Gamma Knife Radiosurgery for Third Ventricular Colloid Cysts: A Retrospective Study.

INTRODUCTION: Colloid cysts often occur in the third ventricle, and they are considered benign, slowly growing lesions. They commonly present with symptoms of intracranial hypertension and rarely sudden death due to acute hydrocephalus. The management options include cerebrospinal fluid diversion procedure by shunt, endoscopic or transcranial surgical excision, and stereotactic aspiration. Complications associated with excisional procedures make them undesirable to some patients. Stereotactic radiosurgery has emerged as a noninvasive less risky treatment option. To date, there is no clinical series in the literature reporting on this treatment modality. The aim of the study was to determine the efficacy and safety of gamma knife (GK) radiosurgery in the treatment of third ventricular colloid cysts. METHODS: This is a retrospective study involving 13 patients with third ventricular colloid cysts who underwent GK radiosurgery. GK radiosurgery was used as a primary treatment in all the patients. The median prescription dose was 12 Gy (11-12 Gy). The cyst volumes ranged from 0.2 to 10 cc (median 1.6 cc). RESULTS: The median follow-up was 50 months (18-108 months). Cyst control was achieved in 100% of the patients. Complete or partial response was observed in 12 patients (92%). Eight patients (62%) had hydrocephalus on imaging at the initial diagnosis. Seven of these patients had VP shunt insertion before GK. One patient required shunt insertion after GK. CONCLUSION: GK for third ventricular colloid cysts is a promising treatment, regarding its efficacy and safety, to be added to other treatment options. A longer follow-up is required to confirm long-term control.

Single-session stereotactic radiosurgery for large perioptic meningiomas.

OBJECTIVE: Meningiomas close to the optic pathway are commonly candidates for microsurgical decompression, more so if they are large perioptic meningiomas. However, microsurgery itself imposes risk to vision, and the larger the tumor, the more the risk and the lower the possibility of postoperative visual recovery. Fractionated stereotactic radiotherapy is usually reserved for such cases. The purpose of this study was to assess the long-term efficacy and safety of single-session stereotactic radiosurgery (SRS) for large (≥ 10 cm3) perioptic intracranial benign meningiomas. METHODS: This retrospective study included 175 patients with large perioptic benign meningiomas (≥ 10 cm3) who were treated by single-session SRS. Perioptic meningiomas were defined as meningiomas touching, compressing, or within 3 mm of the optic pathway. The median tumor volume was 15 cm3 (range 10-57.3 cm3, IQR 8.4 cm3). The median prescription dose was 12 Gy (range 9-14 Gy, IQR 1 Gy). RESULTS: The median follow-up period was 72 months (range 13-217 months, IQR 65 months). The tumor control rate was 92%. The progression-free survival rates at 5 and 10 years were 97% and 80%, respectively. Favorable (better/stable) visual outcome was reported in 169 patients (97%) and unfavorable (worse) outcome in 6 patients (3%). Temporary adverse radiation effects were observed in 21 patients (12%), but only 7 patients (4%) were symptomatic. Sixty-three patients had a blind/nonuseful eye according to the pretreatment visual field examination. Visual improvement was observed in the blind/nonuseful eye in 17 patients (27%), while vision remained unchanged in 46 patients (73%). Ocular nerve palsy improved in 36 patients (61%). Tumor shrinkage was not a prerequisite for cranial nerve improvement. CONCLUSIONS: SRS provides an effective and safe treatment option for large perioptic meningiomas.

Single-Session Stereotactic Radiosurgery for Large Benign Meningiomas: Medium-to Long-Term Results.

BACKGROUND: The use of stereotactic radiosurgery for the treatment of intracranial meningiomas has been established as an effective and safe treatment modality. Larger meningiomas typically are managed by surgery followed by radiosurgery. Treatment of large meningiomas (usually defined as >10 cc) by stereotactic radiosurgery has been investigated in some recent reports, either by single-session, volume-staged, or the hypofractionation technique. We sought to assess the long-term efficacy and safety of single-session stereotactic radiosurgery for large (10 cc or more) intracranial benign meningiomas. PATIENTS AND METHODS: In this retrospective study, we included 273 patients with large benign meningiomas (≥10 cc) who were treated by single-session SRS and followed up for more than 2 years. Tumors were in a basal location in 228 patients (84%). There were 161 tumors (59%) in the perioptic location. The median tumor volume was 15.5 (10-57.3 cc [interquartile range {IQR} 12.3 cc]). The median prescription dose was 12 Gy (9-15 Gy [IQR 1 Gy]). RESULTS: The median follow-up period was 6.1 years (2-18 years [IQR 5.5 years]). The tumor control rate was 90%. The progression-free survival at 5 and 10 years was 96% and 81%, respectively, for the whole cohort. Among 161 patients with perioptic meningiomas, favorable (better/stable) visual outcome was reported in 155 patients (96%) and unfavorable (worse) outcome in 6 patients (4%). Temporary adverse radiation effects were observed in 41 patients (15%) but only 16 (6%) were symptomatic. CONCLUSIONS: Stereotactic radiosurgery provides an effective and safe treatment option for large meningiomas.

