History
Most cases of tetanus in the United States occur in patients with a history of underimmunization, either because they were never vaccinated or because they completed a primary series but have not had a booster in the preceding 10 years. From 1995 to 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, 3% had 3, and 9% had 4 or more. Persons who inject drugs also constitute a high-risk group.
The median incubation period is 7 days, and for most cases (73%), incubation ranges from 4 to 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 sometimes remember an injury, but often, the injury goes unnoticed. Patients may report a sore throat with dysphagia (early sign). The initial manifestation may be local tetanus, in which the rigidity affects only 1 limb or area of the body where the clostridium-containing wound is located. Patients with generalized tetanus present with trismus (ie, lockjaw) in 75% of cases. Other presenting complaints include stiffness, neck rigidity, restlessness, and reflex spasms.
Subsequently, muscle rigidity becomes the major manifestation. Muscle rigidity spreads in a descending pattern 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 as a consequence of 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.
Other symptoms include elevated temperature, sweating, elevated blood pressure, and episodic rapid heart rate.
Sustained contraction of facial musculature produces a sneering grin expression known as risus sardonicus.
Generalized tetanus
Generalized tetanus is the most commonly found form of tetanus in the United States, accounting for 85-90% of cases. The extent of the trauma varies from trivial injury to contaminated crush injury. The incubation period is 7-21 days, largely depending on the distance of the injury site from the central nervous system (CNS).
Trismus is the presenting symptom in 75% of cases; a dentist or an oral surgeon often initially sees the patient. Other early features include irritability, restlessness, diaphoresis, and dysphagia with hydrophobia, drooling, and spasm of the back muscles. These early manifestations reflect involvement of bulbar and paraspinal muscles, possibly because these structures are innervated by the shortest axons. The condition may progress for 2 weeks despite antitoxin therapy because of the time needed for intra-axonal antitoxin transport.
Localized tetanus
Localized tetanus involves an extremity with a contaminated wound and is of highly variable severity. It is an unusual form of tetanus, and the prognosis for survival is excellent.
Cephalic tetanus
Cephalic tetanus generally follows head injury or develops with infection of the middle ear. Symptoms consist of isolated or combined dysfunction of the cranial motor nerves (most frequently CN VII). Cephalic tetanus may remain localized or may progress to generalized tetanus. It is an unusual form of tetanus with an incubation period of 1-2 days. The prognosis for survival is usually poor.
Neonatal tetanus
Neonatal tetanus (tetanus neonatorum) is generalized tetanus that results from infection of a neonate. It primarily occurs in underdeveloped countries and accounts for as many as one half of all neonatal deaths. The usual cause is the use of contaminated materials to sever or dress the umbilical cord in newborns of unimmunized mothers.
The usual incubation period after birth is 3-10 days, which explains why this form of tetanus is sometimes referred to as the disease of the seventh day. The newborn usually exhibits irritability, poor feeding, rigidity, facial grimacing, and severe spasms with touch. Mortality exceeds 70%.
Physical Examination
Common first signs of tetanus are headache and muscular stiffness in the jaw (ie, lockjaw), followed by neck stiffness, difficulty swallowing, rigidity of abdominal muscles, spasms, and sweating. Patients often are afebrile. Stimulation of the posterior pharyngeal wall may elicit reflex spasms of the masseter muscles that cause patients to bite down as opposed to gag (spatula test). [23]
Severe tetanus results in opisthotonos, flexion of the arms, extension of the legs, periods of apnea resulting from spasm of the intercostal muscles and diaphragm, and rigidity of the abdominal wall. Late in the disease, autonomic dysfunction develops, with hypertension and tachycardia alternating with hypotension and bradycardia; cardiac arrest may occur.
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 the head or the trunk is the site of antecedent injury in 5% of patients.
Tetanic seizures may occur. Their presence portends a poor prognosis, and their frequency and severity are related to the severity of the disease. These 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.
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 (eg, sweating, fluctuating blood pressure, episodic tachydysrhythmia, and increased catecholamine release) 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.
Generalized tetanus
Sustained trismus may result in the characteristic sardonic smile (risus sardonicus) and persistent spasm of the back musculature may cause opisthotonos. Waves of opisthotonos are highly characteristic of the disease. With progression, the extremities become involved in episodes of painful flexion and adduction of the arms, clenched fists, and extension of the legs.
