Topic breakdown

1. Definition, anatomy of the peripheral nerve and classification (mononeuropathy, mononeuritis multiplex, polyneuropathy, radiculopathy, plexopathy, cranial neuropathy; axonal vs demyelinating; motor, sensory, autonomic)
2. Pathophysiology: Wallerian degeneration, segmental demyelination, axonal degeneration, and Seddon and Sunderland nerve injury grades (neurapraxia, axonotmesis, neurotmesis)
3. Clinical approach: history, examination, and investigations (nerve conduction studies, EMG, CSF, nerve biopsy, blood tests, genetic tests)
4. Diabetic neuropathies: distal symmetric polyneuropathy, autonomic neuropathy, amyotrophy, mononeuropathies, and painful neuropathy
5. Immune-mediated neuropathies: Guillain-Barré syndrome and variants, CIDP, multifocal motor neuropathy, and paraproteinaemic neuropathy
6. Infective neuropathies: leprosy, HIV, diphtheria, herpes zoster and postherpetic neuralgia, Lyme disease
7. Toxic, nutritional and drug-induced neuropathies: alcohol, B12, B1 (beriberi), B6, isoniazid, vincristine, platinum agents, heavy metals (lead, arsenic), and organophosphates
8. Hereditary neuropathies: Charcot-Marie-Tooth (CMT) disease, HNPP, hereditary sensory and autonomic neuropathies, and porphyria
9. Systemic and metabolic causes: uraemia, hypothyroidism, vasculitic neuropathy, amyloidosis, sarcoidosis, paraneoplastic neuropathy, and critical illness polyneuropathy
10. Entrapment and focal mononeuropathies: carpal tunnel, ulnar, radial, common peroneal, meralgia paraesthetica, and tarsal tunnel
11. Cranial neuropathies: Bell's palsy, trigeminal neuralgia, and others
12. Management: treat the cause, neuropathic pain drugs (gabapentinoids, TCAs, SNRIs, topical agents), IVIG and plasmapheresis, steroids, rehabilitation, and foot care

Brief overview

Topic breakdown

1. Definition, anatomy of the peripheral nerve and classification (mononeuropathy, mononeuritis multiplex, polyneuropathy, radiculopathy, plexopathy, cranial neuropathy; axonal vs demyelinating; motor, sensory, autonomic)
2. Pathophysiology: Wallerian degeneration, segmental demyelination, axonal degeneration, and Seddon and Sunderland nerve injury grades (neurapraxia, axonotmesis, neurotmesis)
3. Clinical approach: history, examination, and investigations (nerve conduction studies, EMG, CSF, nerve biopsy, blood tests, genetic tests)
4. Diabetic neuropathies: distal symmetric polyneuropathy, autonomic neuropathy, amyotrophy, mononeuropathies, and painful neuropathy
5. Immune-mediated neuropathies: Guillain-Barré syndrome and variants, CIDP, multifocal motor neuropathy, and paraproteinaemic neuropathy
6. Infective neuropathies: leprosy, HIV, diphtheria, herpes zoster and postherpetic neuralgia, Lyme disease
7. Toxic, nutritional and drug-induced neuropathies: alcohol, B12, B1 (beriberi), B6, isoniazid, vincristine, platinum agents, heavy metals (lead, arsenic), and organophosphates
8. Hereditary neuropathies: Charcot-Marie-Tooth (CMT) disease, HNPP, hereditary sensory and autonomic neuropathies, and porphyria
9. Systemic and metabolic causes: uraemia, hypothyroidism, vasculitic neuropathy, amyloidosis, sarcoidosis, paraneoplastic neuropathy, and critical illness polyneuropathy
10. Entrapment and focal mononeuropathies: carpal tunnel, ulnar, radial, common peroneal, meralgia paraesthetica, and tarsal tunnel
11. Cranial neuropathies: Bell's palsy, trigeminal neuralgia, and others
12. Management: treat the cause, neuropathic pain drugs (gabapentinoids, TCAs, SNRIs, topical agents), IVIG and plasmapheresis, steroids, rehabilitation, and foot care

