There's no diagnostic test for post-polio syndrome. Diagnosis is based on a medical history and physical exam, and by excluding other conditions that could cause the signs and symptoms.
Indicators of post-polio syndrome
For a diagnosis of post-polio syndrome, doctors look for three indicators:
- Previous diagnosis of polio. This might require finding old medical records or getting information from older family members.
- Long interval after recovery. People who recover from the initial attack of polio often live for 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. The later-onset weakness typically occurs in muscles that were affected at the time of the initial polio illness. Weakness often isn't noticeable until it interferes with daily activities. You might 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 of other disorders, your doctor will attempt to exclude other possible causes, such as arthritis, fibromyalgia, chronic fatigue syndrome and scoliosis.
Tests to rule out other conditions
Because there are no tests that confirm a post-polio syndrome diagnosis, your doctor may use certain tests to rule out other conditions, including:
Electromyography (EMG) and nerve conduction studies. Electromyography measures the tiny electrical discharges produced in muscles. A thin-needle electrode is inserted into the muscles to be studied. 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 an abnormal condition of your nerves (neuropathy) and a muscle tissue disorder (myopathy).
- Imaging. Your doctor might recommend an MRI or CT scan to see images of your brain and spinal cord. These tests can help exclude spinal disorders, such as the degenerative spine condition spondylosis or narrowing of your spinal column that puts pressure on your nerves (spinal stenosis).
- Muscle biopsy. A muscle biopsy might be done to help your doctor look for evidence of another condition that could be causing the weakness.
- Blood tests. People with post-polio syndrome usually have normal blood test results. Abnormal blood test results could indicate another underlying problem that's causing your symptoms.
A noninvasive test shows promise for evaluating the severity of post-polio syndrome and monitoring its progression is muscle ultrasound, which uses sound waves to create images of muscles. More study is needed.