Focal and diffuse brain injury are ways to classify

brain injury An injury is any physiological damage to living tissue caused by immediate physical stress. An injury can occur intentionally or unintentionally and may be caused by blunt trauma, penetrating trauma, burning, toxic exposure, asphyxiation, or ...

: focal injury occurs in a specific location, while diffuse injury occurs over a more widespread area. It is common for both focal and diffuse damage to occur as a result of the same event; many traumatic brain injuries have aspects of both focal and diffuse injury. Focal injuries are commonly associated with an injury in which the head strikes or is struck by an object; diffuse injuries are more often found in

acceleration In mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by ...

/deceleration injuries, in which the head does not necessarily contact anything, but brain tissue is damaged because tissue types with varying densities accelerate at different rates. In addition to physical trauma, other types of

, such as stroke, can also produce focal and diffuse injuries. There may be primary and secondary brain injury processes.

Focal

A focal traumatic injury results from direct mechanical forces (such as occur when the head strikes a windshield in a vehicle accident) and is usually associated with brain tissue damage visible to the naked eye. A common cause of focal injury is penetrating head injury, in which the skull is perforated, as frequently occurs in auto accidents, blows, and

gunshot wound A gunshot wound (GSW) is a penetrating injury caused by a projectile (e.g. a bullet) from a gun (typically firearm or air gun). Damages may include bleeding, bone fractures, organ damage, wound infection, loss of the ability to move pa ...

s. Focal injuries typically have symptoms that are related to the damaged area of the brain. Stroke can produce focal damage that is associated with signs and symptoms that correspond to the part of the brain that was damaged. For example, if a speech center of the brain such as

Broca's area Broca's area, or the Broca area (, also , ), is a region in the frontal lobe of the dominant hemisphere, usually the left, of the brain with functions linked to speech production. Language processing has been linked to Broca's area since Pier ...

is damaged, problems with speech are common. Focal injuries include the following: * Cerebral contusion is a bruise of brain tissue that commonly results from contact of the brain with the inside of the skull. * Cerebral laceration is a brain injury in which the pia-

arachnoid Arachnoid may refer to: * Relating to arachnids * Arachnoid (astrogeology), a geological structure found only on the planet Venus * Arachnoid (botany), referring to organs with a cobwebby exterior appearance * Arachnoid granulation, small protr ...

is torn. *

Epidural hemorrhage Epidural hematoma is when bleeding occurs between the tough outer membrane covering the brain (dura mater) and the skull. Often there is loss of consciousness following a head injury, a brief regaining of consciousness, and then loss of consciou ...

is bleeding between 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 syste ...

and the skull. It is commonly associated with damage to the middle meningeal artery, often resulting from a skull fracture. * Subdural hemorrhage is bleeding between the dura mater and the arachnoid. *

Intracerebral hemorrhage Intracerebral hemorrhage (ICH), also known as cerebral bleed, intraparenchymal bleed, and hemorrhagic stroke, or haemorrhagic stroke, is a sudden bleeding into the tissues of the brain, into its ventricles, or into both. It is one kind of bleed ...

is bleeding within the brain tissue itself. *

Intraventricular hemorrhage Intraventricular hemorrhage (IVH), also known as intraventricular bleeding, is a bleeding into the brain's ventricular system, where the cerebrospinal fluid is produced and circulates through towards the subarachnoid space. It can result from ...

is bleeding within the ventricles of the brain.

Diffuse

Diffuse injuries, also called multifocal injuries, include brain injury due to hypoxia,

meningitis Meningitis is acute or chronic inflammation of the protective membranes covering the brain and spinal cord, collectively called the meninges. The most common symptoms are fever, headache, and neck stiffness. Other symptoms include confusion ...

, and damage to

blood vessel Blood vessels are the structures 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 from ...

s. Unlike focal injuries, which are usually easy to detect using imaging, diffuse injuries may be difficult to detect and define; often, much of the damage is

microscopic The microscopic scale () is the scale of objects and events smaller than those that can easily be seen by the naked eye, requiring a lens or microscope to see them clearly. In physics, the microscopic scale is sometimes regarded as the scale be ...

. Diffuse injuries can result from acceleration/deceleration injuries. Rotational forces are a common cause of diffuse injuries; these forces are common in diffuse injuries such as

concussion A concussion, also known as a mild traumatic brain injury (mTBI), is a head injury that temporarily affects brain functioning. Symptoms may include loss of consciousness (LOC); memory loss; headaches; difficulty with thinking, concentratio ...

and

diffuse axonal injury Diffuse axonal injury (DAI) is a brain injury in which scattered lesions occur over a widespread area in white matter tracts as well as grey matter. DAI is one of the most common and devastating types of traumatic brain injury and is a major cause ...

. The term "diffuse" has been called a misnomer, since injury is often actually multifocal, with multiple locations of injury. Diffuse injuries include the following: *

Diffuse axonal injury Diffuse axonal injury (DAI) is a brain injury in which scattered lesions occur over a widespread area in white matter tracts as well as grey matter. DAI is one of the most common and devastating types of traumatic brain injury and is a major cause ...

is widespread damage to the

white matter White matter refers to areas of the central nervous system (CNS) that are mainly made up of myelinated axons, also called tracts. Long thought to be passive tissue, white matter affects learning and brain functions, modulating the distributi ...

of the brain that usually results from acceleration/deceleration types of injury. *

Ischemic 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 ...

brain injury resulting from an insufficient blood supply to the brain, is one of the leading causes of

secondary brain damage Primary and secondary brain injury are ways to classify the injury processes that occur in brain injury. In traumatic brain injury (TBI), primary brain injury occurs during the initial insult, and results from displacement of the physical struc ...

after head trauma. * Vascular injury usually causes death shortly after an injury. Although it is a diffuse type of brain injury itself, diffuse vascular injury is generally more likely to be caused by focal than diffuse injury. * Swelling, commonly seen after TBI, can lead to dangerous increases in

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 mmHg for a supine adult. ...

. Though swelling itself is a diffuse type of injury, it can ''result'' from either focal or diffuse injury.

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{{Medical resources , DiseasesDB = , ICD10 = {{ICD10, S, 06, 2, s, 00, {{ICD10, S, 06, 3, s, 00 , ICD9 = , ICDO = , OMIM = , MedlinePlus = , eMedicineSubj = , eMedicineTopic = , MeshID = D001930 Neurotrauma

Focal

Diffuse

See also

References

External links