Multiple Sclerosis and Alzheimers Flashcards
Discuss the aetiology of MS
Aetiology (main theories): Abnormality in Myelin Autoimmune disorder (viral?) circulating CSF toxins Viral infection of CNS Genetic Slow virus @ childhood = autoimmune mediated CNS damage in genetically predisposed people
Write notes on MS Plaque
2 phases:
1) acute plaque formation 2)Chronic plaque formation
APF - lesion forms (inflammatory) 0.1 - several cm in D @ periventricular areas CNS Soft and Pink Ill defined borders breakdown of myelin & Phagocytosis by macrophages Odema Periventricular infiltration and accumulation of inflam cells (T, plasma)
CPF - inflam subsides reactive fibrillary gliosis sharply defined, grey/translucent areas of demyelination few/absent oligodendrocytes Subsidence of perivent infill
what are the most common sites for development of plaque.
a) optic nerves
b) brain stem
c) cerebellar peduncles
d) dorsal and lateral (pyramidal) spinal tracts
What are the most common presenting signs and symptoms?
limb weakness 40-50% Paraestesia 20% Optic neuritis 20% diplopia 10% bladder dysfunction 5% vertigo 5%
List 5 signs or Symptoms which are considerered characteristic of MS: explain
Lateral internuclear ophthalmoplegia (damage to the medial longitudinal fasciculus which connects CN 3 & 6 in the brainstem) - eyes move dysjuctively during lateral gaze
Bilateral internuclear ophthalmoplegia
Lhermitte’s sign - electric shock radiating to limbs initiated by neck flexion
Retrobulbar neuritis - 50% of patitents with this develop MS
Marked exacerbations or appearance of previously undetected ssx when body temp is raised.
How is MS diagnosed? 5 points
- Electrophysiological studies: delayed nerve conduction ie abnormal visual/auditory evoked potentials. visual = 95% positive (sensitive) but not specific
- CSF - normal to mild increase n lymphocytes. Slightly increased protein.
Electrophoresis: oligoclonal Abs and increased IgG - CT scans show hydrodense areas of demyelination
- MRI shows area of increased (bright) signals
- Clinical picture is important, need 2 characteristic episodes to make a clinical diagnosis
Discuss the clinical course of MS
Extremely Variable:
Mild: 15% of patients
one or a few episodes
complete recovery occurs with no further relapses
Moderate: 80% of paitents
- progresses over decades.
- incomplete recovery from each episode of demylin.
- gradual CNS damage
- attacks average 1 every 2 years
Discuss the prognosis of MS (5 points)
- average life expectancy = 20 years post onset.
- % still fully functional x years after 1st attack:
- 60%, 10years
- 25-30%, 30 years - Better prog if onset:
- sensory manifestations
- middle age - Worse prog if onset:
- motor manifestations
- early age <20yrs - Life expectancy is mildly decreased.
Complications of MS. Why?
Due to being bed ridden: UTIs Chest infections pressure sores etc or Death during acute phase
Define Dementia
“organic” loss of intellectual functions
briefly discuss the aetiology of dementia
- affects 15% adults >70yrs
- Associated with many conditions
Primary degen disorders:
-Alzheimers Disease
- Picks Disease
- Huntingtons Disease
- Parkinson’s Disease
Disorders causing 2ndry CNS changes = dementia
- cerebrovascular disease
- infections (HIV, syphilis)
- isols
- hydrocephalus
- drugs/toxins (alcohol etc)
- metabolic diseases
- vitamin defs
- paraneoplastic syndromes
Define the term Alzheimers Disease. Is it common?
Alzheimers disease is characterised by the progressive loss of neurons in the entire Cerebral Cortex.
Most common form of dementia in straya.
Discuss the macroscopic changes which occur in the brains of Alzheimer’s dementia patients.
macroscopic changes
- brain weight is decreased
- cortical atrophy (especially frontal and temporal lobes)
- loss of grey & white matter
- secondary hydrocephalus
- hind brain/spinal cord look normal
List the three main histological features of Alzheimer’s disease
microscopic changes
- most pronounced in cerebral cortex
- clinical severity reflects the histological severity
- diffuse neuronal loss
Briefly discuss the pathogenesis of:
i. Senile (neuritic) plaques
ii. Neurofibrillary tangles
iii. Diffuse neuronal loss
i. Mainly hippocampus (also in other areas of cortex and deep grey matter)
- up to 200 nanometres in diameter
- initially is a collection of dilated pre-synaptic neuronal processes which contain many organelles
- Maturation =
enlargement
degeneration of the neuronal processes
core of aluminosilicates and amyloid protein develops
reactive astrocytes and microglia collect at the periphery of the plaque
- burnt out phase of plaque development:
neuronal processes
= degen completely
the plaque is an extracellular collection of amyloid protein.
ii. Neurofibrillary tangles
- appear in the cytoplasm of neurons
- mostly hippocampal neurons (occur in other parts of CNS also)
- changes:
thickening of fibrils in the neuronal cytoplasm
the fibrils form tortuous, elongated, cork-screw like structures
the fibrils resemble neurofilament and microtubule associated proteins.
iii. Diffuse Neuronal Loss.
