Nerve Mapping

What is Nerve Mapping?

Nerve Mapping is a method of precisely locating nerves and measuring their function in real-time during surgery. This allows the surgeon to reduce the risk of nerve injury and assess nerve health intra-operatively.

Nerves control the muscles in the body by sending electrical signals called impulses. These impulses make the muscles react in specific ways. These impulses can be used to assess and map nerves, and nerve health.

Why Use Nerve Mapping?

The NeuroSurgery Spine Center uses a new, cutting edge technology called Mechanomyography, or MMG, to map the nerves and nerve structures during surgery. This technology helps the surgeon locate and avoid nerves and nerve roots with great accuracy, helping manage risk during the surgical procedure.

How does MMG work?

MMG smart-sensors are adhered to the surface of the patient’s skin directly overtop the muscles. There are neither invasive needles nor special skin preparation for the placement of the smart-sensors. During surgery, the surgeon uses a small tool to stimulate the nerves.When a nerve is located, the surgeon is provided with a ‘STOP’ alert.When no nerve response is present, the surgeon receives a “GO” indication.

MMG Nerve Mapping System
SentioMMG® Nerve Mapping System

Pre-operative Electromyogram

Nerve Conduction Studies

Nerve conduction studies are performed to:

Assess disorders of the peripheral nervous system which includes the nerves that lead away from the brain and spinal cord and the smaller nerves that branch off from those nerves. Nerve conduction studies are often used to help diagnose nerve disorders such as pinched nerves, carpal tunnel syndrome or Guillain-Barre syndrome.

Both EMG and nerve conduction studies can help diagnose a condition called post-polio syndrome that may develop months to years after a person has had polio.

How to Prepare?

Inform your doctor regarding the following:

  • Medications: Certain medicines that act on the nervous system can change electromyogram (EMG) results. You may need to stop taking these medicines 3 to 6 days before the test.
  • Bleeding: If you have a history of bleeding problems or take blood thinners, such as coumadin, heparin, or aspirin, your doctor will tell you when to stop taking them before the test.
  • Pacemaker: Let your doctor know if you have a pacemaker. Generally, this is not a problem, but nerve conduction stimulation will be avoided near the pacemaker.
  • Smoking: Do not smoke for 3 hours before the test.
  • Lotions: Do not apply lotion to the arms or legs on the day of the test.

How is the Procedure Performed?

Electromyogram: During the electromyography test, the physician cleans the skin with alcohol and inserts a tiny needle with an electrode into the muscle. The electrical activity of the muscle is recorded and viewed on a screen called an oscilloscope. The physician analyzes the activity on the screen and listens to the sounds of the activity through a speaker. This helps the physician determine if there are abnormalities in the muscle or the nerve going to the muscle.

Electromyogram: An EMG may take 30 to 60 minutes. When the testing is complete, the electrodes are removed and the injection sites are cleaned with alcohol.

Nerve conduction studies: In this test, several flat metal disc electrodes are attached to your skin with tape or a special paste. A shock-emitting electrode is placed directly over the nerve and a recording electrode is placed over the muscles under control of that nerve. Several quick electrical pulses are sent to the nerve. The time it takes for the muscle to contract in response to the electrical pulse is then recorded.

Nerve conduction studies: The speed of muscle contraction response is called the conduction velocity.

Nerve conduction studies are done before an EMG if both tests are being performed. Nerve conduction tests may take from 15 minutes to 1 hour or more, depending on how many nerves and muscles are studied.

What are the Risks?

An electromyogram (EMG) is very safe. You may have some pain in the muscles after the procedure or small bruises or swelling at the needle injection sites. Sterile technique is used so there is very little chance of developing an infection at the injection sites.

There are no risks associated with nerve conduction studies. Since it is a non-invasive procedure, there is no chance of infection. The voltage associated with the electrical pulses is not high enough to cause an injury.

Although every effort is made to educate you on ELECTROMYOGRAM and take control, there will be specific information that will not be discussed. Talk to your doctor or health care provider about any concerns you have about ELECTROMYOGRAM.