adenomas: a comprehensive review of indications, techniques and long-term results using the Gamma Knife

OBJECT

This study reviews the long-term clinical results of stereotactic radiosurgery in the treatment of pituitary adenoma patients.

METHODS

We reviewed the outcomes of 298 patients who underwent Gamma Knife radiosurgery for recurrent or residual pituitary adenomas. These results are compared to other contemporary radiosurgical series.

RESULTS

Pituitary tumors are well-suited for radiosurgery, since radiation can be focused on a well circumscribed region, while adjacent neural structures in the suprasellar and parasellar regions are spared. The overall rate of volume reduction following stereotactic radiosurgery is 85% for non-secretory adenomas that are followed for more than 1-year. The rates of hormonal normalization in patients with hypersecretory adenomas can vary considerably, and tends to be higher in patients with Cushing's Disease and acromegaly (remission rate of approximately 53% and 54%, respectively) when compared with patients who have prolactinomas (24% remission) and Nelson's syndrome (29%) remission. Advances in dose delivery and modulation of adenoma cells at the time of radiosurgery may further improve results.

CONCLUSIONS

Although the effectiveness of radiosurgery varies considerably depending on the adenoma histopathology, volume, and radiation dose, most studies indicate that radiosurgery when combined with microsurgery is effective in controlling pituitary adenoma growth and hormone hypersecretion. Long-term follow-up is essential to determine the rate of endocrinopathy, visual dysfunction, hormonal recurrence, and adenoma volume control.

Neuroophthalmological evaluation after Gamma Knife surgery for cavernous sinus meningiomas

Object

Treatment options for patients with cavernous sinus meningiomas (CSMs) include microsurgical tumor resection, radiotherapy, and radiosurgery. Gamma Knife surgery (GKS) is increasingly being used because it is associated with lower mortality and morbidity rates than microsurgery. The purpose of this study was to assess the role of GKS in the treatment of CSM and to thoroughly analyze the clinical response to GKS.

Methods

Between January 2001 and December 2005, 123 patients (25 men and 98 women; mean age 62.6 ± 11 years, range 31–86 years) who underwent treatment for CSMs were included in this study. Of these, 41 patients underwent microsurgery before GKS, whereas the remaining 82 had GKS as a first-line therapy after a diagnosis was made based on magnetic resonance imaging findings. Dysfunction in cranial nerves (CNs) II, III, IV, V, and VI was noted in 74 patients at the time of GKS. The mean tumor volume was 7.99 cm3 (0.7–30.5 cm3). The mean prescription dose to the tumor margin was 13.8 ± 1.1 Gy (range 10–20 Gy).

Results

The overall tumor control rate was 98.4% with a median follow-up of 36 months. The actuarial tumor control rate at 5 years was 90.5%. A reduction in tumor volume was observed in 53 patients (43.1%), whereas in 68 patients (55.3%) no volumetric variation was recorded. Of the 74 patients who presented with CN deficits, improvement was noted in 23 (31.1%).

Conclusions

Gamma Knife surgery is a useful treatment for CSM both as a first- or second-line therapy. It is a safe and effective treatment for tumors located close to the optic pathways.

Boron distribution in the normal rat brain after intravenous injection of boronophenylalanine-fructose

Boron neutron capture therapy (BNCT) is an experimental form of radiation therapy for malignant brain tumors and peripheral melanoma. The micro-distribution of the boron compound is critical to determine the radiation effects for both tumors and normal tissue. In the current dose calculation of BNCT, normal brain tissue is considered to have a homogeneous boron concentration. The purpose of this study was to examine the structure-specific boron concentration in normal rat neural tissue. At 10, 30 and 60 min after intravenous injection of 300 mg/kg boronophenylalanine-fructose to 10-week-old CD Fisher rats, neural tissue and blood were collected. Various neural structures were anatomically and histologically identified and specific boron concentrations were analyzed using high-resolution quantitative autoradiography. At 60 min after the injection, only the pituitary gland showed a higher boron concentration than that in blood, with the former being threefold higher. All other neural structures showed lower boron concentrations than that in blood. The present study thus demonstrated an extremely high boron concentration in the pituitary gland following intravenous injection of boronophenylalanine-fructose. In clinical trials of BNCT using an epithermal neutron beam, the radiation dose to the pituitary gland should be carefully evaluated.

