Repeat stereotactic radiosurgery for persistent cerebral arteriovenous malformations in pediatric patients.

OBJECTIVE: The purpose of this study was to describe the long-term outcomes and associated risks related to repeat stereotactic radiosurgery (SRS) for persistent arteriovenous malformations (AVMs) in pediatric patients. METHODS: Under the auspices of the International Radiosurgery Research Foundation, this retrospective multicenter study analyzed pediatric patients who underwent repeat, single-session SRS between 1987 and 2022. The primary outcome variable was a favorable outcome, defined as nidus obliteration without hemorrhage or neurological deterioration. Secondary outcomes included rates and probabilities of hemorrhage, radiation-induced changes (RICs), and cyst or tumor formation. RESULTS: The cohort included 83 pediatric patients. The median patient age was 11 years at initial SRS and 15 years at repeat SRS. Fifty-seven children (68.7%) were managed exclusively using SRS, and 42 (50.6%) experienced hemorrhage prior to SRS. Median AVM diameter and volume were substantially different between the first (25 mm and 4.5 cm3, respectively) and second (16.5 mm and 1.6 cm3, respectively) SRS, while prescription dose and isodose line remained similar. At the 5-year follow-up evaluation from the second SRS, nidus obliteration was achieved in 42 patients (50.6%), with favorable outcome in 37 (44.6%). The median time to nidus obliteration and hemorrhage was 35.5 and 38.5 months, respectively. The yearly cumulative probability of favorable outcome increased from 2.5% (95% CI 0.5%-7.8%) at 1 year to 44% (95% CI 32%-55%) at 5 years. The probability of achieving obliteration followed a similar pattern and reached 51% (95% CI 38%-62%) at 5 years. The 5-year risk of hemorrhage during the latency period after the second SRS reached 8% (95% CI 3.2%-16%). Radiographically, 25 children (30.1%) had RICs, but only 5 (6%) were symptomatic. Delayed cyst formation occurred in 7.2% of patients, with a median onset of 47 months. No radiation-induced neoplasia was observed. CONCLUSIONS: The study results showed nidus obliteration in most pediatric patients who underwent repeat SRS for persistent AVMs. The risks of symptomatic RICs and latency period hemorrhage were quite low. These findings suggest that repeat radiosurgery should be considered when treating pediatric patients with residual AVM after prior SRS. Further study is needed to define the role of repeat SRS more fully in this population.

Pediatric cerebral cavernous malformations and stereotactic radiosurgery: an analysis of 50 cases from a multicentric study.

OBJECTIVE: Cerebral cavernous malformations (CCMs) are the second most common vascular anomaly affecting the CNS in children. Although stereotactic radiosurgery (SRS) has been proposed as an alternative to microsurgery in the management of selected cases in adults, there is a paucity of studies focusing on pediatric patients. The aim of this study was to present the outcomes and associated risks of SRS in this subgroup of patients. METHODS: This retrospective multicenter study included pediatric patients treated with single-session SRS for CCMs. The annual hemorrhage rate (AHR) was calculated before and after SRS in hemorrhagic lesions. The Engel classification was used to describe post-SRS epileptic control. Adverse radiation effects (AREs) and the occurrence of new neurological deficits were recorded. RESULTS: The study included 50 patients (median age 15.1 [IQR 5.6] years) harboring 62 CCMs. Forty-two (84%) and 22 (44%) patients had a history of hemorrhage or epilepsy prior to SRS, respectively. The AHR from diagnosis to SRS excluding the first hemorrhage was 7.19 per 100 CCM-years, dropping to 3.15 per 100 CCM-years after treatment. The cumulative risk of first hemorrhage after SRS was 7.4% (95% CI 0%-14.3%) at 5 years and 23.6% (95% CI 0%-42.2%) at 10 years. Eight hemorrhagic events involving 6 CCMs in 6 patients were recorded in the post-SRS follow-up period; 4 patients presented with transient symptoms and 4 with permanent symptoms. Of the 22 patients with pre-SRS seizures, 11 were seizure free at the last follow-up (Engel class I), 6 experienced improvement (Engel class II or III), 5 had no improvement (Engel class IVA or IVB), and 1 experienced worsening (Engel class IVC). Radiographic AREs were documented in 14.5% (9/62) of CCMs, with 4 being symptomatic. CONCLUSIONS: Single-session SRS reduces the CCM hemorrhage rate in the pediatric population and provides adequate seizure control.

Effect of cerebral arteriovenous malformation location on outcomes of repeat, single-fraction stereotactic radiosurgery: a matched-cohort analysis.

