Stroke Flashcards
How does stroke happen?
Block or a bleed
Sleep, epilepsy and migraine all relate to alterations in….
NEUROEXCITATION
What is a block stroke?
Occlusive, ischaemic stroke
Atherosclerotic or thrombotic occulsion of a blood vessel that feeds the brain. Vascular narrowing. Blood clots
What is a bleed stroke?
Hemorrhagic stroke
Bleeding from blood vessel in brain
Chronic hypertension, head trauma, coagulation disorders, brain tumours, aneurism, preeclampsia, cocaine or amphetamine abuse.
What are major risk factors for stroke?
Oral contraceptive pill
Smoking
Migraines
Blood clot formation.
Warning signs of stroke?
Numbness of body, especially just one side.
Confusion of speech
Seeing difficulties
Loss of balance
Sudden headache
What leads to uncontrolled action potentials?
Failure to maintain resting potential
- high na and ca on the OUTSIDE
- high k and anions on the inside
- maintained by pumps and channels
- need energy via blood needed to maintain this
- no energy=increase intracel na=swelling and APs
What does sustained neuronal activation lead to?
- neurotransmitter release
- further neuronal activation
- disruption of ionic gradients especially calcium
- neuronal stress and cell death
What controls calcium concentration levels?
Na-ca exchanger
If sodium gradient dissipates calcium is oumped in reverse into the cell!
What does excessive calcium do?
-proteases (calpain-essential for necrosis)
-phospholipases (PLA2-cleaves bonds in membrane fatty acids and phosphate head groups)
-nitric oxide synthase
Inhibits NADH ubiquitinone oxidoreductase and NADH succinate (important for metabolism)
Forms peroxynitrate (FREE RADICAL DAMAGE) to membranes and compounds with sulfhydryl groups
How does acidosis occur?
Interuption to cerebral blood flow leads to increased co2 tension
More co2 means more lactic acid
What does acidosis do?
Promotes free radicals, inhibits na-ca exchanger, activates acid sensing ion channels
May be neuroprotective? As only some neural damage can occur at neutral pH, may be due to NMDA channel inhibition.
What are treatments for ischaemic stroke during first 3 hours?
Thrombolytics
rtPA tissue type plasminogen activator aka ALTEPLASE
- promotes conversion of proemzyme plasminogen to plasmin
- degrades fibrin peptides in blood clots
What is long term treatment for stroke?
Anticoagulants
Asprin, clopdigrel, dypridamole, warafin, apixiban
What is the treatment for hemorrhagic stroke?
Surgery to stop the bleed
Hyperosmotic agents to reduce swelling
Long term antihypertensives to redice blood pressure against weak vasculature
