Neuropathology Flashcards
What are the three possible routes of which microorganisms can enter the CNS?
Direct spread - middle ear infections, basal skull fractures
Blood-borne - sepsis, infective, endocarditis
Iatrogenic - V-P-shunt, surgery, lubar puncture
What is meningitis?
Meningitis is inflammation of the leoptomeninges
With or without septicaemia (sepsis is the more dangerous bit)
Prompt diagnosis and treatment is lifesaving. (Sometimes treat before knowing exact organism)
What are the common causative organisms of bacterial meningitis?
Neonates - E. Coli, L. Monocytogenes
2-5yrs - H. Influenzae type B
5-30 - N. Meningitides (types)
Over 30 - S. pneumoniae
Various in immunocompromised patients
What is the most common causative organism of chronic meningitis? How does it present?
Chronic clinical course
Not complain of some types of symptoms - more subtle.
M. Tuberculosis most common cause.
Granulomatous inflammation
Fibrosis of meninges
Nerve entrapment
What are the complications of meningitis?
Local: Death (swelling - RICP) Cerebral infarction - neurological deficit Cerebral abscess Subdural empyema Epilepsy
Systemic - associated with sepsis
What is encephalitis?
Classically viral not bacterial
It affects the parenchyma not meninges
Neuronal cell death by virus - inclusion bodies.
Virus kills neurones causing inflammation and presence of intracellular viral inclusions. Lymphocytic infiltrate typical
How does the organism change the area of the brain affected by encephalitis?
Temporal lobe - Herpes
Spinal cord motor neurones - Polio (eradicated)
Brainstem - Rabies (rare)
What are prions?
Misfolded proteins.
The key component of prions is the prion protein (PrP)
Normal constituents of synapses?
How do you get mutated prion proteins?
Mutated PrP can be sporadic, familial or ingested.
Mutated PrP interacts with normal PrP to undergo a post translational conformation change.
This is an extremely stable structure.
What happens in a dense caused by Prions? What diseases are caused by prions?
PrPsc aggregates - neuronal death and holes in great matter.
Spongiform encephalopathies: Scrapie in sheep BSE in cows Kuru in tribes of New Guinea Variant Creutzfeld-Jacob disease (vCJD)
What is vCJD?
Variant Creutzfeld-Jacob disease
First described in 1996 in UK
Different from classical CJD
Each case has unique prion sequence
Strong lab and epidemiological evidence of causal association of vCJD with BSE. -caused by eating meat of cows infected with BSE.
What is dementia?
Acquired global impairment of intellect reason and personality without impairment of consciousness.
What are the common types of dementia?
Alzheimer’s
Vascular dementia
Lewy body
Pick’’s disease
What is Alzheimer’s disease
Exaggerated ageing process
Loss of cortical neurones -decrease brain weight and cortical atrophy.
Die to increased neuronal damage - neurofibrillary tangles and senile plaques.
What are neurofibrillary tangles?
Intracellular twisted filaments of Tau proteins.
Tau normally binds and stabilises microtubules.
Tau becomes hyperphosphorylated
“Taupathy”