View Full Version : Coma

04-14-2004, 07:33
The clinical definition of coma is: An abnormally deep state of unconsciousness from which the patient cannot be aroused by external stimuli.

What are the 6 general causes of Coma and their clinical presentation?

04-14-2004, 13:05
Causes of Coma: from the Merck Manual...since I had to look it up.

Stupor or coma can be caused by many disorders. A head injury can directly damage the areas of the brain stem that control consciousness levels or can cause bleeding (hemorrhage) in or around the brain. Blood can also directly damage these areas of the brain stem, or an accumulation of blood (hematoma) can put pressure on these areas. Brain tumors or collections of pus (abscesses) can also put pressure on these areas.

Alcohol intoxication and overdose of certain drugs (such as sedatives --and opioids) are common causes of stupor or coma. Occasionally, the use of certain antipsychotic drugs results in an unresponsive state called neuroleptic malignant syndrome. Abnormally low or high levels of substances (including sugar and electrolytes such as sodium) in the blood can interfere with brain function and impair consciousness. Brain infections (such as encephalitis and meningitis) and severe infections outside the brain can lead to coma. In older people, toxic reactions to drugs, dehydration (which results in a high sodium level), and infections are common causes of stupor.

Other causes of stupor or coma include the sudden stopping of the heart's pumping (cardiac arrest), aneurysms, severe lung disorders, inhalation of carbon monoxide, stroke, seizures, an underactive thyroid gland (hypothyroidism), liver or kidney failure, and low or high body temperature (hypothermia or hyperthermia).

DX-Clinical Presentation-

person who becomes stuporous or comatose must be taken to the hospital immediately because either state may be caused by a life-threatening disorder. People with disorders that put them at risk of stupor or coma should carry medical identification or wear a Medic Alert identification bracelet or necklace. Thus, if they lose consciousness, medical personnel can quickly identify the probable cause.

Because a stuporous or comatose person cannot communicate, family members and friends must be honest with doctors about the person's use of drugs, alcohol, or other toxic substances. 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.

When emergency medical personnel or doctors examine a stuporous or comatose person, they first check whether the airway is open, whether breathing is adequate, and whether blood pressure and pulse are normal. Body temperature is checked: An abnormally high temperature may indicate infection; an abnormally low temperature may indicate prolonged exposure to cold, an underactive thyroid gland, alcohol intoxication, or, in older people, infection. The skin is examined for signs of injury, drug injections, and allergic reactions, and the scalp is examined for cuts and bruises. Doctors also perform as thorough a neurologic examination as is possible with a stuporous or comatose person.

Doctors look for signs of brain damage or impaired brain function. One sign of brain damage is Cheyne-Stokes respiration (periodic breathing), an unusual pattern in which a person breathes rapidly, then more slowly, then not at all for several seconds. Unusual postures may be signs of significant brain damage. Such postures include decerebrate rigidity, in which the head is tilted back and the arms and legs are extended, and decorticate rigidity, in which the arms are flexed. General limpness of the entire body is of even greater concern, indicating widespread loss of activity in all parts of the central nervous system, including the brain stem and the nerve fibers that connect the upper part of the brain (cerebrum) to the spinal cord.

The eyes also provide important clues. The position of the pupils, their size, their reaction to bright light, their ability to follow a moving object (in people who are not comatose), and the appearance of the retina are checked. A widened (dilated) pupil that does not react to bright light may indicate pressure on cranial nerve III, which helps control eye movement, or on the brain stem. Doctors need to know if the person's pupils are normally different sizes or if the person takes a drug to treat glaucoma, which can affect pupil size.

Laboratory procedures provide further clues about the possible cause of stupor or coma. Blood levels of substances such as sugar, sodium, alcohol, oxygen, and carbon dioxide are measured. The red and white blood cell counts are determined. Urine is analyzed to determine whether sugar or toxic substances are present.

Additional procedures include computed tomography (CT) or magnetic resonance imaging (MRI) of the head to rule out the possibility of structural brain damage, such as that due to bleeding (hemorrhage), a tumor, or an abscess. If meningitis is remotely possible, a spinal tap (lumbar puncture) is performed to withdraw and examine a sample of cerebrospinal fluid. Because a coma may also be due to a brain tumor or hemorrhage, emergency CT or MRI of the brain is often performed before the spinal tap to determine whether the increased pressure inside the skull has forced the brain downward in the skull. If the pressure is high enough, the brain may be forced through the small natural opening in the relatively rigid sheets of tissue that separate the brain into compartments. This life-threatening disorder is called brain herniation. Performing a spinal tap reduces the pressure below the brain and thus may trigger or worsen a herniation.

Hope that helps.

04-14-2004, 14:32
Good copy and paste job there ShadowFlyer but no.

Clinical presentations of the below is your homework.

Intracranial Bleeding
Head Trauma
Brain Tumor or other lesion

Metabolic System-
Diabetic Ketoacidosis
Thiamine Deficiency
Kidney or Liver Failure
Postictal Phase of Seizure


Cardiovascular System-
Hypertensive Encephalopathy