Coma, from the Greek word "koma," meaning deep sleep, is a state of extreme unresponsiveness, in which an individual exhibits no voluntary move...
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What Is a Coma?
A coma is a prolonged state of unconsciousness. A coma
occurs when a part of the brain is damaged, either temporarily or permanently.
This damage results in unconsciousness, an inability to awake, and
unresponsiveness to stimuli such as pain, sound, and light. The word “coma” is
derived from the Greek word “koma,” which means “deep sleep” (Koehler &
Comas may be caused by an injury, an illness, a stroke,
tumors, drugs, alcohol abuse, and other damage to the brain. A person who is in
a coma is alive but is unable to move at will, think, speak, or respond to his
or her environment. Important functions, such as breathing and blood
circulation, remain intact.
A coma is a medical emergency. Doctors need to work quickly
to preserve brain life and function, and to keep the patient healthy during the
course of his or her coma. A coma may be challenging to diagnose and treat. A
coma usually does not last for more than four weeks, and recovery occurs
gradually. However, some patients have remained in comas for years or even
What Causes a Coma?
Comas are caused by damage to the brain—specifically, either
the diffused bilateral cerebral
hemisphere cortex or the reticular
activating system, which controls
arousal and awareness (Adukauskiene
et al, 2008). Comas can be caused by many factors, including head injuries,
loss of oxygen, bleeding or pressure in the brain, infections, metabolic problems,
and toxic factors. Some examples include:
- traumatic brain injuries, such as those caused
by traffic accidents or violent fights
- stroke (reduced blood supply to the brain)
- tumors in the brain or brainstem
- lack of oxygen to the brain, such as when the patient
is rescued from drowning or from a heart attack
- diabetes, when blood sugar levels become too
high (hyperglycemia) or too low (hypoglycemia), which can lead to swelling in
- overdosing on drugs or alcohol
- carbon monoxide poisoning
- buildup of toxins in the body, such as ammonia,
urea, or carbon dioxide
- lead poisoning
- infections such as meningitis or encephalitis
- repeated seizures
- electrolyte imbalance
What Are the Symptoms of a Coma
A coma is a medical emergency and requires immediate medical
attention. Signs of a coma include:
- closed eyes
- irregular breathing
- no response of limbs, except for reflexes
- no response to pain, except for reflexes
- pupils not responding to light
How Is a Coma Diagnosed?
People in a coma cannot speak or express themselves in other
ways. Doctors must rely on information from loved ones or witnesses, and on any
physical signs that may give information about what caused the coma.
A doctor will ask friends and family about any events or
symptoms that led up to the coma, details about recent changes in the patient’s
life, medical history, and drug-use, including prescription drugs and
over-the-counter drugs, as well as recreational drugs.
A doctor will then conduct a physical exam. This might
for signs of bruises on the skin that may have been caused by trauma
the patient’s response to painful stimuli
Blood tests and other laboratory tests will be used to test
for the following:
and liver function
of the nervous system
Doctors may order tests that create images of the brain (brain
scans), to locate areas of brain injury and look for signs of brain hemorrhage,
tumors, strokes and seizures. These tests include:
tomography (CT) scans, which use X-rays to create a detailed image of the
- magnetic resonance
imaging (MRI), which uses radio waves and magnets to view the brain; and
(EEG), which measures electrical activity inside the brain
How Is a Coma Treated?
Doctors will work first to preserve brain life and function.
Antibiotics may be given right away, in case there is an infection in the
brain. If the cause of the coma is known, such as in the case of a drug
overdose, doctors will administer proper medications to treat the underlying
condition. Surgery may be required to reduce swelling in the brain.
Once the patient stabilizes, a team of medical professionals
will work with the comatose patient to prevent infections, bedsores, and
contractures of the muscles. The team will also make sure to provide the
patient with balanced nutrition during his or her coma.
What Can Be Expected Long-Term?
A coma usually does not last for more than four weeks.
However, some people may remain in a coma for years. Long-term outcomes depend
on what caused the coma and the site of damage to the brain. Prognosis is good
for people whose comas are caused by a drug overdose. If the patient has
suffered severe brain damage, he or she may never come out of the coma.
Some people emerge from a coma with physical,
intellectual, or psychological problems. Patients who remain in a coma for more
than a year are unlikely to come out of that state (Mayo, 2012). For these
people, the most common cause of death is infection (NIH, 2013).
Medically Reviewed by:
George Krucik, MD, MBA
Aug 27, 2013
Published By: Healthline Networks, Inc.