Symptomatic Radionecrosis Following Leksell Gamma Knife Radiosurgery: Results Of Surgical Treatment, Morphological And Immunohistochemical Studies





Keywords: complications, radiation injury, gamma knife, radiosurgery, resection

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Abstract

     Symptomatic radionecrosis rarely occurs after Gamma Knife (GK). It can be associated to severe neurological worsening due to dramatic perilesional edema resistant to corticosteroids. Resection of the MR-enhancing nodule allows prompt clinical improvement.
     We investigated various parameters potentially influencing this phenomenon.
     Post-GK surgery was performed in 37 patients: 26 metastases, 4 AVMs, 6 low-grade astrocytomas, 1 non-Hodgkin lymphoma. Histology showed necrosis in 20 patients (Group A) and neoplasia in 17 (Group B). Male/Female ratio was 14:6 (G.A) versus 9:8 (G.B) (p=0,05).
     The mean treated volume was 6.3 cc (G.A) versus 7.0 cc (G.B). Pre-surgery radiotherapy was performed in 11/20 cases (G.A) versus 7/17 (G.B).
     Mean GK-surgery interval was 64.2 months (G.A) versus 14.0 months (G.B) (p<0.05). Histopathology showed focal haemorrhage, neovascularization and/or reactive gliosis in 16/20, 12/20, 19/20 cases (G.A) and 2/17, 1/17, 8/17 cases (G.B) (p<0.0001, p<0.0019, p<0.018, respectively). Post-operative neurological improvement occurred in 14/20 patients (G.A) versus 10/17 (G.B). Patients still alive at last follow-up were 12/20 (G.A) and 4/17 (G.B). Median post-GK survival was 85.1 months (G.A) versus 37.9 months (G.B) (p<0.05). 
     This is a retrospective study.
     Our experience suggests that the surgical excision of the radionecrotic nodule alone — site of chronic bleeding and hypoxic phenomena — allows complete clinico-radiological resolution in these patients.
      An algorythm for management of such cases and the expression of hypoxia-inducible factor-1(, vascular endothelial growth factor, and glucose transporter-1 in the two groups will be presented.


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