To the Editor: Susac's syndrome is a rare neurologic microangiopathy characterized by acute encephalopathy, branch retinal artery occlusion, and sensorineural hearing loss. Case studies have reported variable clinical presentations, which have included epileptic seizures and transient inverted vision. Although advances in neuroradiology suggest that MRI may aid in differential diagnosis, the variability in the presentation of encephalopathy continues to make diagnosis challenging.

Here, we present a patient with possible Susac's syndrome and a history of psychiatric symptoms who was referred for a neuropsychological evaluation after complaints of cognitive changes.

We present a 38-year-old, right-handed, single Caucasian woman, who, at the age of 19, developed sudden onset of partial loss of sight bilaterally, which resolved without neurologic evaluation or intervention. Her episode of vision loss was immediately followed by symptoms of depression, including general malaise, sadness, and suicidal ideation. Over the following year, the patient continued to experience depressive episodes and occasional periods of grandiosity and paranoia. She was diagnosed with bipolar disorder at age 21 and successfully treated with the lowest doses of aripiprazole and sertraline. Of note, she described a family history of significant psychiatric illness, including depression and behavioral disturbances. Her psychiatric symptoms remained relatively stable until age 30, when she attempted suicide. Several months after her suicide attempt, she experienced a new onset of physiologic and neurologic symptoms, including dizziness, mild hearing loss, dysarthria, and ataxia, as well as cognitive symptoms, including difficulty with navigation, reduced concentration, and impaired reading comprehension. She was referred to a neurologist, and neuroimaging revealed white-matter changes, prominent lateral ventricles, and cerebellum volume loss. The patient's condition was ultimately characterized as a Susac-like syndrome manifesting as current spastic ataxia and previous episodes of retinal vein occlusion and vertigo.

Upon neuropsychological examination at age 38, the patient reported that she continues to have motor and cognitive symptoms, although they have not progressed for the past 5 years. She also denied any recurrence of significant psychiatric symptoms since her suicide attempt at age 30. Neuropsychological assessment revealed moderate impairments in basic and complex attention, nonverbal learning, and aspects of executive functioning, with language and memory representing significant strengths of the cognitive profile. Emotionally, she endorsed minimal symptoms of depression and anxiety.

This case summary provides an example of a woman diagnosed with possible Susac's syndrome manifested as ataxic gait, dysarthria, and vision and hearing changes, with associated cognitive decline. Although the patient's significant psychiatric family history and age at psychiatric symptom onset is consistent with a diagnosis of bipolar disorder, her psychiatric symptoms should be considered a possible manifestation of encephalopathy related to Susac's syndrome, as the exacerbation of her psychiatric symptoms occurred in conjunction with her ophthalmologic and neurologic episodes. This case highlights the complicated nature of Susac-associated encephalopathy and how proper assessment and evaluation of the onset and course of the symptom profile may assist in earlier diagnosis of Susac's syndrome. Also, differentiation of psychiatric versus neurologic symptoms is imperative to treatment outcome, because treatment for Susac's syndrome is often via corticosteroids, which may exacerbate psychiatric symptoms, and treatment of psychiatric-presenting encephalopathic symptoms with psychotropic medications may delay proper treatment of Susac's syndrome.