✅ Autonomic Neuropathy (AN) – dysfunction of the autonomic nervous system (ANS) due to damage of sympathetic, parasympathetic, or enteric fibres. It affects blood pressure, heart rate, GI motility, bladder control, sweating, and sexual function. 👉 Always search for treatable causes – e.g., diabetes, drug effects, systemic disease.

🔎 Causes

Metabolic/Systemic: Diabetes mellitus (up to 30% of long-standing diabetics), uraemia, porphyria.
Neurological: CIDP, Guillain–Barré, amyloidosis, HIV, HSAN (hereditary sensory + autonomic neuropathies).
Medications: Diuretics, antihypertensives, insulin, levodopa, dopamine agonists.
Toxins: Alcohol, chemotherapy agents, opiates.
Situational: Postprandial hypotension, vasovagal syncope, volume depletion.

💥 Clinical Effects

Cardiovascular: Orthostatic hypotension (↓SBP ≥20 mmHg or ↓DBP ≥10 mmHg in 3 min), resting tachycardia, silent ischaemia.
Gastrointestinal: Gastroparesis, constipation/diarrhoea, reflux, faecal incontinence.
Urogenital: Bladder dysfunction, erectile dysfunction (male), reduced libido (female), retrograde ejaculation.
Sudomotor: Anhidrosis or hyperhidrosis, impaired thermoregulation.

🩺 Clinical Assessment

Exclude hypovolaemia or acute illness.
Screen for neurodegenerative disorders (PD, MSA, LBD).
Look for systemic symptoms (weight loss, fever, night sweats) suggesting malignancy or amyloidosis.

📊 Investigations

Bloods: U&E, FBC, HbA1c, glucose, CRP, CK, TFTs, cortisol (if Addison’s suspected).
Imaging: CXR/AXR for GI evaluation.
Autonomic Function Tests: HR variability (deep breathing), Valsalva, tilt-table test, thermoregulatory sweat test / QSART.
Cardiac: ECG, 24h Holter, echocardiography.

💊 Management

Address underlying cause: optimise diabetes, withdraw offending drugs, treat systemic disease.
Non-pharmacological (first-line for orthostatic hypotension): Hydration, salt intake, compression stockings, gradual position changes.
Pharmacological:
- Fludrocortisone → expands plasma volume.
- Midodrine (α1 agonist) → raises BP by vasoconstriction.
- Pyridostigmine → reserved for resistant cases.
Symptom-specific treatment:
- Gastroparesis → metoclopramide, domperidone.
- Diabetic diarrhoea → loperamide, clonidine.
- Erectile dysfunction → PDE-5 inhibitors.
- Bladder dysfunction → timed voiding, intermittent catheterisation if retention.

📉 Prognosis

Autonomic neuropathy is a marker of advanced systemic disease (esp. diabetes) and associated with ↑ mortality. Early recognition & management improve quality of life.

📚 References & Guidelines

💡 Exam Pearls

• Think diabetes when orthostatic hypotension + gastroparesis + ED. • Always exclude hypovolaemia before diagnosing AN. • Midodrine & fludrocortisone are key drugs; lifestyle measures remain first-line.

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Autonomic neuropathy ✅