Unusual disease that causes acute confusion may be underdiagnosed

Classical neurology textbooks do not list Susac syndrome as a possible diagnosis of acute confusional states. And Susac syndrome is often misdiagnosed early on as multiple sclerosis or a similar disorder called acute disseminated encephalomyelitis (ADEM).

Susac syndrome affects three times as many women as men, and has been seen in patients ranging in age from 9 to 72 years.

Susac syndrome was first described in 1979 by Dr. John Susac in the journal Neurology. It is believed to be an autoimmune disease, in which the immune system attacks endothelial cells that line blood vessels in the brain, inner ears and retinas. This causes the endothelial cells to swell up and partially or completely block blood flow to affected organs.

The Loyola authors describe two Susac syndrome patients who presented with acute confusion and abnormal MRIs and spinal fluid:

- A 32-year-old man was found by police on a highway in the wrong state. During the previous three weeks, he had displayed unusually violent behavior, incoherent speech and increasing inattention. He later developed hearing loss and blockages in the retinal arteries called branch retinal artery occlusions (BRAOs).

- A 57-year-old woman suffered confusion, forgetfulness, dizziness, blurred vision, fatigue, diminished hearing in the left ear, unsteady gait, facial weakness, numbness in her hands and inappropriate behavior.

Both patients recovered after being put on drugs to suppress their immune systems.

The authors propose that Susac syndrome be considered as a possible diagnosis in young patients with otherwise unexplained acute onset of confusion, along with abnormal spinal fluid tests and MRI results.