A penetrating head injury, or open head injury, is a
head injury
A head injury is any injury that results in trauma to the skull or brain. The terms ''traumatic brain injury'' and ''head injury'' are often used interchangeably in the medical literature. Because head injuries cover such a broad scope of inju ...
in which the
dura mater
In neuroanatomy, dura mater is a thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord. It is the outermost of the three layers of membrane called the meninges that protect the central nervous system. ...
, the outer layer of the
meninges
In anatomy, the meninges (, ''singular:'' meninx ( or ), ) are the three membranes that envelop the brain and spinal cord. In mammals, the meninges are the dura mater, the arachnoid mater, and the pia mater. Cerebrospinal fluid is located in th ...
, is breached.
[University of Vermont College of Medicine]
"Neuropathology: Trauma to the CNS."
Accessed through web archive on August 8, 2007. Penetrating injury can be caused by high-
velocity
Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity is a ...
projectiles
A projectile is an object that is propelled by the application of an external force and then moves freely under the influence of gravity and air resistance. Although any objects in motion through space are projectiles, they are commonly found in ...
or objects of lower velocity such as knives, or bone fragments from a
skull fracture
A skull fracture is a break in one or more of the eight bones that form the cranial portion of the human skull, skull, usually occurring as a result of blunt force trauma. If the force of the impact is excessive, the bone may fracture at or near ...
that are driven into the brain. Head injuries caused by
penetrating trauma
Penetrating trauma is an open wound injury that occurs when an object pierces the skin and enters a tissue of the body, creating a deep but relatively narrow entry wound. In contrast, a blunt or ''non-penetrating'' trauma may have some deep dama ...
are serious
medical emergencies
A medical emergency is an acute injury or illness that poses an immediate risk to a person's life or long-term health, sometimes referred to as a situation risking "life or limb". These emergencies may require assistance from another, qualified p ...
and may cause permanent
disability
Disability is the experience of any condition that makes it more difficult for a person to do certain activities or have equitable access within a given society. Disabilities may be Cognitive disability, cognitive, Developmental disability, dev ...
or
death
Death is the irreversible cessation of all biological functions that sustain an organism. For organisms with a brain, death can also be defined as the irreversible cessation of functioning of the whole brain, including brainstem, and brain ...
.
A penetrating head injury involves "a wound in which an object breaches the cranium but does not exit it." In contrast, a perforating head injury is a wound in which the object passes through the head and leaves an
exit wound.
[Vinas FC and Pilitsis J. 2006]
"Penetrating Head Trauma."
Emedicine.com. Retrieved on February 6, 2007.
Cause
![Phineas gage - 1868 skull diagram](https://upload.wikimedia.org/wikipedia/commons/2/28/Phineas_gage_-_1868_skull_diagram.jpg)
In penetrating injury from high-velocity missiles, injuries may occur not only from initial
laceration
A wound is a rapid onset of injury that involves lacerated or punctured skin (an ''open'' wound), or a contusion (a ''closed'' wound) from blunt force trauma or compression. In pathology, a ''wound'' is an acute injury that damages the epiderm ...
and crushing of brain tissue by the
projectile
A projectile is an object that is propelled by the application of an external force and then moves freely under the influence of gravity and air resistance. Although any objects in motion through space are projectiles, they are commonly found in ...
, but also from the subsequent
cavitation
Cavitation is a phenomenon in which the static pressure of a liquid reduces to below the liquid's vapour pressure, leading to the formation of small vapor-filled cavities in the liquid. When subjected to higher pressure, these cavities, cal ...
. High-velocity objects create rotations and can create a
shock wave
In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a med ...
that cause stretch injuries, forming a cavity that is three to four times greater in
diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for ...
than the missile itself.
A pulsating temporary cavity is also formed by a high-speed missile and can have a diameter 30 times greater than that of the missile.
Though this cavity is reduced in size once the force ends, the tissue that was compressed during cavitation remains injured. Destroyed brain tissue may either be ejected from
entrance or
exit wounds, or packed up against the sides of the cavity formed by the missile.
Low-velocity objects usually cause penetrating injuries in the regions of the
skull
The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...
's
temporal bone
The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebral cortex.
The temporal bones are overlaid by the sides of the head known as the temples, and house the structures of the ears. Th ...
s or
orbital surfaces, where the bones are thinner and thus more likely to break.
Damage from lower-velocity penetrating injuries is restricted to the tract of the stab wound, because the lower-velocity object does not create as much cavitation.
However, low-velocity penetrating objects may ricochet inside the skull, continuing to cause damage until they stop moving.
[Brain Injury Association of America (BIAUSA)]
"Types of Brain Injury."
Retrieved on February 6, 2007.
Pathophysiology
Though it is more likely to cause
infection
An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...
