Neuropathology Flashcards
By what routes can MO gain entry into the CNS?
Direct spread = middle ear infection, base of skull fracture
Blood-borne = sepsis, infective endocarditis
Iatrogenic = V-P shunt, surgery, lumbar puncture
What is meningitis?
Inflam of the leptomeninges – 2 inner layers
With/without septicaemia
Prompt diagnosis and treatment is life saving
What organisms can cause meningitis?
Neonates – E. Coli, Listeria. monocytogenes
2 -5 years – H. influenzae type B (HiB)
5 -30 years – N. Meningitides (types)
Over 30 years – S. pneumoniae
Describe chronic meningitis
M. Tuberculosis of the meninges
Granulomatous inflam
Fibrosis of meninges
Nerve entrapment – present with cranial N palseys
Outline the complications of meningitis
Death – swelling = RICP
Cerebral Infarction = neurological deficit
Cerebral abscess
Subdural empyema = diff to treat as no direct blood supply so need to go into surgery
Epilepsy
Systemic = rashes
What is encephalitis?
Brain tissue itself is infected - classically viral
Neuronal death – inclusion bodies
Temporal lobe = herpes virus
Spinal cord motor neurones = polio
Brainstem = rabies
What is a prion?
Protein present in synapses
What is prion disease?
Sporadic mutation – abnormal protein development
Genetic - produce abnormal protein
Become ingested
Normal prions interact with abnormal prions = all become abnormal prions = aggregation = cell death
What is vCJD?
Variant Cretzfeld-Jacob disease
Causes prion disease
Define dementia
Acquired global impairment of intellect, reason and personality without impairment of consciousness
What types of dementia are there?
Alzheimer’s (50%) – Sporadic/Familial, Early/Late
Vascular dementia (20%) = neurones undergo ischaemic damage
Lewy body
Picks disease
What is Alzheimer’s disease?
Loss of cortical neurones at an increased rate = decreased brain weight
Neuronal damage = neurofibrillary tangles of hyperphosphorylated Tau, senile plaques
What mechanisms maintain normal pressure inside the skull?
Reduced blood volume
Reduced CSF volume
Spatial - brain atrophy
Outline the cushing reflex
When ICP raises
The systemic circulation = hypertension in order to delivery enough blood to the brain
Low HR, low RR
May indicate imminent brain herniation
What are space occupying lesions?
Oedema
Tumour
What can result from space occupying lesions?
Deformation or destruction of the brain around the lesion
Displacement of midline structures – loss of symmetry
Brain shift resulting in internal herniation
Outline a subfalcine herniation
Same side as mass
Cingulate gyrus pushed under free edge of the falx cerebri
Ischaemia of medial parts of frontal/parietal lobe and corpus callosum due to compression of anterior cerebral artery = Infarction
Outline a tentorial herniation
Uncus/medial part of the parahippocampal gyrus through the tentorial notch
Damage to occulomotor N on same side (clinical sign)
Occlusion of blood flow in posterior cerebral and superior cerebellar arteries
Online a tonsilar herniation
Cerebellar tonsils pushed into the foramen magnum compressing the brainstem
Why are tumours in the brain rare?
As cells in the brain don’t divide
What types of tumours within the skull can occur?
Meningeal = meningioma (benign)
Astrocyte = astrocytoma
Neurofibroma
Ependymoma
Neuronal = medulloblastoma
Most common = metastasis
How can stroke be categorised?
Infarction = 85%, regional or lacuna (less than 1cm, commonly in the basal ganglia)
Haemorrhage = 15%, intracerebral (hypertensive vessel damage) or subarachnoid (ruptured berry aneurysms)
What are the risk factors for stroke?
Hyperlipidaemia
Hypertension
DM
Vascular disease
Outline the pathogenesis of stroke
Embolism = most common, AT, carotid atheroma, aneurysm
Thrombosis = atheromatous plaque
