Plenary Oral Presentations - Macquarie University Hospital

16 th International Meeting of the Leksell Gamma Knife ® SocietyMarch 2012, Sydney, AustraliaVA-192New nidus found adjacent to the target site of AVM treatedwith Gamma Knife radiosurgery – Report of 3 cases1Do Hoon Kwon, 2 Byung Duk Kwun, 3 Jae Seung Ahn, 4 Do Hee Lee, 5 Hyun Jung Kim1Asan Medical Center, College of Medicine, Univ. of Ulsan, Seoul, Korea2Asan Medical Center3Asan Medical Center4Asan Medical Center5Asan Medical CenterObjective: The new nidus was rarely found adjacent to the resecting margin of nidus after surgicalresection of the AVM especially in the young age group. But the new nidus adjacent to the target siteof AVM treated with radiosurgery had not been reported yet. We reported and reviewed our caseexperiences retrospectively.Methods: The authors retrospectively analyzed their experience in 1,000 cases of AVMs treated withGamma Knife surgery during 20 years. Among them, 3 cases of new nidus were found adjacent tothe target site with an incidence rate of 0.3%. No patient had been treated with embolization beforeradiosurgery. All patent had a history of ICH before or after reradiosurgery.Results: First patient was a 9 year old boy who treated with Gamma Knife for left occipital AVM onemonth after ICH. Treated volume was 600 cumm and 25Gy was irradiated to the margin of the nidus.Thirty one months after radiosurgery, the patient had have 2nd radiosurgery for the new nidus whichwas found adjacent to the target site, treated volume was 900 cumm. Second patient was a 9 yearold boy treated with Gamma Knife for the small AVM located in the cerebellar vermis 1 month afterbleeding. Five years after radiosurgery, he had rebleeding and retreated to the same nidus with GammaKnife 2 month after rebleeding. Six years after 2nd treatment, he had a new nidus adjacent to thetarget site and the volume was increased from 400 cumm (2nd treated volume) to 2,800 cumm. Hehad have 3rd radiosurgery for this new nidus. Third patient was a 33 year old man who treated withradiosurgery for the incidentally detected cerebellar AVM, the nidus volume was 1,100 cumm and 20Gy was irradiated to the nidus. Three years after radiosurgery, patient had cerebellar ICH and newnidus was found adjacent to the target site and 2nd radiosurgery was performed, the nidus volumewas 500 cumm.Conclusions: The new nidus might be developed adjacent to the target site in the treatment of AVMwith radiosurgery, but the incidence was very rare.Key words: nidus, AVM, radiosurgery80