2026 American Academy of Neurology Abstract Website

Objective:

To characterize the clinical, radiological, and therapeutic features of rare complications of radiotherapy (RT), radiation necrosis (RN) and radiation myelopathy (RM) occurring beyond the targeted field.

Background:

RN and RM are delayed RT complications, typically confined to high-dose regions. Rare occurrences beyond the targeted field present diagnostic and therapeutic challenges, particularly in patients with complex neuro-oncologic histories.

Design/Methods:

Single-institution retrospective case series of five patients with RN or RM beyond the targeted field, including demographics, primary malignancy, radiation dose and technique, clinical presentation, imaging and management.

Results:

Five patients (3 female, 2 male; median age 55 years, range 38-70) developed these complications.

Brain lesions: Two patients received proton therapy for skull base malignancies -nasopharyngeal (72 Gy/36 fractions) and maxillary sinus carcinoma (70 Gy/33 fractions). RN developed 18-30 months post-RT with cognitive decline, aphasia, and headaches. Imaging demonstrated bitemporal necrosis in one patient and left temporal necrosis in the other. Both received corticosteroids with partial improvement. The first patient received one dose of bevacizumab with limited response and underwent surgery; the other continues bevacizumab with response pending.

Spinal lesions: Three patients developed thoracic RM (20 Gy/5 fractions via IMRT or 3D-CRT) for osseous metastases from lung cancer, breast cancer, or multiple myeloma. Symptoms developed 10-14 months post-RT, including lower extremity weakness, sensory loss, and autonomic dysfunction. Management included corticosteroids, bevacizumab, hyperbaric oxygen, and physical therapy. Two patients developed deep vein thrombosis after bevacizumab, but both had additional risk factors including concurrent thrombogenic therapy, active malignancy, and limited mobility due to myelopathy. Radiographic improvement was common, with clinical outcomes ranged from partial recovery to persistent deficits.

Conclusions:

RN and RM may occur outside high-dose regions even years after RT. Recognizing these patterns is essential to guide therapy, and optimize outcomes. Multidisciplinary management and individualized follow-up are essential, and further research is required to refine treatment strategies.