Neuro: Stroke

Define what a stroke is:

• stroke is a neurological deficit attributed to an acute focal injury of the CNS by a vascular cause

List the vessels that comprise the Circle of Willis:

1. Anterior communicating artery

2. Anterior cerebral arteries (branches of the ICA)

3. Internal carotid arteries (continues as middle cerebral artery)

4. Posterior communicating arteries

5. Posterior cerebral arteries (terminal branches of the basilar artery)

List the Anterior circulation for the circle of willis

• anterior cerebral arteries

• anterior communicating artery

• middle cerebral arteries

List the arteries in the posterior circulation of the circle of willis

• posterior cerebral arteries

• posterior communicating arteries

What forms the basilar artery?

• the union of the verteral arteries

Give an example of a large blood vessel of the brain

• Internal carotid

Give an example of a small blood vessel to the brain

• lenticulostriate arteries

What is an ischaemic stroke?

• stroke caused by a blockage of a blood vessel in the brain

How are large blood vessels of the brain blocked?

• blood clot travelling from body up into the brain

• blood vessel narrows and clot becomes stuck, limiting blood flow to surrounding brain tissue

What is the medical term for a blood clot stuck in a large blood vessel of the brain?

atherosclerosis

What is a cardioembolism?

• blood clots forming within the heart chambers dislodge and migrate into the cerebral arterial circulation

What is an artery-artery embolism?

• plaque in proximal large arteries sheds microemboli that travel distally to block smaller downstream branches

What is an in-situ atherothrombosis?

• atherosclerotic plaque directly within a cerebral artery ruptures or expands, forming a local thrombus that occludes the vessel at that exact site

What is an arterial dissection?

• a structural tear in the tunica intima of blood vessel

• causes an intramural haemotoma and thrombus within the arterial wall

How can strokes be caused by small vessels of the brain?

• small blood vessels do not get clots as they are too small for clots to travel in them

• occlusions occur instead

• lacunar infarcts affect deep structures of the brain

What is the main risk factor for small vessel strokes?

• hypertension

What treatment is given to small and large vessel occlusive strokes?

• thrombolysis

• drug which dissolves blood clots

What treatment can be given to large vessel strokes?

• thrombectomy

• catheter physically pulls clot out of blood vessel

What is the difference between an ischaemic and haemorrhagic stroke?

• ischaemic = blocked blood vessel

• haemorrhagic = ruptured blood vessel that bleeds into the brain

List 4 types/causes of haemorrhagic stroke:

1. Aneurysm

2. Cerebral amyloid angiopathy

3. Arteriovenous malformations

4. Subarachnoid haemorrhage

How do aneurysms occur and cause haemorrhagic stroke?

• hypertension weakens lining of arterioles leading to aneurysm formation

• charcot bouchard aneurysm

• ruptures of these occur in deep structures of the brain

How does cerebral amyloid angiopathy occur and cause intracerebral haemorrhagic stroke?

• deposition of beta amyloid in small and medium sized cerebral arteries → causes vessel walls to become fragile and break easily → causes bleeding and stroke

Where about does haemorrhages occur (due to amyloid angiopathy) in the brain?

• on the border between grey and white matter

What are arteriovenous malformations and how do they cause stroke?

• they are abnormal tangles of blood vessels where there are direct connections between arteries and veins

• blood delivered at high pressure means the vessels are prone to rupture

What is a subarachnoid haemorrhage?

• bleeding that occurs into subarachnoid space (space between arachnoid membrane and pia mater)

• normally a berry aneurysm ruptures either spontaneously or due to trauma

Where do berry aneurysms often arise?

• sites of arterial bifurcation

Name the 2 types of aneurysm

1. fusiform

2. berry (saccular)

What is a fusiform aneurysm?

• entire vessel circumference dilates

What is a saccular (berry) aneurysm?

• one wall balloons

• most common cerebral aneurysm

In what two ways can you diagnose a brain aneurysm?

1. CT scan - star shaped pattern

2. Angiography

List 2 treatments for brain aneurysms

1. Surgical clipping - metal clip placed across aneurysm

2. Endovascular coiling - coils inserted via catheter to block the aneurysm

List 5 long term management ideas for patients post-aneurysm

1. blood pressure control

2. smoking cessation

3. reduce alcohol intake

4. rehabilitation

5. monitor for complications

What is a cavernous sinus thrombosis?

• a rare life threatening blood clot that forms in the cavernous sinuses

What is a usual cause of a cavernous sinus thrombosis?

usually bacterial infection spreading from the danger triangle of the face

How can infection spread intra-cranially within sinuses?

• ophthalmic and facial veins are valveless

What 5 cranial nerves can be compressed due to cavernous sinus thrombosis?

CN III - oculomotor

CN IV - trochlear

CN VI - abducens

CN VI and V2 - trigeminal branches ophthalmic and maxillary

When these cranial nerves are compressed what conditions can occur?

1. ophthalmoplegia

2. facial and eye pain

List 3 treatments for cavernous sinus thrombosis:

1. high dose IV antibiotics

2. anticoagulation

3. surgery to remove clot if severe

Define Hydrocephalus

• a condition where there is an excess accumulation of CSF within the ventricular system

What are three results of untreated hydrocephalus?

1. Raised intracranial pressure

2. Brain compression

3. Damage to brain tissue

What are the two types of hydrocephalus?

1. communicating hydrocephalus

2. non communication hydrocephalus

What is communicating hydrocephalus?

• CSF flows normally through ventricles but there is reduced absorption and excess CSF production

What is non-communicating hydrocephalus?

• obstruction prevents CSF flow between ventricles

What is the most common site of blockage for non-communicating hydrocephalus?

• the cerebral aqueduct

What are 2 causes of hydrocephalus:

1. congenital

2. acquired

List 4 clinical features of hydrocephalus in infants:

1. Enlarged head circumference

2. bulging fontanelle (as it remains open in infants)

3. feeding problems

4. downward eye gaze

List 4 clinical features of hydrocephalus in adults and older children:

1. morning headaches

2. balance problems

3. memory loss

4. cognitive decline

List 3 treatments of hydrocephalus:

1. Treat obstruction via tumour removal

2. Ventriculoperitoneal (VP) shunt

3. Endoscopic Third Ventriculostomy

What occurs during a VP shunt procedure?

• a one way valve is surgically placed into the ventricle and this is attached to a thin tube that drains excess CSF from the brain to another part of the body

List 2 places where excess CSF is shunted to and then reabsorbed:

1. Peritoneal cavity

2. right atrium

What occurs during an ETV?

• an opening is created in the floor of the third ventricle

• this allows CSf to bypass obstruction and enter the subarachnoid space directly