Nerve conduction studies (NCS) and electromyography (EMG) test how well your nerves and muscles work. In an NCS, small sticky pads are placed on the skin and a nerve is stimulated with brief, mild electrical pulses. The machine measures how fast and how strongly the signal travels. In an EMG, a very thin needle is placed in a muscle to record its electrical activity at rest and when you tense it. The two are often done at the same visit.
They help doctors investigate numbness, tingling, weakness or nerve pain. Common reasons include peripheral neuropathy, carpal tunnel syndrome, a trapped nerve root in the neck or back, muscle disease and suspected motor neurone disease. They have real blind spots, though. The most important is small-fibre neuropathy, which a standard NCS usually does not detect.
The US National Library of Medicine explains what an abnormal NCS can point to. One pattern is damage to the long part of the nerve fibre, the axon. Another is damage to the myelin, the fatty insulation around the nerve. A third is a "conduction block", where the signal is stopped somewhere along the nerve. These patterns help narrow down the cause.
The NHS says people with suspected peripheral neuropathy may see a neurologist for further tests, including NCS and EMG. These help confirm a neuropathy and show its pattern. Finding the cause is a separate step. The NHS says a GP can usually identify it, often with blood tests for causes such as diabetes or vitamin B12 deficiency. The causes of numb or burning feet worth looking for are covered in our neuropathy guide.
Carpal tunnel syndrome affects the median nerve in the wrist and hand. A nerve test is not automatically part of the diagnosis. The NHS says a health professional who is unsure it is carpal tunnel syndrome may refer you for a nerve conduction test. Tallaght University Hospital in Dublin describes nerve entrapment, frequently carpal tunnel syndrome, as one of the main reasons its department does NCS.
Radiculopathy means a nerve root is affected as it leaves the spine, usually in the neck or lower back. Here the needle EMG does most of the work. A 2020 review in Muscle & Nerve calls EMG the most important electrical test for radiculopathy. It describes the test as having modest sensitivity but high specificity. In plain terms, an abnormal result is a strong pointer. A normal result does not rule a trapped nerve root out.
A 2019 handbook chapter adds a useful detail. It says preserved sensory nerve signals help place the problem at the nerve root, rather than further down the limb.
Motor neurone disease (MND) affects the nerve cells that control muscles. The NHS says tests to check how well your nerves are working are among those used to help diagnose it. EMG can detect involvement of the lower motor neurons before it is obvious on examination, according to a 2026 review. The same review says diagnosis remains primarily clinical, with EMG and imaging in a supporting role.
The NHS also says MND can be difficult to diagnose in the early stages. NICE, the guideline body for England, advises that people with suspected MND should be referred to a neurologist without delay. It also says they should get information and support during periods of uncertainty.
EMG helps tell muscle disease from nerve disease. The US National Library of Medicine lists muscular dystrophies, polymyositis and dermatomyositis among the conditions that can give abnormal EMG results. It also lists myasthenia gravis and Lambert-Eaton syndrome, which affect the junction between nerve and muscle. Specialised versions of the test exist. For example, Tallaght University Hospital lists single-fibre EMG among its services.
The tests can be uncomfortable. A patient leaflet from Hull University Teaching Hospitals NHS Trust compares the NCS pulses to a TENS machine, which feels like tingling. It says the sensations are not harmful and stop when the test ends. The skin may go slightly red from preparation, which fades quickly.
For the needle EMG, the US National Library of Medicine says you may feel some pain or discomfort as the needles go in. Most people complete the test without problems. The muscle may feel tender or bruised for a few days. The Hull leaflet mentions a small amount of bleeding and a small chance of local bruising.
How long it takes varies. St Vincent's University Hospital in Dublin says its studies usually last under 30 minutes. The Hull leaflet says NCS and EMG together take about 30 to 60 minutes.
These points come from the Hull NHS leaflet and the US National Library of Medicine. Always follow your own department's letter.
According to the Hull leaflet, you can usually carry on as normal afterwards, including driving.
This is the limit people most need to know. Small nerve fibres carry pain and temperature sensation, and they help control automatic body functions. Small-fibre neuropathy affects these fibres.
A standard NCS is built to assess larger fibres. A 2025 review notes that these standard tests come back normal in small-fibre neuropathy. A 2026 review by the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM) makes the same point. It describes small-fibre neuropathy as nerve pain, altered sensation and autonomic symptoms with normal nerve conduction studies. So a normal NCS does not rule it out if your symptoms are burning pain or temperature changes.
Other tests look at small fibres instead. The main one is a skin biopsy, usually from the lower leg, which counts the nerve fibres in the skin. A 2010 European guideline rates it as reliable for diagnosing small-fibre neuropathy. The AANEM review calls skin biopsy the most validated direct test. It also says no single test is accurate enough to stand alone. Some neurophysiology departments also test how well you sense temperature changes. St Vincent's University Hospital mentions this.
At St Vincent's University Hospital, a clinical physiologist or a clinician does the test. A consultant in clinical neurophysiology then interprets and reports every study. The Hull leaflet says results go to your referring doctor, usually within up to two weeks.
The report usually lists which nerves and muscles were tested, and whether results were normal. Where they are not, it may describe the pattern: damage to the nerve fibre, to its insulation, or to the muscle. Ask the doctor who referred you to explain what it means for you.
NCS and EMG are done in hospital clinical neurophysiology departments. For example, the HSE lists a neurophysiology service at University Hospital Limerick for adults and children, with referral by a consultant or GP. St Vincent's University Hospital and Tallaght University Hospital in Dublin also run departments. Waiting times vary and we could not find a current national figure. If you are considering a private test and have health insurance, check what it covers first.
The tests are done in hospital. For carpal tunnel syndrome, the NHS says a health professional may refer you when the diagnosis is uncertain. For neuropathy, it says some people may need to see a neurologist in hospital for further tests.
A clinician orders the tests. Check cover with your insurer before booking.
Some nerve symptoms need urgent care, not a routine appointment. The NHS says Guillain-Barré syndrome is serious and needs urgent hospital treatment. It often starts with tingling or numbness in the hands and feet, followed by weakness. Ask for an urgent GP appointment, or call NHS 111 in England, if you think you have it.
The NHS says to call 999 or go to A&E if your face droops on one side or you have trouble swallowing or speaking. The same applies if you cannot lift one or both arms. These can be signs of a stroke. If you are struggling to breathe, call an ambulance. In Ireland, phone 112 or 999. In the UK, phone 999. In the US, phone 911. How to recognise a stroke is covered separately.
It can be uncomfortable. The pulses feel like brief tingling or a small shock. The needle EMG can hurt a little as it goes in, and the muscle may be sore for a few days.
The Hull NHS leaflet says you can carry on as normal, including driving. Check with your own department if you are unsure.
A normal NCS does not rule out small-fibre neuropathy. Ask the doctor who referred you whether small-fibre tests, such as a skin biopsy, are appropriate. Ask too whether the causes have been checked with blood tests.
Do not stop it on your own. Tell the team before the test that you take it. The Hull leaflet says to take your medication as normal unless your doctor tells you otherwise.
Often up to two weeks, according to the Hull NHS leaflet, though this varies. The report goes to the doctor who referred you.
This article is general information, not medical advice. It cannot diagnose a nerve or muscle condition. Talk to your GP or specialist about your own symptoms and results.
Reviewed by: Proco Team
Last updated: November 2026