Causes of brain dysfunction Flashcards
Meningiomas
- tumours (neoplasms)
- grow between the meninges
- most common benign tumour
- not very aggressive in growth
- if you get rid, likely won’t come back
- encapsulated (boundary btw tumour and rest of tissue) therefore easier to remove
than infiltrating - 20% of brain tumours
- solution: open head surgery
infiltrating tumours
- malignant- more aggressive, faster growing
- grow diffusely through surrounding brain tissue
- not necessarily metastatic (spreads) but no clear delineation of where tumour begins and ends
- removal process usually also involved healthy tissue
- usually short amount of time to live
- more common
metastatic tumours
- some infiltrating brain tumours grow from tumour fragments carried to the brain from another body part via bloodstream
- commonly originates from breast or lung cancer
- very aggressive
glioblastoma/ glioma
- most common type of malignant brain tumour in adults
- very aggressive, short survival rate (12-15 months after diagnosis)
- 40% of all brain tumours
STROKE
sudden-onset cerebrovascular disorders that cause brain damage
- 2nd leading cause of death in world
common consequence: trouble speaking, coordination, confusion, disorientation, unilateral problems
infarct
- central location of stroke
- area of dead/dying tissue
- doctor isn’t interested in infarct bc dies so quickly, concerned with penumbra
penumbra
dysfunctional area surrounding the infarct
- doctor’s concern is this
- sometimes this tissue dies, not always
ischemic stroke
- clot blocks blood flow to area of brain
- extent of damage depends where is blocked
- larger clot predicts larger loss of function
hemorrhagic stroke
- blood flowing freely out of broken artery
- issue = fluid pressure on soft tissue, blood is toxic
- more dangerous
- spreads
aneurysm
- cerebral hemorrhage
- can be congenital or develop later
- commonly base of brain (circle of Willis)
- risk factors: diabetes, hypertension, smoking cigs, alc, aging
treatment options for aneurysm
- Clipping
- requires craniotomy, lower rate of recurrence than option 2
- reduces risk of rupture
- pinch at neck with titanium clip
- downside = open head surgery
short term: greater risk, long term = better efficacy - endovascular coiling: less invasive, higher rate of recurrence
- travel through arteries (leg)
- cathedra filled with platinum wire. platinum causes blood to clot (coagulation)
short term = less invasive
long term = higher rate recurrence
Cerebral ischemia
causes
- disruption of blood supply to some area of brain.
- thrombosis: a plug
- can be air bubble, fat, tumour,
plug = thrombus - embolism: moving thrombosis
- arteriosclerosis
- narrowing of arteries
- typically result of fat/cholesterol deposit
properties of cerebral ischemia
- takes while to develop (days)
- damage more likely in some parts (i.e. HPC)
- mechanisms vary btw brain structures
excitotoxicity
mechanism of ischemia-induced damage
- excessive glu release
- hard time maintaining resting membrane potential because oxygen/glucose aren’t getting to the neuron, which it needs to function (na-k pump)
- under quiet conditions, Mg2+ blocks NMDA receptors but as membrane is depolarized, Mg2+ is pushed out of cell and NMDA receptor works. under these oxygen depleted conditions, it happens excessively
- NMDA is permeable to Na and Ca (potent, triggers apoptosis in such high levels)
how to save penumbra
NMDA receptor agonists
- unfortunately doesn’t work too well. Block things that Ca signals to= cutting edge therapies for stroke
open-head injuries
- usually very severe
- high risk of infection, complications
- high velocity is worse
penetrating (through skull into brain) or
perforating (comes out other side)
-mortality = 92% (73 at the scene)
radial wound
wound travels in skull, causes lacerations
- therefore lower velocity impact is better
closed-head injury/contusion
- damage to cerebral circulatory system, producing internal hemorrhaging and a hematoma (solid swelling of clotted blood within the tissues)
contusion= bruise