OBJECTIVE: Patients with deep-seated arteriovenous malformations (AVMs) have a higher rate of unfavorable outcome and lower rate of nidus obliteration after primary stereotactic radiosurgery (SRS). The aim of this study was to evaluate and quantify the effect of AVM location on repeat SRS outcomes. METHODS: This retrospective, multicenter study involved 505 AVM patients managed with repeat, single-session SRS. The endpoints were nidus obliteration, hemorrhage in the latency period, radiation-induced changes (RICs), and favorable outcome. Patients were split on the basis of AVM location into the deep (brainstem, basal ganglia, thalamus, deep cerebellum, and corpus callosum) and superficial cohorts. The cohorts were matched 1:1 on the basis of the covariate balancing score for volume, eloquence of location, and prescription dose. RESULTS: After matching, 149 patients remained in each cohort. The 5-year cumulative probability rates for favorable outcome (probability difference -18%, 95% CI -30.9 to -5.8%, p = 0.004) and AVM obliteration (probability difference -18%, 95% CI -30.1% to -6.4%, p = 0.007) were significantly lower in the deep AVM cohort. No significant differences were observed in the 5-year cumulative probability rates for hemorrhage (probability difference 3%, 95% CI -2.4% to 8.5%, p = 0.28) or RICs (probability difference 1%, 95% CI -10.6% to 11.7%, p = 0.92). The median time to delayed cyst formation was longer with deep-seated AVMs (deep 62 months vs superficial 12 months, p = 0.047). CONCLUSIONS: AVMs located in deep regions had significantly lower favorable outcomes and obliteration rates compared with superficial lesions after repeat SRS. Although the rates of hemorrhage in the latency period and RICs in the two cohorts were comparable, delayed cyst formation occurred later in patients with deep-seated AVMs.

Clinical outcomes following stereotactic radiosurgery for cerebral cavernous malformations of the basal ganglia and thalamus.

OBJECTIVE: There are few reports of outcomes following stereotactic radiosurgery (SRS) for the management of cerebral cavernous malformations (CCMs) of the basal ganglia or thalamus. Therefore, the authors aimed to clarify these outcomes. METHODS: Centers participating in the International Radiosurgery Research Foundation were queried for CCM cases managed with SRS from October 2001 to February 2021. The primary outcome of interest was hemorrhage-free survival (HFS) with a secondary outcome of symptomatic adverse radiation events (AREs). Assessment of the association of prognostic factors with HFS was conducted via Kaplan-Meier analysis and log-rank test. Chi-square tests were conducted to assess potential factors associated with the incidence of AREs. RESULTS: Seventy-three patients were identified. The median patient age was 43.5 years (range 4.4-79.5 years). Fifty-nine (80.8%) patients had hemorrhage prior to SRS. The median treatment volume was 0.9 cm3 (range 0.07-10.1 cm3) with a median margin prescription dose (MPD) of 12 Gy (range 10-20 Gy). One-, 3-, 5-, and 10-year HFS were 93.0%, 89.9%, 89.9%, and 83.0%, respectively, with one hemorrhage-related death approximately 1 year after SRS and nearly 60% and 30% of patients having improvement or stability of symptoms, respectively. There was no correlation between lesion size or MPD and HFS. Seven (9.6%) patients experienced AREs (MPDs > 12 Gy in all cases). Lesion size > 1.0 cm3 was correlated with the incidence of an ARE (p = 0.019). Forty-two (93.3%) of 45 patients treated with an MPD ≤ 12 Gy experienced neither hemorrhage nor AREs following SRS versus 17 (60.7%) of 28 patients treated with an MPD > 12 Gy (p = 0.0006). CONCLUSIONS: SRS is a reasonable treatment strategy and confers clinical stability or improvement and hemorrhage avoidance in patients harboring CCMs of the basal ganglia or thalamus. An MPD of approximately 12 Gy is recommended for the management of CCM.

Third Stereotactic Radiosurgery for Residual Arteriovenous Malformations: A Retrospective Multicenter Study.

BACKGROUND AND OBJECTIVES: There are no studies evaluating the efficacy and safety of more than 2 stereotactic radiosurgery (SRS) procedures for cerebral arteriovenous malformations (AVM). The aim of this study was to provide evidence on the role of third single-session SRS for AVM residual. METHODS: This multicenter, retrospective study included patients managed with a third single-session SRS procedure for an AVM residual. The primary study outcome was defined as AVM nidus obliteration without AVM bleeding or symptomatic radiation-induced changes (RIC). Secondary outcomes evaluated were AVM obliteration, AVM hemorrhage, asymptomatic, and symptomatic RIC. RESULTS: Thirty-eight patients (20/38 [52.6%] females, median age at third SRS 34.5 [IQR 20] years) were included. The median clinical follow-up was 46 (IQR 14.8) months, and 17/38 (44.7%) patients achieved favorable outcome. The 3-year and 5-year cumulative probability rates of favorable outcome were 23% (95% CI = 10%-38%) and 53% (95% CI = 29%-73%), respectively. The cumulative probability of AVM obliteration at 3 and 5 years after the third SRS was 23% (95% CI = 10%-37%) and 54% (95% CI = 29%-74%), respectively. AVM bleeding occurred in 2 patients, and 1 of them underwent subsequent resection. The cumulative probability rate of post-SRS AVM hemorrhage remained constant at 5.3% (95% CI = 1%-16%) during the first 5 years of follow-up. Transient symptomatic RIC managed conservatively occurred in 5/38 patients (13.2%) at a median time of 12.5 (IQR 22.5) months from third SRS. Radiation-induced cyst formation was noted in 1 patient (4.2%) 19 months post-SRS. No mortality, radiation-associated malignancy, or permanent symptomatic RIC was noted during follow-up. CONCLUSION: A third single-session SRS to treat a residual intracranial AVM offers obliteration in most patients. The risk of RIC was low, and these effects were transient. While not often required, a third SRS can be performed in patients with persistent residual AVMs.