Brief overview

Neuropathies: Full Exam Notes (50 marks)

1. Definition and epidemiology (3 marks)

• Prevalence rises with age. It is 2-3% at 50-60 years, about 13% at 70-80 years, and over 30% above 80 years (Goldman-Cecil Medicine).
• Diabetes is the commonest cause and accounts for about 50% of polyneuropathy. Most of the rest is cryptogenic sensory neuropathy, and over half of those patients have prediabetes (Goldman-Cecil Medicine).
• Other common causes are genetic, inflammatory, metabolic and toxic.

2. Anatomy relevant to neuropathy (3 marks)

• Motor neurons: cell bodies lie in the ventral horn and axons run through the ventral roots to the muscle.
• Sensory neurons: cell bodies lie in the dorsal root ganglia (DRG). A lesion of the cell body is a neuronopathy (ganglionopathy).
• Fibre types:
  • Large myelinated fibres carry motor function, proprioception and touch.
  • Small, thinly myelinated and unmyelinated fibres carry pain, temperature and autonomic function.
• Clinical consequences:
  • Burning pain suggests small-fibre injury.
  • Weakness appears only after about 50% of axons are lost, because of collateral sprouting (Goldman-Cecil Medicine).
• Nerve structure: axon, myelin (made by Schwann cells), endoneurium, perineurium (fascicle) and epineurium.

3. Classification (6 marks)

1. Mononeuropathy: one nerve, e.g. carpal tunnel syndrome or Bell's palsy.
2. Mononeuritis multiplex: several separate nerves, asymmetric and stepwise. Causes are vasculitis, diabetes, leprosy, HNPP and sarcoid.
3. Polyneuropathy: symmetric and length-dependent, with "glove and stocking" loss.
4. Polyradiculoneuropathy: roots and nerves, e.g. GBS and CIDP.
5. Plexopathy and radiculopathy: brachial or lumbosacral plexus, or nerve roots.

• Axonal: the axon degenerates. The cell body is affected in the dying-back pattern.
• Demyelinating: Schwann cell or myelin injury.
• Neuronopathy: DRG or motor neuron loss.
• Mixed patterns occur.

4. Pathophysiology (5 marks)

1. Wallerian degeneration:
   • It follows axonal transection.
   • The distal segment undergoes axonal breakdown, myelin fragmentation and macrophage clearance.
   • Schwann cells proliferate and form bands of Büngner.
   • Regeneration proceeds at about 1 mm/day.
2. Axonal degeneration (dying back): metabolic or toxic injury to the cell body causes distal-first degeneration. The result is a length-dependent pattern.
3. Segmental demyelination:
   • Schwann cell or myelin injury produces slowed conduction and conduction block.
   • Remyelination gives thin myelin and "onion bulbs", which are concentric Schwann cell layers seen in chronic or recurrent disease (CIDP, CMT1).
4. Seddon classification of nerve injury:

5. Clinical approach (6 marks)

• Negative sensory: numbness, "walking on pebbles", loss of temperature sense.
• Positive sensory: paraesthesia, burning pain, allodynia, hyperalgesia.
• Motor: weakness, cramps, fasciculations, foot drop, wasting.
• Autonomic:
  • Postural hypotension and sweating abnormalities.
  • Gastroparesis, bladder and erectile dysfunction.
  • Resting tachycardia.

• Reduced or absent ankle jerks (the earliest sign).
• Stocking sensory loss, with loss of vibration and proprioception.
• Sensory ataxia and a positive Romberg test.
• Distal wasting, foot drop and pes cavus.
• Palpably thickened nerves in leprosy, CMT1 and amyloid.
• Trophic ulcers and Charcot joints in sensory neuropathy.

