Stupor and Coma - Brain, Spinal Cord, and Nerve Disorders - Merck ...

Stupor is unresponsiveness from which a person can be aroused only by vigorous, physical stimulation. Coma is unresponsiveness from which a person cannot be aroused and in which the person's eyes remain closed, even when the person is stimulated.
Stupor and coma are usually caused by a disorder, a drug, or an injury that affects large areas on both sides of the brain or specialized areas of the brain involved in maintaining consciousness.
A physical examination, blood tests, brain imaging, and information from family and friends help doctors identify the cause.
Doctors correct causes if possible, and take measures to support breathing and other body functions (such as mechanical ventilation) and to reduce pressure within the skull if it is increased.
Recovery from coma depends largely on the cause.
Control of consciousness
Normally, the brain can quickly adjust its own levels of activity and consciousness as needed. The brain makes these adjustments based on information it receives from the eyes, ears, skin, and other sensory organs. For example, the brain can adjust its metabolic activity (energy level) and induce sleep.
The brain’s ability to adjust its activity and consciousness levels is impaired when
Both cerebral hemispheres malfunction, particularly when they are suddenly and severely damaged.
The reticular activating system malfunctions.
The brain’s ability to adjust its activity and consciousness levels is also impaired in the following situations:
When people are severely deprived of sleep
When and immediately after a seizure occurs
When blood flow or the amount of nutrients (such as oxygen or sugar) going to the entire brain decreases
When blood flow going to certain parts of the brain decreases, as occurs in certain strokes
When toxic substances damage nerve cells in the brain or make them function less well
When bleeding or swelling due to brain tumors or injury puts pressure on parts of the brain
Toxic substances may be taken into the body (for example, by consuming or inhaling them). Or they may be produced in the body as a waste product of normal processes but are not broken down and removed as they normally are.
Viewing the Brain
The brain consists of the cerebrum, brain stem, and cerebellum. Each half (hemisphere) of the cerebrum is divided into lobes.
Levels of impaired consciousness
Periods of impaired consciousness can be short or long. The degree of impairment can range from slight to severe. Doctors use various terms to describe the different levels of consciousness:
Lethargy is a slight reduction in alertness or mild mental fogginess (clouding of consciousness). People tend to be less aware of what is happening around them and to think more slowly than usual. They may feel tired and lack energy.
Obtundation, an imprecise term, refers to a moderate reduction in alertness or moderate clouding of consciousness.
Altered mental status, a very imprecise term, is sometimes used by doctors to refer to a change in consciousness, such as lethargy, obtundation, delirium, or sometimes stupor or coma.
Stupor is an excessively deep state of unresponsiveness. People can be aroused from it only briefly by vigorous stimulation, such as repeated shaking, loud calling, or pinching.
Coma is a state of complete unresponsiveness (except for certain automatic reflexes). People cannot be aroused at all. Their eyes stay closed. People in a deep coma lack purposeful responses, such as moving a limb away from something that hurts.
Causes of Stupor and Coma
The various levels of impaired consciousness—lethargy, obtundation, stupor, and coma—have the same causes, of which there are many.
Blood delivers oxygen and essential nutrients (such as fats, sugars, minerals, and vitamins) to the body's tissues. Thus, when blood flow to the brain is decreased, the brain is deprived of oxygen and essential nutrients. The brain may also be deprived of oxygen when the lungs are not functioning normally, as occurs in respiratory failure. The brain can be deprived of nutrients when a disorder (such as hypoglycemia) causes levels of nutrients in the blood to be low.
Any disorder that increases pressure within the skull (intracranial pressure) can impair consciousness. A mass in the brain, such as an accumulation of blood (hematoma), a tumor, or an abscess, can impair consciousness indirectly by putting pressure on the areas of the brain that control consciousness.
A structural abnormality can block the flow of cerebrospinal fluid in the brain, increasing pressure within the skull. Cerebrospinal fluid is the fluid that flows through the tissues covering the brain and spinal cord and fills the spaces within the brain. Some structural abnormalities are present at birth.
A large mass can push the brain against the relatively rigid structures inside the skull, damaging brain tissue. If the areas of the brain that control consciousness are affected, stupor or coma results. If the pressure is high enough, the brain may be forced through a small natural opening in the relatively rigid sheets of tissue that separate the brain into compartments. This life-threatening disorder is called brain herniation Herniation: The Brain Under Pressure . Herniation can further damage brain tissue, making an already dire condition worse.
