2.16 Neuropathology: CNS Atherosclerosis Flashcards
What are the four vascular malformation of the CNS?
- Arteriovenous Malformation (AVM)
- Cavernous Angioma
- Telangiectasia
- Venous Angioma
What is a Telangiectasia?
- A focal aggregate of uniformly small vessels, with intervening neural parenchyma
- May initiate seizures, but rarely ruptures
What is a venous angioma?
- Consists of a few enlarged veins distributed randomly in the spinal cord or brain
- The lesion is generally asymptomatic.
What are Arteriovenous malformations (AVM)?
- It evolves during embryonic development which permits direct communication between cerebral arteries and veins, which gradually enlarges.
Where are arteriovenous malformations?
-The resultant conglomeration of abnormal vessels is usually located in the cerebral cortex and the contiguous underlying white matter.
What is the end result of arteriovenous malformations?
-Seizures, subarachnoid and intracerebral hemorrhages can occur in the 2nd or 3rd decades.
What is a Cavernous angioma?
Composed of large vascular spaces compartmentalized by prominent fibrous walls.
What is the end results of Cavernous angioma?
-Most remain asymptomatic, although a minority of patients have intracranial bleeding, epilepsy, or focal neurologic disturbances
What are the four types of cerebral aneurysms?
- Developmental defects- Berry Aneurysms
- Atherosclerotic Aneurysms
- Bacterial infections- Mycotic Aneurysms
- Hypertension-associated which induces interparenchymal Charcot-Bouchard Aneurysms
Define berry aneurysm and it causes?
They are caused by arterial defects that originate during embryonic development, when the bifurcation of an artery creates Y-shped configuration
Where do 90% of all berry aneurysms occur?
- Circle of Willis
1. Anterior Cerebral Artery and the Anterior Communicating Artery.
2. The complex of the Internal Carotid Artery-Posterior Communicating Artery-Anterior Cerebral Artery.
3. The trifurcation of the Middle Cerebral Artery.
Explain the pathology of berry aneurysms?
-The bloodstream from the parent vessel exerts relentless pressure on the crotch of the Y, and with time, the endothelium and internal elastic membrane degenerates and fragments.
Large aneurysms of the internal carotid complex can cause palsies in which cranial nerves?
Large aneurysms of the internal carotid complex can produce palsies of the 3rd, 4th, and 6th cranial nerves and seizures initiated by the compression of the medial aspect of the temporal lobe.
How do berry aneurysms present clinically?
- A sudden severe headache heralds the onset of the SAH and may be followed by coma.
- Patients who survive for 3-4 days often manifest a progressive decline in consciousness, due to arterial spasm and consequent cerebral ischemia and infarction.
- Survivors of the initial episode may rebleed, in which case the prognosis is worse.
Where are atherosclerotic aneurysms located?
Usually localized to the larger cerebral vessels (vertebral, basilar, and internal carotid arteries).
What is a atherosclerotic aneurysms?
-There is fibrous replacement of the media and destruction of the internal elastic membrane weaken the arterial wall and permit aneurysmal dilatation.
What is the general characteristics of an atherosclerotic aneurysms?
-Are characterisically fusiform, and elongates the vessel as they enlarge.
What are the clinical features of an atherosclerotic aneurysms?
-They rarely rupture, but the major complication is thrombosis, leading to strokes.
What is a mycotic aneurysm?
-Infections of the arterial walls that results from septic emboli, usually from an infected cardiac valve (endocarditis) that lodges itself in a branch of the middle cerebral artery.
What is Charcot-Bouchard aneurysms?
Aneurysms, associated with long-standing HTN
Where do Charcot-Bouchard aneurysms normally occur?
Occurs in a geographic distribution that closely corresponds to the pattern of intercerebral hemorrhage
What are Hypertension-Associated Aneurysms?
-The integrity of small interparenchymal cerebral arterioles is compromised by hypertension through the deposition of lipid and hyaline material in their walls (lipohyalinosis).
What happens to thin walls deep inside the brain that have a hypertension-associated aneurysm?
-The resulting weakening of the walls leads to the formation of Charcot-Bouchard aneurysms, small fusiform dilatations located on the trunk of a vessel, rather than at a bifurcation, and are predisposed to rupture, causing hypertensive cerebral hemorrhage
Where are hypertensive hemorrhages?
- The Basal Ganglia Thalamus (75%)
- The Pons (15%)
- The Cerebellum (10%)
