Symptoms and causes
Types of neuropathy
Neuropathy is classified three different ways at once — by how many nerves are affected, by which fibers inside them are damaged, and by what caused it. Knowing which axis someone is talking about is what makes the word useful.
Written by the Managing Neuropathy editorial team under the direction of Dr. Tom Biernacki, DPM, FACFAS · Clinical review pending · Last updated 7 September 2026
The short answer. “Neuropathy” only means nerve damage. A useful description answers three questions: how many nerves (one, several scattered, or all the longest ones), which fibers (sensory, motor, autonomic, and large or small), and why. The commonest picture by far is a distal symmetric sensory polyneuropathy — both feet, worst at the toes, sensory first — and diabetes is its commonest cause.
Axis one: how many nerves
| Pattern | What it means | Typical example |
|---|---|---|
| Mononeuropathy | One named nerve, usually compressed or injured at a specific point | Carpal tunnel at the wrist; peroneal nerve at the outside of the knee; tarsal tunnel at the inner ankle; Baxter’s nerve in the heel |
| Mononeuritis multiplex | Several separate named nerves, in a patchy, asymmetric way | Vasculitis, and some infections — an important pattern because it points away from the ordinary causes |
| Polyneuropathy | Many nerves at once, symmetrically, longest first | Diabetic, alcohol-related, chemotherapy-related, B12 deficiency, idiopathic |
| Radiculopathy | A nerve root as it leaves the spine, not a peripheral nerve at all | A lumbar disc pressing on L5 — a frequent impostor |
The distinction matters immediately. One nerve suggests something local and often relievable. Many nerves symmetrically suggests something systemic — metabolic, toxic or nutritional. A patchy asymmetric pattern is the one that should prompt a wider search.
Axis two: which fibers
A peripheral nerve is a bundle of fiber types, and disease does not damage them evenly. This is the axis that explains why symptoms differ so much between people with the same diagnosis.
- Sensory neuropathy — the commonest. Tingling, burning, numbness. The full symptom list is here.
- Motor neuropathy — weakness, tripping, cramps, toes that claw as the small foot muscles fail.
- Autonomic neuropathy — blood pressure, digestion, bladder and sweating. Covered in full here.
- Sensorimotor, or all three together, which is what most long-standing polyneuropathies eventually become.
Cutting the same bundle a different way:
- Small-fiber damage produces burning, stabbing, temperature confusion and sweating changes, and it can leave nerve conduction studies completely normal. Why that normal test is so misleading.
- Large-fiber damage produces numbness, lost vibration sense, poor balance and absent ankle reflexes — quieter, and more dangerous in a foot.
There is one more technical split worth recognising because it appears on reports: axonal neuropathy, where the nerve fiber itself dies back from the tip, versus demyelinating, where the insulating sheath is damaged. Most metabolic and toxic neuropathies are axonal and length-dependent. Demyelinating patterns raise the possibility of an immune-mediated cause, which is a different treatment conversation entirely.
Axis three: the cause
Metabolic and endocrine
Diabetes is the leading cause in this country, and prediabetes accounts for a meaningful share of neuropathy previously labelled idiopathic. The four diabetic patterns are here. Thyroid disease and chronic kidney disease also contribute.
Toxic
Alcohol, in a dose-related way and often with a nutritional deficiency alongside it. Chemotherapy, particularly the platinum agents, taxanes and vinca alkaloids, sometimes appearing or worsening after treatment ends. And, more often than people expect, high-dose vitamin B6, which causes a sensory neuropathy at sustained high intake and turns up in exactly the supplements marketed for nerve health. That trap is covered here.
Nutritional
B12 deficiency is the one worth chasing hardest because correcting it changes the course. Long-term metformin and long-term acid-suppressing medicines both lower B12. Deficiencies of folate, thiamine, copper and vitamin E can each do it too.
Autoimmune and inflammatory
Guillain-Barré syndrome, which develops over days and is an emergency; its chronic relative CIDP, which is important because it is treatable; vasculitis; and neuropathy accompanying rheumatoid disease, lupus or Sjögren’s syndrome.
Infectious
Shingles, HIV, Lyme disease, hepatitis C, and leprosy, which remains the leading infectious cause worldwide.
