Intro to Neuropathology Flashcards
What two things are considered glia?
Astrocytes
Oligodendrocytes
What is selective vulerability?
Neurons don’t necessarily have to be located together so response to insult have many consequences.
- Ex) Neurons can be located in temporal lobe and cerebellum, etc
What happens in the acute neuronal response to injury? (12-24h)
What significant does this have as an indicator?
Red neurons
-Earliest morphologic indicator of acute insult
What are red neurons and how do they come to be? (4)
- Shrinkage of cell body
- Pyknosis
- Loss of nucleolus
- Loss of Nissl substance with intense eosinophilia of cytoplasm
What happens in subacute or chronic neuronal injury (degeneration or progressive disease)?
What significant does this have as an indicator?
- Cell loss & reactive gliosis; apoptosis
- Best indicator of neuronal injury
What is gliosis?
What significant does this have as an indicator?
Essentially “scar tissue” of the brain
- Most important histopathologic indicator of CNS injury, regardless of etiology (pharm, trauma, etc)
- Hypertrophy and hyperplasia of astrocytes
What is an axonal reaction in neuronal injury? What happens?
Inc in protein synthesis a/w axonal sprouting
- Enlarged/rounded cell body
- Periph displacement of nucleus
- Enlarged nucleolus (b/c it’s very active)
- Nissl removed from center of cell to periphery (central chromatolysis)
Side note: Chromatolysis and lipofuscin are normal processes
What are neuronal inclusions in relation to neuronal injury? (2)
- Intracytoplasmic
- Intranuclear
What is an intracytoplasmic inclusion? Rabies Alzheimers Parkinsons CJD
Lipofuscin, proteins, or carbohydrate accumulations
- Rabies: Negri bodies
- Alz: Neurofibrillary tangles
- Parkinson: Lewy bodies
- CJD: Vacuolization of perikaryon & neuronal processes
What is an intranuclear inclusion?
Herpes
CMV
- Herpes: Cowdry body
- CMV: Both intranuclear and cytoplasmic; Owl’s eye inclusions
What are three things that can happen with astrogliosis?
Gliosis, calcifications forming, keratin forming
- Side note: Any tumor that would “spill” contents into or adjacent to brain parenchyma would produce a localized injury and astrogliosis
What are rosenthal fibers?
What are corpora amylacea?
Rosenthal fibers: Thick, elongated, brightly eosinophilic irregular structures occurring w/i astrocytic processes
- Areas of longstanding gliosis; pilocytic astrocytoma
- If we see Rosenthal fibers this is likely a good sign of a slow growing, benign tumor
Corpora amylacea: Round, faintly basophilic, concentrically laminated strictures located adjacent to astrocytic end processes
- PAS +
- Inc with age, represent degenerative change
What are microglia and what are their surface markers?
Macrophages of the CNS
- Surface markers CR3 and CD68 (same as periph macrophages)
- Aggregate around a small foci of necrosis and around cell bodies of dying neurons)
Cerebral edema:
What is vasogenic edema? When and why do we see this?
Inc in extracellular fluid d/t BBB disruption and inc vascular permeability; often follows ischemic injury
- Hard to shift xs fluid out of brain bc no lymphatics
Cerebral edema:
What is cytotoxic edema?
Inc in intracellular fluid secondary to neuronal, glial, or endothelial cell membrane injury
What can a choroid plexus papilloma lead to?
Inc in CSF (d/t xs choroid plexus) leading to hydrocephalus (looks like broccoli)
Pyogenic meningitis:
Where is a typical spot to see exudate in TB or syphilis?
What happens to the meninges and what can this cause?
Base of the brain. Thickened leptomeninges can lead to obstructive hydrocephalus
Name 6 causes of congenital hydrocephalus
- Intrauterine (TORCH) infections
- Agenesis/atresia/stenosis
- AV malformation
- Arnold-Chiari malformations
- Dandy-Walker syndrome
- Cranial defects like achondroplasia or craniostenosis (sutures ossify prematurely)
Name 8 causes of acquired hydrocephalus
- Infections (meningitis, meningoencephalitis, cysticercosis)
- Mass lesions (neoplasms like medulloblastoma, astrocytoma)
- Inflammation (brain abscess)
- Post hemorrhage (IVH, SAH, Injury)
- Choroid plexus papilloma/carcinoma
- Sagittal sinus thrombosis
- Hypervitaminosis A (softening of skull bones in infants and kids)
- Idiopathic
Features of communicating hydrocephalus
- CSF is not properly absorbed at level of dural sinus
- Ventricles are symmetrically dilated
- No single point of obstruction
What is Hydrocephalus Ex-Vacuo? What are some features?
- Shrinkage of brain substance (Atrophy w inc age, stroke or other injury, neurodegenerative process)
- Dilation of ventricles
- CSF Pressure is normal
What is normal pressure hydrocephalus? What are some features?
- Symmetric hydrocephalus
- Occurs in adults, typically over 60yo
- Drainage of CSF is gradually blocked but ventricular system enlarges too so pressure don’t elevate too much
- Can be reversible
- “wet, wacky, wobbly” = incontinence, dementia, magnetic and broad-based gait
What are 3 things that increased ICP are generally due to?
- Generalized brain edema
- Expanding mass lesion (tumor, hemorrhage, abscess, etc)
- Inc CSF volume
What is herniation?
Inc pressure beyond the compensatory ability of the venous system to compress & displace CSF. Tissue herniates past the rigid dural holds (flax & tentorium) or through skull openings
What are 3 types of herniation?
- Subfalcine (cingulate): Cingulate gyrus displaced under the falx
- Transtentorial (Uncinated, Uncal, etc): Medial aspect of the temporal lobe is compressed against tentorium; CNIII compression leads to dilated pupil & impaired eye movement
- Tonsillar: Cerebellar tonsils displaces thru the foramen magnus; this is life threatening d/t compression of the respiratory & cardiac centers