Brain anatomyBrain anatomy

Mechanism of injury in head Mechanism of injury in head traumatrauma

►Direct trauma by compression or Direct trauma by compression or crushing.crushing.

►Acceleration-Deceleration InjuriesAcceleration-Deceleration Injuries Brain has inertia. For example, when a person falls backwards onto a Brain has inertia. For example, when a person falls backwards onto a

hard floor, the back of the personhard floor, the back of the person’’s head hits the floor and stops. The s head hits the floor and stops. The brain, however, is still moving until it strikes the inside of the skull. If brain, however, is still moving until it strikes the inside of the skull. If the brain gets bruised, there is bleeding, also called a hemorrhage. the brain gets bruised, there is bleeding, also called a hemorrhage.

This bleeding causes further damage to the brain.This bleeding causes further damage to the brain. The skull does not need to strike an object in order for the brain to get The skull does not need to strike an object in order for the brain to get

injured. There are many situations in motor vehicle crashes where the injured. There are many situations in motor vehicle crashes where the forces are transmitted through the brain without the skull hitting the forces are transmitted through the brain without the skull hitting the dashboard, windshield, steering wheel or window.dashboard, windshield, steering wheel or window.

Coup/Contrer-CoupCoup/Contrer-Coup Injuries:Injuries: Related to acceleration-deceleration injuriesRelated to acceleration-deceleration injuries (e.g injury to temporal lobe in contralateral temporal trauma) (e.g injury to temporal lobe in contralateral temporal trauma)

Head TraumaHead Trauma

11--Skull fracturesSkull fractures..

22--Extradural ,subdural & subarachinoidExtradural ,subdural & subarachinoid..

33--Cerebral contusion& intraventricular Cerebral contusion& intraventricular HgeHge..

44--Diffuse Axonal Injury (DAI)Diffuse Axonal Injury (DAI)..

55--Related Brain edema & herniationRelated Brain edema & herniation..

Skull FractureSkull Fracture

►A skull fracture is a break in the skull A skull fracture is a break in the skull bone and generally occurs as a result bone and generally occurs as a result of direct impact .of direct impact .

►Uncomplicated skull fractures Uncomplicated skull fractures themselves rarely produce neurologic themselves rarely produce neurologic deficit, but the associated intracranial deficit, but the associated intracranial injury may have serious neurologic injury may have serious neurologic sequelae. sequelae.

►Four major types of skull fractures may Four major types of skull fractures may occur:occur:

► (1) linear,(1) linear,► (2) depressed,(2) depressed,► (3) diastatic, (3) diastatic, ►(4) basilar. (4) basilar.

Linear skull fracturesLinear skull fractures

Depressed skull fracturesDepressed skull fractures

Cech Petr

Basilar skull fracturesBasilar skull fractures

► Most basilar fractures Most basilar fractures occur at 2 specific occur at 2 specific anatomic locations anatomic locations —— namely, the temporal namely, the temporal region and the occipital region and the occipital condylar region. condylar region.

Other TypesOther Types► Ping-pong skull Ping-pong skull

fracturesfractures . .

► Birth fracturesBirth fractures (Caput (Caput succedaneum or succedaneum or cephalohematoma ).cephalohematoma ).

► Growing skull Growing skull fracturesfractures (leptomeningeal cyst, (leptomeningeal cyst, traumatic meningocele, traumatic meningocele, cerebrocranial erosion, cerebrocranial erosion, cephalhydrocele, cephalhydrocele, meningocele, and meningocele, and spuria. spuria.

Epidural HematomaEpidural Hematoma►An epidural hematoma is usually An epidural hematoma is usually

associated with a skull fracture. It often associated with a skull fracture. It often occurs when occurs when adirect impact adirect impact fractures the fractures the calvarium .calvarium .

►The fractured bone lacerates a dural The fractured bone lacerates a dural artery (middle meningeal artery) or a artery (middle meningeal artery) or a venous sinus. venous sinus.

►On CT, the hematoma forms a On CT, the hematoma forms a hyperdense biconvex mass. It is usually hyperdense biconvex mass. It is usually uniformly high density but may contain uniformly high density but may contain hypodense foci due to active bleeding. hypodense foci due to active bleeding.

►Comment on Comment on midline shift .midline shift .

