9. Multiple Sclerosis Flashcards
What is multiple sclerosis?
Demyelinating disease of the CNS due to lesions in the spinal cord, inflammation and the destruction of myelin sheaths - believed to be immune mediated
This is a chronic disease
What is the cause of MS?
What is the impact on the oligodendrocytes in MS?
What is the role of T cells in MS?
The exact cause is unknown - due to neuronal axonal damage but unsure if this damage is due to an immune response or due to inflammation
Also unsure if the inflammation results from an immune response or if the immune response results from inflammation
May be due to oligodendrocyte damage and stress
MS essentially involves the loss of oligodendrocytes leading to a reduced production of the myelin sheath
Process of ‘remyelination’ occurs in an attempt to repair the myelin sheath around the axons but the oligodendrocytes are unable to fully rebuild it and eventually remyelination is ineffective and ceases to occur
There are also disruptions to the BBB allowing T cells to enter the CNS and they attack it and result in further damage - known as autoreactive lymphocytes
This results in inflammation and the release of cytokines and antibodies and the activation of macrophages
The activated macrophages then lave blood vessels and attack the myelin protein - leads to further demyelination
What are the signs and symptoms of MS?
Motor and sensory problems vary depending on where in the CNS the damage is e.g.
Loss of sensitisation Pain and tingling in localised area Muscle weakness Blurred vision Muscle spasms Ataxia
How can MS present?
Most MS patients will have episodes of neurological deficits - relapses and remissions of neurological symptoms
How will MS patients present at the very start of the onset of the disease?
CIS - a clinically isolated syndrome will generally first present
This is when someone has come and complained of one symptom - these patients have already passes the clinical threshold for the onset of the disease (i.e. if symptoms are presenting, the disease is progressing past the threshold) - dismyelination has started to occur
How can you diagnose MS?
MRI scan (T1 weighted) - look for lesions and demyelination and inflammation (nb. lesions can occur in a range of different places in the brain)
Lumbar puncture - remember MS is disease of the CNS not the PNS
Clinical presentation
Blood tests to rule out any differential diagnoses
NB. Must asses a range of signs and symptoms and a collection of test results before being able to diagnose MS - not just one test
What are the possible differential diagnoses for MS?
Cerebrovascular disease
Syphilis
B12 deficiency
Lyme disease
Where in the brain can lesions occur in MS and how do these present?
Lesions can occur throughout the brain in many different locations - the location of the lesion results in varying symptoms and presentations
What is the most indicative location for a lesion in MS?
A lesion in the corpus callosum is often indicative of MS as lesions in this region are rare in other conditions
At what age do people tend to be diagnosed with MS?
In their 20s/30s
Why may people’s life expectancy be reduced with MS?
Due to the contraction of infections, lifestyle choices, suicide etc rather than due to the actual disease
Give the heirachy of drugs used in the management of MS
Anti-inflammatory drugs
Neuroprotective drugs
Remyelination drugs
Neuro-restoration drugs
What is meant by neuroprotection in the treatment of MS?
Neuroprotective drugs are those that allow for some form of remyelination
How does remyelination occur?
Activation of stem cells which can produce new myeline sheath
Why is the natural process of remyelination not effective in MS?
Chronic condition - continual inflammation and immune response is too much for the remyelination to overcome
