Dr. Ben Wedro practices emergency
medicine at Gundersen Clinic, a
regional trauma center in La Crosse,
Wisconsin. His background includes
undergraduate and medical studies at
the University of Alberta, a Family
Practice internship at Queen's
University in Kingston, Ontario and
residency training in Emergency
Medicine at the University of Oklahoma
Health Sciences Center.
Melissa Conrad Stöppler, MD, is a
U.S. board-certified Anatomic
Pathologist with subspecialty training
in the fields of Experimental and
Molecular Pathology. Dr. Stöppler's
educational background includes a BA
with Highest Distinction from the
University of Virginia and an MD from
the University of North Carolina. She
completed residency training in
Anatomic Pathology at Georgetown
University followed by subspecialty
fellowship training in molecular
diagnostics and experimental
pathology.
Medical Author: Benjamin C.
Wedro, MD, FAAEM
Medical Editors: Melissa Conrad Stöppler, MD
Minor head injuries are a routine
occurrence. From toddlers falling against
tables, kids bumping heads playing ball, to an
elderly person falling down; people often lead
with their heads when they move about.
Usually, a few stars are seen, a headache
happens, and all is well. Sometimes it isn't
so clear. The person may be knocked out for a
few seconds, may vomit, and perhaps may have
some loss of memory but by the time the doctor
visits the bedside, everything is back to
normal. The diagnosis of a concussion is made.
But now what? What do you do with somebody
who acts and appears normal, even though there
was a history of a head injury? Who will have
bleeding in their brain and who won't? Who
needs a CT scan and who just needs to go home?
Traumatic head injuries are a major cause of
death, and disability but it might be best to refer
to the damage done as traumatic brain injury.
The purpose of the head, including the skull and
face, is to protect the brain against injury. In
addition to the bony protection, the brain is
covered in tough fibrous layers called meninges and
bathed in fluid that may provide a little shock
absorption.
When an injury occurs, loss of brain function can
occur even without visible damage to the head. Force
applied to the head may cause the brain to be
directly injured or shaken, bouncing against the
inner wall of the skull. The trauma can potentially
cause bleeding in the spaces surrounding the brain,
bruise the brain tissue, or damage the nerve
connections within the brain.
Caring for the victim with a head injury begins
with making certain that the ABCs of resuscitation
are addressed (airway, breathing, circulation). Many
individuals with head injuries are multiple trauma
victims and the care of their brain may take place
at the same time other injuries are stabilized and
treated.
Skull Fracture
The skull is made up of many bones that form a
solid container for the brain. The face is the front
part of the head and also helps protect the brain
from injury. Depending upon the location of the
fracture, there may or may not be a relationship
between a fractured skull and underlying brain
injury. Of note, a fracture, break, and crack all
mean the same thing, that the integrity of the bone
has been compromised. One term does not presume a
more severe injury than the others. Fractures of the
skull are described based on their location, the
appearance of the fracture, and whether the bone has
been pushed in.
Location is important because some skull bones
are thinner and more fragile than others. For
example, the temporal bone above the ear is
relatively thin and can be more easily broken than
the occipital bone at the back of the skull. The
middle meningeal artery is located in a groove
within the temporal bone. It is susceptible to
damage and bleeding if the fracture crosses that
groove.
Basilar skull fractures
occur because
of blunt trauma and describe a break in the bones
at the base of the skull. These are often
associated with bleeding around the eyes (raccoon
eyes) or behind the ears (Battle's sign). The
fracture line may extend into the sinuses of the
face and allow bacteria from the nose and mouth to
come into contact with the brain, causing a
potential infection.
In infants and young children, whose skull
bones have not yet fused together, a skull
fracture may cause a diastasis fracture, in
which the bone junctions (called suture lines)
widen.
Fractures can be linear (literally a
line in the bone) or stellate (a starburst like
pattern) and the pattern of the break is
associated with the type of force applied to the
skull.
Penetrating skull fractures describe
injuries caused by an object entering the brain.
This includes gunshot and stab wounds, and impaled
objects to the head.
A depressed skull fracture occurs when
a piece of skull is pushed toward the inside of
the skull (think of pressing in on a ping pong
ball). Depending upon circumstances, surgery may
be required to elevate the depressed fragment.
It is important to know whether the fracture
is open or closed (this describes the condition of
the skin overlying the broken bone). An open
fracture occurs when the skin is torn or
lacerated over the fracture site. This increases
the risk of infection, especially with a depressed
skull fracture in which brain tissue is exposed.
In a closed fracture, the skin is not
damaged and continues to protect the underlying
fracture from contamination from the outside
world.
Intracranial Bleeding
Intracranial (intra=within + cranium=skull)
describes any bleeding within the skull.
Intracerebral bleeding describes bleeding within
the brain itself. More specific descriptions are
used based upon where the blood is located.