6. Investigations (5 marks)

1. Nerve conduction studies (NCS) and EMG:
   • Axonal: low amplitudes, relatively preserved velocity.
   • Demyelinating: slow velocity, prolonged distal latency, conduction block, temporal dispersion and prolonged F-waves.
   • EMG shows denervation (fibrillations, positive sharp waves).
   • NCS is normal in pure small-fibre neuropathy, so use skin biopsy (intra-epidermal nerve fibre density) or quantitative sudomotor testing.
2. Blood tests:
   • Glucose, HbA1c and an oral glucose tolerance test.
   • Full blood count and ESR.
   • Renal, liver and thyroid function.
   • B12 (with methylmalonic acid), folate and copper.
   • Serum protein electrophoresis with immunofixation and free light chains.
   • ANA, ANCA and cryoglobulins.
   • HIV, hepatitis B and C, and Lyme serology.
   • Anti-ganglioside antibodies (anti-GQ1b in Miller Fisher syndrome) and onconeural antibodies.
3. CSF: albuminocytologic dissociation (high protein, normal cell count) in GBS and CIDP.
4. Nerve biopsy (sural): used for vasculitis, amyloid, leprosy and sarcoid.
5. Genetic testing: PMP22 duplication or deletion, MPZ, GJB1 and others.
6. Autonomic tests: heart rate variability and tilt table.
7. Imaging: MRI or ultrasound for entrapment and plexopathy.

7. Immune-mediated neuropathies (6 marks)

Guillain-Barré syndrome (GBS)

• Definition: acute inflammatory demyelinating polyradiculoneuropathy (AIDP). It is the commonest cause of acute flaccid paralysis.
• Trigger: an infection 1-3 weeks before onset in about two thirds of patients. Campylobacter jejuni is the commonest trigger and is linked to the axonal AMAN variant. CMV, EBV, Zika, influenza and recent vaccines are other triggers.
• Mechanism: molecular mimicry. Antibodies against gangliosides (GM1, GD1a) cause complement-mediated nerve injury.
• Variants:
  • AIDP (demyelinating).
  • AMAN and AMSAN (axonal).
  • Miller Fisher syndrome (ophthalmoplegia, ataxia, areflexia, anti-GQ1b).
  • Pharyngeal-cervical-brachial variant.
• Clinical features:
  • Ascending symmetric weakness over days, reaching its worst within 4 weeks.
  • Areflexia.
  • Mild sensory symptoms.
  • Back or limb pain.
  • Facial weakness in about 50%.
  • Autonomic instability (arrhythmias, labile blood pressure).
  • Respiratory failure in about 25%.
• Diagnosis: the clinical picture, CSF albuminocytologic dissociation (may be normal in week 1) and NCS (conduction block, prolonged F-waves).
• Management:
  • Admit and monitor vital capacity (FVC), swallowing and the ECG. Intubate if FVC is below 20 mL/kg or falling.
  • Give IVIG 0.4 g/kg/day for 5 days, or plasma exchange (about 5 exchanges over 2 weeks). The two are equally effective, and combining them gives no added benefit. IVIG has efficacy equivalent to plasmapheresis and is easier to manage (Red Book 2021).
  • Steroids do not help.
  • Give DVT prophylaxis, pain control, physiotherapy and nutritional support.
• Prognosis: most recover over months. About 5% die and about 20% are left with significant disability. Poor prognostic factors are age over 60, preceding diarrhoea, the need for ventilation and axonal loss.

CIDP

• Definition: a chronic, relapsing-remitting or progressive immune demyelinating neuropathy lasting more than 8 weeks. Unlike GBS, it follows a chronic course (Robbins Basic Pathology).
• Associations: paraproteinaemia, lymphoid neoplasms, HIV and diabetes.
• Features: symmetric proximal and distal weakness, with sensory loss and areflexia.
• Diagnosis: demyelinating NCS, raised CSF protein and, if needed, a nerve biopsy showing onion bulbs.
• Treatment:
  • Corticosteroids, IVIG or plasma exchange as first line.
  • Steroid-sparing agents such as azathioprine or rituximab if needed.
  • Response to steroids distinguishes it from GBS (Robbins Pathologic Basis of Disease).

