Demyelinating disorders Flashcards
Nodes of ranvier precipitate what type of conduction?
Saltatory conduction
Schwann Cells have a limited capacity to remyelinate after damage TRUE/FALSE
FALSE
Oligodendrocytes have a limited capacity to demyelinate after damage
Many neurological disorders cause damage to the myelin. Therefore what classifies a demyelinating disorder?
Demyelinating disorder is where there is preferential damage to the myelin
Name 3 primary demyelinating disorders
Multiple sclerosis
Acute disseminated encephalitis (ADEM)
Acute haemorrhage leukoencephalitis (AHL)
Acute disseminated encephalitis is rapidly fatal TRUE/FALSE
FALSE
Acute disseminated encephalitis is mild, self-limiting and low mortality (mainly in children)
What is multiple sclerosis?
Autoimmune demyelinating disorder characterised by distinct episodes of neurological deficits, separated in time and which correspond to spatially separated foci of neurological injury
What is the most common phenotype of multiple sclerosis?
Relapsing and remitting
Risk factors for MS?
Higher latitudes Previous EBV exposure (viral trigger) 1st degree MS relative HLA DRB1 Young females
What is the prevalence of MS?
1/1000
What is the pathophysiology of the plaques in MS?
T cells cause inflammation and damage to oligodendrocytes in CNS which leaves behind scarred areas of demyelinated neurones called plaques
What do plaques look like?
Well circumscribed and demarcated
Glassy translucent quality
vary from small to large lesions
What are common areas of demyelination?
Corpus callous, optic nerve and spinal cord
What are the two types of plaques?
Active
Inactive
As active plaques age, astrocytes undergo reactive change and inflammatory cells reduce in number. Inflammation dampens down and ——- occurs
Gliosis
In inactive cells what predominates?
Gliosis
Macroscopically what is the difference between active and inactive plaques?
Active- yellow/brown with an ill defined edge which blends into surrounding white matter
Inactive- Well-demarcated grey/brown lesions in white matter, classically situated around lateral ventricles
What are shadow plaques?
Inactive plaques that appear less distinct and less well circumscribed due to a degree of peripheral demyelination or progressively thinned out myelin sheaths
TRUE/FALSE symptoms of MS can worsen with fever or high temperatures
TRUE dat
What is presentation of MS typically?
Focal neurological deficit –> often resolves in early disease
Followed by emergence of another different deficit which worsens over weeks and linger for months
What is pathognomic of MS?
Bilateral INO (Internuclear opthalmoplegia)
What is Lhermitte’s sign?
Electric shock like sensations down the upper limbs and trunk on neck flexion
What in Uhthoff’s phenomenon?
Exacerbation of current symptoms in hot environment i.e. after a hot shower
What are the categories that the symptoms of MS fall into?
Pyramidal dysfunction
Ocular symptoms
Sensory symptoms
Cerebellar dysfunction
What does DANISH stand for?
DANISH is the acronym for the cerebellar symptoms of MS D- Dysdiadochokinesia A-Ataxia N-Nystagmus I-Intention tremor (and past pointing) S- Slurred speech H- Hypotonia
