Life-threatening neurologic illness caused by *Clostridium tetani* exotoxin (tetanospasmin), characterized by muscle rigidity and intense spasms (classically beginning with lockjaw).
Despite being vaccine-preventable, tetanus still causes fatalities in under-immunized patients and resource-poor regions. Early recognition is critical for timely treatment (airway support, antitoxin) and is a classic exam scenario highlighting wound management and immunization status.
Trismus (lockjaw) is usually the first symptom, along with neck stiffness and dysphagia, appearing about a week after an injury. The muscle rigidity then generalizes downward, causing board-like abdominal wall and limb stiffness.
Facial muscle contraction produces a forced grin (risus sardonicus) and severe extensor spasms can lead to opisthotonus (exaggerated arching of the back) in advanced cases.
Spasms are extremely painful and often triggered by minor stimuli (e.g. light, noise, touch). Importantly, patients remain conscious and have no sensory deficits during these episodes (tetanus affects motor neurons, not sensory).
Suspect tetanus in any patient with a recent wound and new-onset jaw stiffness or muscle spasms – especially if they have not been fully vaccinated. Diagnosis is clinical (no rapid lab test), so begin treatment promptly rather than waiting for cultures.
Management requires addressing four priorities: remove the source (aggressive wound debridement + antibiotics), neutralize the toxin (give antitoxin TIG), control muscle spasms (benzodiazepines as first-line), and support vital functions (airway protection, quiet environment).
Condition
Distinguishing Feature
Strychnine poisoning
Similar convulsive muscle spasms but lacks the autonomic dysfunction of tetanus; usually from ingesting rodent poison or tainted drugs.
Acute dystonic reaction
Drug-induced muscle contractions (e.g. neck/jaw dystonia from antipsychotics) can mimic lockjaw, but occurs in context of medication use and without a wound or generalized spasms.
Hypocalcemic tetany
Muscle cramps/tetany from low calcium can cause carpal spasms and paresthesias, but not the severe sustained contractions or autonomic instability seen in tetanus.
Wound care + antibiotics: Thoroughly debride the wound and give antibiotics (first-line metronidazole) to eradicate *C. tetani* and halt toxin production.
Neutralize toxin: Administer human tetanus immune globulin (TIG) as soon as possible to bind unbound toxin. Also give tetanus toxoid vaccine (active immunization) once the patient is stable, because tetanus infection does not confer lasting immunity.
Supportive care: Control muscle spasms with benzodiazepines (e.g. IV diazepam) and minimize external stimuli (quiet, dark environment). Monitor in ICU; be prepared for airway support (intubation) if laryngospasm or respiratory failure threatens.
Tetanus vs botulism: Tetanus toxin blocks inhibitory neurons (GABA/glycine) causing spastic paralysis, whereas botulinum toxin blocks ACh release causing flaccid paralysis. Think "tetanic = tense" and "botulism = limp."
Know the abbreviations: TIG = Tetanus Immune Globulin (passive antibodies to neutralize toxin). TT/Td/Tdap = tetanus toxoid vaccines (active immunity; *Tdap* includes pertussis) given for routine immunization and boosters.
Autonomic instability (labile blood pressure, arrhythmias, high fever, profuse sweating) indicates severe tetanus and a high risk of complications. Intensive care and aggressive management are required.
Respiratory compromise from laryngospasm or chest wall rigidity is the leading cause of death in tetanus. Early intubation and mechanical ventilation can be life-saving if there are signs of airway obstruction or apnea.
Clean the wound thoroughly (debridement) + start metronidazole
TIG IM (passive antitoxin) + Tetanus toxoid vaccine (active immunization)
Sedation & airway: Give benzodiazepines for spasms; intubate if needed; ICU supportive care
Unvaccinated adult with a puncture wound (rusty nail) 5–10 days ago, now presenting with lockjaw, painful muscle spasms (often induced by loud sounds or touch), and an arched back posture (opisthotonus) → Tetanus.
Newborn (1 week old) born via an unsanitary delivery who develops inability to breastfeed, trismus, and body rigidity a few days after birth → Neonatal tetanus (infection of the umbilical stump).
Case 1
A 52‑year‑old man with no recent immunizations stepped on a rusty nail 7 days ago. He now reports stiffness of the jaw and neck, difficulty swallowing, and episodes of severe muscle spasms triggered by loud noises. During these episodes he has a grimacing smile and his back arches rigidly, though he remains alert.
Microscopic illustration of Clostridium tetani (bacteria with characteristic drumstick spore at one end).
