11. Neuropathology Flashcards
What are the three routes microorganisms can gain entry to the CNS via?
Direct spread, blood-borne, iatrogenic.
What is meningitis?
The inflammation of the leptomeninges - pia and arachnoid, with or without septicaemia.
What are the likely causative organisms of meningitis in neonates?
E. coli, L. monocytogenes.
What are the likely causative organisms of meningitis in 2-5 year olds?
H. influenzae type B.
What are the likely causative organisms of meningitis in 5-30 year olds?
N. meningitides.
What are the likely causative organisms of meningitis in people over 30 years old?
S. pneumoniae.
What is chronic meningitis cause by?
M. tuberculosis.
What is chronic meningitis?
Chronic clinical course with granulomatous inflammation, fibrosis of meninges, and nerve entrapment.
What are the local complications of meningitis?
Death from RICP due to swelling, cerebral infarction causing neurological deficit, cerebral abscess, subdural empyema, epilepsy.
What is encephalitis?
A viral infection of the parenchyma which causes neuronal cell death.
What is the result of encephalitis considering the temporal lobe, spinal cord motor neurones, brain stem, and lymphocytic inflammatory reaction?
Temp - epilepsy. Spinal cord - MN signs. Brain stem - quick fatality. Lymph - swollen brain so RICP and death.
What causes encephalitis of the: temporal lobe, spinal cord motor neurones, and brain stem?
Temp - herpes virus, SC - polio, brain stem - rabies.
What is the histological presentation of cytomegalovirus?
Owl’s eyes.
Which patients suffer from CMV?
HIV and AIDS immunocompromised patients.
What are prions?
Proteins that are part of the normal constituent of synapses.
How can prion proteins become mutated?
Sporadic, familial or ingested.
What is the pathophysiology of prions disease?
Prion proteins aggregate and cause neuronal death so holes form in grey matter.
What is variable Creutzfeld-Jacob disease an example of?
A spongiform encephalopathy.
What is dementia?
Acquired global impairment of intellect, reason, and personality without impairment of consciousness.
What are the types of dementia?
Alzheimers, vascular, Lewy body, and Picks disease.
What are the features of Alzheimer’s disease?
Loss of cortical neurones (decreased brain weight, cortical atrophy) due to increased neuronal damage.
What can neuronal damage be due to in Alzheimer’s disease?
Neurofibrillary tangles and senile plaques.
What are neurofibrillary tangles?
Intracellular twisted filaments of Tau protein. Tau is hyperphosphorylated.
What are senile plaques?
Foci of enlarged axons, synaptic terminals and dendrites with amyloid deposits in vessels in the centre of plaques.
Which mutations of chromosome 21 cause early onset AD with Down’s syndrome?
Amyloid precursor protein gene, presenilin genes 1 and 2 code for components of secretase enzymes, lead to incomplete breakdown of APP and amyloid is deposited.
What is normal intracranial pressure?
0-10mmHg.
What are the compensation mechanisms involved in maintaining normal intracranial pressure?
Reduced blood volume, reduced CSF volume, spatial-brain atrophy.
What are the consequences of expanding lesions in the cranium?
Deformation or destruction of the brain around the lesion, displacement of midlines structures, brain shift can cause internal herniation.
What is a subfalcine herniation?
On same side as mass, cingulate gyrus is pushed under the free edge of the falx cerebri.
How can subfalcine hernias cause infarction?
Ischaemia of medial parts of the frontal and parietal lobe and corpus callosum due to compression of anterior cerebral artery -> infarction.
What is a tentorial herniation?
Uncus/medial part of parahippocampal gyrus herniates through tentorial notch.
How do tentorial hernias cause dilated pupils?
Damages oculomotor nerve on the same side.
How are tentorial hernias frequently fatal?
Secondary haemorrhage into brainstem -> duret haemorrhage.
How can tentoral hernias cause infarction?
Occludes blood flow in posterior cerebral and superior cerebellar arteries.
What is a tonsilar herniation?
Cerebellar tonsils are pushed into foramen magnum, compressing the brainstem.
What is a benign tumour of the brain?
Meningioma.
What is a malignant brain tumour?
Astrocytoma.
Name a tumour of the brain from non-CNS tissues.
Lymphoma, metastasis.
What is a stroke?
Sudden event producing a disturbance of CNS function due to vascular disease.
What are the two categories of stroke?
Cerebral infarction (85%) and cerebral haemorrhage (15%).
What is the pathogenesis of strokes?
Embolism or thrombosis.
What are the types of cerebral infarct?
Regional and lacuna.
What are the two common haemorrhages in cerebral haemorrhage strokes?
Intracerebral and subarachnoid.
What is intracerebral haemorrhage associated with?
Hypertensive vessel damage, Charcot-Bouchard aneurysms, deposition of amyloid around cerebral vessels in the elderly.
What causes subarachnoid haemorrhages?
Rupture of berry aneurysms.
Where are berry aneurysms found?
Circle of Willis.
What is the presentation of subarachoid haemorrhages?
Sudden severe headache (thunderclap), sentinel headache (build up from small bleeds), loss of consciousness. Instantly fatal.
