Acute tetanus

Background
  • Clostridium tetani spores enter skin through wound, make tetanospasmin toxin
  • 2001-2008 in US, 233 cases, 26 deaths
  • Mortality as high as 45%
  • Incubation is 2 to 56d
  • Spores found in soil and human and animal feces
    • Tetanus prone wounds include contaminated lacerations, abrasions, puncture wounds; crush, avulsion, or frostbite injuries are also vulnerable to tetanus [1]
    • Preferentially binds GABA and glycinergic neurons and blocks pre-synaptic release
      • Motor neurons undergo sustained excitatory discharge, producing spasms
  • The majority of clinical tetanus happen in the elderly.[2]

Clinical Features

Neonatal
  • From umbilical stump infection. Usually protected by passive maternal Abs
  • Symptoms - poor suck and failure to nurse, irritability, crying, grimacing
  • Usually with in 10 d of birth

Local
  • Rigidity of muscles near wound- may progress to generalized

Generalized
  • Most common form of tetanus
  • Usually begins with trismus (spasm of the masticator muscle group) with gradual onset of spasm of muscle groups in the trunk and extremities
  • Spasms exacerbated by external stimuli (light or sudden sound)
  • Patients can lose ability to breath during prolonged spasms
  • Respiratory failure is main cause of death
  • Patients are conscious and alert
  • Hypersympathetic state with sweating, hypertension, tachycardia, fever

Cephalic
  • Follow injuries to head or otitis media
  • Get cranial nerve dysfunction- usually cranial nerve 7

Differential Diagnosis

Jaw Spasms

Evaluation
  • Diagnosis is clinical
  • Progressive symptoms[3]
    • Alert and able to communicate
    • Trismus - lockjaw (50%-75% of patients)
    • Sardonic smile (risus sardonicus) - other facial muscles become involved
    • Minor stimuli such as touch or noise start tetanic contractions
    • Difficulty swallowing
    • Long bone fractures, tendon rupture
    • Opisthotonus - lumbar lordosis with the neck and legs extended and the arms flexed at the elbows
    • Laryngospasm
    • Autonomic instability
    • Sympathetic nervous system hyperactivity, including tachycardia, sweating, arrhythmias, and hypertension
  • No laboratory testing is used to diagnose tetanus; wound cultures are often negative

Management
  • Before wound debridement, immunoglobulin (TIG) directly into the wound and IM
    • Dose: 3000-6000 units IM with adequate mL to wound
    • Does not reverse toxin already bound to CNS. Binds circulating toxin
  • Tetanus toxoid; patients do NOT develop immunity after tetanus infection

Supportive Care
  • Place patient in a quiet room
  • Provide sedation with Benzodiazepines or phenobarbital
  • Airway management via intubation or tracheostomy should be performed when patient exhibits dysphagia or respiratory difficulties
  • Autonomic dysfunction management with magnesium sulfate or labetalol, morphine and clonidine
  • Magnesium sulfate has several desirable attributes for control of spasticity and autonomic dysfunction in tetanus[4]
    • Acts as a presynaptic neuromuscular blocker by antagonizing calcium in the neuromuscular junction and myocardium
    • Blocks the release of catecholamines and has anticonvulsant properties
    • Often available in low-resource settings

Antibiotics

Penicillin
  • Although once the drug of choice it is now no longer recommended since it may potentiate the effect of tetanus toxin by inhibiting the GABA receptors[5]

See Also

References
  1. Auerbach PS. Wilderness Medicine. Philadelphia: Mosby Elsevier; 2007.
  2. Talan DA, et al. Tetanus immunity and physician compliance with tetanus prophylaxis practices among emergency department patients presenting with wounds. Ann Emerg Med. 2004 Mar;43(3):305-14.Pubmed
  3. 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, (Ch) 127:p 1681-1686
  4. Wangmo KP, Teng M, Henker R, Kinnear S, Tshering J, Wang NE. Survival of a Patient With Tetanus in Bhutan Using a Magnesium Infusion Managed Only by Clinical Signs. Wilderness & Environmental Medicine. 2014;25(2):194-197. doi:10.1016/j.wem.2013.11.006.
  5. Ganesh Kumar AV. Benzathine penicillin, metronidazole and benzyl penicillin in the treatment of tetanus: a randomized, controlled trial .Ann Trop Med Parasitol. 2004 Jan;98(1):59-63 PMID 15000732
Moll JL, Carden DL. Tetanus. In: Tintinalli JE, Stapczynski J, Ma O, Yealy DM, Meckler GD, Cline DM. eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 8e New York, NY: McGraw-Hill; 2016. http://accessmedicine.mhmedical.com/content.aspx?bookid=1658&sectionid=109435736. Accessed December 01, 2017.
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