Testing for neuropathy typically starts with a physical exam in your doctor’s office and, depending on results, may progress to electrical nerve testing, blood work, or a skin biopsy. There’s no single test that confirms neuropathy on its own. Instead, doctors layer several types of evaluation to determine whether nerve damage exists, how severe it is, and what’s causing it.
The Physical Exam
The first round of testing happens during a standard office visit. Your doctor will check your reflexes (especially at the ankle), muscle strength, and ability to detect different sensations. Two tools are commonly used together because they’re more accurate as a pair than either one alone.
The monofilament test uses a thin, flexible nylon fiber pressed against the sole of your foot. You close your eyes and say when you feel it. The fiber is calibrated to bend at exactly 10 grams of force, so if you can’t feel it, you’ve lost protective sensation. A systematic review in the Annals of Family Medicine found the sensitivity of this test ranges widely, from 41% to 93%, depending on how and where it’s applied. Specificity was better, reaching up to 100% in some studies. That wide range is exactly why doctors don’t rely on this test alone.
The tuning fork test checks vibration sense. A 128-Hz tuning fork is placed against a bony spot like your big toe or ankle. You should feel a buzzing sensation that gradually fades. If you can’t feel it at all, or it fades much faster than expected, that suggests damage to the large nerve fibers responsible for detecting vibration. Combining this with the monofilament test improves diagnostic accuracy significantly, particularly for diabetic neuropathy.
Nerve Conduction Studies and EMG
If the physical exam raises suspicion, the next step is usually electrodiagnostic testing. This consists of two parts that are often done in the same appointment and take about 30 to 60 minutes combined.
A nerve conduction study measures how fast electrical signals travel through your nerves. Your doctor places small electrode patches on your skin over the nerve being tested and delivers a mild electrical pulse. Recording electrodes on nearby muscles pick up the response. The time it takes for the signal to reach the muscle, called conduction velocity, tells your doctor whether the nerve is transmitting normally. A damaged nerve sends a slower, weaker signal.
An EMG (electromyography) goes a step further by looking at your muscles directly. A thin needle electrode is inserted into the muscle to record its electrical activity while you relax and while you contract it. A healthy muscle at rest should be electrically silent. If the needle picks up spontaneous electrical activity while you’re not moving, that’s a sign the nerve supplying that muscle is damaged.
The electrical pulses during nerve conduction studies feel like brief, sharp taps. The needle insertion during EMG causes mild discomfort similar to a blood draw. Neither test requires anesthesia, and you can drive yourself home afterward.
Blood Tests
Blood work helps identify what’s causing the neuropathy, not just whether it exists. The initial panel typically includes:
- Fasting blood glucose and HbA1c: screen for diabetes, the most common cause of peripheral neuropathy
- Vitamin B12 levels: B12 deficiency directly damages nerves; if B12 is borderline, a methylmalonic acid test can confirm true deficiency
- Thyroid-stimulating hormone (TSH): underactive thyroid can cause neuropathy
- Complete blood count and comprehensive metabolic panel: check for anemia, kidney disease, and liver dysfunction
- Erythrocyte sedimentation rate: a general marker of inflammation
If the initial round doesn’t reveal a cause, your doctor may order more targeted tests. Serum and urine protein electrophoresis with immunofixation can detect abnormal proteins in the blood (monoclonal gammopathy), which is an underrecognized cause of neuropathy that requires different treatment.
Skin Biopsy for Small Fiber Neuropathy
Standard nerve conduction studies only detect damage to large nerve fibers. If your symptoms point to neuropathy (burning pain, temperature sensitivity, abnormal sweating) but your electrical tests come back normal, the problem may involve small fibers that these tests simply can’t measure. That’s where a skin biopsy comes in.
The procedure is straightforward: a doctor takes two small, 3-millimeter punch biopsies from the skin, typically from the lower leg and mid-thigh on the same side of the body. The samples are stained with a marker that highlights tiny nerve endings in the outer layer of skin. Under a microscope, a pathologist counts the number of nerve fibers per millimeter of skin. That number is compared to published norms for your age and sex. A low count confirms small fiber neuropathy.
This is currently the most definitive test for small fiber neuropathy and can explain symptoms that other tests miss entirely.
Autonomic Nerve Testing
Neuropathy doesn’t only affect sensation and movement. It can also damage the nerves that control involuntary functions like sweating, heart rate, blood pressure, and digestion. If you’re experiencing lightheadedness when standing, abnormal sweating, or digestive problems alongside typical neuropathy symptoms, your doctor may order autonomic testing.
The most common test is the QSART (quantitative sudomotor axon reflex test), which evaluates the sweat glands controlled by small autonomic nerves. A mild electrical current is applied to the skin to stimulate sweating, and sensors measure exactly how much sweat is produced and how long it takes to appear. A delayed response or abnormal sweat volume indicates autonomic nerve damage. Tilt-table testing, which monitors your heart rate and blood pressure as you’re gradually tilted upright, may also be used to check for autonomic dysfunction affecting circulation.
Quantitative Sensory Testing
Quantitative sensory testing (QST) uses specialized devices to measure your exact thresholds for detecting vibration and temperature changes. For vibration, a stimulator delivers adjustable amplitudes at frequencies around 128 to 300 Hz, and you indicate when you first feel it. For temperature, a small metal plate called a thermode sits against your skin and gradually warms or cools until you report sensing the change or feeling pain.
QST can potentially detect sensory loss before it shows up on a standard exam. However, the American Academy of Neurology notes that QST results alone shouldn’t be used to diagnose neuropathy, because the test depends on your subjective responses. It’s most useful as one piece of a larger diagnostic picture, particularly in research settings or when tracking changes over time.
Imaging With MR Neurography
When doctors suspect a nerve is being compressed or trapped at a specific location, MR neurography (a specialized type of MRI) can actually visualize the nerve. Standard MRI scans don’t show nerves in much detail, but MR neurography uses high-resolution techniques that make individual nerves visible throughout the body. A radiologist looks for signs of injury or inflammation, such as a nerve that appears brighter or larger than normal.
This test is particularly useful for diagnosing entrapment conditions like carpal tunnel syndrome, cubital tunnel syndrome, sciatica related to piriformis compression, and thoracic outlet syndrome. It can also reveal whether muscles supplied by a damaged nerve have begun to atrophy, giving doctors a clearer picture of how long the nerve has been affected and how severe the damage is. MR neurography is typically used alongside electrical testing and physical examination rather than as a standalone diagnostic tool.
Self-Screening at Home
You can’t diagnose neuropathy at home, but you can screen for warning signs. The Ipswich Touch Test is a simple method: lightly touch the tips of the first, third, and fifth toes on each foot with your index finger for one to two seconds. If you can’t feel the touch on two or more sites, that suggests significant sensory loss worth bringing to your doctor’s attention.
Validated questionnaires also exist for tracking symptoms. The Michigan Neuropathy Screening Instrument asks about numbness, burning, and sensitivity in the feet and takes just a few minutes. For people experiencing neuropathy from cancer treatment, the Treatment-Induced Neuropathy Assessment Scale (TNAS) is a five-item self-report tool that measures symptom severity and its impact on daily functioning in about five minutes. These tools don’t replace clinical testing, but they give you and your doctor a structured way to describe what you’re feeling and monitor whether it’s getting worse.