Neuroscience Quiz on Cerebral Edema

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Questions and Answers

What is the primary cause of vasogenic cerebral edema?

Disruption of neuronal function due to ischemia

Increased capillary permeability allowing fluid to accumulate (correct)

Obstruction of cerebral spinal fluid drainage

Increased intracranial pressure from external trauma

Which of the following conditions is primarily associated with cytotoxic cerebral edema?

Ischemia of neuronal and glial cells (correct)

Increased cerebrospinal fluid pressure

Meningitis leading to infection

Traumatic brain injury

What occurs during Stage II of cerebral autoregulation?

The body compensates for low blood flow to the brain

Vasodilation occurs to increase cerebral blood flow

Blood flow is diverted from the cerebral arteries

Intracranial pressure becomes excessively high leading to systemic hypertension (correct)

What is a consequence of Stage IV in cerebral autoregulation?

Herniation of brain tissue leading to severe ischemia Signup and view all the answers

What are the distinguishing histopathological features of Alzheimer’s disease?

Presence of plaques and neurofibrillary tangles Signup and view all the answers

What is the role of β-Amyloid protein in neurons as noted in Alzheimer’s pathology?

It plays an undefined role in nerve cell development Signup and view all the answers

Which of the following is NOT a symptom of increased intracranial pressure (ICP)?

Increased heart rate Signup and view all the answers

What is interstitial cerebral edema primarily caused by?

Hydrostatic pressure increases within the cerebrospinal fluid Signup and view all the answers

What is the primary goal of treatment for traumatic brain injury?

To minimize secondary injury and salvage brain cells Signup and view all the answers

Which type of brain injury involves an uninterrupted dura?

Closed Head Injury Signup and view all the answers

What commonly follows the initial brain injury, potentially leading to greater damage?

Secondary injury due to ischemia and edema Signup and view all the answers

Which condition describes the injury that is localized at the site of impact?

Contusion Signup and view all the answers

What is a characteristic of severe axonal injury?

Impaired brainstem function with high mortality Signup and view all the answers

In the context of cerebrovascular accidents, what is an embolic stroke?

A stroke resulting from a distant fragment traveling to the brain Signup and view all the answers

Which of the following symptoms might accompany a contusion?

Loss of consciousness lasting 24 hours Signup and view all the answers

What immediate action is crucial following an ischemic stroke?

To restore perfusion as quickly as possible Signup and view all the answers

What is primarily affected by the overproduction of tau protein in Alzheimer’s disease?

Formation of microtubules Signup and view all the answers

Which stage of Alzheimer's disease is characterized by mild confusion that is often hidden from others?

Stage 3 Signup and view all the answers

What does the presence of neurofibrillary tangles and plaques in the brain indicate?

Underlying enzyme deficiencies Signup and view all the answers

In Alzheimer's disease management, what was the initial class of drugs employed?

Anticholinesterase agents Signup and view all the answers

Which brain regions are primarily affected by Alzheimer’s disease, resulting in atrophy?

Cortex and hippocampus Signup and view all the answers

Which stage of Alzheimer's includes the inability to recall learned tasks such as driving?

Stage 4 Signup and view all the answers

What is a possible outcome of the Alzheimer's disease progression after several years?

Inability to perform activities of daily living Signup and view all the answers

What is the typical time frame over which Alzheimer's disease may progress through stages?

12 years or more Signup and view all the answers

What describes the primary cause of a seizure?

Abrupt excessive discharge of electrical impulses from neurons Signup and view all the answers

What characterizes partial (focal) seizures?

They originate from cortical neurons in one hemisphere Signup and view all the answers

What is a common consequence of increased pressure in the spinal canal due to injury?

Decreased sensation in the lower body Signup and view all the answers

What type of stroke results from a vascular malformation?

Hemorrhagic stroke Signup and view all the answers

What occurs during a generalized seizure?

Multiple subcortical foci generate spontaneous discharges in both hemispheres Signup and view all the answers

What is the main characteristic of spinal shock?

