Neuropathology 3: Dementia and Demyelinating Disorders Flashcards
how do oligodendrocytes facilitate saltatory conduction?
by forming nodes of ranvier
demyelination causes defects in the __ and ___ of neuroconduction
rate
consistency
axons are preserved in demyelinating disorders T or F
T
multiple sclerosis is a primary cause of demyelination T or F
T
name secondary causes of demyelination
viral eg leukoencephalopathy
metabolic eg central pontine myelinosis
toxic eg CO, solvents
primary causes of demyelination
MS
acute disseminated encephalomyelitis (ADEM)
acute haemorrhagic leukoencephalomyelitis
patient with hyponatraemia that is overly corrected can cause…
central pontine myelinosis
lesions in MS occur in the __ matter; why?
white
this is the area of the brain with myelinated axons
what is found in CSF in an MS patient?
IgG oligoclonal bands
visual impairment is __lateral in optic neuritis?
uni
MS is primarily a disease of the __ matter
white
the lesions are mainly on the outside of the brain in MS T or F
F, in middle
what do the lesions in MS look like?
glassy, thin
non symmetrical
where are MS plaques found?
periventricular white matter corpus callosum optic nerves and chiasm brainstem spinal cord
active plaques show evidence of…
inflammatory cells
microglia
active demyelination
what do demyelinating plaques look like?
yellow/brown with an ill defined edge that blends into the surrounding white matter
chronic plaques show evidence of..
gliosis
loss of myelin
less oligodendrocytes and axons
what do inactive plaques look like?
well demarcated grey brown lesions located around the lateral ventricles
does MS have a genetic component?
yes, 15x risk if 1st degree relative
MS has genetic linkage to what gene complex?
HLA DR2
what degenerative diseases affect the cerebral cortex?
alzheimers
CJD
pick disease
main pathological process in degenerative disease?
simple neuronal atophy
subsequent gliosis
what degenerative diseases affect the brainstem and basal ganglia
parkinsons
huntingtons
define dementia
acquired and persistence generalised disturbance of higher mental functions in an otherwise fully alert person
dementia is part of the normal ageing process T or F
F, always pathological
dementias tend to present symmetrically T or F
T
name primary dementias
alzheimers
lewy body
vascular
frontotemporal
alzheimers tends to present after age __
60
is alzheimers familial?
not really, only about 1%
what gene is said to be implicated in alzheimes?
amyloid precursor protein
how does alzheimers progress?
onset is subtle but once symptoms begin the patient deteriorates quickly with disorientation and memory loss
what happens to the appearance of the brain in alzheimers?
cortical atrophy
widening of sulci and narrowing of gyri
frontal, temporal and parietal lobe atrophy
what parts of the brain are NOT affected in alzheimers?
brainstem
cerebellum
classic microscopic appearance of alzheimers
neuronal loss -> gliosis
neurofibrillary tangles (aggregates of tau protein) are characteristic
amyloid plaques
what genetic condition is associated with early onset of alzheimers?
down syndrome
name the protein responsible for creating neurofibrillary tangles
tau protein
main component of amyloid plaques? how do they kill neurons
amyloid beta
promote excitotoxicity
what amyloid disease are alzheimers patients at risk of?
amyloid angiopathy (disrupts BBB)
describe lewy body dementia; how is it different from alzheimers?
progressive dementia WITH: hallucinations fluctuating attention and cognition REM sleep disorder (acting out dreams) parkinsonism
NB memory loss occurs much later
why do you get parkinsonism in lewy body dementia?
lewy body affects the nigro striatal dopaminergic pathways
main pathological process in lewy body dementia
degeneration of the substantia nigra due to gliosis of dopaminergic neurons
microscopic appearance of lewy body dementia
lewy bodies (discrete eosinophilic lesions surrounded by a pale halo)
reactive gliosis
loss of pigmented neurons
main age of onset in huntingtons?
35-50
name the triad of symptoms in huntingtons?
triad of emotional, cognitive and motor disturbance
symptoms in huntingtons?
chorea myoclonus clumsiness slurred speech depression irritability dementia develops MUCH LATER
what chromosome carries the huntington gene?
4
dementia is an early feature of huntingtons T or F
F, occurs much later
main pathological process in huntingtons - be specific
atrophy of the caudate nucleus in the basal ganglia
frontal and parietal atrophy
microscopic appearance of huntingtons
degenerations of striatal neurons in the caudate nucleus
gliosis
frontotemporal dementia is also called…
picks disease
what dementia is known to begin early (in middle life)
fronto-temporal
fronto-temporal dementia macroscopic appearance?
extreme atrophy of cerebral cortex starting in frontal and later affecting the temporal lobesp
what are picks cells? what do they present in?
swollen neurons
fronto-temporal dementia
cerebrovascular dementia occurs due to what pathological process
hypoxia or anoxia
you need to lose ___mls of brain before the dementia begins in CV dementia
50-100
how does CV dementia differ from alzheimers?
abrupt onset rather than insidious
stepwise progression rather than smoothly progressive
history of CV problems eg HT/stroke
classic macroscopic appearance of CV dementia
large vessel infarcts scattered through hemispheres with atheroma of large cerebral arteries
