What are response latency parameters for motor evoked potentials (MEPs)?

Updated: Aug 20, 2019
  • Author: Jasvinder Chawla, MD, MBA; Chief Editor: Selim R Benbadis, MD  more...
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Answer

Answer

Two techniques, the central method and the peripheral method, have been developed to subtract peripheral conduction time from the total scalp-to-muscle latency.

The central method uses a magnetic or electrical impulse over the cervical or lumbar spine. The stimulation point has been demonstrated to be at the intervertebral foramen, so the central conduction time includes the proximal root. For lumbosacral stimulation and the best response in the tibialis anterior, the inner edge should be moved to the L5 vertebral level. As the stimulation site for the nerve root is also at the intervertebral foramen, the central motor conduction time (CMCT) includes conduction through the cauda equina. The peripheral method uses F-wave latency.


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