Symptoms of Susac Syndrome
Susac syndrome presents with a characteristic clinical triad of encephalopathy, branch retinal artery occlusions causing visual disturbances, and sensorineural hearing loss, though only 13-30% of patients exhibit all three features at initial presentation. 1, 2
Core Clinical Features
Neurological Manifestations (Encephalopathy)
- Headaches are a prominent feature accompanying the encephalopathy 2
- Multifocal neurologic deficits develop as part of the brain involvement 2
- Psychiatric symptoms, particularly paranoia, are characteristic 2
- Cognitive impairment can progress to dementia if untreated 1, 2
- Symptoms may include confusion, behavioral changes, and altered mental status 1
Visual Symptoms
- Branch retinal artery occlusions (BRAO) are the hallmark ophthalmologic finding 1, 2
- Visual symptoms may be asymptomatic initially, particularly when occlusions are peripheral 3
- Involvement is typically bilateral over time 3
- Gass plaques in retinal arterioles are almost always seen in the acute phase 4
- Visual field defects can occur depending on location of arterial occlusions 5
Auditory Symptoms
- Sensorineural hearing loss affecting the cochlea 2
- Initially may be unilateral but becomes bilateral in all cases 3
- Vertigo can accompany the hearing loss 2
- Hearing loss is typically irreversible and represents a major source of disability 2, 3
- Mean hearing loss severity is approximately 34 dB (range 15-70 dB) 3
Temporal Presentation Patterns
The complete triad is present at onset in only 13-30% of patients, making early diagnosis challenging. 1 The most common initial manifestation is central nervous system symptoms, followed by visual symptoms, then hearing disturbances 5. Inner ear involvement may occur with a mean delay of 11 months from onset 3.
Seasonal Pattern
There appears to be a seasonal clustering, with first symptoms occurring between April and September in 68% of patients 3.
Demographics
- Predominantly affects women aged 20-40 years, though the age range extends from 9 to 72 years 2
- Men are also affected but less commonly 2
Important Clinical Pitfalls
The variable and incomplete presentation at onset leads to frequent misdiagnosis, particularly confusion with multiple sclerosis, acute disseminated encephalomyelitis, and other neurological disorders 1, 2. The absence of the complete triad should not exclude the diagnosis if clinical suspicion exists based on characteristic MRI findings (central corpus callosum "snowball" lesions) or retinal fluorescein angiography showing arteriolar wall hyperfluorescence 6, 4.