Volume-Staged Gamma Knife Radiosurgery for Large Brain Arteriovenous Malformation.

OBJECTIVE: Large brain arteriovenous malformations (AVMs) pose a management dilemma because of the limited success of any single treatment modality by itself. Surgery alone is associated with significant morbidity and mortality. Similarly, embolization alone has limited efficacy. Volume-staged Gamma Knife radiosurgery (VSGR) has been developed for the treatment of large AVMs to increase the efficacy and improve safety of treatment of these lesions. The aim of this study was to assess the efficacy and safety of VSGR technique for the treatment of large brain AVMs. METHODS: The study included patients treated by VSGR between May 2009 and July 2015. All patients had large AVMs (>10 mL). There were 29 patients. RESULTS: Twenty-four patients completed radiographic follow-up, with 15 obliteration cases (62.5%). A total of 56 sessions were performed. The mean AVM volume was 16 mL (range, 10.1-29.3 mL). The mean prescription dose was 18 Gy (range, 14-22 Gy). The mean follow-up duration was 43 months (range, 21-73 months). One patient died during follow-up of an unrelated cause. Two patients had hemorrhage during follow-up. Symptomatic edema developed in 5 patients (17%). The factors affecting obliteration were smaller total volume, higher dose/stage, nondeep location, compact AVM, AVM score <3, >18 Gy dose, and <15 mL total volume. The factors affecting symptomatic edema were smaller total volume and shorter time between first and last sessions (P = 0.012). T2 image changes were affected by Spetzler-Martin grade ≥3 (P = 0.013) and AVM score ≥3 (P = 0.014). CONCLUSIONS: VSGR provides an effective and safe treatment option for large brain AVMs. Smaller AVM volume is associated with higher obliteration rate.

Hearing preservation after Gamma Knife radiosurgery for cerebellopontine angle meningiomas.

OBJECTIVEThe objective of this study was to assess hearing function after Gamma Knife treatment of cerebellopontine angle (CPA) meningiomas and assess factors affecting hearing outcome. Additionally, the authors opted to compare these results with those after Gamma Knife treatment of vestibular schwannomas (VSs), because most of the information on hearing outcome after stereotactic radiosurgery (SRS) comes from reports on VS treatment. Hearing preservation, to the best of the authors' knowledge, has never been separately addressed in studies involving Gamma Knife radiosurgery (GKRS) for CPA meningiomas.METHODSThis study included all patients who underwent a single session of GKRS between 2002 and 2014. The patients were divided into two groups. Group A included 66 patients with CPA meningiomas with serviceable hearing and tumor extension into the region centered on the internal auditory meatus. Group B included 144 patients with VSs with serviceable hearing. All patients had serviceable hearing before treatment (Gardner-Robertson [GR] Grades I and II). The median prescription dose was 12 Gy (range 10-12 Gy) in both groups. The median follow-up of groups A and B was 42 months (range 6-149 months) and 49 months (range 6-149 months), respectively.RESULTSAt the last follow-up, the tumor control rate was 97% and 94% in groups A and B, respectively. Hearing preservation was defined as maintained serviceable hearing according to GR hearing score. The hearing preservation rate was 98% and 66% and the 7-year actuarial serviceable hearing preservation rate was 75% and 56%, respectively, between both groups. In group A, the median maximum cochlear dose in the patients with stable and worsened hearing grade was 6.3 Gy and 5.5 Gy, respectively. In group B, factors affecting hearing preservation were cochlear dose ≤ 7 Gy, follow-up duration, and tumor control. The only determinant of hearing preservation between both groups was tumor type.CONCLUSIONSGKRS for CPA meningiomas provides excellent hearing preservation in addition to high tumor control rate. Hearing outcome is better with CPA meningiomas than with VSs. Further long-term prospective studies on determinants of hearing outcome after GKRS for CPA meningiomas should be conducted.

Gamma knife radiosurgery for cerebellopontine angle epidermoid tumors.

