Tetanus
Summary
Tetanus is a severe, potentially fatal neurological disease caused by the exotoxin Tetanospasmin produced by the anaerobic bacterium Clostridium tetani. The spores of C. tetani are ubiquitous in soil and enter the body through wounds. The toxin blocks the release of inhibitory neurotransmitters (GABA and Glycine) at the spinal cord and brainstem, causing unopposed motor neuron excitation, resulting in sustained muscle spasm (spastic/rigid paralysis). Classic features include Trismus (Lockjaw), Risus Sardonicus, Opisthotonus, and generalised muscle spasms. Severe cases involve autonomic dysfunction and respiratory failure. Tetanus is preventable by vaccination (DTaP/Td/Tdap). Treatment involves Human Tetanus Immunoglobulin (HTIG) to neutralise circulating toxin, Metronidazole to kill the organism, wound debridement, sedation/muscle relaxation (Benzodiazepines, Magnesium), and ICU support. Mortality remains 10-20% even with modern intensive care. [1,2]
Clinical Pearls
Tetanus is Preventable, Not Curable: Once toxin binds to neurons, it cannot be removed. Recovery requires new nerve terminal growth (weeks). Prevention through vaccination is key.
"Spatula Test" (Highly Specific): Touching the posterior pharynx with a spatula causes jaw spasm (bite the spatula) instead of a gag reflex. Sensitivity 94%, Specificity 100%.
Rusty Nail is a Myth: Any wound can cause tetanus. Clean wounds can too if immunity is inadequate. Always check vaccination status.
Autonomic Dysfunction Kills: Beyond spasms, catecholamine storms cause arrhythmias and sudden death. Magnesium and careful sedation are crucial.
Global Burden
- Rare in Developed Countries: UK sees less than 10 cases/year (high vaccination coverage).
- Endemic in Developing Countries: ~38,000 deaths/year globally (primarily neonatal tetanus from unclean umbilical cord practices).
- Mortality: 10-20% with ICU care; up to 50% without.
Risk Factors
| Factor | Notes |
|---|---|
| Inadequate Vaccination | 3-dose primary course not completed; no booster >10 years. |
| Wound Contamination | Soil, Manure, Rusty metal (myth focuses on rust, but any dirty wound is risky). |
| Puncture Wounds / Deep Wounds | Anaerobic environment favours C. tetani growth. |
| Injection Drug Use (IVDU) | Contaminated needles. |
| Burns / Crush Injuries | Tissue necrosis creates anaerobic environment. |
| Neonatal Tetanus | Umbilical stump infection (unsterile cord cutting). |
| Elderly | Waning immunity with age. |
Mechanism of Tetanospasmin
- Entry: Clostridium tetani spores enter through wound (even minor).
- Germination: Anaerobic wound conditions allow spores to germinate and vegetative bacteria to grow.
- Toxin Production: Bacteria produce Tetanospasmin (Tetanus Toxin – one of the most potent toxins known).
- Retrograde Axonal Transport: Toxin binds peripheral nerve terminals and travels retrogradely up the axon to the spinal cord and brainstem.
- Binding to Inhibitory Interneurons: Toxin irreversibly binds to presynaptic terminals of inhibitory neurons (Renshaw cells, GABAergic/Glycinergic interneurons).
- Blocks Neurotransmitter Release: Cleaves SNARE proteins (VAMP/Synaptobrevin), preventing release of GABA and Glycine.
- Disinhibition: Loss of inhibitory control on alpha motor neurons → Unopposed excitation → Sustained muscle contraction (Spasm).
- Autonomic Dysfunction: Toxin also affects autonomic neurons → Catecholamine surges, Labile BP, Tachyarrhythmias.
- Recovery: Requires growth of new nerve terminals (weeks to months).
Types of Tetanus
| Type | Description |
|---|---|
| Generalised | Most common (80%). Affects whole body. Starts with trismus, descends. |
| Localised | Rigidity confined to muscles near wound. May progress to generalised. |
| Cephalic | Rare. Follows head/facial wounds. CN palsies (especially VII) + Trismus. |
| Neonatal | Umbilical stump infection. "Floppy baby" → Rigidity → Spasms. High mortality. |
| Condition | Key Features |
|---|---|
| Tetanus | Wound history. Trismus, Risus Sardonicus, Opisthotonus. Spasms triggered by stimuli. Positive Spatula Test. Normal consciousness. |
| Rabies | Animal bite. Hydrophobia, Aerophobia (not trismus). Encephalopathy. |
| Strychnine Poisoning | Rat poison ingestion. Similar spasms. No trismus. Rapid onset. History of ingestion. |
| Dystonic Reaction (Drug-Induced) | Antipsychotic/Antiemetic use. Oculogyric crisis. Responds to Anticholinergics (Procyclidine). |
| Meningitis / Encephalitis | Neck stiffness (not trismus). Fever, Photophobia. Altered consciousness. |
| Dental Abscess / TMJ Disorder | Trismus only. No generalised spasms. Localised oral/jaw pathology. |
| Hypocalcaemia | Tetany (Trousseau's, Chvostek's). Carpopedal spasm. Low Calcium. |
| Stiff Person Syndrome | Chronic. Antibodies (Anti-GAD). No wound. Slow progression. |
Incubation Period
Classic Clinical Features
Trismus (Lockjaw)
Risus Sardonicus
Opisthotonus
Generalised Muscle Rigidity
Reflex Spasms
Autonomic Dysfunction (Severe Cases)
Spatula Test (Bedside Diagnostic Test)
Clinical Diagnosis
- Tetanus is a clinical diagnosis. No confirmatory lab test.
