Tetanus

Facial muscle spasm produces a characteristic expression with a fixed smile and elevated eyebrows (risus sardonicus). Rigidity or spasm of abdominal, neck, and back muscles and sometimes opisthotonos (generalized rigidity of the body with arching of the back and neck) may occur. Sphincter spasm causes urinary retention or constipation. Dysphagia may interfere with nutrition.

Characteristic painful, generalized tonic spasms with profuse sweating are precipitated by minor disturbances such as a draft, noise, or movement. Mental status is usually clear, but coma may follow repeated spasms. During generalized spasms, patients are unable to speak or cry out because of chest wall rigidity or glottal spasm. Rarely, fractures result from sustained spasms.

Spasms also interfere with respiration, causing cyanosis or fatal asphyxia.

Temperature is only moderately elevated unless a complicating infection, such as pneumonia, is present. Respiratory and pulse rates are increased. Reflexes are often exaggerated. Protracted tetanus may manifest as a very labile and overactive sympathetic nervous system, including periods of hypertension, tachycardia, and myocardial irritability.

Respiratory failure is the most common cause of death. Laryngeal spasm and rigidity and spasms of the abdominal wall, diaphragm, and chest wall muscles cause asphyxiation. Hypoxemia can also induce cardiac arrest, and pharyngeal spasm leads to aspiration of oral secretions with subsequent pneumonia, contributing to a hypoxemic death. Pulmonary embolism is also possible. However, the immediate cause of death may not be apparent.

In localized tetanus, there is spasticity of muscles near the entry wound but no trismus; spasticity may persist for weeks.

Cephalic tetanus is a form of localized tetanus that affects the cranial nerves. It is more common among children; in them, it may occur with chronic otitis media or may follow a head wound. Incidence is highest in Africa and India. All cranial nerves can be involved, especially the 7th. Cephalic tetanus may become generalized.

Tetanus in neonates is usually generalized and frequently fatal. It often begins in an inadequately cleansed umbilical stump in children born of inadequately immunized mothers. Onset during the first 2 weeks of life is characterized by rigidity, spasms, and poor feeding. Bilateral deafness may occur in surviving children.

The patient should be kept in a quiet room. Several principles should guide all therapeutic interventions:

Because dirt and dead tissue promote C. tetani growth, prompt, thorough debridement, especially of deep puncture wounds, is essential. Antibiotics are not substitutes for adequate debridement and immunization but typically are given.

The benefit of human-derived antitoxin depends on how much tetanospasmin is already bound to the synaptic membranes—only free toxin is neutralized. For adults, human TIG 3000 to 6000 units IM is given once; this large volume may be split and given at separate sites around the wound. Dose can range from 500 to 6000 units, depending on wound severity, but some authorities feel that 500 units are adequate.

Antitoxin of animal origin is far less preferable because it does not maintain the patient’s serum antitoxin level well and risk of serum sickness is considerable. If horse serum must be used, the usual dose is 50,000 units IM or IV (CAUTION: See Skin testing Skin testing ).

If necessary, IVIG or antitoxin can be injected directly into the wound, but this injection is not as important as good wound care.

Tetanus infection does not confer immunity, so unless their vaccination history indicates completion of a full primary series, patients should receive a full primary tetanus vaccination series using an age-appropriate preparation (see Prevention Prevention Tetanus is acute poisoning from a neurotoxin produced by Clostridium tetani. Symptoms are intermittent tonic spasms of voluntary muscles. Spasm of the masseters accounts for the name... read more below). Antitoxin and vaccine should be injected into different body sites to avoid neutralizing the vaccine.

Drugs are used to manage spasms.

Benzodiazepines are the standard of care to control rigidity and spasms. They block reuptake of an endogenous inhibiting neurotransmitter, gamma-aminobutyric acid (GABA), at the GABA_A receptor.

Diazepam can help control seizures, counter muscle rigidity, and induce sedation. Dosage varies and requires meticulous titration and close observation. The most severe cases may require 10 to 30 mg IV every 1 to 4 hours. Less severe cases can be controlled with 5 to 10 mg orally every 2 to 4 hours. Dosage varies by age:

Diazepam has been used most extensively, but midazolam (adults, 0.1 to 0.3 mg/kg/hour IV infusion; children, 0.06 to 0.15 mg/kg/hour IV infusion) is water soluble and preferred for prolonged therapy. Midazolam reduces risk of lactic acidosis due to propylene glycol solvent, which is required for diazepam and lorazepam, and reduces risk of long-acting metabolites accumulating and causing coma.

Benzodiazepines may not prevent reflex spasms, and effective respiration may require neuromuscular blockade with vecuronium 0.1 mg/kg IV or other paralytic drugs and mechanical ventilation. Pancuronium has been used but may worsen autonomic instability. Vecuronium is free of adverse cardiovascular effects but is short-acting. Longer-acting drugs (eg, pipecuronium, rocuronium) also work, but no randomized clinical comparative trials have been done.

Intrathecal baclofen (a GABA_A agonist) is effective but has no clear advantage over benzodiazepines. It is given by continuous infusion; effective doses range between 20 and 2000 mcg/day. A test dose of 50 mcg is given first; if response is inadequate, 75 mcg may be given 24 hours later, and 100 mcg may be given 24 hours after that. Patients who do not respond to 100 mcg are not candidates for chronic infusion. Coma and respiratory depression requiring ventilatory support are potential adverse effects.

Dantrolene (loading dose 1.0 to 1.5 mg/kg IV, followed by infusion of 0.5 to 1.0 mg/kg every 4 to 6 hours for ≤ 25 days) relieves muscle spasticity. Dantrolene given orally can be used in place of infusion therapy for up to 60 days. Hepatotoxicity and expense limit its use.

Morphine may be given every 4 to 6 hours to control autonomic dysfunction, especially cardiovascular; total daily dose is 20 to 180 mg.

Beta-blockade is used to control episodes of hypertension and tachycardia, but use of long-acting drugs such as propranolol is not recommended. Sudden cardiac death is a feature of tetanus, and beta-blockade can increase risk; however, esmolol, a short-acting beta-blocker, has been used successfully. IV atropine has been used at high doses; blockade of the parasympathetic nervous system markedly reduces excessive sweating and secretions. Lower mortality has been reported in clonidine-treated patients than in those treated with conventional therapy.

Magnesium sulfate at doses that maintain serum levels between 4 to 8 mEq/L (eg, 4 g bolus followed by 2 to 3 g/hour by IV continuous infusion) has a stabilizing effect, eliminating catecholamine stimulation. Patellar tendon reflex is used to assess overdosage. Tidal volume may be impaired, so ventilatory support must be available.

Other drugs that may prove useful include

Corticosteroids are of unproven benefit; their use is not recommended.

The role of antibiotic therapy is minor compared with wound debridement and general support. Typical antibiotics include penicillin G 6 million units IV every 6 hours, doxycycline 100 mg IV 2 times a day, and metronidazole 500 mg IV every 6 to 8 hours.

In moderate or severe cases, patients should be intubated. Mechanical ventilation is essential when neuromuscular blockade is required to control muscle spasms that impair respirations.

IV hyperalimentation avoids the hazard of aspiration secondary to gastric tube feeding. Because constipation is usual, stools should be kept soft. A rectal tube may control distention. Bladder catheterization is required if urinary retention occurs.

Chest physiotherapy, frequent turning, and forced coughing are essential to prevent pneumonia. Analgesia with opioids is often needed.