Outcome Evaluation of Repeat Stereotactic Radiosurgery for Cerebral Arteriovenous Malformations.

BACKGROUND: Repeat stereotactic radiosurgery (SRS) for persistent cerebral arteriovenous malformation (AVM) has generally favorable patient outcomes. However, reporting studies are limited by small patient numbers and single-institution biases. The purpose of this study was to provide the combined experience of multiple centers, in an effort to fully define the role of repeat SRS for patients with arteriovenous malformation. METHODS: This multicenter, retrospective cohort study included patients treated with repeat, single-fraction SRS between 1987 and 2022. Follow-up began at repeat SRS. The primary outcome was a favorable patient outcome, defined as a composite of nidus obliteration in the absence of hemorrhage or radiation-induced neurological deterioration. Secondary outcomes were obliteration, hemorrhage risk, and symptomatic radiation-induced changes. Competing risk analysis was performed to compute yearly rates and identify predictors for each outcome. RESULTS: The cohort comprised 505 patients (254 [50.3%] males; median [interquartile range] age, 34 [15] years) from 14 centers. The median clinical and magnetic resonance imaging follow-up was 52 (interquartile range, 61) and 47 (interquartile range, 52) months, respectively. At last follow-up, favorable outcome was achieved by 268 (53.1%) patients (5-year probability, 50% [95% CI, 45%-55%]) and obliteration by 300 (59.4%) patients (5-year probability, 56% [95% CI, 51%-61%]). Twenty-eight patients (5.6%) experienced post-SRS hemorrhage with an annual incidence rate of 1.38 per 100 patient-years. Symptomatic radiation-induced changes were evident in 28 (5.6%) patients, with most occurring in the first 3 years. Larger nidus volumes (between 2 and 4 cm3, subdistribution hazard, 0.61 [95% CI, 0.44-0.86]; P=0.005; >4 cm3, subdistribution hazard, 0.47 [95% CI, 0.32-0.7]; P<0.001) and brainstem/basal ganglia involvement (subdistribution hazard, 0.6 [95% CI, 0.45-0.81]; P<0.001) were associated with reduced probability of favorable outcome. CONCLUSIONS: Repeat SRS confers reasonable obliteration rates with a low complication risk. With most complications occurring in the first 3 years, extending the latency period to 5 years generally increases the rate of favorable patient outcomes and reduces the necessity of a third intervention.

Stereotactic Radiosurgery for Meningiomas in Children and Adolescents: An International Multi-Institutional Study.

BACKGROUND AND OBJECTIVES: Meningiomas in children are uncommon, with distinct characteristics that set them apart from their adult counterparts. The existing evidence for stereotactic radiosurgery (SRS) in this patient population is limited to only case series. The objective of this study was to evaluate the safety and efficacy of SRS in managing pediatric meningiomas. METHODS: Children and adolescents who had been treated for meningioma with single-fraction SRS were included in this retrospective, multicenter study. The assessment included local tumor control, any complications related to the tumor or SRS, and the emergence of new neurological deficits after SRS. RESULTS: The cohort included 57 patients (male-to-female ratio 1.6:1) with a mean age of 14.4 years who were managed with single-fraction SRS for 78 meningiomas. The median radiological and clinical follow-up periods were 69 months (range, 6-268) and 71 months (range, 6-268), respectively. At the last follow-up, tumor control (tumor stability and regression) was achieved in 69 (85.9%) tumors. Post-SRS, new neurological deficits occurred in 2 (3.5%) patients. Adverse radiation effects occurred in 5 (8.8%) patients. A de novo aneurysm was observed in a patient 69 months after SRS. CONCLUSION: SRS seems to be a safe and effective up-front or adjuvant treatment option for surgically inaccessible, recurrent, or residual pediatric meningiomas.

Stereotactic radiosurgery for Koos grade IV vestibular schwannoma: a multi-institutional study.