Laboratory (Supportive, Rule Out Differentials)
| Test | Notes |
|---|---|
| FBC, U&E, CRP | Non-specific. May have leucocytosis. |
| Calcium | To exclude hypocalcaemic tetany. |
| Creatine Kinase (CK) | Often elevated (muscle damage from spasms). |
| Wound Culture | C. tetani rarely isolated. Not useful for diagnosis. |
| CSF (If LP Done) | Normal (unlike meningitis). |
Severity Scoring (Ablett Classification)
| Grade | Features |
|---|---|
| I (Mild) | Mild trismus, General rigidity, No spasms, No dysphagia, No respiratory distress. |
| II (Moderate) | Moderate trismus, Rigidity, Mild-moderate spasms, Mild dysphagia, Mild respiratory distress. |
| III (Severe) | Severe trismus, Severe rigidity, Severe spasms, Severe dysphagia, Respiratory distress, Tachycardia >120. |
| IV (Very Severe) | Grade III + Autonomic dysfunction (Severe cardiovascular instability). |
Management Algorithm
SUSPECTED TETANUS
(Trismus, Rigidity, Spasms + Wound History)
↓
IMMEDIATE RESUSCITATION (ABCDE)
- Protect Airway (Consider early intubation if laryngospasm risk)
- High-flow Oxygen
- IV Access
- Cardiac Monitoring
- Quiet, Dark Room (Reduce stimulation)
↓
NEUTRALISE CIRCULATING TOXIN
┌──────────────────────────────────────┐
│ HUMAN TETANUS IMMUNOGLOBULIN (HTIG) │
│ - 3000-6000 IU IM (Single dose) │
│ - Give EARLY (Cannot remove bound │
│ toxin, only neutralises free) │
│ - +/- Intrathecal HTIG (debated) │
└──────────────────────────────────────┘
↓
STOP TOXIN PRODUCTION
┌──────────────────────────────────────┐
│ ANTIBIOTICS │
│ - Metronidazole 500mg IV/PO TDS │
│ x 7-10 days (First-line) │
│ - (Avoid Penicillin – GABA antagonist)│
│ │
│ WOUND DEBRIDEMENT │
│ - Surgical debridement of wound │
│ - Remove necrotic tissue / foreign │
│ body │
└──────────────────────────────────────┘
↓
CONTROL SPASMS
┌──────────────────────────────────────┐
│ BENZODIAZEPINES (First-line) │
│ - Diazepam 10-40mg IV (Titrated) │
│ - Or Midazolam Infusion (ICU) │
│ │
│ MAGNESIUM SULPHATE │
│ - 2-4g IV loading then 1-3g/hr │
│ - Reduces spasms + Autonomic dysf. │
│ │
│ NEUROMUSCULAR BLOCKADE (If needed) │
│ - Vecuronium / Rocuronium │
│ - Requires intubation + ventilation │
│ │
│ BACLOFEN (Intrathecal - Specialist) │
└──────────────────────────────────────┘
↓
MANAGE AUTONOMIC DYSFUNCTION
┌──────────────────────────────────────┐
│ - Magnesium (Also helps autonomic) │
│ - Labetalol / Esmolol (Beta-block) │
│ - Clonidine / Dexmedetomidine │
│ - Morphine (Carefully) │
│ - Avoid sudden interventions │
└──────────────────────────────────────┘
↓
ICU CARE
- Prolonged ventilation (weeks)
- Tracheostomy often required
- Nutrition (NG/PEG)
- DVT Prophylaxis
- Physiotherapy
↓
BEFORE DISCHARGE:
- VACCINATE (Tetanus does NOT confer natural immunity)
- Complete primary course if incomplete
Human Tetanus Immunoglobulin (HTIG)
- Dose: 3000-6000 IU IM (Single dose). Some give 500 IU around wound.
- Purpose: Neutralises circulating (unbound) toxin. Does NOT remove toxin already bound to neurons.
- Timing: Give as early as possible.
