MS and Alzheimer's Flashcards
Discuss the Epidemiology and prevalence of MS
- affects caucasians more
- females make up 50-75%
- prevalence dependant on latitude
- prevalence in Tasmania is 5 times that of Queensland
* people migrating from areas of increased risk to areas of decreased risk after age of 15 years still have the an increased risk compared to the population in which they now live (vice versa)
* cooler climate
- prevalence in Tasmania is 5 times that of Queensland
- genetics:
- immediate family members suffering = 7 times the risk
- identical twins concordance rates 20-35%
- increased risk in carriers of the HLA-DRB1 genes
- dizygous twins only 2-3%
- epigenetic factors i.e. environmental modification of genotype
Discuss aetiology and pathogenesis of MS (write notes on the MS plaque)
Causes:
- hep B vaccine
- viral infections i.e. EBV
- CSF insufficiency/toxins
- vitamin D deficiency (correlation with geographical location; + Vit D is important as it decreases production of pro inflammatory cytokines and increases production of anti-inflammatory cytokines)
- genetics
- geographical location
Pathogenesis:
characteristic lesion in Ms is the ‘plaque’ i.e. area of demyelination
Acute plaque
- involves perivascular infiltrates of monocytes and lymphocytes
1. an acute plaque is a lesion developing during an acute inflammatory immune mediated response
2. target tissue is the oligodendrocyte and myelin produced by them –> demyelination impairs nerve function and the exposed axons are subject to damage by inflammatory process
3. following demyelination spontaneous demyelination occurs but is often incomplete. With continued episodes more oligodendrocytes are killed demyelination fails leading to damage and degeneration of axons
features:
- 0.1mm to serveral CM in diameter
- plaque soft and pink
- ill defined borders
- oedema
- perivasc infiltration and accumulation of inflamm cells
- breakdown of myeline and phagocytosis by macrophages
Chronic plaque
lesion resulting when inflammation ceases
1. reactive fibrillary gliosis occurs (reactive CNS scar tissue when astrocytes enlarge and fill gaps)
2. sharply defined, grey/translucent areas of demyelination
3. few/absent/no oligodendrocytes
4. subsidence of perivascular infiltrates
most common sites = white matter of brain and SC plus optic nerve, cerebellar peduncles, dorsal and lateral spinal tracts
What are the most common sites for plaque development
White matter of brain and SC plus optic nerve, cerebellar peduncles, dorsal and lateral spinal tracts
periventricular areas of CNS
Which are the most common presenting ssx of MS?
- limb weakness
- paraesthesia
- optic neuritis
- diplopia
- bladder dysfunction
- vertigo
Most common signs overall
?
Most common symptoms overall
?
list 5 sex that are extremely characteristic of MS. Briefly describe each manifestation
- lateral internuclear ophthalmoplegia
- bilateral internuclear ophthalmoplegia
- Lhermitte’s sign (electric shock to limbs when flexed)
- Marked exacerbation of ssx when febrile (or occurrence of new ssx)
- retrobulbar neuritis
How is MS diagnosed?
Clinical manifestations, clinical progression, and variety of diagnostic investigations
incl. electrophysiological studies, CT/MRI (shows oedema especially in periventricular areas), oligoclonal bands in CSF examination
Discuss the clinical course of MS
Definite MS:
• Consistent course (relapsing/remitting) with >2 bouts, separated by >1 month; or slow, stepwise Progressive course for at least 6 months
• Documented neurologic signs of lesions in >1 area of the CNS
• Onset of Symptoms between 10 and 50 years of age
• Absence of other more likely Neurologic explanation
Probable MS:
• History of Relapsing/Remitting Symptoms
• Signs not documented and only one current Sign, commonly associated with MS
• Documented single bout of symptoms with signs; >1 White Matter Lesion
• Good recovery, then variable Symptoms and Signs
• Absence of other more likely Neurologic explanation
Possible MS:
• History of Relapsing/Remitting Symptoms
• No documentation of Signs establishing more than one White Matter Lesion
• Absence of other more likely Neurologic explanation
OR
Severe disease: rapid progression of disease - 5% of patients, death in <5yrs
Moderate disease: gradual progression - 80% of pt.s, episodes 1-2 years
Mild disease: One or few episodes, 15% of patients
Prognosis of MS
On average a patient will live 20 years following onset
Events associated with better prognosis:
- onset with sensory ssx
- onset in middle age
Events associated with poorer prognosis:
- onset with motor ssx
- onset at earlier age
List the complications of MS,
Why do they occur?
- UTI
- Chest infections
- Pressure sores
- Acute rest failure due to weakness of ventilatory mm
as a result of being bed ridden - later stages of disease (usually responsible for death)
Define Dementia
organic loss of neurons in the cerebral cortex
diffuse degeneration of cerebral tissue
associated decrease in functional capacity of the tissue
Aetiology of dementia
HIV ISOL hydrocephalus drugs/toxins vitamin deficiency
Define Alzheimer’s dementia
Clinicopathological entity
condition defined by a specific pattern of cognitive changes and structural/biological changes.
most common form of dementia
Is it a common condition?
Fairly yes
Affects 100,000 ppl in Aus
Makes up 50% of all cases of dementia