OBJECTIVE: Though stereotactic radiosurgery (SRS) is an established safe treatment for small- and medium-sized vestibular schwannomas (VSs), its role in the management of Koos grade IV VS is still unclear. In this retrospective multicenter study, the authors evaluated tumor control and the patient outcomes of primary, single-session SRS treatment for Koos grade IV VS. METHODS: This study included patients treated with primary, single-session SRS for Koos grade IV VS at 10 participating centers. Only those patients presenting with non-life-threatening or incapacitating symptoms and at least 12 months of clinical and neuroimaging follow-up were eligible for inclusion. Relevant data were collected, and the Kaplan-Meier method was used to perform time-dependent analysis for post-SRS tumor control, hearing preservation, and facial nerve function preservation. Univariate and multivariate analyses were performed for outcome measures using Cox regression analysis. RESULTS: Six hundred twenty-seven patients (344 females, median patient age 54 [IQR 22] years) treated with primary SRS were included in this study. The median tumor volume was 8.7 (IQR 5) cm3. Before SRS, serviceable hearing, facial nerve weakness (House-Brackmann grade > I), and trigeminal neuropathy were present in 205 (33%), 48 (7.7%), and 203 (32.4%) patients, respectively. The median prescription dose was 12 (IQR 1) Gy. At a median radiological follow-up of 38 (IQR 54) months, tumor control was achieved in 94.1% of patients. Early tumor expansion occurred in 67 (10.7%) patients and was associated with a loss of tumor control at the last follow-up (p = 0.001). Serviceable hearing preservation rates at the 5- and 10-year follow-ups were 65% and 44.6%, respectively. Gardner-Robertson class > 1 (p = 0.003) and cochlear dose ≥ 4 Gy (p = 0.02) were risk factors for hearing loss. Facial nerve function deterioration occurred in 19 (3.0%) patients at the last follow-up and was associated with margin doses ≥ 13 Gy (p = 0.03) and early tumor expansion (p = 0.04). Post-SRS, 33 patients developed hydrocephalus requiring shunting. Adverse radiation effects occurred in 92 patients and were managed medically or surgically in 34 and 18 cases, respectively. CONCLUSIONS: SRS is a safe and effective method of obtaining tumor control in patients with Koos grade IV VS presenting with non-life-threatening or debilitating symptoms, especially those with surgical comorbidities that contraindicate resection. To decrease the incidence of post-SRS facial palsy, a prescription dose < 13 Gy is recommended.

Stereotactic Radiosurgery for Benign Cavernous Sinus Meningiomas: A Multicentre Study and Review of the Literature.

Cavernous sinus meningiomas (CSMs) remain a surgical challenge due to the intimate involvement of their contained nerves and blood vessels. Stereotactic radiosurgery (SRS) is a safe and effective minimally invasive alternative for the treatment of small- to medium-sized CSMs. Objective: To assess the medium- to long-term outcomes of SRS for CSMs with respect to tumour growth, prevention of further neurological deterioration and improvement of existing neurological deficits. This multicentric study included data from 15 European institutions. We performed a retrospective observational analysis of 1222 consecutive patients harbouring 1272 benign CSMs. All were treated with Gamma Knife stereotactic radiosurgery (SRS). Clinical and imaging data were retrieved from each centre and entered into a common database. All tumours with imaging follow-up of less than 24 months were excluded. Detailed results from 945 meningiomas (86%) were then analysed. Clinical neurological outcomes were available for 1042 patients (85%). Median imaging follow-up was 67 months (mean 73.4, range 24-233). Median tumour volume was 6.2 cc (+/-7), and the median marginal dose was 14 Gy (+/-3). The post-treatment tumour volume decreased in 549 (58.1%), remained stable in 336 (35.6%) and increased in only 60 lesions (6.3%), yielding a local tumour control rate of 93.7%. Only 27 (2.8%) of the 60 enlarging tumours required further treatment. Five- and ten-year actuarial progression-free survival (PFS) rates were 96.7% and 90.1%, respectively. Tumour control rates were higher for women than men (p = 0.0031), and also for solitary sporadic meningiomas (p = 0.0201). There was no statistically significant difference in outcome for imaging-defined meningiomas when compared with histologically proven WHO Grade-I meningiomas (p = 0.1212). Median clinical follow up was 61 months (mean 64, range 6-233). Permanent morbidity occurred in 5.9% of cases at last follow-up. Stereotactic radiosurgery is a safe and effective method for treating benign CSM in the medium term to long term.

Stereotactic radiosurgery for Rathke's cleft cysts: an international multicenter study.

