Pathology - Demyelination and Dementia Flashcards
what is demyelination?
preferential damage to the myelin sheath
name three causes of primary demyelination
MS
acute disseminated encephalomyelitis (ADEM)
acute haemorrhagic leukoencephalitis (AHL)
name three potential causes of secondary demyelination
viral illness
metabolic issues
toxins
what is the most common demyelinating disease?
multiple sclerosis (MS)
which sex is more commonly affected by MS?
females
when does incidence of MS peak?
20-30 year olds
what is MS?
an autoimmune demyelinating disorder characterised by distinct episodes of neurological deficit, separated in time
how is MS diagnosed?
clinical diagnosis when there are two distinct neurological deficits occurring at different times
or
deficit implying one affected site and an MRI defect at another site
what imaging can be done for MS and what is seen?
MRI
multiple distinct lesions, white on T2 weighted MRI
what other investigations can be done to support a diagnosis of MS?
visual evoked potentials showing slowed conduction
IgG oligoclonal bands in CSF
name the four forms of MS
clinically isolated
relapsing and remitting
primary progressive
secondary progressive
describe the morphological appearance of the brain in MS
outside appears normal
cut surface shows plaques
describe the appearance of the plaques formed in MS
well circumscribed, irregular shaped
translucent appearance
very in size
name some areas frequently affected by plaques in MS
adjacent to lateral ventricles corpus callosum optic nerves brainstem cerebellum spinal cord
name some degenerative diseases that affect the cerebral cortex
alzheimer’s
pick disease
CJD
name some degenerative diseases that affect the basal ganglia and brainstem
parkinson’s
progressive supranuclear palsy
multiple system atrophy
huntington’s
what is dementia?
an acquired and persistent generalised disturbance of higher mental functions in an otherwise fully alert person
name four types of primary dementia
huntington’s
pick’s disease
lewy body dementia
alzheimer’s
what is the most common cause of dementia in the elderly?
alzheimer’s
is alzheimer’s more common in males or females
twice as common in females
name some implicated genes in familial alzheimer’s
amyloid precursor protein (APP)
presenilin 1+2
how does alzheimer’s present?
insidious impairment of higher intellectual function with alterations in mood and behaviour
what often causes death in patients with alzheimer’s?
secondary causes like bronchopneumonia
what macroscopic changes are seen in alzheimer’s?
cortical atrophy
wide sulci + narrow gyri
dilatation of ventricles
where in the brain is affected by cortical atrophy in alzheimer’s?
frontal, temporal and parietal lobes
what microscopic changes are seen in alzheimer’s?
neuronal loss
neurofibrillary tangles
neuritic plaques
amyloid angiopathy
how does lewy body dementia present?
progressive dementia
hallucinations
fluctuating attention + cognition
parkinsonism
what is the pathology behind lewy body dementia?
degeneration of the substantia nigra
what macroscopic changes are seen in lewy body dementia?
pallor in the substantia nigra
what microscopic changes are seen in lewy body dementia?
loss of pigmented neurons
reactive gliosis
lewy bodies - spread from brainstem to cortex
what is another name for pick’s disease?
fronto temporal dementia
how does pick’s disease present?
progressive dementia commencing in middle life characterised by changes in character and social deterioration leading to impairment of intellect, memory and language
what macroscopic changes occur in pick’s disease?
extreme atrophy of the cerebral cortex in frontal and temporal lobes
brain weight <1kg
what can be seen on histology in pick’s disease?
neuronal loss
gliosis
pick’s cells
pick’s bodies
what are pick’s cells?
swollen neurones
what are pick’s bodies?
intracytoplasmic filamentous inclusions
when does huntington’s tend to come on?
35-50
can occur at any time though
what is the triad of clinical features of huntington’s?
emotional, cognitive and motor disturbances
how is huntington’s inherited?
autosomal dominant pattern
mutation in the huntingtin gene on chromosome 4 - increased number of CAG repeats
what macroscopic changes are seen in huntington’s?
atrophy of the basal ganglia, caudate nucleus and putamen
later on can have frontal, parietal and cortical atrophy
what is a secondary dementia?
when another disorder gives rise to dementia
e.g, vascular dementia due to multiple infarcts
