IVIg is Effective in Patient with Cyclophosphamide-Refractory Susac Syndrome
Ronak Patel1, Lauren Offerle1, Nicholas Lannen1
1Corewell Health – Grand Rapids / Michigan State University Neurology
Background:
Susac Syndrome (SuS) is an immune-mediated endotheliopathy causing occlusion of the microvessels in the brain, retina, and inner ear. It is characterized by a clinical triad of CNS dysfunction, branch retinal artery occlusion (BRAO), and sensorineural hearing loss. Only approximately five hundred cases of SuS are reported, and there no published prospective therapeutic studies. Expert-generated guidelines recommend high-dose intravenous methylprednisolone (IVMP), with consideration of steroid sparing agents such as intravenous immunoglobulin (IVIg) or mycophenolate mofetil. Cyclophosphamide and rituximab are utilized in disease breakthrough.
Design/Methods:
We present a 34-year-old woman with the complete SuS triad with severe headache, bilateral occlusive retinal vasculitis, and tinnitus. SuS was further evidenced by characteristic “snowball” T1 hypodensities of the corpus callosum on brain MRI.
Results:
Following right monocular vision loss, she was misdiagnosed with multiple sclerosis and treated with a three-day course of high dose IVMP before SuS was suspected due BRAO discovery. After two months, she was re-dosed with a five-day course of high dose IVMP and cyclophosphamide (750 mg/m2), but outpatient IVIg could not be authorized due to insurance denial. Despite cyclophosphamide and prednisone 60mg daily, she experienced worsening headaches and visual loss. The patient was admitted the following month, IVIg was administered (2g/kg split over 2 days), and rapidly improved clinically. Despite continued monthly maintenance dosing with cyclophosphamide (750 mg/m2), she worsened symptomatically. Due to continued insurance denial, two hospital admissions were required for IVIg treatments within four weeks of diagnosis. Patient was clinically responsive to both IVIg treatments.
Conclusions:
Our case highlights the importance of IVIg in the acute treatment of SuS; despite steroid therapy and cyclophosphamide, clinical decline ensued until IVIg was initiated. The use of IVIg this manner is not widely reported. Additional supportive cases could lead to easier patient access to IVIg for management of SuS.