Successful bevacizumab therapy for CNS radiation necrosis after stereotactic radiotherapy of an arteriovenous malformation

Background and methods: A radiation necrosis is a late sequela following CNS radiotherapy and offering limited therapeutic options. We describe benefits and side effects of bevacizumab in a case of radiation necrosis after therapy for arteriovenous malformation (AVM).

Results: After an unremarkable development, this 9 years old boy suffered from an acute ventricular hemorrhage. An AVM Spetzler II-III of the right hemisphere was identified. Following neurosurgery and consecutive rehabilitation treatment, activities of daily living were unimpaired. A few months later, at least partial embolisation of the AVM was possible, then stereotactic radiotherapy was performed with a cumulative dose of 55.0Gy (5 times 5.0Gy per week).

Twelve months later, a subacute left hemiparesis developed. Selective finger movements were lost. Circumduction gait, central facial palsy and hemianopsia were observed (GMFCS level II, MACS III, Radiation Therapy Oncology Group Score level III). MRI demontrated a radiation necrosis with extending edema and contralateral shift of the midline structures. Dexamethasone (4mg t.i.d) was promptly initiated and regression of the edema occured. With steroid therapy, a slow recovery of neurological function was seen. The dose of dexamethoson could not be lowered beneath 1mg t.i.d without recurring cerebral edema. Eventually, the boy complained of unacceptable side effects: an iatrogenic Cushing's syndrome, distended striae and skin ulcerations, arterial hypertension and increase of body mass index from 17 to 26kg/m².

Therefore, a trial of bevacizumab 7.5mg/kg b.w. every other week was performed for 16 weeks. The steroids could be completely withdrawn during this period. Until now MACS II was established.

Conclusion: To the best of our knowledge, this is the first pediatric report of a successful bevacizumab treatment for radiation necrosis after AVM radiotherapy.