Coma is a life–threatening condition of impaired consciousness caused by damage to special structures of the brain and characterized by a complete lack of contact of the patient with the outside world. The causes of its occurrence can be divided into metabolic (poisoning by metabolic products or chemical compounds) and organic (in which the destruction of brain areas occurs). The main symptoms are unconsciousness and lack of eye opening reactions even to strong stimuli. CT and MRI, as well as laboratory blood test, play an important role in the diagnosis of coma. Treatment primarily involves combating the main cause of the development of the pathological process.
ICD 10
R40 Somnolence, stupor and coma
General information
Coma is one of the types of disorders of consciousness in which the patient completely lacks contact with the outside world and mental activity. This condition is so deep that the patient cannot be brought out of it even with the help of intensive stimulation.
In a comatose state, the patient always lies with his eyes closed and does not open them to sound or pain. This is how coma differs from other types of disorders of consciousness. All other signs: the presence or absence of spontaneous movements, preserved or extinguished reflexes, the ability to breathe independently or complete attachment to a life support device – depend solely on the reason why the patient fell into a comatose state and the degree of depression of the nervous system.
Not all, even very extensive, traumatic brain lesions can cause coma. For its occurrence, it is necessary to damage special areas that are responsible for wakefulness, no wonder in translation from ancient Greek coma is translated as “deep sleep”.
Causes
Coma is not an independent disease, it is a severe complication on the part of the central nervous system, which is based on damage to the nerve pathways. The cerebral cortex perceives signals about the surrounding world not directly, but through the reticular formation. It passes through the entire brain and is a filter that systematizes and passes through nerve impulses. If the cells of the reticular formation are damaged, the higher part of the brain loses contact with the outside world. A person falls into a state, which is called a coma.
Nerve fibers of the reticular formation can be damaged both directly by physical means and due to exposure to various chemicals:
- Physical damage. It can occur with conditions such as a brain stroke, trauma (bullet wound, bruise, hemorrhage).
- Chemical compounds that lead to damage to the nerve cells of the reticular formation are divided into 2 types:
Internal, which are products of metabolism and are formed as a result of diseases of internal organs. Internal damaging factors are: reduced oxygen content in the blood (hypoxia), high or low glucose and acetone bodies (in diabetes mellitus), ammonia (in severe liver diseases).
External, which enter the body from the outside. External intoxication of the nervous system can occur with an overdose of narcotic drugs, sleeping pills, poisoning with neurotropic poisons, exposure to bacterial toxins in infectious diseases.
A special damaging factor that combines signs of physical and chemical damage to the reticular formation is an increase in intracranial pressure. It occurs with traumatic brain injury, tumors of the central nervous system.
Classification
Who can be classified according to 2 groups of criteria: 1) depending on the reason that caused it; 2) according to the level of oppression of consciousness. Depending on the causes of coma , they are divided into the following types:
- traumatic (with traumatic brain injuries)
- epileptic (complication of epileptic status)
- apoplexy (the result of a stroke of the brain), meningial (develops as a consequence of meningitis)
- tumor (volumetric formations of the brain and skull)
- endocrine (with a decrease in thyroid function, diabetes mellitus)
- toxic (with renal and hepatic insufficiency).
However, this separation is not often used in neurology, as it does not reflect the true condition of the patient. The classification of coma according to the severity of the violation of consciousness – the Glazko scale – has become more widespread. Based on it, it is easy to determine the severity of the patient’s condition, build a scheme of urgent medical measures and predict the outcome of the disease. The Glazko scale is based on a cumulative assessment of three indicators of the patient: speech, the presence of movements, eye opening. Points are awarded depending on the degree of their violation. According to their sum, the level of consciousness of the patient is estimated: 15 – clear consciousness; 14-13 – moderate stun; 12-10 – deep stun; 9-8 – sopor; 7 and less – comatose state.
According to another classification, which is used mainly by resuscitators, coma is divided into 5 degrees:
- Precoma
- Coma I
- Coma II (sopor)
- Coma III (atonic)
- Coma IV (transcendental).
Symptoms
As already noted, the most important symptoms of coma, which are characteristic of any type of coma, are: complete lack of contact of the patient with the outside world and lack of mental activity. The remaining clinical manifestations will differ depending on the cause that caused the brain damage.
Body temperature. Coma caused by overheating is characterized by high body temperature up to 42-43 ° C and dry skin. Poisoning with alcohol and sleeping pills, on the contrary, is accompanied by hypothermia (body temperature 32-34 C⁰).
Respiratory rate. Slow breathing occurs in a coma from hypothyroidism (low thyroid hormone levels), poisoning with sleeping pills or drugs from the morphine group. Deep breathing movements are characteristic of a comatose state against the background of bacterial intoxication in severe pneumonia, as well as for brain tumors and acidosis caused by uncontrolled diabetes mellitus or kidney failure.
Blood pressure and heart rate. Bradycardia (a decrease in the number of heartbeats per minute) indicates a coma that has arisen against the background of acute heart pathology, and the combination of tachycardia (an increase in the number of heartbeats) with high blood pressure indicates an increase in intracranial pressure.
Arterial hypertension is characteristic of patients in a coma that has arisen on the background of a stroke. And low blood pressure occurs in diabetic coma, poisoning with sleeping pills, massive internal bleeding, myocardial infarction.
The color of the skin. Cherry-red skin color develops with carbon monoxide poisoning. Blueness of the fingertips and nasolabial triangle indicates a low oxygen content in the blood (for example, in case of suffocation). Bruises, bleeding from the ears and nose, bruises in the form of glasses around the eyes are characteristic of a coma that has developed against the background of a traumatic brain injury. Pronounced pale skin covers indicate a comatose state due to massive blood loss.
