EMG (or Electromyography) during Sleep Study

EMG allows experts to monitor and check muscle and nerve function in the body; it is a very similar test to EEG, which studies brain waves. EMG testing during a sleep study, or polysomnography, will help sleep experts diagnose and treat such diseases as restless leg syndrome and periodic limb movement disorder. A very small needle will need to be placed into a muscle before the test can work. The needle picks up electricity emitted from the muscles, either when muscles contract or when nerves inside the muscles “feel” a sensation. Recordings may come in the visual form, producing wavy lines on a chart, or audible form, translating electrical impulses made in the body to certain sounds that can be heard by the doctor using headphones or speakers. Since muscle activity is typically pretty low while a person is resting, excessive muscle and nerve activity detected during a sleep study may indicate the presence of a sleep disorder.

The insertion of the needle into a person’s muscles may cause soreness during the days after an EMG test. Unlike EEG testing, EMG requires access inside the body and is therefore more invasive than EEG and may make patients more wary because of the possibility of bleeding or infection where the needle touches the skin. However, the EMG procedure is, overall, a very safe and low-risk medical procedure, and patients should rest easy knowing that the test is widely accepted by the medical community. Receiving a proper diagnosis of why a muscle in the body may not be working correctly, or being able to identify whether a muscle problem is caused by external injury to internal nerve damage will be well worth any risk the procedure might introduce and will allow doctors to treat any sleep disorder conditions in the best way possible.

Preparing for an EMG Test

Similar to how the head and hair should be thoroughly cleaned before an EEG test, a person’s body (sometimes just at the location being tested) should also be cleaned before the needle is placed. Lotions and sprays, especially scented ones, may cause complications, so it’s best to avoid those on the day of the EMG test. Depending on the weather outside, the performing doctor may also need to adjust temperature inside the examination room, as body temperature may trigger abnormal muscle function and may mess up the results of the test. Talk to a sleep specialist if you have concerns about EMG testing during your sleep study.