Gamma Knife

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Dinca, Eduard B., Patricia de Lacy, John Yianni, Jeremy Rowe, Matthias W. R. Radatz, Daniel Preoţiuc-Pietro, and Andras A. Kemeny. "Gamma Knife surgery for pediatric arteriovenous malformations: a 25-year retrospective study." Journal of Neurosurgery: Pediatrics 10 (2012): 445-450. AbstractWebsite

The authors present their 25-year experience in treating pediatric arteriovenous malformations (AVMs) to allow comparisons with other historic studies and data in adults.

Data were collected from a prospectively maintained departmental database selected for age and supplemented by case note review and telephone interviews as appropriate.

Three hundred sixty-three patients, ages 1–16 years (mean ± SD, 12 ± 3.2 years), underwent 410 treatments; 4 had planned 2-stage treatments and 43 were retreated subsequent to an initial partial response. Fifty-eight percent received general anesthesia for the procedure. Sixteen percent had previously undergone embolization. The most common presenting symptoms were as follows: hemorrhage (80.2%), epilepsy (8.3%; overall seizure prevalence 19.9%), and migrainous headaches (6.3%). Only 0.28% of the AVMs were incidental findings. The mean lesion volume was 3.75 ± 5.3 cm3 (range 0.01–32.8 cm3), with a median Spetzler-Martin grade of III (range I–V). The mean peripheral (therapeutic) dose was 22.7 ± 2.3 Gy (range 15–25 Gy), corresponding to a mean maximum dose of 43.6 ± 6 Gy (range 25–51.4 Gy).

The obliteration rate was 71.3% in patients who received one treatment and 62.5% for retreated patients, with a mean obliteration time of 32.4 and 79.6 months, respectively. The overall obliteration rate was 82.7%. No follow-up data are as yet available for the 4 patients who underwent the staged treatments. Only 4 patients received peripheral doses below 20 Gy, and the AVM was obliterated in 3 of these patients. The other patients received 20, 22.5, or 25 Gy and had obliteration rates of 82.6%, 77.7%, and 86.3%, respectively. The bleeding rate postradiosurgery was 2.2%, and the cumulative complication rate was 3.6%, with radionecrosis being the most common complication (1.1%).

Surprisingly, there was no correlation (p = 0.43) between outcome and radiosurgical dose when that dose was between 20 and 25 Gy, thus suggesting that the lower of these 2 doses may be effective. Radiosurgery for pediatric AVM is safe and effective.

Dinca, Eduard, John Yianni, Jeremy Rowe, Matthias Radatz, Daniel Preoţiuc-Pietro, Paul Rundle, Ian Rennie, and Andras Kemeny. "Survival and complications following Gamma Knife radiosurgery or enucleation for ocular melanoma: a 20-year experience." Acta Neurochirurgica 154 (2012): 605-610. AbstractWebsite


We present our experience in treating ocular melanoma at the National Centre for Stereotactic Radiosurgery in Sheffield, UK over the last 20 years.


We analysed 170 patients treated with Gamma Knife radiosurgery, recorded the evolution of visual acuity and complication rates, and compared their survival with 620 patients treated with eye enucleation. Different peripheral doses (using the 50% therapeutic isodose) were employed: 50-70 Gy for 24 patients, 45 Gy for 71 patients, 35 Gy for 62 patients.


There was no significant difference in survival between the 35-Gy, 45-Gy and 50– to 70-Gy groups when compared between themselves (p = 0.168) and with the enucleation group (p = 0.454). The 5-year survival rates were: 64% for 35 Gy, 62.71% for 45 Gy, 63.6% for 50–70 Gy and 65.2% for enucleated patients. Clinical variables influencing survival for radiosurgery patients were tumour volume (p = 0.014) and location (median 66.4 vs 37.36 months for juxtapapillary vs peripheral tumours, respectively; p = 0.001), while age and gender did not prove significant. Regarding complications, using 35 Gy led to more than a 50% decrease, when compared with the 45-Gy dose, in the incidence of cataract, glaucoma and retinal detachment. Retinopathy, optic neuropathy and vitreous haemorrhage were not significantly influenced. Blindness decreased dramatically from 83.7% for 45 Gy to 31.4% for 35 Gy (p = 0.006), as well as post-radiosurgery enucleation: 23.9% for 45 Gy vs 6.45% for 35 Gy (p = 0.018). Visual acuity, recorded up to 5 years post-radiosurgery, was significantly better preserved for 35 Gy than for 45 Gy (p = 0.0003).

Using 35 Gy led to a dramatic decrease in complications, vision loss and salvage enucleation, while not compromising patient survival.