Gass plaques and fluorescein leakage in Susac Syndrome,☆☆

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Abstract

Introduction

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.

Methods

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

Results

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.

Conclusion

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.

Introduction

Susac Syndrome (SS) consists of encephalopathy, branch retinal artery occlusions, and hearing loss and affects women more than men [1], [2]. The complete triad may not be present at initial presentation. Headaches, often migrainous, are usually present including bilateral long tract findings, roaring tinnitus, vertigo, and bizarre personality changes. Magnetic resonance imaging that accompanies the encephalopathic SS patient always shows involvement of the corpus callosum and often strikingly [3]. Any part of the brain may be involved including deep grey matter lesions and leptomeningeal enhancement [3]. This imaging triad has been helpful in establishing the diagnosis at an early stage to allow for early, aggressive treatment.

Two additional and helpful funduscopic findings were recently described in this disorder. The first, the retinal arterial wall plaque (RAWP) now known as GP, originally was described by J. Don Gass in idiopathic branch retinal artery occlusions, now believed to be a form fruste of SS, and in a number of other rare retinal disorders [4], [5], [6]. After our initial description of GP in SS [7], we have found this plaque in a number of SS patients evaluated henceforth.

The second finding is an unusual leakage pattern of arterial wall hyperfluorescence (AWH) on fluorescein angiography (FA), a routine test used for a variety of ophthalmological complaints. Several reports have documented AWH of vessels not necessarily located near the branch retinal artery occlusion (BRAO) that occurs in patients with SS [8], [9]. There is a single report of a young patient who demonstrated AWH five days prior to the onset of a BRAO [10] plus another patient with SS with AWH that was treated with tacrolimus and avoided the onset of BRAO and enjoyed resolution of the AWH [11]. The purpose of this report is to demonstrate these two ophthalmic findings and raise awareness of them to the neurologic practitioner.

Section snippets

Methods

This is a retrospective, multi-center observational study documenting patients with GP and AWH of retinal vessels.

Case 1

A 35 year old woman developed severe headaches, numbness in her fingertips, episodic vision loss, and trouble speaking. Two months after onset she developed permanent partial vision loss in her left eye. Her right fundus appeared normal with the exception of two small yellow refractile GP, one at a retinal arteriolar bifurcation and another more distal to it (Fig. 1A). Her left fundus showed a swollen pallid retina inferior and temporal to the fovea consistent with a BRAO (Fig. 1B). An MRI scan

Discussion

Gass and coworkers were the first to describe multiple yellow GP that may simulate emboli in six of nine patients with idiopathic BRAO and he described them in other disorders that cause focal damage to the arterial wall [4], [5], [6], [12]. Gass attributed GP to atheromatous deposits caused by slow extravasation of blood lipids into the arterial wall at the sites of arterial wall damage. Unlike Fisher platelet–fibrin emboli (gray-white), Hollenhorst cholesterol plaques (orange and refractile),

Acknowledgment

The authors thank Robert Daroff for critical review of the manuscript.

References (13)

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This study conformed to the protocol of our Institutional Review Board and did not require approval by our IRB.

☆☆

This report is being submitted in conjunction with another report authored by Susac, Rennebohm, Egan, and Daroff titled “Susac Syndrome — Update.”

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