Peripheral Neuropathy: Symptoms, Causes, and Treatment

Intro

The peripheral nervous system consists of all the nerves outside the brain and spinal cord — the network that carries signals between the central nervous system and the rest of the body, controlling movement, sensation, and many automatic functions. When these nerves are damaged, the result is peripheral neuropathy.

Peripheral neuropathy is not a single disease but a term for dozens of conditions that share the common feature of peripheral nerve dysfunction. It affects an estimated 2–3% of the general population, rising to 8% over the age of 55. In people with diabetes, prevalence exceeds 50%.

Symptoms range from mild and manageable to severely disabling. The most important steps are identifying the underlying cause (many are treatable), managing pain, and protecting affected areas — particularly the feet — from injury.

Key Points

Peripheral neuropathy most commonly presents as numbness, tingling, burning pain, and weakness beginning in the feet and/or hands.
Diabetes is the single most common cause worldwide; alcohol, B12 deficiency, chemotherapy, and autoimmune conditions are also important.
Around 25–30% of cases remain idiopathic (no cause identified) after thorough investigation.
Nerve conduction studies (NCS) and electromyography (EMG) are the key diagnostic tests for large-fibre neuropathy; skin biopsy is used for small-fibre neuropathy.
Treating the underlying cause is the priority — some neuropathies are partially or fully reversible if caught early.
Neuropathic pain is managed with specific agents: amitriptyline, duloxetine, gabapentin, and pregabalin are first-line.
Falls prevention and foot care are critical management components, particularly in diabetic neuropathy.

Background

Peripheral nerve anatomy

Peripheral nerves are composed of different fibre types:

Fibre type	Myelin	Function	Affected in
Large myelinated (Aβ)	Heavy	Vibration, light touch, proprioception	Large fibre neuropathy
Large motor (Aα)	Heavy	Voluntary muscle control	Motor neuropathy
Small myelinated (Aδ)	Thin	Sharp pain, temperature	Small fibre neuropathy
Small unmyelinated (C)	None	Dull pain, temperature, autonomic	Small fibre, autonomic neuropathy

Different diseases preferentially affect different fibre types, explaining the varied symptom patterns.

Distribution patterns

Length-dependent polyneuropathy — the most common pattern; longest nerves affected first, so symptoms start in the feet and gradually ascend. A “glove-and-stocking” distribution.
Mononeuropathy — damage to a single peripheral nerve (e.g., carpal tunnel syndrome = median nerve; peroneal nerve palsy = foot drop).
Mononeuritis multiplex — multiple individual nerves affected, often asymmetrically; suggests vasculitic or infiltrative causes.
Proximal neuropathy — affects thigh, hip, and proximal muscles; seen in diabetic amyotrophy and some inflammatory conditions.
Autonomic neuropathy — affects nerves controlling internal organs; causes orthostatic hypotension, bladder dysfunction, gastroparesis, impaired sweating.

Causes

Diabetes mellitus

Diabetic peripheral neuropathy is the most common cause of peripheral neuropathy worldwide, affecting over 50% of people with long-standing diabetes. It results from sustained hyperglycaemia damaging small blood vessels supplying nerves (vasa nervorum) and from direct glycation of nerve proteins.

Risk increases with:

Duration of diabetes
Poor glucose control (high HbA1c)
Co-existing hypertension, dyslipidaemia, and smoking

Early diabetic neuropathy may be asymptomatic. Advanced neuropathy causes significant pain and loss of protective sensation, placing feet at major risk of injury and ulceration. See Diabetic Neuropathy and Nerve Damage for a detailed guide.

Alcohol

Chronic heavy alcohol consumption is a leading cause of polyneuropathy, through direct neuronal toxicity and nutritional deficiencies (thiamine, B12, folate). Features are similar to diabetic neuropathy — predominantly distal sensory, often painful.

Vitamin B12 deficiency

B12 is essential for myelin synthesis. Deficiency — from malabsorption (pernicious anaemia, post-gastrectomy, bariatric surgery), inadequate intake (vegan/vegetarian diets without supplementation), or metformin use — causes subacute combined degeneration of the spinal cord and peripheral neuropathy. Early diagnosis and replacement can prevent permanent damage.

Chemotherapy-induced peripheral neuropathy (CIPN)

Many chemotherapy agents are neurotoxic:

Platinum agents (cisplatin, oxaliplatin, carboplatin) — primarily sensory; may cause “coasting” (worsening after treatment ends)
Taxanes (paclitaxel, docetaxel) — sensory and motor
Vinca alkaloids (vincristine, vinblastine) — predominantly motor

CIPN can limit cancer treatment dosing and persist after treatment completion.