Others

• Multifocal motor neuropathy: anti-GM1 antibodies, asymmetric weakness without sensory loss, and conduction block. It responds to IVIG and not to steroids.
• Paraproteinaemic neuropathy: IgM anti-MAG neuropathy.
• Vasculitic neuropathy: mononeuritis multiplex in PAN, EGPA and rheumatoid arthritis. Treat with steroids and cyclophosphamide.

8. Diabetic neuropathy (6 marks)

1. Distal symmetric sensorimotor polyneuropathy: the commonest form. It causes a burning "glove and stocking" sensory loss, which leads to foot ulcers, Charcot arthropathy and amputation.
2. Small-fibre painful neuropathy: burning pain, worse at night.
3. Autonomic neuropathy:
   • Cardiovascular: resting tachycardia and orthostatic hypotension.
   • GI: gastroparesis, diarrhoea and constipation.
   • Genitourinary: neurogenic bladder and erectile dysfunction.
   • Others: sweating abnormalities and hypoglycaemia unawareness.
4. Diabetic amyotrophy (proximal motor neuropathy, Bruns-Garland syndrome): painful asymmetric thigh weakness and wasting. It usually recovers.
5. Mononeuropathies: cranial nerves III and VI (pupil-sparing III), carpal tunnel and ulnar neuropathy.
6. Truncal radiculopathy and treatment-induced neuropathy (after rapid HbA1c reduction).

• Optimise glycaemic control (this is most effective in type 1 diabetes).
• Manage cardiovascular risk factors.
• Give neuropathic pain drugs (section 13).
• Do foot care: annual foot screening with a 10 g monofilament and vibration testing, appropriate footwear and podiatry.
• Treat orthostatic hypotension with fludrocortisone or midodrine.
• Treat gastroparesis with prokinetics.

9. Infective neuropathies (4 marks)

• Leprosy:
  • It is the commonest treatable cause of neuropathy worldwide.
  • It is caused by Mycobacterium leprae, which has a predilection for cooler tissue (skin, superficial nerves).
  • Features include thickened nerves (ulnar, common peroneal, greater auricular), anaesthetic skin patches, and mononeuritis multiplex.
  • Treat with multidrug therapy (dapsone, rifampicin and clofazimine for multibacillary disease) and give steroids for nerve function impairment and reactions.
• Herpes zoster and postherpetic neuralgia: dermatomal vesicular rash with radicular pain. Give antivirals within 72 hours. The vaccine reduces the risk. Treat neuralgia with gabapentinoids, TCAs or a lidocaine patch.
• HIV: distal sensory neuropathy (DSP), antiretroviral toxic neuropathy (stavudine, didanosine), mononeuritis multiplex, CIDP-like and CMV polyradiculopathy.
• Diphtheria: exotoxin-induced demyelination. It causes palatal palsy, then bulbar and limb involvement in the later weeks.
• Lyme disease: Bell's palsy (often bilateral), radiculoneuritis.
• Others: hepatitis B and C (cryoglobulinaemia), and Chagas disease (autonomic).

10. Toxic, nutritional and metabolic neuropathies (5 marks)

11. Hereditary neuropathies (4 marks)

• Clinical features:
  • Onset in the first or second decade.
  • Distal wasting ("inverted champagne bottle" legs).
  • Pes cavus, hammer toes and foot drop.
  • Absent ankle jerks and mild sensory loss.
• Management: there is no cure. Offer physiotherapy, orthoses (AFOs), orthopaedic surgery, genetic counselling, and avoidance of neurotoxic drugs (vincristine).
• Others: hereditary sensory and autonomic neuropathies (HSAN), Fabry disease (small fibre, acroparaesthesia), hereditary transthyretin amyloidosis (treated with tafamidis, patisiran and others), and Refsum disease.

