Limbic Memory Regions

l Essential for the storage of new memories

» hippocampus

» mammillary bodies & medial thalamus

l Emotional aspects of memory-

» Amygdala

l Long term memories spread thru-out cortex

Effect of Damage to Limbic Memory Regions

l Hippocampal damage – problems storing new declarative memories (semantic & episodic)

l Mammillary bodies & medial thalamus damage- memory difficulties of Korskaoff’s syndrome

l Damage to selective areas of cortex – may lose specific long term memories (like the names for things or the color of things)

l

Dementia:
More Than Memory Loss

l Cognitive deficits (in memory, reasoning, understanding, language, organization of behavior) not due to clouded consciousness

l Impaired social/occupational functioning

l Decline from previous level of functioning

l Over 100 causes; about 30% of dementias are reversible (due to endocrine problems, vitamin deficiency, medications, CSF pressure, etc.)

Most Common
Dementias

l ~50% Alzheimer’s Disease

l ~10%-25%? Dementia with Lewy Bodies & PD

l (up to 40% those with AD also have Lewy bodies)

l 15% Vascular dementia – e.g. multi-infarct dementia

l (seen in those with risk factors of stroke)

l 5-7% Pick’s Disease or fronto-temporal lobe dementia

l Other diseases causing dementia (AIDS, Huntington’s, Creutzfeld-Jakob)

Dementia with Lewy Bodies

l About 30% of Parkinson’s disease patients develop dementia. In about ¼ of these cases it is Lewy Body Dementia, in the others it is Alzheimer’s.

l Fluctuating cognitive function, visual hallucinations, extrapyramidal signs

Pick’s Disease or Fronto-temporal lobe Dementia

l 70% show unilateral degeneration, often in dom. hemisphere; microscopic Pick bodies

l Loss of restraint & personality changes before memory problems & disorientation; spatial abilities preserved

l Folstein mini mental status exam for quick assessment

Blood Supply to the Brain (see 7.2)

l 2 Internal carotid arteries on either side of the neck

l 2 Vertebral arteries on either side of the spinal column, join to form a single basilar artery on anterior surface of brainstem

l All interconnected at the “circle of Willis”

Internal Carotid Arteries

Vertebral Arteries

Circle of Willis or Circulous Arteriosus

Major Cerebral Arteries (see 7.4)

Medial View

PCA Vascular Distribution

MCA and Penetrating arteries

Angiogram (aka arteriogram)

Dural Sinus (Superior Sagittal)

Dural Sinuses (see 7.8)

Jugular Veins

Stroke or Cerebrovascular Accident (CVA)

l Death or damage of some portion of the CNS due to disruption of normal blood supply to that area

l Area of damaged/dead cells is called the infarct.

l 500,000/year in US

2 Main Varieties

l ischemic stroke - obstruction of artery deprives the tissue beyond that point of its supply of oxygen & energy (“ischemia” refers to a localized decrease in blood supply)

l hemorrhagic stroke - vessel ruptures causing both intracerebral bleeding & failure to supply blood to tissues beyond that point

Embolism

Suffering an Embolism

Thrombosis

Unhealthy blood vessels promote clot formation.

Thrombosis

Fatty Plaques in Vessels

Carotid Stenosis (narrowing)

Internal Carotid Stenosis

l Before & after balloon angioplasty

Common Treatable Risk Factors

l Hypertension (high blood pressure)

l Cigarette smoking; alcohol abuse

l Hyperlipidemia (high fats & cholesterol)

l Heart disease

l Diabetes

Treatments

l Anticoagulants to decrease risk of future clots

l “Clot-busters” like urokinase to break up a new clot

l Medications to control brain swelling

l Drugs under investigation to control neurotransmitter aftereffects of stroke

l Preventative surgeries (angioplasty, endarterectomy)

Angioplasty

Other Stroke Terms

l Transient ischemic attack (TIA)- short-term disruption of blood supply to region with reversal of symptoms within minutes to hours.

l Stroke in progress or in evolution - increasing symptoms of stroke over time. If stroke is caught early the progression of brain damage may be halted.

l Multi-infarct or vascular dementia

Hemorrhage

Intracerebral Hemorrhage (ICH) or Hemorrhagic Stroke

l Most often due to the rupturing of a small blood vessel (e.g. the penetrating arteries supplying basal ganglia, thalamus, pons, or cerebellum)

l Major risk factor : hypertension

l Others: smoking, alcohol or stimulant abuse, or use of anticoagulants.

l Accounts for 10-15% of strokes; often lethal

Intracerebral Hemorrhage

Circle of Willis

Berry Aneurysm

Arteriovenous Malformation

l Congenital malformation where arteries connect directly to veins in a little “nest” of vessels. These malformations may rupture.

Subarachnoid Hemorrhage

l Although SA bleeding may follow head injury,

“primary SAH” is usually due to the rupture of an aneurysm or AVM

» Symptoms: sudden severe headache, nausea & vomiting, fainting, signs of meningeal irritation like stiff neck & photophobia, possible seizure, LOC\

l CT scan or spinal tap to show blood

l Possible aftereffects- rebleeding, hydrocephalus, ischemia from vasospasm

Circle of Willis Aneurysm

Subarachnoid Hemorrhage

Clipping an Aneurysm

Non-Surgical Treatment

l Insert platinum coil into aneurysm to obstruct blood from entering

Warning Signs

l Sudden weakness or paralysis or numbness of lower face, arm, leg on one side

l Sudden difficulty speaking

l Sudden visual problems(blurring,loss, double)

l Sudden severe headache

l Unexplained dizziness, unsteadiness, falls – especially with 1 of above signs

Symptoms of Stroke

l Depend on particular blood vessel affected and the site and extent of brain damage

» Large vessel strokes (e.g. one of the cerebral arteries) affect multiple areas

» Small vessel or lacunar strokes more limited – may even go un-noticed until you have several

Patterns of Stroke Deficits

l MCA – Contralateral motor & sensory problems of upper body, aphasia (L), neglect

l ACA – Prefrontal symptoms, incontinence, motor & sensory problems in opposite leg

l PCA- Cortical blindness; visual agnosias

l Basilar – brainstem symptoms: nystagmus, vertigo, eye control probs,dysphagia, dysarthria, ataxia, possible locked-in syndrome

Small Vessel Stroke

l Occlusion of small vessels produces a smaller area of ischemia and infarction

l Small infarcts are often called “lacunae”

l Common locations: internal capsule, basal ganglia, thalamus, brainstem.

l Really small lacunar strokes may go un-noticed.