PNS, neuropath, neurocytology Flashcards
segmental demyelination
- happens in schwann cells
- could be dysfunction (m. or sensory neuropathy) or acquired damage (Guillain-Barre)
- axon intact; purely problem w/ myelination
- peripheral n. will try to remyelinate; onion bulbs in CS
grouped atrophy
- happens when m. fibers lose their innervation
- atrophic fibers look small and angular
- seen in ALS, traumatic injury
Wallerian degeneration
- happens to the distal portion of a transected n.
- axon begins to break down; schwann cells start to destroy myelin and engulf the axon fragments
- macrophages to the area
what happens to the proximal portion of a transected n.?
- degeneration for 2-3 distal internodes
- undergoes regenerative activity
Guillain-Barre syndrome
- active inflammatory demyelinating polyradiculoneuropathy
- ascending paralysis; areflexia
- can be caused by vaccinations
Charcot-Marie-Tooth
- autosomal dominant demyelinating disease
- kids or young adults
- ascending demyelination but generally only below the knee
- pes cavus = key finding; atrophy will set in; progressive paralysis
Lambert-Eaton syndrome
- ds of NMJ; can be presentation of small cell lung carcinoma
- proximal m. weakness
- inc. NCS w/ repetitive stimulation
mature neurons do not …?
- DIVIDE!
- loss of neurons w/ age
- CNS neurons don’t regenerate over long distances
- infarcts that transect internal capsule = permanent motor deficits
neuromelanin
- located in substantia nigra
- locus coeruleus
- CNVI
- median raphe
- highly eosionophilic granular appearance
chromatolysis
- damage to neuron
- injured neuron swells = nissl substances to periphery = nucleus becomes eccentric
histo characteristics of prion disease
- seen in creutzfeld-jacob disease
- spongiform encephalitis = holes make it look like a sponge
- neurons very atrophied; become hyperchromatic
histo changes in CMV
- would see clear ‘halos “ around nuclei
histo changes in rabies
- cytoplasmic “Negri body”
- looks like RBC
astrocytes
- star shaped glial cells
- stain w/ GFAP or silver = will look eosinophilic
- found in gray and white matter; act as BBB
most important histo indicator of CNS injury?
- astrocytosis aka reactive gliosis
- 12h - 2d after injury; result in glial scar
oligodendrocytes
- make myelin for axons
ependymal cells
- line ventricular system
- regulate CSF transport
microglia
- fixed macrophages
- proliferate w/ injury
- will surround a dying neuron; basically the clean up crew of CNS
red neuron
- result of acute CNS hypoxia/ischemia in first 24h after injury ex: drowning case autopsy
- just looks like red dots on H&E stain
what type of cell and what area of the brain are most sensitive to hypoxia/anoxia?
- cell = neuron
- part of brain = hippocampus
gemistocytic astrocytes signal what?
- brain injury
- astrocytes swell and cytoplasm becomes bright pink
