What is it?

Somatosensory evoked potential (SEP) studies are neurophysiological tests used to explore the entire sensory pathway, from the peripheral nerves to the cerebral cortex. They provide valuable information on the efficiency of sensory signal transmission throughout its journey in the nervous system.

How is the procedure performed?

In practice, the test is very similar to an electromyogram. As with an EMG, it relies on low-intensity electrical stimulations applied to a peripheral nerve, most commonly at the wrist or ankle.

This stimulation triggers an activation that travels from the periphery to the cerebral cortex, where sensory information is processed. Electrodes are placed at several strategic checkpoints along this neural pathway to record the signal at each level.

However, what distinguishes SEPs from an EMG is the analysis: the anatomical regions explored and the interpretation of the results are entirely different.

Areas explored during the test

The electrodes record the nerve signal at the following key points:

• Peripheral nerve / brachial plexus

• Lumbar or cervical nerve root

• Spinal cord

• Brainstem

• Cerebral cortex

At each of these levels, the response time and the amplitude of the recorded potential are measured. An absent or delayed potential at a specific level suggests a localized abnormality at that precise point. This makes the test exceptionally useful for locating sensory impairment.

Both the upper and lower limbs can be explored, depending on the clinical indication.

When is this test prescribed?

SEPs are indicated for the diagnosis and assessment of several conditions:

• Multiple sclerosis

• Demyelinating peripheral neuropathies

• Spinal cord compression

• Unexplained sensory disturbances

• Myelitis (inflammation of the spinal cord)

  
  

Practical details

This is a medical procedure performed strictly on prescription. It can be combined with an electromyogram or a motor evoked potential study, depending on the requirements of the neurological assessment.

At a glance

• SEPs explore the sensory pathways from the periphery to the brain

• The procedure relies on low-intensity electrical stimulations

• It allows for the precise localization of abnormalities along the sensory pathway

• It is valuable in assessing multiple sclerosis, spinal cord compressions, and unexplained sensory disturbances

• A medical test, available on prescription only, which may be combined with an EMG or motor evoked potentials

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Book an appointment for an SEP study at Paris IENA Neurophysiologie

By telephone on 01.89.74.47.69 or via Doctolib

Find out more about the diagnostic tests performed at IENA Neurophysiologie