Tag: gamma-knife

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Effect of Prior Embolization on Cerebral Arteriovenous Malformation Radiosurgery Outcomes

AVM

Neurosurgery 77:406–417, 2015

Embolization before stereotactic radiosurgery (SRS) for cerebral arteriovenous malformations (AVM) has been shown to negatively affect obliteration rates, but its impact on the risks of radiosurgery-induced complications and latency period hemorrhage is poorly defined.

OBJECTIVE: To determine, in a case-control study, the effect of prior embolization on AVM SRS outcomes.

METHODS: We evaluated a database of AVM patients who underwent SRS. Propensity score analysis was used to match the case (embolized nidi) and control (nonembolized nidi) cohorts. AVM angioarchitectural complexity was defined as the sum of the number of major feeding arteries and draining veins to the nidus. Multivariate Cox proportional hazards regression analyses were performed on the overall study population to determine independent predictors of obliteration and radiation-induced changes.

RESULTS: The matching process yielded 242 patients in each cohort. The actuarial obliteration rates were significantly lower in the embolized (31%, 49% at 5, 10 years, respectively) compared with the nonembolized (48%, 64% at 5, 10 years, respectively) cohort (P = .003). In the multivariate analysis for obliteration, lower angioarchitectural complexity (P , .001) and radiologically evident radiation-induced changes (P = .016) were independent predictors, but embolization was not significant (P = .744). In the multivariate analysis for radiologic radiation-induced changes, lack of prior embolization (P = .009) and fewer draining veins (P = .011) were independent predictors.

CONCLUSION: The effect of prior embolization on AVM obliteration after SRS may be significantly confounded by nidus angioarchitectural complexity. Additionally, embolization could reduce the risk of radiation-induced changes. Thus, combined embolization and SRS may be warranted for appropriately selected nidi.

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Radiosurgery for symptomatic cavernous malformations: A multi‑institutional retrospective study in Japan

Gamma knife radiosurgery for brainstem cavernous malformations- should a patient wait for the rebleed?

Surg Neurol Int 2015;6:S249-57

A group study for symptomatic cavernous malformation (CM) treated with gamma knife (GK) surgery was performed.

Methods: A total of 298 cases collected from 23 GK centers across Japan were included. Hemorrhage was the most common manifestation, followed by seizures and neurological deficits. Most of the lesions were located in the brainstem and basal ganglia, followed by the cerebral or cerebellar hemispheres. The CMs, which had a mean diameter of 14.8 mm, were treated using GK surgery with a mean marginal dose of 14.6 Gy.

Results: In terms of hemorrhage‑free survival (HFS), a marked dissociation was confirmed between the hemorrhage and seizure groups, while no obvious difference was noted between sexes. Superficial CMs located in cerebellum or lobar regions responded to the treatment better than deeply located CMs in the basal ganglia or brainstem. No significant difference of dose‑dependent response was seen for three different ranges of marginal dose: Less than 15 Gy, between 15 and 20 Gy, and more than 20 Gy. Complications were more frequent after a marginal dose of over 15 Gy and in patients with lesions more than 15 mm in diameter. The rates of annual hemorrhage were estimated to be 7.4% during the first 2 years after radiosurgery and 2.8% thereafter. The overall hemorrhage rate after radiosurgery was 4.4%/year/patient.

Conclusion: The risk of hemorrhage is considerably reduced after GK treatment. The HFS as well as annual hemorrhage rate after GK treatment was apparently superior to that after conservative treatment for symptomatic CMs. To optimize the success of GK treatment, it is important to reduce the incidence of complications.

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A treatment paradigm for high-grade brain arteriovenous malformations: volume-staged radiosurgical downgrading followed by microsurgical resection

A treatment paradigm for high-grade brain arteriovenous malformations- volume-staged radiosurgical downgrading followed by microsurgical resection

J Neurosurg 122:419–432, 2015

The surgical treatment of many large arteriovenous malformations (AVMs) is associated with substantial risks, and many are considered inoperable. Furthermore, AVMs larger than 3 cm in diameter are not usually treated with conventional single-session radiosurgery encompassing the entire AVM volume. Volume-staged stereotactic radiosurgery (VS-SRS) is an option for large AVMs, but it has mixed results. The authors report on a series of patients with highgrade AVMs who underwent multiple VS-SRS sessions with resultant downgrading of the AVMs, followed by resection.

