Slide Chapt 2-Basic Pathology and Anatomy

7/25/2019 Slide Chapt 2-Basic Pathology and Anatomy

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Basic Pathology, Anatomy, and

Pathophysiology of Stroke

Caplans Stroke A Clinical Approach 4th Edition

Chapter 2


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PAT!"!#$%

&ECA'(S&S !) CE*EB*!+ASC"A* -A&A#E T!

B*A(' T(SSE

There are two major categories of brain damage in stroke patients:

(1) ischemia

(2) hemorrhage

Ischemia can be further subdivided into 3 mechanisms:

Thrombosis,

mbo!ism,"ecreased #$stemic %erfusion&


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Throm.osis

Thrombosis refers to an

obstruction of b!ood 'ow due to

a !oca!ied occ!usive process

within one or more b!ood

vesse!s&

-ecreased Systemic

Perf/sion

In decreased s$stemicperfusion, diminished

f!ow to brain tissue is caused b$

!ow s$stemic

perfusion pressure&

Em.olism

ateria! formed e!sewhere

within the vascu!ar s$stem

!odges in an arter$ and b!ocksb!ood 'ow&

*!ockage can be transient or

ma$ persist for hours or da$s

before moving dista!!$&


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#+*,-,./01I"I0T-.-*-

%I"+-#+*"+-,2

different causes, posedifferent c!inica!

prob!ems, and havedifferent management&

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/--/


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#ubarachnoid /emorrhage

rteriovenous ma!formations that cause

the s$ndrome of subarachnoid

hemorrhage are either !ocated in the

brain, abutting on pia! or ventricu!ar

surfaces, or situated within the ventricu!ar

s$stem or the subarachnoid space&

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Intracerebra! and parench$ma!

hemorrhage describe b!eeding direct!$ into

the brain substance& The cause is most often h$pertension,

with !eakage of b!ood from sma!!

intracerebra! arterio!es damaged b$ thee!evated b!ood pressure

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Intracerebra! hemorrhage


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The most common brain !ocations for

h$pertensive intracerebra! hemorrhages

are as fo!!ows: !atera! gang!ionic andcapsu!ar (456), tha!amus (126), !obar

white matter (176 to 256), caudate

nuc!eus (86), pons (86), and cerebe!!um(86)29,1&

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These hemorrhages are a!most a!wa$s

caused b$ head trauma& #ubdura! hemorrhages arise from injured

veins that are !ocated between the dura

mater and the arachnoid membranes&

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#ubdura! < epidura!

hemorrhage


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pidura! hemorrhages are caused b$

tearing of meningea! arteries, most often

the midd!e meningea! arter$&

*!ood accumu!ates rapid!$ over minutes to

hours between the sku!! and the dura

mater

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The prob!ems in these =ve major subt$pes

of stroke are >uite distinct and re>uire

different treatment strategies&

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#T-? ./0I# +I"

T-T0T

#ome therapies suitab!e for ischemia wou!d be

disastrous if the prob!em were hemorrhage


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major important >uestion in ever$ stroke

patient is@where is the brain and vascu!ar

prob!em !ocatedA

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0TB: .0 0TI. #IT#

C D#.+- 0" *-I0 #I0#


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%/B#IB 0" %T/%/B#IB

C *-I0 I#./I

(schemia0orma! etabo!ism and *!ood C!ow

.erebra! b!ood 'ow (.*C) is norma!!$ approEimate!$ 75m for each 155 g of brain tissue per minute, and

cerebra! oE$gen consumption, usua!!$ measured as the

cerebra! metabo!ic rate for oE$gen (.-2), is norma!!$

approEimate!$ 3&7 mF155 g per minute

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oca! brain effects of ischemia t b!ood 'ow !eve!s of approEimate!$ 25

mF155 g per minute,

e!ectroencepha!ographic () activit$ is

affected&

.-2 a!so begins to fa!! when .*C is

diminished be!ow 25 mF155 g per minute&

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rteria! occ!usion and reaction

Dascu!ar occ!usion most often begins with

formation of atherosc!erotic p!a>ues within

eEtracrania! and !arge intracrania! arteries& These p!a>ues contain a miEture of !ipid,

smooth musc!e, =brous and co!!agen

tissues, macrophages, and in'ammator$ce!!s

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therosc!erotic p!a>ues and vascu!ar

stenosis cause brain ischemia in a variet$of wa$s&

%rogressive intima! thickening !eads to

stenosis or occ!usion of the arter$,

resu!ting in reduced dista! b!ood 'ow&

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Trombus formation

Thrombi form in situ when the bod$Gs

coagu!ation s$stem has been activated

and the b!ood is h$percoagu!ab!e /$percoagu!abi!it$ can be a !ife!ong

hereditar$ prob!em& #$stemic diseases,

such as cancer, regiona! enteritis, andthromboc$tosis, can cause increased

c!otting&

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The surviva! of the brain regions at risk

depends on a number of factors

(1) the ade>uac$ of co!!atera! circu!ation

(2) the state of the s$stemic circu!ation

(3) sero!ogic factors

(4) changes within the obstructing

vascu!ar !esion

(7) resistance within the microcircu!ator$

bed&

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*rain edema and increased

intracrania! pressure There are two t$pes of brain edema:

(1) water accumu!ation inside ce!!s,

termed c$totoEic edema (2) 'uid within the eEtrace!!u!ar space,

often termed vasogenic edema

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Intracrania! pressure ma$ a!so be increased,

!eading to increased morbidit$ and decreased

.*C&

Hhen intracrania! pressure is increased, the

pressure in the venous sinuses and draining

veins must a!so increase if b!ood is to be drained

norma!!$ from the cranium& *rain edema and increased intracrania! pressure

a!so cause headache, decreased

consciousness, and vomiting&71


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Slide Chapt 2-Basic Pathology and Anatomy