title: Gamma knife radiosurgery for arteriovenous malformations: long-term follow-up results focusing on complications occurring more than 5 years after irradiation.
abstract: The detailed long-term follow-up results of 40 patients treated for cerebral arteriovenous malformations with gamma knife radiosurgery are presented, with special reference to postradiosurgical complications that can develop many years after irradiation. The follow-up period after radiosurgery was 54 to 205 months, excluding one mortality, with a mean and a median of 106 and 97 months, respectively. One patient (2.5%) has, to date, refused all neuroimaging follow-up examinations. Complete nidus obliteration was angiographically confirmed in 26 patients (65%) between 1 and 5 years after radiosurgery. In the remaining 13 patients (32.5%), although significant shrinkage of each nidus was angiographically demonstrated, complete obliteration was not attained during a 3- to 7-year period of follow-up after radiosurgery. Among these 13 patients, 1 underwent surgical extirpation of the nidus and 5 underwent second courses of gamma knife radiosurgery between 3 and 6 years after initial treatment; in 3 of the 5 patients, complete nidus obliteration was angiographically confirmed between 1 and 3 years after the second course of radiosurgery. There were no radiation- or arteriovenous malformation-related mortalities. However, we did experience one angiography-related mortality. We also experienced one morbidity (probably caused by hemorrhagic stroke), which developed 5 years after 2-year postradiosurgical angiography had demonstrated complete obliteration, and three radiation-related morbidities, two of which (hemiparkinsonian syndrome and visual field disturbances caused by delayed cyst formation) occurred 5.5 and 7 years, respectively, after irradiation. Furthermore, we observed another two patients who, although asymptomatic to date, showed delayed cyst formation on magnetic resonance imaging 5 and 10 years after irradiation, respectively. In total, 3 (23%) of 13 patients who underwent computed tomography and/or magnetic resonance imaging more than 5 years after radiosurgery showed delayed cyst formation. In conclusion, long-term follow-up, particularly with the use of neuroimaging techniques, is necessary even after the treatment goal has been achieved.
authors.affiliation: Department of Neurosurgery, Tokyo Women's Medical College Dai-ni Hospital, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yamamoto
authors.forename: M
authors.initials: M
authors.lastname: Jimbo
authors.forename: M
authors.initials: M
authors.lastname: Hara
authors.forename: I
authors.initials: I
authors.lastname: Saito
authors.forename: K
authors.initials: K
authors.lastname: Mori
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000528:radiation effects; D002533:Cerebral Angiography; D002543:Cerebral Hemorrhage / Q000175:diagnosis / Q000209:etiology / Q000601:surgery; D002561:Cerebrovascular Disorders / Q000175:diagnosis / Q000209:etiology / Q000601:surgery; D002648:Child; D003560:Cysts / Q000175:diagnosis / Q000209:etiology / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000175:diagnosis / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis / Q000209:etiology* / Q000601:surgery; D011832:Radiation Injuries / Q000175:diagnosis / Q000209:etiology / Q000601:surgery; D016634:Radiosurgery; D012086:Reoperation; D014057:Tomography, X-Ray Computed