Figure 1. Color fundus photographs and fluorescein angiograms. A, Color fundus photograph of the left eye shows yellow retinal arterial wall plaques. B, Higher magnification of the fundus photograph of the left eye shows yellow retinal arterial wall plaques (arrows). C, Fluorescein angiogram of the posterior pole of the left eye shows multiple areas of retinal arterial wall hyperfluorescence. D, Fluorescein angiogram of the nasal periphery shows areas of pruned retinal arterioles involving the nasal retinal periphery. E, Repeated color fundus photograph of the left eye 15 days after cessation of interferon beta-1-a treatment shows resolution of the yellow retinal arterial wall plaques. F, Higher magnification of the color fundus photograph of the left eye shows resolution of the yellow retinal arterial wall plaques. Repeated fluorescein angiograms of the left eye 15 days after cessation of interferon beta-1a treatment show complete resolution of all areas of retinal arterial wall hyperfluorescence (G) and reestablishment of arteriolar perfusion in the nasal retinal periphery (H).
Figure 2. Sagittal T1-weighted magnetic resonance imaging scan shows small round microinfarctions of the corpus callosum (arrows), consistent with the diagnosis of Susac syndrome.
Laird PW, Newman NJ, Yeh S. Exacerbation of Susac Syndrome Retinopathy by Interferon Beta-1a. Arch Ophthalmol. 2012;130(6):804-806. doi:10.1001/archophthalmol.2011.1841
Author Affiliations: Departments of Ophthalmology (Drs Laird, Newman, and Yeh), Neurology (Dr Newman), and Neurological Surgery (Dr Newman), Emory University School of Medicine, Atlanta, Georgia.
Susac syndrome features the triad of multiple branch retinal artery occlusions, hearing loss due to microinfarctions of the cochlea, and encephalopathy due to brain microangiopathy.1 Initial misdiagnosis as multiple sclerosis (MS) is not uncommon.1,2 Magnetic resonance imaging evidence of microinfarctions of the corpus callosum and multiple yellow retinal arterial wall plaques on fundus examination are helpful in differentiating this condition from demyelinating diseases.2,3
We describe a patient initially diagnosed as having MS who, after treatment with interferon beta-1a, was found to have multiple branch retinal artery occlusions. After interferon beta-1a cessation, rapid improvement of his visual fields and fluorescein angiographic appearance suggested that the interferon beta-1a may have exacerbated the retinal findings of Susac syndrome.
A 23-year-old white man experienced extremity numbness and paresthesia as well as headache. Magnetic resonance imaging showed periventricular white matter changes in the corpus callosum, which were attributed to demyelinating disease. One month later, he experienced a confusional episode. Three months later, he noted peripheral visual field loss in the left eye. Owing to concern for optic neuritis related to MS, he was treated with a short course of oral prednisone and began subcutaneous interferon beta-1a treatment. His visual symptoms improved, but 3 months later he developed peripheral vision loss in the right eye, resolving completely after a 1-week course of prednisone. Ten months after the initial visit, he experienced bilateral sequential hearing loss. Repeated magnetic resonance imaging findings of the brain were unchanged.
He had neuro-ophthalmic and retinal evaluations 15 months after beginning interferon beta-1a treatment, noting little improvement in his symptoms. Visual acuity was 20/20 OU. Funduscopic examination revealed punctate retinal hemorrhages along the superotemporal arcade, subtle sclerotic-appearing retinal arterioles, and yellow retinal arterial wall plaques (Figure 1A). Humphrey visual field showed bilateral nasal defects with a mean deviation of −7.87 dB OD and −12.0 dB OS. Fluorescein angiography showed peripheral branch retinal artery occlusions and retinal arteriolar wall hyperfluorescence (Figure 1C and D). Review of the prior magnetic resonance imaging findings showed small round microinfarctions in the corpus callosum (Figure 2). Formal audiology evaluation showed borderline mild sensorineural hearing loss in the right ear with excellent speech discrimination and moderate sensorineural hearing loss in the left ear with good speech discrimination. Impedance testing suggested normal pressure and good compliance in both ears. These findings were highly suggestive of Susac syndrome, and interferon beta-1a treatment was discontinued.
Two weeks after interferon beta-1a cessation, repeated fluorescein angiography showed remarkable improvement in the retinal arterial wall hyperfluorescence (Figure 1G and H). Continued improvement in the areas of peripheral retinal ischemia was observed at the 3-month follow-up, and functional improvement by static perimetry was also observed with mean deviations of −1.67 dB OD and −6.60 dB OS.
Our patient was initially misdiagnosed as having MS and treated with interferon beta-1a. Once his diagnosis of Susac syndrome was established and the interferon beta-1a treatment was stopped, he experienced rapid and dramatic improvement of the retinopathy, suggesting that the interferon beta-1a may have worsened the ocular manifestations of Susac syndrome. Interferon retinopathy is a well-known condition, usually manifesting with cotton-wool spots and retinal hemorrhages that resolve with medication cessation.4 Retinopathy developing specifically following subcutaneous interferon beta-1a treatment has been rarely reported.5 The multiple peripheral branch retinal artery occlusions and areas of retinal arteriolar wall hyperfluorescence in our patient are classic findings in Susac syndrome but would be very atypical manifestations of interferon retinopathy alone.
It is arguable that the angiographic findings and their resolution in our patient are consistent with the natural history of Susac syndrome, especially considering that the patient's visual symptoms began prior to his beginning treatment with interferon beta-1a. However, the temporal association of interferon beta-1a treatment cessation with the rapid resolution of the peripheral retinal ischemic process and improved visual fields suggests a causal and reversible association. Concurrent interferon beta-1a treatment for presumed MS may cause retinal vascular changes that may exacerbate or mimic Susac syndrome.
Correspondence: Dr Yeh, Department of Ophthalmology, Emory University School of Medicine, 1365B Clifton Rd NE, Ste 2400, Atlanta, GA 30322 (email@example.com).
Financial Disclosure: None reported.
Funding/Support: This work was supported in part by a departmental grant to the Department of Ophthalmology from Research to Prevent Blindness and by core grant P30-EY06360 to the Department of Ophthalmology from the National Institutes of Health. Dr Newman is a recipient of a Lew R. Wasserman Merit Award from Research to Prevent Blindness.