Stroke & Recovery Flashcards
Stroke: haemorrhage
Bleeding, weak vessels rupture
Aneurysm and AVM
Stroke: isechemia
Thrombosis - develops at clogged section
Cerebral embolism - travels
Atherosclerosis - cholesterol / fatty deposits
Stroke : transient isechemic attacks
Warning, temporary
Less than 5 minutes
Local stroke
Infarcts
Cell death due to lack of oxygen and nutrients
Local stroke
Penumbra
Region around infarcts
Suffered loss of blood but tissue is still alive
Distant stroke effects
Diaschesis
Damage in one brain area extends to distant areas
Experimental stroke
MCAO
Middle Cerebral Artery Occlusion model
No surgery, stimulates clot
Remove after 30-120min to create spontaneous reperfusion
Damage in MCA, sensory & motor complications
Used in rats
Number of strokes in a year
150,000
Number disabled by a stroke in a year, UK
450,000
Stroke : common death?
3rd most common cause of death
Who is more affected by strokes?
Women more likely to die
Men have a higher risk of stroke
South Asian/Afro-Caribbean increased risk
Risk factors for stroke
Heart disease
Smoking
High blood pressure
What happens in a stoke?
Neurons are deprived of nutrients and oxygen
Permanent damage after 2mins
Apoptopic and necrotic cell death
MCA
Middle Cerebral Artery
Supplies motor and speech areas
Stroke recovery
Rehabilitation
Nudo et al (96)
Monkey - Lesion in part of hand representation
Retrained hand use
Expansion of representation depended on use/training
Undamaged MC important
Stroke recovery
Rehabilitation
Libert et al (00)
Humans stroke SS
Unaffected arm restrained for 8h a day for 12days
Sig recovery compared to before therapy
Sig enlargement of limb in injured hemisphere
Stroke recovery
Remapping remote areas
Frost
PMC is connected to the ventral PMC: access to spinal cord and motor
Frost - ICMS to map hand in M1 and PMv, Focal isechemic lesion in M1 12w monitor, then remapping M1 representation decreased, PMv increased (proportionate) PMv took over motor function
Stroke recovery
Time periods
Biernaskie et al (04)
Animal study, enriched rehabilitation effective immediately
MCAO given to rats, rehab after 5/14/30days
Sooner = better recovery
14/15days sig recovery
More dendritic branches and longer at 5days
Stroke recovery
Time periods
Horn et al (05)
5x US facilities
n830 post stroke rehabilitation SS
Sooner & more challenging the rehab - better outcome
Even in low functioning SS
Stroke recovery
Redundancy
Alternative mechanisms
Stroke recovery
Contra lateral pathways
Sensory and motor organisation connect each hemisphere via corpus callosum - function could be supported by another area
Stroke recovery
Remapping
“Wake” the penumbra by remapping connections
Limited time, activity dependent
Stroke recovery
Remapping
Glees & Cole (59)
Electrodes: thumb representation damaged but reappeared in penumbral area
ICMS
Intracranial Micro Stimulation
Stroke recovery
Remapping
Nudo & Milliken (96)
ICMS mapped forelimb movement in squirrel monkey
Created isechemic infarct
Deficit in contralateral hand
Remapped later: increase in adjacent representations
Lost movement didn’t reappear in adjacent cortical regions
Stroke recovery
Remapping
Cramer et al (06)
N15
Good stroke recovered humans
fMRI on surrounding cortical infarct
Activity present, but less than controls