12. Entrapment and cranial neuropathies (5 marks)

13. Management principles (5 marks)

1. Treat the cause: glycaemic control, vitamins, stop toxic drugs, treat infection, and immunotherapy for immune neuropathies.
2. Neuropathic pain drugs: first line is one of the following.
   • Gabapentinoids: gabapentin or pregabalin.
   • SNRIs: duloxetine.
   • TCAs: amitriptyline or nortriptyline.
   • Topical agents: lidocaine 5% patch, capsaicin 8% patch, and capsaicin cream for focal pain.
   • Second line or refractory: tramadol or tapentadol. Avoid strong opioids.
3. Immunotherapy: steroids, IVIG, plasma exchange, rituximab and others as above.
4. Foot care: inspection, footwear, podiatry and prevention of ulcers.
5. Rehabilitation: physiotherapy, occupational therapy, orthoses, falls prevention and fall-risk review.
6. Autonomic support: compression stockings, fludrocortisone, midodrine, and prokinetics.
7. Surgery: for entrapment or nerve transection.

14. Quick differentiation table

Updated evidence note

Ayurvedic Correlation and Management of Neuropathies

1. Basic concept

• Charaka Samhita describes Vata Vyadhi in Chikitsa Sthana ch. 28. It lists the 80 Nanatmaja Vata Vikara in Sutra Sthana ch. 20.
• Sushruta Samhita covers it in Nidana ch. 1.
• Ashtanga Hridaya covers it in Nidana ch. 15.
• Vatarakta is in Charaka Chikitsa ch. 29.

2. Correlation table

3. Nidana (causes)

• Aharaja (diet): Ruksha, Laghu and Sheeta food, Alpa Ashana, Vishamashana, excess Katu, Tikta and Kashaya rasa, and fasting.
• Viharaja (lifestyle): Ativyayama, Ativyavaya, Ratri Jagarana, Vegadharana (suppressing natural urges), Ati Yana (excessive travel) and exposure to cold.
• Manasika: Chinta, Shoka and Bhaya.
• Others: Abhighata (trauma), Dhatukshaya (tissue depletion), Margavarodha (channel obstruction), Madhumeha (diabetes), and Visha and drug toxicity.

4. Samprapti (pathogenesis)

1. Dhatukshaya route: Dhatus (especially Majja, Mamsa and Meda) are depleted. Empty channels (Rikta Srotas) develop Khavaigunya, so aggravated Vata lodges there (Rikta Srotas Vata Prakopa). Features are Shosha (wasting), Ruk, Supti and Kampa. In diabetic neuropathy this is the Apatarpana and depletion type that follows long-standing Madhumeha, with Ojakshaya.
2. Margavarana route: Kapha, Meda or Pitta obstructs the path of Vata (Avarana). Features are Gaurava (heaviness), Supti, Daha and Stambha. This fits Meda-Kapha Avritta Vata in obese diabetic patients.

5. Rupa (clinical features)

• Vata Pradhana: Ruk (pain), Toda (pricking), Stambha (stiffness), Supti (numbness), Kampa (tremor), Shosha (wasting), Sphurana (twitching), Sankocha (contracture) and Spandana.
• Pitta Anubandha: Daha (burning) and Paridaha.
• Kapha Anubandha (Avarana): Gaurava (heaviness) and Shaitya (coldness).
• Complications: Karshya (emaciation) and Vrana (ulcers, for example diabetic foot).

