Tetanus, Emergency Medicine

Basics

Description

Rare disease in US but still prevalent in 3rd-world countries
About 30 cases per year in US
One-half of the cases involve people >50 yr of age
Majority of cases in US occur in the unvaccinated, >10 yr since last booster or IVDUs
500,000 " 1,000,000 cases worldwide
High mortality rates even with treatment
Incubation period:
- Inoculation to the appearance of the 1st symptoms:
  - 48 hr to 3 wk or more
- Period of onset:
  - <7 days " poor prognosis
  - Very poor prognosis if <48 hr from 1st symptom to initial reflex spasm
Neonatal tetanus:
- Due to infected umbilical stump
- Symptom onset in 2nd week of life when maternal antibodies decrease
- Rare in US but common in 3rd-world countries
- Worldwide, accounts for over one-half of all tetanus infections

Etiology

Clostridium tetani:
- Slender, motile, heat-sensitive, anaerobic gram-positive rod with a terminal spherical spore
- Spore characteristics
- Resistant to oxygen, moisture, temperature extremes
- Can survive indefinitely until it germinates
- Ubiquitous in soil and feces
When inoculated into a wound or devitalized tissue or injected IV as a contaminant of street drugs, the spores germinate under anaerobic conditions and produce 2 toxins.
Toxins:
- Tetanolysin:
  - Damages tissue
  - Does not cause clinical manifestations of tetanus infection
- Tetanospasmin:
  - Powerful neurotoxin
  - Disrupts the release of neurotransmitters such as ³-aminobutyric acid (GABA)
  - Responsible for the clinical manifestations
Muscle spasms
Autonomic instability
Uncontrolled motor activity

Diagnosis

Signs and Symptoms

Generalized

Most common type accounting for about 80% of all cases
Initial presentation:
- Muscle stiffness and pain
- Trismus (initial)
- Risus sardonicus (characteristic facial appearance)
Systemic symptoms:
- Irritability
- Restlessness
- Diaphoresis
Later manifestations:
- Muscle group rigidity
- Sudden burst of tonic contractions of muscle groups causing:
  - Opisthotonos
  - Flexion and adduction of the arms
  - Clenching of fists
  - Extension of the lower extremities
- Diaphragmatic spasm or paralysis:
  - May compromise respiration
Hypersympathetic state (most common cause of death):
- Begins in the 2nd week
- Dysrhythmias
- BP changes
- Diaphoresis
- Hyperthermia

Local

Less common form of disease, accounting for about 17% of all cases
Typical localized spasms around area of initial infection may:
- Be mild
- Persist for months before resolving
- Evolve to generalized form (13%)

Cephalic

Rare variant of disease
Follows head injury or otitis media
Spasm of lower cranial and facial muscles:
- Cranial nerve (CN) palsies, CN VII most common
May progress to generalized tetanus

Neonatal

Generalized form of tetanus occurring during the 1st weeks of life
Often caused by infection of umbilical stump
Clinical manifestations:
- Irritability
- Poor suck
- Facial grimacing
- Muscle spasms with touch
Very high mortality rate (50 " 100%)
Incubation period 1 " 2 wk

History

Investigate source of infection.
Acute skin wound not necessary to contract infection
>25% of infections occurred in the absence of known acute trauma.
Infections can occur from abscesses, ulcers, and gangrene.
Elicit tetanus immunization status.

Essential Workup

Perform complete physical exam focusing on cardiovascular and respiratory status, neurologic and CN exam.
Diagnosis of tetanus is clinical:
- Suspect in all cases of trismus
- No wound recalled in one-fifth of cases
- Full tetanus immunization almost eliminates diagnosis.

Diagnosis Tests & Interpretation

Often of limited or no benefit for diagnosis but useful for ruling out other etiologies or assessing complications of disease
Lab

CBC
Electrolytes, BUN, creatinine, glucose, calcium:
- For hypocalcemia
Strychnine level
ABG, pulse oximetry:
- For oxygenation status
Wound culture for C. tetani:
- Positive only about 30% of time
C. tetani titers:
- Will be useful only after the fact
CSF analysis:
- Normal in tetanus
- Exclude meningitis/encephalitis

Imaging
CT brain for altered mental status:

Normal in tetanus

Differential Diagnosis

Strychnine poisoning
Jaw muscles usually spared or not involved early in strychnine poisonings
Dystonic reaction to dopamine blockade
Infection:
- Meningitis
- Rabies
- Encephalitis
- Peritonitis
- Alveolar abscess
Black widow spider envenomation
Botulism
Serotonin syndrome
Hypocalcemic tetany
Bell palsy (cephalic form, before trismus)

Treatment

Pre-Hospital

Evaluate airway carefully:
- Endotracheal intubation complicated by trismus, vocal cord paralysis, and facial/neck rigidity
Avoid excessive stimulation because it may provoke tetany of musculature.