LONG-TERM RESULTS AND LATE COMPLICATIONS AFTER INTRACAVITARY YTTRIUM-90 COLLOID IRRADIATION OF RECURRENT CYSTIC CRANIOPHARYNGIOMAS

OBJECTIVE

Data were analyzed to assess the value of stereotactically applied intracystic colloidal yttrium-90 (YTx) for the treatment of recurrent cystic craniopharyngiomas during a 30-year period.

METHODS

This article compares data from 73 YTx procedures in 60 patients between 1975 and 2006. The cumulative beta dose aimed at the inner surface of the cyst wall was 300 Gy.

RESULTS

After YTx, the initial cyst volumes decreased an average of 79%. In 47, the reduction was more than 80%; in 27 of them, the cyst disappeared completely within 1 year. The mean survival after YTx was 9.4 years (range, 0.7–30 yr). Actuarial survival rates at 5, 10, 15, 20, 25, and 30 years were 81, 61, 45, 18, 2, and 0%, respectively. Late complications of YTx were related to the anatomic localization of the cyst, either presellar and retrosellar, e.g., a presellar (prechiasmatic/suprasellar) localization caused neuro-ophthalmological complications in 5.8% and internal carotid artery injury in 1.6%. The treatment of retrosellar (retrochiasmatic, suprasellar) tumors occasionally induced hypothalamic and/or pontomesencephalothalamic damage obviously by untoward radiation to the so-called perforating arteries. This occurred in 3.2% of these latter patients.

CONCLUSION

Despite sporadic complications, intracavitary YTx irradiation is a valuable treatment alternative for craniopharyngioma cysts, sometimes as part of a multimodality management in these tumors, especially in precarious surgical cases.

Gamma Knife surgery for Cushing's disease

Object

In this study the authors address the efficacy and safety of Gamma Knife surgery (GKS) in patients with adrenocorticotropic hormone–secreting pituitary adenomas.

Methods

A review of data collected from a prospective GKS database between January 1990 and March 2005 was performed in patients with Cushing's disease. All but one patient underwent resection for a pituitary tumor, without achieving remission. Successful endocrine outcome after GKS was defined as a normal 24-hour urinary free cortisol (UFC) concentration posttreatment after a minimum of 1 year of follow up. Patient records were also evaluated for changes in tumor volume, development of new hormone deficiencies, visual acuity, cranial nerve neuropathies, and radiation-induced imaging changes. Ninety evaluable patients had undergone GKS, with a mean endocrine follow-up duration of 45 months (range 12–132 months). The mean dose to the tumor margin was 23 Gy (median 25 Gy).

Normal 24-hour UFC levels were achieved in 49 patients (54%), with an average time of 13 months after treatment (range 2–67 months). In the 49 patients in whom a tumor was visible on the planning magnetic resonance (MR) image, a decrease in tumor size occurred in 39 (80%), in seven patients there was no change in size, and tumor growth occurred in three patients. Ten patients (20%) experienced a relapse of Cushing's disease after initial remission; the mean time to recurrence was 27 months (range 6–60 months). Seven of these patients underwent repeated GKS, with three patients achieving a second remission. New hormone deficiencies developed in 20 patients (22%), with hypothyroidism being the most common endocrinopathy after GKS. Five patients experienced new visual deficits or third, fourth, or sixth cranial nerve deficits; two of these patients had undergone prior conventional fractionated radiation therapy, and four of them had received previous GKS. Radiation-induced changes were observed on MR images in three patients; one had symptoms attributable to these changes.

Conclusions

Gamma Knife surgery is an effective treatment for persistent Cushing's disease. Adenomas with cavernous sinus invasion that are not amenable to resection are treatable with the Gamma Knife. A second GKS treatment appears to increase the risk of cranial nerve damage. These results demonstrate the value of combining two neurosurgical treatment modalities—microsurgical resection and GKS—in the management of pituitary adenomas.