Methods. A cohort of patients was retrieved from a single-institution AVM patient registry consisting of prospectively collected data. VS-SRS was performed as a planned intentional treatment. Surgery was considered as salvage therapy in select patients.

Results Sixteen AVMs underwent VS-SRS followed by surgery. Four AVMs presented with rupture. The mean patient age was 25.3 years (range 13–54 years). The average initial Spetzler-Martin grade before any treatment was 4, while the average supplemented Spetzler-Martin grade (Spetzler-Martin plus Lawton-Young) was 7.1. The average AVM size in maximum dimension was 5.9 cm (range 3.3–10 cm). All AVMs were supratentorial in location and all except one were in eloquent areas of the brain, with 7 involving primary motor cortex. The mean number of VS-SRS sessions was 2.7 (range 2–5 sessions). The mean interval between first VS-SRS session and resection was 5.7 years. There were 4 hemorrhages that occurred after VS-SRS. The average Spetzler-Martin grade was reduced to 2.5 (downgrade, -1.5) and the average supplemented Spetzler-Martin grade was reduced to 5.6 (downgrade, -1.5). The maximum AVM size was reduced to an average of 3.0 cm (downsize = -2.9 cm). The mean modified Rankin Scale (mRS) scores were 1.2, 2.3, and 2.2 before VS-SRS, before surgery, and at last follow-up, respectively (mean follow-up, 6.9 years). Fifteen AVMs were cured after surgery. Ten patients had good outcomes at last follow-up (7 with mRS Score 0 or 1, and 3 with mRS Score 2). There were 2 deaths (both mRS Score 1 before treatment) and 4 patients with mRS Score 3 outcome (from mRS Scores 0, 1, and 2 [n = 2]).

Conclusions Volume-staged SRS can downgrade AVMs, transforming high-grade AVMs (initially considered inoperable) into operable AVMs with acceptable surgical risks. This treatment paradigm offers an alternative to conservative observation for young patients with unruptured AVMs and long life expectancy, where the risk of hemorrhage is substantial. Difficult AVMs were cured in 15 patients. Surgical morbidity associated with downgraded AVMs is reduced to that of postradiosurgical/preoperative supplemented Spetzler-Martin grades, not their initial AVM grades.

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Gamma Knife radiosurgery for meningiomas arising from the tentorium

Gamma Knife radiosurgery for meningiomas arising from the tentorium- a 22-year experienceJ Neurooncol (2015) 121:129–134

In order to evaluate long term clinical and imaging outcomes, the authors retrospectively reviewed our 22-year experience using stereotactic radiosurgery (SRS) for tentorial meningiomas.

Thirty-nine patients with tentorial meningiomas underwent SRS using various Gamma Knife technologies between 1988 and 2010. The most common presenting symptoms were headache, dizziness or disequilibrium, and ataxia. The median tumor volume was 4.6 cm3 (range 0.5–36.6 cm3) and the median radiation dose to the tumor margin was 14 Gy (range 8.9–18 Gy). The median follow-up period was 41 months (range 6–183 months).

At the last imaging follow-up, tumor volumes decreased in 22 patients (57 %), remained stable in 13 patients (33 %), and increased in 4 patients (10 %). The progression-free survival after SRS was 97 % at 1 year, and 92 % at 5 years. At the last clinical followup, 35 patients (90 %) showed no change in symptoms, 1 patient (2 %) showed improvement of their neurologic symptom, and 3 patients (8 %) demonstrated worsening symptoms. The rate of symptom worsening after SRS was 5 % at 1 year, and 10 % at 5 years. Asymptomatic peritumoral edema after SRS occurred in 2 patients (5 %). Symptomatic adverse radiation effect developed in 2 patients (5 %).

SRS for tentorial meningiomas provided long-term effective tumor control and a low risk of radiation related complications.

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Stereotactic radiosurgery for Spetzler-Martin Grade III arteriovenous malformations

Spetzler-Martin grade III AVMs

J Neurosurg 120:973–981, 2014

The purpose of this study was to define the outcomes and risks of stereotactic radiosurgery (SRS) for Spetzler-Martin (SM) Grade III arteriovenous malformations (AVMs).

