MS Flashcards
What is multiple sclerosis (MS)?
An inflammatory, demyelinating, auto immune disease of the central nervous system (CNS) which can affect the brain, spinal cord and optic nerve.
What are the causes of MS? (6)
Obesity
smoking
lack of vitamin D
contact with a virus (Epstein-Barr virus) which triggers an auto-immune response
migration from low-risk to high risk area before puberty
genetics (1st degree relatives)
What is the pathophysiology behind MS?
- Genetic susceptibility + exposure to an environmental agent in childhood induces auto-reactive T-cells (T cells normally play a crucial immune-defence role, but in auto-immune diseases)
- Latent period (10-20 years)
- Systemic trigger (viral infection) activates the auto-reactive T-cells
- Auto-reactive T-cells cross the BBB and on re-exposure to their antigen initiate a cell mediated inflammatory reaction
- The inflammation results in demyelination and axonal loss
- CNS antigens, released as a result of tissue damage, initiate further episodes of auto-immune induced inflammation
- Focal inflammation causes axonal toxicity, demyelination and conduction block
- Persistent demyelination results in gradual loss of axons resulting in the development of progressive neurological impairment.
How does ‘recovery’ occur in MS?
Axonal plasticity (recovery) i.e. the synthesis of sodium channels in demyelinated nerve segments or re-myelination in conjunction with grey matter plasticity results in functional recovery.
What do the symptoms of MS depend on in the patient?
The site and size of the lesion(s), the integrity of the neuronal pathway and whether or not there has been any regeneration.
What are the 4 subtypes of MS?
Clinically Isolated Syndrome (CIS), Relapsing-remitting MS (RRMS), Secondary Progressive (SPMS), Primary Progressive (PPMS)
Initial symptoms of MS?
Ataxia (lack of muscle control or co-ordination of voluntary muscle movement)
Lethargy & fatigue
gait instability & impaired balance,
sensory disturbances (pins & needles or numbness)
vestibular problems
weakness/diminished dexterity in one or more limb,
optic neuritis or other visual disturbances (blurring, double vision)
Symptoms as the condition progresses?
Bladder dysfunction, fatigue, heat sensitivity, depression, cognitive impairments (impaired attention/problem solving, memory loss, slower information processing and difficulty shifting between cognitive tasks)
Define primary progressive MS (PPMS)
There are no noticeable periods of relapse. PPMS can be classified as to whether it is “active” (when there are worsening signs on MRI and/or there may be an occasional rare relapse) or “not active”; additionally, it can be classified as to whether it is “with progression” (increased disability over time with or without relapse, or new worsening signs on MRI) or “without progression”.
Define Clinically-isolated syndrome
A single episode of MS where the CNS symptoms last for a minimum of 24 hrs, from which the majority of people make a full (or almost) recovery. The prognosis for those without signs of MS on MRI scanning is much more positive, with less than 20% going on to develop MS.
Define relapse-remitting MS (RRMS).
Most common type of MS, accounts for 85% of cases. Patients with this type of MS experience acute attacks (exacerbations/relapses) once or twice/year. A relapse can last from days to months and is followed by a period of remission with complete or partial recovery. Between these periods patients may be clinically stable.
Define the 3 classifications of RRMS
- Active -> when relapses/exacerbations occur or there are worsening signs on MRI
- Not active
- Worsening -> when after an active attack/ relapse and remission, the person does not return to their previous level of ability
- Not worsening
Define Secondary Progressive MS (SPMS)
Majority of people with RRMS convert to SPMS within 10-15 years of disease onset with gradual progression of disability with/without relapses. SPMS is classified into active, not active, with progression, without progression. People in this stage of MS, do not suffer from much inflammation (the disability they suffer is due to tissue damage sustained earlier in the disease course) and therefore there is less response to disease modifying medication. This stage is characterised by generalised brain atrophy.
What factors are associated with a greater risk of disability with MS?
Low vitamin D blood serum levels, shorter intervals between relapses, incomplete recovery, greater number and volume of lesions during the first 2years, being male, older at age of diagnosis of MS, evidence (on MRI) of brain atrophy
What are good prognostic signs with MS?
Female, full recovery from 1st attack, being a younger age at onset, infrequent relapses, low baseline lesion load on MRI
