Topic 15-Stroke Recovery Flashcards
Diaschisis
Loss of function in remote areas anatomically connected to region of lesion (decrease in blood flow)
What does Diaschisis possibly result from?
Possibly from disruption of afferent excitatory input from lesioned area to other brain regions.
What are at least 3 separate but interactive processes associated with recovery
1) 1) Resolution of diaschisis, inflammation etc..
2) Behavioural compensation
3) Neuroplasticity
When does inflammation typically begin after ischemia, and which cells are key players?
Inflammation begins hours after ischemia, with microglia and leukocytes playing a key role by removing necrotic tissue and address secondary brain damage.
How does the resolution of core damage (umbra) affect the recovery process?
As the core damage (umbra) is resolved, the surrounding affected area (penumbra) and diaschisis effects are reduced, facilitating recovery.
What is a typical sign of an upper motor neuron lesion affecting the facial muscles?
Lower facial quadrant weakness with upper face preservation is typical of upper motor neuron lesions.
What can cause facial muscle weakness?
Facial muscle weakness can result from lesions in the facial nerve or corticobulbar tract.
How does a lesion affect facial movement on the ipsilateral and contralateral sides of the face?
The side of the face ipsilateral to the lesion can move normally, while the contralateral side may have hemiparesis
What characterizes a hemiparetic gait?
A hemiparetic gait is characterized by flexion at the elbow, wrist, and shoulder due to an imbalance between the flexor and extensor muscles.
Why does an imbalance between flexor and extensor muscles occur in hemiparesis?
The imbalance occurs because the descending motor tracts can no longer properly communicate with the rubrospinal tract, which helps regulate the balance between flexor and extensor tone.
What is neuroplasticity?
Neuroplasticity is the ability of neurons to change their function, chemical profile, or structure.
How long must changes in neurons last to be considered neuroplasticity?
Changes must be sustained for more than a few seconds to qualify as neuroplasticity and non-periodic changes
What are the three primary mechanisms of neuroplasticity implicated in stroke recovery?
) Redundancy – alternate pathways take over lost function
2) Unmasking - activation of normally inhibited pathways
3) Long-term potentiation - increasing efficiency of synaptic connections and formation of new synapses.
Can you give an example of redundancy in neuroplasticity?
For instance, in a watershed lesion affecting both motor and sensory regions, the brain might reroute signals from the damaged primary motor cortex through the premotor cortex. This allows the premotor cortex to take over and send signals down the pyramidal tract to control muscles, compensating for the lost function.
What differences in brain activation are observed in stroke patients during a motor task compared to control subjects?
Stroke patients show more diffuse brain activation in multiple areas, including the primary motor cortex and sensory areas, particularly in the unaffected hemisphere, illustrating redundancy.
How do inhibitory interneurons contribute to maintaining topographic representation in the brain?
Inhibitory interneurons prevent excitatory connections from one cortical area from activating adjacent areas, maintaining the separation between different body part representations.
What changes occur in the brain’s inhibitory patterns during stroke recovery?
During stroke recovery, changes in inhibitory patterns may occur, allowing previously suppressed areas of the brain to become active and compensate for lost functions.
How do adjacent cortical regions expand in the brain?
Adjacent cortical regions expand when preexisting lateral excitatory connections are unmasked by decreased intracortical inhibition.
What effect does a GABA antagonist like bicuculline have on the brain’s cortical areas?
Decreases the activity of inhibitory GABA interneurons, leading to disinhibition of cortical areas.
What happens to GABA receptors in response to an ischemic lesion from a stroke?
There is a reduction of GABA receptors in response to an ischemic lesion from a stroke, indicating a decrease in inhibitory signaling.
In stroke patients with left striatal capsular infarction, what neuroplastic changes are indicated by brain scans during a finger tapping task?
Brain scans indicate unmasking, shown by posterior displacement (a shift towards the back of the brain) and larger activation areas in sensory and motor regions, and redundancy, evidenced by ipsilateral and supplementary motor area activation.
What are the key features of long-term potentiation in neural function?
Characterized by the increased efficiency of synaptic connections, the formation of new synapses, and serves as a means to modify neural circuitry.
