Neurology and Hypoxia Quiz

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Questions and Answers

Which of the following is considered a type of hypoxia?

Hypoxic hypoxia

Anemic hypoxia

Toxic hypoxia

All of the above (correct)

What is the primary cause of cerebral infarction?

Localized area of necrosis

Rupture of cerebral vessels

Reduction or cessation of blood flow to a localized area of the brain (correct)

Inappropriate release of excitatory neurotransmitters

What is the name given to the area surrounding a cerebral infarct that is still viable but at risk of damage?

Apoptosis

Penumbra (correct)

Excitotoxicity

Necrosis

What is the characteristic gross appearance of a non-hemorrhagic infarct 2 to 19 days after the event?

Gelatinous and friable (B) Signup and view all the answers

What is the name given to the cellular change characterized by diffuse eosinophilia of neurons that are beginning to shrink?

Red neurons (A) Signup and view all the answers

Which of the following is a characteristic of a lacunar infarct?

It is typically caused by thrombosis of deep penetrating arteries. (A) Signup and view all the answers

What is a watershed infarct?

A type of infarct that occurs at the border zone of two arterial territories. (B) Signup and view all the answers

Which of the following is a common location for a lacunar infarct?

Putamen (A) Signup and view all the answers

What is a common cause of global hypoxic-ischemic encephalopathy?

Cardiac arrest (C) Signup and view all the answers

Which of the following is a hallmark of neurodegenerative diseases?

Accumulation of protein aggregates in neurons. (B) Signup and view all the answers

Which of the following is NOT a type of neurodegenerative disease?

Multiple sclerosis (D) Signup and view all the answers

How do prion diseases differ from other neurodegenerative diseases?

Prion diseases are caused by the accumulation of misfolded proteins that can spread from cell to cell. (B) Signup and view all the answers

What is the main reason behind the accumulation of protein aggregates in neurodegenerative diseases?

The proteins are not properly degraded by the cells. (A) Signup and view all the answers

Which of the following is NOT a characteristic gross finding in Parkinson's Disease?

Atrophy of the hippocampus (C) Signup and view all the answers

What is the primary role of PINK1 in the context of mitochondria?

PINK1 is a signaling molecule that recruits autophagy machinery to damaged mitochondria (A) Signup and view all the answers

Which of the following is NOT a common route of entry for infectious agents into the CNS?

Lymphatic (D) Signup and view all the answers

Which of the following is a characteristic feature of acute pyogenic meningitis?

Presence of large numbers of neutrophils in the CSF (C) Signup and view all the answers

Which bacterial species is a common cause of acute pyogenic meningitis in infants?

Escherichia coli (B) Signup and view all the answers

Which of the following is a potential mechanism by which infectious agents can damage the nervous system?

Inhibition of neurotransmitter synthesis (A) Signup and view all the answers

What is the primary difference between meningitis and encephalitis?

Meningitis affects the meninges, while encephalitis affects the brain parenchyma (D) Signup and view all the answers

Which of the following is a common cause of chronic meningitis?

Cryptococcus neoformans (B) Signup and view all the answers

What is the characteristic gross appearance of the sub-arachnoid space in tuberculous meningitis?

A gelatinous or fibrinous exudate that typically involves the base of the brain. (C) Signup and view all the answers

Which of the following is a possible cause of chronic bacterial meningitis?

Mycobacterium tuberculosis (B) Signup and view all the answers

Which of the following is a characteristic feature of the CSF in patients with tuberculous meningitis?

Clear or slightly turbid CSF which may form fibrin web on standing. (A) Signup and view all the answers

Which of the following is a common complication associated with acute pyogenic meningitis?

Waterhouse-Frederichsen syndrome (C) Signup and view all the answers

Which of the following microscopic findings is characteristic of acute pyogenic meningitis?

Dilated and engorged blood vessels. (D) Signup and view all the answers

What is the most common cause of fungal meningitis?

Cryptococcus neoformans (C) Signup and view all the answers

How does tuberculous meningitis typically spread to the central nervous system?

All of the above are possible routes of spread. (D) Signup and view all the answers

What is the typical appearance of a tuberculoma on gross examination?

A well-circumscribed intraparenchymal mass that can be several centimeters in diameter. (D) Signup and view all the answers

What characterizes the morphological changes observed in prion diseases?

Spongiform changes (A) Signup and view all the answers

Which of the following statements about Creutzfeldt-Jakob disease (CJD) is true?

