Numb, Tingly, Weak: How Nerve Pain Is Diagnosed

Chronic symptoms like numbness, tingling and weakness can be frightening under any circumstances. But without a cause, they can be even more unnerving. 

If you’re struggling with muscle or nerve pain, numbness, tingling or weakness, electromyography (EMG) and nerve conduction velocity (NCV) tests may provide answers. These tests evaluate function in the nerves and muscles, helping the specialists who administer them to diagnose and treat the cause of your symptoms. 

How Do Tests Work? 

EMG and NCV tests are tools used in electrodiagnostic medicine, or the study of muscle and nerve diseases. Unlike an X-ray or MRI, these tests don’t use pictures of body parts to gather information. Instead, they’re like an EKG -- they display images and sounds of electrical waves. 

Although both EMG and NCV tests are used to help identify the source of pain, numbness, tingling or weakness in the arms, hands, legs and feet, these tests work in different ways.

• EMG measures the muscles’ electrical activity using tiny needles inserted in specific muscles to evaluate the nerve-muscle communication.

• NCV measures how fast electrical impulses travel through the nerves using small electric shocks on the skin’s surface to evaluate the nerves’ response.

Diagnosing Nerve Pain 

If a doctor suspects a patient has nerve damage in the extremities, they might suggest an EMG and/or NCV test to help identify the cause. Both tests can be used to diagnose any problem that affects peripheral nerves, including: 

• Carpal tunnel syndrome 

• Pinched nerve at the elbow, shoulder, knee or ankle. 

•  Neuropathy caused by diabetes or other conditions 

• Pinched nerve in the neck or back due to a herniated disc or arthritis 

• Sciatica 

• Foot drop 

What To Expect 

The EMG and NCV tests are almost always done together. Since NCV testing involves small shocks, it can be mildly uncomfortable. But most patients can easily tolerate the discomfort. 

One study found that the level of pain patients reportedly expected to feel when undergoing an electromyography procedure was far higher than the pain they actually experienced. The tests are relatively brief, too. The whole process usually takes about 45 minutes. 

How Doctors Use EMG and NVC Results 

EMG and NCV test results can be key to unlocking the ideal treatment plan for a patient with nerve and muscle problems. Once nerve damage is identified and located, providers can determine the best course of action for addressing the problem. Some treatment and lifestyle adjustments your doctor might suggest: 

• Ergonomically designed desk or workstation

• Splint or brace

• Cortisone injections

• Nerve block or other epidural injections

• Physical therapy

• Home exercise program

• Surgery

• Medication for nerve pain 

These tests may help you avoid unnecessary and inconclusive tests and treatments, and may lead your doctor to order follow-up diagnostic work that can pinpoint the source of the problem, like bloodwork or an MRI. If the EMG or NCV tests find that there aren’t any nerve issues, doctors can look for other diagnoses like orthopedic or musculoskeletal causes of pain or weakness, which would require other treatments and imaging. 

Once you learn from the results of your EMG and NCV tests exactly what is happening, you and your doctor can deal with the problem effectively and efficiently.