L2 Flashcards
There are three main pathogenic mechanisms for Cerebrovascular diseases ?
• Thrombotic occlusion
• Embolic occlusion
• Vascular rupture
brain may be deprived of oxygen by two general mechanisms:
A. Functional hypoxia
B. Ischemia
causes of functional hypoxia are
- Low partial pressure of oxygen at high altitude
- Severe anemia
- Carbon monoxide poisoning
- Cyanide poisoning
Ischemia of brain occur due to:
tissue hypoperfusion, which can be caused by hypotension, vascular obstruction, or both
It’s can be ( transient or permanent)
Global Cerebral Ischemia:
ischemic-hypoxic injury severe systemic hypotension (systolic pressures below 50 mm Hg)
as in cardiac arrest and shock.
most susceptible neurons in global cerebral ischemia are ?
pyramidal cells of the hippocampus
neocortex and Purkinje cells of the cerebellum.
1-swollen with wide gyri and narrowed sulci.
2- The cut surface shows poor demarcation between gray and white matter.
Global Cerebral Ischemia
Microscopic Appearance in global cerebral haemorrhage
• Early changes
(12 to 24 hours after the injury)
acute neuronal cell change (red neurons)
• Subacute changes
(24 hours to 2 weeks)
Necrosis of tissue, Influx of macrophages
Vascular proliferation, Reactive gliosis
• Repair
(after 2 weeks)
Removal of all necrotic tissue.
Gliosis
Morphology in Global Cerebral Ischemia
1-Border zone (“watershed”) infarcts occur in regions of the brain and spinal cord most distal portions of arterial territories
2- seen after hypotensive episodes.
3- In the cerebral hemispheres, the border zone between the anterior and the middle cerebral artery distributions is at greatest risk.
4-Damage produces a wedge-shaped band of necrosis lateral to the interhemispheric fissure.
Focal Cerebral Ischemia
Cerebral arterial occlusion leads first to:
focal ischemia and then to infarction in the distribution of the compromised vessel
Little or no any collateral flow to structures such as :
- thalamus,
- basal ganglia
- deep white matter (which are supplied by deep penetrating vessels)
so they are more susceptible to Focal Cerebral Ischemia
are a frequent source of emboli in brain ?
Cardiac mural thrombi
is most frequently affected by embolic infarction?
In FCI
The territory of the (((middle cerebral artery))))
a direct extension of the internal carotid artery,
• Emboli tend to lodge where vessels (branch )or in areas
of (stenosis) usually caused by :
atherosclerosis.
Emboli of venous origin may cross over to the
arterial circulation through ?
FCI
a patent foramen ovale
and lodge in the brain (paradoxical embolism)
which include thromboemboli from deep leg veins and fat emboli (usually following bone trauma).
Thrombotic occlusions causing cerebral
infarctions usually are superimposed on?
atherosclerotic plaques.
• Common sites of Thrombotic Occlusions are ?
carotid bifurcation
origin of the middle cerebral artery
either end of the basilar artery
1- results from acute vascular occlusions
2- macroscopic appearance of a evolves over time
3-During the first 6 hours, the tissue is unchanged in appearance,
but by 48 hours, the tissue becomes pale, soft, and swollen
4-From days 2 to 10, the injured brain turns gelatinous and friable.
5-From day 10 to week 3, the tissue -liquefies- eventually leaving a fluid-filled cavity.
Non-Hemorrhagic infarct
1-occurs due to reperfusion of ischemic tissue, either through collaterals or after dissolution of emboli.
2- manifest as multiple, sometimes confluent, petechial hemorrhages
Hemorrhagic infarct
Hemorrhages within the brain are caused by?
• Hypertension
• Arteriovenous malformations
• cavernous malformations
• Tumors
Subarachnoid hemorrhages most commonly are
caused by ?
ruptured aneurysms
(but also occur with
other vascular malformations)
Subdural or epidural hemorrhages usually are
associated with ?
trauma
Most hemorrhages are due to ?
rupture of a small
intraparenchymal vessel.
accounts for roughly 15% of deaths among
individuals with chronic hypertension?
