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

Antonio Nicolato1, Mario Ganau1, Claudio Ghimenton1, Roberto Foroni1, Francesco Lupidi1, Michele Longhi1, Giuseppe Kenneth Ricciardi1, Antonio De Simone2, Nicola Schiavo1, massimo a. gerosa3

1Department of Neurosurgery, University Hospital, Verona, Italy 2Vr, Italy 3University of Verona- Italy

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

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     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.


Project Roles:

A. Nicolato (), M. Ganau (), C. Ghimenton (), R. Foroni (), F. Lupidi (), M. Longhi (), G. Ricciardi (), A. De Simone (), N. Schiavo (), m. gerosa ()