Clinical Features of MS Flashcards
Define MS
Chronic, inflammatory, multifocal, demyelinating disease of the CNS of unknown cause
Briefly describe how MS occurs
Autoimmunity -> inflammation -> neurodegeneration (irreversible axonal loss)
Describe the geographical distribution of MS
Latitude effect: the higher the latitude, the higher the incidence and the greater number of MS cases
MS epidemiology in sexes?
More in women than men
MS disease duration
40-50 mean years
Social impact of MS
Only 1 third of patients remain actively employed 15 years after MS onset
Only 1 third of patients remain in a relationship 24 years of MS onset
Describe cognitive impairment in MS
- memory
- speed of information processing
- attention
- executive functioning
Aetiology of MS?
Multifactorial
- genetically susceptible
- environmental factors (latitude, vitamin D, sunlight exposure)
- hormones
- viral infections (EBV)
Evidence of the role of Vit D in MS?
- Low 25 (OH) D serum level-> higher risk of acute attacks
- Low 25 (OH) D serum level -> higher risk of MS
- Low Vit D intake (w/ high latitude) -> higher risk of MS
Potential factors affecting MS incidence?
Latitude effect: greater MS prevalence at higher latitudes; role of Vit D; exceptions to both
Time of exposure: period of susceptibility (<15yrs- original risk & >15 new risk; month of birth effect (May births); more in Spring
Viral Hypothesis: MS triggered by e.g. EBV; more in EBV seropostitive (-ve has 0 risk); higher anti EBV titres has more MS
Genetics: 30% risk, HLA Class II has strongest effect: FHx- 10x risk
Hormones: pregnancy -> less relapses, 3 months post-part has more relapses
Confounding factors for role of Vit D in MS
Black people are more likely to have Vitamin D deficiency, but less likely to develop MS
Confounding evidence to the latitude effect?
- Norway’s North-South gradient is inverted
- Black people are more likely to have Vitamin D deficiency, but less likely to develop MS
Month of Birth effect in MS?
MS higher incidence for May born
Lower incidence for November born
Role of EBV in MS
Similarities in epidemiology:
Young pts (esp women)
High income countries
EBV has a similar latitude distribution
(EBV postive pts are 13x more likely to develop MS)
Confounding evidence to the correlation between EBV and MS
90-95% of world is EBV positive
BUT: MS is virtually absent, among EBV seronegative subjects
Relationship between titres of EBV antibodies and MS?
Higher anti-EBNA IgG titres = higher risk of MS
Relationship between infectious mononucleosis and MS
History of IM = higher risk of MS (2.3 relative risk higher in those with infectious mononucleosis)
Evidence that there are genetic factors for MS
- first degree relatives are 10-25x more likely to develop MS
(HLA-DRB1*15 seems to play a large role)- HLA-clas sII genes have the strongest effect
The role of hormones in MS (2)
- Incidence of MS in women has almost doubled in the last 50 years
- Relapse frequency decreases in pregnancy, but increases in first 3 months post partum
How MS clinically manifests (2)
- Relapses: episodic, acute neuro symptoms lasting over 24 hrs
- Progression: insidious, steady accumulation of irreversible disability for at least 1 yr- needs retrospective assessment (NB: minor/temporary improvement can happen)
Symptoms of relapses (based on lesion location)?
- optic neuritis
- spinal cord lesion: limb weakness, paraesthesia, Lhermitte’s (electric shock), urgency/incontinence, sexual dysfunction
- brainstem lesion: diplopia, paraesthesia, vertigo/nystagmus, dysarthria
- cerebellar lesion: incoordination of limbs, ataxia
- cerebral lesion: impaired conc., hemiparesis, hemisensory, SEIZURES., PSYCH DISTURBANCE
- fatigue
Most common relapse symptoms? (3)
- optic neuritis
- motor weakness
- sensory disturbances
Why are MS symptoms so varied?
Amount and location of damage to nervous system varies between each patient
Subtypes of MS? (3)
and incidence of them
- Relapsing-remitting MS (80-85%)
- Secondary progressive MS (follows RRMS)
- Primary progressive MS (15-20%)
