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CT SCANS AND CEREBRAL/BRAIN

HAEMORRHAGES:

A RADIOGRAPHERS PERSPECTIVE.


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The humannervoussystem

Central nervoussystem(CNS)

BrainSpinal

cord

Peripheral nervous system(PNS) . (Thenerves extending to and from the brain

and spinal cord)

Motor (efferent)neurons

Autonomicnervous system

Somatic nervoussystem

Sensory(afferent)neurons

BASIC ANATOMY AND PHYSIOLOGY OF THE BRAIN AND

THE NERVOUS SYSTEM


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The anterior and posterior

cerebral arteries and theposterior

and single anterior communicating

arteries form the circle of Willis,

The major arteries are :

ANTERIOR CEREBRAL ARTERIES

ANTERIOR COMMUNICATING ARTERY

INTERNAL CAROTID ARTERIES

MIDDLE CEREBRAL ARTERIES

ANTERIOR CHOROIDAL ARTERIES

POSTERIOR COMMUNICATING

ARTERIES

POSTERIOR CEREBRAL ARTERIES

SUPERIOR CEREBELLAR ARTERIESBASILAR ARTERY

VERTEBRAL ARTERIES

THE BLOOD SUPPLY TO THE BRAIN


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THE MENINGESThe brain is wrapped in three connective tissue membranes.

The innermost pia matermembrane contains the blood vessels.

The brain is nourished and cushioned by cerebrospinal fluid, which is contained between

the pia materand the arachnoid mater.The outermost dura mater membrane lines the inside of the skull and is comparatively

thick and tough. , it encloses the arachnoid materand the pia mater-

Reproduced from [Marieb 1991])


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SPIRAL CT SCANS AND BLEEDS

CT is a vital tool in the assessment of patients with serious head injury. It

revolutionized management when it was introduced and remains the investigation ofchoice even following the advent of MRI, due both to the ease of monitoring of injured

patients and the better demonstration of fresh bleeding and bony injury.

([email protected]). With multi-slice spiral CT scanners short scan times are

possible,e.g. the scan time for a complete unconstrasted brain CT is about 9-10

seconds.

The spiral CT scanner has the ability to produce multiplanar and 3 and/or 4 D images

during post processing, with actual scanning taking place in one plane only.

Only one dose of radiation is necessary and specialized software packages are used

to manipulate the acquired information as desired to best demonstrate the

patho/physiology.

Spiral CT can also be used to demonstrate spontaneous bleeds and also allows for CT

angiography to demonstrate abnormalities of the blood vessels , for example

aneurysms and arteriovenous malformations.

If a CT is indicated, skull x-rays are not necessary and may only cause delay.


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BRAIN HAEMORRHAGES

A brain haemorrhage - is bleeding in and/or around the brain that can be caused bytrauma(Traumatic brain injury-TBI) or can occur spontaneously.

TBI can result in compression injury to the adjacent brain (coup) and stretching on theopposite side (contrecoup). This may result in contusion,shearing injuries and rupture of

the intra-axial or extra-axial vessels, leading to haemorrhage.There are four main types ofhaemorrhages:

Epidural/extradural haemorrhage(EDA),Subdural haemorrhage (SDH),

Subarachnoid haemorrhage(SAH)Intracerebral haemorrhage(ICH). These include HAEMORRHAGIC CONTUSIONS.

SDH,EDH and SAH, are extra-axial bleeds, occurring outside of the brain tissue, whileintra-axial bleeds ,including intraparenchymal and intraventricular haemorrhages occur

within it.SDH and EDHmost commonly arise after trauma to the brain.

SAH and ICH are more likely to occur spontaneously, but there is a likelihood of a SAHoccurring simultaneously with SDH ,EDH or ICH.

Urgent investigation and treatment is needed, as depending on the severity, brainhaemorrhages can result in permanent brain damage or death.

The long-term effects of a haemorrhage depends on the type and location, but as with allbrain injuries, every person's recovery is individual.


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Epidural/ Extradural Haemorrhages (Haematoma)

Epidural orExtradural Haemorrhage is caused by TBI, in which a buildup of blood occurs

between the dura materand the skull. The dura mater also covers the spine, so epidural

bleeds may also occur in the spinal column. EDH commonly results from acceleration-deceleration trauma and transverse forces. EDHs are extra-axial bleeds.

An EDH occurs when there is a rupture of a blood vessel, usually an artery, but can be a vein.

The affected vessels are often torn by skull fractures. Venous epidural bleeds are usually due

to shearing injury from rotational or linear forces, caused when tissues of different densities

slide over one another.

EDH is potentially deadly because the buildup of blood may increase pressure in the

intracranial space (raised intracranial pressure), and compress delicate brain tissue. If the

patient is not treated with prompt surgical intervention, death is likely to follow.

The bleeding is usually acute and of high attenuation and there is often significant mass effect

with compression of the ipsilateral lateral ventricle and dilatation of the opposite lateral

ventricle due to obstruction of the foramen of Munro (interventricular foramen). The basalcisterns may be effaced.

