Tetanus
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Direct answer
Trismus in a clear-minded child two weeks after a puncture wound is tetanus: tetanospasmin, carried intra-axonally to the central nervous system, blocks glycine and GABA inhibition, so every stimulus explodes into spasm — risus sardonicus, opisthotonus, laryngeal contraction — while consciousness and cerebrospinal fluid stay normal. Management is human tetanus immunoglobulin for unbound toxin, wound toilet, metronidazole, and diazepam or magnesium for the spasms in a dark, quiet room. Neonatal tetanus — stiffness and spasms after day 3 of life from an unclean cord — is the vaccine-preventable form India validated as eliminated in 2015.
What you must remember
- Incubation 3–21 days, commonly about ten; the shorter the incubation and the shorter the trismus-to-first-spasm interval, the worse the prognosis.
- The sequence: trismus first, then risus sardonicus, then opisthotonus and reflex spasms triggered by noise, light or touch; between spasms there is rigidity, and the sensorium stays intact — the sign that separates tetanus from its mimics.
- The spatula test: touching the posterior pharynx provokes masseter spasm and biting instead of gagging; autonomic instability with labile pressure marks severe disease.
- Portals in children: puncture wounds, burns, compound fractures, ear piercing, chronic otitis media (otogenic tetanus), unsterile injections, and the neonatal umbilical stump contaminated by traditional applications.
- Treatment package: human tetanus immunoglobulin — commonly 3000–6000 IU intramuscularly or intravenously per severity, some infiltrated around the wound — debridement, metronidazole (preferred to penicillin, a GABA antagonist that can worsen spasms), diazepam or midazolam for spasms, magnesium for autonomic storms, and paralysis with ventilation if refractory.
- Nursing is therapy: dark quiet room, clustered minimal handling, nasogastric feeding, and tracheostomy readiness.
- Recovery takes weeks because bound toxin cannot be dislodged — and survival confers no immunity, so active immunisation begins during convalescence.
- Neonatal tetanus presents at 3–28 days (commonly 5–14) with inability to suck, then stiffness and spasms, in a baby of an unimmunised mother with an uncleanly managed cord; prevention is TT/Td in pregnancy and the six cleans of safe delivery.
- Wound prophylaxis: a tetanus-prone wound (deep, devitalised, soil- or faecal-contaminated, penetrating, burns, over six hours old) in an incompletely immunised child gets both TT and 250–500 IU of TIG.
Working through the wound-prophylaxis table
A nine-year-old arrives with a soil-contaminated nail puncture six hours old; his card shows three DTP doses in infancy and boosters to 18 months. This is a tetanus-prone wound in a child whose immunisation is incomplete: the prescription is a Td booster now plus human TIG 250 IU intramuscularly at a separate site, with wound toilet and schedule completion. The exam's three scenarios: the fully immunised child with a clean wound needs nothing, or a booster beyond ten years; the fully immunised child with a tetanus-prone wound needs an early booster; the incompletely or unknown-immunised child with anything but the cleanest wound gets booster plus immunoglobulin. Two details make the table memorable: immunoglobulin is never given in the same syringe or site as the vaccine, and five childhood doses are the shield that lets most wounds be managed with a booster alone. Had this child returned instead with trismus three weeks later, the pathway jumps to treatment — TIG, metronidazole, debridement, diazepam titrated to spasms, and a dark room.
Where students slip
Consciousness: a "convulsing" child who is awake and terrified between spasms has tetanus, and a lumbar puncture is both unnecessary and a stimulus that triggers a spasm. Penicillin is still written by habit; metronidazole is preferred for the reason above. The trismus gets blamed on a dental cause — peritonsillar abscess brings high fever, drooling, a muffled voice and toxicity, not intermittent spasms. And the neonate who stopped feeding on day 7 of an unclean cord is "just a poor feeder" until the stiffness declares itself; the exam's version of the mistake asks for the single most effective prevention — maternal TT in pregnancy.
Frequently asked questions
What is the classic sequence of tetanus signs?
Trismus first, then risus sardonicus, opisthotonus and stimulus-triggered reflex spasms, with consciousness preserved and the cerebrospinal fluid normal.
Why is metronidazole preferred over penicillin?
Penicillin is a GABA antagonist and can theoretically aggravate spasms; metronidazole covers Clostridium tetani equally without that effect.
How is neonatal tetanus recognised?
A baby aged 3–28 days, born to an unimmunised mother with an unclean cord, who first stops suckling, then stiffens and spasms — diagnosed by history and examination alone.
When is TIG given for wound prophylaxis?
With tetanus-prone wounds in children whose immunisation is incomplete or unknown — 250–500 IU intramuscularly alongside the TT booster, never in the same syringe or site.
Does recovery from tetanus confer immunity?
No — the toxin dose causing disease is too small to immunise, so active vaccination with TT/Td starts during convalescence.
What is the role of diazepam and magnesium?
Diazepam or midazolam controls and sedates spasms; intravenous magnesium stabilises autonomic storms; refractory cases need neuromuscular paralysis with ventilation.