Multiple Sclerosis Flashcards
What is multiple sclerosis (MS)?
Multiple sclerosis (MS) is defined as an inflammatory demyelinating disease characterised by the presence of episodic neurological dysfunction in at least two areas of the central nervous system (brain, spinal cord, and optic nerves) separated in time and space.
Who is the typical MS patient?
MS typically presents in young adults (under 50 years) and is more common in women.
How does pregnancy and the postpartum period affect MS?
Symptoms tend to improve in pregnancy and in the postpartum period.
At what age do most patients develop MS?
Most commonly diagnosed in people aged 20-40 years.
What are the different disease patterns of MS?
- Clinically Isolated Syndrome
- Relapsing-Remitting
- Secondary progressive
- Primary progressive
Briefly describe ‘Clinically Isolated Syndrome’
This describes the first episode of demyelination and neurological signs and symptoms. MS cannot be diagnosed on one episode as the lesions have not been “disseminated in time and space”. Patients with clinically isolated syndrome may never have another episode or develop MS. If lesions are seen on MRI scan then they are more likely to progress to MS.
Briefly describe the ‘Relapsing-Remitting’ type of MS
Relapsing-remitting MS is the most common pattern at initial diagnosis. It is characterised by episodes of disease and neurological symptoms followed by recovery. In MS the symptoms occur in different areas with different episodes. This can be further classified based on whether the disease is active and/or worsening:
- Active: new symptoms are developing or new lesions are appearing on MRI
- Not active: no new symptoms or MRI lesions are developing
- Worsening: there is an overall worsening of disability over time
- Not worsening: there is no worsening of disability over time
Briefly describe the ‘Secondary Progressive’ type of MS
Secondary progressive MS is where there was relapsing-remitting disease at first, but now there is a progressive worsening of symptoms with incomplete remissions. Symptoms become more and more permanent. Secondary progressive MS can be further classified based on whether the disease is active and/or progressing.
- Active: new symptoms are developing or new lesions are appearing on MRI
- Not active: no new symptoms or MRI lesions are developing
- Progressing: there is an overall worsening of disease over time (regardless of relapses)
- Not progressing: there is no worsening of disease over time
Briefly describe the ‘Primary Progressive” type of MS
Primary progressive MS is where there is a worsening of disease and neurological symptoms from the point of diagnosis without initial relapses and remissions. This can be further classified in a similar way to secondary progressive based on whether it is active and/or progressing.
Briefly describe the physiological structure of nerves and myelin
Myelin covers the axons of neurones in the central nervous system. This myelin helps the electrical impulse move faster along the axon. Myelin is provided by cells that wrap themselves around the axons. These are Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system.
Briefly describe the pathophysiology of MS
Multiple sclerosis typically only affects the central nervous system (the oligodendrocytes). There is inflammation around myelin and infiltration of immune cells that cause damage to the myelin. This affects the way electrical signals travel along the nerve leading to the symptoms of multiple sclerosis.
When a patient presents with symptoms of a clinical “attack” of MS, for example, an episode of optic neuritis, there are usually other lesions of demyelination at the same time throughout the central nervous system, most of which are not causing symptoms.
In early disease, re-myelination can occur and symptoms can resolve. In the later stages of the disease, re-myelination is incomplete and symptoms gradually become more permanent.
A characteristic feature of MS is that lesions vary in their location over time, meaning that different nerves are affected and symptoms change over time. The key expression to remember to describe the way MS lesions change location over time is that they are “disseminated in time and space”.
Which immune cells destroy myelin in MS?
CD4-mediated destruction of oligodendroglial cells and a humoral response to myelin binding protein are important pathological features.
What causes MS?
The cause of the demyelination is unclear, but there is growing evidence that it is influenced by a combination of:
- Multiple genes
- Epstein–Barr virus (EBV)
- Low vitamin D
- Smoking
- Obesity
What are the risk factors of MS?
- Female sex
- Family history of MS
- Northern latitude
- Genetic factors
- Smoking
What are the clinical features of MS?
- Visual disturbance in 1 eye
- Peculiar sensory phenomena
- Foot dragging or slapping
- Leg cramping
- Fatigue
- Urinary frequency
- Bowel dysfunction
What is the most common presentation of MS?
Optic neuritis.
How does optic neuritis present?
Optic neuritis presents with unilateral reduced vision developing over hours to days.
It involves demyelination of the optic nerve and loss of vision in one eye.
Key features are:
- Central scotoma
- This is an enlarged blind spot
- Pain on eye movement
- Impaired colour vision
- Relative afferent pupillary defect
