Susac syndrome (SS), also known as SICRET syndrome (small infarctions of cochlear, retinal and encephalic tissue), is a rare syndrome classically affecting females around the 2nd to 4th decades. It is thought to be caused by a microangiopathy of the brain retina and cochlear. It is typified by the clinical triad of acute or subacute encephalopathy, bilateral sensorineural hearing loss, and retinal arterial occlusions, although these may take up to 2 years to develop.
The condition more commonly affects females around the 2nd to 4th decades. Approximately three females are afflicted for every male case 9.
It consists of a clinical triad of:
- acute or subacute encephalopathy which could manifest in a broad spectrum of symptoms, such as: memory impairment, confusion, behavioral disturbances, ataxia, dysarthria, paranoid psychosis, and headaches 8
- sensorineural hearing loss at low and medium frequencies
- retinal arterial occlusions leading to scotomata and vision distortion
The primary pathology is a precapiliary arteriole microangiopathy of the brain, retina, and inner ear 9.
The brain study typically shows multiple, small lesions which are predominantly supratentorial. There is a predilection for the corpus callosum, though they can also be found in the cerebellum and midbrain. Callosal lesions typically involve the central fibers with relative sparing of the periphery 1.
Signal characteristics include:
- T1 C+ (Gd): lesions frequently enhance during the acute stage 1
- T2/FLAIR: lesions are high signal
Treatment and prognosis
Usually has a self limiting but fluctuating course. Some patients may have residual neurological sequelae.
History and etymology
Initially described by John O Susac et al in 1979 3.
Considerations on the basis of pure radiographic (MRI) appearances include:
- 1. Susac JO. Susac's syndrome. AJNR Am J Neuroradiol. 2004;25 (3): 351-2. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 2. Demir MK. Case 142: Susac syndrome. Radiology. 2009;250 (2): 598-602. doi:10.1148/radiol.2502051865 - Pubmed citation
- 3. Susac JO, Hardman JM, Selhorst JB. Microangiopathy of the brain and retina. Neurology. 1979;29 (3): 313-6. Neurology (abstract) - Pubmed citation
- 4. White ML, Zhang Y, Smoker WR. Evolution of lesions in Susac syndrome at serial MR imaging with diffusion-weighted imaging and apparent diffusion coefficient values. AJNR Am J Neuroradiol. 2004;25 (5): 706-13. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 5. Do TH, Fisch C, Evoy F. Susac syndrome: report of four cases and review of the literature. AJNR Am J Neuroradiol. 2004;25 (3): 382-8. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 6. Crawley BK, Close A, Canto C et-al. Susac's syndrome: intratympanic therapy for hearing loss and a review of the literature. Laryngoscope. 2009;119 (1): 141-4. doi:10.1002/lary.20040 - Pubmed citation
- 7. Gross M, Eliashar R. Update on Susac's syndrome. Curr. Opin. Neurol. 2005;18 (3): 311-4. Curr. Opin. Neurol. (link) - Pubmed citation
- 8. Saenz R, Quan AW, Magalhaes A et-al. MRI of Susac's syndrome. AJR Am J Roentgenol. 2005;184 (5): 1688-90. doi:10.2214/ajr.184.5.01841688 - Pubmed citation
- 9. Susac JO, Egan RA, Rennebohm RM, Lubow M. Susac's syndrome: 1975-2005 microangiopathy/autoimmune endotheliopathy. J Neurol Sci. 2007 Jun 15;257(1-2):270-2. Epub 2007 Feb 28. Pubmed citation