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Somatosensory Evoked Potential (SSEP)

What is it?

Somatosensory Evoked Potential (SSEP) is a test that checks the electrical signals of sensation going from the body to the brain. The signals show whether the nerves that connect to your spinal cord are able to send and receive sensory information like pain, temperature, and touch. When ordering electrical tests to diagnose spine problems, your doctor may combine SSEP with an electromyogram (EMG), which is a test of how well the nerve roots leaving your spine are working.

Why is it done?

An SSEP indicates whether the spinal cord or nerves are being pinched. It is helpful in determining how much the nerve is being damaged and whether there is a bone spur, herniated disc, or other source of pressure on your spinal cord or nerve roots. An SSEP is used to double check whether the sensory part of the nerve is working correctly.

How is it done?

Either an electrode is placed on your skin or a needle is inserted into your nerve or the sensory center of your brain. Measurements of how long it takes an electrical signal to travel through the nerve pathway are recorded. The function of the nerve is determined by the speed of these electrical signals. When the nerve pathway is pinched, the signals are slower than expected.

What are the limitations?

An SSEP does not show why you have a problem or what is causing the problem. The test looks primarily at whether sensation is affected by a problem in your spinal cord or nerves. There could be a problem in the nerve somewhere between your brain and the area tested. The problem may not necessarily be in the spine itself.

What are the risks?

There are few risks associated with SSEP. There is a small chance of infection anytime a needle is inserted into your body. However, the risk is almost absent in this test.

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