Epidural haematoma is usually found on the same side of the brain that was impacted by the

blow, but on very rare occasions it can be due to a contrecoup injury.


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On CT scans, epidural haemorrhages usually appear biconvex in shape, with a

well defined margin, because their expansion stops at skull's sutures where the

dura mater is tightly attached to the skull. Thus they expand inward toward the

brain rather than along the inside of the skull. The lens like shape of the

haematoma leads the appearance of these bleeds to be called "lentiform".

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Examples

Fig 1.This is the typical appearance and location of an acute

extradural haematoma.

Note the high density of the haematoma. Slight midline shift is

present

Fig 2. This example shows a more unusual, lower location. Note also

the gas within the haematoma - this indicates a basal skull fracture or,

as in this case, it is post surgical. Note also the dilated lateral ventricleon the opposite side.

Fig 1 Fig 2

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fig 3fig 4

Fig. 3 Right frontal acute EDH with an air bubble, and midline shift.

Fig. 4 shows a 3 D CT image demonstrating skull fractures.

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On March 18, 2009, actress Natasha Richardson died as a result of anepidural hematoma sustained two days earlier while skiing in Mont-

Tremblant, Qubec, Canada.Like many patients, she had a lucid

interval where she did not exhibit any symptoms until approximately

an hour after her fall when she complained of a headache. By the

time she reached medical care, the hematoma had already causedsignificant damage.

Extracts taken from: ^Autopsy: Natasha Richardson died from hitting head,Associated Press, March 19,

2009


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As with an EDH an acute SDH is associated with high mortality and morbidity

rates and is therefore treated as an emergency. Differentiating the two is

therefore not so important in the acute situation. SDH presents in a similar

fashion to the EDH, and can have equally severe consequences due to mass

effect, requiring urgent surgery.

An acute SDH is a rapidly clotting blood collection below the inner layer of thedura but external to the brain and arachnoid membrane,(extra-axial) often

from ruptured veins crossing this potential space.

Two further stages, subacute and chronic SDH, may develop with untreated

acute SDH. Each type has distinctly different clinical, pathological, and

imaging characteristics.

SUBDURAL HAEMORRHAGE (SDH)


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The blood is again of high attenuation, but may spread more widely in the

subdural space, with a crescentic appearance and a more irregular inner

margin on CT.

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EXAMPLES OF SUBDURAL HAEMATOMAS

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Chronic SDHS are probably due to trauma. Symptoms arevague and often develop slowly with a gradual depression or

fluctuation of consciousness.

While acute SDH have increased attenuation, this

decreases with time, becoming isodense after a week or so,

and hypodense thereafter, therefore chronic subdurals are

often hypodense crescentic collections, often with masseffect.

Expansion due to osmosis may tear veins further leading to

recurrent bleeds; hyperdense red blood cells from fresh

bleeding may layer posteriorly, and complex septated

collections may develop.

Isodense collections may be better demonstrated after

intravenous contrast as the density will then be less than that

of the brain. However this is rarely a problem since the

introduction of Multi-slice CT scanners

CHRONIC SUBDURALS

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Note the crescentic low densitycollection typical of a chronicsubdural haematoma, with

associated midline shift.

This is the same case, higher up.

Note the dilated opposite lateral

ventricle.

Midline shift often distorts the Foramen

of Munro of the opposite side causing

obstruction.

Chronic(hypodense)subdural

This haematoma is not so old and is

almost isodense. It is probably about

one to two weeks old. This could be

missed on older scanners with poorer

quality images, but this is rarely aproblem now.


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SUBARACHNOID HAEMORRHAGE (SAH)-

extracts from Julia Barrett.

A potentially life-threatening condition where blood leaks out of blood vessels over

the surface of the brain. The classic symptom of subarachnoid hemorrhage is a

thunderclap headache.

The bleeding occurs in the arteries that run underneath the arachnoid membrane,

thereby damaging the brain tissue. The reduction of blood supply can also cause

further brain damage, leading to disruption or loss of brain function and possibly

death.

SAH,S are classified into two general categories:

TraumaticSAH - brain injury that might be sustained in an accident or a fall.

Spontaneous SAH -occur with little or no warning and frequently arise

because of ruptured aneurysms or blood vessel abnormalities.

Spontaneous SAH are often due to an aneurysm which bursts. Arteriovenous

malformation (AVMs), which are abnormal interfaces between arteries and veins,

may also rupture and release blood into the subarachnoid space. Both conditions are

associated with weak spots in the walls of blood vesselsaccounts for 60% of all

spontaneous SAH.


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The immediate danger due to SAH, is ischemia. Ischemia refers to tissue damage

caused by restricted or blocked blood flow. The areas of the brain that do not

receive adequate blood and oxygen can suffer irreparable injury, leading to

permanent brain damage orDEATH. Anyone surviving the initial hemorrhage issusceptible to a number of complications in the following hours, days, and weeks.

The most common complications are raised intracranial pressure, vasospasm

(blood vessel constriction), and hydrocephalus.