OBJECTIVE: Rathke's cleft cysts (RCCs) are sellar collections from an incompletely regressed Rathke's pouch. Common symptoms of RCCs can include headaches, visual loss, and endocrinopathy. Surgery is required in some cases of symptomatic or growing RCCs. Recurrence after surgery is common (range 10%-40%). Stereotactic radiosurgery (SRS) has been used in an attempt to control growth and symptoms, but outcomes are not well known. The authors sought to study the outcomes of RCCs following Gamma Knife surgery for both salvage and initial treatment. METHODS: The outcomes of 25 patients with RCCs who underwent SRS between 2001 and 2020 were reviewed. Four patients received initial SRS and 21 were treated with salvage SRS. Diagnosis was based on imaging or histopathology. Cyst control was defined as stability or regression of the cyst. Kaplan-Meier analysis was used to determine time to recurrence and determine potential factors for recurrence. RESULTS: The respective median clinical follow-up and margin dose were 6.5 years and 12 Gy. Overall control was achieved in 19 (76%) of 25 patients, and 4 recurrences required further intervention. The average time to recurrence was 35.6 months in those RCCs that recurred. Visual recovery occurred in 14 (93.3%) of 15 patients and no new post-SRS visual deficits occurred. The presence of a pretreatment visual deficit was often an indicator of RCC regrowth. All 3 patients with pretreatment hyperprolactinemia experienced resolution after SRS. New endocrinopathy related to SRS was noted in 5 (20%) of 25 patients, all of which were thyroid and/or cortisol axis related. Upfront SRS was used in 4 patients. No new endocrinopathies or visual deficits developed after upfront SRS, and the 1 patient with a pretreatment visual deficit recovered. One of the 4 patients with upfront SRS experienced a recurrence after 7.5 years. CONCLUSIONS: SRS produced effective recovery of visual deficits and carries a low risk for new visual deficits. Cyst control was achieved in approximately three-fourths of the patients. Following SRS, patients without pretreatment visual deficits are less likely to have RCC regrowth. Endocrinopathy can occur after SRS, similar to other sellar mass lesions. Initial SRS shows the potential for long-term cyst control, with improvement of symptoms and a low risk for complications.

Dose to neuroanatomical structures surrounding pituitary adenomas and the effect of stereotactic radiosurgery on neuroendocrine function: an international multicenter study.

OBJECTIVE: Stereotactic radiosurgery (SRS) provides a safe and effective therapeutic modality for patients with pituitary adenomas. The mechanism of delayed endocrine deficits based on targeted radiation to the hypothalamic-pituitary axis remains unclear. Radiation to normal neuroendocrine structures likely plays a role in delayed hypopituitarism after SRS. In this multicenter study by the International Radiosurgery Research Foundation (IRRF), the authors aimed to evaluate radiation tolerance of structures surrounding pituitary adenomas and identify predictors of delayed hypopituitarism after SRS for these tumors. METHODS: This is a retrospective review of patients with pituitary adenomas who underwent single-fraction SRS from 1997 to 2019 at 16 institutions within the IRRF. Dosimetric point measurements of 14 predefined neuroanatomical structures along the hypothalamus, pituitary stalk, and normal pituitary gland were made. Statistical analyses were performed to determine the impact of doses to critical structures on clinical, radiographic, and endocrine outcomes. RESULTS: The study cohort comprised 521 pituitary adenomas treated with SRS. Tumor control was achieved in 93.9% of patients over a median follow-up period of 60.1 months, and 22.5% of patients developed new loss of pituitary function with a median treatment volume of 3.2 cm3. Median maximal radiosurgical doses to the hypothalamus, pituitary stalk, and normal pituitary gland were 1.4, 7.2, and 11.3 Gy, respectively. Nonfunctioning adenoma status, younger age, higher margin dose, and higher doses to the pituitary stalk and normal pituitary gland were independent predictors of new or worsening hypopituitarism. Neither the dose to the hypothalamus nor the ratio between doses to the pituitary stalk and gland were significant predictors. The threshold of the median dose to the pituitary stalk for new endocrinopathy was 10.7 Gy in a single fraction (OR 1.77, 95% CI 1.17-2.68, p = 0.006). CONCLUSIONS: SRS for the treatment of pituitary adenomas affords a high tumor control rate with an acceptable risk of new or worsening endocrinopathy. This evaluation of point dosimetry to adjacent neuroanatomical structures revealed that doses to the pituitary stalk, with a threshold of 10.7 Gy, and doses to the normal gland significantly increased the risk of post-SRS hypopituitarism. In patients with preserved pre-SRS neuroendocrine function, limiting the dose to the pituitary stalk and gland while still delivering an optimal dose to the tumor appears prudent.

Cognitive deficits and clinical symptoms in patients with treatment-refractory obsessive-compulsive disorder: The role of slowness in information processing.

Patients with Obsessive-Compulsive Disorder (OCD) present neuropsychological deficits across different cognitive domains, especially in executive functioning and information processing speed. Some studies have even suggested that speed deficits may underlie poor neuropsychological performance. However, this hypothesis remains unanswered in both OCD general population and OCD refractory subgroup. In addition, it is not clear whether such deficits are secondary to the clinical symptoms or may constitute a primary deficit. The aim of this study was to explore the speed of processing hypothesis in treatment-refractory OCD patients, and to clarify to what extent slowness is related to psychopathological symptoms. Both clinical and neuropsychological examination was conducted to assess 39 OCD refractory patients candidates for neurosurgery and 39 healthy matched individuals. Principal component analysis revealed a three-component structure in the neuropsychological battery being used, including a speed of processing, working memory, and conflict monitoring components. Group comparisons revealed that OCD patients performed significantly worse than healthy individuals in speed measures, but no differences were found in executive tests not influenced by time. Correlation analyses revealed a lack of association between neuropsychological and clinical measures. The results suggest that treatment-refractory OCD patients exhibit a primary deficit in information processing speed independent of clinical symptoms.

