SUPERFICIAL SIDEROSIS

 35 yrs old patient, operated 3 yrs ago for a right frontoparietal high grade astrocytoma and underwent radiotherapy.

Axial GRE sequence: Thin hypointense rim noted on the cortical surface of both cerebral and cerebellar hemispheres and on the surface of brain stem- suggestive hemosiden deposition.



·        Superficial siderosis is the result of chronic and recurrent subarachnoid hemorrhage and the causes include:

1.     Postoperative

2.     Cerebral aneurysms

3.     Vascular malformations

4.     Cervical root avulsion

5.     Hemorrhagic neoplasms

·        CT is insensitive in detecting siderosis, but may reveal cerebral and cerebellar cortical atrophy that is associated with superficial siderosis.

·        The MR findings are dramatic, with the brain surface and cranial nerves outlined by a profound hypointense signal on T2 MR images.

·        T2 gradient echo (GRE) images are very sensitive to hemosiderin deposition and show blooming of the hypointense signal.

·        The source of recurrent bleed may sometimes be located in the spine which should always be screened if no cause is found by imaging of brain.

·        Hemosiderin is a neurotoxic agent that is responsible for neuronal and glial damage resulting especially in eighth cranial nerve damage and cerebellar atrophy that account for the characteristic clinical features of this disorder.

·        The most common clinical manifestations include bilateral sensorineural hearing loss and ataxia.

·        The other features include bilateral hemiparesis, bladderdisturbances, anosmia, dementia and headache.

·        The treatment is directed at the underlying cause.

Reference: Superficial siderosis, Neurology India | Sep-Oct 2009 | Vol 57