Spectral domain optical coherence tomographic and angiographic findings in Susac syndrome

Abstract

 

Purpose

 

Susac syndrome consists of the triad of encephalopathy, hearing loss and visual deficits due to branch retinal artery occlusion. Our current knowledge about this rare and probably underdiagnosed disease mainly rests upon case reports and small case series, which often included less than 4 patients. We conducted this cross-sectional investigation to differentiate the ophthalmological features of Susac syndrome from other diseases, especially multiple sclerosis, because this is the most common misdiagnosis.

 

Methods

 

We analysed 11 patients (5 male/6 female, mean age 37 ± 11 years) with prediagnosed Susac syndrome from four centres in Germany. The clinical work-up included medical history, best corrected visual acuity (VA), contrast vision, slit-lamp examination and fundoscopy. In all patients visual field testing, measurement of peripapillary retinal nerve fibre layer thickness (RNFL) by spectral domain optical coherence tomography (SD-OCT) and fluorescein angiography (FA) were performed.

 

Results

 

The mean age at disease onset was 30 ± 10 years. Seven patients had a monocyclic course treated with immunosuppression, which was completed earlier. Three patients had a polycyclic or chronic course and one patient an active disease requiring immunosuppressive therapy at the time of examination. Visual acuity and contrast vision were in a normal range in all patients, while 7 showed visual field defects. Eight of 10 patients showed subclinical vascular anomalies with perivascular leakage and retinal arteriol occlusion on FA. One of 8 patients with retinal ischemia necessitated laser photocoagulation. The mean RNFL correlated inversely with the number of clock times with vascular anomalies and the number clock times of retinal ischemia. Additionally, the SD-OCT revealed a sectorial RNFL loss.

 

Conclusions

 

An important differential diagnosis of Susac syndrome is multiple sclerosis, which typically shows decreased VA and contrast vision combined with central scotoma, an overall reduced RNFL thickness but normal FA. In contrast in patients Susac syndrome we found normal VA and contrast vision, visual field defects corresponding to the retinal arteriol occlusion, a sectorally thinned RNFL and abnormalities on FA. Noteworthy, angiographic findings in Susac syndrome can resolve after immunosuppression.

 

Keywords: 612 neuro-ophthalmology: diagnosis • 688 retina