Somatosensory Evoked Potentials (SSEP)
Somatosensory evoked potentials (SSEP) are used during spinal cord surgery, particularly spinal fusion procedures. SSEPs are performed by simulating a peripheral nerve at the wrist or the ankle and recording the responses from the popliteal fossa, cervical spine/brainstem, and somatosensory cortex. SSEPs give direct feedback from the posterior columns of the spinal cord. Any changes in the responses (a greater than 50 percent decrease in amplitude or a greater than 10 percent increase in latency) may indicate an interruption of the posterior column pathways. Dermatome sensory evoked potentials can also be useful in evaluating segmental nerve root function. This is accomplished by stimulating the cutaneous dermatome areas and measuring the response at the cortex.
Measuring the response at the posterior columns and cortex may not always be enough to indicate a problem however, since somatosensory evoked potentials may also be affected by high levels of anesthetic and decreased blood pressure. Therefore, our neural monitoring technologists have been trained to interpret the responses and identify the cause of changes in an effort to prevent negative post-operative outcomes.
Types of Surgeries that Use SSEP Monitoring
Somatosensory evoked potentials (SSEP) are used to monitor several surgical procedures, including:
- the sciatic nerve in acetabular fractures
- the lumbar and sacral nerve roots in posterior lateral interbody fusion, lumbar fusion with instrumentation, and cauda equine surgeries
- the spinal cord in spinal deformity surgery and spinal cord tumor surgeries
- the brainstem somatosensory pathways during instrumented cervical surgery
- the metabolic function of cortical structures during skull base surgery requiring retraction of the brainstem
- carotid endarterectomies
- aneurysm surgeries
Advantages of SSEP
Somatosensory evoked potentials (SSEP) continuously monitor the sensory neurologic pathways during surgery and have been very effective for monitoring the dorsal columns of the spinal cord. This decreases the risk for an obstructed blood vessel, accidental removal of the breathing tube, or a patient becoming conscious during the procedure.
Disadvantages of SSEP
Somatosensory evoked potentials (SSEP) are limited because while they are correlated with the overall spinal cord function, they do not indicate changes in the motor neurologic pathways. There have been a few cases in which the motor evoked potentials showed changes while the somatosensory evoked potentials remained unchanged. However, there is also evidence that the recordings may be disrupted by anesthetics or blood pressure. For this reason, SSEPs require trained personnel to properly interpret them.
If you are in need of somatosensory evoked potentials (SSEP) monitoring for your next surgical procedure, schedule an appointment with our neural monitoring technologists at Biotronic. We have a reputation for excellence and can protect your patients better than anyone else in the industry.