Modalities – SSEP

SSEP – Somatosensory Evoked Potentials

SSEP studies are averaged recordings of the body’s sensory response to electrical stimuli (small and painless) to determine the integrity of the somatosensory or special sensory pathways. SSEPs evaluate the entire somatosensory pathway through the peripheral nerves, to the spinal cord, the brainstem, and cerebral cortex upon stimulation of a peripheral axon.

In IOM, the method of eliciting responses is by repeated minute electrical stimulation of these peripheral axons (nerves), since this is easily controlled and tends to produce larger and better defined responses. Latency delays or amplitude reductions in these responses help define or locate any problem in the system of nerves and nerve pathways that transmit and process the responses.

SSEPs are most commonly used in spinal surgeries where the sensory pathways are at danger. SSEPs have become the recommended standard of care for corrective scoliosis surgery, are used frequently in cervical (neck) surgeries and are recommended in any lumbar surgery where the surgeon wishes to know any additional information about spinal integrity during the procedure.

SSEPs have always been thought of as the “gold standard” in spinal monitoring, but many studies now show the usefulness of combining SSEP studies with motor evoked potentials (TcMEPs) and electromyography (EMG) to provide the most protection for the patient’s neural structures. Until recently, the technology needed to combine modalities was unavailable, especially in certain areas of the country.