神经传导速度

定义

神经传导速度 (NCV) is a test to see how fast electrical signals move through a nerve. 这个测试是和…一起完成的 肌电图(EMG) to assess the muscles for abnormalities.

选择的名字

NCV; Nerve conduction study (NCS)

如何执行测试

Adhesive patches called surface electrodes are placed on the skin over nerves or muscles at different spots. A very mild electrical impulse is applied via other patches or a handheld stimulator to stimulate the nerve.

The resulting electrical activity of the nerve is recorded by the electrodes. The distance between electrodes and the time it takes for electrical impulses to travel between electrodes are used to measure the speed of the nerve signals. It is normal for several different nerves to be tested.

EMG is the recording from needles placed into the muscles. This is often done during the same visit as NCV.

如何准备考试

You must stay at a normal body temperature. Being too cold alters nerve conduction and can give false results.

Tell your health care provider if you have a cardiac defibrillator or pacemaker, or other implanted device such as a deep brain stimulator. Special steps may need to be taken before the test if you have one of these devices.

Do not wear any lotions, sunscreen, perfume, or moisturizer on your body on the day of the test.

考试的感觉如何

The impulse may feel like an electric shock. You may feel some discomfort depending on how strong the impulse is. You should feel no pain once the test is finished.

Often, the nerve conduction test is followed by EMG. In this test, a needle is placed into a muscle and you are told to contract that muscle. This process can be uncomfortable during the test. You may have muscle soreness or bruising after the test at the site where the needle was inserted.

为什么要进行测试

This test is used to diagnose nerve damage or destruction. The test may sometimes be used to evaluate diseases of nerve or muscle, including:

• 肌病
• Lambert-Eaton综合症
• 重症肌无力
• 腕管综合症
• 跗骨隧道综合征
• 糖尿病性神经病
• 贝尔麻痹
• 格林-巴利综合征
• 臂plexopathy

正常的结果

NCV is related to the diameter of the nerve and the degree of myelination (the presence of a myelin sheath on the nerve fiber) of the nerve. Newborn infants have values that are approximately half that of adults. Adult values are normally reached by age 3 or 4.

Note: Normal value ranges may vary slightly among different laboratories. Talk to your provider about the meaning of your specific test results.

异常结果意味着什么

Most often, abnormal results are due to nerve damage or destruction, including:

• Axonopathy (damage to the long portion of the nerve cell)
• Conduction block (the impulse is blocked somewhere along the nerve pathway)
• Demyelination (damage and loss of the fatty insulation surrounding the nerve cell)

The nerve damage or destruction may be due to many different conditions, including:

• 酒精性神经病变
• 糖尿病性神经病
• Nerve effects of uremia (from kidney failure)
• 神经的创伤性损伤
• 格林-巴利综合征
• 白喉
• 腕管综合症
• 臂plexopathy
• Charcot-Marie-Tooth disease (hereditary)
• Chronic inflammatory polyneuropathy
• Common peroneal/fibular nerve dysfunction
• 远端正中神经功能障碍
• 股神经功能障碍
• Friedreich共济失调
• Mononeuritis multiplex (multiple mononeuropathies)
• 原发性淀粉样变
• 桡神经功能障碍
• 坐骨神经功能障碍
• 继发性系统性淀粉样变性
• 感觉运动多神经病
• 胫神经功能障碍
• 尺神经功能障碍

Any peripheral neuropathy can cause abnormal results. Damage to the spinal cord and disk herniation (herniated nucleus pulposus) with nerve root compression can also cause abnormal results.

注意事项

An NCV test shows the condition of the best surviving nerve fibers. Therefore, in some cases the results may be normal, even if there is nerve damage.

参考文献

德卢卡GC，格里格斯RC. Approach to the patient with neurologic disease. 参见:Goldman L, Schafer AI主编. Goldman-Cecil医学. 26日艾德. Philadelphia, PA: Elsevier; 2020:chap 368.

Nuwer先生，Pouratian N. Monitoring of neural function: electromyography, nerve conduction, and evoked potentials. In: win HR, ed. Youmans and Winn Neurological Surgery. 8日艾德. Philadelphia, PA: Elsevier; 2023:chap 274.