Noise or tactile stimuli may precipitate spasms and generalized convulsions. Involvement of the ANS may result in severe arrhythmias, oscillation of blood pressure, profound diaphoresis, hyperthermia, rhabdomyolysis, laryngeal spasm, and urinary retention. In most cases, the patient remains lucid.
Localized tetanus
In mild cases of localized tetanus, patients may have weakness of the involved extremity, presumably due to partial immunity; in more severe cases, they may have intense, 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; however, more severe cases tend to progress to generalized tetanus.
Cephalic tetanus
Cephalic tetanus is a rare form of the disease that is usually secondary to chronic otitis media or head trauma. It is characterized by variable CN palsies, most frequently involving CN VII. Ophthalmoplegic tetanus is a variant that develops after penetrating eye injuries and results in CN III palsies and ptosis.
Rapid progression is typical. Cephalic tetanus may remain localized or, especially if left untreated, progress to generalized tetanus.
Neonatal tetanus
Neonatal tetanus presents with an inability to suck 3-10 days after birth. Presenting symptoms include irritability, excessive crying, grimaces, intense rigidity, and opisthotonos. In general, the physical examination findings are similar to those of generalized tetanus.
Complications
Complications include spasm of the vocal cords and spasm of the respiratory muscles that cause interference with breathing. [24] Patients experience severe pain during each spasm. During the spasm, the upper airway can be obstructed, or the diaphragm may participate in the general muscular contraction.
Sympathetic overactivity is the major cause of tetanus-related death in the intensive care unit (ICU). Sympathetic hyperactivity usually is treated with labetalol at 0.25-1 mg/min as needed for blood pressure control or with morphine at 0.5-1 mg/kg/h by continuous infusion.
Neonatal tetanus follows infection of the umbilical stump, most commonly resulting from a failed aseptic technique in a mother who is inadequately immunized. Mortality for neonatal tetanus exceeds 90%, and developmental delays are common among survivors.
Before 1954, asphyxia from tetanic spasms was the usual cause of death in patients with tetanus. However, with the advent of neuromuscular blockers, mechanical ventilation, and pharmacologic control of spasms, sudden cardiac death has become the leading cause of death. Sudden cardiac death has been attributed to excessive catecholamine productions or the direct action of tetanospasmin or tetanolysin on the myocardium.
Nosocomial infections are common when hospitalization is prolonged. Secondary infections may include sepsis from decubitus ulcers, hospital-acquired pneumonia, and catheter-related infections. Pulmonary embolism is a particular problem in drug users and elderly patients.
Further complications include the following:
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Long bone fractures
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Glenohumeral joint and temporomandibular joint dislocations
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Hypoxic injury and aspiration pneumonia
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Clotting in the blood vessels of the lung
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Adverse effects of autonomic instability, [25] including hypertension and cardiac dysrhythmias
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Paralytic ileus, pressure sores, and urinary retention
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Malnutrition and stress ulcers
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Coma, nerve palsies, neuropathies, psychological aftereffects, and flexion contractures
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Image from "Number of Tetanus Cases Reported and Average Annual Incidence Rates, by State." Pascual FB, McGinley EL, Zanardi LR, et al: Tetanus surveillance—United States, 1998−2000. MMWR Surveill Summ. 2003 Jun 20;52(3):1-8.
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Image from "Number of Tetanus Cases Reported, Average Annual Incidence Rates, and Survival Status of Patients, by Age Group." Pascual FB, McGinley EL, Zanardi LR, et al: Tetanus surveillance—United States, 1998−2000. MMWR Surveill Summ. 2003 Jun 20;52(3):1-8.
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Image from "Number of Tetanus Cases Reported Among Persons With Diabetes or Injection-Drug Use (IDU), by Age Group." Pascual FB, McGinley EL, Zanardi LR, et al: Tetanus surveillance—United States, 1998−2000. MMWR Surveill Summ. 2003 Jun 20;52(3):1-8.
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Reported number of tetanus cases in the United States from 1947-2012. Image from National Notifiable Disease Surveillance System (NNDSS), Centers for Disease Control and Prevention (CDC).
