Tetanus

Definition

Tetanus is a condition in which there is prolonged contraction of skeletal muscle fibers.

Alternative names

Lockjaw

Causes, incidence and risk factors

Gram positive obligate anaerobe produces neurotoxin called as tetanospasmin that causes muscle contraction for prolonged period of time. The bacteria enter the body through deep cut or wound. As the infection progresses the toxin produced by the bacteria affect the body muscles. It affects the jaw muscles and there is spasm of jaw and hence the name lockjaw. The spread of toxin throughout the body causes general muscle stiffness and spasm in other body parts.

Symptoms

Symptoms appear between 3-21 days after infection. In newborns the symptoms appear between 4-14 days after birth. The time required for the symptoms to appear directly depends on the distance of site of infection from central nervous system. Clinical symptoms appear about a week after the infection.

The disease is mainly characterized by muscle spasm and the spasm is so powerful that it can tear the muscles or can cause cracks in the spinal cord.

There are four types of tetanus depending on the clinical observations.

In generalized tetanus the stiffness of muscles is in descending direction. Initially it starts with lockjaw (trismus) and facial paralysis (risus sardonicus) then stiffness of neck muscles, difficulty in swallowing and rigid pectoral and calf muscles. Other symptoms are elevated blood pressure, fever, sweating and intermittent rapid heart rate. The body spasm is frequent and may last for several minutes. The shape of the body in spasm state is called as opisthotonos. These symptoms appear for three to four weeks. It can take several weeks to recover fully.

The neonatal tetanus it is the generalized type of tetanus in newborns. If the mother is never vaccinated against tetanus there is lack of passive immunity in the newborn for the infection. The infection may be caused due to unhealed umbilical stump due to use of non-sterile instrument used to cut the cord. Deaths due to this type of tetanus are more common in developing countries.

In local tetanus there are persistent contractions in the area of infection for several weeks. Then they subside. There may be symptoms of local tetanus before generalized tetanus and such condition can be life threatening. This type of tetanus is milder form of tetanus.

In cephalic tetanus there is paralysis of facial nerves due to infection (by Clostridium tetani) of middle ear due to injury.

Signs and tests

The condition is diagnosed based on symptoms only. Ability to open the mouth widely is the negative sign for lockjaw. Doctor may perform a test. Touching the pharynx with sterile spatula results in biting the spatula due to involuntary muscle spasm is a positive sign for tetanus. If the spatula is expelled out as foreign body then it is a negative sign for tetanus. There is no laboratory test available for the diagnosis of tetanus.

Treatment

Treatment consists of use of antibiotics, immunoglobulin and vaccine.

Cleaning of wound and surgical removal of dead tissue is done. Metronidazole is used to treat the infection but it does not neutralize the toxin. Penicillin can be used but only if metronidazole is not available as it has the risk of increase in muscle spasm. Clindamycin and erythromycin are also used for the treatment. Anti-tetanospasmin immunoglobulin (from human) can be given as passive immunoglobulin. If anti-tetanospasmin immunoglobulin is not available then human immunoglobulin is given. All tetanus patients should be vaccinated after the disease.

For mild tetanus administration of immunoglobulin (intravenously or intramuscularly), intravenous administration of metronidazole, use of diazepam and tetanus vaccine has been recommended. For severe tetanus and lockjaw along with measures for mild tetanus hospitalization is required.

High calorie diet (3500-4000 calories per day) and 150 gm protein in diet per day have been recommended in order to overcome the increased metabolic strain due to increased muscle activity.

Expectations (Prognosis)

Without treatment death is possible. Infection of the wounds on the head and face is more dangerous than other body parts. If there is muscle spasm in throat there may be lack of oxygen (hypoxia) which may cause irreversible brain damage. If there is complete recovery from the acute illness then complete recovery is possible.

Complications

Fractures, obstruction of airways, respiratory arrest and heart failure due to muscular spasm; pneumonia and lack of oxygen due to spasm causing brain damage are the possible complications of tetanus.

Calling your health care provide

If there is open wound, wound in contact with soil or if not immunized for tetanus then calling health care provider is recommended.

Prevention

Prophylactic immunization or immunization after exposure can prevent the disease. Vaccination after every ten years or after every injury (whichever is less) and even after recovery from the disease has been recommended in order to prevent tetanus. Cleaning, proper care and treatment of wounds can prevent tetanus.

Reference

Nih.gov, wikipedia.com, mayoclinic.com