ELECTRODIAGNOSTIC STUDIES (EMG/NCS)
The physicians at Lake Washington Sports & Spine perform electrodiagnostic studies, which usually consist of two parts:
- Nerve Conduction Studies
- Electromyography (EMG)
Please do not apply any lotion or perfumes the day of your procedure
Nerve conduction studies
Small pulses of electricity are conducted along your limb to see how well the nerves conduct electricity.
Small pulses of electricity are conducted along your limb to see how well the nerves conduct electricity.
- The setup for this study involves attaching small electrodes to your skin, labeled G1, G2, and GND in the picture below
- Using a probe (labeled CATH below), we stimulate with electricity. This pulse of electricity feels similar to the shock ones gets from static electricity when touching a doorknob after walking across carpet.
- We measure this pulse of electricity to see if the nerves are sending an appropriate signal.
- The number of stimulations varies per patient, but we typically will assess 2-5 nerve studies per limb tested, with 4-10 stimulations per nerve
Electromyography
A small needle (about the size of a pin) is inserted into muscles and delicately moved to assess different portions of each muscle for electrical activity.
Following the procedure, you may have some muscle soreness and light bruising. We recommend applying ice for 20 minutes if this soreness is bothersome.
A small needle (about the size of a pin) is inserted into muscles and delicately moved to assess different portions of each muscle for electrical activity.
- The pattern of muscle contraction is recorded using sound and a visual monitor.
- The number of muscles per limb may vary per study, but we typically sample between 3-7 muscles for each limb under investigation. Our goal is to test the fewest muscles needed to be diagnostically accurate.
- This test has a very high positive predictive value, and is therefore very meaningful if it finds something
- The test is less meaningful if it comes back as normal, but is still diagnostically useful
- EMG is a useful adjunct to history, physical examination, and imaging studies
Following the procedure, you may have some muscle soreness and light bruising. We recommend applying ice for 20 minutes if this soreness is bothersome.
