Chap 28 Key Concepts Flashcards
What is a feature of injury in the nervous system?
There is a distinct set of patterns of response to the injur
What are the characteristics of neuronal injury?
- Cell death by apoptosis or necrosis
- Loss of neurons (difficult to detect)
What is the morphology of an injured astrocyte?
- Hypertrophy of the cytoplasm
- Accumulation of intermediate filament protein (GFAP)
- Hyperplasia
What are microglia?
Resident monocyte-lineage population of the CNS
How does microglia react in response to injury?
Proliferate and accumulate
What is cerebral edema?
Accumulation of excess fluid within the brain parenchyma
What is hydrocephalus?
Increase in CSF volume within all or part of the ventricular system
What can raise the pressure inside the fixed capacity of the skull?
Increases in volume of the intracranial contents Ex. increase of CSF volume Ex. edema Ex. hemorrhage Ex. tumor
How does increase in pressure relate to perfusion?
increased pressure can cause decreased perfusion which leads to ischemia
How do herniations occur?
increased pressure displaces tissue past the edges of dural partitions inside the skull or through openings in the skull
What can cause malformations in the CNS?
Single gene mutations, larger scale genetic alterations, exogenous factors
What stage of development is a malformation likely to be most severe?
The earlier in development of a malformation, the more severe
How does a neural tube defect occur?
Failure to close or inappropriate reopening of the developing neural tube
How does cortical development occur?
Proper progenitor cell proliferation in germinal matrix and migration of progenitors upward into developing cortex
What is the result of disruption of cortical development?
Alters size, shape and organization of the brain
Why is time so critical in a perinatal brain injury?
The earlier events cause greater damage and deficits
What is cerebral palsy?
Non-progressive deficits with injury during the prenatal and perinatal periods
How does physical injury to the brain occur?
When inside the skill comes into forceful contact with the brain
When and how do coup and countrecoup injures occur?
- Occurs with blunt trauma
- If the head is mobile, there is injury at the original point of contact (coup) and on the opposite side of the brain (countrecoup)
How do parenchymal injuries occur?
In the form of a contusion with hemorrhage extending into the subarachnoid space
How does diffuse axonal injury occur?
Rapid displacement of the head and brain that tears the axons
What can traumatic tearing of blood vessels cause?
Epidural and subdural hematomas
What is a stroke?
Clinical term for acute-onset neurologic deficits resulting from hemorrhagic or obstructive vascular lesions
When does cerebral infarction occur?
- Following the loss of blood supply
- Can be widespread or local or affect regions with the least robust vascular supply
How does a focal cerebral infarct usually occur?
Following dissolution of an embolism and reperfusion
What can cause a primary intraparenchymal hemorrhage?
- Hypertension (in white matter, deep gray, posterior fossa contents)
- Cerebral Amyloid Angiopathy
What is the usual cause of a spontaneous subarachnoid hemorrhage?
A structural vascular abnormality
Ex. Aneurysm or arteriovenous malformation
What are the various routes used by an organism to get access to the brain?
- Hematogenous spread- abscess formation
- Direct extension- after trauma or from sinuses
- Retrograde transport along nerves
What route by the organism is used in Rabies
Retrograde transport along nerves
What infections are caused by bacteria involving the CNS?
Meningitis, cerebral abscesses, chronic meningoencephalitis
What infections are caused by viruses involving the CNS?
Meningitis or meningoencephalitis
What is the characteristic pattern of HSV-1 infection in the CNS?
Pattern in the temporal lobes
What is the characteristic pattern of Polio in the CNS?
Pattern in anterior horn
How does HIV directly and indirectly affect the brain?
Directly- cause meningoencephalitis
Indirectly- increasing risk of opportunistic infection (toxoplasmosis, CMV)
How do prion diseases occur?
Conversion of normal protein PrPc into abnormal conformation PrPsc
What is specific about the familial form of prion diseases?
Linked to mutations in PrPc gene (PRNP) which determine the phenotype
What is the disease phenotypes for CJD?
Rapidly progressive dementia
What is the disease phenotype for Gerstmann-Staussler-Scheinker syndrome?
Progressive cerebellar ataxia
What does loss of myelin in demyelinating diseases cause?
Widespread and severe neurologic deficits
What occurs in a demyelinating disease?
Breakdown and destruction of normal myelin
What is Multiple Sclerosis?
Autoimmune demyelinating disease that affects young adults
What is the pattern of clinical presentation of MS?
Relapsing-remitting course with progressive accumulation of neurologic deficits
How are neurodegenerative diseases characterized?
By progressive neuronal loss involving specific neuronal circuits and brain regions
- Mostly associated with abnormal protein aggregates
What reflects the pattern of the brain in neurodegenerative diseases?
Clinical phenotype
What are groups of neurodegenerative diseases?
- Grouped by clinical presentation: Dementias, hypokinetic movement disorders, hyperkinetic movement disorders, cerebellar ataxias, and motor neuron diseases
What is the most common type of dementia and what occurs?
AD- with plaques of Ab and tangles of tau
What do the lesions of Dementia with Lewy bodies contain?
alpha-synuclein
What is the most common hypokinetic disorder?
Parkinson disease
- Contains alpha-synuclein inclusions
What diseases have parkinsonism as a symptom?
PSP and CBD which are both have tauopathy
What is the most common form of motor neuron disease?
Amyotrophic lateral sclerosis (ALS) which has genetic forms and sporadic forms
