E-212 The evidence of diffuse axonal injury as an indicator of radiation necrosis and its implication in treatment strategy. (23rd July 2022)

• Record Type: Journal Article
• Authors: Mironov, A
• Is Part Of: Journal of neurointerventional surgery. Volume 14(2022)Supplement 1
• Page Start: A194
• Page End: A194
• Publication Date: 2022-07-23
• Subjects: Nervous system -- Surgery -- Periodicals; Cerebrovascular disease -- Surgery -- Periodicals; 617.48
• DOI: 10.1136/neurintsurg-2022-SNIS.323
• Languages: English
• ISSNs: 1759-8478

Abstract

Abstract : Purpose: To explore the significance of existing diffuse axonal injury with secondary demyelination (Wallerian degeneration) of the corticofugal fibers at the level of midbrain on MR imaging, in differentiating radiation injury versus tumor recurrence in patients previously treated for brain neoplasm, who present with new contrast-enhancing lesions at the site or vicinity of their primary tumor. Materials & Methods: The follow-up MR imaging of a cohort of 22 patients have been analyzed for a period of 12 years. All patients had been treated previously with surgery for hemispheric brain mass and consequently underwent radiation therapy and chemotherapy. All patients developed radiation necrosis and underwent serial follow-up MR imaging in different time sequences (6 to 15 follow-up) over a maximum period of 12 years. Results: On serial post-treatment imaging studies, development of intraparenchymal lesions occurred in all patients, ranging from 5 to 120 months after radiation. They became manifest as intensive bright peripheral and intra-focal contrast enhancement, and abnormal T2 - weighted signal with remarkable discrepancy between the extension of the lesions and the existing non-relevant mass affect. There were a broadly based bright intensive enhancement with festoon-like or facet-like configuration. It develops often centrifugal from the margin of the post-surgery brain damage and involves both the gyral surface and the subependymal periventricular space. Al cases showed a progressive atrophy of ipsilateral cerebral peduncle and an abnormal T2 - weighted signal, which developed as a late delayed feature, ranging from 15 to 120 months after the radiation. In the time of surgery, and respectively the first year after surgery, there were no signs of distant atrophy or signal abnormalities of the corticofugal fibers at the level of midbrain. This suggest a secondary neuroaxonal dystrophy, or demyelination secondary to axon degeneration (Wallerian degeneration), developed delayed-after the radiation therapy. Conclusion: X-irradiated white matter is more susceptible to partial demyelination than normal white matter and effects of loss of endothelial integrity after radiation has its most profound effect on white matter. The influence of radiation can act on the natural history of brain tumors by causing different morphological and metabolic changes over an unlimited interval after radiation therapy. The secondary diffuse axonal degeneration due to radiation-induced effects can lead to distant demyelination and atrophy of corticofugal long fibers at the level of midbrain. In cases with renewed growth of a mass at the site of previously treated brain tumor associated with contrast enhancement, and consequently raised issues of indication for and choices of treatment, the sign of Wallerian degeneration at the level of midbrain does indicate an existing radiation necrosis. Disclosures: A. Mironov: None.