Clinical History
Thirty-five year old Caucasian female presented with vertigo and right hearing loss. After medical treatment, her symptoms progressed to encephalopathy and an abnormal gate.
Imaging Findings
A thirty-five year old Caucasian female presented with vertigo and right hearing loss. She was diagnosed with otitis media clinically. After antibiotic treatment, two months later she developed encephalopathy. She began to forget friends and relatives identities. She underwent an MRI of the brain and a spinal tap. She was then treated with high dose steroids with a presumed diagnosis of multiple sclerosis (MS). About six weeks later, she developed an abnormal gate and was not improving from the initial symptoms. A follow-up MRI suggested Susac's Syndrome (SS). She was then treated IV immunoglobulin therapy and improved.
Discussion
Susac’s syndrome (SS) is a rare neurologic disorder [1-2]. The exact aetiology is still unknown but felt to most likely be secondary to microinfarction [1-2]. This disorder was characterized by John Susac as presenting with a clinical triad of hearing loss, encephalopathy, and visual changes [1-3]. Only a minority of patients present with the clinical triad [5]. Therefore, this diagnosis is difficult and somewhat elusive for clinicians [5].
Many times Susac's is misdiagnosed as multiple sclerosis [1,2,4,5.] This is secondary to its clinical overlap and white matter involvement on MRI. SS most characteristic radiographic finding is its involvement of the corpus callosum [1,2,4,5]. Typically the corpus lesions are in the central fibers (Fig 2); whereas MS is at the callosal septal interface [1-2]. SS also affects the grey matter, and MS does not. This fact also helps to differentiate it from other white matter diseases.
Susac's lesions have also been known to enhance after administration of gadolinium [1,2,4]. On occasion, the lesions may show restricted diffusion as well [1,2,4.] The whole brain has been reported to be involved [1,2,4]. SS lesions have been seen in the basal ganglia, thalami, cerebellum, brain stem and cerebrum well [1,2,4,5].
The most important reason for offering the diagnostic possibility of SS is to ensure proper treatment. If the diagnosis of MS is given, then the patient will most likely be treated with steroids. With the administration of steroids SS tends to progress. The proper treatment of SS involves combinations of IV immunoglobulins, plasmapharesis, cyclophosphamide, and or cyclosporine [5].
Differential Diagnosis List
