An EMG test checks how well your muscles and the nerves that control them are working. It’s usually done together with a nerve conduction study (NCS), which measures how quickly and how strongly signals travel along a nerve. Together, they can help find the cause of numbness, tingling, weakness or nerve pain.
When to get urgent care
Electrodiagnostic testing is planned care, not emergency care. Call 911 or go to the ER if you have:
- Sudden weakness or numbness on one side of the body, a drooping face or slurred speech
- Weakness that spreads quickly over hours or days, often starting in the legs, or any trouble breathing or swallowing
- Loss of bladder or bowel control, or saddle numbness in the groin, buttocks or inner thighs
- Sudden, severe weakness after an injury, such as a foot that drops or a hand that can’t grip
What an EMG test and nerve conduction study measure
Nerve conduction study
During the NCS test, small sticky electrodes are placed on your skin over a nerve and the muscle it supplies. Brief, mild electrical pulses travel along the nerve while a device records how fast and how strongly the signal moves. Slowed signals can point to a squeezed nerve, while weak signals can suggest damaged nerve fibers.
Needle electromyography
The physician places a very thin, sterile, single-use needle electrode into selected muscles. It records each muscle’s electrical activity at rest and as you tighten it. The pattern can show whether weakness comes from the muscle itself or from the nerve feeding it, and roughly where along the nerve a problem lies.
Why your doctor may order one
EMG and nerve conduction testing is often ordered when your symptoms or exam suggest a nerve or muscle problem, such as:
- Carpal tunnel syndrome, or pressure on the median nerve at the wrist
- A pinched nerve in the neck or low back, also called radiculopathy
- Peripheral neuropathy, such as nerve damage from diabetes
- Ulnar nerve entrapment at the elbow
- A nerve injury after trauma
- Unexplained muscle weakness, cramping or twitching
Results can confirm a diagnosis, show how severe it is and guide next steps. Electrodiagnostic testing is a core part of a physiatrist’s training; learn more about pain management and physiatry at PMR.
How to prepare for your EMG test
- Shower on the day of the test, and skip lotion, cream or oil on your arms and legs.
- Wear loose clothes that roll up easily.
- Keep your hands and feet warm, since cold limbs slow nerve signals.
- Eat normally and take your usual medicines unless you’re told otherwise.
- Tell us beforehand if you take blood thinners, have a bleeding disorder, have a pacemaker or implanted defibrillator, or have swelling (lymphedema) in an arm or leg.
What the test feels like and how long it takes
The nerve pulses feel like a quick snap or tingle, a bit like static electricity, and may make your muscle twitch. The EMG needle causes a brief pinch, and some muscles may ache while it’s in place. Most people find testing uncomfortable but manageable, and you can ask for a break at any time.
Testing often takes 30 to 90 minutes, depending on how many nerves and muscles need to be checked. Afterward, you may have mild soreness or small bruises for a day or two. Most people drive themselves home and return to their usual activities the same day.
Frequently asked questions
When will I get my results?
The physician interprets the findings and may go over the main points with you at the end of the test. A written report then goes to the provider who ordered the study. Your care team uses the results, along with your exam, to plan your treatment.
Is the test safe if I have a pacemaker or take blood thinners?
Usually, yes, with precautions. Nerve conduction studies are generally safe with a pacemaker, though the physician avoids stimulating near the device, and implanted defibrillators need extra planning. Most people on blood thinners can have needle EMG, but some deep muscles may be skipped. Tell us about either one before your visit.
What if my results are normal but I still have symptoms?
A normal result is still useful. It can rule out certain nerve and muscle problems and point your care team in a new direction. Some conditions, such as very early nerve compression or disorders of the smallest nerve fibers, may not show up on an EMG test. Your symptoms are still real, and your clinician will look at other explanations.
Schedule your EMG and nerve conduction test
Call the office nearest you to ask about testing, or request an appointment online. EMG is one of PMR’s diagnostic and treatment services.
- PMR of Danbury, CT: (203) 744-8013
- PMR of Brewster, NY: (845) 279-1135