Bleeding in the skull may or may not be
associated with a skull fracture. An intact skull
is no guarantee that there is not underlying
bleeding, or hemorrhage, in the brain or its
surrounding spaces. For that reason, plain
X-rays of the skull are not routinely
performed.
Epidural, subdural, and subarachnoid bleeding
are terms that describe bleeding in the spaces
between the meninges, the fibrous layered
coverings of the brain. Sometimes, the terms
hemorrhage (bleeding) and
hematoma (blood clot) are interchanged.
Because the skull is a solid box, any blood that
accumulates within the skull can increase the
pressure within it and compress the brain.
Moreover, blood is irritating and can cause
edema or swelling as excess fluid leaks from
the surrounding blood vessels. This is no
different than the swelling that can occur
surrounding a
bruise on an arm or leg. The only difference
is that there is no room within the skull to
accommodate that swelling.
Subdural Hematoma
When force is applied to the head, bridging
veins that cross through the subdural space
(sub=beneath +dura= one of the meninges that line
the brain) can tear and bleed. The resultant blood
clot increases pressure on the brain tissue.
Subdural hematomas can occur at the site of
trauma, or may occur on the opposite side of the
injury (contracoup: contra=opposite + coup=hit)
when the brain accelerates toward the opposite
side of the skull and crushes or bounces against
the opposite side.
Chronic subdural hematoma may occur in
patients who have had atrophy (shrinkage) of their
brain tissue. These include the elderly and
chronic alcoholics. The subdural space increases
and the bridging veins get stretched as they cross
a much wider distance. Minor or unnoticed injuries
can lead to some bleeding, but because there is
enough space in the skull to accommodate the
blood, there may be minimal initial symptoms.
Asymptomatic (producing no symptoms) chronic
subdural hematomas may be left to resolve on their
own; however, it may require attention if the
individual's mental status changes or further
bleeding occurs.
Depending upon the neurologic status of the
affected individual, surgery may be required.
Epidural Hematoma
Thee dura is one of the meninges or lining
membranes that covers the brain. It attaches at
the suture lines where the bones come together. If
the head trauma is epidural (epi=outside +dura)
the blood is trapped in a small area and cause a
hematoma or blood clot to form. Pressure can
increase quickly within the epidural space,
pushing the clot up against the brain and causing
significant damage.
While individuals who sustain small epidural
hematomas may be observed, most require surgery.
Patients have improved survival and brain function
recovery if the operation to remove the hematoma
and relieve pressure on the brain occurs before
they have lost consciousness and become comatose.
An epidural hematoma may often occur with
trauma to the temporal bone located on the side of
the head above the ear. Aside from the fact that
the temporal bone is thinner than the other skull
bones (frontal, parietal, occipital), it is also
the location of the middle meningeal artery that
runs just beneath the bone. Fracture of the
temporal bone is associated with tearing of this
artery and may lead to an epidural hematoma.
Subarachnoid Hemorrhage
In a subarachnoid hemorrhage, blood
accumulates in the space beneath the inner
arachnoid layer of the meninges. The injury is
often associated with an intracerebral bleed (see
below). This is also the space where cerebral
spinal fluid (CSF) flows and affected individuals
can develop severe
headache,
nausea,
vomiting, and a stiff neck because the blood
causes significant irritation to this meningeal
layer. It is the same response that can be seen in
patients who have a
leaking cerebral aneurysm or
meningitis. Treatment is often observation and
controlling the symptoms.
These terms describe bleeding within the brain
tissue itself and can be considered a bruise to
the brain tissue.
Aside from the direct damage to the brain
tissue that was injured, swelling or edema is the
major complication of an intracerebral bleed.
Surgery is not often considered except in
situations in which the pressure within the skull
increases to the point at which part of the bone
is temporarily removed to allow the brain to
expand. When and if the brain swelling resolves,
another operation replaces the piece of skull that
was removed.
Diffuse Axonal Injury or Shear Injury
A potentially devastating brain injury occurs
when the brain injury occurs to the axons, the
part of the neurons or brain cell that allows
those cells to send messages to each other.
Because of the damage of electrical flow between
cells, the affected individual often appears
comatose with no evidence of bleeding within the
brain. The mechanism of injury is usually
acceleration-deceleration, and the nerve endings
that connect the brain cells rip apart.
Treatment is supportive, meaning that there is
no surgery or other treatment presently available.
The patient's basic needs are met hoping that the
brain will recover on its own. Most don't.
Concussions may be potentially considered a
milder form of this type of injury.
Picture of the areas of the brain subject to
injury
Picture of an epidural, subdural, and
intracerebral hematomas
Head Injury Causes
Traumatic head injury affects more than
1.7million people in the United States each year
including almost a half million children; 52,000
people die.
Adults suffer head injuries most frequently due
to falls, motor vehicle crashes, colliding or being
struck by an object, and assaults. Falls and being
struck are the most common causes of head injury in
children.
National traumatic brain injury estimates from
the CDC
