Somatosensory Evoked Potential (SSEP) Testing

What is a Somatosensory Evoked Potential (SSEP)?

Somatosensory Evoked Potential (SSEP) tests are the most widely used evoked potential tests and are a great tool in electrodiagnosis. The stimulus in this testing method occurs in a particular extremity while the response is recorded on the top of the scalp. Responses are evaluated by neurologists to determine if the nerve pathways from the arms and legs to the brain are functioning properly.

What does a Somatosensory Evoked Potential (SSEP) diagnose?

Used to diagnose a number of different conditions, Somatosensory Evoked Potential (SSEP) tests evaluate the sensory pathways from nerve endings in the arms and legs to the brain by using electrical signals. From the responses recorded, your neurologist will be able to diagnose spinal cord injuries or diseases, neuromuscular and demyelinating diseases such as multiple sclerosis (MS). In patients that have suffered from spinal cord trauma or stroke, Somatosensory Evoked Potential (SSEP) testing has been helpful in establishing the degree of injury and determining a forecast of the likely course of progression. SSEP testing is even used for inoperative monitoring or patients undergoing neurosurgical procedures.

What to expect during your Somatosensory Evoked Potential (SSEP)

Somatosensory Evoked Potential (SSEP) testing relies on the patient being as relaxed and still as possible. Once you settle in either lying back in a reclining chair or lying down on an exam table, the technician will place tiny electrodes on various parts of your body such as your head, neck, lower back, arms, and legs. Depending on why the test is being conducted, you may have an upper SSEP involving the arms, a lower SSEP involving the legs, or possibly both at the same time. Traditionally, no matter if your test involves upper or lower extremities or both, the left and right sides of the body are tested together. After ensuring the electrodes have good connectivity, the testing will start with small electrical pulses to either the wrists or ankles, or both depending on the nerve being observed. The technician will increase the intensity of the pulses until a small motor twitch is produced. The sensation in the nerve endings can be mildly uncomfortable, but never painful. Somatosensory Evoked Potential (SSEP) testing has been well-studied and is widely used, meaning it is very safe and will have no long-term effects, and will not harm the body. During the testing, each nerve being examined will receive up to several thousand repetitions to ensure accurate readings are recorded. You should plan for each limb being tested to take anywhere from 10 to 20 minutes and if you are having all four tested at the same time the appointment may last up to three hours.

How to prepare for a Somatosensory Evoked Potential (SSEP)

When preparing for a Somatosensory Evoked Potential (SSEP) test you should wear comfortable, loose-fitting clothing. Clothes that allow easy access to the arms and legs are best, but you may still be asked to change into a gown before starting. Eating and drinking normally before and after the test is fine but be sure not to have any coffee or energy drinks at least four hours beforehand. The heightened nerves from the caffeine may interfere with the test readings. Because the technician will need to attach electrodes to the scalp, it is recommended to wash and dry hair thoroughly and avoid using sprays, gels, or oils. You should also continue taking medication regularly as prescribed, but also let the technician know what they are.

Have more questions? Feel free to contact your local Brain and Spine Specialists office to learn more about your upcoming Somatosensory Evoked Potential (SSEP).