Hereditary
Charcot-Marie-Tooth disease is the commonest inherited neuropathy. It often shows itself in the foot: very high arches, clawed toes, ankles that turn easily, and a family history that nobody had connected. In podiatry it is the diagnosis to consider when a young adult has a foot shape that does not match their story.
Compressive and traumatic
A nerve squashed at a predictable point. In the lower limb the usual suspects are the peroneal nerve at the outside of the knee, the tibial nerve inside the ankle, and Baxter’s nerve in the heel. People with diabetes are more susceptible to all of these, because a metabolically stressed nerve tolerates pressure poorly.
Idiopathic
After a proper workup, a substantial share of cases have no identified cause. That label should be earned rather than assumed — it is worth knowing whether glucose tolerance, B12, thyroid function and a paraprotein screen were actually checked before the word is used.
The one pattern that accounts for most of it
Put the three axes together and the commonest single presentation is a distal symmetric sensory-predominant axonal polyneuropathy: both feet, worst at the toes, sensory before motor, slow over years, small and large fibers in varying mixture. That is what most people mean when they say “neuropathy in the feet.” The full page on it is here.
The value of the classification is in the exceptions. A neuropathy that is one-sided, patchy, motor-first, rapidly progressive, or that started in the hands is telling you it does not belong to that common group — and that changes what should be tested.
Why the type changes what happens next
Whatever the type, the foot consequences converge: reduced sensation, changed shape, altered pressure. Treatment is here, and protection is here.
Common questions
What is the most common type of neuropathy?
Distal symmetric polyneuropathy — both feet, starting at the toes, sensory symptoms first — with diabetes as its leading cause.
Is peripheral neuropathy the same as polyneuropathy?
Not quite. Peripheral neuropathy means damage to nerves outside the brain and spinal cord, which includes single-nerve problems. Polyneuropathy specifically means many nerves affected at once, symmetrically.
My report says “axonal.” What does that mean?
That the nerve fiber itself is damaged rather than its insulating sheath. It is the usual finding in metabolic and toxic neuropathies, and it fits the pattern that begins at the toes.
Can you have more than one type at once?
Frequently. A common combination is a generalised diabetic polyneuropathy plus a compressed nerve at a pressure point, because a metabolically stressed nerve is less tolerant of pressure. It is one reason a new one-sided symptom in someone with long-standing neuropathy deserves a fresh look rather than being folded into the old diagnosis.
What does “idiopathic” really mean?
That no cause was found. It is a reasonable conclusion after a thorough workup and a poor one before it. Ask which tests were done.
Related reading
Neuropathy in the feet · The full symptom list · Diabetic neuropathy · Small fiber neuropathy · Autonomic neuropathy · Alcohol-related neuropathy · Radiculopathy versus neuropathy · Foot drop · Baxter’s neuropathy
Sources and further reading: American Academy of Neurology guidance on the evaluation of distal symmetric polyneuropathy. National Institute of Neurological Disorders and Stroke, peripheral neuropathy fact sheet. American Diabetes Association Standards of Care, neuropathy section. Published reviews of hereditary neuropathies and of chemotherapy-induced peripheral neuropathy.
This page is general education and is not a diagnosis or a treatment plan. Clinical review by Dr. Biernacki is pending; the review date will be shown here once complete.
For our Michigan neighbors
Which type you have
changes what to do.
Pattern, distribution, reflexes, sensation and circulation — the examination that separates the common picture from the ones that need a wider search. Dr. Biernacki’s Michigan practice does it.
Everywhere else, take this page to your own clinician.
Dr. Tom Biernacki, DPM, FACFAS is a double board-certified foot and ankle surgeon (ABFAS and ABPM) and a Fellow of the American College of Foot & Ankle Surgeons. He is the founder of Balance Foot & Ankle in Howell and Bloomfield Township, Michigan, where peripheral neuropathy, diabetic foot risk and loss of protective sensation are part of his weekly clinic. His patient education videos have drawn more than 950,000 subscribers on YouTube. He writes Managing Neuropathy to put the explanation he gives in the exam room in front of the people who cannot get to one — including when a product is worth buying and when it is not.