How is a SSEP test performed?
A small electrical current is sent through a probe to the skin near a nerve on your wrist or ankle. This may be done several times. This makes a twitching or pulsating feeling in your wrist and ankle. Your thumb or big toe may twitch during the test.
What is an SSEP test?
SSEP (Somatosensory Evoked Potential) is one of the many intraoperative neurophysiological monitoring tests that is used during a surgery. The SSEP test monitors the nerve pathways that are responsible for feeling pressure, touch, temperature and pain.
What is SSEP and MEP monitoring?
Anesthesia for Pediatric Neurosurgery
MEPs are a top-down monitoring method of measuring brainstem and spinal cord integrity, whereas SSEPs are a bottom-up system.
Which nerve is commonly used for upper SSEP stimulation?
Most of the clinically used SSEPs are elicited by electrical stimulation to the peripheral nerve, although more natural stimuli such as pain or touch sensation can yield SSEPs. The commonly used sites of stimulation are the median nerve at the wrist and posterior tibial nerve at the ankle.
What are limitations of SSEP?
Further limitations of SSEPs are the monitoring of patients with pre-existing neurologic deficit (myelopathy, spinal cord tumour, peripheral neuropathy), or situations with the intraoperative isolated motor pathway or nerve root injury, which can be detected only by MEP or EMG type of recording.
How long does an SSEP test take?
We usually allow up to 90 minutes for the whole test to be completed. Are there any risks? No, the SSEP test is very safe. The procedure may be slightly uncomfortable but is usually painless.
What does an abnormal SSEP mean?
A significant change in the somatosensory evoked potential (SSEP) responses is indicated by a decrease in amplitude and/or an increase in latency. The abnormalities detected by SSEP do not provide a specific diagnosis but point to impaired function in that particular sensory pathway [11].
How do you do SSEP?
How SSEP Works
- Electrodes are attached to the skin over the scalp or spine.
- A second set of electrodes are placed on the skin over the wrist, the back of the knee, or another location.
- A mild electrical current is transmitted to the electrodes on the wrist, knee or other peripheral area.
What are the 3 types of SSEP interleaving combinations used?
3. What are the 3 types of SSEP interleaving combinations used? (A) Interleaving upper limbs and then lower limbs; interleaving the left and then the right side of body; four-limb (all nerves) interleaving.
Why do we measure evoked potential?
Evoked potentials are used to measure the electrical activity in certain areas of the brain and spinal cord. Electrical activity is produced by stimulation of specific sensory nerve pathways. These tests are used in combination with other diagnostic tests to assist in the diagnosis of neurological disorders.
What is short latency somatosensory evoked potential study?
Somatosensory evoked potentials (SSEP) are a measure of the short latency (20ms) cortical response at the postcentral gyrus to a peripherally applied electrical stimulus to a nerve in the forearm. From: Handbook of Clinical Neurology, 2021.
What is normal P100 latency?
In our study, the mean latency (in milliseconds) of P100 wave in normal female subjects was 88.31 ± 8.799 and 88.788 ± 8.984 in the left and right eye respectively. The mean latency (in milliseconds) of P100 wave in normal male subjects was 93.214 ± 10.656 and 93.41 ± 10.628 in the left and right eye respectively.
What are the types of evoked potential?
There are three kinds of evoked potentials in widespread clinical use: auditory evoked potentials, usually recorded from the scalp but originating at brainstem level; visual evoked potentials, and somatosensory evoked potentials, which are elicited by electrical stimulation of peripheral nerve.
What is normal VEP?
Visual evoked potentials (VEP) are used to assess the visual pathways through the optic nerves and brain. A normal VEP response to a pattern-reversal stimulus is a positive mid occipital peak that occurs at a mean latency of 100 ms.
What does P100 of a VEP represent?
The number following the letter is the time in milliseconds of the average occurrence of the peak (eg, P100 is a positive peak normally occurring around 100 milliseconds). P100 is a commonly examined feature of the conventional waveform. Latency and amplitude are other important characteristics of the VEP.