Visual field preservation after multisession cyberknife radiosurgery for perioptic lesions

OBJECTIVE

The restricted radiation tolerance of the anterior visual pathways represents a unique challenge for ablating adjacent lesions with single-session radiosurgery. Although preliminary studies have recently demonstrated that multisession radiosurgery for selected perioptic tumors is both safe and effective, the number of patients in these clinical series was modest and the length of follow-up limited. The current retrospective study is intended to help address these shortcomings.

METHODS

Forty-nine consecutive patients with meningioma (n = 27), pituitary adenoma (n = 19), craniopharyngioma (n = 2), or mixed germ cell tumor (n = 1) situated within 2 mm of a "short segment" of the optic apparatus underwent multisession image-guided radiosurgery at Stanford University Medical Center. Thirty-nine of these patients had previous subtotal surgical resection, and six had previously been treated with conventional fractionated radiotherapy (6). CyberKnife radiosurgery was delivered in two to five sessions to an average tumor volume of 7.7 cm3 and a cumulative average marginal dose of 20.3 Gy. Formal visual testing and clinical examinations were performed before treatment and at follow-up intervals beginning at 6 months.

RESULTS

After a mean visual field follow-up of 49 months (range, 6-96 mo), vision was unchanged postradiosurgery in 38 patients, improved in eight (16%), and worse in three (6%). In each instance, visual deterioration was accompanied by tumor progression that ultimately resulted in patient death. However, one of these patients, who had a multiply recurrent adrenocorticotropic hormone-secreting pituitary adenoma, initially experienced early visual loss without significant tumor progression after both a previous course of radiotherapy and three separate sessions of radiosurgery. After a mean magnetic resonance imaging follow-up period of 46 months, tumor volume was stable or smaller in all other cases. Two patients died of unrelated nonbrain causes.

CONCLUSION

Multisession radiosurgery resulted in high rates of tumor control and preservation of visual function in this group of perioptic tumors. Ninety-four percent of patients retained or improved preradiosurgical vision. This intermediate-term experience reinforces the findings from earlier studies that suggested that multisession radiosurgery can be a safe and effective alternative to either surgery or fractionated radiotherapy for selected lesions immediately adjacent to short segments of the optic apparatus.

Evaluation of fractionated radiotherapy and gamma knife radiosurgery in cavernous sinus meningiomas: treatment strategy

OBJECTIVE

To investigate the respective role of fractionated radiotherapy (FR) and gamma knife stereotactic (GKS) radiosurgery in cavernous sinus meningioma (CSM) treatment.

METHODS

The authors report the long-term follow-up of two populations of patients harboring CSMs treated either by FR (Group I, 38 patients) or GKS radiosurgery (Group II, 36 patients). There were 31 females with a mean age of 53 years in Group I and 29 females with a mean age of 51.2 years in Group II. In 20 patients (Group I) and 13 patients (Group II), FR and GKS radiosurgery were performed as an adjuvant treatment. In 18 patients (Group I) and in 23 patients (Group II), FR and GKS radiosurgery were performed as first line treatment. In our early experience with GKS radiosurgery (1992, date of gamma knife availability in the department), patients with tumors greater than 3 cm, showing close relationship with the optic apparatus (<3 mm) or skull base dural spreading, were treated by FR. Secondarily, with the advent of new devices and our growing experience, these criteria have evolved.

RESULTS

The median follow-up period was 88.6 months (range, 42-168 mo) for Group I and 63.6 months (range, 48-92 mo) for Group II. According to Sekhar's classification, 26 (68.4%) patients were Grade III to IV in Group I and 10 (27.8%) patients in Group II (P < 0.05); 23 (60.5%) patients had extensive lesions in Group I and 7 (19.4%) patients in Group II (P < 0.05). Mean tumor volume was 13.5 cm in Group I and 5.2 cm in Group II (P < 0.05). Actuarial progression-free survival was 94.7% and 94.4% in Group I and II, respectively. Clinically, improvement was seen for 24 (63.2%) patients in Group I and for 21 (53.8%) patients in Group II (P > 0.05). Radiologically, 11 (29%, Group I) patients and 19 (Group II, 52.7%) patients showed tumor shrinkage (P = 0.04). Transient morbidity was 10.5% in Group I and 2.8% in Group II. Permanent morbidity was 2.6% in Group I and 0% in Group II.

