MS Flashcards
Define MS
progressive long term neurological disorder of CNS affecting brain SC and optic nerves
acquired chronic autoimmune mediated inflammatory disease
multiple areas of scarring sclerotic tissue found disseminated throughout the CNS white and grey matter
BS SC optic nerve
prevalance
MS is the most prevalent chronic inflammatory disease of the CNS and the most common cause of non-traumatic neurological disability in young adults:
8,000 people living with MS in Ireland
100,000 people in the UK
400,000 people in the US
2.5 million people worldwide
Globally, the median estimated prevalence of MS is 30 per 100,000
(range, 2–80)
epidemiology
Peak age onset 25-35 years 70% between 21 and 40
Rarely in childhood and after 60 years
Females > Males (3:1)
White races mostly
Risk 1:750-800 for Northern Europeans
causes
not known if it has single or multiple causes known risk factors genetic environmental viral immunological
genetic factors
Incidence in first-degree relatives is 20 x higher than in general population (2-4% compared to 0.1%)
Risk higher for females
Concordance rate in monozygotic twins is 30%
Women transmit to offspring more frequently than males
Genome-wide association studies from 1000s of patients have
identified >200 gene variants that raise the risk of disease
Most risk alleles are associated with immune-pathway genes
environmental factors
Incidence higher with increasing geographic latitude
Europe and North America – 120 per 100,000 population (4-6x higher than south)
Equatorial countries – rare (1 per 100,000)
Differences in the same latitude – lower prevalence in Korea compared to Japan
Reasons unclear
viral factors
“Epidemics” after WWII Faroe Islands
Orkney and Shetland Islands
Iceland
Viral agent with long incubation period?
Increased incidence after history of mononucleosis or Epstein- Barr virus?
No proof
immunology
Genetically susceptible individuals may have an abnormality in immune response that results in an attack on their own neural tissue
Analysis of active lesions suggests that a single immune- effector mechanism dominates in each person
No single specific antigen
pathophysiology
MS attacks myelin in the CNS
Complex interplay between the immune system, glial cells
(myelin-making oligodendrocytes) and neurons
Destruction of oligodendrocytes → Myelin degenerates → Less
effective conduction by neuron
pathology
Sclerotic plaques in the cortex (grey and white matter), spinal cord and optic nerve
Acute lesions are inflammatory, mediated by T cells (CD4+ and
CD8+)
Relative sparing of axon itself initially
Possible incomplete re-myelination following acute demyelinating episode
Later stages of disease: damage to axons
investigations
no single definitive test
lumbar puncture
visual evoked response
MRI
clinical presentation
initial symptoms
Vague: lack of energy, headache, depression, aches in limbs
Precise neurological deficit Sensory disturbance 40% Retrobulbar or optic neuritis 17% Limb weakness 12%
Diplopia 11%
Vertigo, Ataxia, Sphincter disturbance - 20%
FCDE: First clinical demyelinating event
clinical symptoms
motor symptoms and signs
Muscle weakness: Often asymmetric paraparesis Monoparesis Hemiparesis Tetraparesis Spasticity (80%) Clonus Spasms Hyperreflexia, positive Babinski’s sign Abnormal posture and movement
visual symptoms
diplopia
blurred vision
loss of visual activity
sudden onset of optic neuritis without any other CNS signs or symptoms
pupillary abnormalities
irregularities in outline of pupil
partial constriction and loss of light reflex
cerebellar signs
hypotonia ataxia intention tremor poor coordination nystagmus dysarthria