Having had a stroke or having another disorder that affects brain function makes the brain more susceptible to other disorders that can impair consciousness.
Psychiatric disorders and stress
Occasionally, people who have a psychiatric disorder or those who are psychologically stressed may appear unresponsive. For example, people who learn that they have cancer or that their spouse is going to leave them may collapse and not respond when they are spoken to or touched. Yet, such people may be aware of what is happening around them, and their brain may be functioning normally.
Development of a new disorder (such as stroke or heart failure) or worsening of a disorder they already have
Table
Symptoms of Stupor and Coma
Consciousness is impaired to varying degrees. People in a stupor are usually unconscious but can be aroused with vigorous stimulation. People in a coma are unconscious, with their eyes closed, and they cannot be aroused.
The brain damage or dysfunction that causes stupor and coma affects other parts of the body.
The pattern of breathing is usually abnormal. People may breathe too rapidly, too slowly, too deeply, or irregularly. Or they may alternate between these abnormal patterns.
Blood pressure may increase or decrease, depending on the cause of the impaired consciousness. For example, if a head injury causes massive bleeding in the brain, pressure within the skull rapidly increases, and blood flow to the brain decreases. The nerves that control blood pressure respond by increasing blood pressure to try to maintain normal blood flow to the brain. If the cause of impaired consciousness is a severe infection, severe dehydration, major blood loss, overdoses of certain drugs, or cardiac arrest, blood pressure decreases dramatically.
Muscles may contract and remain contracted in unusual positions. For example, the head may be tilted back with the arms and legs extended—a position called decerebrate rigidity. Or the arms may be flexed with both legs extended—a position called decorticate rigidity. Or the entire body may be limp. Sometimes muscles contract sporadically or involuntarily.
The eyes may be affected. One or both pupils of the eyes may be widened (dilated) and may not react to changes in light. Or the pupils may be tiny. The eyes may not move or may move in abnormal ways.
The disorder that is impairing consciousness may cause other symptoms. For example, if the cause is meningitis (infection of the layers of tissue covering the brain and spinal cord), early symptoms may include fever, vomiting, headache, and a painful, stiff neck that makes lowering the chin to the chest difficult or impossible.
Diagnosis of Stupor and Coma
Doctors can tell that consciousness is impaired based on observation and examination. Doctors try to identify the parts of the brain that are impaired and the cause of impairment because treatment differs and because impairment may progress, leading to coma and brain death.
Stupor is diagnosed when vigorous, repeated attempts arouse the person only briefly. Coma is diagnosed when the person cannot be aroused at all and the eyes remain closed.
People who become stuporous or comatose must be taken to the hospital immediately because either state may be caused by a life-threatening disorder. Health care practitioners try to identify the cause and provide emergency medical care at the same time. For example, a quick test is done to estimate the blood sugar level. Then if people have a low blood sugar level (which can quickly and permanently damage the brain), it can be treated immediately.
A stuporous or comatose person cannot communicate. So the doctor usually checks whether the person is wearing a medical alert identification bracelet or necklace, which may suggest the cause. The doctor may check the person's wallet, purse, or pockets for medical identification (such as a hospital identification card) or drugs, which may also help identify the cause. Thus, a person with a disorder that increases the risk of stupor or coma (such as diabetes or a seizure disorder) should carry or wear some form of medical identification.
The doctor asks any witnesses of the change in consciousness about the circumstances in which it occurred and any other symptoms the person had. For example, if the person's limbs jerked repeatedly when consciousness was affected, the cause may have been a seizure. The doctor also talks to family members and friends, who should honestly provide emergency medical personnel or the doctor with any relevant information about the person, which includes the following:
Whether the person uses drugs (prescription and recreational), alcohol, or other toxic substances and which ones are used
Whether the person was injured before the change in consciousness
When and how the problem began
Whether the person has or has had any infections, other disorders (such as diabetes, high blood pressure, a seizure, or a thyroid, kidney, or liver disorder), or other symptoms (such as headaches or vomiting)
When the person last seemed normal
Whether the person had eaten any unusual foods or been traveling
Whether they have any hunches about what might be the cause (for example, if the person was recently depressed or talked about suicide)
This information can help doctors identify possible causes and helps them assess how likely the person is to recover. Many such causes would not be identified, even with extensive diagnostic testing, if this information was unavailable. For example, if people have eaten unusual foods, the cause may be a toxin (such as those in poison mushrooms). If people have traveled recently, the cause may be an infection that is common in the area they visited. If empty pill containers or drug paraphernalia were found nearby, the cause may be a drug overdose. If a drug or toxic substance was ingested, family members or friends should give a sample of that substance or its container to the doctor.
