Gass plaques and fluorescein leakage in Susac Syndrome

Susac Syndrome (SS) consists of the triad of encephalopathy, branch retinal artery occlusion, and hearing loss. It is an autoimmune endotheliopathy that primarily affects young women. Two funduscopic findings, Gass plaques (GP) and arteriolar wall hyperfluorescence (AWH), have recently been described and are not only useful in making the SS diagnosis but also point to the endothelium as the site of autoimmune injury. In this report we wish to raise awareness of GP and AWH with this disorder.

Four selected SS cases are presented with fundus photographs revealing GP. Fluorescein angiographic photographs are shown describing AWH.

GP are shown in several cases. These GP are unique in that they are yellow, sometimes refractile, and located distant from retinal arteriolar bifurcations unlike Hollenhorst plaques which are orange and located at retinal arteriolar bifurcations. Fluorescein angiography displays AWH of the retinal arterioles of patients with SS distant from affected vessels which has not been demonstrated in other retinal vasculitides.

Small punctuate yellow GP are almost unique to this disorder and their characteristic location and color should assist in confirming the diagnosis. Fluorescein angiography should be performed in all patients with an unexplained encephalopathy to look for the characteristic AWH pattern that occurs in this illness.