EMG – Electromyography Test – EMG Test – Neurological Services
Muscle and skeletal system is essential for the movement of limbs and all types of physical activity. The brain and nervous system play a very important role in the movement of hands and legs. The motor neurons or the nerve cells send signals to the skeletal muscles in order to control their movement. An Electromyography or EMG Test is performed to measure the health of muscles and the motor neurons. The electric signals that cause the muscles to contract are measured, recorded, and monitored on the EMG system.
What is an EMG test?
- This is an invasive test in which electrode needles are injected through the skin and into the muscle being studied.
- Electrodes do not pick up signals when there is no activity i.e. when the muscles are at rest.
- So, the technician asks the patient to contract the muscles which have electrodes in them.
- You may have to bend or stretch your arm or leg in a slow or fast manner, as directed by the technician.
- The electric signals of the muscles are picked up by the electrodes.
- These signals are then transmitted by wires to the oscilloscope or EMG monitor.
- The monitor displays the muscle and motor neuron signals as a wave form.
- The size and shape of the wave indicate the action potential.
- This information is interpreted by the doctor to measure the muscle ability and its response to stimulated nerves.
- The appearance and the sound of the electrical activity is recorded and displayed on the monitor.
- If an audio amplifier is connected to the EMG system, you can also hear the sound of muscle contraction.
What is a needle exam?
The EMG test for muscles is also known as a needle exam. It is different from a similar procedure known as the Nerve Conduction Velocity or NCV.
What is NCV?
NCV test is used to stimulate the nerves at different points by giving small electric shocks. The artificial stimulation is necessary for measuring the speed with which the electric impulse travels in the nerve. Sometimes, the neurologist may suggest both NCV and EMG test together.
What are the uses of EMG test?
- The test is very efficient in measuring muscle and nerve activity.
- Weakness in the needled muscles can be detected in an effective manner.
- EMG also diagnoses disorders of the nerves that have been stimulated during the exam.
- Muscle weakness from pain or lack of motivation can be differentiated from true weakness using this test.
Will there be any pain during the test?
Since the test is invasive, the needle injection can cause a sharp pain for short time. The muscles will also tingle and there will be some soreness around the injected area. Very rarely, the patient may have swelling, puss, or tenderness in the muscle. In such cases, the patient should consult the doctor or call the centre for more guidance.
How long does the test take to finish?
The test for one leg or hand can take about 15 to 20 minutes to complete. Additional testing like NCV may take around 30 more minutes to finish.
- Consult the neurologist for complete details of the EMG and sign the consent form after clearing all your queries.
- Inform the doctor about implants such as pacemakers, prescription drugs for current diseases, and herbal and vitamin drinks or pills that you take.
- Fasting is not necessary, but avoid soft drinks, tea, smoking, coffee and other caffeinated drinks for at least 2 to 3 hours before the test.
- Do not apply or rub cosmetics such as lotions or oils on your body for a few days before the test.
- Keep your hand and leg muscles supple and free from injury before the test.
- After the test is completed, you can leave immediately as sedatives or anesthetics or painkillers are not injected.
- If you have pain or swelling in the injected area, inform the doctor before you leave or call the centre for more help.