6. Chikitsa Sutra (treatment principles)

1. Nidana Parivarjana: remove the causes. In diabetics, control glycaemia first.
2. Vata Vyadhi basics: Snehana, Swedana, Mridu Samshodhana (Snigdha Virechana), Basti (called Ardha Chikitsa, half of all treatment), Nasya, Abhyanga and Brimhana.
3. If Dhatukshaya is the cause: Brimhana, Santarpana and Rasayana.
4. If Avarana is the cause: remove the obstruction first with Rukshana, Ushna and Shodhana. Then treat the Vata.
5. Madhumeha-related neuropathy: treat both Vata and Prameha. Use Tikta, Katu and Kashaya Dravyas with Snehana in a way that does not worsen Kapha-Meda.
6. Treatment must match Bala (patient strength). Shodhana is only for patients who can tolerate it.

7. Treatment in detail

A. Shodhana and Panchakarma

B. Shamana (oral medicines)

C. Pathya and Apathya

• Pathya: warm, freshly cooked, moderately unctuous food. Old Yava, Mudga, Patola, Karavellaka, Methika, Lasuna, Draksha (with caution in diabetes), Mamsa Rasa where appropriate, and a regular routine.
• Apathya: Ruksha, cold and stale food, fasting, night awakening, excess exercise, suppression of urges, and Navanna, sweets and heavy dairy in diabetics.

D. Yoga and rehabilitation

• Asanas: Tadasana, Pawanmuktasana, Bhujangasana, Vajrasana and Setu Bandhasana (adapt to the patient's capacity).
• Pranayama: Nadi Shodhana and Bhramari.
• Physiotherapy and graded exercise, and foot care. Foot care matters most in diabetic patients.

8. Safety points (important)

1. Heat on insensate limbs: Swedana and warm oil can burn neuropathic skin. Test the temperature on a sensate area.
2. Acute GBS or other emergencies: these need hospital care (ICU monitoring, IVIG or plasma exchange). Panchakarma is for the recovery and rehabilitation phase, not for the acute phase.
3. Rasaushadhi and Bhasma: these may contain heavy metals. Lead, arsenic and mercury themselves cause neuropathy. Use only standardised, tested products from reliable manufacturers.
4. Diabetes: continue glucose monitoring and conventional antidiabetic drugs unless a physician changes them. Herbs such as Gudmar, Vijayasar and Karavellaka can lower glucose further, and hypoglycaemia is a risk.
5. Drug interactions: Guggulu and Ashwagandha can interact with thyroid drugs, sedatives and anticoagulants. Disclose all herbal use to the treating physician.
6. Basti and Virechana need care in weak, elderly or dehydrated patients.
7. Red flags (urgent referral): rapidly progressive weakness, breathing or swallowing difficulty, cauda equina features (saddle numbness, urinary retention), a non-healing foot ulcer, and suspected vasculitis.

9. Evidence status

• The evidence is mainly case reports, small open studies and narrative reviews. A 2026 narrative review ("Ayurveda Therapies in Neurological Disorders") is a general review and not trial evidence.
• My PubMed search for Ayurveda and peripheral nervous system disease found no systematic review or meta-analysis specific to neuropathy.
• Treat Ayurvedic management as complementary to standard care (glycaemic control, immunotherapy, pain drugs and foot care) and not as a replacement. For exams, present the classical concept and the correlation, and state that this is an interpretation by symptoms.

10. Short revision summary

• Neuropathy is not a single Ayurvedic disease, so it is correlated by symptoms with Vata Vyadhi.
• Mechanisms: Dhatukshaya (depletion) and Avarana (obstruction).
• Diabetic neuropathy is an Upadrava of Madhumeha (Vata-Pitta, often with Kapha-Meda Avarana).
• Key correlates: Gridhrasi (sciatica), Avabahuka (brachial and shoulder), Ardita (facial palsy), Khalli and Supti (paraesthesia and numbness), Vatarakta (burning), Pangu and Khanja (weakness and foot drop).
• Treatment: Snehana, Swedana, Basti, Nasya, Abhyanga, oral Guggulu and Kashayam preparations, Pathya and Yoga, while treating the underlying diabetes or other cause.