Facts on File Encyclopedia of Health and Medicine

there are no outward indications that a concus-
sion has occurred.

Because the potential for serious BRAIN

damage exists even with an apparently

minor concussion, a person who experi-

ences a blow to the head that results in

loss of CONSCIOUSNESS or symptoms of

concussion that last longer than 15 min-

utes should undergo examination by a

physician.

The diagnostic path includes a basic NEUROLOGIC
EXAMINATIONto assess the person’s level of CON-
SCIOUSNESSand REFLEXresponses. The doctor may
conduct diagnostic imaging procedures such as
COMPUTED TOMOGRAPHY(CT) SCANorMAGNETIC 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.

GRADING OF CONCUSSION
grade 1 brief confusion but no loss of CONSCIOUSNESS

grade 2 extended confusion and little or no memory of
the event that caused the concussion but no
loss of consciousness

grade 3 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 doc-
tor 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 com-
plete. 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, behav-
ior, 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 acci-

dents, and shaking an infant or young child.

Never shake an infant or young child,

even in play. Infants and young chil-

dren are particularly vulnerable to

BRAINinjury that can occurs with force-

ful 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 concus-

sion. Measures to reduce the risk for concussion

and other injuries include using appropriate per-

sonal protective equipment and devices, such as

safety belts and helmets; following safety proce-

dures 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

BRAINresponsible for sensory, voluntary, and cog-

nitive 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 cur-

rent events and surroundings. Altered states of

consciousness range from sleep, from which a per-

son is easily aroused, to COMA, from which a per-

son 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 conscious-

ness.

See also COGNITIVE FUNCTION AND DYSFUNCTION;

DELIRIUM; HALLUCINATION; MEMORY AND MEMORY

IMPAIRMENT; PERSISTENT VEGETATIVE STATE; UNCON-

SCIOUSNESS.

consciousness 245