Stereotactic Radiosurgery for Differentiated Thyroid Cancer Brain Metastases: An International, Multicenter Study.

Background: Brain metastases (BM) from differentiated thyroid cancer are rare. Stereotactic radiosurgery (SRS) is commonly used for the treatment of BMs; however, the experience with SRS for thyroid cancer BMs remains limited. The goal of this international, multi-centered study was to evaluate the efficacy and safety of SRS for thyroid cancer BMs. Methods: From 10 institutions participating in the International Radiosurgery Research Foundation, we pooled patients with established papillary or follicular thyroid cancer diagnosis who underwent SRS for histologically confirmed or radiologically suspected BMs. We investigated patient overall survival (OS), local tumor control, and adverse radiation events (AREs). Results: We studied 42 (52% men) patients who underwent SRS for 122 papillary (83%) or follicular (17%) thyroid cancer BMs. The mean age at SRS was 59.86 ± 12.69 years. The mean latency from thyroid cancer diagnosis to SRS for BMs was 89.05 ± 105.49 months. The median number of BMs per patient was 2 (range: 1-10 BMs). The median SRS treatment volume was 0.79 cm3 (range: 0.003-38.18 cm3), and the median SRS prescription dose was 20 Gy (range: 8-24 Gy). The median survival after SRS for BMs was 14 months (range: 3-58 months). The OS was significantly shorter in patients harboring ≥2 BMs, when compared with patients with one BM (Log-rank = 5.452, p = 0.02). Two or more BMs (odds ratio [OR] = 3.688; confidence interval [CI]: 1.143-11.904; p = 0.03) and lower Karnofsky performance score at the time of SRS (OR = 0.807; CI: 0.689-0.945; p = 0.008) were associated with shorter OS. During post-SRS imaging follow-up of 25.21 ± 30.49 months, local failure (progression and/or radiation necrosis) of BMs treated with SRS was documented in five (4%) BMs at 7.2 ± 7.3 months after the SRS. At the last imaging follow-up, the majority of patients with available imaging data had stable intracranial disease (33%) or achieved complete (26%) or partial (24%) response. There were no clinical AREs. Post-SRS peritumoral T2/fluid attenuated inversion recovery signal hyperintensity was noted in 7% BMs. Conclusion: The SRS allows durable local control of papillary and follicular thyroid cancer BMs in the vast majority of patients. Higher number of BMs and worse functional status at the time of SRS are associated with shorter OS in patients with thyroid cancer BMs. The SRS is safe and is associated with a low risk of AREs.

Stereotactic radiosurgery for treatment of radiation-induced meningiomas: a multiinstitutional study.

OBJECTIVE: Radiation-induced meningiomas (RIMs) are associated with aggressive clinical behavior. Stereotactic radiosurgery (SRS) is sometimes considered for selected RIMs. The authors investigated the effectiveness and safety of SRS for the management of RIMs. METHODS: From 12 institutions participating in the International Radiosurgery Research Foundation, the authors pooled patients who had prior cranial irradiation and were subsequently clinically diagnosed with WHO grade I meningiomas that were managed with SRS. RESULTS: Fifty-two patients underwent 60 SRS procedures for histologically confirmed or radiologically suspected WHO grade I RIMs. The median ages at initial cranial radiation therapy and SRS for RIM were 5.5 years and 39 years, respectively. The most common reasons for cranial radiation therapy were leukemia (21%) and medulloblastoma (17%). There were 39 multiple RIMs (35%), the mean target volume was 8.61 ± 7.80 cm3, and the median prescription dose was 14 Gy. The median imaging follow-up duration was 48 months (range 4-195 months). RIM progressed in 9 patients (17%) at a median duration of 30 months (range 3-45 months) after SRS. Progression-free survival at 5 years post-SRS was 83%. Treatment volume ≥ 5 cm3 predicted progression (HR 8.226, 95% CI 1.028-65.857, p = 0.047). Seven patients (14%) developed new neurological symptoms or experienced SRS-related complications or T2 signal change from 1 to 72 months after SRS. CONCLUSIONS: SRS is associated with durable local control of RIMs in the majority of patients and has an acceptable safety profile. SRS can be considered for patients and tumors that are deemed suboptimal, poor surgical candidates, and those whose tumor again progresses after removal.

Klippel-Trenaunay-Weber Syndrome Associated with Multiple Cerebral Arteriovenous Malformations: Usefulness of Gamma Knife Stereotactic Radiosurgery in This Syndrome.