Hereditary neuropathies

Charcot-Marie-Tooth disease (CMT) is the most common inherited peripheral neuropathy (~1 in 2,500). It typically presents in adolescence or early adulthood with progressive distal weakness and foot deformity (high arches, hammer toes). Numerous genetic subtypes. No disease-modifying treatment currently, but physiotherapy, bracing, and orthopaedic surgery help.

Inflammatory and autoimmune neuropathies

Guillain-Barré syndrome (GBS) — acute, rapidly progressive ascending weakness and areflexia, often following infection. Medical emergency — can progress to respiratory failure. Treatment: IVIG or plasma exchange. Recovery over months; most recover well but some have residual deficits.
Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) — chronic, relapsing form analogous to GBS. Responds to corticosteroids, IVIG, and plasma exchange.
Vasculitic neuropathy — neuropathy from inflammation of blood vessels; often presents as mononeuritis multiplex. Associated with rheumatoid arthritis, ANCA-associated vasculitis, polyarteritis nodosa.
Paraproteinaemic neuropathy — from MGUS (monoclonal gammopathy of undetermined significance) or plasma cell dyscrasias (myeloma, POEMS syndrome).

Other causes

Cause	Notes
Hypothyroidism	Readily treatable; often improved with thyroxine
Chronic kidney disease	Uraemic neuropathy; improves with dialysis or transplant
HIV infection	Both from virus itself and antiretroviral neurotoxicity
Lyme disease	Variable; may respond to antibiotics
Sarcoidosis	Granulomatous infiltration of nerves
Paraneoplastic	Antibodies produced against tumour cross-react with nerve antigens

Idiopathic neuropathy

After thorough investigation, approximately 25–30% of peripheral neuropathies remain without identified cause (idiopathic). Many of these are small-fibre predominant. Prognosis is generally stable or slowly progressive.

Diagnosis

Clinical assessment

The neurological examination identifies:

Distribution of sensory loss (distal, proximal, dermatomal)
Loss of reflexes (particularly ankle jerks) — characteristic of peripheral neuropathy
Weakness and its distribution
Autonomic features

Nerve conduction studies (NCS) and EMG

NCS measures the speed and amplitude of electrical signals in motor and sensory nerves. It distinguishes:

Demyelinating neuropathy — slowed conduction velocity (e.g., CIDP, CMT type 1)
Axonal neuropathy — reduced amplitude with preserved velocity (e.g., diabetic, alcohol)

EMG assesses the electrical activity of muscles and complements NCS in identifying motor involvement.

Skin biopsy

The gold-standard test for small fibre neuropathy. A 3mm punch biopsy from the distal leg is taken; reduced intra-epidermal nerve fibre density (IENFD) confirms small fibre damage. NCS is typically normal in small fibre neuropathy.

Blood tests

Systematic blood testing for treatable causes:

HbA1c and fasting glucose
Full blood count
B12 and folate
Thyroid function (TSH)
Kidney function (creatinine, eGFR)
Liver function
Fasting glucose and HbA1c
ESR and CRP
Serum protein electrophoresis (SPEP) and immunofixation
HIV testing (where relevant)
ANA and ANCA (if inflammatory aetiology suspected)

Further investigations

Genetic testing (CMT panel) if hereditary neuropathy is suspected
Lumbar puncture for GBS (elevated CSF protein with normal cell count)
CT/MRI if proximal neuropathy, radiculopathy, or paraneoplastic cause suspected
Nerve biopsy in selected cases

Treatment

Treating the underlying cause

This is the priority — and the most effective way to prevent progression:

Diabetes — optimising glucose control (HbA1c target individualised); managing blood pressure and lipids. See Diabetic Neuropathy and Nerve Damage.
B12 deficiency — intramuscular B12 injections initially, then maintenance replacement; oral supplementation for dietary deficiency
Alcohol — cessation; thiamine supplementation
Hypothyroidism — levothyroxine replacement
CIDP — IVIG, plasma exchange, corticosteroids
Vasculitic neuropathy — immunosuppression (corticosteroids, cyclophosphamide, rituximab)

Neuropathic pain management

Neuropathic pain requires specific agents — standard analgesics (paracetamol, NSAIDs, opioids) are poorly effective for most neuropathic pain.

