Neuroscience Quiz on Cerebrovascular Accidents

CNS Vascular System

• The central nervous system (CNS) is composed of grey matter and white matter
• Grey matter is the outer layer of the brain, containing cell bodies
• White matter contains axons with myelin, crucial for functioning
• Both grey and white matter are essential parts of the brain and spinal cord
• Grey matter's color comes from the high concentration of neuronal cell bodies

Neurons

• Neurons have dendrites, a nucleus, a soma (cell body), axons, and axon terminals
• Myelin sheaths surround the axons
• Multiple sclerosis is a condition where myelin sheaths break down

CNS Circulation

• Two paired arteries supply blood to the brain: vertebral and internal carotid arteries
• These arteries ascend from the neck to the cranium
• Terminal branches form the Circle of Willis, an anastomotic circle
• The Circle of Willis supplies blood to much of the cerebrum
• Smaller branches from the vertebral arteries supply parts like the pons and spinal cord

Arterial Circle of Willis

• The terminal branches of the vertebral and internal carotid arteries form the circle
• This circle is vital for blood flow
• Components include anterior and middle cerebral arteries, posterior cerebral arteries, and connecting anterior and posterior communicating arteries.
• Middle cerebral artery (MCA) is most commonly affected in stroke

Blood Supply to the Cerebrum

• Three cerebral arteries (anterior, middle, and posterior) supply different parts of the cerebrum
• Anterior cerebral arteries supply the lower limbs’ motor and sensory areas
• Middle cerebral arteries supply the upper limbs, face, Broca's area (in dominant frontal lobe), and Wernicke's area (in dominant temporal lobe)
• Posterior cerebral arteries supply the occipital lobe and parts of the temporal lobe, including the visual cortex

Blood-Brain Barrier

• Blood vessels in the central nervous system have unique properties creating the blood-brain barrier (BBB)
• The BBB tightly controls the movement of ions, molecules, and cells between blood and brain
• This control ensures proper neuronal function and protects neural tissue from toxins, pathogens, inflammation, and disease
• The BBB can be an obstacle for drug delivery to the CNS

Cerebral Vascular Accident (Stroke)

• The brain is sensitive to oxygen starvation
• A stroke is an acute neurological deficit due to blood supply disruption
• Causes include thrombosis (local blood clot), embolism (blood clot elsewhere), hypoperfusion (low blood pressure), and hemorrhage (blood accumulation)
• Embolism is the most common cause, often stemming from neck vessels

Intracerebral Aneurysms

• An aneurysm is a bulge or dilation of an artery larger than 50% of normal size
• Aneurysms often originate in vessels contributing to the Circle of Willis blood supply
• These are usually asymptomatic until they rupture
• Rupture causes blood to accumulate in the subarachnoid space, leading to increased intracranial pressure
• Rupture is a life-threatening emergency requiring surgical intervention

Cerebrospinal Fluid (CSF)

• CSF is a clear, colorless body fluid found in the brain and spinal cord
• It's produced by ependymal cells in the choroid plexuses of the brain ventricles and absorbed by arachnoid granulations
• CSF functions to keep the brain buoyant (“shock absorber”), deliver nutrients and remove waste, and flow between the cranium and spine to compensate for intracranial pressure changes

CSF Circulation

• CSF flows through the ventricles connected by narrow passages, exiting into cisterns on the brain's base
• It bathes brain and spinal cord surfaces, then re-enters the bloodstream

CSF Pressure

• Intracranial pressure (ICP) is the pressure inside the skull and, thus, the brain tissue and CSF
• Measured in millimeters of mercury (mmHg)
• Normal ICP, at rest, ranges from 7-15 mmHg

Hydrocephalus

• Hydrocephalus is a condition where the balance of CSF production and absorption is disrupted
• Congenital or acquired, it can disrupt the flow in communicating vs non-communicating ways

Ventriculoperitoneal Shunt (VP Shunt)

• A shunt allows CSF drainage from the brain to another part of the body
• Often a permanent or semi-permanent surgical procedure
• Necessary for growth, infection or other conditions

External Ventricular Drain (EVD)

• A temporary drainage device for collecting CSF
• Often done as an alternative or intermediary to VP shunts

Motor Learning

• Motor learning, occurs throughout life, if the environment changes the central nervous system (CNS) has plasticity
• Learning new movements, like walking on varied terrains, involves a process with cognitive, associative, and autonomous stages
• The brain can re-adapt and relearn skills despite damage
• The process of acquiring new motor skills or relearning lost ones

Feedback

• Intrinsic feedback is inherent to the body (e.g., sensory, visual, proprioceptive, and tactile/somatosensory).
• Extrinsic feedback is augmented/provided by external sources (e.g., verbal and manual).

Practice of Motor Skills

• Techniques for practicing motor skills include Whole (practicing all steps together), Pure Part (practicing steps in isolation — forward or backward), and Progressive Sequential (teaching parts sequentially). A combination of methods (Whole-Part-Whole, for example) might be useful

Practice Schedules

• Practice scheduling considers factors like constant, variable, or intermittent patterns
• Practice is often done independently or with caregiver help

Summary of Motor Learning Context

• Motor skills evolve to meet a patient's need to interact with the environment
• Functional skills support activities like work, play, and leisure

Additional Notes

• The provided text discusses various aspects of the Central Nervous System (CNS), especially the vascular system and motor learning. The detailed study notes accurately cover important concepts and procedures.