151. Tetanus

General

Uncommon in the US; mostly in California, Texas, Florida (very low prevalence in high altitudes) in older patients with inadequate immunity. 11% mortality, more likely in the elderly.

Most cases related to acute wound or puncture wound; did not seek medical care or did not receive tetanus when seeking care.

Clostridium tetani, gram positive anaerobic rod. Creates indestructible spores that germinate into its toxin-producing form. Two toxins: tetanolysin which increases bacteria production and tetanospasmin, which is the neurotoxin.

Prevents release of glycine and GABA from presynaptic nerve terminals. Loss of inhibition. No person-to-person transmission.

Features

Muscular rigidity, muscular contractions, increased sympathetic system. Incubation period is 1 day to 1 month. Looks like strychnine poisoning. Other considerations: dystonic reaction, hypocalcemia, malignant neuroleptic syndrome, serotonin syndrome, rabies.

Generalized tetanus: 80% of pts. Initially present with lock jaw (masseter muscles). Descends to neck, chest, extremities. Risus sardonicus (sardonic smile/grin). Tonic muscle contractions and convulsive spasms occur. Opisthotonus – body bent concave forward, resting on head and heels. Extension of lower extremities. No change in mental status though. Conscious until contraction of respiratory muscles. After first week, more sympathetic response occurs with tachycardia, elevated BP, sweating, increased urination. Can last for months before nerve regrow. Complications: rhabdo, long-bone fractures. Aspiration pneumonia found in 50-70% of autopsies.

Neonatal tetanus: Due to unsterile treatment of umbilical stump, poorly immunized mother. Usually occurs in second week of life. Weak, irritable, unable to suck.

Cephalic tetanus: Usually related to facial injuries and involves cranial nerves. Usually seventh (facial) nerve involved.

Local tetanus: Just localized tetanus near wound; can progress to generalized.

Testing

Clinical diagnosis. Not really a good test. Wound cultures can grow the bug, but doesn’t mean you have tetanus. Serum antitoxin titers > 0.1 are protective, though there have been cases with normal levels. Consider checking urine strychnine to rule out strychnine poisoning.

Treatment

Usually ICU admission for respiratory monitoring. If intubated, may need to do neuromuscular blockade.

Human tetanus immunoglobulin (TIG) knocks out the circulating toxin, though does not neutralize the toxin already in the nerves. Helps reduce mortality. 3000-6000 units IM with some injected into wound. Do this before cleaning the wound bc toxin can be released during handling.

Antibiotics: Metronidazole usually given, but doesn’t really help. Don’t give PCN (centrally acting GABA antagonist).

Muscle relaxation: Usually benzos, though only give water-soluble midazolum (versed) due to propylene glycol solution in lorazepam or diazepam.

Magnesium sulfate can help reduce sympathetic. Labetolol probably preferred B-blocker due to both alpha/beta activity. Consider morphine or clonidine as well.

Immunization

When diagnosed with tetanus, should receive tetanus toxoid IM at presentation, then at 6 weeks and 6 months. Disease dose not create immunity.

TdaP (Tetanus-diptheria-acellular pertussis / Adacel) booster every 10 years in adults > 19yo. Td vaccination is 3-shot series starting at 2 months.

Wound Management: If unsure of previous 3-dose series, give TIG. If minor wound with low contamination, booster given if last booster was > 10 years. If contaminated wound, may need booster if last booster was > 5 years.

Clinical Cases

LITFL – CICM SAQ 2013.2 Q12

UMEM Educational Pearls, Tetanus

References / Resources

Tintinalli, Seventh Edition, Chapter 151: Tetanus

Crashing Patient, Scott Weingart, Bacterial and Toxin Infections, Reviewed on 3/6/14

CDC, Vaccines – Adult Immunization Schedule, Reviewed on 3/6/14

CDC, MMMWR, Preventing Tetanus, Diptheria, and Pertussis Among Adults, 2005, Reviewed on 3/6/14

Life in the Fast Lane, Critical Care Compendium, Tetanus, Reviewed on 3/6/14

EM:RAP, Richard Harrigan, September 2004, Tetanus Audio

151. Tetanus

Leave a Reply

Your email address will not be published. Required fields are marked *