Complete loss of reflexes and flaccidity Signup and view all the answers

What triggers the change in neuronal environment leading to seizures?

Altered neurotransmitter balance Signup and view all the answers

What is a significant consequence of neurogenic shock?

Bradycardia and hypotension Signup and view all the answers

What condition may arise from injuries above T6?

Autonomic dysreflexia Signup and view all the answers

What happens during the hemorrhagic conversion of an ischemic stroke?

There is a bleeding event following an ischemic episode Signup and view all the answers

What type of stroke is characterized by spontaneous bleeding in the brain?

Hemorrhagic stroke Signup and view all the answers

What treatment is recommended for autonomic dysreflexia?

Elimination of the irritating stimuli Signup and view all the answers

What effect does elevated intracranial pressure typically have on a patient?

Unresponsiveness and possible respiratory failure Signup and view all the answers

What is the primary function of cerebrospinal fluid (CSF) in relation to the brain and spinal cord?

To provide buoyancy and cushion against impacts Signup and view all the answers

According to the Monroe-Kellie Doctrine, what must occur if there is an increase in the volume of one component in the skull?

The volume of another component must decrease Signup and view all the answers

Where is cerebrospinal fluid (CSF) primarily produced?

In the lateral, third, and fourth ventricles Signup and view all the answers

What is the typical volume of cerebrospinal fluid circulating around the brain and spinal cord at any given time?

125 – 150cc Signup and view all the answers

What is the anatomical significance of cisterns in relation to CSF?

They are openings of the subarachnoid space due to separation of meninges Signup and view all the answers

How does cerebrospinal fluid (CSF) flow through the brain's ventricular system?

From the lateral ventricles to the third ventricle and then to the spinal cord Signup and view all the answers

What is a primary role of the arachnoid villi in the cerebrospinal fluid (CSF) system?

To facilitate the reabsorption of CSF into the venous circulation Signup and view all the answers

What impact does an increase in intracranial pressure (ICP) have on the components within the skull according to the Monroe-Kellie doctrine?

It necessitates a reduction in the volume of either brain or blood Signup and view all the answers

Study Notes

Lecture Hall Timeline

1:30-2:15: PollEv questions and focused review
2:20-3:05: Group meeting, work on case/questions
3:05-3:15: Break
3:15-4:15: Review case/questions, submit assignment
4:20: Class ends

Questions & Review

A&P: Brain & Spinal Cord, Cerebral hemodynamics, CSF & ICP, Delirium & Dementia, Brain Injury (CVA, TBI), Seizures
Group Work: Spinal Cord Injury (neurogenic & spinal shock, autonomic dysreflexia), Intracerebral hypertension (cerebral edema, ICP)

Cerebral Hemodynamics

Monroe-Kellie Doctrine: The brain, blood, and cerebrospinal fluid are contained within the rigid skull. Increasing the volume of any one component results in increased intracranial pressure (ICP). To maintain normal ICP, the volume of one component must decrease.
Brain: 80%
Blood: 10%
CSF: 10%

Cerebrospinal Fluid (CSF)

CSF provides buoyancy to protect the brain and spinal cord.
Approximately 125-150 cc of CSF circulates around brain and spinal cord, with 75 cc inside intracranial space.
Produced in the choroid plexus in ventricles of the brain.
CSF flows from the lateral ventricles, through the cerebral aqueduct, and into fourth ventricle.

CSF exerts pressure

CSF flow results from pressure gradient between the arterial system and CSF-filled cavities.
CSF flows from lateral ventricles through third ventricle, cerebral aqueduct, fourth ventricle, pontine cisterns, and cerebromedullary cistern & into subarachnoid space of brain and spinal cord.
A cistern is an opening of subarachnoid space, created by a separation of arachnoid and pia mater.

Arachnoid villi

Arachnoid villi are one-way valves that open at a pressure gradient of 5 mmHg; closer and stop allowing flow backward.
Flow stops when the pressure gradient is less than 5 mmHg.
CSF ultimately drains into jugular system for return to the heart.

