Flashcards in Chapter 28: The CNS Deck (144)
Neuronal response to injury within 12-24 hours
Show shrinkage of cell body, pyknosis, loss of nucleolus, loss of nissl substance, with intense eosinophilia of cytoplasm
Axonal reaction to injury in which nissl substance is removed from the center of the cell to the periphery
Other axonal reactions to injury include enlarged/rounded cell body, peripheral displacement of nucleus, and enlarged nucleolus
Primary example of neuron intracytoplasmic inclusion
What clinical conditions are neuronal intracytoplasmic inclusions seen in?
Rabies negri bodies, alzheimer nuerofibrillary tangles, parkinson lewy bodies, CJD
Clinical examples of neuronal intranuclear inclusions
Herpes cowdry bodies
CMV has both intranuclear and cytoplasmic inclusions
Most important histopathologic indicator of CNS injury, regardless of etiology
Characterized by hypertrophy and hyperplasia of astrocytes (now called gemistocytes
In what conditions might you see an alzheimer type 2 astrocyte?
Hyperammonemia (chronic liver disease)
Hereditary metabolic disorder of urea cycle
[characteristics include enlarged nucleus, pale staining central chromatin, intranuclear glycogen droplet, prominent membrane and nucleolus]
Thick, elongated, brightly eosinophilic, irregular structures occurring within astrocytic processes and containing 2 heat shock proteins: alpha-B-crystallin and HSP27 as well as ubiquitin
Polyglucosan bodies that are PAS+ associated with increasing age and representative of degenerative change
Surface markers of microglia
CR3, CD68 [same as peripheral macrophages]
One way in which microglia respond to injury is neuronophagia - what is this process?
Microglia congregate around cell bodies of dying neurons
Other glial responses to injury include ________ in PML, which develop intranuclear inclusions
These cells develop glial cytoplasmic inclusions in multiple sytem atrophy (MSA) that contain _________, the product also seen in Parkinsons Lewy bodies
Response of ciliated ependymal cells (line the ventricles) to injury
Disruption of ependymal lining and proliferation of subependymal astrocytes —> ependymal granulations
[seen in CMV]
Difference between vasogenic and cytotoxic cerebral edema
Increased extracellular fluid due to BBB disruption and increased vascular permeability; OFTEN FOLLOWS ISCHEMIC INJURY
Increased intracellular fluid secondary to neuronal, glial, or endothelial cell membrane injury; characteristic appearance of flattened gyri, narrowed sulci, compressed ventricles, and potential complication of HERNIATION
Responses of the body to increased CSF
Absorption by transventricular and nerve root sleeves
Dilation of frontal and temporal horns
Thinning of cerebral mantle
Stretching/perforation of septum pellucidum
Enlargement of 3rd ventricle downwards
***Increased ICP noted as papilledema***
In what condition might hydrocephalus be due to increased production of CSF?
Choroid plexus papilloma
What is communicating hydrocephalus?
CSF is not absorbed properly at the dural sinus level, thus the ventricles tend to be symmetrically dilated
What is hydrocephalus ex vacuo? How is this distinguished from other cases of hydrocephalus?
Dilation of ventricles to compensate for shrinkage of brain substance due to other cause (atrophy with age, stroke or other injury, chronic neurodegenerative disease)
CSF pressure is normal in these cases
Classic triad of symptoms seen with normal pressure hydrocephalus
“Wet, wobbly, wacky”
Urinary incontinence, gait disturbance (magnetic), dementia
3 principle causes of increased ICP
Generalized brain edema
Expanding mass lesion (tumor, abscess, hemorrhage)
Increased CSF volume
What are the 3 types of herniation
Subfalcine (cingulate): cingulate gyrus displaced under falx
Transtentorial (uncal): medial aspect of temporal lobe compressed against the tentorium
Tonsillar: cerebllar tonsils displaced through foramen magnum; life threatening due to respiratory and cardiac center compression
Which type of herniation involves risk to CN3? What are the effects when CN3 is involved?
Transtentorial (uncal) herniation — dilated pupil and impaired eye movement
What is kernohan’s notch phenomenon
Result of compression of cerebellar peduncle against the tentorium cerebelli due to transtentorial herniation
Causes ipsilateral hemiparesis or hemiplegia
[if you have a right hemisphere transtentorial herniation, you have a kernohan’s notch phenomenon in left cerebellar peduncle, which results in right-sided motor impairment]
______ = type of hemorrhage in midbrain and pons associated with progression of transtentorial herniation
And infarct in the CNS results in what type of necrosis?
What general pathology accounts for most CNS malformations?
Neural tube defects [usually folate deficiency]
Diverticulum of disorganized brain tissue extending through defect in cranium; usually posterior fossa
Conditions associated with microcephaly
Fetal alcohol syndrome
What forebrain anomaly is associated with entrapment of meningeal tissue?
Neuronal heterotopias are collections of neurons in innappropriate places (i.e., ventricular surface)along the path of migration; commonly associated with what condition?