Tetanus is an acute specific infection caused by the invasion of tetanus bacillus into body wounds, growth and reproduction, and production of toxins. Tetanus bacillus is widely present in soil and human and animal feces, is a Gram stain-positive anaerobic bacillus. Tetanus bacillus and its toxin can not invade the normal skin and mucous membranes, so tetanus are occurring in the post-injury. All open injuries such as inflammatory injuries, open fractures, burns, and even small wounds such as forest spikes or rusty nail puncture wounds, may occur tetanus. Tetanus is also seen in newborns with unsterile umbilical cord stumps and poorly sterilized abortions; and can occasionally occur after gastrointestinal surgery to remove foreign bodies left in the body for years. The presence of tetanus bacilli in a wound does not necessarily lead to morbidity; in addition to the occurrence of tetanus being related to the virulence and number of bacteria or the lack of immunity, local wound hypoxia is a factor favoring morbidity. Therefore, when the wound is narrow and deep, ischemic, necrotic tissue, poor drainage, and mixed with other need to oxidize pus bacteria infection and cause local hypoxia in the wound, tetanus will easily occur. The calcium chloride contained in the soil can promote tissue necrosis, which is conducive to the propagation of anaerobic bacteria, so the rusty nail with soil or the stab wound of the forest thorn can easily cause tetanus. Wu Chunfu, Department of Surgery, Wuxi Hospital of Traditional Chinese Medicine
Pathophysiology
The tetanus bacillus is the cause of tetanus as long as the local growth and reproduction of the wound, and the exotoxin produced is the cause of tetanus. There are two kinds of exotoxins: spasmotoxin and hemolytic toxin. The former is the main toxin that causes symptoms and has a special affinity for nerves and can cause myospasm; the latter can cause local necrosis of tissues and myocardial damage. The tetanus spasm toxin reaches the anterior horn gray matter of the spinal cord or the motor nucleus of the brainstem by the blood circulation and the lymphatic system, and is attached to serum globulin. Upon reaching the central nervous system, the toxin binds mainly to gangliosides in the synaptic vesicle membranes in the gray matter, preventing them from releasing inhibitory transmitters (glycine or aminobutyric acid), so that the alpha motor nervous system loses its normal inhibitory properties, causing characteristic generalized transverse muscle tension contractions or paroxysmal spasms. Toxins can also affect sympathetic nerves, resulting in profuse sweating, unstable blood pressure, and increased heart rate. Therefore, tetanus is a toxaemia.
Clinical manifestations
The incubation period of tetanus is 6-10 days on average, but also shorter than 24 hours or up to 20-30 days, or even months, or only after the removal of foreign bodies that have remained in the body for many years, such as bullets or shrapnel. Neonatal tetanus usually develops about 7 months after the umbilical cord is broken, so it is commonly known as “seven days of wind”. Generally speaking, the shorter the duration of the incubation period or prodromal symptoms, the more severe the symptoms and the higher the mortality rate.
Patients first have prodromal symptoms such as weakness, dizziness, headache, tension and swelling of the biting muscles, irritability and yawning. These prodromal symptoms usually last 12 to 24 hours, followed by the typical strong contraction of the muscles, initially the bite muscles, followed by the facial muscles, neck and neck muscles, back and abdominal muscles, limb muscles, diaphragm and intercostal muscles. The patient begins to feel difficulty in chewing and opening the mouth, followed by a tight closure of the teeth; the facial expression muscle group is in paroxysmal spasm, giving the patient a unique “bitter smile” expression. In the case of cervical muscle spasm, the neck is straightened, the head is slightly tilted back, and the head nodding cannot be done. The dorsal and abdominal muscles contract at the same time, but the dorsal muscles are stronger, so that the waist is convex and the head and feet are flexed backward, forming a dorsal arch, which is called “corkscrew”. When the limb muscles contract, because the flexors are strong through the extensors, the limbs can appear flexed knees, bent elbows, half-clenched fists and other postures. On the basis of continuous tense contraction, any slight stimulus, such as light, sound, vibration or touching the patient’s body, can trigger spasms and convulsions of the whole body muscles. Each seizure lasts for several seconds to several minutes, and the patient’s face is cyanotic, breathing rapidly, foaming at the mouth, salivating, grinding teeth, tilting the head back frequently, twitching the limbs, sweating profusely, and in great pain. During the interval between attacks, the pain is slightly reduced, but the muscles still cannot be completely relaxed. Intense muscle spasms can sometimes break the muscle and even fracture it. Spasm of the bladder hand sphincter can in turn cause urinary retention. Persistent spasm of the respiratory muscle groups and diaphragm can cause respiratory arrest, resulting in the death of the patient. During the disease, the patient is always conscious and usually does not have a high fever. The presence of a high fever often indicates the development of pneumonia. The duration of the disease is usually 3 to 4 weeks. From the second week onwards, the symptoms gradually decrease as the illness progresses. However, for an extended period after healing, certain muscle groups sometimes remain tense and hyperreflexic.
A small number of patients present with localized tetanus. There is only a persistent wistful tonicity of the injured muscles, which can last for weeks to months and then gradually subsides. However, it can sometimes develop into generalized tetanus. The prognosis for localized tetanus is better.
Complications
In addition to the fractures, urinary retention and respiratory arrest described above, the following complications can occur.
1. asphyxia: due to persistent spasm of the larynx and respiratory muscles and obstruction of the trachea by mucus and phlegm.
2, lung infection: laryngeal spasm, poor airway, depression of bronchial secretions, and inability to turn over frequently are the causes of pneumonia and pulmonary atelectasis.