Contact with others. With sopor and mild coma, involuntary vocalizations are possible – the production of various sounds by patients, this serves as a favorable prognostic sign. As the comatose state deepens, the ability to pronounce sounds disappears.
Grimaces, reflex jerking of the hand in response to pain are characteristic of a mild coma.
Diagnostics
When diagnosing a coma, a neurologist solves 2 tasks simultaneously: 1) finding out the cause that led to the comatose state; 2) direct diagnosis of coma and its differentiation from other similar conditions.
Interviewing the patient’s relatives or bystanders helps to find out the causes of the patient falling into a coma. At the same time, it is specified whether the patient had previous complaints, chronic diseases of the heart, blood vessels, and endocrine organs. Witnesses are being questioned about whether the patient used medications, whether empty blisters or jars of drugs were found next to him.
The rate of development of symptoms and the age of the patient is important. A coma that has arisen in young people against the background of full health, most often indicates poisoning with narcotic drugs, sleeping pills. And elderly patients with concomitant diseases of the heart and blood vessels are likely to develop a coma on the background of a stroke or heart attack.
The examination helps to establish the suspected cause of the coma. The level of blood pressure, pulse rate, respiratory movements, characteristic bruises, bad breath, traces of injections, body temperature – these are the signs that help the doctor to make the correct diagnosis.
Particular attention should be paid to the patient’s position. An upturned head with an increased tone of the neck muscles indicates irritation of the membranes of the brain, which occurs with hemorrhages, meningitis. Convulsions of the whole body or individual muscles may occur if the cause of the coma was an epileptic status, eclampsia (in pregnant women). Sluggish paralysis of the limbs indicates a stroke of the brain, and the complete absence of reflexes indicates deep damage to the large surface of the cortex and spinal cord.
The most important thing in the differential diagnosis of coma from other states of impaired consciousness is the study of the patient’s ability to open his eyes to sound and pain irritation. If the reaction to sound and pain manifests itself in the form of an arbitrary opening of the eyes, then this is not a coma. If the patient does not open his eyes despite all the efforts of doctors, then the condition is considered comatose.
The reaction of the pupils to light is subjected to careful study. Its features not only help to establish the estimated location of the lesion in the brain, but also indirectly indicate the cause of the comatose state. In addition, the pupillary reflex serves as a reliable prognostic sign.
Narrow pupils (pupils-dots) that do not react to light are characteristic of poisoning with alcohol and narcotic substances. The different diameter of the pupils on the left and right eye indicates an increase in intracranial pressure. Wide pupils are a sign of damage to the midbrain. The dilation of the diameter of the pupils of both eyes, combined with the complete absence of their reaction to light, is characteristic of an exorbitant coma and is an extremely unfavorable sign indicating an imminent brain death.
Modern technologies in medicine have made instrumental diagnosis of the causes of a comatose state one of the very first procedures for admission of any patient with impaired consciousness. Performing computed tomography (CT of the brain) or MRI (magnetic resonance imaging) allows you to determine structural changes in the brain, the presence of volume formations, signs of increased intracranial pressure. Based on the images, a decision is made on the methods of treatment: conservative or urgent surgery.
If it is not possible to perform CT or MRI, the patient should be X-rayed of the skull and spinal column in several projections.
A biochemical blood test helps to confirm or refute the metabolic (metabolic failure) nature of the comatose state. The level of glucose, urea, and blood ammonia is being urgently determined. And also the ratio of blood gases and basic electrolytes (potassium, sodium, chlorine ions) is determined.
If CT and MRI results indicate that there are no reasons from the Central nervous system that can put the patient into a coma, a blood test is performed for hormones (insulin, adrenal hormones, thyroid gland), toxic substances (drugs, sleeping pills, antidepressants), bacterial blood culture. Electroencephalography (EEG) is the most important study that helps to differentiate the types of com. When it is carried out, the electrical potentials of the brain are recorded, the assessment of which makes it possible to distinguish a comatose state caused by a brain tumor, hemorrhage, or poisoning.
Treatment
Coma treatment should be carried out in 2 directions: 1) maintaining the vital functions of the patient and preventing brain death; 2) combating the main cause that caused the development of this condition.
Maintenance of vital functions begins already in the ambulance on the way to the hospital and is carried out to all patients in a coma even before receiving the results of the examination. It includes maintaining the patency of the respiratory tract (straightening the sunken tongue, cleansing the oral cavity and nasal cavity from vomit, oxygen mask, insertion of a breathing tube), normal blood circulation (administration of antiarrhythmic drugs, drugs normalizing pressure, closed heart massage). In the intensive care unit, if necessary, the patient is connected to a ventilator.
Anticonvulsant drugs are administered in the presence of seizures, mandatory intravenous glucose infusion, normalization of the patient’s body temperature (covering and covering with hot water bottles for hypothermia or fighting fever), gastric lavage in case of suspected poisoning with drugs.
The second stage of treatment is carried out after a detailed examination, and further medical tactics depend on the underlying cause that caused the coma. If it is an injury, brain tumor, intracranial hematoma, then urgent surgical intervention is performed. When a diabetic coma is detected, the level of sugar and insulin is taken under control. If the cause was renal failure, then hemodialysis is prescribed.
Forecast
The prognosis for coma depends entirely on the degree of damage to the brain structures and the causes that caused it. In the medical literature, the patient’s chances of coming out of a comatose state are regarded as: with precom, coma I – favorable, complete recovery without residual effects is possible; coma II and III – doubtful, that is, there is both a probability of recovery and a fatal outcome; coma IV – unfavorable, in most cases ends with the death of the patient.
Preventive measures are reduced to early diagnosis of the pathological process, the appointment of the correct methods of treatment and timely correction of conditions that can cause the development of coma.
