Tests and diagnosis

By Mayo Clinic Staff

Indicators of post-polio syndrome

To arrive at a diagnosis of post-polio syndrome, doctors look for three indicators:

  • Previous diagnosis of polio. This may require finding old medical records or getting information from older family members, because acute polio primarily occurs during childhood. The late effects of polio usually occur in people who were adolescents or older during the initial attack of polio and whose symptoms were severe.
  • Long interval after recovery. People who recover from the initial attack of polio often live for many years without further signs or symptoms. The onset of late effects varies widely, but typically begins at least 15 years after the initial diagnosis.
  • Gradual onset. Weakness often isn't noticeable until it interferes with daily activities. You may awaken refreshed, but feel exhausted by the early afternoon, tiring after activities that were once easy.

In addition, because the signs and symptoms of post-polio syndrome are similar to those commonly associated with other disorders, your doctor will attempt to exclude other possible causes, such as arthritis, fibromyalgia, chronic fatigue syndrome and scoliosis.

Some people with post-polio syndrome worry that they may be getting amyotrophic lateral sclerosis (ALS), also called Lou Gehrig's disease. But the late effects of polio are not a form of ALS.

Tests to rule out other conditions

Some of the tests your doctor may use to rule out alternative diagnoses include:

  • Electromyography (EMG) and nerve conduction studies. Electromyography measures the tiny electrical discharges produced in muscles. A thin-needle electrode is inserted into the muscles your doctor wants to study. An instrument records the electrical activity in your muscle at rest and as you contract the muscle. In a variation of EMG called nerve conduction studies, two electrodes are taped to your skin above a nerve to be studied. A small shock is passed through the nerve to measure the speed of nerve signals. These tests help identify and exclude conditions such as neuropathy, an abnormal condition of your nerves, and myopathy, a muscle tissue disorder.
  • Imaging. You may undergo tests, such as magnetic resonance imaging (MRI) or computerized tomography (CT), to produce images of your brain and spinal cord. These tests can help exclude spinal disorders, such as spondylosis, a degenerative spine condition, or spinal stenosis, a narrowing of your spinal column that puts pressure on your nerves.
  • Muscle biopsy. Your doctor may perform a muscle biopsy, looking for evidence of typical nerve abnormalities caused by the polio virus.
  • Blood tests. People with post-polio syndrome usually have normal blood test results. Abnormal blood test results may indicate another underlying problem that's causing your symptoms.
Mar. 03, 2011