EMG & Nerve Conduction Testing in Northern Virginia
Electrodiagnostic testing uses electromyography (EMG) and nerve conduction studies (NCS) to evaluate numbness, tingling, weakness, and other symptoms that may come from a nerve or muscle problem.
EMG & Nerve Conduction Testing at a Glance
Testing: Electromyography (EMG) and nerve conduction studies (NCS)
Purpose: Evaluate how nerves and muscles are functioning and help identify the source of certain neurologic symptoms
Common Symptoms Evaluated: Numbness, tingling, burning, weakness, radiating pain, muscle cramping, or unexplained changes in muscle function
Common Conditions Evaluated: Carpal tunnel syndrome, other nerve entrapments, cervical or lumbar radiculopathy, peripheral neuropathy, and selected muscle or nerve disorders
Test Length: Often approximately 30–60 minutes, depending on the areas and nerves that need to be evaluated
Medication Injected: None
Preparation: Avoid lotions, creams, or oils on the skin being tested and tell your physician about relevant medications, implanted devices, or bleeding conditions
What Is Electrodiagnostic Testing?
Electrodiagnostic testing evaluates how the nerves and muscles in your body are functioning.
It most commonly combines two related tests:
Nerve conduction studies (NCS) evaluate how electrical signals travel through selected peripheral nerves.
Electromyography (EMG) evaluates electrical activity within selected muscles and can help determine whether abnormalities originate from a muscle, a peripheral nerve, or a nerve root coming from the spine.
These studies are often performed together because numbness, tingling, weakness, and radiating pain can have several possible causes.
For example, numb fingers could result from carpal tunnel syndrome at the wrist, another compressed nerve farther up the arm, a nerve-root problem in the neck, or a more generalized peripheral neuropathy.
The purpose of electrodiagnostic testing is to provide additional information that helps distinguish among these possibilities.
What Is a Nerve Conduction Study?
A nerve conduction study measures how well electrical signals travel through selected nerves.
Small electrodes are placed on the skin over the nerve and nearby muscles.
A brief electrical stimulus is then applied to activate the nerve. Other electrodes record the nerve's response.
Your physician evaluates measurements such as how quickly the signal travels and how strong the response is.
Changes in these measurements can provide information about whether a nerve is damaged, where a problem may be located, and the type or severity of nerve dysfunction.
What Does a Nerve Conduction Study Feel Like?
Each electrical stimulus produces a brief sensation that patients often describe as a quick tingling, tapping, or shock-like feeling.
Several nerves may need to be tested depending on your symptoms.
The sensation lasts only briefly with each stimulation.
What Is an EMG?
Electromyography, commonly called a needle EMG, evaluates electrical activity within muscles.
During the test, a physician inserts a small, thin needle electrode into selected muscles.
The needle does not inject medication.
Electrical activity is evaluated while the muscle is relaxed and while you activate the muscle.
You may be asked to perform simple movements such as bending an arm, moving a foot, or gently contracting a particular muscle.
The pattern of electrical activity can help determine whether weakness or other symptoms may be related to a nerve problem, nerve-root injury, or muscle disorder.
What Does an EMG Feel Like?
The needle portion of an EMG can cause brief discomfort.
Some muscles may be more sensitive than others, and mild soreness or bruising can occasionally occur afterward.
Only the muscles needed to answer the diagnostic question are tested.
Why Might My Doctor Order an EMG or Nerve Conduction Study?
Electrodiagnostic testing may be recommended when symptoms suggest that a peripheral nerve, nerve root, or muscle may not be functioning normally.
Common reasons for testing include:
persistent numbness or tingling;
burning or electrical sensations;
pain that travels down an arm or leg;
unexplained muscle weakness;
hand or foot weakness;
muscle cramping or twitching;
symptoms suggesting a compressed nerve;
or difficulty determining whether symptoms originate from the spine or a nerve farther down the arm or leg.
Testing is individualized.
Not every patient with pain, numbness, or tingling needs an EMG or nerve conduction study.
Your physician determines whether electrodiagnostic testing is likely to provide useful information based on your symptoms, examination, medical history, and previous testing.
What Conditions Can EMG & Nerve Conduction Studies Help Evaluate?
Electrodiagnostic studies can help evaluate several common orthopedic and neurologic conditions.
Carpal Tunnel Syndrome
Carpal tunnel syndrome occurs when the median nerve becomes compressed as it passes through the wrist.
Symptoms commonly include numbness, tingling, burning, or discomfort involving the thumb, index, middle, and part of the ring finger.
Some patients also develop weakness or difficulty gripping objects.
Nerve conduction studies can help determine whether the median nerve is functioning abnormally across the wrist and can provide information about the severity of nerve involvement.
Testing can also help identify other possible sources of similar symptoms.
Learn more about hand numbness and carpal tunnel syndrome.
Cubital Tunnel & Other Nerve Entrapments
Peripheral nerves can become compressed or injured at several locations throughout the arms and legs.
