Demyelinating disorders Flashcards
Approximately what percentage of the brain consists of grey and white matter?
50% white matter
50% grey matter
In a foetus, when does myelination begin?
In the third trimester with a rapid increase at birth.
Which cells transform into oligodendrocytes?
Oligodendrocyte precursor cells
The larger (thicker) the axon, the ___ wraps of myelin.
More.
Spiral wrapping during myelination is dependent on which transmitters?
Gliotransmitters.
For the formation of myelin in the PNS, proteins on an axon surface interact with glial cell receptors. What is an example of a protein and receptor that does this?
Neuroregulin 1 type 3 protein
Erb b receptor
Prior to a signal moving from one node of ranvier to another, the axon depolarises and what ion channel opens?
Na+.
An action potential is generated following axon depolarisation and the opening of Na+ channels. How does this axon repolarise?
By the opening of K+ channels.
What is demyelination?
Damage and loss of the myelin sheath, leading to the slowing or blocking of nerve messages.
What is leukodystrophy?
A condition where there is a failure to myelinate axons.
Multiple sclerosis is caused by demyelination in which nervous system?
Central.
Which environmental factor is linked to multiple sclerosis?
Lack of sun/vitamin D exposure
Which infection has been linked to multiple sclerosis?
EBV
Which gender is more commonly affected by multiple sclerosis?
Female
Which modifiable risk factors are associated with multiple sclerosis?
Smoking
Obesity
In multiple sclerosis, which cells enter the brain and attack myelin?
Immune T cells
During a remission in multiple sclerosis, what is happening to axons?
They’re being remyelinated.
Does everyone recover from multiple sclerosis?
No - can go onto a secondary progressive phase.
Demyelination in different areas of the CNS will still cause the same symptoms. T/F?
False
What different symptoms are associated with multiple sclerosis?
In multiple sclerosis, what feature is common on imaging?
Presence of short segmental lesions/multiple sclerotic lesions.
Which of the 5 senses is commonly affected at the start of multiple sclerosis?
Vision
Difficulties with balance, coordination + tremor are common in multiple sclerosis. Where do these originate from in the brain?
Cerebellum.
In multiple sclerosis, the spinal cord is commonly affected. What type of symptoms could this cause?
Change in sensation
Loss of strength (weakness, spasticity, brisk reflexes)
Bladder + bowel problems.
In multiple sclerosis, the optic nerve is commonly affected. Which painful eye condition can this lead to?
Optic Neuritis
What are the common symptoms of optic neuritis?
Reduced vision - central/colour
Pain on eye movement
Reduced visual acuity (objects/shapes)
Swollen optic disk
What is Lhermitte’s sign?
Sign of MS.
Put head down + get shooting pains down spine or into arms.
Which scale is used to measure disability?
Expanded Disability Status Scale.
How is an acute episode of MS treated?
With steroids
Guillan-Barre Syndrome is a demyelinating disease in which nervous system?
Peripheral.
What PNS demyelinating condition often follows after a recent infection?
Guillan-Barre Syndrome.
What infections are linked to Guillan-Barre Syndrome?
Campylobacter
URTI
Hep E
COVID
What causes an infection to lead to Guillan-Barre Syndrome?
Antibodies made to fight the infection cross react and instead attack the myelin sheath. This is called molecular mimicry.
What is another name for Guillan-Barre Syndrome?
Acute Demyelinating Polyradiculoneropathy.
Which condition common in Asian countries affect the nerve, rather than the myelin?
AMAN
Acute Motor Axonal Neuropathy.
Which condition common in Asian countries affect the nerve, rather than the myelin?
AMAN
Acute Motor Axonal Neuropathy.
How does Guillan-Barre Syndrome typically progress?
Slowly over 2-4 weeks, reaches a peak at 4-6 weeks then usually recovers.
In Guillan-Barre Syndrome, after recovery when are symptoms likely to present again?
Almost never - it’s a monophonic illness.
Only in a small minority of people do symptoms reoccur.
How is Guillan-Barre Syndrome treated?
Supportive management
IV immunoglobulin
Plasma exchange