CONCLUSION

FR and GKS radiosurgery are safe and efficient techniques in treatment of CSMs, affording comparable satisfactory long-term tumor control. However, GKS radiosurgery provides better radiological response, is far more convenient, and fits into most patients lives much better than FR. Therefore, in the authors' opinion, GKS radiosurgery should be advocated in first intention for patients with CSMs, whereas conventional radiotherapy should be reserved for cases that are not amenable to this technique, thus making these two therapeutic modalities not alternative but complementary tools in CS meningioma treatment strategy.

Imaging of neoplasms of the paranasal sinuses

The assessment of sinonasal malignancies requires a multidisciplinary team approach.Advances in pretherapeutic imaging have significantly contributed to the managementof sinonasal tumors. CT and MR imaging play complementary roles in the assess-mentand staging of these malignancies by determining the presence or absence of exten-sionof disease into the skull base and its foramina, the orbit, and the intracranial compartment.

Stereotactic radiosurgery for Cushing disease

The most common cause of Cushing syndrome is Cushing disease, in which hypercortisolism is produced by a functional adrenocorticotropic hormone–producing adenoma of the anterior pituitary gland. The common therapies available include microsurgical resection, conventional fractionated radiotherapy, and stereotactic radiosurgery (SRS). In this article the authors review the indications, results, and complications associated with SRS in the treatment of Cushing disease.

In as many as 90% of patients SRS results in disease remission, which is defined as a normal 24-hour urinary free cortisol level and a normal or subnormal morning serum cortisol level. Although in most patients who are subsequently cured a marked decrease in the serum cortisol level is demonstrated within 3 months after treatment, a biochemical cure may be delayed up to 3 years in some cases. Complications following SRS for pituitary adenomas are uncommon, particularly in patients with microadenomas, which are most commonly seen in Cushing disease. The most common complication is hypopituitarism, which occurs in up to 50% of patients with a mean latency period of 5 years. Radiation-induced optic neuropathy has been reported in less than 2% of cases and induction of a secondary neoplasm in less than 1% of cases.

For patients with Cushing disease, the rate of endocrinological cure following SRS appears to be similar to that attained using microsurgical resection. In contrast to surgery, SRS has the benefit of being noninvasive and associated with a very low incidence of diabetes insipidus, although hypopituitarism may be more common with SRS. With continued follow-up patient reviews and additional experience with SRS, it may become possible to make more definitive statements regarding SRS as the initial treatment for patients with Cushing disease.

Imaging of neoplasms of the paranasal sinuses

The assessment of sinonasal malignancies requires a multidisciplinary team approach. Advances in pretherapeutic imaging have significantly contributed to the management of sinonasal tumors. CT and MR imaging play complementary roles in the assessment and staging of these malignancies by determining the presence or absence of extension of disease into the skull base and its foramina, the orbit, and the intracranial compartment.

Preservation of visual fields after peri-sellar gamma-knife radiosurgery

Radiosurgical treatment of pituitary and peri-sellar tumors has become an increasingly utilized modality as an alternative to conventional radiotherapy and surgery. Such radiosurgery results in a relatively high dose of radiation to the optic chiasm. The clinical data establishing safe single-fraction doses to the chiasm is immature, although taken together previous literature suggests a recommended maximal dose of 8 Gy. Optic neuropathy, when it occurs, tends to take place within 2 years of treatment. We evaluated the visual fields of 20 sequential patients that received significant doses to the optic chiasm by Gamma-knife radiosurgery. There were 17 cases of pituitary adenoma and 3 cases of meningioma, and two patients refused follow-up testing. Preoperative visual field and cranial nerve examinations were done prior to radiosurgery and in follow-up, with a median follow-up of 24 months. There were no cases of quantitative visual field deficit induced by treatment. No patients developed symptomatic visual deterioration. Radiat. Oncol. Invest. 90:343-350, 2000. 2000 Wiley-Liss, Inc.