Cubital tunnel syndrome involves compression of the ulnar nerve near the elbow and may cause numbness or tingling in the ring and little fingers.
Other nerve entrapments can affect nerves at the wrist, forearm, elbow, knee, ankle, or other locations.
Electrodiagnostic testing can help determine which nerve is involved and where abnormal nerve function may be occurring.
Learn more about hand, wrist and elbow conditions.
Cervical Radiculopathy
Cervical radiculopathy occurs when a nerve root in the neck becomes irritated or compressed.
Symptoms may include neck pain along with pain, numbness, tingling, or weakness extending into the shoulder, arm, or hand.
Electrodiagnostic testing may help distinguish cervical radiculopathy from conditions such as carpal tunnel syndrome, cubital tunnel syndrome, or another peripheral nerve problem.
Lumbar Radiculopathy & Sciatica
A nerve root in the lower spine can also become irritated or compressed.
Symptoms may include pain traveling from the lower back or buttock into the thigh, leg, or foot along with numbness, tingling, or weakness.
EMG and nerve conduction studies can sometimes help determine whether the symptoms are associated with nerve-root dysfunction and can help distinguish radiculopathy from peripheral neuropathy or another nerve condition.
Learn more about neck and back pain care.
Peripheral Neuropathy
Peripheral neuropathy occurs when nerves outside the brain and spinal cord become damaged or dysfunctional.
Symptoms can include numbness, tingling, burning, altered sensation, weakness, or balance problems, often beginning in the feet or hands.
Diabetes is one possible cause, but peripheral neuropathy has many potential causes.
Nerve conduction studies can provide information about which nerves are affected and the pattern of nerve involvement.
The underlying cause may require additional evaluation beyond an electrodiagnostic study.
Other Nerve & Muscle Disorders
Electrodiagnostic testing may also be used when a physician suspects other peripheral nerve, plexus, neuromuscular, or muscle disorders.
The specific nerves and muscles tested depend on the symptoms and the diagnostic question being investigated.
Can EMG Tell Where Numbness or Weakness Is Coming From?
Electrodiagnostic testing can often provide important information about the location and type of nerve or muscle dysfunction, but it is not a standalone answer for every symptom.
For example, testing may help distinguish:
carpal tunnel syndrome from a pinched nerve in the neck;
peripheral neuropathy from lumbar radiculopathy;
an individual nerve injury from a more widespread nerve disorder;
or nerve-related weakness from certain muscle disorders.
Your physician interprets the EMG and nerve conduction findings together with your medical history and physical examination.
Imaging, laboratory tests, or other diagnostic studies may sometimes still be necessary.
EMG vs. MRI: What's the Difference?
EMG and MRI answer different questions.
MRI Shows Anatomy
MRI creates detailed images of structures such as discs, nerves, muscles, ligaments, and other tissues.
It can show whether a disc is herniated, a spinal canal is narrowed, or another structural abnormality is present.
EMG & NCS Evaluate Function
Electrodiagnostic testing evaluates how nerves and muscles are actually functioning.
A person can have an abnormality on MRI that is not responsible for their symptoms.
Conversely, nerve dysfunction may sometimes be present even when imaging alone does not fully explain a patient's symptoms.
For certain problems, your physician may use both imaging and electrodiagnostic testing because the tests provide different types of information.
Can EMG Diagnose Carpal Tunnel Syndrome?
Electrodiagnostic testing can provide useful information when carpal tunnel syndrome is suspected.
Nerve conduction studies can evaluate the median nerve across the wrist and compare its function with other nerves in the same limb.
Testing may help:
confirm abnormal median-nerve function;
assess the severity of nerve involvement;
identify more widespread peripheral neuropathy;
or help distinguish carpal tunnel syndrome from cervical radiculopathy or another nerve problem.
However, electrodiagnostic testing is not automatically required for every patient with symptoms suggestive of carpal tunnel syndrome.
Your hand specialist determines whether testing is useful based on your symptoms, examination, and treatment plan.
How Should I Prepare for an EMG & Nerve Conduction Study?
Most patients need very little preparation.
Avoid Lotions, Creams & Oils
Do not apply lotion, cream, body oil, or similar products to the area being tested on the day of your appointment.
These products can interfere with the electrodes used during nerve conduction testing.
Clean, dry skin is best.
Wear Comfortable Clothing
Wear loose-fitting clothing that allows the physician to reach the arm, leg, neck, back, or other area being evaluated.
You may be asked to change into a gown depending on the location of testing.
Tell Us About Medications & Medical Devices
Before the study, tell the physician performing the test if you:
take blood-thinning or anticoagulant medication;
have a bleeding disorder;
have a pacemaker;
have another implanted electrical device;
or have another medical condition that may affect testing.
Do not stop prescribed medication unless your healthcare provider specifically tells you to do so.
What Happens During My EMG/NCS Appointment?