First-line options:

Drug class	Examples	Notes
Tricyclic antidepressants	Amitriptyline, nortriptyline	Effective; anticholinergic side effects; caution in cardiac disease
SNRIs	Duloxetine, venlafaxine	Good evidence; duloxetine licensed for diabetic neuropathy
Alpha-2-delta ligands	Gabapentin, pregabalin	Widely used; dizziness, sedation common; abuse potential (pregabalin)

Second-line / adjuncts:

Topical lidocaine patches — for localised neuropathic pain
Capsaicin 8% patch — desensitises sensory fibres; specialist use
Tramadol — for moderate pain not responding to first-line
Strong opioids — last resort in refractory cases; significant caution

Combination therapy (e.g., gabapentin + duloxetine) is sometimes used for refractory pain. Starting doses should be low and titrated to effect, with specific attention to tolerability.

Physical rehabilitation

Physiotherapy — balance training, strengthening exercises, gait retraining. Essential for reducing falls risk.
Occupational therapy — aids and adaptations for daily activities; upper limb function.
Orthotics — ankle-foot orthoses (AFO) for foot drop; custom footwear for foot deformity in hereditary neuropathy.

Foot care

In neuropathy with loss of protective sensation — particularly in diabetes — meticulous foot care is essential:

Daily foot inspection for cuts, blisters, pressure sores (the patient may not feel them)
Well-fitting footwear; avoid walking barefoot
Regular podiatry input
Prompt treatment of any foot injury See Diabetic Foot Care for detailed guidance.

Falls prevention

Peripheral neuropathy — through impaired proprioception, weakness, and reduced protective reflexes — substantially increases falls risk. Strategies include:

Balance and strength exercises (tai chi has evidence)
Home environment assessment
Walking aids if required
Review of medications contributing to falls risk

Risks, Benefits, and Prognosis

Prognosis varies widely by cause:

Cause	Prognosis
B12 deficiency (treated early)	Often significant improvement
Alcohol (abstinence + nutrition)	Partial to significant improvement
Diabetic neuropathy	Can stabilise; partial improvement possible with excellent control
CIDP (treated)	Most patients respond; some require long-term maintenance
GBS	Most recover over months; ~20% have significant residual deficits
Charcot-Marie-Tooth	Slowly progressive; significant variability; rarely severely disabling
Chemotherapy-induced	Often partially resolves after treatment ends
Idiopathic	Generally stable or slowly progressive

The key determinant of outcome is usually how early the cause is identified and treated. Neuropathy from nutritional deficiencies and endocrine causes is particularly responsive to correction. Advanced structural nerve damage (demyelination with axonal loss) is less reversible.

FAQ

Q: Can peripheral neuropathy be confused with other conditions? A: Yes. Symptoms of peripheral neuropathy — particularly numbness and tingling — overlap with spinal cord conditions (radiculopathy from disc herniation; myelopathy), central nervous system causes, and vascular causes (Raynaud’s phenomenon). The neurological examination and NCS/EMG help distinguish peripheral from central and spinal causes.

Q: Why are symptoms worse at night? A: Many people with peripheral neuropathy notice that burning, tingling, and pain are worse at night. This is not fully understood but may relate to reduced distracting stimuli, cooler temperatures, and altered blood flow during inactivity. It is a very common feature of small-fibre neuropathy and diabetic neuropathy.

Q: Can exercise help peripheral neuropathy? A: Yes. Regular aerobic exercise improves nerve function in diabetic neuropathy, likely through improved blood flow and metabolic effects. Exercise also reduces pain, improves balance, and counters deconditioning. Even gentle walking or swimming may help if severe weakness or pain limits more vigorous exercise.

Q: Are there supplements that help peripheral neuropathy? A: Alpha-lipoic acid has some evidence in diabetic neuropathy (particularly intravenous formulation) but evidence for the oral form is less compelling. B-vitamin supplementation is essential if deficiency is present. There is no evidence that B vitamins help neuropathy in people without deficiency. Avoiding supplements not prescribed by your doctor is wise — some (e.g., B6 at high doses) can themselves cause neuropathy.

Q: Should I see a neurologist? A: If the cause is not clear, if neuropathy is progressing, or if symptoms are significantly affecting quality of life, a neurology referral is appropriate. Neurologists can arrange nerve conduction studies, skin biopsy for small fibre neuropathy, and specialist tests for rarer causes. For established diabetic neuropathy with stable symptoms, management often remains with the GP and diabetes team.