BACKGROUND: Intracranial epidermoid tumors are commonly found in the cerebellopontine angle where they usually present with either trigeminal neuralgia or hemifacial spasm. Radiosurgery for these tumors has rarely been reported. The purpose of this study is to assess the safety and clinical outcome of the treatment of cerebellopontine epidermoid tumors with gamma knife radiosurgery. METHODS: This is a retrospective study involving 12 patients harboring cerebellopontine angle epidermoid tumors who underwent 15 sessions of gamma knife radiosurgery. Trigeminal pain was present in 8 patients and hemifacial spasm in 3 patients. All cases with trigeminal pain were receiving medication and still uncontrolled. One patient with hemifacial spasm was medically controlled before gamma knife and the other two were not. Two patients had undergone surgical resection prior to gamma knife treatment. The median prescription dose was 11 Gy (10-11 Gy). The tumor volumes ranged from 3.7 to 23.9 cc (median 10.5 cc). RESULTS: The median radiological follow up was 2 years (1-5 years). All tumors were controlled and one tumor shrank. The median clinical follow-up was 5 years. The trigeminal pain improved or disappeared in 5 patients, and of these, 4 cases stopped their medication and one decreased it. The hemifacial spasm resolved in 2 patients who were able to stop their medication. Facial palsy developed in 1 patient and improved with conservative treatment. Transient diplopia was also reported in 2 cases. CONCLUSION: Gamma knife radiosurgery provides good clinical control for cerebellopontine angle epidermoid tumors.

Single-session Gamma Knife radiosurgery for optic pathway/hypothalamic gliomas.

OBJECTIVE Because of their critical and central location, it is deemed necessary to fractionate when considering irradiating optic pathway/hypothalamic gliomas. Stereotactic fractionated radiotherapy is considered safer when dealing with gliomas in this location. In this study, the safety and efficacy of single-session stereotactic radiosurgery for optic pathway/hypothalamic gliomas were reviewed. METHODS Between December 2004 and June 2014, 22 patients with optic pathway/hypothalamic gliomas were treated by single-session Gamma Knife radiosurgery. Twenty patients were available for follow-up for a minimum of 1 year after treatment. The patients were 5 to 43 years (median 16 years) of age. The tumor volume was 0.15 to 18.2 cm3 (median 3.1 cm3). The prescription dose ranged from 8 to 14 Gy (median 11.5 Gy). RESULTS The mean follow-up period was 43 months. Five tumors involved the optic nerve only, and 15 tumors involved the chiasm/hypothalamus. Two patients died during the follow-up period. The tumors shrank in 12 cases, remained stable in 6 cases, and progressed in 2 cases, thereby making the tumor control rate 90%. Vision remained stable in 12 cases, improved in 6 cases, and worsened in 2 cases in which there was tumor progression. Progression-free survival was 83% at 3 years. CONCLUSIONS The initial results indicate that single-session Gamma Knife radiosurgery is a safe and effective treatment option for optic pathway/hypothalamic gliomas.

Low-dose Gamma Knife surgery for nonfunctioning pituitary adenomas.

OBJECT: The primary concern when performing Gamma Knife surgery for pituitary adenoma is preservation of vision and pituitary function while achieving tumor growth control. Higher prescribed radiation doses are typically correlated with higher incidences of postradiosurgical hormone deficiencies. The goal of the present study was to retrospectively analyze the feasibility of using a lower prescribed radiation dose in the treatment of nonfunctioning pituitary adenomas and the effect of this dose on vision, pituitary function, and tumor growth control. METHODS: The study was conducted in 38 patients with nonfunctioning pituitary adenomas, who were treated between January 2002 and July 2008. Twenty-one patients were available for follow-up (13 men and 8 women). The mean follow-up period was 44 months (range 24-90 months). Nineteen patients had previously undergone surgery. Pituitary dysfunction developed after surgery in 3 patients. One patient had an abnormal pituitary hormone profile before radiosurgery due to an attack of pituitary apoplexy. Visual field defects were present in 12 patients. The prescribed radiation dose was 12 Gy in all patients. The tumor volume ranged from 0.5 to 11.8 cm(3) (mean 4.8 cm(3)). The maximum dose to the visual pathway was kept below 10 Gy. The mean maximum dose delivered to the visual pathway was 7.9 Gy. RESULTS: The patients were followed up for a period of 24 to 90 months (mean 44 months). The size of the tumor decreased in 11 patients (52%) and remained stable in 9 patients (43%). In 1 patient there was tumor growth outside the previous radiation field (on the contralateral side). Among the 12 patients with visual field defects, 9 (75%) experienced an improvement and the remaining patients' vision remained stable. In only 4 patients was the visual improvement associated with tumor shrinkage. The hormone profile remained normal in all patients except for the 4 patients who had pituitary dysfunction before radiosurgery. CONCLUSIONS: The 12-Gy prescribed dose used in this study seems to be sufficient for producing tumor control while sparing the patient from radiation-induced pituitary dysfunction. In addition, visual improvement was reported in a number of cases. A larger series and longer follow-up are required to confirm these results.