Did You Know...
Information from friends and family members is often more helpful in determining the cause of coma than diagnostic tests.
Information from the family and friends is usually valuable and is more likely to lead to the correct diagnosis than examination or testing. For example, no test can rule out all possible drug overdoses.
Physical examination
Body temperature is checked. An abnormally high temperature may indicate infection, heatstroke, or an overdose of a drug that stimulates the body (such as cocaine or an amphetamine). An abnormally low temperature may indicate prolonged exposure to cold, an underactive thyroid gland, alcohol intoxication, a sedative overdose or, in older people, infection.
Doctors examine the head, face, and skin for clues to the cause, such as the following:
Black eyes, cuts, bruises, or leakage of cerebrospinal fluid (the fluid that surrounds the brain) from the nose or ears suggests a head injury.
Needle marks suggest an overdose of a drug, such as heroin.
Fever with a rash often suggests an infection, such as sepsis (a serious bodywide response to a bloodstream infection) or a brain infection.
If people are unconscious, doctors try to rouse them first by speaking to them, then by touching their limbs, chest, or back. If these measure do not work, doctors use stimuli that cause discomfort or pain, such as pressure on a nail bed or a pinch. If people open their eyes or grimace when a painful stimulus is applied or if they purposefully withdraw from it, consciousness is not severely impaired. If people can make sounds, the cerebral hemispheres are functioning to some degree. If the eyes open, some parts of the brain stem are probably functioning.
Doctors sometimes use a standardized scoring system, such as the Glasgow Coma Scale, to help track changes in a person's level of consciousness. This scale assigns points based on responses to stimuli. Eye movement, speech, and movements are evaluated. This scale is a relatively reliable, objective measure of how unresponsive people are.
Abnormal breathing patterns can provide clues to which parts of the brain are malfunctioning.
Checking responses to painful stimulation can help determine whether parts of the brain and spinal cord are malfunctioning. When coma is present, using painful stimuli may trigger unusual body positions. For example, the head may be tilted back with the arms and legs extended (called decerebrate rigidity). Or the arms may be flexed with both legs extended (called decorticate rigidity). This test helps identify the area of the brain that is not functioning normally.
Limpness of the entire body and no movements in response to pain are the worst possible response. They indicate severe dysfunction in the central nervous system (brain and spinal cord). However, if muscle tone and movements return, the cause may be a reversible one, such as a sedative overdose.
All automatic reflexes are normal if unresponsiveness is caused by a psychiatric disorder that does not impair consciousness.
The eyes also provide important clues about how well the brain stem is functioning and what may be impairing consciousness. Doctors check the position of the pupils, their size, their reaction to bright light, their ability to follow a moving object (in people who are alert and awake), and the appearance of the retina. Normally, pupils widen (dilate) when light is dim and become smaller (constrict) when light is shined on them. However, the pupils may not respond normally to light in people in a coma. How the pupils respond to light or whether they respond helps doctors determine the cause of the coma.
To accurately evaluate the person, doctors need to know whether the person takes a drug to treat glaucoma, which can affect pupil size, and they usually need to know whether the person’s pupils are normally different sizes.
If findings suggest that the pressure within the skull is increased, doctors do imaging tests immediately to check for swelling, bleeding, a structural abnormality that blocks the flow of cerebrospinal fluid, or a mass in the brain (such as a tumor, an accumulation of blood, or an abscess). If imaging test results indicate increased pressure, doctors may drill a small hole in the skull and insert a device into one of the fluid-filled spaces (ventricles) in the brain. This device is used to reduce the pressure and monitor it during treatment.
The person’s response to certain maneuvers can help doctors determine whether the brain stem is functioning normally:
Rotating the head and observing eye movements.
If the person is unconscious, gently flushing ice-cold water into one ear, then the other ear and observing eye movements (called caloric testing)
Laboratory tests
These tests provide further clues about the possible cause of stupor or coma.
Blood levels of substances including sugar, electrolytes (such as sodium), alcohol, oxygen, minerals (such as magnesium), and carbon dioxide are measured. High levels of carbon dioxide may indicate that the person's breathing is impaired and that mechanical ventilation is required. Red and white blood cell counts are determined. Blood tests to check liver function and kidney function are done.
Urine is analyzed to determine whether any commonly used or suspected toxic substances are present. Samples of blood and urine may be sent to a laboratory to be cultured (to grow any microorganisms present) to check for infections.