Methods. Between 1987 and 2009, SRS was performed in 474 patients with SM Grade III AVMs. The AVMs were categorized by scoring the size (S), drainage (D), and location (L): IIIa was a small AVM (S1D1L1, N = 282); IIIb was a medium/deep AVM (S2D1L0, N = 44); and IIIc was a medium/eloquent AVM (S2D0L1, N = 148). The median target volume was 3.8 ml (range 0.1–26.3 ml) and the margin dose was 20 Gy (range 13–25 Gy). Eighty-one patients (17%) underwent prior embolization, and 58 (12%) underwent prior resection.

Results. At a mean follow-up of 89 months, the total obliteration rates documented by angiography or MRI for all SM Grade III AVMs increased from 48% at 3 years to 69% at 4 years, 72% at 5 years, and 77% at 10 years. The SM Grade IIIa AVMs were more likely to obliterate than other subgroups. The cumulative rate of hemorrhage was 2.3% at 1 year, 4.4% at 2 years, 5.5% at 3 years, 6.4% at 5 years, and 9% at 10 years. The SM Grade IIIb AVMs had a significantly higher cumulative rate of hemorrhage. Symptomatic adverse radiation effects were detected in 6%.

Conclusions. Treatment with SRS was an effective and relatively safe management option for SM Grade III AVMs. Although patients with residual AVMs remained at risk for hemorrhage during the latency interval, the cumulative 10-year 9% hemorrhage risk in this series may represent a significant reduction compared with the expected natural history.

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Radiosurgery for Spetzler-Martin Grade III arteriovenous malformations

Multimodality management of Spetzler-Martin Grade III arteriovenous malformations

J Neurosurg 120:959–969, 2014

Intracranial arteriovenous malformations (AVMs) are most commonly classified based on their Spetzler- Martin grades. Due to the composition of the Spetzler-Martin grading scale, Grade III AVMs are the most heterogeneous, comprising 4 distinct lesion subtypes. The management of this class of AVMs and the optimal treatment approach when intervention is indicated remain controversial. The authors report their experience with radiosurgery for the treatment of Grade III AVMs in a large cohort of patients.

Methods. All patients with Spetzler-Martin Grade III AVMs treated with radiosurgery at the University of Virginia over the 20-year span from 1989 to 2009 were identified. Patients who had less than 2 years of radiological follow-up and did not have evidence of complete obliteration during that period were excluded from the study, leaving 398 cases for analysis. The median patient age at treatment was 31 years. The most common presenting symptoms were hemorrhage (59%), seizure (20%), and headache (10%). The median AVM volume was 2.8 cm3, and the median prescription dose was 20 Gy. The median radiological and clinical follow-up intervals were 54 and 68 months, respectively. Univariate and multivariate Cox proportional hazards and logistic regression analysis were used to identify factors associated with obliteration, postradiosurgery radiation-induced changes (RIC), and favorable outcome.

Results. Complete AVM obliteration was observed in 69% of Grade III AVM cases at a median time of 46 months after radiosurgery. The actuarial obliteration rates at 3 and 5 years were 38% and 60%, respectively. The obliteration rate was higher in ruptured AVMs than in unruptured ones (p < 0.001). Additionally, the obliteration rate for Grade III AVMs with small size (< 3 cm diameter), deep venous drainage, and location in eloquent cortex was higher than for the other subtypes (p < 0.001). Preradiosurgery AVM rupture (p = 0.016), no preradiosurgery embolization (p = 0.003), increased prescription dose (p < 0.001), fewer isocenters (p = 0.006), and a single draining vein (p = 0.018) were independent predictors of obliteration. The annual risk of postradiosurgery hemorrhage during the latency period was 1.7%. Two patients (0.5%) died of hemorrhage during the radiosurgical latency period. The rates of symptomatic and permanent RIC were 12% and 4%, respectively. Absence of preradiosurgery AVM rupture (p < 0.001) and presence of a single draining vein (p < 0.001) were independent predictors of RIC. Favorable outcome was observed in 63% of patients. Independent predictors of favorable outcome were no preradiosurgery hemorrhage (p = 0.014), increased prescription dose (p < 0.001), fewer isocenters (p = 0.014), deep location (p = 0.014), single draining vein (p = 0.001), and lower Virginia radiosurgery AVM scale score (p = 0.016).

Conclusions. Radiosurgery for Spetzler-Martin Grade III AVMs yields relatively high rates of obliteration with a low rate of adverse procedural events. Small and ruptured lesions are more likely to become obliterated after radiosurgery than large and unruptured ones.

