Electromyography (EMG)

What is Electromyography?

Electromyography (EMG) is a diagnostic test used to assess the health of muscles, and the nerve cells that control them. These nerve cells, known as motor neurons, transmit electrical signals that enable muscle movement. An EMG measures the electrical activity in muscles, providing crucial insights into neuromuscular function.

By detecting abnormalities in muscle response, and nerve conduction, EMG plays a vital role in diagnosing conditions that affect the nervous system, muscles or the connection between them. In fact, Neurologists frequently use EMG to evaluate unexplained muscle weakness, numbness, tingling, and other neurological symptoms.

When is Electromyography recommended?

A neurologist may recommend an EMG if you experience symptoms that suggest nerve or muscle dysfunction. These include:

• Difficulty with movement or coordination.
• Muscle weakness, cramps, or twitching (fasciculations).
• Suspected nerve compression or damage, such as from carpal tunnel syndrome or a pinched nerve.
• Tingling or numbness in the limbs.
• Unexplained pain or muscle atrophy (wasting).
• Evaluation of conditions like neuropathy, myopathy or motor neuron disorders.

How does Electromyography work?

EMG involves placing small, thin needles, known as electrodes, into the muscles to measure their electrical activity. The procedure is performed in two main parts, which are:

• Nerve Conduction Study (NCS) – electrodes are placed on the skin to measure how well electrical signals travel along the nerves. This assesses nerve function, and detects potential nerve damage.

• Needle EMG – a fine needle electrode is inserted into specific muscles to evaluate their electrical activity both at rest, and during movement. The recorded signals help identify abnormal muscle or nerve function.

What are the benefits of Electromyography?

EMG is a crucial tool for diagnosing, and managing neurological, and muscular conditions. Its key benefits include:

• Accurate diagnosis – EMG detects nerve, and muscle abnormalities that other tests might miss.
• Customised treatment planning – the results help neurologists develop targeted treatment plans.
• Early detection – it identifies neuromuscular conditions in their early stages, allowing timely intervention.
• Minimally invasive – the test is safe and does not involve radiation or complex procedures.
• Precise localisation – EMG pinpoints the exact location of nerve damage or muscle dysfunction.

Which conditions are Electromyography used to diagnose?

An EMG helps diagnose a variety of neuromuscular disorders, including:

• Carpal tunnel syndrome – compression of the median nerve in the wrist, leading to numbness and weakness.
• Guillain-Barre syndrome – an autoimmune condition causing sudden nerve damage, and muscle weakness.
• Motor neuron diseases (MND) – conditions like amyotrophic lateral sclerosis (ALS) that affect nerve function.
• Muscle disorders – myopathies, muscular dystrophy, and polymyositis.
• Myasthenia gravis – a disorder affecting nerve-muscle communication.
• Peripheral neuropathy – nerve damage caused by diabetes, infections, or injuries.
• Radiculopathy – nerve root compression or irritation, often due to herniated discs or spinal issues.

What results can I expect?

After your EMG test, a neurologist will analyse the recorded electrical activity in your muscles, and nerves. The results will indicate whether your symptoms are caused by a nerve disorder, a muscle condition or another underlying issue.

RESULTS	DEFINITION
Negative (Normal)	A normal EMG result means your muscles, and nerves are functioning properly without any signs of damage or dysfunction. If your symptoms persist despite normal results, our neurologist may recommend additional tests, such as MRI scans, blood tests or nerve function assessments, to explore other potential causes. In some cases, symptoms may be due to temporary factors like stress, electrolyte imbalances or mild inflammation, which can resolve on their own.
Positive (Abnormal)	A positive EMG result indicates irregular nerve or muscle activity, suggesting an underlying neuromuscular condition. Depending on the type of abnormality detected, our neurologist will classify the findings into specific categories, such as: Nerve-related disorders (neuropathies) – possible causes include carpal tunnel syndrome, peripheral neuropathy or a pinched nerve (radiculopathy).Muscle disorders (myopathies) – conditions like muscular dystrophy or polymyositis may be diagnosed.Motor neuron diseases – if nerve signals are severely impaired, conditions like amyotrophic lateral sclerosis (ALS) may be considered. Based on these findings, our neurologist will discuss the next steps, which may involve further testing, referral to a specialist or the initiation of a treatment plan tailored to your condition.
Abnormal but Inconclusive	Sometimes, an EMG may show some irregularities that do not point directly to a specific diagnosis. In such cases, additional tests — such as nerve conduction studies (NCS), MRI scans or blood work — may be needed for a clearer picture. Our neurologist may also recommend lifestyle changes, physiotherapy or symptom management strategies while monitoring your condition over time.

