Repetitive nerve stimulation
Repetitive Nerve Stimulation (RNS)
Repetitive nerve stimulation is a nerve conduction test in which electrical stimulation is applied to a motor nerve numerous times per second. A neurologist diagnoses neuromuscular junction disorders and distinguishes between presynaptic and postsynaptic conditions by analyzing the change in muscle electrical response (CMAP) after multiple simulations. It is often used to identify neuromuscular junction (NMJ) diseases such as Myasthenia Gravis (MG) or Lambert-Eaton Myasthenic Syndrome (LEMS).
Diseases of the neuromuscular junction (NMJ), the most prevalent of which is myasthenia gravis, are diagnosed with repetitive nerve stimulation. A decremental response (a smaller and smaller muscle response with each repetition) is abnormal and implies NMJ dysfunction. This may be confirmed further if the reaction returns to normal following the administration of edrophonium or neostigmine
How is the repetitive nerve stimulation test performed?
A recording electrode will be put on the tested muscle to record the response of your nerves to a series of repeated electrical stimuli. You may be asked to exercise the tested muscle for a few seconds to minutes in between electrical stimulation sequences. Many nerves and muscles may be evaluated depending on your symptoms and your doctor’s request, so the test may take at least 45 minutes to an hour to complete.
How should you prepare for the Repetitive Nerve Stimulation Test?
This test requires no additional preparation. Wear loose-fitting clothing, though, so that your hands, shoulders, and neck can be easily checked. Don’t apply any lotion, ointment, or cosmetics to your arms or face, and avoid wearing jewelry.
What are the possible risks of the repetitive nerve stimulation test?
RNS test is safe. During the test, you may experience some discomfort in the form of tingling and muscle twitching, but this will subside immediately.