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Stereotactic radiosurgery for arteriovenous malformations of the cerebellum

Bowden et al

J Neurosurg 120:583–590, 2014

Arteriovenous malformations (AVMs) of the posterior fossa have an aggressive natural history and propensity for hemorrhage. Although the cerebellum accounts for the majority of the posterior fossa volume, there is a paucity of stereotactic radiosurgery (SRS) outcome data for AVMs of this region. The authors sought to evaluate the long-term outcomes and risks of cerebellar AVM radiosurgery.

Methods. This single-institution retrospective analysis reviewed the authors’ experience with Gamma Knife surgery during the period 1987–2007. During this time 64 patients (median age 47 years, range 8–75 years) underwent SRS for a cerebellar AVM. Forty-seven patients (73%) presented with an intracranial hemorrhage. The median target volume was 3.85 cm3 (range 0.2–12.5 cm3), and the median marginal dose was 21 Gy (range 15–25 Gy).

Results. Arteriovenous malformation obliteration was confirmed by MRI or angiography in 40 patients at a median follow-up of 73 months (range 4–255 months). The actuarial rates of total obliteration were 53% at 3 years, 69% at 4 years, and 76% at 5 and 10 years. Elevated obliteration rates were statistically higher in patients who underwent AVM SRS without prior embolization (p = 0.005). A smaller AVM volume was also associated with a higher rate of obliteration (p = 0.03). Four patients (6%) sustained a hemorrhage during the latency period and 3 died. The cumulative rates of AVM hemorrhage after SRS were 6% at 1, 5, and 10 years. This correlated with an overall annual hemorrhage rate of 2.0% during the latency interval. One patient experienced a hemorrhage 9 years after confirmed MRI and angiographic obliteration. A permanent neurological deficit due to adverse radiation effects developed in 1 patient (1.6%) and temporary complications were seen in 2 additional patients (3.1%).

Conclusions. Stereotactic radiosurgery proved to be most effective for patients with smaller and previously nonembolized cerebellar malformations. Hemorrhage during the latency period occurred at a rate of 2.0% per year until obliteration occurred.

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Long-term Outcomes After Gamma Knife Radiosurgery for Patients With a Nonfunctioning Pituitary Adenoma

Neurosurgery 69:284–293, 2011 DOI: 10.1227/NEU.0b013e31821bc44e

Nonfunctioning pituitary adenomas recur after microsurgery. Gamma Knife radiosurgery (GKRS) has been used to treat recurrent adenomas.

OBJECTIVE: To evaluate the long-term rates of tumor control and development of hypopituitarism in patients with nonfunctioning pituitary adenomas after GKRS.

METHODS: Forty-eight patients with a nonfunctioning pituitary adenoma treated between 1991 and 2004 at the University of Virginia were studied. All patients had more than 4 years of clinical and imaging follow-up.

RESULTS: All patients underwent follow-up imaging and endocrine evaluations, with a duration ranging from 50 to 215 months (median, 80.5 months) and 57 to 201 months (median, 95 months), respectively. New hormone deficiency after GKRS occurred in 19 of 48 patients (39%). Corticotropin/cortisol deficiency developed in 8% of patients, thyroid hormone deficiency in 20.8%, gonadotropin deficiency in 4.2%, growth hormone/insulin-like growth factor 1 in 16.7%, and diabetes insipidus in 2%. Panhypopituitarism including diabetes insipidus developed in 1 patient. Overall, control of tumor volume was 83%. Tumor volume decreased in 36 patients (75%), increased in 8 patients (17%), and was unchanged in 4 patients (8%). Tumor volumes greater than 5 mL at the time of GKRS were associated with a significantly greater rate of growth (P = .003) compared with an adenoma with a volume of 5 mL or less.

CONCLUSION: GKRS resulted in a high and durable rate of tumor control in patients with a nonfunctioning pituitary adenoma. A higher preoperative tumor volume was associated with an increased rate of tumor growth.

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Gamma Knife surgery of meningiomas located in the posterior fossa: factors predictive of outcome and remission

J Neurosurg 114:1399–1409, 2011. DOI: 10.3171/2010.11.JNS101193

Although numerous studies have analyzed the role of stereotactic radiosurgery for intracranial meningiomas, few studies have assessed outcomes of posterior fossa meningiomas after stereotactic radiosurgery. In this study, the authors evaluate the outcomes of posterior fossa meningiomas treated with Gamma Knife surgery (GKS). The authors also assess factors predictive of new postoperative neurological deficits and tumor progression.