Primary Brain Parenchymal Hemorrhage
Hypertensive intra - parenchymal hemorrhages typically occur in the?
• Basal ganglia
• Thalamus
• Pons
• Cerebellum
Cerebral Amyloid Angiopathy:
1-amyloidogenic peptides deposit in the walls of medium- and small-caliber meningeal and cortical vessels.
2-amyloid confers a rigid,pipelike appearance and stains with Congo red
3-weakens vessel walls and increases the risk of hemorrhages
4-associated hemorrhages often occur in the lobes of the cerebral cortex (lobar hemorrhages).
most frequent cause of clinically significant nontraumatic subarachnoid hemorrhage is rupture of a ?
saccular (berry) aneurysm most
Other causes of Subarachnoid Hemorrhage include
• Vascular malformation
• Trauma
• Rupture of an intracerebral hemorrhage into the ventricular system
• Coagulopathies
• Tumors
Rupture of aneurysm can occur at any time, but in about
one third of cases it is associated with ?
acute increases in intracranial pressure
as with straining at stool or sexual orgasm
> > > patient is stricken with sudden, excruciatingheadache (classically described as “the worst headache I’ve ever had”) and rapidly loses consciousness
-90% of saccular aneurysms occur in the ?
anterior circulation near major arterial branch points.
atherosclerotic aneurysms frequently are fusiform and most commonly involve the?
basilar artery
الانواع الثانيه مثل الاول anterior circulation
Saccular aneurysms Due to defects in ?
the vessel media.
There is an increased risk of aneurysms in patients with?
autosomal (dominant ) polycystic kidney disease
• Aneurysms larger than……… in diameter have a roughly
50% risk of bleeding per year.
1 cm
Healing and the meningeal fibrosis and scarring sometimes obstruct CSF flow or disrupt CSF resorption,
leading to ?
hydrocephalus.
Nonsaccular aneurysms usually manifest as?
cerebral infarction due to vascular occlusion
»instead of subarachnoid hemorrhage.
Vascular malformations of the brain are classified into four principal types based on the nature of the abnormal vessels:
• Arteriovenous malformations (AVMs)
• Cavernous malformations
• Capillary telangiectasias
• Venous angiomas.
most common (most dangerous) type of vascular malformation of the brain ?
Arteriovenous Malformations
1-Associated with seizures, an intracerebral hemorrhage, or a subarachnoid hemorrhage.
2-resemble a tangled network of wormlike vascular channels.
Arteriovenous Malformations
Hypertensive Cerebrovascular Disease
1-causes hyaline arteriolar sclerosis of the
deep penetrating arteries and arterioles that supply the:
-basal ganglia
-hemispheric white matter
-brain stem
pathologic brain processes which are related
to hypertension are?
• Lacunes or lacunar infarcts
• Rupture of the small-caliber penetrating vessels
• Acute hypertensive encephalopathy
1-are small cavitary infarcts just a few millimeters in size
2-found most commonly in the deep gray matter (basal ganglia and thalamus) internal capsule, the deep white matter, and the pons.
3-caused by occlusion of a single penetrating branch of a large cerebral artery
4-Depending on their location
Lacunar Infarcts
-slitlike cavity (slit hemorrhage) surrounded by brownish discoloration?
Rupture of the small-caliber penetrating vessels
1-sudden sustained rises- in diastolic blood pressure to greater than 130 mm Hg.
2–increased intracranial pressure and global cerebral dysfunction
(headaches, confusion, vomiting, convulsions, and coma).
3-Postmortem examination show brain edema, with
or without transtentorial or tonsillar herniation.
4-Petechiae and -fibrinoid necrosis- of arterioles in the
gray and white matter
Acute Hypertensive Encephalopathy
Infectious arteritis of small and large vessels is
more often caused by ?
opportunistic infections
(such as aspergillosis, herpes zoster, or CMV)
present with a diffuse encephalopathy, often with cognitive dysfunction?
Vasculitis
diseases constitute a major cause of
mortality (death) and neurologic morbidity
(disease).
Cerebrovascular Diseases