Natasha RichardsonNatasha Richardson

March 2009March 2009

Subdural HematomaSubdural Hematoma ►Deceleration and acceleration or rotationalDeceleration and acceleration or rotational

forces that tear bridging veins can cause an acute forces that tear bridging veins can cause an acute subdural hematoma so it occurs in cases of wide subdural hematoma so it occurs in cases of wide subdural space(old age & children)subdural space(old age & children)

Causes of subdural are:in minimal trauma in old age, Causes of subdural are:in minimal trauma in old age, child abuse and ventricular decompression, may child abuse and ventricular decompression, may occur in patients receiving anticoagulants or occur in patients receiving anticoagulants or patients with a coagulopathy condition.patients with a coagulopathy condition.

► The blood collects in the space between the The blood collects in the space between the arachnoid matter and the dura matter, Because arachnoid matter and the dura matter, Because the subdural space is not limited by the cranial the subdural space is not limited by the cranial sutures, blood can spread along the entire sutures, blood can spread along the entire hemisphere and into the hemispheric fissure, hemisphere and into the hemispheric fissure, limited only by the dural reflections .limited only by the dural reflections .

► We have 3 major types :We have 3 major types :

Acute, subacute & chronicAcute, subacute & chronic

Acute Subdural Acute Subdural HematomaHematoma

Crescent shaped;Crescent shaped; Hyperdense, may contain hypodense Hyperdense, may contain hypodense foci due to serum, CSF or active foci due to serum, CSF or active bleeding bleeding

► In children, subdural hematomas In children, subdural hematomas occurring along the posterior occurring along the posterior interhemispheric fissure and the interhemispheric fissure and the tentorium have been described tentorium have been described as common findings following as common findings following violent nonaccidental shaking violent nonaccidental shaking (ie, shaken baby syndrome) .(ie, shaken baby syndrome) .

Subacute Subdural Subacute Subdural HematomaHematoma

► Subacute SDH may be difficult to visualize by Subacute SDH may be difficult to visualize by CT because as the hemorrhage is reabsorbed CT because as the hemorrhage is reabsorbed it becomes it becomes isodense to normal gray matterisodense to normal gray matter. A . A subacute SDH should be suspected when you subacute SDH should be suspected when you identify shift of midline structures without an identify shift of midline structures without an obvious mass. Giving contrast may help in obvious mass. Giving contrast may help in difficult cases because the interface between difficult cases because the interface between the hematoma and the adjacent brain usually the hematoma and the adjacent brain usually becomes more obvious due to enhancement becomes more obvious due to enhancement of the dura and adjacent vascular structures. of the dura and adjacent vascular structures. Some of the notable characteristics of Some of the notable characteristics of subacute SDH are:subacute SDH are:- Compressed lateral ventricle- Compressed lateral ventricle& or midline shift& or midline shift

- Effaced sulci .- Effaced sulci .

Chronic Subdural HematomaChronic Subdural Hematoma

► Chronic SDH becomes Chronic SDH becomes low density as the low density as the hemorrhage is further hemorrhage is further reabsorbed. It is reabsorbed. It is usually uniformly low usually uniformly low density but may be density but may be loculated. Rebleeding loculated. Rebleeding often occurs and often occurs and causes mixed density causes mixed density and fluid levels.and fluid levels.

Subarachnoid HemorrhageSubarachnoid Hemorrhage ►A subarachnoid hemorrhage occurs A subarachnoid hemorrhage occurs

with injury of small arteries or veins on with injury of small arteries or veins on the surface of the brain. The ruptured the surface of the brain. The ruptured vessel bleeds into the space between vessel bleeds into the space between the pia and arachnoid matter. The most the pia and arachnoid matter. The most common cause of subarachnoid common cause of subarachnoid hemorrhage is trauma .hemorrhage is trauma .

► In the absence of significant trauma, In the absence of significant trauma, the most common cause of the most common cause of subarachnoid hemorrhage is the subarachnoid hemorrhage is the rupture of a cerebral aneurysm.rupture of a cerebral aneurysm.

► When When traumatictraumatic, , subarachnoid hemorrhage subarachnoid hemorrhage occurs most commonly over occurs most commonly over the cerebral convexities or the cerebral convexities or adjacent to otherwise injured adjacent to otherwise injured brain (i.e. adjacent to a brain (i.e. adjacent to a cerebral contusion) cerebral contusion)

► If there is a large amount of If there is a large amount of SAH particularly in the SAH particularly in the basilarcisterns,sulci&fissures basilarcisterns,sulci&fissures the physician should the physician should consider whether a consider whether a ruptured ruptured aneurysmaneurysm led to the led to the subsequent trauma. subsequent trauma.

