Optic neuritis may be sign of multiple sclerosis
My daughter, my oldest baby, just turned 21. Six weeks after the joy of her birth came a not so pleasant gift: my diagnosis of multiple sclerosis. Eighteen months later she was an active toddler, trucking around the house like only a 1 1/2-year-old can. I began to notice pain in my right eye. It was annoying, but I didn’t pay much attention – probably just a weird headache, I thought.
Only, it lingered. When I put pressure on the eye, or moved it, it hurt. I called my neurologist. “Cover up your left eye,” he told me. “See if you can read with your right eye.” I couldn’t. To say I was freaked out is the understatement of this and the last century. It was like someone had pulled gauze over my eye – I could make out shapes and colors but they were washed out, desaturated. I had optic neuritis.
Optic neuritis is a common symptom of multiple sclerosis, and, as in my case, it usually affects only one eye. Optic neuritis occurs at some time in the course of the disease in 50 percent of people with MS. It is the first symptom in 15 to 20 percent of MS patients. In a large, multicenter trial called the Optic Neuritis Treatment Trial (ONTT), after follow-up for 10 years, 38 percent of patients with a first episode of optic neuritis were later diagnosed with MS.
Optic neuritis is inflammation of the optic nerve. The nerve connects the eye to the part of the brain that processes visual information. Reacting to the influx of inflammatory white blood cells and the chemicals they secrete, the optic nerve swells. The swelling interferes with the travel of nerve signals from the eye to the brain. The loss of vision comes from the disrupted nerve signals. The pain comes from the inflammation and all those weird chemicals.
In MS, the inflammation is caused by the body’s own immune system turning on one of its most precious components, the myelin sheath that protects the nerves of the brain and spinal cord like the rubber on an electrical cord protects the wires within.
MS is not the only cause of optic neuritis, but it is the most common. Other autoimmune diseases, as well as infectious diseases like HIV, Lyme disease, syphilis and even sinusitis can have optic neuritis as a symptom. In older folks, the optic neuritis may result from interruption of blood flow to part of the optic nerve.
Rarely, a tumor may be the cause. But most of the time, a cause is never found. Visual acuity usually returns to baseline, although, as in my case, subtle symptoms remain. The vision in my right eye returned to 20/20, but it was never quite right.
Given the strong association of optic neuritis with MS, it makes sense to rule out MS. These days, that’s a fairly simple task. An MRI will show the swelling of the optic nerve. But more important is what’s going on in the brain itself. The radiologist will look for the classic white lesions that indicate demyelination of nerves in the brain. In the ONTT, the risk of developing MS in the following 10 years in those who had one or more lesions was 56 percent. It was only 22 percent if no lesions were present.
It’s important to know whether MS is a possibility. Treatment with intravenous steroids can speed recovery and delay the onset of MS. And experts now recommend starting treatment with one of the MS disease-modifying drugs with the onset of the first demyelinating event.
Did I mention that my baby is 21 years old? Forget the MS.
How did that happen?