EM@3AM: Tetanus

Authors: Christopher J. Nelson, MD (EM Resident Physician, UTSW, Dallas, TX); Elizabeth Morley, PA-C (UTSW, Dallas, TX); Prayag Mehta, MD (Assistant Professor of EM, UTSW, Dallas, TX); Joby Thoppil, MD, PhD (Assistant Professor of EM, UTSW, Dallas, TX) // Reviewed by: Alex Koyfman, MD (@EMHighAK); Brit Long, MD (@long_brit)

Welcome to EM@3AM, an emDOCs series designed to foster your working knowledge by providing an expedited review of clinical basics. We’ll keep it short, while you keep that EM brain sharp.

A 38-year-old male with a history of injection drug use presents to the emergency department (ED) with one day of progressively worsening, pressure-like chest pain radiating to his back. He appears diaphoretic and in moderate distress. He has had difficulty opening his mouth.

Triage vital signs include BP 143/98, HR 115, T 99.2, RR 20, SpO2 98% on room air. On exam, he is tachycardic, diaphoretic, and in acute distress. He endorses tenderness throughout his thoraco-lumbar spine. Neurological evaluation demonstrates increased tone in all extremities. Skin exam reveals two abscesses on his upper extremities. An MRI of the spine is unremarkable. Reexamination reveals new spasmodic neck stiffening, jaw clenching, and arching of his back.

What is the likely diagnosis?

Answer: Tetanus



  • Rarely seen in developed countries secondary to high rates of immunization
  • Mortality approaches 28% and is associated with respiratory compromise and severe autonomic instability1
  • Worldwide deaths decreasing – ~275,000 in 1997 down to 14,132 in 20112
    • Higher proportion in low resource settings2
  • At risk populations include injection drug users, unimmunized individuals, foreign born individuals, and the elderly3,4,5
  • Tetanus is caused by Clostridium tetani, a spore producing obligate anaerobic gram-positive rod1
    • Spores allow the bacteria to survive environmental extremes



  • Clostridium tetani produces a neurotoxin that binds GABA and glycinergic neurons1
  • The toxin blocks pre-synaptic release, leading to a loss of inhibitory action on motor and autonomic neurons1,6
  • Incubation period of 3-21 days1
    • Shorter with decreased distance between the injury site and the central nervous system1
    • Shorter incubation periods are associated with a higher chance of death1
  • Four clinical forms:1,5,7,8
    • Generalized
      • Usually begins with trismus and gradual onset of spasm of muscle groups in the trunk and extremities
    • Localized
      • Muscle rigidity near area of injury
      • May progress to generalized
    • Cephalic
      • Almost always after an apparent head wound or otitis media
      • Cranial nerve involvement (especially facial nerve), dysphagia, trismus
    • Neonatal
      • Due to infection of the umbilical stump, mostly from lack of maternal immunization
      • Occurring in the first week of life, irritability, and poor feeding rapidly progress into generalized spasms
      • Developing world cultural practices like application of clarified butter (ghee), cow dung and ashes, wrapping newborn in inverted sheep skin


History and Exam:

  • Evaluation history of immunization
    • Completion of primary series
    • Date of last booster
  • Social history
    • Injection drug use
    • Black tar heroin originating from Mexico has been associated with tetanus when compared to powder heroin3
  • Medication history
    • Dystonic/serotonin/neuroleptic malignant syndromes can mimic a tetanus presentation
  • Physical exam
    • Risus Sardonicus (“sardonic smile”)
    • Trismus (“lock-jaw”) in 75-80 % of cases8
    • Abdominal rigidity
    • Tonic contraction of skeletal muscles
    • Painful intermittent intense muscular spasms
      • Opisthotonos – abnormal posturing from arching of the head, neck and spine with flexion of the arms and extension of the legs.
      • Often triggered by sensory stimuli
    • Autonomic instability and hyperactivity (hypertension, tachycardia, diaphoresis, hyperthermia)



  • Botulism
    • Descending symmetrical flaccid paralysis1,9
  • Conversion Disorder
  • Dystonic reaction1,7,8
    • Associated with antipsychotic, anti-emetics, and antidepressants
    • Lateral head turning
  • Hypocalcemic tetany
    • Trismus is rare1
  • Neuroleptic malignant syndrome8
    • Associated with antipsychotics and antiemetics
    • Presents with altered mental status, “lead pipe” rigidity, autonomic instability, hyperthermia
  • Rabies
  • Serotonin syndrome
    • hyperpyrexia, clonus, seizures, dilated pupil, muscle twitching, ataxia, and loss of consciousness1
  • Strychnine poisoning1,8
    • Associated with gopher poison
    • Onset within 20 minutes of exposure