Cerebral ContusionCerebral Contusion ► Brain contusions commonly are identified in patients with Brain contusions commonly are identified in patients with

traumatic brain injury (traumatic brain injury (TBITBI) .) .► The second mechanism is related to The second mechanism is related to countercoupcountercoup

acceleration or deceleration ,which causes the brain to acceleration or deceleration ,which causes the brain to strike the skull. In an event in which the head is in motion, strike the skull. In an event in which the head is in motion, cortical injury occurs adjacent to the floor of the anterior or cortical injury occurs adjacent to the floor of the anterior or posterior cranial fossa, the sphenoid wing, the petrous posterior cranial fossa, the sphenoid wing, the petrous ridge, the convexity of the skull, and the falx or tentorium. ridge, the convexity of the skull, and the falx or tentorium. The inferior The inferior frontal and temporalfrontal and temporal lobes are particularly lobes are particularly vulnerable vulnerable

► Cerebral contusions are the most common primary intra-Cerebral contusions are the most common primary intra-axial injury. They often occur when the brain impacts an axial injury. They often occur when the brain impacts an osseous ridge or a dural fold. The foci of punctate osseous ridge or a dural fold. The foci of punctate hemorrhage or edema are located along gyral crests. The hemorrhage or edema are located along gyral crests. The following are common locations:following are common locations:- Temporal lobe - anterior tip, inferior surface, sylvian - Temporal lobe - anterior tip, inferior surface, sylvian regionregion- Frontal lobe - anterior pole, inferior surface- Frontal lobe - anterior pole, inferior surface- Dorsolateral midbrain- Dorsolateral midbrain- Inferior cerebellum- Inferior cerebellum

► On CT, cerebral contusion appears as an ill-On CT, cerebral contusion appears as an ill-defined hypodense area mixed with foci of defined hypodense area mixed with foci of hemorrhage. Adjacent subarachnoid hemorrhage. Adjacent subarachnoid hemorrhage is common. hemorrhage is common. After 24-48 hoursAfter 24-48 hours, , hemorrhagic transformation or coalescence of hemorrhagic transformation or coalescence of petechial hemorrhages into a rounded petechial hemorrhages into a rounded hematoma is commonhematoma is common

► CT scans often demonstrate progression over CT scans often demonstrate progression over time in the size and number of contusions and time in the size and number of contusions and the amount of hemorrhage within the contusionsthe amount of hemorrhage within the contusions

► MRIMRI findings typically demonstrate the lesions findings typically demonstrate the lesions from the onset of injury, but many facilities from the onset of injury, but many facilities cannot perform MRI on an emergent basis cannot perform MRI on an emergent basis

► On MRI, contusions are isointense to On MRI, contusions are isointense to hyperintense on T1-weighted and hyperintense hyperintense on T1-weighted and hyperintense on T2-weighted image& The signal intensity is on T2-weighted image& The signal intensity is increased in the affected region on DWIs .increased in the affected region on DWIs .

Diffuse Axonal InjuryDiffuse Axonal Injury ► Diffuse axonal injury is often referred to as "shear Diffuse axonal injury is often referred to as "shear

injury". It is the most common cause of significant injury". It is the most common cause of significant morbidity in CNS trauma. Fifty percent of all morbidity in CNS trauma. Fifty percent of all primary intra-axial injuries are diffuse axonal primary intra-axial injuries are diffuse axonal injuries .injuries .

► When shearing forces occurWhen shearing forces occur  in areas of greater in areas of greater density differential,density differential,  the axons suffer trauma; the axons suffer trauma; thisthis  results inresults in  edema and in axoplasmic leakage edema and in axoplasmic leakage (which is(which is  most severe during the first 2 most severe during the first 2 weeksweeks  following injury). The exact location of the following injury). The exact location of the shear-strain injury depends on the plane of rotation shear-strain injury depends on the plane of rotation

► Immediate loss of consciousness is typical of these Immediate loss of consciousness is typical of these injuries .injuries .

The true extent of axonal injury typically is worse The true extent of axonal injury typically is worse than that visualized using current imaging than that visualized using current imaging techniques The CT of a patient with diffuse techniques The CT of a patient with diffuse axonal injury may be normal despite the axonal injury may be normal despite the patient's presentation with a profound patient's presentation with a profound neurological deficit .neurological deficit .

► With CT, diffuse axonal injury may appear With CT, diffuse axonal injury may appear as ill-defined areas of high density or as ill-defined areas of high density or hemorrhage in characteristic locations. hemorrhage in characteristic locations.

