Long-term outcome in Susac syndrome

Susac syndrome is characterized by the clinical triad of encephalopathy, heating loss, and retinal artery branch occlusions, mostly in young women. To our knowledge, long-term outcome and impact of pregnancy have not been specifically addressed. We report a series of 9 patients (7 female, 2 male) followed at the same institution, with special emphasis on clinical outcome including pregnancy and long-term sequelae. Clinical, brain magnetic resonance imaging (MRI), funduscopy, retinal angiography, and audiogram data were recorded every 3-12 months. We also analyzed the 92 previously reported cases of Susac syndrome. Mean follow-up was 6.4 years. Age at onset was 30.4 years. The first symptom occurred between April and September in 7 of 9 patients in the current study, and in 68% of all patients. The complete triad at onset was clinically obvious in only 1 of 9 patients. Brain involvement was heralded by headache and symptoms of encephalopathy. Cerebrospinal fluid was abnormal in 5 patients showing pleocytosis (mean, 24.6; range, 6-85 cells/mL) and elevated protein level (mean, 210; range, 113-365 mg/dL). Over time, quantitative brain MRI analysis showed that the number of lesions diminished and did not parallel clinical flares, and MRI never normalized. At the end of follow-up, no patient had severe impairment, and all but 1 returned to work. Inner ear involvement was present at onset in 2 patients and occurred in others with a mean delay of 11 months. Initially unilateral in 3, it became bilateral in all. Mean hearing loss was 34 dB (range, 15-70 dB). Hearing loss never improved, either spontaneously or under treatment. The eye was involved at onset in 8 patients, and after 3 years in 1. All had multiple bilateral retinal artery branch occlusions and/or dye leakage with hyperfluorescence of the arterial wall on fluorescein angiography. Over time, angiography normalized in 3 patients. In others, it was still abnormal at the end of follow-up (range, 1.5-10 yr). On late findings, fluorescein leakage was more frequent than true arterial occlusion. Eye involvement was mostly asymptomatic, unilateral, peripheral, and resumed spontaneously to remit in other sites over time. Corticosteroids were efficient to treat encephalopathy, with relapses occurring when the dosage was tapered. Steroid treatment did not improve hearing loss or prevent new retinal arteriolar occlusions. Anticoagulation had a role in treating encephalopathy and retinal arteriolar occlusions. Three patients had 4 pregnancies. Two pregnancies needed induced abortion. One pregnancy was uneventful. One pregnancy was complicated with Susac disease flare in the early postpartum period. In conclusion, at the end of follow-up, most patients had returned to work and none had severe impairment. Pregnancy may affect the course of Susac syndrome, with relapse of encephalopathy postpartum. Our main finding was that the course of Susac syndrome is not self-limited as previously thought, since isolated retinal arteriolar involvement may occur as a very late manifestation.