Electromyography (EMG) involves doctors using needles to detect electrical activity in the muscles. This test can confirm a diagnosis of carpal tunnel syndrome.

Carpal tunnel syndrome occurs when the median nerve becomes compressed. The median nerve is found in a part of the wrist known as the carpal tunnel.

This article will discuss how doctors use EMG to diagnose carpal tunnel.

It describes how this test works, how to prepare for it, and what to expect during and after an EMG. It also details what happens after an EMG for carpal tunnel.

A person holding their wrist to help ease the pain of carpal tunnel syndrome -1.Share on Pinterest
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EMGs measure the electrical activity within a person’s muscles. EMGs help to diagnose carpal tunnel syndrome, as the condition can dysregulate electrical activity in the muscles of the hand and fingers.

A doctor will insert small needles into the muscles to perform an EMG. These needles are electrodes, which pick up electrical activity within the muscles.

Doctors attach the needles to an instrument — an oscilloscope — which shows the electrical activity in the form of waves.

There are several diagnostic uses for EMGs in relation to carpal tunnel syndrome:

  • Confirming a diagnosis: According to a 2022 article, EMGs can help confirm a positive carpal tunnel diagnosis when other tests have been insufficient.
  • Ruling out other conditions: A 2023 article explains that EMGs can rule out damage within the axons, which are parts of the nerves. This helps doctors to rule out other conditions.
  • Locating the area of damage: A 2018 review states that EMGs can also help doctors find the exact location of nerve pressure or damage. This helps doctors plan possible surgical interventions.

Doctors will discuss any steps people may need to take before an EMG, as these can vary from person to person. For instance, individuals with pacemakers or bleeding disorders may require special care during an EMG.

After cleaning the area of the skin with disinfecting wipes, a medical professional will insert the electrodes into the person’s muscles.

They will then ask the person to contract their muscles. Some contractions can be light, while others may need to be more forceful.

The oscilloscope will measure the muscles’ electrical activity during both kinds of contractions. They will also measure the muscles’ electrical activity during periods of rest.

An EMG test result may confirm a diagnosis of carpal tunnel syndrome or indicate the need for further testing. In some cases, it also indicates where the nerve pressure exists in the wrist.

Only doctors with special training can correctly interpret the results of an EMG.

When should a person expect their results?

How long a person has to wait for an EMG test result will vary from clinic to clinic. An individual’s doctor should inform them of how long they can expect to wait before receiving their results. They may even set a specific date.

If a person has not received news about their EMG results after an unexpectedly long time, they should contact their doctor.

If an EMG suggests that a person has carpal tunnel syndrome, the doctor will recommend treatment options.

Treatment can include:

EMG studies come with the following possible risks:

  • discomfort
  • pain
  • bleeding
  • infection

An individual can speak with a doctor about these risks. For people with severe bleeding disorders, doctors may not recommend an EMG.

The following are commonly asked questions about EMGs.

Is an EMG test painful?

A person may feel some discomfort as the doctor inserts the needle into the muscle. Some doctors try to avoid using EMG tests unless absolutely necessary because they can be painful.

Will an EMG show a pinched nerve?

EMG tests can help to diagnose a pinched nerve.

How long does an EMG test take?

There is no set amount of time for an EMG test. This is because doctors sometimes recommend other similar tests alongside an EMG.

Can a person have a negative EMG result and still have carpal tunnel?

According to a 2022 systematic review, EMG studies can yield false negatives. This means that someone can have a negative EMG result despite having carpal tunnel.

Carpal tunnel syndrome is when there is pressure on the median nerve of the wrist.

Since this can cause unusual patterns of electrical activity in muscles, doctors use EMG tests to help diagnose this condition. EMG tests use needle-thin electrodes to measure electrical activity in the hands and wrists

Treatment for carpal tunnel syndrome may involve wrist splinting, steroid injections, or surgery.