Electroneuromyography (ENMG): what the test is, what happens and what it shows
Numbness, tingling, burning or weakness in the arms or legs, or pain radiating from the neck or lower back into a limb may lead a doctor to prescribe ENMG. Below, we explain what the test is, what it can show and how to prepare.
What is ENMG?
Electroneuromyography examines peripheral nerves and muscles. It tests the nerves of the arms, legs and face, nerve roots, transmission of signals from nerves to muscles, and the muscles themselves. ENMG has two parts.
- Nerve conduction studies (nerve conduction studies). Adhesive electrodes are placed on the skin, a brief, weak impulse is delivered to a nerve, and the equipment records the response. This assesses how quickly and effectively the nerve conducts a signal.
- Needle EMG. A thin needle electrode is inserted into a muscle to record its electrical activity at rest and during contraction. This helps distinguish nerve damage from damage to the muscle itself.
At SPRAVNO, both parts are available, including within a single examination. The doctor decides which nerves and muscles to test and whether needle EMG is needed.
When is ENMG prescribed?
SPRAVNO doctors recommend ENMG when there are signs of peripheral nerve or muscle dysfunction:
- numbness, tingling, burning or reduced sensation in the arms or legs;
- muscle weakness, loss of muscle bulk, difficulty holding objects or walking;
- neck or lower back pain radiating into a limb, accompanied by numbness or weakness;
- changes in sensation or movement after a nerve injury.
Studies in ENMG laboratories in Mexico, Turkey, Korea, Italy and Ethiopia report the same most common reasons for referral: carpal tunnel syndrome (12–62% of referrals), polyneuropathy (up to 34%) and radiculopathy — nerve root damage (10–35%).
A symptom alone is not a diagnosis and does not mean ENMG is needed. The test is always prescribed by a doctor.
What ENMG does and does not show
ENMG helps clarify the exact location, nature and severity of a problem. The results can help the doctor distinguish damage to the nerve’s covering from damage to the nerve fibres themselves and assess the prognosis.
Limitations of the test:
- ENMG does not assess the brain or spinal cord. It therefore does not diagnose conditions such as multiple sclerosis, which is diagnosed using MRI and other methods.
- Standard ENMG does not detect small-fibre nerve damage: results may be normal in this type of neuropathy.
- Nerve conduction studies alone are insufficient to assess a nerve root: needle EMG is needed, and even that does not detect radiculopathy in every case.
ENMG and MRI do not replace each other. MRI shows structure — the spine, a disc herniation and tissues — while ENMG shows nerve and muscle function. MRI often detects changes that cause no symptoms, and it does not assess polyneuropathy.
Studies in ENMG laboratories report normal results in 25–38% of patients. The medical conclusion is always assessed alongside symptoms and examination findings.
What happens during the test
- The doctor asks about your symptoms, reviews the referral and previous test results, and determines the scope.
- Nerve conduction studies: electrodes on the skin and brief impulses. These feel like tingling or muscle twitching — uncomfortable, but usually not painful.
- Needle EMG, if needed: a single-use needle electrode is inserted into several muscles. Insertion causes discomfort like an injection, which passes shortly after the needle is removed. Medical intervention is performed only with the patient’s consent, as required by Article 43 of the Fundamentals of Ukrainian Legislation on Health Care.
- The doctor explains the results during the test, and you receive the medical report immediately.
The test can take up to 2 hours, depending on its type and scope. If anything is uncomfortable, say so and the test will be stopped or paused.
After the test, you can return to your usual activities immediately, including driving. After needle EMG, the muscles may feel tender for a few days and a small bruise may develop. If pain at the needle site increases, or swelling or pus develops, contact a doctor.
What an ENMG report looks like
The report includes tables for each nerve and muscle, limb temperature, reference values and a medical conclusion; tracings are included when needed. The diagrams below explain the main measurements.
| Nerve | Latency, ms | Amplitude, mV | Velocity, m/s |
|---|---|---|---|
| Median | |||
| Ulnar | |||
| Tibial |
| Muscle | Spontaneous activity | Motor units |
|---|---|---|
| — | ||
| — |
Illustrative diagrams, not an actual test.
How to prepare
- On the day of the test, do not apply creams, oils or lotions to the areas being examined.
- Wear loose clothing to allow easy access to your arms and legs.
- Keep your limbs warm: wear gloves and warm socks in cold weather.
