Tetanus: Diagnosis and Differentials

Author: Daniel J Dire, MD, FACEP, FAAP, FAAEMAuthor Information and Disclosures

Editors: Theodore Gaeta, DO, MPH; Francisco Talavera, PharmD, PhD; Eddy Lang, MDCM, CCFP (EM), CSPQ; John Halamka, MD; Charles V Pollack, Jr, MD, MA, FACEPEditor Information

Clinical

History:

• From 1995-2000, 81% of cases in the United States were generalized tetanus, 15% were localized, 3% were cephalic, and 1 case of neonatal tetanus was reported. From 1995-1997, 54% of the reported cases in the United States had an unknown tetanus vaccination history, 22% had no known previous tetanus vaccination, 9% had 1 previous dose, 3% had 2 previous doses, 3% had 3 previous doses, and 9% had 4 or more previous doses.
  
  
  • The last reported case of neonatal tetanus in the United States was in 1998; this was only the second case since 1989.
  
  
  
  • Most reported cases of tetanus worldwide are the neonatal type.
  
  


• The median incubation period is 7 days, and, for most cases (73%), incubation ranges from 4-14 days.
  
  
  • The incubation period is shorter than 4 days in 15% of cases and longer than 14 days in 12% of cases.
  
  
  
  • Patients with clinical manifestations occurring within 1 week of an injury have more severe clinical courses.


• Patients with generalized tetanus present with trismus (ie, lockjaw) in 75% of cases.
  
  
  • Other presenting complaints include stiffness, neck rigidity, dysphagia, restlessness, and reflex spasms.
  
  
  
  • Subsequently, muscle rigidity becomes the major manifestation.
  
  
  
  • Muscle rigidity spreads from the jaw and facial muscles over the next 24-48 hours to the extensor muscles of the limbs.
  
  
  
  • Dysphagia occurs in moderately severe tetanus due to pharyngeal muscle spasms, and onset is usually insidious over several days.
  
  
  
  • Reflex spasms develop in most patients and can be triggered by minimal external stimuli such as noise, light, or touch. The spasms last seconds to minutes; become more intense; increase in frequency with disease progression; and can cause apnea, fractures, dislocations, and rhabdomyolysis.
  
  
  
  • Laryngeal spasms can occur at any time and can result in asphyxia.
  
  
  
• Sustained contraction of facial musculature produces a sneering grin expression known as risus sardonicus.

Physical:

• The lower extremity is the site of antecedent acute injury in 52% of patients, the upper extremity is the site of antecedent injury in 34% of patients, and head or trunk is the site of antecedent injury in 5% of patients.



• Autonomic dysfunction in patients with severe tetanus manifests as extremes in blood pressure, dysrhythmias, and cardiac arrest.



• Neonatal tetanus presents with an inability to suck 3-10 days after birth. Presenting symptoms include irritability, excessive crying, grimaces, intense rigidity, and opisthotonus.



• Tetanic seizures may occur and portend a poor prognosis.
  
  
  • Frequency and severity of seizures are related to severity of the disease.
  
  
  
  • Seizures resemble epileptic seizures with the presence of a sudden burst of tonic contractions.
  
  
  
  • However, the patient does not lose consciousness and usually experiences severe pain.
  
  
  
  • Seizures frequently occur in the muscle groups causing opisthotonos, flexion and abduction of the arms, clenching of the fists against the thorax, and extension of the lower extremities.


• Localized tetanus is characterized by painful spasms of the group of muscles in close proximity to the site of injury. This disorder may persist for several weeks but is usually self-limiting.



• Cephalic tetanus is usually secondary to chronic otitis media or head trauma.
  
  
  • Cephalic tetanus is characterized by variable cranial nerve (CN) palsies; CN VII is most frequently involved.
  
  
  
  • Ophthalmoplegic tetanus is a variant that develops after penetrating eye injuries and results in CN III palsies and ptosis.
  
  
  
  • Patients with cephalic tetanus who are untreated progress to generalized tetanus.
  
  
  


• Patients with tetanus may present with abdominal tenderness and guarding, mimicking an acute abdomen. Exploratory laparotomies have been performed before the correct diagnosis was apparent.



• Tetanospasmin has a disinhibitory effect on the autonomic nervous system (ANS).
  
  
  • ANS dysfunction becomes progressively evident as the level of toxin in the CNS increases.
  
