Loss of Consciousness
Alternate Names : Unconsciousness
Consciousness is the state of being aware of or responsive to the environment. A
person who is conscious can perceive, both physically and mentally, what is happening. For many reasons, a person can sometimes lose
consciousness, or become unconscious.
What is going on in the body?
An unconscious person generally seems to be sleeping.
However, being unconscious is different from being asleep. A person can
usually, but not always, be roused from the unconscious state.
What are the causes and risks of the condition?
There are many causes of unconsciousness, including:
fainting, which may occur in
healthy, normal people. It often results from fatigue, pain, injury, or strong emotions such as fear. It is
also common during pregnancy.
Someone who faints usually wakes up within 2 minutes. Most of the time, there
are no lasting problems associated with a fainting episode.
low blood pressure, also
called hypotension. This can occur for many reasons. High blood pressure
medications, serious blood loss, and
dehydration are all possible causes. Orthostatic hypotension, a condition in which the blood
pressure drops quickly when the person stands up, can also cause fainting.
medication, drug, or toxin exposure. This can include overdose with alcohol, barbiturates, or narcotics.
head injury. This may be mild
in the case of a concussion, or more
serious, as in the case of a skull fracture.
stroke, also called brain
attack. This is brain damage that usually occurs due to a lack of oxygen. A
transient ischemic attack or TIA is
another cause of unconsciousness.
bleeding into or around the brain, which occurs with a subdural hematoma, epidural hematoma, or
subarachnoid hemorrhage
infections, such as the brain infections called meningitis and
encephalitis
low blood sugar levels, called
hypoglycemia
diabetes that is out of control
severe liver disease or kidney disease
seizures, or jerking movements
caused by abnormal electrical activity in the brain
low oxygen level in the blood, which can occur with severe lung or heart disease. For example, severe asthma, emphysema, irregular heartbeats called arrhythmias, severe
congestive heart failure, or a blood clot in the lung, called a pulmonary embolus, can all cause low
oxygen levels in the blood.
abnormally low body temperature, also called hypothermia
severe salt imbalances, such
as abnormally low or high sodium levels in the blood
brain tumors
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