View source for Medicine:Focal and diffuse brain injury

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| caption         = Epidural hematoma, an example of a focal injury
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'''Focal''' and '''diffuse brain injury''' are ways to classify [[Biology:Brain injury|brain injury]]: 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.<ref name="Lovell94">
{{cite book |chapter = Neuropsychological assessment|vauthors=Lovell MK, Franzen MD |veditors=Silver JM, Yudofsky SC, Hales RE |title=Neuropsychiatry of Traumatic Brain Injury |publisher=American Psychiatric Press |location=Washington, DC |year=1994 |pages= 152–3 |isbn=0-88048-538-8 |access-date=2008-06-17 |url=https://books.google.com/books?id=wugk-4Io1XAC&q=Neuropsychiatry+of+Traumatic+Brain+Injury |quote=Although brain injuries are often described as diffuse or focal in nature, in reality many traumatic brain injuries have both focal and diffuse components.}}
</ref> 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 [[Physics:Acceleration|acceleration]]/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.<ref name="Gennarelli04"/>  In addition to physical trauma, other types of brain injury, such as [[Medicine:Stroke|stroke]], can also produce focal and diffuse injuries.<ref name="Lovell94"/> There may be [[Medicine:Primary and secondary brain injury|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.<ref name="LaPlaca07">
{{cite book|vauthors=LaPlaca MC, Simon CM, Prado GR, Cullen DR |chapter = CNS injury biomechanics and experimental models |pages= 16 |chapter-url = https://books.google.com/books?id=FyzEQPKUuPcC&dq=neurotrauma&pg=PP1 |access-date=2008-06-10 |title=Neurotrauma: New Insights Into Pathology and Treatment|date = 27 July 2007 |editor= Weber JT| isbn=978-0-444-53017-2}}
</ref>  A common cause of focal injury is [[Medicine:Penetrating head injury|penetrating head injury]], in which the skull is perforated, as frequently occurs in auto accidents, blows, and [[Physics:Gunshot wound|gunshot wound]]s.<ref name="LaPlaca07"/> Focal injuries typically have symptoms that are related to the damaged area of the brain.<ref name="LaPlaca07"/> Stroke can produce focal damage that is associated with signs and symptoms that correspond to the part of the brain that was damaged.<ref name="Lovell94"/>  For example, if a speech center of the brain such as [[Biology:Broca's area|Broca's area]] is damaged, problems with speech are common.{{cn|date=May 2022}}

Focal injuries include the following:
* [[Medicine:Cerebral contusion|Cerebral contusion]] is a bruise of brain tissue that commonly results from contact of the brain with the inside of the skull.<ref name="Granacher07"/>
* [[Medicine:Cerebral laceration|Cerebral laceration]] is a brain injury in which the pia-arachnoid is torn.<ref name="Granacher07">
{{cite book |author=Granacher RP |title=Traumatic Brain Injury: Methods for Clinical & Forensic Neuropsychiatric Assessment, Second Edition |publisher=CRC |location=Boca Raton |year=2007 |pages= 26–33|isbn=978-0-8493-8138-6 |access-date=2008-07-06 |url= https://books.google.com/books?id=xt1YFydzXKQC&dq=focal+diffuse+brain+injury+&pg=PA32}}
</ref>
* Epidural hemorrhage is bleeding between the [[Medicine:Dura mater|dura mater]] and the skull.<ref name="Granacher07"/>  It is commonly associated with damage to the middle meningeal artery, often resulting from a [[Medicine:Skull fracture|skull fracture]].
* Subdural hemorrhage is bleeding between the dura mater and the arachnoid.<ref name="Granacher07"/>
* [[Medicine:Intracerebral hemorrhage|Intracerebral hemorrhage]] is bleeding within the brain tissue itself.<ref name="Granacher07"/>
* [[Medicine:Intraventricular hemorrhage|Intraventricular hemorrhage]] is bleeding within the [[Biology:Ventricular system|ventricle]]s of the brain.<ref name="Granacher07"/>

==Diffuse==

Diffuse injuries, also called '''multifocal injuries''', include brain injury due to [[Medicine:Hypoxia (medical)|hypoxia]], [[Medicine:Meningitis|meningitis]], and damage to [[Biology:Blood vessel|blood vessel]]s.<ref name="Gennarelli04">
{{cite book |vauthors=Gennarelli GA, Graham DI |chapter=Neuropathology |veditors=Silver JM, McAllister TW, Yudofsky SC |title=Textbook Of Traumatic Brain Injury |publisher=American Psychiatric Association |location=Washington, DC |year=2005 |pages= 27–34| isbn=1-58562-105-6 |access-date=2008-06-10 |chapter-url = https://books.google.com/books?id=3CuM6MviwMAC&dq=neurotrauma&pg=PA47}}
</ref> 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 [[Engineering:Microscope|microscopic]].<ref name="Granacher07"/> Diffuse injuries can result from acceleration/deceleration injuries.<ref name="Gennarelli04"/> Rotational forces are a common cause of diffuse injuries;<ref name="Schiffer03">
{{cite book |vauthors=Hammeke TA, Gennarelli TA |chapter = Traumatic brain injury |veditors=Schiffer RB, Rao SM, Fogel BS |title=Neuropsychiatry |publisher=Lippincott Williams & Wilkins |location=Hagerstown, MD |year=2003 |pages= 1150 |isbn=0-7817-2655-7 |access-date=2008-06-16 |chapter-url = https://books.google.com/books?id=I2N9COt-4C0C&dq=%22focal+brain+injury%22&pg=PA1150}}
</ref> these forces are common in diffuse injuries such as [[Medicine:Concussion|concussion]] and [[Medicine:Diffuse axonal injury|diffuse axonal injury]].  The term "diffuse" has been called a misnomer, since injury is often actually multifocal, with multiple locations of injury.<ref name="Gennarelli04"/>

Diffuse injuries include the following:
* [[Medicine:Diffuse axonal injury|Diffuse axonal injury]] is widespread damage to the [[Biology:White matter|white matter]] of the brain that usually results from acceleration/deceleration types of injury.<ref name="Granacher07"/>
* Ischemic brain injury resulting from an insufficient blood supply to the brain, is one of the leading causes of secondary brain damage after head trauma.<ref name="Granacher07"/>
* Vascular injury usually causes death shortly after an injury.<ref name="Granacher07"/>  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.<ref name="Granacher07"/>
* Swelling, commonly seen after TBI, can lead to dangerous increases in [[Medicine:Intracranial pressure|intracranial pressure]].<ref name="Granacher07"/>  Though swelling itself is a diffuse type of injury, it can ''result'' from either focal or diffuse injury.<ref name="Granacher07"/>

==See also==
* Focal neurologic deficit

==References==
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[[Category:Neurotrauma]]

{{Sourceattribution|Focal and diffuse brain injury}}