Superficial siderosis of the central nervous system despite successful treatment of cerebral arteriovenous malformation: A case report

We report a case of superficial siderosis (SS) of the central nervous system that developed approximately 8 years after the treatment of cerebral arteriovenous malformation (AVM). A 17-year-old boy was diagnosed with cerebral AVM in the right frontal lobe, which was treated with embolization and radiation therapy. Radiation-induced encephalopathy occurred 5 years later, and the lesion was resected. Although the patient could walk with a cane following the surgery and rehabilitation, he exhibited complete paresis of the left upper extremity. In the course of the next 9 years, he showed cognitive function decline, paresis of the lower right extremity, and the inability to walk. He also exhibited dysarthria and paresis of the right arm. Respiratory failure developed at age 39 years, necessitating mechanical ventilation. Cerebral angiography revealed no recurrence of cerebral AVM; however, brain and spinal magnetic resonance imaging revealed broad hemosiderin deposition, which is characteristic of SS, and the presence of a postoperative cyst that was suspected to be the bleeding source. While eliminating the source of the bleeding is considered the best line of treatment for SS, this was not pursued due to the patient's irreversible neurological condition. Thus, clinicians should consider SS as a differential diagnosis for patients that exhibit gradual and progressive neurological defects several years after successful AVM treatment. Keywords: Superficial siderosis, Radiation-induced encephalopathy, Arteriovenous malformation