Gamma Knife radiosurgery associated worsening of superficial siderosis due to a foramen magnum tumor - A case report.

Superficial siderosis (SS) of the brain results from a chronic iron toxicity due to repeated microscopic leakage of blood products into the subarachnoid space. We report on Gamma Knife Radiosurgery (GKRS) associated worsening of superficial siderosis in a patient with skull-base tumor. A 73 year-old male patient presented with clumsiness and gait ataxia and was diagnosed with foramen magnum meningioma. He was also noted to have superficial siderosis involving the mainly the infratentorial compartment. After a thorough evaluation of craniospinal axis, no other cause of bleeding was identified. Patient was treated with the GKRS. After GKRS, there was an initial radiological and clinical worsening of SS starting at 6 months and peaking at 2 years. The disease stabilized and showed mild reduction at 3 years. GKRS lead to an initial progression of superficial siderosis. However, over a longer period, tumor control and improvement of the siderosis was observed.