The exact study is customized to your symptoms.
Your physician first reviews the reason for testing and determines which nerves and muscles need to be evaluated.
Nerve Conduction Testing
Electrodes are placed on your skin and selected nerves are stimulated using brief electrical impulses.
Several nerves may be evaluated and compared depending on the diagnostic question.
Needle EMG
A thin needle electrode is inserted into selected muscles.
The physician evaluates electrical activity while the muscle is resting and during gentle contraction.
Not every muscle in an arm or leg needs to be tested.
The examination is designed to obtain enough information to answer the specific clinical question while limiting testing to what is medically necessary.
How Long Does Testing Take?
The length of the examination varies depending on your symptoms and how many nerves and muscles need to be studied.
Many electrodiagnostic examinations take approximately 30 to 60 minutes.
More complex studies may take longer.
What Happens After the Test?
In most cases, normal activities can be resumed after electrodiagnostic testing unless your physician gives you different instructions.
Some people experience temporary muscle soreness or minor bruising after the needle EMG portion.
The physician performing the study interprets the electrical findings and prepares the results.
Depending on how your care is arranged, findings may be discussed with you during the visit or sent to the healthcare provider who ordered the test.
The next step depends on the diagnosis.
Treatment could include observation, medication, therapy, splinting, an injection, surgical evaluation, additional testing, or another treatment based on the underlying condition.
Are EMG & Nerve Conduction Studies Safe?
Electrodiagnostic studies are generally well tolerated, but they are medical procedures and can cause temporary discomfort.
Nerve conduction testing uses brief electrical stimulation.
Needle EMG involves inserting a sterile, single-use needle electrode into selected muscles and can cause temporary soreness, minor bleeding, or bruising.
More significant complications are uncommon.
Providing an accurate medical history helps the physician perform the study appropriately and safely.
Who Should Perform an EMG?
Electrodiagnostic testing is more than simply collecting electrical measurements.
The physician performing and interpreting the examination must decide which nerves and muscles need to be studied, adjust the examination based on findings as the test progresses, and interpret those results in the context of the patient's symptoms and examination.
Appropriate training in electrodiagnostic medicine is therefore important for high-quality EMG and nerve conduction testing.
Electrodiagnostic Testing & Orthopedic Care
One advantage of electrodiagnostic testing in an orthopedic setting is that the results can help connect nerve symptoms with the appropriate next step in care.
For example:
A patient with carpal tunnel syndrome may need evaluation by a hand specialist.
A patient with symptoms originating from a nerve root in the neck or lower back may need nonsurgical spine care or rehabilitation.
A patient with peripheral neuropathy may require additional medical evaluation to determine the underlying cause.
The goal is not simply to identify an abnormal electrical signal. It is to use the findings to help guide appropriate care.
Learn more about Rehabilitation Medicine.
Frequently Asked Questions About EMG & Nerve Conduction Testing
Are EMG and nerve conduction studies the same test?
No. A nerve conduction study evaluates electrical signal transmission through peripheral nerves using electrodes placed on the skin. A needle EMG evaluates electrical activity within selected muscles using a small needle electrode. The tests are different but are often performed together because they provide complementary information.
Does an EMG hurt?
Some discomfort is possible. The needle used for EMG testing is thin, but insertion into a muscle may cause brief discomfort, and some patients experience temporary muscle soreness afterward. The level of discomfort varies from person to person and from one muscle to another.
Does a nerve conduction study hurt?
Nerve conduction testing uses brief electrical impulses that can feel like a quick shock, tingling sensation, or tapping feeling. The sensation ends immediately after each stimulation.
How long does an EMG test take?
Many EMG and nerve conduction examinations take approximately 30 to 60 minutes. The exact time varies because the physician selects the nerves and muscles that need to be tested based on your symptoms and findings.
Can I drive after an EMG?
Most patients can resume normal activities, including driving, after routine EMG and nerve conduction testing unless they receive different instructions from their physician.
Can EMG detect a pinched nerve?
EMG and nerve conduction testing can provide evidence of nerve-root dysfunction associated with conditions commonly described as a pinched nerve. The findings are interpreted together with your symptoms and examination and, when appropriate, imaging studies such as MRI.
Can EMG diagnose neuropathy?
Nerve conduction studies and EMG can help identify patterns consistent with certain peripheral neuropathies and provide information about the nerves affected. They do not necessarily determine why the neuropathy developed. Additional medical testing may be needed to identify the underlying cause.
Do I need a referral for EMG testing?
Referral requirements depend on your insurance plan and how the testing is being ordered. Some insurance plans may require a referral or authorization. Contact our office or your insurance carrier if you are unsure about your specific requirements.
Schedule an EMG & Nerve Conduction Study
If persistent numbness, tingling, weakness, radiating pain, or another symptom may be related to a nerve or muscle problem, electrodiagnostic testing can sometimes provide information that helps clarify the diagnosis and guide the next step in treatment.
