Flashcards in Demyelination and dementia Deck (60)
What is demyelination?
Preferential damage to the myelin sheath
Relative preservation of the axons
What is the function of oligodendrocytes?
Locally confining neuronal depolarisation
Forming nodes of ranvier
What are examples of primary demyelinating disorders?
Acute disseminated encephalomyelitis
Acute haemorrhagic leukoencephalitis
What are examples of secondary demyelinating disorders?
Metabolic: central pontine myelinolysis
Toxic: CO, organic solvents, cyanide
What is MS?
Auto-immune demyelination disorder characterised by distinct episodes of neurological deficits, separated in time and which correspond to spatially separated foci of neurological injury
What is required for the clinical diagnosis of MS?
Two distinct neurological deficits occurring at different times
A neurological deficit implicating one neuro-anatomical site and a MRI appreciated deficit at another neuro-anatomical site
Multiple distinct CNS lesions on MRI
What are tests that can be run in MS to support the diagnosis?
Visual evoked potentials; evidence of slowed conduction
IgG oligoclonal bands in CSF
What are the clinical features of MS?
Spinal cord lesions; motor or sensory deficit in trunk and limbs, spasticity, bladder dysfunction
Brain stem lesion: CN sign, ataxia, nystagmus, INO
Whatare the different types of MS?
Acute or insidious
Relapsing and remitting
What does MS look like morphologically?
White matter disease
Cut surface shows plaques
What are plaques in MS?
Well circumscribed, well demarcated
Irregular shaped areas
Glassy, translucent appearance
Vary from small to large
What are frequently affected locations in MS?
Adjacent to lateral ventricles
Optic nerves and chiasm
Ascending and descending fibre tracts
What will active plaques show?
Perivascular inflammatory cells
What will inactive plaques show?
Little remaining myelinated axons
Oligodendrocytes and axons reduced in number
Where are acute lesions commonly found?
Surrounding white matter
Where are chronic lesions commonly found?
Around lateral ventricles
What are the environmental factors of MS?
Assoc with latitude
Relationship with vit D deficiency
EBV viral trigger
What are the genetic risk factors for MS?
Why is MS classified as an immune mediated disease?
Lymphocytic infiltration in histology
Oligoclonal IgG bands in CSF
Genetic linkage to HLA DRb1
What are degenerative diseases of the cerebral cortex?
What are degenerative diseases of the basal ganglia and brain stem?
Progressive supranuclear palsy
Multiple system atrophy
What are degenerative diseases of the spinocerebellar system?
What are degenerative diseases of the motor neurons?
What is the pathogenesis of degenerative diseases?
Simple neuronal atrophy and subsequent gliosis
What is dementia?
An acquired and persistent generalised disturbance of higher mental functions in an otherwise fully alert person
What are the primary dementias?
What are the secondary dementias?
Infection; HIV, syphilis
What is the commonest dementia?
What genes are implicated in alzheimer's?
Amyloid precursor protein (APP) - chromosome 21
Presenilin 1 - chromosome 14
Presenilin 2 - chromosome 1