What Is Miller Fisher Syndrome?

Medically Reviewed by Christopher Melinosky, MD on March 07, 2024
Written by Sharlene Tan
4 min read

Miller Fisher syndrome is a very rare nerve disease that’s related to Guillain-Barré syndrome (GBS).

Guillain-Barré syndrome affects about one in 100,000 people. In the U.S., it’s estimated that 3,000 to 6,000 people develop Guillain-Barré syndrome each year.

Miller Fisher syndrome is a variant of Guillain-Barré syndrome. It’s rarer than Guillain-Barré syndrome. In Western countries, it makes up about 1% to 5% of all Guillain-Barré syndrome cases. The proportion is higher in some East Asian countries. Up to 19% of GBS cases in Taiwan and up to 25% of cases in Japan are Miller Fisher syndrome cases.

Both Miller Fisher syndrome and Guillain-Barré syndrome develop in response to an illness. The illness triggers antibodies to attack your nerves. Experts aren’t sure why this happens.

Miller Fisher syndrome usually develops a few days or up to 4 weeks after an illness, especially a diarrheal disease or respiratory infection.

Campylobacter jejuni is a common species of bacteria that triggers Miller Fisher syndrome and Guillain-Barré syndrome. These bacteria may cause diarrhea and abdominal pain. Viruses that trigger both diseases include:

People usually seek medical help because their vision decreases rapidly over days. They may also have difficulty walking.

The three main symptoms of Miller Fisher syndrome are:

  • Weakness of your eye muscles, which leads to double vision and difficulty controlling eye movements (ophthalmoplegia) 
  • Problems with limb coordination (ataxia)
  • Loss of reflexes in your tendons (areflexia)

Some people may also have:

  • dilated or enlarged pupils
  • weakness in their facial muscles
  • a decreased gag reflex

If you have these symptoms and also develop weakness in your breathing muscles and limbs, you may have GBS-MFS overlap syndrome. The main symptom of Guillain-Barré syndrome is weakness that begins in your legs and spreads to your arms and body. In some people, this weakness spreads to the face, throat, and breathing muscles.

It can be hard to diagnose this syndrome because it's similar to several other neurological diseases like:

There isn’t a specific diagnostic test for Miller Fisher syndrome. Your doctor will do a physical exam and take a medical history. They may do a spinal tap (lumbar puncture). Many people with Miller Fisher syndrome have a high protein count in their cerebrospinal fluid.

You may also need to do a blood test to check for anti-GQ1b antibodies. This antibody is found in about 95% of people with Miller Fisher syndrome.

Your doctor may also carry out a nerve conduction study and electromyography (EMG). These tests use small electric shocks to check the activity of your muscles and sensory nerves. If you have Miller Fisher syndrome, the tests may show abnormalities of your sensory nerves.

Magnetic resonance imaging (MRI) of your brain may be done to rule out brainstem encephalitis and Guillain-Barré syndrome. In Miller Fisher syndrome, an MRI is usually normal, but there may be abnormalities for the other diseases.

There’s no cure for Miller Fisher syndrome. But treatment can help your symptoms improve faster.

People with Miller Fisher syndrome are usually treated in the hospital. This will allow doctors to rule out Guillain-Barré syndrome, which can be fatal.

Because Miller Fisher syndrome is related to Guillain-Barré syndrome, treatments for Guillain-Barré syndrome are usually given. These treatments may include plasma exchange (plasmapheresis) and intravenous immunoglobulin (IVIg).

Intravenous immunoglobulin is usually the first treatment given because it's more widely available and convenient than plasmapheresis.

Intravenous immunoglobulin is usually given for 5 days. These infusions contain antibodies found in blood. They come from plasma that’s pooled from thousands of healthy people and then purified.

In plasmapheresis, a thin plastic tube connects your vein to a machine. Your blood travels through the tube and into the machine.

The machine removes the plasma in your blood and replaces it with substitute plasma. This substitute plasma and your own blood cells are then returned to your body.

For Miller Fisher syndrome, you’ll need about five rounds of plasmapheresis over about 2 weeks.

If your muscles are severely weakened by the disease, you may need physiotherapy for 1 to 2 weeks. The goal of rehabilitation is to strengthen your muscles and get function back to as close as normal as possible.

On average, recovery from this disease will take about 8 to 12 weeks. Most people fully recover within 6 months. Fewer than 3% have a recurrence.