Download stroke - UCSD Cognitive Science

STROKE
Vascular System
• Reminder: All brain function is dependent
on oxygen.
• There are two main arterial supplies to the
brain:
– Carotid Arteries
– Basilar Artery (comes off of vertebral arteries)
Identify the following arteries
in the cerebral angiogram in
the image above: Vertebral
Artery - Basilar Artery
Vertebal Arteries/Basilar Artery
Right Internal Carotid Artery
Stroke
• Reduction in or disruption of Blood Flow to
the brain
• Two major categories:
– Ischemic (blockage of artery)
– Hemorrhagic (damage or tear in artery)
A side category:
• TIA or Transient Ischemic Attack.
• Typically involves small emboli in an artery that
resolves rapidly.
• Thus, the physical or cognitive effects typically
resolve within an hour to 24 hours.
• There is rarely persistent damage following a TIA
• TIAs are often a signal of an impending stroke.
Mechanisms of Brain Damage
• Excitotoxic Cell Death
– Via excitatory amino acid release
– Excess calcium flow
– Free-radical release, etc.
PARP (enzyme involved in cell repair via ATP
turnover) – excess ATP turnover – cell death.
Pnumbra (excess damage or halo surrounding
vascular damage).
“Stroke”
• Often viewed as motor and speech
phemomenon – due to the prevalence of
middle cerebral artery stroke.
• Stroke can occur in any location and
symptoms will map onto the brain region
that has undergone O2 deprivation.
Medical Issue
• Physical Deficits rather than cognitive
deficits attract the most attention after
stroke.
• Physical rehabilitation is readily prescribed.
• 50-75% of stroke patients have persistent
cognitive impairments after stroke.
Clinical Issues to Resolve
• Obviously, the cognitive problems associated with
stroke are going to vary in relation to the region.
• Damage to certain cortical targets may generate
notable cognitive signs: amnesia, alexia, agraphia,
apraxia, agnosia, etc.
• These signs often exist alongside “non-cognitive”
signs such as emotional instability or loss of
initiative.
• There is often depression following stroke. It is
difficult to disentangle the axis of depression from
that of cognitive dysfunction.
Vascular Dementia or Multi-Infarct
Dementia
• Accumulated Cortical Infarcts
Distributed across cortical networks
• Strategic Subcortical Infarcts
– Generally disconnect the prefrontal cortex from the
thalamus or basal ganglia (thalamus + BG and/or genu
of internal capsule, etc.
• Cortical disconnection syndrome
– Often white matter lesions (associated with
hypofunction of cortical regions as well).
The Classic Case of the Rt. MCA
CONCLUSION
• Vascular incidents must be carefully
followed, to prevent recurrence.
• Multiple vascular events may result in a
dementia complex.
• Both physical and occupational/cognitive
therapy are important in promoting
remapping following stroke.