Initial Stabilization/Therapy

ABCs:
- Prophylactic intubation
- Require neuromuscular blockade due to trismus
- Establish IV 0.9% NS
- Monitor BP and cardiac rhythm (autonomic instability).
Administer benztropine or diphenhydramine to exclude dystonic reaction.

Ed Treatment/Procedures

Focuses on 3 goals:
- Stabilizing the patient and supportive care
- Neutralizing the toxin
- Removing any remaining organism
Stabilization and supportive care:
- Secure airway:
  - Prophylactic intubation may be necessary.
- Paralytic agent may be needed in the setting of trismus:
  - Succinylcholine should be used with caution due to the risk of hyperkalemia from upregulation of acetylcholine receptors.
- Treat muscle spasms with benzodiazepines; if large doses fail, can administer dantrolene.
Autonomic instability therapy:
- Occurs days to weeks after the onset of symptoms
- Tachydysrhythmia and hypertension:
  - No treatment universally effective
  - α- and ²-blockers can be tried but may cause worsening of symptoms (labetalol has been used for itsα- and ²-blocking effects).
  - Clonidine, magnesium, morphine, fentanyl, and epidural anesthesia may be tried.
- Hypotension:
  - Rule out septicemia and hypovolemia.
  - Initiate dopamine or dobutamine when low cardiac output.
  - Neutralization of the toxin
Human tetanus immune globulin (TIG):
- 3,000 " 6,000 U IM for both adults and children
- Administer before debridement of wound.
- Neutralizes unbound toxins
- No effect on toxin already bound in CNS
Removal of remaining organism:
- Limits the severity of the infection
- Debridement removes any necrotic tissue.
- Antibiotics are effective in eliminating C. tetani when used in conjunction with debridement
- Metronidazole is the antibiotic of choice.
- Penicillin is a viable alternative.
Prevention:
- Primary vaccination series should be completed by age 18 mo; children receive the booster at ages 4, 11, and then every 10 yr after.
- Diphtheria, pertussis, and tetanus vaccine for children <7 yr
- Tetanus diphtheria (Td) can be used for children >7 yr and adults.
- 1 dose of Tdap should be administered to everyone >11 yr of age if not received previously to address increase in pertussis.
- Clinical tetanus does not confer immunity.
- For clean, minor wounds:
  - Td should be given if unknown prior vaccination history or >10 yr since last booster.
- For tetanus-prone wounds:
  - Td should be given if unknown vaccination history or >5 yr since last booster.
  - TIG should be given if unknown vaccination or patient has never received the primary series.

Medication

Benztropine: 1 " 2 mg IV
Chlorpromazine: 10 " 50 mg IM
Diazepam (benzodiazepine): 5 " 10 mg (peds: 0.2 " 0.4 mg/kg) IV
Diphenhydramine: 50 mg IV
Dobutamine: 2.5 " 15 Όg/kg/min IV
Dopamine: 2 " 20 Όg/kg/min IV
Doxycycline: 100 mg IV q12h
Erythromycin: 500 mg IV q6h
Labetalol: 20 mg (peds: 0.3 " 1 mg/kg/dose) IV q10min up to 300 mg PRN " start infusion 2 mg/min (peds: 0.4 " 1 mg/kg/h max. 3 mg/kg/h as needed)
Metronidazole: 1 g (peds: 15 mg/kg) load, followed by 500 mg (7.5 mg/kg) IV q6h
Penicillin G: 1.2 mU on 2 separate entries (peds: 100,000 IU/kg/24 h) IV q6h for 10 days
Propranolol: 0.5 " 1 mg (peds: 0.01 " 0.1 mg/kg) IV
TIG:
- 250 IU IM
- Administer in separate site from Td toxoid
- For unimmunized or incompletely immunized in presence of tetanus prone wound
Td 0.5 mL IM

Follow-Up

Disposition

Admission Criteria
All patients should be admitted to an ICU.
Discharge Criteria
None for suspected generalized tetanus

Pearls and Pitfalls

Aggressive management is indicated for tetanus-prone wounds.

Additional Reading

American Academy of Pediatrics. Report of the Committee on Infectious Diseases. 29th ed. Elk Grove, IL: American Academy of Pediatrics; 2012.
Centers for Disease Control and Prevention (CDC). Updated recommendations for use of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine in adults aged 65 years and older " Advisory Committee on Immunization Practices (ACIP), 2012. MMWR Morb Mortal Wkly Rep. 2012;61:468 " 470.
Hsu SS, Groleau G. Tetanus in the emergency department: A current review. J Emerg Med. 2001;20:357 " 365.
McQuillan GM, Kruszon-Moran D, Deforest A, et al. Serologic immunity to diphtheria and tetanus in the United States. Ann Intern Med. 2002;136:660 " 666.

Codes

ICD9

037 Tetanus
771.3 Tetanus neonatorum

ICD10

A33 Tetanus neonatorum
A35 Other tetanus

SNOMED

76902006 Tetanus (disorder)
43424001 tetanus neonatorum (disorder)
240432006 Tetanus with trismus (disorder)
240431004 Cephalic tetanus
240429008 Localized tetanus

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