Doctors measure the oxygen level in blood with a sensor placed on a finger (called pulse oximetry). They also measure levels of oxygen, carbon dioxide, and sometimes other gases in a sample of blood withdrawn from an artery (arterial blood gas tests). These tests are done to check for heart and lung disorders.
Other laboratory tests may be done, depending on which causes of coma doctors suspect.
Other tests
Electrocardiography (ECG) is done to check for heart disorders, which may reduce blood flow to the brain. Chest x-ray may be done to check for lung disorders, which may reduce the amount of oxygen in the blood.
If no cause has been quickly identified, computed tomography (CT) or magnetic resonance imaging (MRI) of the head is done to check for a mass, bleeding, swelling, or other structural brain damage.
Prognosis for Stupor and Coma
In general, if people with impaired consciousness start to respond to sounds, touch, or other stimuli within 6 hours, they are more likely to recover. Recovery is also likely if one or more of the following occur within the first days:
Speech returns, even if it is incomprehensible.
The eyes can follow an object.
People can follow commands.
Muscle tone returns to normal.
The likelihood of recovery also depends on the cause and duration of impaired consciousness, as in the following:
Overdose of a sedative: Recovery is likely unless people stopped breathing long enough to cause brain damage.
A low blood sugar level: Complete recovery is possible if the brain was not deprived of sugar for more than about 1 hour.
Head injury: Substantial recovery may occur, even if the coma lasts several weeks (but not if it lasts more than 3 months).
Seizures that occur within 24 to 48 hours after cardiac arrest and that recur repeatedly
If people cannot move their limbs after cardiac arrest, recovery is difficult.
However, if doctors have used cooling to treat people after cardiac arrest, they usually wait an extra 3 days for these responses to occur. Cooling the body may preserve brain function after cardiac arrest, but it also tends to slow recovery of brain function.
Treatment of Stupor and Coma
Measures to help people breathe and to improve blood flow to the brain
Treatment of the cause
Immediate treatment
If a person is rapidly becoming less alert and more difficult to arouse, immediate treatment is required, often before a diagnosis is made. This rapid deterioration in consciousness is considered a medical emergency.
The first steps in treatment, sometimes done by emergency medical personnel, are to check
People are treated first in an emergency department and then admitted to a hospital intensive care unit. In both places, nurses can monitor heart rate, blood pressure, temperature, and the oxygen level in the blood. Any abnormalities in these measurements are immediately corrected to prevent further damage to the brain. Oxygen is often given immediately, and a tube is inserted into a vein (an intravenous line) so that drugs or sugar (glucose) can be given quickly.
Blood pressure is closely monitored to make sure it is not too high or too low. High blood pressure can further impair consciousness and lead to other problems, such as stroke. Low blood pressure can impair consciousness because the brain does not get enough blood and oxygen.
If a head injury is the cause, the neck must be immobilized until doctors can check for damage to the spine. Some people in a stupor or coma after a head injury benefit from treatment with drugs that can help nerve cells function better, such as amantadine. Such treatment may help people regain some level of function more quickly. However, such treatment may not make any difference in improvement over the long term.
If opioid overdose is suspected, the antidote naloxone is given. Recovery may be almost immediate if the opioid is the only cause of impaired consciousness. If people take opioids, their doctor may prescribe a naloxone auto-injector for them. This device enables a family member or other caregiver to give them naloxone immediately if an opioid overdose is suspected.
Rarely, when a person may have ingested certain toxic substances or drugs within about 1 hour, doctors may insert a large tube through the person's mouth and into the stomach so that the stomach can be pumped. Pumping the stomach is done to identify its contents and to prevent more of the substances from being absorbed. Activated charcoal may also be given through the tube or through a smaller tube inserted through the nose (nasogastric tube). The charcoal prevents the stomach from absorbing more of the substances.
The breathing tube is inserted through the mouth and into the windpipe (trachea)—called endotracheal intubation. Oxygen is delivered directly into the lungs through the tube. The tube also prevents people from inhaling stomach contents after vomiting. Before inserting the tube, doctors may spray the person's throat with a numbing spray or give the person a drug to prevent the muscles from contracting involuntarily (a paralytic drug). The tube is then attached to a mechanical ventilator.
Mechanical ventilation can cause agitation, which can be treated with a sedative.
Treatment of increased pressure within the skull
If the pressure within the skull (intracranial pressure) is increased, the following measures may be taken to lower it:
The head of the bed may be elevated.