Lumbar Puncture

CSF samples can be taken using lumbar puncture, into the space between third & fourth lumbar vertebrae.
Sample evaluation: discolouration (3 hours after SAH), WBC (0-5 cells/mm3 normal), protein (15-45mg/100 ml normal), glucose (60-100mg/100 ml or 80% of blood glucose normal)

Intracranial Pressure (ICP)

Normal ICP is 5-15 mmHg.
Can be increased by: increased brain volume (tumor, hematoma, edema, abscess, infection), increased blood volume (increased arterial flow, decreased venous drainage), increased CSF volume (hydrocephalus from increased production, obstruction to flow)
If autoregulation is overwhelmed, ICP rises more rapidly, causing brain herniation into the brainstem and inevitable brain death.

Cerebral Edema

Vasogenic: Increased capillary permeability, water and proteins move from intravascular space to extravascular space; blood brain barrier disrupted by direct injury, tumor, or inflammation.
Cytotoxic: Neuronal, glial, & endothelial cellular swelling due to loss of Na⁺ and K⁺ pump function; usually from ischemia.
Interstitial: Increased fluid in periventricular white matter due to increased CSF and hydrostatic pressure.

Cerebral Autoregulation

Stage 1: Vasoconstriction to decrease blood flow into the brain.
Stage 2: ICP becomes too high to compensate with vasoconstriction; systemic hypertension occurs to force adequate blood upward.
Stage 3: ICP rises to almost equal arterial pressure, leading to brain tissue ischemia, inflammation, and edema.
Stage 4: Increased pressure in the cranial vault causes brain herniation, with increased ischemia, obstructive hydrocephalus, and cessation of systemic and cerebral blood flow.

Clinical Signs & Symptoms of Increased ICP

Infants: Tense/bulging fontanel, separated cranial sutures, increased occipital circumference, tense scalp veins, changes in feeding, crying when disturbed, setting-sun sign
Children: headache, nausea, vomiting, diplopia, blurred vision, seizures

Delirium vs. Dementia

Delirium: Acute, often dramatic onset; global amnesia; waxing and waning severity; often reversible
Dementia: Gradual onset; selective amnesia; sun-downing; often irreversible; EEG shows normal baseline unless advanced.

Alzheimer's Disease

First diagnosed in 1906 by Dr. Alzheimer.
Characterized by:
- Extraneuronal Beta-amyloid plaques: cluster of beta-amyloid protein due to enzyme deficiency or genetic mutation
- Intraneuronal Tau protein neurofibrillary tangles: due to lack of enzyme or genetic defect, causes overproduction of tau protein.
- Acetylcholine deficit
Most likely a combination of 3 factors: neuron death & inflammation, brain atrophy (esp. cortex & hippocampus), and enlargement of ventricles.
Stages of Alzheimer's progress over 12+ years: Stage 1 (no deficits), 2 (mild cognitive deficits), 3 (mild confusion), 4 (inability to do financial work), 5 (requires assistance), 6 (lacks past & present awareness), 7 (limited speech & movement)

Alzheimer's Disease Management

Initial treatments (anticholinesterases) only cause a temporary change in the disease's progression.
New treatments are examining critical steps in plaque and tangle formation.

Focal Brain Injury

Contusion: Injury at the point of impact and rebound sites, injured blood vessels in the area causing hemorrhage, infarction, necrosis, and edema. Symptoms vary with severity. Can include loss of consciousness, brief loss of reflexes, loss of respiration, bradycardia, and hypotension.
Hematoma: Bleeding between dura and skull (epidural), between dura & arachnoid (subdural), within brain parenchyma (intracerebral).
Severity of hematoma and secondary injury impacts symptoms.

Diffuse Axonal Brain Injury (DAI)

Widespread damage to axons with associated tissue tears due to shearing forces from deceleration.
Not immediately visible on CT, but may be visible on MRI 12 hours to several days later.
Severity levels based on coma duration and brainstem function: Mild (coma 6-24 hours), moderate (coma > 24 hours), severe (impaired brainstem function, high mortality).

