Encyclopedia of Health and Medicine

consciousness 245
there are no outward indications that a concussion
has occurred.
Because the potential for serious BRAIN
damage exists even with an apparently
minor concussion, a person who experiences
a blow to the head that results in
loss of CONSCIOUSNESS or symptoms of
concussion that last longer than 15 minutes
should undergo examination by a
physician.
The diagnostic path includes a basic NEUROLOGIC
EXAMINATION to assess the person’s level of CON-
SCIOUSNESS and REFLEX responses. The doctor may
conduct diagnostic imaging procedures such as
COMPUTED TOMOGRAPHY (CT) SCAN or MAGNETIC RESO-
NANCE IMAGING (MRI) to determine whether there is
active bleeding within the brain and to assess the
extent of damaged tissue when the concussion is
severe. The doctor may also conduct an ELECTROEN-
CEPHALOGRAM (EEG) to assess the brain’s electrical
activity.
grade 1
grade 2
grade 3
GRADING OF CONCUSSION
brief confusion but no loss of CONSCIOUSNESS
extended confusion and little or no memory of
the event that caused the concussion but no
loss of consciousness
loss of consciousness lasting a few minutes to
several hours with brief to extended confusion
upon return of consciousness and no memory
of the event that caused the concussion
Treatment Options and Outlook
Treatment is generally watchful waiting. The doctor
may choose to hospitalize the person for close
medical observation or may recommend regularly
arousing the person for 24 to 48 hours to monitor
the person’s ability to exhibit full consciousness.
Most concussions are mild and recovery is complete.
However, severe or repeated concussions
can lead to permanent brain damage or even
death. It is important to monitor a person who has
had a concussion for changes in alertness, behavior,
and symptoms such as headache and to seek
medical reevaluation if they occur.
Risk Factors and Preventive Measures
The most common causes of concussion are MOTOR
VEHICLE ACCIDENTS, team sports (especially contact
sports such as football and boxing), bicycle accidents,
and shaking an infant or young child.
Never shake an infant or young child,
even in play. Infants and young children
are particularly vulnerable to
BRAIN injury that can occurs with forceful
shaking (shaken baby syndrome).
The damage can cause concussion or,
when severe, be permanent or fatal.
Collisions and crashes when downhill skiing,
snowboarding, roller skating, inline skating, and
skateboarding are also common causes of concussion.
Measures to reduce the risk for concussion
and other injuries include using appropriate personal
protective equipment and devices, such as
safety belts and helmets; following safety procedures
and regulations; and proper training and
technique when participating in sporting activities.
See also TRAUMA PREVENTION; TRAUMATIC BRAIN
INJURY (TBI).
consciousness A state of awareness of one’s
external environment, typically when a person is
awake and the cerebrum (the largest part of the
BRAIN responsible for sensory, voluntary, and cognitive
functions) is fully functional. Most
researchers believe consciousness results from the
interactions of physiology, chemistry, cognition,
and memory. However, scientists do not fully
understand how consciousness occurs. A clinical
assessment of consciousness typically incorporates
measures of how well a person is oriented to current
events and surroundings. Altered states of
consciousness range from sleep, from which a person
is easily aroused, to COMA, from which a person
cannot be aroused. A network of nerves in the
brainstem, midbrain, and cerebral cortex, the
reticular-activating system (RAS), is primarily
responsible for regulating the level of consciousness.
See also COGNITIVE FUNCTION AND DYSFUNCTION;
DELIRIUM; HALLUCINATION; MEMORY AND MEMORY
IMPAIRMENT; PERSISTENT VEGETATIVE STATE; UNCON-
SCIOUSNESS.