MULTIPLE SCLEROSIS Flashcards
What is multiple sclerosis?
An acquired, chronic, immune-mediated inflammatory condition of the central nervous system. It can affect the brain, brainstem and spinal cord
What are glial cells?
A type of cell that provides physical and chemical support to neurons and maintain their environment
What is an astrocyte?
A type of glial cell that has many roles in supporting the neurones
What are oligodendrocytes and what are their major function?
These are a type of glial cell
Wraps myelin around the neuron to allow for a more rapid transmission of the impulse
Pathophysiology of multiple sclerosis?
Thought to be inflammation precipitated by an abnormal response to environmental triggers in people who are genetically predisposed.
T cells attack oligodendrocytes which can cause focal or diffiuse areas of inflammation which causes areas of demyelination (plaques), gliosis (scarring) and neuronal damage throughout the CNS
Progressive damage to affected cells in the nervous system leads to irreversible loss of function of affected nerves, resulting in permenant sytmptoms and signs
Do neurones fully repair during remission of MS?
No
Remyelination of axons may occur but it will be partial or transient
Axons themselves cannot repair
What are the 3 main patterns of MS?
Relapsing-remitting 85%
Secondary progressive - 2/3rds of those with relapsing remitting disease progress to this
Primary progressive 10-15%
What is relapsing-remitting MS?
Episodes or exacerbations of symptoms followed by remissions or periods of stability
Can be weeks to decades between episodes! Duration can be days-months
Recovery period can be complete or incomplete
What is secondary progressive MS?
Initially relapsing-remitting usually. Later progression with gradual ongoing deterioration. Relapses can still occur by they are less likely!
50% by 10 years but this is very variable
What is primary progressive MS?
Steady progression and worsening of disease from onset, without remissions
The rate of deterioration may vary
Usually more spinal cord involvement
What are plaques in MS?
These are areas of demyelination that are found in the white matter of the CNS
They usually lie in close relationship to post-capillary venules
Risk factors for MS?
Genetics
Vitamin D deficiency
Cigarette smoking
Diet and obesity in early life - possible due to lower vit D levels
Latitude - the greater the distance N or S from the equator - lack of vit D?
EBV
Female gender
Epidemiology of MS?
Onset usually 20-50
Affects women: men up to 3:1
Most common initial presentations of MS?
Optic neuritis
Transverse myelitis
Cerebellar-related symptoms
Brainstem syndromes
Symptoms of MS?
Can be very mild or very severe and symptoms depend on where in the brain is affected
Visual:
- optic neuritis
- optic atrophy
- uhthoffs phenomenon
- inter nuclear ophthalmoplegia
Sensory:
- pins & needles
- numbness
- trigeminal neuralgia
- lhermitte’s syndrome
Motor:
- spastic weakness most commonly legs
Cerebellar:
- ataxia
- tremor
Others:
- 75% have fatigue
- Urinary incontinence
- sexual dysfunction
- intellectual deterioration
How does optic neuritis present?
Partial or total unilateral visual loss developing over a few days - e.g. scotoma
Pain behind eye on eye movement
Loss of colour discrimination - esp red
On exam:
Relative afferent pupillary defect
Papilloedema in 30%
Scotoma in 70%
What is transverse myelitis and how does it present?
Focal inflammation within the spinal cord
May present with sensory or motor symptoms below the level of inflammation e.,g. Numbness, weakness.
Some people describe a tight band sensation around the trunk or lhermitte’s phenomena.
There may be urinary symptoms
What is Lhermitte’s syndrome?
Paraesthesia in the limbs on neck flexion
What is Uhthoff’s phenomenon?
Worsening of vision following a rise in body temperature
When can a diagnosis of MS be made?
When there are 2 or more relapses + either objective clinical evidence of 2 or more lesions, OR objective clinical evidence of 1 lesions with reasonable historical evidence of a previous relapse
MRI findings in MS?
Soft, fluffy, ovoid areas of high signal on T2 - peri ventricular plaques
common sites include peri ventricular, corpus callosum, posterior fossa and sub-cortical
Dawson fingers - hyperintense lesions perpendicular to the corpus callosum
What is a pseudo-relapse of MS?
A temporary worsening of existing or old symptms due to decompensation
E.g. infection, stress, tiredness, weather changes
Important to differentiate this between relapses
Diagnosing a relapse of MS?
New symptoms of existing symptoms have worsened and they have lasted for >24 hours in the absence of infection or any other cause.
Must occur after a stable period of at least 1 month
Investigtaions for MS?
MRI brain & spinal cord
Lumbar puncture for CSF - usually only done if clinical/investigative evidence is lacking
Electrophysiology - Visual evoked potentials - light patterns are shown to eyes whilst brainwaves are monitored using electrodes - shows delayed VEP indicating optic neuropathy in 85%