How many sessions are needed?

Most patients require just one EMG session, lasting between 30 and 90 minutes, depending on the areas being tested. However, follow-up sessions may be necessary in certain cases, such as monitoring disease progression or assessing treatment effectiveness. 

The need for additional tests will be determined by our neurologist based on your symptoms, initial results, and overall condition.

Book An Appointment

EMG is a powerful diagnostic tool that helps detect neuromuscular disorders with precision. By identifying nerve, and muscle dysfunction early, EMG enables timely intervention, and personalised treatment plans.

If you are experiencing unexplained muscle weakness, tingling or nerve-related symptoms, schedule an EMG appointment at Siow Neurology today. Remember, early diagnosis can make a significant difference in managing neurological conditions effectively.

Frequently Asked Questions

Is electromyography painful?
Electromyography involves inserting thin needles into muscles to measure electrical activity, which may cause mild to moderate discomfort. Most patients describe the sensation as a quick pinprick followed by a slight aching or twitching when the muscle is activated. The level of discomfort varies depending on the muscle being tested, and individual pain tolerance.

If NCS is performed alongside EMG, small electrical impulses will be delivered to the skin to assess nerve function. This may create a tingling or mild shock-like sensation but is generally well tolerated.

The discomfort typically subsides shortly after the test, though some people may experience minor soreness or bruising at the needle insertion sites. If needed, over-the-counter pain relief ,and gentle stretching can help ease post-test discomfort.

How should I prepare for electromyography?
Proper preparation ensures accurate results, and a smooth testing experience. Here are some key steps to follow:

• Avoid applying lotions, creams or oils on the day of the test, as they can interfere with electrode placement.

• Eat a light meal beforehand, as fasting is not required. However, avoid excessive caffeine intake, as it may affect muscle activity readings.

• Ensure your skin is clean and dry, as sweat or dirt can affect the accuracy of the nerve conduction study.

• Inform our neurologist if you are on blood-thinning medications, have a pacemaker or have any underlying medical conditions that might affect the test.

• Wear loose, comfortable clothing to allow easy access to the areas being tested. In some cases, you may be asked to change into a hospital gown.

Are there any risks associated with electromyography?
EMG is a safe and well-established procedure with minimal risks. However, some temporary side effects may occur, including:

• Mild soreness or bruising at the needle insertion sites, which usually resolves within a few days.
• Rare bleeding or swelling, particularly in patients on blood thinners.
• Slight risk of infection, though this is extremely rare due to the use of sterile needles.
• Temporary numbness or tingling in the tested areas, which typically fades quickly.

Is electromyography better than an MRI?
EMG, and Magnetic Resonance Imaging (MRI) serve different diagnostic purposes:

• EMG assesses nerve, and muscle function by measuring electrical activity, making it ideal for detecting conditions like neuropathy, muscle disorders, and nerve compression.
• MRI provides detailed anatomical images of soft tissues, nerves, and bones, making it useful for identifying structural abnormalities, such as herniated discs, tumours, or multiple sclerosis.

Can I drive home after an electromyography?
Yes, most patients can drive home after an EMG. The test does not require sedation or anaesthesia, so cognitive, and motor functions remain unaffected. However, consider having someone to accompany you if:

• You are anxious about the test, and feel lightheaded or fatigued afterwards.
• You have had extensive testing on multiple muscle groups, leading to temporary soreness.
• You experience muscle weakness or numbness that affects your ability to operate a vehicle safely.

How long does it take to get results?
The duration for receiving results depends on your healthcare provider, and the complexity of your case. Typically:

If urgent findings are detected, our neurologist may expedite the results, and discuss them with you sooner.

A preliminary assessment may be available immediately after the test.

A full, detailed report is usually ready within a few days to a week, as the neurologist carefully analyses the data.