Extra Neurology Flashcards
TIA
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Pathophysiology
The commonest cause of a TIA is cerebral ischaemia resulting in a lack of O2 and nutrients to the brain resulting in cerebral dysfunction - however in a TIA this period of ischaemia is short-lived, with symptoms usually only lasting a maximum of 5-15 minutes after onset, and then resolves with before irreversible cell death occurs
Symptoms that gradually progress suggest a different pathology such as demyelination, tumour or migraine
Cerebral amyloid angiopathy can lead to HAEMORRHAGIC STROKE what is it?
Deposition of amyloid-B in the walls of small and medium-seized arteries in normotensive patients - particularly over 60 results in lobar intercerebral haemorrhage
Common causes for strokes in young people?
- Vasculitis
- Thrombophilia
- Subarachnoid haemorrhage
- Carotid artery dissection - spontaneous, or from neck trauma
- Venous sinus thrombosis:
Common causes for strokes in older people?
- Thrombosis in situ
- Athero-thromboembolism
- Heart emboli e.g. AF, infective endocarditis or MI
- CNS bleed
- Sudden BP drop by more than 40mmHg
- Vasculitis
- Venous sinus thrombosis
Where are ruptures of a Berry aneurysm that cause a SAH common?
Rupture of the junction of the posterior communicating artery with the internal carotid or of the anterior communicating artery with the anterior cerebral artery - in the circle of Willis
15% are multiple i.e. multiple aneurysms
Associated with; polycystic kidney disease and coarctation of the aorta (narrowing of aorta where ductus arteriosus is)
How does Atriovenous malformations cause SAH.
• Vascular developmental malformation often with a fistula between arterial and venous systems causing high flow through the AVM and high-pressure arterialisation of draining veins
Rare causes of SAH
- Bleeding disorders
- Mycotic aneurysms -endocarditis
- Acute bacterial meningitis
- Tumours
What is kernig’s sign?
Kernig’s sign is one of the physically demonstratable symptoms of meningitis. Severe stiffness of the hamstrings causes an inability to straighten the ug when the hips is flexed.
1 . knee is flexed to 90 degrees
2. Hip flexed to 90 degrees
3. Extension of the knew is painful or limited in extension
Brudzinski sign
Physically demonstrable symptoms of meningitis. Severe neck stiffness causes a patients hips and knees to flex when the neck is flexed.
Pathophysiology of migraines
- Genetic and environmental factors play a role
- Genetic factors play a role in causing neuronal-hyper-excitability
- Changes in brainstem blood flow lead to an unstable trigeminal nerve nucleus and nuclei in the basal thalamus
- Cortical spreading depression - self-propagating wave of neuronal and glial depolarisation that spreads across the cerebral cortex is thought to cause the aura of migraine and leads to the release of inflammatory mediators which impact on the trigeminal nerve nucleus
- This results in release of vasoactive neuropeptides including calcitonin-gene- related peptide (CGRP) and substance P; this then results in the process of neurogenic inflammation - vasodilation and plasma protein extravasation - leading to pain that propagates all over the cerebral cortex
MENINGITIS
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Pathophysiology of meningitis
MO reach the meninges either by direct extension from the ears, nasopharynx, cranial injury or congenital meningeal defect or by blood stream spread. Once you get the bacteria in the CSF it can multiply very quickly as there are no immune cells, this causes inflammation of the meninges and breaking down of the BBB and the WBC (neutrophil polymorphs) get in leading to even more inflammation.
Infection🡪 Inflammation🡪 Neurological signs
Cerebral oedema🡪Raised ICP🡪 Neuronal death
A layer of pus forms 🡪 adhesions 🡪 cranial nerve palsies and hydrocephalus
What can you see in chronic infection e.g. TB?
The brain is covered in a viscous grey-green exudate with numerous meningeal tubercles.
ABCDE management
Airway, Breathing, Circulation, Disability, Exposure