Primary vs. Secondary Injury

Primary: immediate injury from direct impact (focal, diffuse)
Secondary: delayed damage from ischemia, edema, inflammation, neuronal loss, resulting in longer-term consequences.

Cerebrovascular Accidents (CVAs)

Classified as ischemic or hemorrhagic
Ischemic: Thrombotic (clot), Embolic (traveling clot), global hypoperfusion/anoxia; treatment focuses on restoring perfusion.
Hemorrhagic: Intracerebral hemorrhage, intracranial, subarachnoid; treatment manages pressure and secondary tissue injury.

Ischemic Stroke

No matter the cause, the initial injury leads to an 'ischemic core' and a 'penumbra' (surrounding tissue at risk).
Treatment: Thrombolytic therapy (like t-PA), or mechanical clot removal.

Hemorrhagic Stroke

Hemorrhage can arise due to: Spontaneous, hemorrhagic conversion of an ischemic stroke, vascular malformation.
Increased pressure and secondary tissue injury are a major concern.

Seizures

Abrupt excessive discharge of impulses in cortical neurons, disturbing excitation/inhibition of impulses.
Focal vs. generalized
- Focal: originate within one hemisphere and remain confined. Different focal areas can lead to different symptoms
- Generalized: involve multiple subcortical foci from both hemispheres.

Types of Seizures

Simple Partial: Awareness retained, sensory/motor/autonomic symptoms
Complex Partial: Altered awareness, may involve autonomic symptoms and/or psychomotor phenomena
Absence: brief, staring episode
Tonic-Clonic (Grand Mal): Loss of consciousness, stiffness (tonic), jerking movements (clonic)
Myoclonic: sudden, brief muscle jerks
Atonic: sudden loss of muscle tone.

Causes of Seizures

Neurodegenerative disorders
Genetic factors
Hypoxic-ischemic causes
Metabolic issues
Conditions leading to space-occupying lesions (e.g. tumors, trauma, infection)
Brain trauma

Spinal Cord Injury

Results in both primary (immediate) and secondary (delayed) injury.
Primary: impact that directly damages the spinal cord tissue
Secondary: ischemia, edema, inflammation, and neuronal loss.
Increased pressure within the spinal canal plays a destructive role.

Level of Injury: Sensory & Motor Deficits

Myotomes: muscle groups controlled by specific segments of spinal cord
Dermatomes: areas of skin innervated by specific spinal nerves

Incomplete Spinal Cord Injuries

Different types result in variable degrees of sensory and motor loss.
- Brown-Sequard Syndrome: paralysis/weakness on one side of the body with loss of sensation on opposite side
- Anterior Cord Syndrome: loss of motor function and pain and temperature sensation. Often from compression.
- Posterior Cord Syndrome: loss of pain, temperature, vibration, and position sense. Often from compression.
- Central Cord Syndrome: greater motor impairment in the upper body, with variable sensory loss; common in cervical spine injures

Neurogenic vs. Spinal Shock

Spinal Shock: Complete loss of reflexes and flaccidity. May persist for days to 3 months, then hyperreflexia and spasms.
Neurogenic Shock: Occurs in cervical or upper thoracic injuries. Loss of sympathetic tone, causing parasympathetic predominance: bradycardia, hypotension, and hypothermia

Autonomic Dysreflexia (AD)

Life-threatening hypertensive crisis.
Stimuli from below injury level (e.g. pain, full bladder/bowel) triggers massive sympathetic response: widespread vasoconstriction, causing dangerous hypertension.

Intracranial Hypertension (ICH)

Increased pressure inside the cranial vault by a variety of events
Manifests clinically through a number of symptoms relating to the pressure on the underlying brain structure and/or its vessels

Group Work Part II & III Questions

The provided cases are clinical scenarios, and the specific answers require analysis of medical information. The notes provided will be helpful to formulate accurate responses to the questions.

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Description

Test your knowledge on cerebral edema and its mechanisms in this neuroscience quiz. Delve into the intricacies of Alzheimer's disease, cerebral autoregulation stages, and the symptoms of increased intracranial pressure. Perfect for students studying advanced neurobiology concepts.