Mechanical ventilation may be used to help people breathe faster (called hyperventilation), particularly during the first half hour it is used. Breathing faster removes carbon dioxide from the lungs and reduces the level of carbon dioxide in the blood. As a result, blood vessels in the undamaged part of the brain narrow, and less blood reaches the brain. This measure quickly but temporarily lowers pressure within the skull (for about 30 minutes) and does not damage the brain further. Lowering the pressure for a time gives doctors time to start to treat the cause—for example, to do emergency brain surgery.
Diuretics or other drugs may be used to reduce fluids in the brain and rest of the body. Diuretics help eliminate excess fluid by causing the kidneys to excrete more sodium and water into urine.
A sedative may be given to control excess involuntary muscle contractions or agitation caused by mechanical ventilation. These problems can increase pressure within the skull.
Blood pressure is lowered if it is very high.
Sometimes doctors insert a drain (shunt) into the ventricles of the brain to drain cerebrospinal fluid. Removing excess fluid can help lower pressure within the skull.
If pressure is increased because of a brain tumor or abscess, corticosteroids, such as dexamethasone, may help reduce pressure. However, corticosteroids are not used when increased pressure is caused by certain other disorders, such as intracerebral hemorrhage or a stroke, because corticosteroids may make these conditions worse.
If other measures do not work, the following may be tried:
When pressure within the skull is increased after a head injury or cardiac arrest, measures to lower body temperature may be tried. These measures may help some people who have had cardiac arrest. However, use of this measure is controversial.
Pentobarbital (a barbiturate) may be used to reduce blood flow to the brain and brain activity. This treatment may improve the prognosis for some people. However, it is not beneficial for everyone, and it has side effects, such as low blood pressure and abnormal heart rhythms.
The skull may be opened surgically (craniectomy), creating more room for the swollen brain and thus reducing pressure on the brain. This treatment can prevent death, but it may not improve a person's ability to function.
Damage to muscles and nerves in the arms and legs: Lack of movement or lying in one position for a long time can put pressure on a nerve that runs close to the surface of the body near a prominent bone, such as a nerve in an elbow, a shoulder, a wrist, or a knee. Such pressure can injure the nerve. As a result, the muscles that the nerve controls function less well.
Pressure sores can be prevented by frequently repositioning the person and placing protective padding under parts of the body that are in contact with the bed, such as the heels, to protect them.
To prevent contractures, physical therapists gently move the person’s joints in all directions (passive range-of-motion exercises) or splint joints in certain positions. Starting physical therapy early can help people who have not been able to move recover function.
Preventing blood clots includes use of drugs and compression or elevation of the person's legs. Moving the limbs, as occurs in passive-range-of-motion exercises, may also help prevent blood clots.
Because people cannot blink, their eyes may become dry. Eye drops can help.
If people are incontinent, care should be taken to keep the skin clean and dry. If the bladder is not functioning and urine is being retained, a tube (catheter) may be placed in the bladder to drain urine. Catheters are carefully cleaned and regularly examined to prevent urinary tract infections from developing.
Essentials for Older People: Coma and Stupor
Impaired consciousness, including lethargy, stupor, and coma, is a particular concern among older people for the following reasons:
A complex drug schedule: Also, if older people have to take many drugs, the schedule for taking them may be complex. As a result, they are more likely to make mistakes and may take too much or too little of a drug.
Effect of minor disorders: Relatively minor disorders, such as a urinary tract infection or dehydration, are more likely to impair consciousness in older people than in younger people.
Presence of other disorders: Many disorders that are more common among older people can impair consciousness. They include strokes, brain tumors, bulges in weakened arteries (aneurysms) in the brain, metabolic disorders, severe lung disorders, severe infections, and heart failure. Other disorders (such as diabetes) increase the risk of impaired consciousness if another problem (such as dehydration or an infection) develops.
Lifetime exposure to toxins: Over a lifetime, exposure to toxins in foods and the environment can damage brain cells and increase the risk of consciousness becoming impaired.
Difficulty recognizing impaired consciousness: Impaired consciousness may be harder to recognize in older people. If older people become less alert or less conscious of things around them, family members and friends may not notice or may assume that the change results from aging. (Impaired consciousness is not a normal part of aging.) Also, a change in consciousness may be harder to discern in older people who have dementia or another brain disorder or who have had a stroke.
Ability to recover: Older people are less likely to recover from stupor or coma because the brain becomes less able to repair itself as people age.
In older people, consciousness is commonly impaired by reactions to drugs, dehydration, and infections.
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