C. tetani spores usually enters the body through a wound or breach in the skin. In the presence of anaerobic (low oxygen) conditions, the spores germinate. Toxins are produced and disseminated via blood stream and lymphatic system. Toxins act at several sites within the central nervous system, including peripheral motor end plates, spinal cord, and brain, and in the sympathetic nervous system. The typical clinical manifestations of tetanus are caused when tetanus toxin interferes with release of neurotransmitters, blocking inhibitor impulses. This leads to unopposed muscle contraction and spasm. Seizures may occur, and the autonomic nervous system may also be affected.
Symptoms and Diagnosis
Tetanus is a clinical syndrome without confirmatory laboratory tests. The disease is characterized by painful muscular contractions, primarily of the masseter and neck muscles, secondarily of trunk muscles. A common first sign suggestive of tetanus in older children and adults is abdominal rigidity, although rigidity is sometimes confined to the region of injury. Generalized spasms occur, frequently induced by sensory stimuli. History of an injury or apparent portal of entry may be lacking. The organism is rarely recovered from the site of infection.
Tetanus is a medical emergency requiring hospitalization, immediate treatment with human tetanus immune globulin (TIG) (or equine antitoxin if human immune globulin is not available), a tetanus toxoid booster, agents to control muscle spasm, and aggressive wound care and antibiotics. If immunoglobulin is not available, tetanus antitoxin (equine origin) in a single large dose should be given intravenously, after testing for hypersensitivity.
Depending on the severity of disease, mechanical ventilation and agents to control autonomic nervous system instability may be required. An adequate airway should be maintained; tracheostomy, nasotracheal intubation, and/or mechanically assisted respiration, may be lifesaving. Sedation and muscle relaxant drugs should be used as indicated to control muscle spasms. Active immunization may be initiated concurrently with treatment.
The incubation period ranges from 3 to 21 days, usually about 10 days. In general, the further the injury site is from the central nervous system, the longer the incubation period. A shorter incubation period is associated with more severe disease, complications, and a higher chance of death. In neonatal tetanus, symptoms usually appear from 4 to 14 days after birth, averaging about 7 days.
On the basis of clinical manifestations, three different forms of tetanus have been described:
Generalized tetanus is the most common form, accounting for more than 80% of cases. Neonatal tetanus usually occurs because of umbilical stump infections. The most common initial sign is spasm of the muscles of the jaw or "lockjaw". This may be followed by painful spasms in other muscle groups in the neck, trunk, and extremities and by generalized, seizure-like activity or convulsions in severe cases. Generalized tetanus can be accompanied by nervous system abnormalities, as well as a variety of complications related to severe spasm and prolonged hospitalization. The clinical course of generalized tetanus is variable and depends on the degree of prior immunity, the amount of toxin present, and the age and general health of the patient. Even with modern intensive care, generalized tetanus is associated with death rates of 10%–20%.
Localized tetanus is an unusual form of the disease consisting of muscle spasms in a confined area close to the site of the injury. Although localized tetanus often occurs in people with partial immunity and is usually mild, progression to generalized tetanus can occur.
The rarest form, cephalic tetanus, is associated with lesions of the head or face and has been described in association with ear infections (otitis media). The incubation period is short, usually 1–2 days. Unlike generalized and localized tetanus, cephalic tetanus results in flaccid cranial nerve palsies rather than spasm. Spasm of the jaw muscles may also be present. Like localized tetanus, cephalic tetanus can progress to the generalized form.
Complications of Tetanus
- Nosocomial infections
- Pulmonary embolism
- Aspiration pneumonia
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