Methods. A retrospective review was performed of a prospectively compiled database documenting the outcomes of 152 patients with posterior fossa meningiomas treated at the University of Virginia from 1990 to 2006. All patients had a minimum follow-up of 24 months. There were 30 males and 122 females, with a median age of 58 years (range 12–82 years). Seventy-five patients were treated with radiosurgery initially, and 77 patients were treated with GKS after resection. Patients were assessed clinically and radiographically at routine intervals following GKS. Factors predictive of new neurological deficit following GKS were assessed via univariate and multivariate analysis, and Kaplan-Meier analysis and Cox multivariate regression analysis were used to assess factors predictive of tumor progression.

Results. Patients had meningiomas centered over the tentorium (35 patients, 23%), cerebellopontine angle (43 patients, 28%), petroclival region (28 patients, 18%), petrous region (6 patients, 4%), and clivus (40 patients, 26%). The median follow-up was 7 years (range 2–16 years). The mean preradiosurgical tumor volume was 5.7 cm3 (range 0.3–33 cm3), and mean postradiosurgical tumor volume was 4.9 cm3 (range 0.1–33 cm3). At last follow-up, 55 patients (36%) displayed no change in tumor volume, 78 (51%) displayed a decrease in volume, and 19 (13%) displayed an increase in volume. Kaplan-Meier analysis demonstrated radiographic progression-free survival at 3, 5, and 10 years to be 98%, 96%, and 78%, respectively. In Cox multivariable analysis, pre-GKS covariates associated with tumor progression included age greater than 65 years (hazard ratio [HR] 3.24, 95% CI 1.12–9.37; p = 0.03) and a low dose to the tumor margin (HR 0.76, 95% CI 0.60–0.97; p = 0.03), and post-GKS covariates included shunt-dependent hydrocephalus (HR 25.0, 95% CI 3.72–100.0; p = 0.001). At last clinical follow-up, 139 patients (91%) demonstrated no change or improvement in their neurological condition, and 13 patients showed symptom deterioration (9%). In multivariate analysis, the only factors predictive of new or worsening symptoms were clival or petrous location (OR 4.0, 95% CI 1.1–13.7; p = 0.03).

Conclusions. Gamma Knife surgery offers an acceptable rate of tumor control for posterior fossa meningiomas and accomplishes this with a low incidence of neurological deficits. In patients selected for GKS, tumor progression is associated with age greater than 65 years and decreasing dose to the tumor margin. Clival- or petrous-based locations are predictive of an increased risk of new or worsening neurological deficit following GKS.

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Gamma Knife radiosurgery for larger-volume vestibular schwannomas

J Neurosurg 114:801–807, 2011.DOI: 10.3171/2010.8.JNS10674

Stereotactic radiosurgery (SRS) is an important management option for patients with small- and medium- sized vestibular schwannomas. To assess the potential role of SRS in larger tumors, the authors reviewed their recent experience.

Methods. Between 1994 and 2008, 65 patients with vestibular schwannomas between 3 and 4 cm in one extracanalicular maximum diameter (median tumor volume 9 ml) underwent Gamma Knife surgery. Seventeen patients (26%) had previously undergone resection.

Results. The median follow-up duration was 36 months (range 1–146 months). At the first planned imaging follow-up at 6 months, 5 tumors (8%) were slightly expanded, 53 (82%) were stable in size, and 7 (11%) were smaller. Two patients (3%) underwent resection within 6 months due to progressive symptoms. Two years later, with 63 tumors overall after the 2 post-SRS resections, 16 tumors (25%) had a volume reduction of more than 50%, 22 (35%) tumors had a volume reduction of 10–50%, 18 (29%) were stable in volume (volume change < 10%), and 7 (11%) had larger volumes (5 of the 7 patients underwent resection and 1 of the 7 underwent repeat SRS). Eighteen (82%) of 22 patients with serviceable hearing before SRS still had serviceable hearing after SRS more than 2 years later. Three patients (5%) developed symptomatic hydrocephalus and underwent placement of a ventriculoperitoneal shunt. In 4 patients (6%) trigeminal sensory dysfunction developed, and in 1 patient (2%) mild facial weakness (House-Brackmann Grade II) developed after SRS. In univariate analysis, patients who had a previous resection (p = 0.010), those with a tumor volume exceeding 10 ml (p = 0.05), and those with Koos Grade 4 tumors (p = 0.02) had less likelihood of tumor control after SRS.