BACKGROUND: Klippel-Trenaunay-Weber syndrome (KTWS) is characterized by the presence of a combined vascular malformation of capillaries, veins, and lymphatic vessels; congenital venous abnormalities; and limb hypertrophy. Its association with neurovascular abnormalities is infrequent, and the presence of intracranial arteriovenous malformations (AVMs) is extremely rare. CASE DESCRIPTION: We report a case of a 48-year-old male diagnosed with KTWS who spontaneously presented with a cerebral hemorrhage. Computed tomography scan and angio-computed tomography studies revealed bleeding associated with AVM rupture. In the conventional arteriography study, 10 small (<1 cm) AVMs were observed. The patient presented a good clinical recovery. These multiple small lesions were not considered susceptible to surgical or endovascular treatments. Therefore all lesions were treated with Gamma Knife stereotactic radiosurgery since it attains the highest dose drop and minimal irradiation of the healthy parenchyma. One year after the treatment, the lesions have shrunk. CONCLUSIONS: Cerebral AVMs are extremely rare in KTWS cases; however, their presence can have serious consequences if they are treated. We find it advisable to include brain imaging tests, such as nuclear magnetic resonance imaging, to diagnose and monitor KTWS. Furthermore, a Gamma Knife may be useful when multiple AVMs are present.

Early versus late Gamma Knife radiosurgery for Cushing's disease after prior resection: results of an international, multicenter study.

OBJECTIVE: The optimal time to perform stereotactic radiosurgery after incomplete resection of adrenocorticotropic hormone (ACTH)-producing pituitary adenoma in patients with Cushing's disease (CD) remains unclear. In patients with persistent CD after resection of ACTH-producing pituitary adenoma, the authors evaluated the association of the interval between resection and Gamma Knife radiosurgery (GKRS) with outcomes. METHODS: Pooled data from 10 institutions participating in the International Radiosurgery Research Foundation were used in this study. RESULTS: Data from 255 patients with a mean follow-up of 65.59 ± 49.01 months (mean ± SD) were analyzed. Seventy-seven patients (30%) underwent GKRS within 3 months; 46 (18%) from 4 to 6 months; 34 (13%) from 7 to 12 months; and 98 (38%) at > 12 months after the resection. Actuarial endocrine remission rates were higher in patients who underwent GKRS ≤ 3 months than when treatment was > 3 months after the resection (78% and 65%, respectively; p = 0.017). Endocrine remission rates were lower in patients who underwent GKRS at > 12 months versus ≤ 12 months after the resection (57% vs 76%, respectively; p = 0.006). In multivariate Cox regression analyses adjusted for clinical and treatment characteristics, early GKRS was associated with increased probability of endocrine remission (hazard ratio [HR] 1.518, 95% CI 1.039-2.218; p = 0.031), whereas late GKRS (HR 0.641, 95% CI 0.448-0.919; p = 0.015) was associated with reduced probability of endocrine remission. The incidence of some degree of new pituitary deficiency (p = 0.922), new visual deficits (p = 0.740), and other cranial nerve deficits (p = 0.610) was not significantly related to time from resection to GKRS. CONCLUSIONS: Early GKRS is associated with an improved endocrine remission rate, whereas later GKRS is associated with a lower rate of endocrine remission after pituitary adenoma resection. Early GKRS should be considered for patients with CD after incomplete pituitary adenoma resection.

Whole Sella vs Targeted Stereotactic Radiosurgery for Acromegaly: A Multicenter Matched Cohort Study.

BACKGROUND: Targeted stereotactic radiosurgery (SRS) with sparing of the residual pituitary is the traditional radiosurgical method for pituitary adenomas. Whole-sella SRS is an alternative choice for radiologically indeterminate or large adenomas, the safety and efficacy of which has yet to be determined. OBJECTIVE: To determine if whole-sella SRS in acromegaly would have comparable radiographic and biochemical control to targeted SRS. We performed a multicenter, retrospective matched cohort study to compare outcomes between groups. METHODS: We conducted a retrospective review of acromegalic patients who underwent SRS from 1990 to 2016 at 10 centers participating in the International Radiosurgery Research Foundation. Whole-sella and targeted SRS patients were then matched in a 1:1 ratio. RESULTS: A total of 128 patients were eligible for inclusion. Whole-sella patients had a higher pre-SRS random serum growth hormone, larger treatment volume, and higher maximum point dose to the optic apparatus. The rates of initial/durable endocrine remission, new loss of pituitary function, and new cranial neuropathy were similar between groups. Mortality and new visual deficit were higher in the whole-sella cohort, though not statistically significant. CONCLUSION: There was no difference in biochemical remission or recurrence between treatment groups. Although not statistically significant, the higher rates of tumor regression and lower rates of mortality and new visual deficit may suggest consideration of targeted SRS over whole-sella SRS in acromegaly treatment. Further research is needed to determine the association between visual deficits and mortality with whole-sella SRS.

Outcomes of stereotactic radiosurgery for pilocytic astrocytoma: an international multiinstitutional study.