The sporadic form accounts for the majority of cases. (C) Signup and view all the answers

What is the primary protein associated with the pathogenesis of prion diseases?

PrPsc (D) Signup and view all the answers

Which protein accumulations are recognized as fundamental abnormalities in Alzheimer's disease?

Aβ and tau (A) Signup and view all the answers

Which of the following describes the clinical progression of Alzheimer’s disease?

Impairment of cognitive functions is insidious and progressive. (D) Signup and view all the answers

In which decade of life is the peak incidence of familial forms of CJD observed?

Seventh decade (D) Signup and view all the answers

What type of cellular change does PrPsc facilitate in prion diseases?

Conversion of PrPc molecules into PrPsc (D) Signup and view all the answers

Which not a common sign of advanced Alzheimer's disease?

Normal cognitive function (B) Signup and view all the answers

Which type of neurosyphilis is characterized by chronic inflammation affecting the meninges and is often associated with plasma cell-rich mass lesions?

Meningovascular neurosyphilis (B) Signup and view all the answers

What pathologic finding is primarily associated with tabes dorsalis?

Loss of sensory axons in the dorsal roots (D) Signup and view all the answers

Which of the following is true regarding the CSF findings in acute aseptic meningitis?

CSF lymphocyte count is usually elevated (D) Signup and view all the answers

What characteristic finding in the CSF analysis suggests tuberculous meningitis?

Mononuclear leukocytosis with lymphocytes (C) Signup and view all the answers

Which pattern of CNS involvement in neurosyphilis is most commonly associated with significant damage to the frontal lobe?

Paretic neurosyphilis (D) Signup and view all the answers

What typical feature distinguishes chronic meningitis from acute meningitis?

Higher percentage of lymphocytes compared to neutrophils (C) Signup and view all the answers

Which of the following viruses is NOT typically associated with acute aseptic meningitis?

Mycobacterium tuberculosis (A) Signup and view all the answers

In chronic meningitis linked to neurosyphilis, what type of inflammatory cells are predominantly found in the perivascular regions?

Plasma cells (D) Signup and view all the answers

Study Notes

Pathology of the Central Nervous System

The average brain weight is ~1400 gm in men and ~1250 gm in women.
The brain is covered by three layers of membranes called meninges: dura mater (tough, fibrous outer layer), arachnoid mater (thin, intermediate layer), and pia mater (delicate, inner layer with blood vessels).
The brain surface has folds called gyri and grooves called sulci.

Outline

Introduction/Relevant Anatomy
Developmental Anomalies
Cerebral Edema, Hydrocephalus, Raised ICP & Herniation
Infections
Cerebrovascular Diseases
Traumatic Brain Injury
Degenerating Diseases
Spongiform Encephalopathy
CNS Tumor

Cerebral Edema

Excess fluid within the brain parenchyma.
May be localized or generalized.
Vasogenic edema: Due to increased vascular permeability or disruption of the blood-brain barrier.
Cytotoxic edema: Due to perturbation of normal plasma membrane permeability.
Generalized edema often combines elements of both vasogenic and cytotoxic edema.
Morphology: Flattened gyri and narrow sulci, compressed ventricles.
Causes: CNS infections, chronic lung diseases, metabolic disorders.

Complications of Cerebral Edema

Raised intracranial pressure
Herniation
Ischemic injury

Herniation

Displacement of brain tissue past rigid dural folds or through skull openings due to increased intracranial pressure.
Types:
- Subfalcine (cingulate) herniation: Cingulate gyrus of one hemisphere herniates under the falx cerebri, potentially compressing the anterior cerebral artery and causing secondary infarcts.
- Transtentorial (uncal, mesial temporal) herniation: Medial aspect of temporal lobe herniates through free margin of tentorium, potentially compressing the third cranial nerve (leading to pupillary dilation and impaired ocular movements).
- Tonsillar herniation: Displacement of cerebellar tonsils through foramen magnum, life-threatening due to brainstem compression and compromising medulla vital centers.

Hydrocephalus

Accumulation of excessive cerebrospinal fluid (CSF) within the ventricular system.
Caused by disturbance in formation, flow, or absorption of CSF.
Results in raised intracranial pressure (ICP) and ventricular dilation.
Common in children, but can occur in adults.
Causes (children): Arnold-Chiari malformations, stenosis of the aqueduct of Sylvius, Dandy-Walker syndrome.
Causes (adults): Tumors (e.g., choroid plexus papilloma), inflammation (meningitis).