3, acidosis: respiratory acidosis due to poor breathing and inadequate gas exchange. Strong muscle contraction and incomplete decomposition of body fat after fasting increase acidic metabolites, resulting in metabolic acidosis.
4, circulatory failure: due to hypoxia and poisoning, tachycardia can occur, and after too long, heart failure can form, and even shock or cardiac arrest can occur. These complications are often an important cause of patient death and should be strengthened to prevent and treat.
Diagnosis and differential diagnosis
According to the history of injury and clinical manifestations, the diagnosis can generally be made in time, but for patients with only certain prodromal symptoms, the diagnosis is more difficult, and it is necessary to be vigilant and closely observe the condition to avoid delaying the diagnosis.
Tetanus is differentiated from the following diseases.
1, septic meningitis, although there are “corneal inversion” and neck tonicity and other symptoms, but no paroxysmal spasms. Patients have severe headache, high fever, jet vomiting, etc., and sometimes confusion. Cerebrospinal fluid examination has increased pressure and increased white blood cell count.
2. Rabies with a history of bite by a rabid dog or cat is dominated by convulsions of the swallowing muscles. Pharyngeal muscle stress is increased, the patient hears the sound of water or sees water, the pharyngeal bone immediately spasms, severe pain, can not swallow drinking water, and a lot of saliva.
3, other such as temporomandibular arthritis, eclampsia, hysteria, etc.
Prevention
Tetanus can be prevented, and the most reliable prevention method is the injection of tetanus toxoid. Through the injection of toxoid, the human body produces antibodies and maintains a certain concentration for a longer period of time, which can neutralize the tetanus toxin that enters the body and does not cause the disease. Strengthening labor protection in industrial and agricultural production, avoiding trauma, popularizing the new method of birth delivery, and treating wounds correctly and timely are also important preventive measures.
1, automatic immunity application of toxoid injection, can make people get automatic immunity. In some areas of China, pertussis, diphtheria and tetanus vaccination has been widely implemented among children. The “basic injection” requires subcutaneous injection of toxoid three times: 0.5ml for the first time, and 1ml for the second time, with an interval of 4-6 weeks between the two injections. The next year, 1 ml is given as a “booster” injection. In this way, the concentration of antitoxin produced in the body can reach a protective level of 0.01 U/ml and can be maintained at this level for 5 to 10 years. Therefore, for those who have had autoimmunization within 10 years, only 0.5ml of toxoid injection is needed to prevent tetanus after injury; for those who have had autoimmunization for more than 10 years, only 0.5ml of toxoid injection is needed if the wound is not heavily contaminated; if the wound is heavily contaminated, 0.5ml of toxoid injection is needed 3 to 4 hours after the injection of 0.5ml of toxoid injection, and then other parts of the wound are injected. Intramuscular injection of human tetanus immunoglobulin 250-500 U, so that the antitoxin first neutralizes the toxin. The active immunity provoked by the toxoid can then play its preventive role before and after the antitoxin effect disappears.
2, correct treatment of wounds, timely and thorough debridement of all wounds should be debridement. For seriously contaminated wounds, especially war wounds, remove all necrotic and non-viable tissue, remove foreign bodies, cut open the dead cavity, open the wound, fully drainage, not sutured. If the delivery is found to be poorly disinfected, the umbilicus must be washed with 3% hydrogen peroxide solution and then disinfected with tincture of iodine.
3. Passive immunization is generally indicated for those who have not been injected with toxoid before and have one of the following conditions.
①Wounds with obvious contamination.
② fine and deep puncture wounds.
③Serious open injuries, such as open cranial injury, open fractures, and burns.
④wounds that are not cleared in time or treated improperly.
⑤ before surgery (e.g. foreign body removal) due to certain old trauma.
The passive immunization method now in use is the injection of tetanus antitoxin (TAT) refined from animal (bovine or equine) serum. It is a heterogeneous protein that is antigenic, causes allergic reactions, and does not remain in the body for long, starting to be removed by the body after 6 days. Therefore, this tetanus antitoxin is not yet ideal. The ideal product is human tetanus immunoglobulin, which has no allergic reaction and can stay in the body for 4-5 weeks after 1 injection, and the immune suburban energy is 10 times more than that of tetanus toxin. Its prophylactic dose is 250-500U, injected intramuscularly. Human tetanus immune protein source is less, the preparation is complicated, in the current situation can not be commonly used, the injection of tetanus antitoxin is still not lost as a major passive immunization method.
Intramuscular injection of tetanus antibiotic 1500 IU (1ml) as early as possible after the injury. The dose may be doubled in cases of severe wound contamination or if the injury has been present for more than 12 hours. The dose for adults is the same as for children. If necessary, another injection can be given 2 to 3 days later.
Before each injection of antitoxin, ask if there is a history of allergy and make an intradermal allergy test: use 0.1 ml of antitoxin, add isotonic saline to dilute into 1 ml. inject 0.1 ml of the diluted solution intradermally in the flexor surface of the forearm; on the other hand, in the same part of the opposite forearm, with equal flushing and slightly elevated hard mass, it is positive and should be injected by desensitization method. However, this method does not completely avoid the occurrence of allergic reactions, so it is best not to use this antitoxin for injection. The desensitization method of injection is to dilute 1ml of antitoxin 10 times with isotonic salt, divide it into 1, 2, 3 and 4ml, and inject it subcutaneously once every half hour in sequence. After each injection, observe any reaction. If the patient has pale face, weakness, urticaria or painful itchy skin, sneezing, coughing, joint pain or even shock, ephedrine 50mg or epinephrine 1mg (adult dose) should be injected subcutaneously immediately and antitoxin injection should be stopped.