► One or more small intraparenchymal One or more small intraparenchymal (petechial) hemorrhages (petechial) hemorrhages less than 2 cm in less than 2 cm in diameter, locateddiameter, located  in the cerebral in the cerebral hemispheres at the grey white interfacehemispheres at the grey white interface as as well as corpus callosum &brainstem.well as corpus callosum &brainstem.

► One may also observe small One may also observe small focal areas of focal areas of low density low density on CT scans; these correspond on CT scans; these correspond to areas of edema to areas of edema

► Stage I -Stage I -  This involves the parasagittal regions of This involves the parasagittal regions of the frontal lobes, the periventricular temporal the frontal lobes, the periventricular temporal lobes, and, less likely, the parietal and occipital lobes, and, less likely, the parietal and occipital lobes, internal and external capsules, and lobes, internal and external capsules, and cerebellum.cerebellum.

► Stage II - ThisStage II - This  involves the corpus callosum in involves the corpus callosum in addition to the white-matter areasaddition to the white-matter areas  of stage I.of stage I.  Most Most commonly, the posterior body and splenium are commonly, the posterior body and splenium are involved; however, the process is believed to involved; however, the process is believed to advance anteriorly with increasing severity of advance anteriorly with increasing severity of disease. Both sides of the corpus callosum may disease. Both sides of the corpus callosum may be involved; however, involvement more be involved; however, involvement more frequently is unilateral and may be hemorrhagic. frequently is unilateral and may be hemorrhagic. The involvement of the corpus callosum carries a The involvement of the corpus callosum carries a poorer prognosis.poorer prognosis.

► Stage III - This involves the areas associated with Stage III - This involves the areas associated with stage II, with the addition of brainstem stage II, with the addition of brainstem involvement. A predilection exists for the superior involvement. A predilection exists for the superior cerebellar peduncles, medial lemnisci, and cerebellar peduncles, medial lemnisci, and corticospinal tracts .corticospinal tracts .

Intraventricular HemorrhageIntraventricular Hemorrhage

► Traumatic Traumatic intraventricular intraventricular hemorrhage is hemorrhage is associated with diffuse associated with diffuse axonal injury, deep axonal injury, deep gray matter injury, and gray matter injury, and brainstem contusion. brainstem contusion. An isolated An isolated intraventricular intraventricular hemorrhage may be hemorrhage may be due to rupture of due to rupture of subependymal veins .subependymal veins .

Cerebral EdemaCerebral Edema► Severe brain edema Severe brain edema

or a large or a large intracranial intracranial hemorrhage may hemorrhage may cause downward cause downward brain displacement brain displacement and coning, which is and coning, which is usually fatal usually fatal

StrokeStrokeStroke is a clinical term for sudden, focal Stroke is a clinical term for sudden, focal

neurological deficitneurological deficit Hemorrhagic Hemorrhagic

strokesstrokes ► due to rupture of due to rupture of

a cerebral blood a cerebral blood vessel that causes vessel that causes bleeding into or bleeding into or around the brain .around the brain .

► account for 16% of account for 16% of all strokes .all strokes .

ischemic strokeischemic stroke ► caused by blockage caused by blockage

of blood flow in a of blood flow in a major cerebral major cerebral blood vessel, blood vessel, usually due to a usually due to a blood clot .blood clot .

► account for about account for about 84% of all strokes. 84% of all strokes.

Hemorrhagic StrokeHemorrhagic StrokeHemorrhagic strokes account for 16% of all Hemorrhagic strokes account for 16% of all

strokesstrokes► Intracerebral hge is Intracerebral hge is

the most common, the most common, accounting for 10% accounting for 10% of all strokes .of all strokes .

► Subarachnoid hge, Subarachnoid hge, due to rupture of a due to rupture of a cerebral aneurysm, cerebral aneurysm, accounts for 6% of accounts for 6% of strokes overall. strokes overall.

Now Dudes tell me what are the reasons of Now Dudes tell me what are the reasons of cerebral hemorrhage!???cerebral hemorrhage!???

1.1. Hypertensive hemorrhageHypertensive hemorrhage . .2.2. Amyloid angiopathy.Amyloid angiopathy.3.3. Ruptured vascular malformation.Ruptured vascular malformation.4.4. Coagulopathy(A fluid level within the Coagulopathy(A fluid level within the

hematoma) .hematoma) .5.5. Hemorrhage into a tumor .Hemorrhage into a tumor .6.6. Venous infarction.Venous infarction.7.7. Drug abuse. Drug abuse.