Antibiotics
- Metronidazole 500mg IV/PO TDS for 7-10 days (First-line).
- Avoid Penicillin (Theoretical GABA antagonism may worsen spasms).
Spasm Control
| Agent | Notes |
|---|---|
| Benzodiazepines | First-line. Diazepam or Midazolam. High doses often needed. GABA agonist. |
| Magnesium Sulphate | Reduces spasms and autonomic instability. Monitor Mg levels. |
| Neuromuscular Blockade | Vecuronium/Rocuronium if above fails. Requires intubation and ventilation. |
| Baclofen (Intrathecal) | Specialist use. GABA-B agonist. |
UK Vaccination Schedule
| Dose | Age | Notes |
|---|---|---|
| 1st | 8 weeks | DTaP/IPV/Hib/HepB (6-in-1) |
| 2nd | 12 weeks | DTaP/IPV/Hib/HepB |
| 3rd | 16 weeks | DTaP/IPV/Hib/HepB |
| Booster 1 | 3 years 4 months | dTaP/IPV (Preschool Booster) |
| Booster 2 | 14 years | Td/IPV (School Leaver Booster) |
- 5 doses = Lifelong immunity in most people.
Wound Management (PHE Guidelines)
| Wound Type | Vaccination History | Action |
|---|---|---|
| Clean, Minor | Up-to-date (5 doses) | None |
| Clean, Minor | Incomplete / Unknown | Give Td vaccine |
| Tetanus-Prone (Dirty, Puncture, Contaminated) | Up-to-date | None |
| Tetanus-Prone | 3+ doses, >10 years since last | Td vaccine |
| Tetanus-Prone | less than 3 doses or Unknown | Td vaccine + HTIG |
| Complication | Notes |
|---|---|
| Respiratory Failure | Laryngospasm, Diaphragm spasm. Requires intubation/ventilation. |
| Aspiration Pneumonia | From dysphagia/spasm. |
| Autonomic Dysfunction | Arrhythmias, Labile BP, Sudden Death. |
| Fractures | From severe spasms (Vertebral fractures, Long bone fractures). |
| Tendon Ruptures | Especially Achilles. |
| Pressure Injuries | Prolonged ICU stay. |
| DVT/PE | Immobility. Prophylaxis essential. |
| Nosocomial Infections | VAP, Catheter infections. |
- Mortality: 10-20% with modern ICU care. Higher in extremes of age, short incubation, severe autonomic dysfunction.
- Recovery: Slow (weeks to months). Bound toxin cannot be removed; new nerve terminals must grow.
- No Natural Immunity: Tetanus does NOT confer immunity. Patients MUST be vaccinated before discharge.
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| Tetanus PEP | PHE (UKHSA) | Wound assessment, HTIG + Vaccine indications. |
| Tetanus Management | WHO | HTIG, Metronidazole, Benzodiazepines, Magnesium. |
What is Tetanus?
Tetanus is an infection caused by a germ called Clostridium tetani, which lives in soil. If it gets into a wound, it produces a poison (toxin) that affects your nerves, causing severe muscle stiffness and spasms, including "lockjaw".
Is it serious?
Yes. Tetanus can be life-threatening. The muscle spasms can affect your breathing and heart. However, it is very rare in the UK because most people are vaccinated.
How is it prevented?
Vaccination. The tetanus vaccine is part of the routine childhood immunisation schedule. Adults may need a booster if they have a dirty wound and haven't had a vaccine in over 10 years.
How is it treated?
Treatment involves medication to neutralise the toxin, antibiotics to kill the bacteria, and drugs to control the muscle spasms. Many patients need intensive care for several weeks.
Primary Sources
- PHE (UKHSA). Tetanus: The Green Book, Chapter 30. 2022.
- World Health Organization. Current recommendations for treatment of tetanus during humanitarian emergencies. WHO Technical Note. 2010.
Common Exam Questions
- Classic Triad: "What are the classic clinical features of Tetanus?"
- Answer: Trismus (Lockjaw), Risus Sardonicus, Opisthotonus.
- Mechanism of Toxin: "How does Tetanospasmin cause spasms?"
- Answer: Blocks release of inhibitory neurotransmitters (GABA, Glycine) at spinal cord → Unopposed motor neuron excitation → Spastic paralysis.
- Spatula Test: "What is the Spatula Test?"
- Answer: Touching posterior pharynx causes jaw spasm (biting spatula) instead of gag reflex. Highly specific for tetanus.
- Antibiotic Choice: "Why is Metronidazole preferred over Penicillin?"
- Answer: Penicillin is a GABA antagonist and may theoretically worsen spasms.
Viva Points
- Vaccination After Tetanus: Emphasise that tetanus does NOT confer natural immunity – patient MUST be vaccinated before discharge.
- Autonomic Dysfunction: Explain that this is a major cause of death in those who survive the spasm phase.
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.