Multiple Sclerosis Flashcards
(39 cards)
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
How soon do symptoms appear in MS?
Symptoms usually progress over more than 24 hours. At the first presentation, symptoms tend to last days to weeks and then improve.
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
Briefly describe the managment and prognosis of a patient presenting with optic neuritis
Patients presenting with acute loss of vision should be seen urgently by an ophthalmologist for assessment.
It is treated with steroids and recovery takes 2-6 weeks.
Around 50% of patients with a single episode of optic neuritis will go on to develop MS over the next 15 years. Changes on an MRI scan help to predict which patients will go on to develop MS.
MS is the most common cause of optic neuritis. What else can cause optic neuritis?
- Sarcoidosis
- Systemic lupus erythematosus
- Diabetes
- Syphilis
- Measles
- Mumps
- Lyme disease
How does optic neuritis present on fundoscopy?
In acute optic neuritis, the fundus appears normal because two thirds of cases of optic neuritis are retrobulbar. With time, the optic nerve may become pale. One third of patients with optic neuritis have a swollen disc (papillitis). The disc edema of optic neuritis often is diffuse
What eye abnormalities are associated with MS?
Patients may present with double vision due to lesions with the sixth cranial nerve (abducens nerve).
There are two key phrases to remember to describe a sixth cranial nerve palsy:
- Internuclear ophthalmoplegia
- Conjugate lateral gaze disorder
Briefly describe internuclear ophthalmoplegia
Unilateral lesions in the sixth nerve causes a condition called internuclear ophthalmoplegia. Internuclear refers to the nerve fibres that connect between the cranial nerve nuclei that control eye movements (3rd, 4th and 6th cranial nerve nuclei). The internuclear nerve fibres are responsible for coordinating the eye movements to ensure the eyes move together. Ophthalmoplegia means a problem with the muscles around the eye.
Briefly describe conjugate lateral gaze disorder
Lesions in the sixth cranial nerve cause a conjugate lateral gaze disorder. Conjugate means connected. Lateral gaze is where both eyes move together to look laterally to the left or right. It is disordered in a sixth cranial nerve palsy. When looking laterally in the direction of the affected eye, the affected eye will not be able to abduct.
For example, in a lesion affecting the left eye, when looking to the left, the right eye will adduct (move towards the nose) and the left eye will remain in the middle as the muscle responsible for making it move laterally is not functioning.
