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Tetanus
Introduction
Tetanus (lockjaw) is an acute neuromuscular disorder caused by the exotoxin tetanospasmin produced by Clostridium tetani, a gram-positive, spore-forming anaerobe ubiquitous in soil and animal intestines. Spores enter via skin breaches (e.g. puncture wounds, burns, umbilical stumps) and germinate in anaerobic conditions. Incubation ranges from 3 to 21 days (mean 8 days), shorter with more severe disease. Generalised tetanus accounts for the majority of cases; neonatal tetanus remains a significant cause of infant mortality in regions with low immunisation coverage. Despite preventive programmes, global mortality remains 10–20% in adults and up to 60% in neonates.
Pathogenesis
- Spores invade devitalised tissue and convert to vegetative bacilli producing tetanospasmin.
- Toxin binds peripheral nerve terminals and is transported retrogradely to the central nervous system.
- Tetanospasmin cleaves synaptobrevin, blocking inhibitory neurotransmitters (glycine, γ-aminobutyric acid) in the spinal cord and brainstem.
- Disinhibition of α-motor neurons and autonomic centres leads to sustained muscle contraction and autonomic instability.
Clinical Manifestations
- Generalised tetanus: trismus, risus sardonicus, neck stiffness, opisthotonus, painful spasms triggered by minimal stimuli; autonomic dysfunction with tachycardia, labile hypertension or hypotension and diaphoresis.
- Cephalic tetanus: following craniofacial wounds; facial nerve palsy, trismus and higher mortality.
- Localised tetanus: spasms confined to muscles near the wound; may progress to generalised disease.
- Neonatal tetanus: onset 3–14 days after birth; poor feeding, irritability, trismus and generalized rigidity; high fatality without intensive care.
Diagnosis
Clinical diagnosis is based on characteristic muscle rigidity and spasms in the absence of alternative causes. Confirmation by toxin detection is rarely available and treatment should not be delayed for laboratory results.
Ablett Classification of Severity
| Grade | Features |
|---|---|
| 1 (Mild) | Mild trismus, minimal spasms, no respiratory or autonomic compromise |
| 2 (Moderate) | Moderate trismus and spasms, mild dysphagia, tachypnoea (RR >30 min⁻¹), no apnoea |
| 3 (Severe) | Prolonged spasms, severe dysphagia, apnoeic episodes, pulse >120 min⁻¹ |
| 4 (Very severe) | Grade 3 plus marked autonomic dysfunction (labile BP, arrhythmias) |
Differential Diagnosis
Hypocalcaemia, strychnine poisoning, dystonic reactions, epileptic seizure, meningoencephalitis, rabies, severe tetanus-like syndromes (e.g. neonatal botulism).
Management
Neutralise Unbound Toxin
| Intervention | Dose / Notes |
|---|---|
| Human tetanus immune globulin (TIG) | 3 000–6 000 IU IM in a single dose (give IVIG 150–300 mg kg⁻¹ if TIG unavailable). Inject at a site remote from toxoid. |
| Intrathecal TIG | 500 IU via lumbar puncture in addition to IM dose–may shorten ICU stay (limited RCT data). |
Eradicate the Source
- Prompt surgical debridement ± removal of foreign material.
- Metronidazole 500 mg IV 6-hourly for 7–10 days (superior or equivalent to penicillin and avoids theoretical GABA antagonism).
- Penicillin G (4 MU IV 4-hourly) acceptable alternative if metronidazole contraindicated.
Control Muscle Rigidity & Spasm
| Modality | Practical guidance |
|---|---|
| Benzodiazepines | Diazepam 0.2–1 mg kg⁻¹ h⁻¹ (NG or IV); Midazolam infusion for titratable sedation. |
| Propofol | Useful adjunct for burst suppression during refractory spasms. |
| Magnesium sulfate | Load 40–50 mg kg⁻¹ (max 5 g) over 30 min → infuse 2–3 g h⁻¹; target serum 2–4 mmol L⁻¹. Reduces sedative/NMBA needs and autonomic storms. Monitor deep-tendon reflexes & MAP. |
| Neuromuscular blockade | Vecuronium or rocuronium for ventilated patients. Avoid suxamethonium (hyperkalaemia risk). |
| Intrathecal baclofen | Consider for refractory spasms (bolus 300–500 μg then 500–2 000 μg day⁻¹); growing 2023–25 evidence of reduced ventilation time. |
| Dantrolene | 1–2 mg kg⁻¹ IV bolus then 1–2 mg kg⁻¹ 6-hourly; limited data. |
Manage Autonomic Dysfunction
| Agent | Typical regimen | Comment |
|---|---|---|
| Magnesium sulfate | As above | First-line; blunts catecholamine release & receptor responsiveness. |
| Clonidine | 0.5–2 μg kg⁻¹ h⁻¹ IV | α₂-agonist; diminishes sympathetic tone. |
| Dexmedetomidine | 0.2–0.7 μg kg⁻¹ h⁻¹ IV | Case-series support for severe dysautonomia with fewer hypotensive episodes than clonidine. |
| Labetalol infusion | 0.25–1 mg min⁻¹ | Combined α/β blockade; avoid long-acting β-blockers. |
| High-dose atropine | For dominant vagal episodes (bradycardia/asystole). |
Supportive Critical Care
- Admit Grade ≥ 2 to ICU; early elective tracheostomy preferred to avoid repeated airway stimulation.
