Brain pathology + other disorders Flashcards
What 3 ways can infection enter the brain?
- Direct spread from middle ear infection or basilar skull fracture
- Blood borne (sepsis, infective endocarditis)
- Iatrogenic (lumbar puncture, surgery)
What is meningitis the inflammation of?
The leptomeninges- pia and arachnoid not dura.
What organism is most likely to cause meningitis in a neonate?
e coli or l. monocytogenes
What organism is most likely to cause meningitis in a 2-5 yr old?
H. influenza
What organism is most likely to cause meningitis in a >30 yr old?
s. pneumonia
Give 4 complications of meningitis
- Brain damage due to swelling and raised ICP
- Death due to brain damage
- Cerebral abscess (needs surgical treatment)
- subdural empyema
- epilepsy
What causes chronic meningitis?
M. tuberculosis - granulomatous inflammation is seen
What is the result of chronic meningitis?
Fibrosis, leading to entrapment of nerves leading to cranial nerve palsies
What is the most likely cause of temporal lobe encephalitis, spinal cord motor neurone and brain stem encephalitis?
Temporal lobe= a herpes virus (eg cytomegalovirus)
Spinal cord motor neurone= polio
Brain stem= rabies
How does encephalitis present?
Headaches, nausea, photophobia etc, usually in an immunocompromised or herpes pt
How do prions cause disease?
The mutated prions cause other normal prions to change conformation to be like the mutated ones, which aggregate and accumulate in neurones and cause neuronal death. This gives the brain a spongey appearance.
Give 2 examples of prion diseases?
varient cretuzfelt jacob disease, scapie in sheep, BSE in cow, Kuru in tribes of new guinea
What are the 4 types of dementia? Give in order of prevelance
- alzheimers (50%)- can be sporadic or famillial and early or late (late sporadic most common)
- vascular dementia (20%)
- lewy body
- frontotemporal dementia
Describe the pathogenesis of alzheimers dementia?
Tau protein (which normally binds and stabilises microtubules) becomes hyperphosphylated and so aggregates and causes neuronal cell death. The dead neurones full of tau aggregate to form senile plaques. Amyloid is deposited in the vessels at the centre of the plaques. This leads to loss of cortical neurones, which causes the decline in brain function.
What is the most common type of brain tumour in adults?
meningioma
What is the most common malignant brain tumour?
astrocytoma
Define dementia?
progressive decline in higher cortical function leading to a global impairment of memory, intellect and personality which effects the individuals ability to cope with activities of daily living.
Give 3 reversible causes of dementia?
depression, trauma, vitamin deficiency, alcohol, thyroid disorders.
Give 4 presentations of dementia?
- memory deficit
- behavioural- altered personality, disinhibition, labile emotions, wandering
- physcial- incontinence, reduced oral intake, difficulty swallowing, apraxia (difficulty with motor planning)
- language disorder- difficult understanding, anomic aphasia (loss of word retreival)
- visuospatial disorder- unable to identify visual and spatial relationships between objects
How would dementia be investigated?
- history + collateral history +mini mental state exam
- full neurological exam
- blood tests for reversible causes- B12, TFTs
- CT/ MRI head
- memory clinic follow up
What may a CT of dementia show?
- may be normal
- may show ventricle dilation and generalised atrophy
What may an MRI of dementia show?
Axial and coronal sections of T1 may show hippocampus atrophy
How can you differentiate between delirium and dementia?
CAM score of >2= delirium:
- Acute change or fluctuating mental status
- altered consciousness (hypo or hyperactive)
- inattention (can they count from 20-0)
- disorganised thinking
Describe the pattern of mental status decline over time for alzheimers disease?
Generally steady decline as time goes on