Editing Head injury (section)

==Classification==
Head injuries include both injuries to the brain and those to other parts of the head, such as the [[scalp]] and [[human skull|skull]]. Head injuries can be closed or open. A closed (non-missile) head injury is where the [[dura mater]] remains intact. The skull can be fractured, but not necessarily. A [[penetrating head injury]] occurs when an object pierces the skull and breaches the dura mater. Brain injuries may be [[Focal and diffuse brain injury|diffuse]], occurring over a wide area, or focal, located in a small, specific area. A head injury may cause [[skull fracture]], which may or may not be associated with injury to the brain. Some patients may have linear or depressed skull fractures. If [[intracranial hemorrhage]] occurs, a [[hematoma]] within the skull can put pressure on the brain. Types of intracranial hemorrhage include [[subdural hemorrhage|subdural]], [[subarachnoid hemorrhage|subarachnoid]], [[extradural hematoma|extradural]], and [[intraparenchymal hematoma]]. [[Craniotomy]] surgeries are used in these cases to lessen the pressure by draining off the blood.

[[Brain damage|Brain injury]] can occur at the site of impact, but can also be at the opposite side of the skull due to a ''[[Coup contrecoup injury|contrecoup]]'' effect (the impact to the head can cause the brain to move within the skull, causing the brain to impact the interior of the skull opposite the head-impact). While impact on the brain at the same site of injury to the skull is the coup effect. If the impact causes the head to move, the injury may be worsened, because the brain may ricochet inside the skull causing additional impacts, or the brain may stay relatively still (due to inertia) but be hit by the moving skull (both are contrecoup injuries).

Specific problems after head injury can include<ref name=":0">{{cite book | last1 = Daisley | first1 = Audrey | last2 = Kischka | first2 = Udo | last3 = Tams | first3 = Rachel | name-list-style = vanc | title = Head Injury | date = 2008 | publisher = OUP Oxford | location = Oxford |url=https://books.google.com/books?id=PnzkLAlQ0LgC| isbn = 9780191578717 }}</ref><ref name=":1">{{cite book | last1 = Macfarlane | first1 = Robert | last2 = Hardy | first2 = David G. | name-list-style = vanc | title = Outcome after Head, Neck and Spinal Trauma: a medicolegal guide|date=1997|publisher=Reed Educational and Professional Publishing Ltd.|location=Oxford|isbn=978-0-7506-2178-6}}</ref><ref name=":2">{{cite book|last1=Powell|first1=Trevor| name-list-style = vanc |title=Head Injury: A Practical Guide|date=2004|publisher=Speech mark publishing Ltd.|location=United Kingdom|isbn=978-0-86388-451-1|edition= 2nd}}</ref>
{{columns-list|colwidth=30em|
* Skull fracture
* [[Laceration]]s to the scalp and resulting [[hemorrhage]] of the skin
* Traumatic [[subdural hematoma]], a bleeding below the [[dura mater]] which may develop slowly
* Traumatic extradural, or [[epidural hematoma]], bleeding between the dura mater and the skull
* Traumatic subarachnoid hemorrhage
* [[Cerebral contusion]], a bruise of the brain
* [[Concussion]], a loss of function due to trauma
* [[Dementia pugilistica]], or "punch-drunk syndrome", caused by repetitive head injuries, for example in boxing or other contact sports
* A severe injury may lead to a [[coma]] or [[death]]
* [[Shaken baby syndrome]] – a form of child abuse
}}

===Concussion===

{{main|Concussion|Pediatric concussion}}
[[File:Coup injury.jpg|thumb|[[Coup injury]]]]

A concussion is a form of a mild traumatic brain injury (TBI). This injury is a result due to a blow to the head that could make the person's physical, cognitive, and emotional behaviors irregular. Symptoms may include clumsiness, [[Fatigue (medical)|fatigue]], [[confusion]], [[nausea]], [[Blurred vision|blurry vision]], [[headache]]s, and others.<ref>{{cite web|title=Concussion - Symptoms and causes|url=https://www.mayoclinic.org/diseases-conditions/concussion/symptoms-causes/syc-20355594|access-date=2020-10-16|website=Mayo Clinic|language=en}}</ref> Mild concussions are associated with [[sequela]]e.<ref>{{cite journal | vauthors = Rao V, Syeda A, Roy D, Peters ME, Vaishnavi S | title = Neuropsychiatric aspects of concussion: acute and chronic sequelae | journal = Concussion | volume = 2 | issue = 1 | pages = CNC29 | date = March 2017 | pmid = 30202570 | pmc = 6094361 | doi = 10.2217/cnc-2016-0018 }}</ref> Severity is measured using various [[concussion grading systems]].