OBJECTIVE: The current standard initial therapy for pilocytic astrocytoma is maximal safe resection. Radiation therapy is considered for residual, recurrent, or unresectable pilocytic astrocytomas. However, the optimal radiation strategy has not yet been established. Here, the authors describe the outcomes of stereotactic radiosurgery (SRS) for pilocytic astrocytoma in a large multiinstitutional cohort. METHODS: An institutional review board-approved multiinstitutional database of patients treated with Gamma Knife radiosurgery (GKRS) between 1990 and 2016 was queried. Data were gathered from 9 participating International Radiosurgery Research Foundation (IRRF) centers. Patients with a histological diagnosis of pilocytic astrocytoma treated using a single session of GKRS and with at least 6 months of follow-up were included in the analysis. RESULTS: A total of 141 patients were analyzed in the study. The median patient age was 14 years (range 2-84 years) at the time of GKRS. The median follow-up was 67.3 months. Thirty-nine percent of patients underwent SRS as the initial therapy, whereas 61% underwent SRS as salvage treatment. The median tumor volume was 3.45 cm3. The tumor location was the brainstem in 30% of cases, with a nonbrainstem location in the remainder. Five- and 10-year overall survival rates at the last follow-up were 95.7% and 92.5%, respectively. Five- and 10-year progression-free survival (PFS) rates were 74.0% and 69.7%, respectively. On univariate analysis, an age < 18 years, tumor volumes < 4.5 cm3, and no prior radiotherapy or chemotherapy were identified as positive prognostic factors for improved PFS. On multivariate analysis, only prior radiotherapy was significant for worse PFS. CONCLUSIONS: This represents the largest study of single-session GKRS for pilocytic astrocytoma to date. Favorable long-term PFS and overall survival were observed with GKRS. Further prospective studies should be performed to evaluate appropriate radiosurgery dosing, timing, and sequencing of treatment along with their impact on toxicity and the quality of life of patients with pilocytic astrocytoma.

The benefit and risk of stereotactic radiosurgery for prolactinomas: an international multicenter cohort study.

OBJECTIVE: The most common functioning pituitary adenoma is prolactinoma. Patients with medically refractory or residual/recurrent tumors that are not amenable to resection can be treated with stereotactic radiosurgery (SRS). The aim of this multicenter study was to evaluate the role of SRS for treating prolactinomas. METHODS: This retrospective study included prolactinomas treated with SRS between 1997 and 2016 at ten institutions. Patients' clinical and treatment parameters were investigated. Patients were considered to be in endocrine remission when they had a normal level of prolactin (PRL) without requiring dopamine agonist medications. Endocrine control was defined as endocrine remission or a controlled PRL level ≤ 30 ng/ml with dopamine agonist therapy. Other outcomes were evaluated including new-onset hormone deficiency, tumor recurrence, and new neurological complications. RESULTS: The study cohort comprised 289 patients. The endocrine remission rates were 28%, 41%, and 54% at 3, 5, and 8 years after SRS, respectively. Following SRS, 25% of patients (72/289) had new hormone deficiency. Sixty-three percent of the patients (127/201) with available data attained endocrine control. Three percent of patients (9/269) had a new visual complication after SRS. Five percent of the patients (13/285) were recorded as having tumor progression. A pretreatment PRL level ≤ 270 ng/ml was a predictor of endocrine remission (p = 0.005, adjusted HR 0.487). An increasing margin dose resulted in better endocrine control after SRS (p = 0.033, adjusted OR 1.087). CONCLUSIONS: In patients with medically refractory prolactinomas or a residual/recurrent prolactinoma, SRS affords remarkable therapeutic effects in endocrine remission, endocrine control, and tumor control. New-onset hypopituitarism is the most common adverse event.

Primary versus postoperative stereotactic radiosurgery for acromegaly: a multicenter matched cohort study.

OBJECTIVE: The role of primary stereotactic radiosurgery (SRS) in patients with medically refractory acromegaly who are not operative candidates or who refuse resection is poorly understood. The aim of this multicenter, matched cohort study was to compare the outcomes of primary versus postoperative SRS for acromegaly. METHODS: The authors reviewed an International Radiosurgery Research Foundation database of 398 patients with acromegaly who underwent SRS and categorized them into primary or postoperative cohorts. Patients in the primary SRS cohort were matched, in a 1:2 ratio, to those in the postoperative SRS cohort, and the outcomes of the 2 matched cohorts were compared. RESULTS: The study cohort comprised 78 patients (median follow-up 66.4 months), including 26 and 52 in the matched primary and postoperative SRS cohorts, respectively. In the primary SRS cohort, the actuarial endocrine remission rates at 2 and 5 years were 20% and 42%, respectively. The Cox proportional hazards model showed that a lower pre-SRS insulin-like growth factor-1 level was predictive of initial endocrine remission (p = 0.03), whereas a lower SRS margin dose was predictive of biochemical recurrence after initial remission (p = 0.01). There were no differences in the rates of radiological tumor control (p = 0.34), initial endocrine remission (p = 0.23), biochemical recurrence after initial remission (p = 0.33), recurrence-free survival (p = 0.32), or hypopituitarism (p = 0.67) between the 2 matched cohorts. CONCLUSIONS: Primary SRS has a reasonable benefit-to-risk profile for patients with acromegaly in whom resection is not possible, and it has similar outcomes to endocrinologically comparable patients who undergo postoperative SRS. SRS with medical therapy in the latent period can be used as an alternative to surgery in selected patients who cannot or do not wish to undergo resection.