Subarachnoid Subarachnoid HemorrhageHemorrhage

► Common aneurysm locations include the Common aneurysm locations include the anterior and posterior communicating anterior and posterior communicating arteries, the middle cerebral artery arteries, the middle cerebral artery bifurcation and the tip of the basilar bifurcation and the tip of the basilar artery. artery.

► Subarachnoid hemorrhage typically Subarachnoid hemorrhage typically presents as the presents as the "worst headache of life" "worst headache of life" for the patient .for the patient .

Ischemic strokeIschemic stroke Ischemic strokes are caused by thrombosis, embolism Ischemic strokes are caused by thrombosis, embolism

of thrombosis, hypoperfusion and lacunar of thrombosis, hypoperfusion and lacunar infarctions(1%)infarctions(1%)

► A thrombotic strokeA thrombotic stroke (53%)occurs when a (53%)occurs when a blood clot forms in blood clot forms in situ within a situ within a cerebral artery and cerebral artery and blocks or reduces blocks or reduces the flow of blood the flow of blood through the artery through the artery

► An embolic strokeAn embolic stroke

(30%) occurs when a (30%) occurs when a detached clot flows detached clot flows into and blocks a into and blocks a cerebral artery cerebral artery

► A CT is 58% sensitive A CT is 58% sensitive for infarction within for infarction within the first 24 hours the first 24 hours (Bryan et al, 1991). (Bryan et al, 1991). MRI is 82% sensitive. MRI is 82% sensitive. If the patient is If the patient is imaged greater than imaged greater than 24 hours after the 24 hours after the event, both CT and event, both CT and MR are greater than MR are greater than 90% sensitive. 90% sensitive.

► After a stroke, edema After a stroke, edema progresses, and brain progresses, and brain density decreases density decreases proportionately. proportionately.

Diffuse Hypodensity and Diffuse Hypodensity and Sulcal EffacementSulcal Effacement

► Hypodensity in Hypodensity in greater than one-greater than one-third of the middle third of the middle cerebral artery cerebral artery territory is generally territory is generally considered to be a considered to be a contra-indication to contra-indication to thrombolytic thrombolytic therapy. therapy.

Hyperdense Vessel SignHyperdense Vessel Sign

► A hyperdense vessel A hyperdense vessel is defined as a is defined as a vessel denser than vessel denser than its counterpart and its counterpart and denser than any denser than any non-calcified vessel non-calcified vessel of similar size. of similar size.

► This sign indicates This sign indicates poor outcome and poor outcome and poor response to IV-poor response to IV-TPA therapy. TPA therapy.

Basilar ThrombosisBasilar Thrombosis

► Thrombosis of the Thrombosis of the basilar artery is a basilar artery is a common finding in common finding in stroke patients. CT stroke patients. CT findings include a findings include a dense basilar artery dense basilar artery without contrast without contrast injection.injection.

Lentiform Nucleus Lentiform Nucleus ObscurationObscuration

Subacute InfarctionSubacute Infarction -Increasing mass effect-Increasing mass effect

- Wedge shaped low - Wedge shaped low densitydensity- Hgic transformation- Hgic transformationAfter 4 - 7 days the CTAfter 4 - 7 days the CT - Gyral enhancement- Gyral enhancement- Persistent mass effect- Persistent mass effectIn 1-8 weeks:In 1-8 weeks:- Mass effect resolves- Mass effect resolves- Enhancement may - Enhancement may persist persist

Chronic InfarctionChronic Infarction

Case 1Case 1

Gunshot injury leading to Gunshot injury leading to brain contusion,localized brain contusion,localized

subarachnoid hemorrhage & subarachnoid hemorrhage & skull fracture at the site of skull fracture at the site of

the bullet entrythe bullet entry

Case 2Case 2

Depressed skull Depressed skull fracture,pneumocephalyfracture,pneumocephaly

Case 3Case 3

Subacute subdural Subacute subdural hematomahematoma

Case 4Case 4

Chronic subdural hematoma Chronic subdural hematoma with fluid fluid level with fluid fluid level

secondary to new bleeding secondary to new bleeding &mix of recent and old blood&mix of recent and old blood

Case 5Case 5

Intraventricular Intraventricular hemorrhage,extending from hemorrhage,extending from

intracerebral hgeintracerebral hge

Case 6Case 6

Ischemic cerebral strokeIschemic cerebral strokeHyperdense vessel sign of Hyperdense vessel sign of

MCAMCA

Case 8Case 8

Chronic cerebral infarctionChronic cerebral infarction

Case 9Case 9

Brain contusion(TBI)Brain contusion(TBI)