, penetrating trauma is similar to
closed head injury Closed-head injury is a type of traumatic brain injury in which the skull and dura mater remain intact. Closed-head injuries are the leading cause of death in children under 4 years old and the most common cause of physical disability and cognitive ...
such as
cerebral contusion
Cerebral contusion, Latin ''contusio cerebri'', a form of traumatic brain injury, is a bruise of the brain tissue.
Like bruises in other tissues, cerebral contusion can be associated with multiple microhemorrhages, small blood vessel leaks into ...
or
intracranial hemorrhage
Intracranial hemorrhage (ICH), also known as intracranial bleed, is bleeding within the skull. Subtypes are intracerebral bleeds ( intraventricular bleeds and intraparenchymal bleeds), subarachnoid bleeds, epidural bleeds, and subdural bleeds. ...
. As in closed head injury,
intracranial pressure
Intracranial pressure (ICP) is the pressure exerted by fluids such as cerebrospinal fluid (CSF) inside the skull and on the brain tissue. ICP is measured in millimeters of mercury (mmHg) and at rest, is normally 7–15 Millimeter of mercury, mmHg ...
is likely to increase due to
swelling or bleeding, potentially crushing delicate brain tissue. Most deaths from penetrating trauma are caused by damage to
blood vessel
The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away ...
s, which can lead to
intracranial hematoma
Intracranial hemorrhage (ICH), also known as intracranial bleed, is bleeding within the skull. Subtypes are intracerebral bleeds ( intraventricular bleeds and intraparenchymal bleeds), subarachnoid bleeds, epidural bleeds, and subdural bleeds. ...
s and
ischemia
Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems wi ...
, which can in turn lead to a
biochemical cascade
A biochemical cascade, also known as a signaling cascade or signaling pathway, is a series of chemical reactions that occur within a biological cell when initiated by a stimulus. This stimulus, known as a first messenger, acts on a receptor that ...
called the
ischemic cascade
The ischemic (ischaemic) cascade is a series of biochemical reactions that are initiated in the brain and other aerobic tissues after seconds to minutes of ischemia (inadequate blood supply). This is typically secondary to stroke, injury, or card ...
. The injury in penetrating brain trauma is mostly
focal (that is, it affects a specific area of tissue).
Studies with
PET scan
Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, r ...
ning and
transcranial Doppler
Transcranial Doppler (TCD) and transcranial color Doppler (TCCD) are types of Doppler ultrasonography that measure the velocity of blood flow through the brain's blood vessels by measuring the echoes of ultrasound waves moving transcranially (thr ...
imaging
Imaging is the representation or reproduction of an object's form; especially a visual representation (i.e., the formation of an image).
Imaging technology is the application of materials and methods to create, preserve, or duplicate images.
...
have shown that changes in
cerebral blood flow
Cerebral circulation is the movement of blood through a network of cerebral arteries and veins supplying the brain. The rate of cerebral blood flow in an adult human is typically 750 milliliters per minute, or about 15% of cardiac output. Arterie ...
, such as
hypoperfusion
Perfusion is the passage of fluid through the circulatory system or lymphatic system to an organ or a tissue, usually referring to the delivery of blood to a capillary bed in tissue. Perfusion is measured as the rate at which blood is deliver ...
and
vasospasm
Vasospasm refers to a condition in which an arterial spasm leads to vasoconstriction. This can lead to tissue ischemia and tissue death (necrosis). Cerebral vasospasm may arise in the context of subarachnoid hemorrhage. Symptomatic vasospasm or de ...
, can follow penetrating head injury.
These changes can last for two weeks.
An
ischemic cascade
The ischemic (ischaemic) cascade is a series of biochemical reactions that are initiated in the brain and other aerobic tissues after seconds to minutes of ischemia (inadequate blood supply). This is typically secondary to stroke, injury, or card ...
similar to the course of cellular and metabolic events that follow other head injuries may follow penetrating head injuries.
Sometimes in penetrating injuries, the brain releases
thromboplastin
Thromboplastin (TPL) is derived from cell membranes and is a mixture of both phospholipids and tissue factor, neither of which are enzymes. Thromboplastin acts on and accelerates the activity of Factor Xa, also known as thrombokinase, aiding blood ...
, which can lead to problems with
blood clot
A thrombus (plural thrombi), colloquially called a blood clot, is the final product of the blood coagulation step in hemostasis. There are two components to a thrombus: aggregated platelets and red blood cells that form a plug, and a mesh of c ...
ting.
[Orlando Regional Healthcare, Education and Development. 2004]
"Overview of Adult Traumatic Brain Injuries."
Retrieved on January 16, 2008.
While
blunt trauma to the head does not present a risk of
shock
Shock may refer to:
Common uses Collective noun
*Shock, a historic commercial term for a group of 60, see English numerals#Special names
* Stook, or shock of grain, stacked sheaves
Healthcare
* Shock (circulatory), circulatory medical emergen ...
due to hemorrhage, penetrating head trauma does.
Diagnosis and treatment
A person with a penetrating head injury may be evaluated using
X-ray
An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...
,
CT scan, or
MRI
Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves ...
