Dementia Flashcards
Which part of the brain would be atrophied in a patient with Alzheimers
The hippocampus (memory formation)
Hallmark pathology of Alzheimers
Beta amyloid plaques and neurofilibary tangles composed of tau protein (predominantly affecting the hippocampus)
Macroscopic brain changes of Alzheimers
- Cortical atrophy (shrinkage of cortical gyri and widening of sulci) - predominantly the hippocampus, the parahippocampal gyrus, and the temporal amygdala, with parietal and frontal lobes being next most severely affected. The occipital lobe is generally spared.
- Low brain weight
- Ventricular dilation, generally of moderate degree, parallels the severity of the cortical atrophy
- Depigmentation of the locus coeruleus in the face of relative preservation of the substantia nigra is also typical
Describe a Hirano body
Hirano bodies are actin-rich, eosinophilic (they stain with the bright pink dye eosin) intracytoplasmic inclusions which have a highly characteristic crystalloid fine structure. They are regarded as a non-specific manifestation of neuronal degeneration.
What is the difference between Hirano bodies and Lewy bodies?
Lewy bodies contain ubiquitin whereas Hirano bodies do not
What is the signifcance of the nucleus basalis in Alzheimers
It is a somewhat diffuse collection of large cholinergic neurons in the basal forebrain that degenerates in Alzheimers resulting in a decrease in acetylcholine in the brain.
What are the characteristic signs of Parkinsons disease?
Bradykinesia
Rigidity
Resting tremor
Postural instability
What are the characteristic signs of Huntington’s disease?
Chorea
Cognitive decline
Psychiatric symptoms
What is dementia pugilistica?
Chronic traumatic encephalopathy (CTE), neurodegenerative disease associated with repeated head trauma.
Presents with cognitive impairment, behavioural change and at times Parkinsonism
Neuropathology of CTE
Many neuropathological abnormalities have been identified in CTE.
The most unique feature is the abnormal accumulation of tau in neurons and glia in an irregular, focal, perivascular distribution and at the depths of cortical sulci.
Note: tau accumulations are also seen in Alzheimer’s and in normal aging but in CTE, the distribution of these is unique with them tending to be localised around vessels and in depths of sulci.
Abnormalities of the septum pellucidum (cavum, fenestration) are also a common feature.
What are the macroscopic brain changes associated with Lewy Body dementia?
- Cerebral atrophy (less marked than in Alzheimers)
- Pallor of the substantia nigra and locus coeruleus
What are the microscopic brain changes associated with Lewy Body dementia?
- Intracellular protein accumulations called ‘Lewy bodies’. Primarily containing alpha synuclein. They are found mainly within the brainstem in Parkinson’s disease but are found in non-brainstem regions in Lewy body dementia (typically amygdaloid nucleus, parahippocampal gyrus, cingulate cortex, and cerebral neocortex).
- Neurofibrillary tangles and senile plaques
- Neuronal loss and gliosis are usually restricted to brainstem regions, particularly the substantia nigra and locus ceruleus.
What are the microscopic brain changes in Alzheimers
- Senile plaques (extracellular deposits of beta amyloid in the gray matter of the brain)
- Neurofibrillary tangles
- Gliosis
- Degeneration of the nucleus of Meynert (nucleus basalis)
- Hirano bodies
What proportion of Alzheimers cases are early-onset (<65yo)?
0.1%
Describe Argyll-Robertson pupils?
Small and irregular pupils with impaired reaction to light but normal reaction to accommodation.
Dilation of the Argyll Robertson pupil is typically poor with mydriatic agents.
Pathognomic of tertiary syphillis
Describe the EEG that would be seen in Huntingtons disease
Flattened trace
What is Multisystem Atrophy?
A Parkinson plus syndrome characterised by:
- Parkinsonism
- Autonomic failure
- Cerebellar ataxia
What are the macroscopic features of Multisystem Atrophy?
- Pallor of substantia nigra
- Greenish discolouration and atrophy of the putamen
- Cerebellar atrophy
