What is EMG?
EMG, electromyography, is a special method used to diagnose nerve and muscle dysfunctions with a special device. The history of EMG test dates back to almost 100 years ago. In parallel with the developments in modern medicine, we have seen many new tests accumulated on the simple nerve and muscle measurements for the last 20-30 years. With the advancements of automatic devices, we are now able to run assays very quickly.
How To Perform EMG
EMG is composed of two main evaluations. Nerve conduction studies and needle EMG. These also include various tests. The physician performing EMG determines the tests. Needle EMG is not performed for every patient. Nerve conduction study is conducted with electrical impulses of short and low voltage. It basically covers all the procedures to measure electric conduction rate of the nerves. This way, the physician can test the function of motor and sensory nerves. For needle EMG, a needle electrode inserted directly into a muscle evaluates the muscle fibers and provides information on both the muscle and the relevant nerves.
How To Perform EMG ? Watch The Video
Who Can Perform EMG?
Only trained physiatrist or neurologists can perform EMG. EMG device can allow for many tests. Thus, in order to perform the majority of these tests a specialist must be trained for at least 2-3 years after BA. In some hospitals, technicians perform some of the EMG tests. Since it is a very dynamic test, it is highly undesirable for a technician to perform EMG without the supervision of a specialist.
Who Orders EMG?
Physical therapists, neurologists and neurosurgeons usually order EMG. Although not so often, other specialsts may also order EMG test.
How Does EMG Help Diagnosis?
EMG can provide direct diagnosis in many nerve and muscle diseases. In some cases, it is used to support or validate the diagnosis.
For The Diagnosis of Which Diseases is EMG Ordered?
EMG is ordered to help in the diagnosis of lumar and cervical disc herniations, muscle diseases (myopathy, muscular dystrophy), nerve diseases, nerve compressions, injury to nerves, sciatic nerve injury, neuromuscular transmission disorders, spinal cord disorders, facial palsy and some other nerve paralysis, idiopathic muscle weakness, hand and foot numbing, polyneuropathy secondary to diabetes.
Disorders That Can Be Diagnosed with EMG
Polyneuropathy (polyneutritis, Gullian Barre and polyneuropathy)
Carpal tunnel syndrome (nerve compression at the wrist)
Ulnar tunnel syndrome (nerve compression at the elbow)
Nerve root copmression due to spinal and cervical disc herniation
Nerve compression (entrapment neuropathy)
Perinatal nerve injuries
Nerve injury, crush and avulsions
Nerve involvement due to diabetes (polyneuropathy)
Motor neuron diseases (anterior horn disease, amyotrophic lateral sclerosis)
Congenital and developmental muscle diseases (myopathy, muscular dystrophy)
Nerve compression at the neck (thoracic outlet syndrome)
Cerebrospinal disorders (Multiple sclerosis, etc.) (evoked potentials VEP, BAEP, SEP)
How Long Does It Take To Perform EMG?
EMG is a dynamic test. The physician may prolong the test and perform additional evaluations. Thus, it may take 5 minutes to 1 hour. Test for a simple nerve compression may be completed in 5-10 minutes while test for anterior horn disease may take up to 1 hour.
Is EMG a Painful Procedure?
It depends on the physician’s experience. In the hands of an experienced specialist EMG is a painless test, but an unexperienced doctor can make this test painful for the patient. Electric conduction study can be easily performed even on children. The needle EMG, although not required for every patient, is not a challenging procedure if conducted carefully.
For The Tests Performed in Our Clinic, Please See Below.
Motor Nerve Conduction Tests
It can be classified as a standard test for each EMG procedure which is performed with the measurement of motor nerve conduction volocity. It provides significant information on cases of especially nerve compressions and polyneuropathy.
Sensory nerve conduction tests
Similar to motor nerve conduction tests, it is a standard test for each EMG procedure which is performed with the measurement of sensory nerve conduction velocity. It provides significant information on cases of especially nerve compressions and polyneuropathy.
Needle EMG
A needle electrode inserted directly into a muscle records the electrical activity in that muscle. This way, we can gather direct information on the muscle diseases and the related nerves. It is not a standard test for EMG procedure.
Repetitive Nerve Stimulation
It is a test for the diseases that effect neuromuscular transmission, such as myasthenia gravis. It is performed by imposing repetitive nerve stimulation.
Single Fiber EMG
It is a very sophisticated test for the diseases that effect neuromuscular transmission, such as myasthenia gravis. The electric activity of a single muscle fiber is examined. It requires a high level of experience.
Evoked Potentials: SEP
A test that records electrical activity of the brain resulting from the stimulation of sensory nerves on the legs and arms via the electrodes placed on the head. This way, the test studies if there is any dysfunction in spinal cord and neural pathways.
Evoked Potentials: Watch the SEP Video
F-wave and H.Reflex
These are auxiliary tests recording potentials produced upon the stimulation of nerves in the spinal cord. These are especially preferred for polyneuropathy and root compressions due to disc herniations.
Blink Reflex
It is a test used for facial palsy. It provides information on the fascial nerves and the recovery potential of fascial palsy.
Paravertebral Needle EMG
The evaluation of the muscles peripheral to spinal cord. It provides information on spinal and cervical disc herniation.
Anal Sphincter EMG
It is a needle EMG method testing anal sphincter for patients with fecal incontinence.