  
  
  • ANS disturbances, such as sweating, fluctuating blood pressure, episodic tachydysrhythmia, and increased release of catecholamines, are observed.
  
  
  
  • Drugs with beta-blocker effects have been used to control the cardiovascular manifestations of ANS instability, but they also have been associated with increased risk of sudden death.

Causes:

• Only 12-14% of patients with tetanus in the United States have received a primary series of tetanus toxoid. During 1998-2000, only 6% of all patients with tetanus were known to be current with tetanus immunization, with no fatal cases reported among this group.
  
  
  • In 73% of patients with tetanus in the United States, tetanus occurred after an acute injury, including puncture wounds (50%), lacerations (33%), and abrasions (9%).
  
  
  
  • Of those who obtained medical treatment of their injury in the United States from 1998-2000, 96% were administered tetanus immune globulin as part of their treatment; 55% of patients required the use of assisted ventilation and 31% of these patients died.
  • Stepping on a nail accounted for 32% of the puncture wounds.
  
  
  
  • Tetanus can occur in burn victims; in patients receiving intramuscular injections; in persons obtaining a tattoo; and in persons with frostbite, dental infections (eg, periodontal abscesses), penetrating eye injuries, and umbilical stump infections.
  
  
  
  • Other reported risk factors include diabetes, chronic wounds (eg, skin ulcers, abscesses, gangrene), parenteral drug abuse, and recent surgery (4% of US cases).
  
  
  
  • Twelve percent of patients with tetanus in the United States from 1998-2000 had diabetes (with a mortality rate of 31%) compared with 2% during 1995-1997. Of these patients, 69% had acute injuries while 25% had gangrene or a diabetic ulcer.
  
  
  
  • The median time interval between surgery and onset of tetanus is 7 days.


• Tetanus has been reported after tooth extractions, root canal therapy, and intraoral soft tissue trauma.

• Worldwide risk factors for neonatal tetanus are as follows:
  
  
  • Unvaccinated mothers, home delivery, and unhygienic cutting of the umbilical cord increase susceptibility to tetanus.
  
  
  
  • History of neonatal tetanus in a previous child is a risk factor for subsequent neonatal tetanus.
  
  
  
  • Potentially infectious substances applied to the umbilical stump (eg, animal dung, clarified butter) are risk factors for neonates.


• Immunity from tetanus decreases with advancing age.
  
  
  • Serologic testing for immunity has revealed a low level among elderly individuals in the United States.
  
  
  
  • Approximately 50% of adults older than 50 years are nonimmune because they never were vaccinated or do not receive appropriate booster doses.
  
  
  
  • Prevalence of immunity to tetanus in the United States is greater than 80% for those aged 6-39 years but only 28% for persons older than 70 years.

Differentials

Other Problems to be Considered:

Intraoral disease
Odontogenic infections
Globus hystericus
Hepatic encephalopathy
Hysteria
Strychnine poisoning
Acute abdomen
Intracranial hemorrhage

Workup

Lab Studies:

• No specific laboratory tests exist for determining the diagnosis of tetanus. The diagnosis is clinically based on the presence of trismus, dysphagia, generalized muscular rigidity, and/or spasm.



• Laboratory studies may demonstrate a moderate peripheral leukocytosis.

Other Tests:

• An assay for antitoxin levels is not readily available. However, a level of 0.01 IU/mL or greater in serum is generally considered protective, making the diagnosis of tetanus less likely.



• Cerebral spinal fluid (CSF) study findings are usually within normal limits.

• The spatula test is one diagnostic bedside test.
  
  
  • This simple test involves touching the oropharynx with a spatula or tongue blade.
  
  
  
  • This test typically elicits a gag reflex, and the patient tries to expel the spatula (ie, a negative test result).
  
  
  
  • If tetanus is present, patients develop a reflex spasm of the masseters and bite the spatula (ie, a positive test result).
  
  
  
  • In 400 patients, this test had a sensitivity of 94% and a specificity of 100%.
  
  
  
  • No adverse sequelae from this procedure (eg, laryngeal spasm) were reported.

• Dislocations, Mandible
• Encephalitis
• Hypocalcemia
• Meningitis
• Peritonsillar Abscess
• Rabies
• Spider Envenomations, Widow
• Stroke, Hemorrhagic
• Subarachnoid Hemorrhage
• Toxicity, Medication-Induced Dystonic Reactions

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