Conclusions. Although microsurgical resection remains the primary management choice in patients with low comorbidities, most vestibular schwannomas with a maximum diameter less than 4 cm and without significant mass effect can be managed satisfactorily with Gamma Knife radiosurgery.

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Gamma Knife Surgery for Cavernous Hemangiomas in the Cavernous Sinus

Neurosurgery 67:611-616, 2010 DOI: 10.1227/01.NEU.0000378026.23116.E6

Cavernous hemangioma in the cavernous sinus (CS) is a rare vascular tumor. Direct microsurgical approach usually results in massive hemorrhage. Radiosurgery has emerged as a treatment alternative to microsurgery.

OBJECTIVE: To further investigate the role of Gamma Knife surgery (GKS) in treating CS hemangiomas.

METHODS: This was a retrospective analysis of 7 patients with CS hemangiomas treated by GKS between 1993 and 2008. Data from 84 CS meningiomas treated during the same period were also analyzed for comparison. The patients underwent follow-up magnetic resonance imaging at 6-month intervals. Data on clinical and imaging changes after radiosurgery were analyzed.

RESULTS: Six months after GKS, magnetic resonance imaging revealed an average of 72% tumor volume reduction (range, 56%-83%). After 1 year, tumor volume decreased 80% (range, 69%-90%) compared with the pre-GKS volume. Three patients had > 5 years of follow- up, which showed the tumor volume further decreased by 90% of the original size. The average tumor volume reduction was 82%. In contrast, tumor volume reduction of the 84 cavernous sinus meningiomas after GKS was only 29% (P < .001 by Mann-Whitney U test). Before treatment, 6 patients had various degrees of ophthalmoplegia. After GKS, 5 improved markedly within 6 months. Two patients who suffered from poor vision improved after radiosurgery.

CONCLUSION: GKS is an effective and safe treatment modality for CS hemangiomas with long-term treatment effect. Considering the high risks involved in microsurgery, GKS may serve as the primary treatment choice for CS hemangiomas.

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Repeat Gamma Knife Surgery for Incompletely Obliterated Cerebral Arteriovenous Malformations

Neurosurgery 67:55-64, 2010 DOI: 10.1227/01.NEU.0000370204.68711.AC

The causes of failure after an initial Gamma procedure were studied, along with imaging and clinical outcomes, in a series of 140 patients with cerebral arteriovenous malformations (AVMs) treated with repeat Gamma Knife surgery (GKS).

METHODS: Causes of initial treatment failure included inaccurate nidus definition in 14 patients, failure to fill part of the nidus as a result of hemodynamic factors in 16, recanalization of embolized AVM compartments in 6, and suboptimal dose (< 20 Gy) in 23. Nineteen patients had repeat GKS for subtotal obliteration of AVMs. In 62 patients, the AVM failed to obliterate despite correct target definition and adequate dose. At the time of retreatment, the nidus volume ranged from 0.1 to 6.9 cm3 (mean, 1.4 cm3), and the mean prescription dose was 20.3 Gy.

RESULTS: Repeat GKS yielded a total angiographic obliteration in 77 patients (55%) and subtotal obliteration in 9 (6.4%). In 38 patients (27.1%), the AVMs remained patent, and in 16 patients (11.4%), no flow voids were observed on magnetic resonance imaging. Clinically, 126 patients improved or remained stable, and 14 experienced deterioration (8 resulting from a rebleed, 2 caused by persistent arteriovenous shunting, and 4 related to radiationinduced changes).

CONCLUSION: By using repeat GKS, we achieved a 55% angiographic cure rate. Although radiation-induced changes as visualized on magnetic resonance imaging occurred in 48 patients (39%), only 4 patients (3.6%) developed permanent neurological deficits. These findings may be useful in deciding the management of AVMs in whom total obliteration after initial GKS was not achieved.

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Stereotactic radiosurgery for symptomatic solitary cerebral cavernous malformations considered high risk for resection

J Neurosurg 113:23–29, 2010. DOI: 10.3171/2010.1.JNS081626

A retrospective study was conducted to reassess the benefit and safety of stereotactic radiosurgery (SRS) in patients with solitary cerebral cavernous malformations (CCMs) that bleed repeatedly and are poor candidates for surgical removal.