A raised intracranial pressure , can lead to further bleeding from damaged bloodvessels; a complication associated with a 70% fatality rate.

Vasospasm,, is a principal cause of secondary ischemia. As the blood vessels

become narrower, blood flow in the brain becomes increasingly restricted.

Approximately one third of spontaneous subarachnoid hemorrhages and 30-60% of

traumatic bleeds are followed by vasospasm.

Hydrocephalus due to restricted circulation of cerebrospinal fluid, follows

approximately 15% of subarachnoid hemorrhages. Because cerebrospinal fluid

cannot drain properly, pressure accumulates on the brain, possibly prompting furtherischemic complications.


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Examples of SAH


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Intracerebral hemorrhage, (ICH) occurs within the brain tissue itself, i.e. it is

intraparenchymal.

ICH can be caused by brain trauma, or it can occur spontaneously.

A ICH is an intra-axial hemorrhage; that is, it occurs within the brain tissue rather than

outside of it.

Intracerebral bleeds are the second most common cause of stroke. High blood pressure

raises the risk of spontaneous intracerebral hemorrhage.

Intraparenchymal bleeds due to trauma are usually due to penetrating head trauma, but

can also be due to depressed skull fractures, acceleration-deceleration trauma, rupture

of an aneurysm or arteriovenous malformation (AVM), and bleeding within a tumor.A

very small proportion is due to cerebral venous sinus thrombosis.

The risk of death from an intraparenchymal bleed in traumatic brain injury is especially highwhen the injury occurs in the brain stem. Intraparenchymal bleeds within the medulla are

almost always fatal, because they cause damage to the vagus nerve, which plays an

important role in blood circulation and breathing.This kind of haemorrhage can also occur

in the cortex orsub cortical areas, usually in the frontal or temporal lobes when due to

head injury, and sometimes in the cerebellum.

INTRACEREBRAL HAEMORRHAGE


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These occur due to stretching and shearing injuries, often

due to impaction of the brain against the skull on the sideopposite to the injury.

Thus they may be seen directly opposite the impact

site, subcutaneous haematoma, fracture, or

extradural haematoma (contre coup injury).

. HAEMORRHAGIC CONTUSIONS

There is a focal area of haemorrhagic contusion in the right

frontal lobe, with surrounding low density due to infarction

or oedema. This is a frequent location for a contre-coup

injury following a blow to the back of the head.


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INTRACEREBRALBLEEDS, CONTUSIONSAND

INTRAVENTRICULARBLEEDS

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MULTIPLE PETECHIALHAEMORRHAGES( multifocal haemorrhagic contusion)

Multiple contusions may be present throughout the cerebral

hemispheres.They are often very small and visible at the grey/white matter

interface.

They are due to a shearing injury with rupture of small

intracerebral vessels, and in a comatose patient with no other

obvious cause they imply a severe diffuse brain injury with a poor

prognosis.

Larger haemorrhages may occur in severe trauma, and they maynot be apparent on a scan performed immediately after the injury,

only becoming prominent after a day or two. MRI is more sensitive

to diffuse brain injury, particularly in the absence of haemorrhage.

This image demonstrates a small petechial

haemorrhage in a typical location at the grey-whitematter interface (arrow).

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FRACTURES


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BONE SETTINGS-MULTIPLANARAND 3-D

RECONSTRUCTION SHOWINGFRACTURES OF

THE SKULL

SAGITAL

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CORONALAXIAL


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CORONALAXIAL

SAGITAL


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PARASAGITAL

AXIAL


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CT ANGIOGRAPHY OF THE VESSELS OF THE BRAIN

SHOWING ANEURYSMS


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RECONSTRUCTED BY RADIOLOGIST DR S MURPHY


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SOME ACTIVITIES TO STAY AWAY FROM


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REFERENCES1. Ben Pansky,Ph.D.,M.D.1975. Review of gross Anatomy.

2. Retrieved from "http://en.wikipedia.org/wiki/Cerebral_hemorrhage"

3. University of Vermont College of Medicine. "Neuropathology: Trauma to

the CNS."Accessed through web archive. Retrieved on February 6, 2007.4. Brain injury victims can seem OK, symptoms delayed, Associated Press, March

19, 2009 http://www.biomedcentral.com/1471-2377/7/1.

5. ^ MedlinePlus - Intracerebral hemorrhage Update Date: 7/14/2006. Updated by:

J.A. Lee, M.D.

6. ^ Downie A. 2001. "Tutorial: CT in Head Trauma". Retrieved on February 6, 2007.

7. Wagner AL. 2006. "Subdural Hematoma." Emedicine.com. Retrieved on

February 6, 2007.

8. Shepherd S. 2004. "Head Trauma." Emedicine.com. Retrieved on February 6,

2007

9. http://www.neurologyindia.com/article.asp?issn=0028.http://en.wikipedia.org/wiki/Epidural_hematoma, Categories: Neurotrauma | Neurology.


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We've made great medical progress in the last

generation. What used to be merely an itch is

now an allergy.

Anonymous

THANK YOU

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