Fractionated stereotactic radiotherapy (FSRT) for optic glioma

PURPOSE

To determine efficacy and toxicity of fractionated stereotactic radiotherapy (FSRT) in patients with optic glioma.

METHODS AND MATERIALS

Ten patients suffering from optic glioma were treated by FSRT between December 1990 and December 1995 at the German Cancer Research Center (DKFZ) in Heidelberg. Eight patients were treated for progressive recurrent tumor following partial tumor resection and 2 patients were treated postoperatively. Dose distributions were calculated by a 3D treatment planning system (Voxelplan, Heidelberg). Patients were treated with a noninvasive repeatable stereotactic fixation system using a manually driven midsize multileaf collimator attached to a linear accelerator. We applied a median prescribed total dose to the isocenter of 52.4 Gy with a median daily fraction size of 1.8 Gy.

RESULTS

All patients treated by definitive radiotherapy remained free from local tumor progression during the follow-up period (range 12-72 months) except the 1 patient treated for recurrence after previous radiotherapy. A complete remission was achieved in 3 patients with subsequent improvement of visual acuity. None of the patients with locally controlled tumor experienced any further impairment of vision. One patient developed new ACTH deficiency. No other clinically significant late effects attributable to radiotherapy were observed.

CONCLUSION

FSRT permits treatment of optic glioma with excellent tumor control and without clinically relevant morbidity. Compared to conventional techniques there is the potential of sparing the pituitary gland in chiasmatic lesions.

Dose-response tolerance of the visual pathways and cranial nerves of the cavernous sinus to stereotactic radiosurgery

As the number of patients treated with stereotactic radiosurgery increases, it becomes particularly important to define with precision adverse effects on distinct structures of the nervous system.

OBJECT

This study was designed to assess the dose-response tolerance of the visual pathways and cranial nerves after exposure of the cavernous sinus to radiation.

METHODS

A total of 66 sites in the visual system and 210 cranial nerves of the middle cranial fossa were investigated in 50 patients who had undergone gamma knife treatment for benign skull base tumors. The mean follow-up period was 40 months (range 24-60 months). Follow-up examinations consisted of neurological, neuroradiological, and neuroophthalmological evaluations. The actuarial incidence of optic neuropathy was zero for patients who received a radiation dose of less than 10 Gy, 26.7% for patients receiving a dose in the range of 10 to less than 15 Gy, and 77.8% for those who received doses of 15 Gy or more (p < 0.0001). Previously impaired vision improved in 25.8% and was unchanged in 51.5% of patients. No sign of neuropathy was seen in patients whose cranial nerves of the cavernous sinus received radiation doses of between 5 and 30 Gy. Because tumor control appeared to have been achieved in 98% of the patients, the deterioration in visual function cannot be attributed to tumor progression.

CONCLUSIONS

The structures of the visual pathways (the optic nerve, chiasm, and tract) exhibit a much higher sensitivity to single-fraction radiation than other cranial nerves, and their particular dose-response characteristics can be defined. In contrast, the oculomotor and trigeminal nerves have a much higher dose tolerance.

Radiation optic neuropathy after stereotactic radiosurgery

PURPOSE

The purpose of the study is to report the occurrence of optic neuropathy after stereotactic radiosurgery for perichiasmal tumors.

METHODS

Records of four patients with visual deterioration after stereotactic radiosurgery were reviewed, including clinical findings, neuroimaging results, and treatment methods.

RESULTS

Optic neuropathy developed 7 to 30 months after gamma knife radiosurgery. All patients experienced an abrupt change in visual function. Clinical findings indicated anterior visual pathway involvement. Patterns of field loss included nerve fiber bundle and homonymous hemianopic defects. Gadolinium-enhanced magnetic resonance imaging (MRI) showed swelling and enhancement of the affected portion of the visual apparatus in three patients. Systemic corticosteroids were administered in all patients and one partially recovered. One patient also received hyperbaric oxygen without improvement.

CONCLUSIONS

Although rare, optic neuropathy may follow radiosurgery to lesions near the visual pathways. Careful dose planning guided by MRI with restriction of the maximal dose to the visual pathways to less than 8 Gy will likely reduce the incidence of this complication.