A slightly greater injury is associated with both anterograde and retrograde [[amnesia]] (inability to remember events before or after the injury). The amount of time that the amnesia is present correlates with the severity of the injury. In all cases, the patients develop [[post concussion syndrome]], which includes memory problems, dizziness, tiredness, sickness and [[Major depressive disorder|depression]]. Cerebral [[concussion]] is the most common head injury seen in children.<ref name=":3">{{cite journal | vauthors = Arciniegas DB, Anderson CA, Topkoff J, McAllister TW | title = Mild traumatic brain injury: a neuropsychiatric approach to diagnosis, evaluation, and treatment | journal = Neuropsychiatric Disease and Treatment | volume = 1 | issue = 4 | pages = 311–27 | date = December 2005 | pmid = 18568112 | pmc = 2424119 }}</ref>

===Intracranial bleeding===
{{Main|Intracranial hemorrhage}}
Types of intracranial hemorrhage are roughly grouped into intra-axial and extra-axial.  The hemorrhage is considered a [[focal and diffuse brain injury|focal brain injury]]; that is, it occurs in a localized spot rather than causing diffuse damage over a wider area.

====Intra-axial bleeding====
{{Main|cerebral hemorrhage}}
Intra-axial hemorrhage is bleeding within the brain itself, or [[cerebral hemorrhage]]. This category includes [[intraparenchymal hemorrhage]], or bleeding within the brain tissue, and [[intraventricular hemorrhage]], bleeding within the brain's [[ventricular system|ventricle]]s (particularly of [[Premature birth|premature infants]]). Intra-axial hemorrhages are more dangerous and harder to treat than extra-axial bleeds.<ref name="Brant07">{{cite book |author=Seidenwurm DI |veditors=Brant WE, Helms CA |chapter=Introduction to brain imaging |title=Fundamentals of Diagnostic Radiology |publisher=Lippincott, Williams & Wilkins |location=Philadelphia |year=2007 |page=53 |isbn=978-0-7817-6135-2 |access-date=2008-11-17 |chapter-url=https://books.google.com/books?id=Sossht2t5XwC&q=extra-axial+intra-axial&pg=PA53 |url-status=live |archive-url=https://web.archive.org/web/20171106031550/https://books.google.com/books?id=Sossht2t5XwC&pg=PA53&lpg=PA53&dq=extra-axial+intra-axial |archive-date=2017-11-06 }}</ref>

====Extra-axial bleeding====
{{Epidural vs. subdural hematoma}}

Extra-axial hemorrhage, bleeding that occurs within the skull but outside of the brain tissue, falls into three subtypes:
* [[Epidural hemorrhage]] (extradural hemorrhage)  which occur between the [[dura mater]] (the outermost [[meninx]]) and the skull, is caused by trauma.  It may result from laceration of an artery, most commonly the [[middle meningeal artery]]. This is a very dangerous type of injury because the bleed is from a high-pressure system and deadly increases in [[intracranial pressure]] can result rapidly. However, it is the least common type of meningeal bleeding and is seen in 1% to 3% cases of head injury.
** Patients have a loss of consciousness (LOC), then a [[lucid interval]], then sudden deterioration (vomiting, restlessness, LOC)
** Head CT shows lenticular (convex) deformity.
* [[Subdural hemorrhage]] results from tearing of the bridging veins in the [[subdural space]] between the [[dura mater|dura]] and [[arachnoid mater]].
** Head CT shows crescent-shaped deformity
* [[Subarachnoid hemorrhage]], which occur between the arachnoid and [[pia mater|pia]] meningeal layers, like intraparenchymal hemorrhage, can result either from trauma or from ruptures of [[aneurysm]]s or [[arteriovenous malformation]]s.  Blood is seen layering into the brain along [[sulcus (neuroanatomy)|sulci]] and [[fissure (anatomy)|fissure]]s, or filling [[Cistern (neuroanatomy)|cistern]]s (most often the [[suprasellar cistern]] because of the presence of the [[blood vessel|vessel]]s of the [[circle of Willis]] and their branch points within that space). The classic presentation of subarachnoid hemorrhage is the sudden onset of a severe headache (a [[thunderclap headache]]). This can be a very dangerous entity and requires emergent neurosurgical evaluation and sometimes urgent intervention.

==== Cerebral contusion ====
{{main|Cerebral contusion}}
Cerebral contusion is bruising of the brain tissue. The piamater is not breached in contusion in contrary to lacerations. The majority of contusions occur in the [[frontal lobe|frontal]] and [[temporal lobe]]s. Complications may include cerebral [[edema]] and transtentorial herniation. The goal of treatment should be to treat the increased [[intracranial pressure]]. The prognosis is guarded.

==== Diffuse axonal injury ====
{{main|Diffuse axonal injury}}
[[Diffuse axonal injury]], or DAI, usually occurs as the result of an [[acceleration]] or deceleration motion, not necessarily an impact. [[Axon]]s are stretched and damaged when parts of the brain of differing density slide over one another. Prognoses vary widely depending on the extent of the damage.

==== Compound head injury ====
Overlying scalp laceration and soft tissue disruption in continuity with a skull fracture constitutes "compound head injury", and has higher rates of infection, unfavorable neurologic outcome, delayed seizures, mortality, and duration of hospital stay.<ref>{{cite journal |last1=Dhandapani |first1=S |last2=et |first2=al. |title=Validation of a New Clinico-Radiological Grading for Compound Head Injury: Implications on the Prognosis and the Need for Surgical Intervention. |journal=World Neurosurg |date=Nov 2015 |volume=84 |issue=5 |pages=1244–50 |doi=10.1016/j.wneu.2015.05.058 |pmid=26054870 |url=https://doi.org/10.1016/j.wneu.2015.05.058}}</ref>