(MRI can only be used when the penetrating object would not be magnetic, because MRI uses magnetism and could move the object, causing further injury).
Surgery
Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pat ...
may be required to
debride
Debridement is the medical removal of dead, damaged, or infected tissue to improve the healing potential of the remaining healthy tissue. Removal may be surgical, mechanical, chemical, autolytic (self-digestion), and by maggot therapy.
In po ...
or repair the injury or to relieve excessive
intracranial pressure
Intracranial pressure (ICP) is the pressure exerted by fluids such as cerebrospinal fluid (CSF) inside the skull and on the brain tissue. ICP is measured in millimeters of mercury (mmHg) and at rest, is normally 7–15 Millimeter of mercury, mmHg ...
.
Intracranial pressure is monitored and attempts are made to maintain it within normal ranges.
Intravenous fluids are given and efforts are taken to maintain high
blood oxygen levels.
Prognosis
The highest-velocity injuries tend to have the worst associated damage.
[Dawodu S. 2007]
"Traumatic Brain Injury: Definition, Epidemiology, Pathophysiology"
Emedicine.com. Retrieved on February 6, 2007. A study published in 1991, which documented 314 individuals who had had penetrating cranial injuries caused by gunshot wounds, found that 73% died from their injuries at the scene of the incident, and a further 19% ultimately died later, thus indicating a total mortality rate of 92%.
Perforating injuries have an even worse prognosis.
Penetrating head trauma can cause impairment or loss of abilities controlled by parts of the brain that are
damaged. A famous example is
Phineas Gage
Phineas P. Gage (18231860) was an American railroad construction foreman known for his improbable survival of an accident in which a large iron rod was driven completely through his head, destroying much of his brain's left frontal lobe, and ...
, whose personality appears to have changed (though not as dramatically as usually described) after a perforating injury to his
frontal lobe
The frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere (in front of the parietal lobe and the temporal lobe). It is parted from the parietal lobe by a groove betwe ...
(s).
People with
subarachnoid hemorrhage
Subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space—the area between the arachnoid membrane and the pia mater surrounding the brain. Symptoms may include a severe headache of rapid onset, vomiting, decreased level of consci ...
, a
blown pupil
Mydriasis is the dilation of the pupil, usually having a non-physiological cause, or sometimes a physiological pupillary response. Non-physiological causes of mydriasis include disease, trauma, or the use of certain types of drugs.
Normally, as ...
,
respiratory distress
Shortness of breath (SOB), also medically known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing disc ...
,
hypotension
Hypotension is low blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. Blood pressure is indicated by two numbers, the systolic blood pressure (the top number) and the dias ...
, or
cerebral vasospasm Cerebral vasospasm is the prolonged, intense vasoconstriction of the larger conducting arteries in the subarachnoid space which is initially surrounded by a clot.
Significant narrowing of the blood vessels in the brain develops gradually over the ...
are more likely to have worse outcomes.
People with penetrating head trauma may have complications such as
acute respiratory distress syndrome
Acute respiratory distress syndrome (ARDS) is a type of respiratory failure characterized by rapid onset of widespread inflammation in the lungs. Symptoms include shortness of breath (dyspnea), rapid breathing (tachypnea), and bluish skin colo ...
,
disseminated intravascular coagulation
Disseminated intravascular coagulation (DIC) is a condition in which blood clots form throughout the body, blocking small blood vessels. Symptoms may include chest pain, shortness of breath, leg pain, problems speaking, or problems moving parts o ...
, and
neurogenic
In Biology, biology, the nervous system is the Complex system, highly complex part of an animal that coordinates its Behavior, actions and Sense, sensory information by transmitting action potential, signals to and from different parts of its ...
pulmonary edema
Pulmonary edema, also known as pulmonary congestion, is excessive edema, liquid accumulation in the parenchyma, tissue and pulmonary alveolus, air spaces (usually alveoli) of the lungs. It leads to impaired gas exchange and may cause hypoxemia an ...
.
Up to 50% of patients with penetrating brain injuries get late-onset
post-traumatic epilepsy
Post-traumatic epilepsy (PTE) is a form of acquired epilepsy that results from brain damage caused by physical trauma to the brain (traumatic brain injury, abbreviated TBI). A person with PTE experiences repeated post-traumatic seizures (PTS, s ...
.
[Shepherd S. 2004]
"Head Trauma."
Emedicine.com. Retrieved on February 6, 2007.
See also
*
Brain herniation
Brain herniation is a potentially deadly side effect of very high pressure within the skull that occurs when a part of the brain is squeezed across structures within the skull. The brain can shift across such structures as the falx cerebri, the te ...
*
Traumatic brain injury
A traumatic brain injury (TBI), also known as an intracranial injury, is an injury to the brain caused by an external force. TBI can be classified based on severity (ranging from mild traumatic brain injury TBI/concussionto severe traumatic b ...
References
External links
{{Trauma , state=autocollapse
Neurotrauma
Injuries of head