Methods. Between 1988 and 2005 at the University of Pittsburgh, the authors performed SRS in 103 evaluable patients (57 males and 46 females) with solitary symptomatic CCMs. The mean patient age was 39.3 years. Ninetyeight percent of these patients had experienced 2 or more hemorrhages associated with new neurological deficits. Seventeen patients (16.5%) had undergone attempted resection before radiosurgery. Ninety-three CCMs were located in deep brain structures and 10 were in subcortical lobar areas of functional brain importance. The median malformation volume was 1.31 ml, and the median tumor margin dose was 16 Gy.

Results. The follow-up ranged from 2 to 20 years. The annual hemorrhage rate—that is, a new neurological deficit associated with imaging evidence of a new hemorrhage—before SRS was 32.5%. After SRS 22 hemorrhages were observed within 2 years (10.8% annual hemorrhage rate) and 4 hemorrhages were observed after 2 years (1.06% annual hemorrhage rate). The risk of hemorrhage from a CCM was significantly reduced after radiosurgery (p < 0.0001). Overall, new neurological deficits due to adverse radiation effects following SRS developed in 14 patients (13.5%), with most occurring early in our experience. Modifications in technique (treatment volume within the T2- weighted MR imaging–defined margin, use of MR imaging, and dose reduction for CCM in critical brainstem locations) further reduced risks after SRS.

Conclusions. Data in this study provide further evidence that SRS is a relatively safe procedure that reduces the rebleeding rate for CCMs located in high-surgical-risk areas of the brain.

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Tolerance of the Optic Apparatus in Single-Fraction Irradiation Using Stereotactic Radiosurgery: Evaluation in 100 Patients With Craniopharyngioma

Neurosurgery 66:688-695, 2010. DOI: 10.1227/01.NEU.0000367554.96981.26

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) cm3. 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 progressionfree 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.

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Retreatment of trigeminal neuralgia with Gamma Knife radiosurgery: is there an appropriate cumulative dose?

J Neurosurg 111:359–364, 2009


Trigeminal neuralgia (TN) is a disorder of the trigeminal nerve that results in intense episodic pain. Primary treatment with Gamma Knife surgery (GKS) is well established; however, a significant number of patients experience recurrence of TN over time. Repeat GKS can be performed, but the retreatment dose has not been well established. In this study, the authors present their institutional retreatment results and compare them with other series.

Methods
Between December 2003 and January 2006, 28 patients were treated at Tufts Medical Center with repeat GKS for recurrence of TN. All patients had been initially treated with GKS at this institution, and only those with significant pain improvement were offered retreatment. The maximum dose was prescribed using a single isocenter; the 4-mm collimator was used. The initial median GKS dose was 80 Gy, the median retreatment dose was 45 Gy, and the median cumulative dose was 125 Gy. The median time between GKS procedures was 18.1 months. Facial pain outcomes were defined using the Marseille scale. Excellent outcome was defined as no pain (with or without medications), and good outcome was defined as > 50% pain relief. Toxicity was categorized as none, mild, or bothersome. The median clinical follow-up after the second GKS was 19.7 months. Our clinical outcomes were compared with 8 previously reported retreatment series (including 1 abstract), both for rate of pain control and for rate of complications.

Results
Outcomes after the second GKS were excellent in 29% (8 patients), good in 32% (9), and poor in 39% (11). Four patients (14%) experienced no improvement after repeat GKS. Eight patients (29%) experienced new trigeminal nerve dysfunction, including numbness (11%), paresthesia (14%), dysesthesia (4%), taste alteration (11%), and bite weakness (4%). None of these were bothersome. No patient developed corneal numbness. Univariate analysis failed to reveal any significant predictors of pain control or complications.

Seven published peer-reviewed retreatment series and the authors’ data (total 215 patients) were analyzed. There was a cumulative dose-response relationship for both pain control (p = 0.04) and new trigeminal dysfunction (p = 0.08). Successful pain control was strongly correlated with development of new dysfunction (p = 0.02). A cumulative dose > 130 Gy was more likely to result in successful (> 50%) pain control, but was also more likely (> 20%) to result in development of new dysfunction.

Conclusions
Successful retreatment of patients in whom the initial GKS treatment fails is feasible. Patients who respond initially may be at a higher risk of retreatment-related complications. There appears to be a dose-response relationship for both pain control and development of new side effects. It is important to counsel and treat patients individually based on this dose-response relationship.

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