- Eat and drink as usual; you do not need to fast.
- Do not stop medicines on your own. If the test is to diagnose myasthenia, ask your doctor in advance how to take your medicines.
- Bring your referral, previous ENMG reports, neurologist reports, other test results and a list of medicines.
Why warmth matters: cooling a limb slows nerve signal conduction — velocity falls by 1.5–2.5 m/s for each degree of cooling, which can make the result appear worse than it is.
Safety and precautions
- Tell the doctor in advance about a pacemaker, implanted defibrillator or neurostimulator. Nerve conduction studies are usually safe with modern pacemakers.
- Medicines that reduce blood clotting are not routinely stopped, but you must tell the doctor about them and any bleeding disorder, especially before needle EMG. Significant bleeding occurs in fewer than 1 in 10 000 tests.
- The needle is not inserted into an area with an active infection. Report any wounds, rash or skin inflammation in the test area before the examination begins.
- Pregnancy alone is not a contraindication to the test.
- Needle electrodes are single-use.
ENMG after a nerve injury or wound
In the first week after an injury, ENMG may show the location of the damage and whether it is complete.
Signs of nerve fibre damage appear on ENMG 2–4 weeks after injury; earlier testing is performed only at the doctor’s discretion.
After 3–4 months, repeat ENMG shows whether there are signs of recovery. If there are none, doctors suspect complete nerve rupture and discuss surgery.
Motor recovery usually reaches a plateau after 18–24 months, so patients with severe injuries are referred to a surgeon early.
At the Romodanov Institute of Neurosurgery, researchers examined 480 patients with gunshot and mine-blast injuries to limb nerves, performing 1400 ENMG and EMG tests (Ukrainian Neurosurgical Journal, 2024). One of the co-authors is SPRAVNO doctor Oksana Mytsak.
Repeat ENMG
Repeat testing is performed to assess changes over time: after an injury, with new symptoms, when the diagnosis is unclear or the first test was incomplete.
Bring previous reports: the medical conclusion describes changes compared with the previous test.
In trials, different doctors measuring the same nerves obtained noticeably different values; standardising the technique reduces variation. For comparison, it is therefore important that the same testing method is used.
Sources
- StatPearls (NCBI). Nerve Conduction Studies and Electromyography, 2025. ncbi.nlm.nih.gov
- StatPearls (NCBI). Peripheral Nerve Injury, 2026. ncbi.nlm.nih.gov
- Ministry of Health of Ukraine, guidelines portal. Guideline 00738 “Clinical neurophysiology in diagnosis”. guidelines.moz.gov.ua
- AANEM. FAQs Before EDX Testing; Reporting the Results of NCS and Needle EMG (2026); Patient Safety: EMG/NCS and Risk of Bleeding (2021). aanem.org
- AANEM. Recommended Policy for Electrodiagnostic Medicine, 2023. aanem.org
- Mayo Clinic. Electromyography (EMG). mayoclinic.org
- Johns Hopkins Medicine. Electromyography; Nerve Conduction Studies. hopkinsmedicine.org
- Cambridge University Hospitals NHS. Nerve conduction studies and electromyography, 2026. cuh.nhs.uk
- NINDS (NIH). Multiple Sclerosis, 2025. ninds.nih.gov
- Callaghan BC et al. Electrodiagnostic tests in polyneuropathy and radiculopathy. JAMA, 2016. pmc.ncbi.nlm.nih.gov
- Gechev A et al. Potential risks of iatrogenic complications of NCS and EMG. Clin Neurophysiol Pract, 2016. pmc.ncbi.nlm.nih.gov
- Hearn SL et al. Serial electrodiagnostic testing. Muscle Nerve, 2024; Dyck PJ et al., 2013; Litchy WJ et al., 2014 — reproducibility of measurements.
- López-López et al., Diagnostics, 2025; Korean J Yeungnam Med Sci, 2024; Functional Neurology, 2014; Clin Neurophysiol Pract, 2022 — reasons for ENMG referral. pmc.ncbi.nlm.nih.gov
- Solonovych O. et al. ENMG in the long-term consequences of gunshot and mine-blast injuries to limb nerves. Ukrainian Neurosurgical Journal, 2024. theunj.org
- Fundamentals of Ukrainian Legislation on Health Care, Article 43. zakon.rada.gov.ua
