Triple Threat: Three Common Symptoms Add Up to One Rare Condition

Michelle E. Grady

March 24, 2021

When a 39-year-old previously healthy woman with blurred vision, hearing loss, and migraine presented to the emergency department (ED) at St. Michael's Hospital in Toronto, Canada, Sanskriti Sasikumar, MD, knew a multidisciplinary approach was needed to diagnose this unusual case.

The patient told Sasikumar, one of the first clinicians to see her, that she came to the hospital on the advice of her family doctor. For the past 3 weeks, she said, she hadn't felt like herself.

She'd been experiencing headaches, numbness in her fingers and around her mouth, blurred vision in both eyes, and hearing loss. Her husband reported that she'd recently developed apathy, which raised a red flag for Sasikumar.

When patients experience a sudden personality shift, "it's unusual, and we begin to think of encephalopathy," Sasikumar tells Medscape Medical News.

The case was published online November 24 in Neurology.

"Cotton Wool" Spots

To investigate, clinicians took a detailed history, tested the patient's cognitive function, conducted an audiogram and a dilated fundus exam, and performed an MRI of the brain and upper spinal cord.

Although the patient denied experiencing cognitive deficits, she scored 20 out of 30 on the Montreal Cognitive Assessment, indicating mild impairment.

The audiogram showed low-frequency hearing loss, and the eye exam revealed two "cotton wool" spots in the left eye and one in the right eye, identified as branch retinal artery occlusions.

MRI results, says Sasikumar, were "very abnormal, which surprised us, given how [cognitively] functional she was when we first saw her." Imaging revealed multiple "well-circumscribed" lesions in the thalamus, the corpus callosum, and the brain stem. "It was a very dramatic thing to see," Sasikumar adds.

These lesions together with the patient's other symptoms led the team to consider a diagnosis of Susac syndrome, a rare autoimmune disease with three defining characteristics — encephalopathy, branch retinal artery occlusion, and hearing loss.

Susac syndrome frequently presents as headache that progresses to impaired brain function, depending on the location of the lesions. It causes inflammation of the smaller blood vessels, which in turn blocks blood flow to the ears and eyes, causing hearing loss and visual disturbance.

Differential diagnoses considered by the team included demyelination, such as occurs with multiple sclerosis (MS) and other inflammatory disorders; lymphoma; and multiple infarcts from vasculitis.

Rare, Underreported

Orphanet, a website describing rare diseases and orphan drugs, estimates that as of 2020, more than 500 cases of Susac syndrome had been reported worldwide. The National Organization for Rare Disorders says it is likely that the condition is underreported, in part because it may be misdiagnosed as atypical MS.

"It's one of those rare syndromes that we're always taught about, but it's not something that a lot of people see in their career. We were amazed by how high functioning she seemed, given her MRI," says Sasikumar.

Sasikumar notes that once they discovered the spinal cord inflammation, which isn't typical of the syndrome, it was imperative that they rule out other diagnoses.

The team performed a lumbar puncture and routine bloodwork as part of a broad series of investigations. A CT scan was performed for cancer screening.

"We had our colleagues in ophthalmology, infectious diseases, and rheumatology on the case, given the multiorgan involvement," says Sasikumar.

The clinicians ruled out other conditions and were able to count this among the very few reported cases of Susac syndrome with cervical spinal cord inflammation, she says.

Once they had a firm diagnosis, the patient was treated with a 5-day course of intravenous corticosteroids together with intravenous immunoglobulin (IVIG) to pack a bigger therapeutic punch, says Sasikumar.

Within days of treatment, headache frequency and severity improved. At discharge, the patient's cognition had further improved, and over the following months, visual distortion became infrequent, but her hearing loss persisted.

"Flying Blind"

After IV therapy, the patient's regimen was transitioned to prednisone for 1 month. The plan was to slowly taper the dose over the following months. Treatment with mycophenolate mofetil titrated to 1 g twice daily was also initiated, and she received maintenance IVIG therapy every 5 to 6 weeks.

It was difficult for the team to decide on the specific disease-modifying agents because there is no consensus in the literature about what to use. "We were flying blind," says Sasikumar. Drawing on the expertise of a multidisciplinary team made all the difference with respect to treatment decisions, she adds.

"We were able to pick up on it early. Often when people present with this condition, they're already very confused and have a lot of behavioral problems and focal symptoms, like weakness or numbness or more obvious findings," she says.

The patient was discharged from the hospital 3 weeks after her initial presentation to the ED and continues to improve, says Sasikumar.

Neurology. Published online November 24, 2020. Full text

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