Traumatic Brain Injury

Important cause of death and permanent disability in modern society.
Types of injury:
- Skull fractures: May indicate the nature of the fall. Basal fractures are commonly associated with CSF leakage from nose/ears and cranial nerve injury.
- Parenchymal injury (concussion, contusion, laceration): Transient altered consciousness due to head trauma, resulting in complete neurologic recovery. Contusions typically accompany subarachnoid hemorrhage.
- Vascular injury: Disruption of vessel walls causing hemorrhage—types include epidural hematoma (arterial blood, rapid expansion), subdural hematoma (venous blood, gradual expansion), intraparenchymal hematoma (within brain tissue), and subarachnoid hemorrhage (arterial bleed).

Cerebrovascular Diseases (CVD)

Brain injury caused by altered blood flow (ischemia/hypoxia or hemorrhage).
Stroke: Neurological signs/symptoms of vascular origin with acute onset lasting >24 hours.
Etiopathogenesis:
- Ischemia/Hypoxia: Thrombosis, embolism, hypoxia (low oxygen tension, decreased oxygen-carrying capacity, toxic substances)
- Hemorrhage: Hypertension, aneurysm, developmental malformations.
Morphology of Ischemia/Hypoxia
- Focal ischemia: Reduction/cessation of blood flow causing localized area of necrosis (cerebral infarction) and neuronal death (apoptosis/necrosis).
- Global hypoxic-ischemic encephalopathy: Generalized reduction of cerebral perfusion from cardiac arrest, diminished oxygen capacity, or shock/hypotension. Results in watershed/border-zone infarcts and lamina necrosis.
- Lacunar infarcts: Small cavitary infarcts/necrotic spaces resulting from thrombosis of deep penetrating arteries, commonly involving the putamen, globus pallidus, thalamus, internal capsule, caudate nuclei, and pons.

Neurodegenerative Disorders

Progressive loss of specific neuron groups.
Accumulation of resistant protein aggregates (tangles, plaques, Lewy bodies).

Prion Diseases (Spongiform Encephalopathy)

Rapidly progressive neurodegenerative disorders caused by aggregation & intercellular spread of misfolded proteins (prions).
Prion diseases exhibit spongiform changes and rapidly progressive dementia.
May be sporadic, familial, or transmitted.

Alzheimer Disease (AD)

Most common cause of dementia in older adults.
Insidious onset of cognitive impairment.
Pathologic hallmarks: Amyloid plaques (Aβ peptides) and neurofibrillary tangles (aggregated tau protein).
Causes neural dysfunction.

Parkinson Disease (PD)

Hypokinetic movement disorder caused by loss of dopaminergic neurons in the substantia nigra.
Protein aggregation (Lewy bodies).
Second most common neurodegenerative disorder affecting individuals ≥65 years.
Etiology includes mutations in genes encoding a-synuclein, DJ-1, PINK1, and parkin.

CNS Infections

Infectious agents damage the nervous system by direct injury, initiating an inflammatory response, or immune mechanisms.
Entry routes: hematogenous, direct implantation, local extension, and along nerves.
Types of CNS Infections: Meningitis, encephalitis, brain abscess.

Meningitis

Inflammation of the leptomeninges and CSF within the subarachnoid space.
Types include:
- Acute pyogenic (bacterial): Purulent exudate, dense neutrophil infiltration, dilated blood vessels, and edema.
- Viral (aseptic): Mild lymphocytic infiltrate in leptomeninges.
- Chronic (tuberculous, treponemal): Granulomatous inflammation, well circumscribed parenchymal masses (tuberculomas).
Clinical correlates include meningeal irritation (neck stiffness, headache), raised ICP, systemic inflammatory response (fever), and neurologic impairment (photophobia, clouding of consciousness).
Potential complications like Waterhouse-Frederichsen syndrome (adrenal hemorrhage).
Diagnostics including CSF analysis (cloudy/purulent, raised WBCs, protein, decreased glucose) and microbiological examination.

Acute Focal Suppurative Infections (Brain Abscess)

Localized liquefactive necrosis of brain tissue with accompanying inflammation, often caused by bacterial infection.

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Description

Test your knowledge on neurology concepts, particularly focusing on hypoxia and cerebral infarction. This quiz covers critical areas such as characteristics of infarcts and neurodegenerative diseases. Prepare to challenge your understanding of these crucial topics in neuroscience.