Multiple Sclerosis Flashcards
What is multiple sclerosis?
A chronic autoimmune disease of the central nervous system
There are multiple, disseminated plaques of demyelination within the brain and spinal cord
MS affects Schwann cells.
True or false?
False!
It affects oligodendrocytes
MS only affects the central nervous system, and these neurons are myelinated by oligodendrocytes
Which cells myelinate the CNS and PNS?
CNS: oligodendrocytes
PNS: Schwann cells
Epidemiology of MS?
Disease usually begins in early adulthood: ages 20-40
More common in women
Affects Caucasians more than others
Aetiology of MS? What causes it?
A combination of chance, genetic and environmental factors
Multiple genes are involved in MS
Environmental factors include:
- race
- latitude, vitamin D exposure
- age
- socio-economic status
- exposure to EBV in childhood
Why does exposure to Epstein-Barr virus increase the risk of MS?
Exposure to EBV triggers an immune response
In some people (with a particular genetic make up) the antibodies produced against EBV start to attack the myelin sheath because of molecular mimicry
What is the link between vitamin D exposure and MS?
Sufficient levels of vitamin D can be preventative of MS
It also can result in fewer symptoms and lesions in MS
What features of the immune system are involved in MS?
Lymphocytes
Monocytes
Complement
Cytokines
In terms of the immune system, what is the pathogenesis of MS?
Autoreactive T lymphocytes are triggered by genetic or environmental reasons
They activate B cells, macrophages, complement
These all come together to form a complete inflammatory attack on myelin sheath
After being damaged, does the myelin sheath regenerate?
Yes but not completely
Re-myelination occurs but it forms a thinner layer
Also the distance between each Node of Ranvier is shorter
Still not as efficient as a normal myelin sheath
Conduction is still slower
What does the myelin sheath do?
Speeds up conduction of nerve impulses
The depolarisation jumps between the myelin cells from Node of Ranvier to Node of Ranvier
What sites in the nervous system does MS affect?
Cerebral hemispheres
Optic nerves
Medulla and pons
Optic nerve
How do people usually first present with MS?
Optic neuritis, visual symptoms
Numbness or tingling in the limbs
Muscle weakness, spasticity
Clinical features of MS?
Visual symptoms:
- optic neuritis
- nystagmus, double vision
Spasticity + weakness in limbs
Sensory signs:
- tingling, numbness
- Lhermitte’s sign
Bladder + sexual function
What is optic neuritis?
Clinical features?
Inflammation of optic nerve
Cloudy or complete vision loss
Loss of colour vision, dim vision
Pain when moving eyes
What is Lhermitte’s sign?
A sudden sensation like an electric shock that passes down the back of the neck, into the spine and then radiates out into the arms and legs
What is the essential diagnosis criteria?
2 or more CNS lesions disseminated in space and time
The lesions should give a different clinical picture
A patient presents with optic neuritis. 6 months ago they presented with a similar problem.
Could this count as an MS diagnosis?
No, because the problems were too similar
The problems need to be different
There are 4 types of disease progression in MS. What are they?
Relapsing / remitting
Primary progressive
Secondary progressive
Progressive relapsing
Describe the disease progression of relapsing / remitting MS.
Unpredictable attacks, which may or may not leave permanent deficits after them
Interspersed with periods of remission
What is primary progressive MS?
Steady increase in disability, without attacks
What is secondary progressive MS?
Progression is initially relapsing/remitting
Suddenly though, decline progresses without remission + relapse
What is progressive relapsing MS?
Steady decline interspersed with attacks
Investigations of MS?
Examine their reflexes: they are usually exaggerated in MS
Brain MRI: shows lesions, often around the ventricles
Spinal cord MRI: also shows lesions
Lumbar puncture: oligoclonal bands