ED Evaluation:

  • Clinical Diagnosis
  • CBC (may have ↑ WBC), CMP, CK, lactate, blood cultures
  • Serum and urine strychnine levels can be ordered but will not return in the ED



  • Close assessment of airway and breathing
  • Source Control – early wound debridement/incision and drainage
  • Tetanus Immune Globulin (TIG) 500 U IM
    • May be injected directed into wound as well
  • Tetanus toxoid vaccine as appropriate
  • Antimicrobial therapy
    • Metronidazole 500mg IV Q6 hours10
    • Penicillin G 2 to 4 million units IV Q4-6 hours10
  • Control muscle spasm11
    • Diazepam – 5mg increments8
    • Lorazepam – 2mg increments8
    • Midazolam – 5-15mg/hr infusion8
      • Does not contain propylene glycol that may lead to lactic acidosis with diazepam and lorazepam
    • Management of dysautonomia
      • Magnesium sulfate for autonomic dysfunction and as adjunctive treatment for controlling spasms
        • 40mg/kg over 30 minutes followed by 2 g per hours for patient over 45kg8
      • Admission



  • Injection drug users and unimmunized at risk
  • Vaccine status must be considered in all types of wounds
  • Consider administering tetanus toxoid vaccine in the ED for at-risk populations with wound infections, particularly IVDU
  • Found in developing countries, acute tetanus is uncommon in the US and early signs of tetanus may create diagnostic dilemmas
  • Even with optimal treatment, the mortality of tetanus is still high
  • Strychnine poisoning should be high on the differential
  • Close airway monitoring needed


  1. Ataro P, Mushatt D, Ahsan S. Tetanus: a review. Southern Medical Journal. 2011;104(8):613-7. DOI: 10.1097/SMJ.0b013e318224006d.
  2. Rushdy AA, White JM, Ramsay ME, et al. Tetanus in England and Wales, 1984-2000. Epidemiol Infect. 2003;130(1):71-77.
  3. Chambers, HF. Skin and Soft Tissue Infections in Persons Who Inject Drugs. Infectious Disease Clinics of North America. 2021;35(1): 169-181.
  4. Lu P, et al. Adult Vaccination Disparities among Foreign Born Populations in the United States, 2012. American Journal of Preventive Medicine. 2014;47(6):722-733.
  5. Tejpratap SP, Tiwari MD, et al. Tetanus. Pinkbook. Centers of Disease Control and Prevention (CDC): Epidemiology and Prevention of Vaccine Preventable Diseases. 2020;13.
  6. Hassel B. Tetanus: Pathophysiology, Treatment, and the Possibility of Using Botulinum Toxin against Tetanus-Induced Rigidity and Spasms. Toxins. 2013;5(1):73-83. DOI: 10.3390/toxins5010073.
  7. Birch T, Bleck T. Tetanus (Clostridium tetani). Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases, Ninth edition. 2019;9(244):2948-2953.e2.
  8. Thwaites, Louise, MD. Tetanus. UpToDate. 11 November 2021. https://www.uptodate.com/contents/tetanus#H29. Accessed January 7, 2022.
  9. Lavender TW, McCarron B. Acute infections in intravenous drug users. Clin Med (Lond). 2013;13(5):511-3. DOI: 10.7861/clinmedicine.13-5-511.
  10. Ganesh Kumar AV. Benzathine penicillin, metronidazole and benzyl penicillin in the treatment of tetanus: a randomized, controlled trial. Ann Trop Med Parasitol. 2004;98(1):59-63.
  11. Fernandez-Frackelton M: Bacteria, in Marx JA, Hockberger RS, Walls RM, et al (eds). Rosen’s Emergency Medicine: Concepts and Clinical Practice, ed 7. St. Louis, Mosby, Inc.; 2010;121:1579-1588.
  12. Finkelstein, P, et al. Tetanus: A Potential Public Health Threat in Times of Disaster. Prehospital and Disaster Medicine. 2017;32(3):339-342.

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