MEPs/motor evoked potentials
are a supportive diagnostic method used to assess possible impairment of the motor pathway, for example in patients with central motor disorders such as multiple sclerosis, neurodegenerative diseases, or spinal cord compression caused by a herniated intervertebral disc.
The examination is performed by a neurologist together with a nurse. A magnetic coil is placed on the head, cervical spine, and lumbar spine to deliver stimulation. The responses are recorded using surface electrodes applied to the skin over specific muscles of the upper or lower limbs.
Contraindications: patients with a pacemaker and pregnant patients.
The results are evaluated by the neurologist.
In certain cases, such as prior to a planned neurosurgical or spondylosurgical consultation, or directly before surgeries of the cervical or lumbar spine, the Motor Evoked Potentials (MEP) examination is supplemented by an Electromyography (EMG) examination.
If the MEP examination is part of your spine surgery preparation, we highly recommend utilizing our comprehensive pre-operative packages within the Vertebrogenic Center.
FAQ
1. How does the MEP examination work and what will I feel?
The examination maps the conductivity of the motor pathways from the brain down to the muscles in your arms or legs. It is performed using a special stimulation coil placed against your head (above the motor cortex) and spine.
- The coil emits short magnetic pulses that painlessly penetrate the skull to stimulate nerve cells.
- At the moment of the pulse, you will feel a quick, painless twitch in the muscles of your arms or legs (depending on which pathway is being tested).
- The only accompanying effect of the stimulation is a louder clicking sound from the device.
2. Does the MEP examination hurt?
There is no need to worry; the examination is not painful. Most patients describe the sensation during head stimulation as unusual or surprising (you perceive a mechanical tapping on the scalp followed by a muscle twitch), but definitely not painful. The entire procedure is conducted in a calm environment with maximum regard for your comfort.
3. How long does the examination take?
The measurement of motor evoked potentials itself is very fast. Including brief preparation (attaching recording electrodes to the arms or legs) and subsequent evaluation, the entire visit takes approximately 20 to 30 minutes.
4. How should I prepare for the MEP examination?
The examination requires no special preparation. You can eat, drink, and take your prescribed medications normally.
- Important: On the day of the exam, please wash your hair and do not apply any hair gel, hairspray, or other styling products to your hair, and do not moisturize your body skin (arms, legs) with creams. Your hair should be clean and dry so that stimulation and recording function properly.
- Before the test, we will ask you to remove all metal objects from the vicinity of your head and neck (earrings, necklaces, hair clips, glasses).
5. When is the MEP examination contraindicated?
Because we utilize a strong magnetic field during the exam, there are strict limitations. The MEP examination cannot be performed if you have:
- An implanted pacemaker, defibrillator (ICD), or cochlear implant.
- A metal implant in your head or cervical spine area (e.g., clips after aneurysm surgery, metal plates, etc.—standard dental implants or amalgam fillings are perfectly fine).
- Diagnosed epilepsy or if you are recovering from a recent neurosurgical procedure.
- Pregnancy (in this case, we perform the examination only after strict consideration by the physician).