Long-term results of radiosurgery for arteriovenous malformation: Neurodiagnostic imaging and histological studies of angiographically confirmed nidus obliteration

Hemorrhagic vestibular schwannoma: an unusual clinical entity

“…The role radiosurgery may play in treating hemorrhagic vestibular schwannomas is difficult to predict. Although radiosurgery appears to be effective in treating highly vascular lesions such as hemangioblastomas [13] or arteriovenous malformations, [15,17] its role in the treatment of many other lesions still needs to be defined. [5,8] We advocate surgical resection of these hemorrhagic tumors by means of either a suboccipital or a translabyrinthine approach.…”

WITHDRAWN: Predictors for complete obliteration of arteriovenous malformations following stereotactic radiosurgery

“…Radiosurgery is being used more frequently, particularly in patients with surgically inaccessible lesions. Radiosurgery has been shown to be a low risk procedure that is associated with high obliteration rates [6][7][8]. The primary aim of radiosurgery is to prevent hemorrhage by achieving complete AVM obliteration.…”

Hemorrhage from Arteriovenous Malformation Following Gamma Knife Radiosurgery: Pathophysiology of Rupture Early in the Latency Period

“…(Fajardo and Berthrong 1988;Schneider, Eberhard, and Steiner 1997;Tu et al 2006) A decrease in blood flow through AVMs, which is consistent with decreased luminal diameter due to intimal thickening, has been demonstrated on magnetic resonance (MR) imaging and angiography within a few months following radiosurgery. (Lunsford et al 1991;Yamamoto et al 1992) Arteriovenous malformations treated with radiosurgery may completely radiographically obliterate as early as a few months or more than 8 years after SRS, (Lunsford et al 1991;Yen et al 2007) and persistence of subtotal obliteration is documented during follow-up periods as great as 14 years after radiosurgery. (Yen et al 2007) The vaso-occlusive effects of SRS, as demonstrated on MR imaging or angiography, progress slowly and heterogeneously, generally reaching a maximum at 1 to 3 years postradiosurgery.…”

“…The mechanisms of vascular obliteration after stereotactic radiosurgery are not completely understood, (O'Connor and Mayberg 2000) but several histological and ultrastructural studies have helped to elucidate the physiological basis. (Adams 1991;Chang et al 1997;Schneider, Eberhard, and Steiner 1997;Szeifert et al 1997;Szeifert, Major, and Kemeny 2005;Tu et al 2006;Yamamoto et al 1992) Focused irradiation causes damage to endothelial cells and induces the subsequent proliferation of smooth muscle cells, fibroblasts, and myofibroblasts in the subendothelial layer. The elaboration of collagenous extracellular matrix in the intimal layer follows, leading to progressive hyalinization and thickening of the intimal layer, stenosis of the irradiated vessels, and complete vessel occlusion and nidal obliteration.…”

“…(Colombo et al 1994;Fabrikant et al 1992;Steinberg et al 1990) There is also evidence that a risk of hemorrhage persists even after radiographic obliteration of the AVM. (Izawa et al 2005;Lindqvist et al 2000;Matsumoto et al 2006;Shin et al 2005;Yamamoto et al 1992;Prat et al 2009) Hemorrhage in the early period following SRS is a rare occurrence, with few reports in the literature (Table 1). In the 30-day period following SRS, most reported cases of postradiosurgery hemorrhage within 72 hours of radiosurgery occurred in patients with irradiated tumors.…”