Normal Evoked Potential Tracings

Back to Home Page

Pattern Visual Evoked Potential

Pattern Visual Evoked Potential

This waveform, looking like a "V", is found in the occiptal / parietal region of the brain. The main focus of attention when reading this is the so called P100 wave, sometimes called P1 or even P2 wave. The latency for this wave is about 100 ms, plus or minus about 9.5 ms.

Median Nerve Somatosensory E.P.

Somatosensory Evoked Potential
There are many montages for doing this test, and all have their advantages. There are several undisputed latencies, however. The first if ERBS point, recorded from ERBS point. The wave is also known as N9. As you will see, however, going strictly by latency has it's dangers in this type of testing. The next widely used point comes from the cervical spine. It is usually recorded from C5 or C7 (at least for the Median Nerve), and it's latency is about 13 ms. IT SHOULD ALSO BE NOTED THAT IN CERTAIN MONTAGES, there are other latencies which are vary close together, and they do not all originate from the same structures. The last commonly used latency is N19 and / or P22. These originate from the somatosensory cortex.

Brainstem Auditory E.P.

Brainstem Auditory Evoked Potential
The brainstem response consists of 5 waves which all people agree on. They are labeled waves I, II, III, IV, and V. The existence of waves VI, VII, and VIII is recognized, but they are mostly considered either not clinically useful and / or unreliable. The amplitudes of wave I and wave V are most always measured. This is done by measuring wave I' (pronounced "One prime") which is at the turn of the wave after peak I; and wave V' (pronounced "Five prime") which is at the next phase turn after peak wave V. Some also measure III'. The amplitudes of waves II and IV are usually not measured.

Click Here!