- Lung-protective ventilation; frequent gentle suctioning.
- Caloric requirement 40–50 kcal kg⁻¹ day⁻¹ (high-protein enteral feeds).
- Deep sedation, minimal environmental stimuli (dark room, ear-plugs).
- VTE prophylaxis, stress-ulcer & pressure-area care, active normothermia.
- Daily serum Mg²⁺, Ca²⁺, renal profile; continuous invasive BP & ECG.
Immunisation
- Disease does not confer immunity–commence full course with adsorbed tetanus-diphtheria (Td) vaccine (0, 4–6 weeks, 6 months) on admission, in a separate limb from TIG.
Anaesthetic Considerations
- Airway–anticipate difficult mouth opening, secretion load and risk of reflex spasms; avoid unnecessary stimulation; gentle awake fibre-optic or tracheostomy under deep sedation preferred for definitive airway.
- Induction & maintenance–volatile (sevoflurane) ± propofol with generous opioids; avoid ketamine (sympathomimetic). Maintain deep anaesthesia before any surgical or endoscopic stimulus.
- Muscle relaxants–non-depolarisers; monitor neuromuscular function carefully in presence of magnesium.
- Autonomic storms intra-operatively–have magnesium, esmolol, nitroprusside, dexmedetomidine ready.
- Post-operative care–ICU ventilatory support until spasms and autonomic lability fully controlled.
Prognosis & Predictors of Mortality
- Overall mortality 5–50 % depending on ICU resources.
- Poor prognostic factors: ablett Grade 3–4, incubation < 7 days, onset period < 48 h, age > 60 yrs, uncontrolled autonomic dysfunction, delayed TIG administration.
Links
Polytrauma and haemorrhagic shock
References:
- Taylor, A. M. (2006). Tetanus. Continuing Education in Anaesthesia Critical Care &Amp; Pain, 6(3), 101-104. https://doi.org/10.1093/bjaceaccp/mkl014
- Sudarshan R, et al. Tetanus: recognition and management. Lancet Infect Dis. 2025.
- Karnad DR, Gupta V. Intensive care management of severe tetanus. Indian J Crit Care Med. 2021;25(S2):S155–S160.
- Aiello M, et al. Prolonged administration of intrathecal baclofen in generalized grade 4 tetanus. Reg Anesth Pain Med. 2024;49:540–2.
- Thwaites CL, et al. Magnesium sulphate for treatment of severe tetanus: randomised controlled trial. Lancet. 2006;368:1436–43.
- World Health Organization. Tetanus fact sheet. WHO; 2023.
- Up-to-date. Tetanus. Wolters Kluwer; 2025 (accessed Jun 2025).
- Medscape Drugs & Diseases. Tetanus–treatment & management. Updated 2025.
- Mahajan R, Kumar A, Singh SK. General anesthesia in tetanus patient undergoing emergency surgery: A challenge for anesthesiologist. Anesth Essays Res. 2014 Jan-Apr;8(1):96-8. doi: 10.4103/0259-1162.128922. PMID: 25886114; PMCID: PMC4173597.
- The Calgary Guide to Understanding Disease. (2024). Retrieved June 5, 2024, from https://calgaryguide.ucalgary.ca/
- FRCA Mind Maps. (2024). Retrieved June 5, 2024, from https://www.frcamindmaps.org/
- Anesthesia Considerations. (2024). Retrieved June 5, 2024, from https://www.anesthesiaconsiderations.com/
Summaries
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© 2025 Francois Uys. All Rights Reserved.
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