What is a neurophysiological test?

Author: Zhao Yanan, The First Affiliated Hospital of Zhengzhou University

Reviewer: Deng Wenjing, Chief Physician, First Affiliated Hospital of Zhengzhou University

Most people are familiar with electrocardiogram, color ultrasound, MRI and other examinations, but know very little about neuroelectrophysiological examinations. Today we will reveal to you the secrets of neuroelectrophysiological examinations!

Neuroelectrophysiological examination is an electrophysiological examination of nerves and muscles. It is a technology that records various electrical characteristics of muscles at rest, voluntary contraction, and peripheral nerve stimulation. The examination items mainly include nerve conduction and needle electrode electromyography. In addition, it also includes evoked potentials, repeated nerve stimulation, F waves, H reflexes, skin sympathetic reflexes, blink reflexes, single fiber electromyography, etc.

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1. What diseases can be diagnosed by neuroelectrophysiological examination?

Neurophysiological examination is of great value in the diagnosis of the following diseases:

(1) Mononeuropathy: median neuropathy, ulnar neuropathy, radial neuropathy, facial neuropathy, trigeminal neuropathy.

(2) Nerve root: cervical spondylosis and lumbar spondylosis.

(3) Nerve plexus: brachial plexus and lumbar plexus.

(4) Motor neuron disease: ALS and Kennedy's disease.

(5) Neuromuscular junction (myasthenia gravis, myasthenia syndrome).

(6) Myopathy (polymyositis, myotonic dystrophy, myotonia congenita, paramyotonia congenita, etc.).

2. Under what circumstances should neuroelectrophysiological examination be considered?

Neurodiagnostic testing should be considered when the following symptoms occur:

(1) Muscle weakness, atrophy, pain, and twitching are considered to be caused by lesions in the anterior horn of the spinal cord and below.

(2) Numbness of the limbs, especially partial numbness of the limbs.

(3) Paroxysmal quadriplegia.

(4) Numbness and weakness after limb fracture or trauma.

(5) Diabetic patients experience numbness, pain, and weakness in their limbs.

(6) Hearing impairment and visual impairment.

(7) Chronic intractable constipation.

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3. Under what circumstances can neuroelectrophysiological examination not be performed?

(1) Patients with bleeding tendency: The pros and cons of electromyography should be carefully evaluated. If the platelet count is less than 50×109/L, or the INR ratio is less than 1.5-2.0, the risk of bleeding increases when using needle electrodes. Needle electrode electromyography should be avoided in patients with hemophilia or other hereditary coagulation disorders.

(2) Patients with pacemakers should not undergo nerve conduction and evoked potential testing. Patients with implanted cardioverters or defibrillators should exercise caution.

(3) Patients with personality or mental abnormalities and who refuse to cooperate cannot undergo electromyography examination.

(4) Patients with heart failure, severe arrhythmias, or inability to lie flat cannot undergo electromyography.

(5) Patients whose stitches have not been removed, whose wounds have not healed, or who have severe swelling cannot undergo electromyography.

4.What should I pay attention to before the examination?

(1) Eat normally before the examination, do not eat on an empty stomach to avoid needle sickness.

(2) Wear loose clothing, remove jewelry, keep your skin clean, and keep your limbs warm to prevent low temperature from affecting the examination results.

(3) You may feel numbness, soreness, or other discomfort during the test. Some tests will cause muscle contraction, but will not cause damage to the neuromuscular tissue. Keep your limbs relaxed during the test and try to avoid mental stress.

(4) Because the examination items for each patient vary greatly (the time taken varies from 0.5 to 1 hour), electrophysiological examinations need to be scheduled in advance.

(5) Generally speaking, needle electrode electromyography in normal people will not significantly increase creatine phosphokinase. Some people measured the muscle enzyme spectrum 2 hours after the electroneurography examination and found no increase, but 6 hours later it increased 1.5 times compared to before the electroneurography examination and returned to normal after 48 hours. Therefore, it is best to test serum muscle enzymes before electromyography.

(6) It is recommended to take a bath with clean water on the day after the examination and avoid rubbing the acupuncture site.