Sunday 11 September 2011

Superficial Siderosis MRI

Axial Flair images of Brain shows diffuse atrophy marked in cerebellar hemispheres and vermis. Age related atrophy and ex vacuo dilatation of lateral ventricles.
T2 *GRE images reveals low signal intensity hemosiderin staining along tentorium and interhemispheric fissure, not obvious on any other sequence.

Imaging diagnosis : Superficial Siderosis.

Superficial Siderosis

A rare condition characterised by abnormal hemosiderin staining of sub arachonid space, may be diffuse or focal, commonly overlying cerebral and cerebellar convexity, basal cisterns, ventral surface of brain stem on T2*GRE, results from excessive and repetitive subarachonid bleed.
An associated staining along cranial nerves particularly i, ii and viii CNs.
May see an associated atrophy of cerebellar hemispheres and vermis, lepto meningeal thickening with enhancement. 
CT usually normal, may show faint hyper dense layering. 

Differential diagnosis is none, it has a pathognomonic appearace on MRI T2*GRE.
The issue is cause of bleed. In ~25% cases cause in not found.

Clinically common symptoms are ataxia, hearing loss, anosmia, dementia; in long standing cases adjacent brain parenchymal atrophy ensues with altered cognition.

Treatment directed towards finding and removing the cause of bleeding.
Iron chelating agents.

Reference: Teaching atlas of brain imaging: By Nancy J. Fischbein, William P. Dillon, A. James Barkovich : Dural and lepto meningeal processes, Case 65, page  231.

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