Subarachnoid Haemorrhage Flashcards
What is a subarachnoid haemorrhage?
It is an intracranial haemorrhage within the subarachnoid space, which is located between the pia mater and the arachnoid membrane
What are the seven causes of subarachnoid haemorrhage?
Berry Aneurysm Rupture
Arteriovenous Malformation
Cerebral Trauma
Pituitary Apoplexy
Arterial Dissection
Mycotic Aneurysms
Perimesencephalic
What is the most common cause of subarachnoid haemorrhages?
Berry aneurysm rupture
What are berry aneurysms?
They are aneurysms located within the Circle of Willis
In which three junctions do berry aneurysms tend to form?
Between the posterior communicating artery and the internal carotid artery
Between the anterior communicating artery and the anterior cerebral artery
At the bifurcation of the middle cerebral artery
What four conditions are associated with berry aneurysms?
Autosomal Dominant Adult Polycystic Kidney Disease
Ehler’s Danlos Syndrome
Aorta Coarctation
Hypertension
What are the eight risk factors of subarachnoid haemorrhage?
Female Gender
Older Age 45 – 70
Black Ethnicity
Family History
Hypertension
Sickle Cell Anaemia
Smoking
Cocaine Use
What are the nine clinical features of subarachnoid haemorrhage?
Thunderclap Headache
Nausea & Vomiting
Neck Stiffness
Photophobia
Diplopia
Slurred Speech
Unilateral Weakness
Loss of Consciousness
Seizures
What is the most common clinical feature associated with subarachnoid haemorrhages?
Thunderclap headache
What is thunderclap headache? How long does it take to reach maximum intensity?
It refers to a sudden onset, severe occipital headache
The headache reaches maximum intensity within one minute
What tends to onset thunderclap headaches?
Strenuous activity, such as physical exercise or sexual intercourse
What four investigations are used to diagnose subarachnoid haemorrhages?
Non-Contrast CT scans
Lumbar puncture
CT intracranial angiography
ECG Scan
What is the first line investigation used to diagnose subarachnoid haemorrhages?
Non-Contrast CT scan
What feature on CT scans indicates a diagnosis of subarachnoid haemorrhage?
Hyperdense material (blood) within the subarachnoid space
In most cases, this is apparent within the circle of Willis region, in which berry aneurysms occur - involving the basal cisterns, sulci and in severe cases the ventricular system
What is the most appropriate next step in cases where a CT scan is conducted within 6 hours of clinical features and results are normal, however clinical history is suggestive of subarachnoid haemorrhage?
Do not conduct a lumbar puncture
Consider an alternative diagnosis
What is the most appropriate next step in cases where a CT scan is conducted after 6 hours of clinical features and results are normal, however clinical history is suggestive of subarachnoid haemorrhage?
Lumber Puncture
What is a lumbar puncture?
It involves obtaining a sample of CSF by inserting of a needle into the subarachnoid space of the spinal cord, specifically between L3 and L4 vertebrae
What four lumbar puncture features indicate a diagnosis of subarachnoid haemorrhage?
Increased Red Cell Count
Increased Bilirubin Levels
Xanthochromia
Increased Opening Pressure
What is xanthochromia? What is the cause?
It is yellow CSF sample
This is due to bilirubin build up
What is a traumatic tap?
This is the introduction of blood into CSF samples due to the lumbar puncture procedure
What distinguishes true subarachnoid haemorrhage from a traumatic tap?
Xanthochromia
When should lumbar punctures be conducted when used to diagnose subarachnoid haemorrhage? Why?
12 hrs > headache onset
This allows time required for the RBCs to breakdown and produce xanthochromia
What is CT intracranial angiography?
It involves the conduction of a head CT scan, with an intravenous contrast, in order to highlight the cerebral arteries and investigate the formation of blood clots
When are CT intracranial angiography conducted in subarachnoid haemorrhage patients? Why?
This investigation is conducted once a diagnosis of subarachnoid haemorrhage has been confirmed
In order to identify a causative pathology, that may require urgent treatment
What is the feature of subarachnoid haemorrhage on ECG scans?
ST elevation
What are the two pathophsyiological causes of ST elevation in subarachnoid haemorrhage?
It is secondary to either autonomic neural stimulation from the hypothalamus
It is secondary to elevated levels of circulating catecholamines
What two supportive management options are used in subarachnoid haemorrhage patients?
Fluid management
Intubation and ventilation - in patients with a reduced consciousness
What two pharmacological management options are used in subarachnoid haemorrhage patients?
Nimodipine
Anticonvulsants
What is the mechanism of action of nimodipine?
It is a calcium channel inhibitor which targets cerebral vasculature
Why do we prescribe subarachnoid haemorrhage patients nimodipine?
To prevent vasospasm, which is a common complication following subarachnoid haemorrhage that can result in brain ischaemia
How long do we usually prescribe nimodipine to subarachnoid haemorrhage patients?
3 weeks
When are anticonvulsants used to treat subarachnoid haemorrhage patients?
In cases where seizure development occurs
What anticonvulsant is commonly prescribed?
Phenytoin
What four surgical procedures are used to treat subarachnoid haemorrhage?
Endovascular Coiling
Surgical Clipping
Lumbar Puncture
External Ventricular Drain
When is endovascualr coiling selected as the subarachnoid haemorrhage treatment?
When the underlying pathology is related to a berry aneurysm
What is endovascular coiling?
It involves the insertion of a catheter into the femoral artery, which is then guided to the cerebral arteries containing the aneurysm
Platinum coils are then passed through the catheter and into the aneurysm, resulting in separation of the aneurysm from the main artery, and therefore prevention of further rupture
When is surgical clipping selected as the subarachnoid haemorrhage treatment option?
When the underlying pathology is related to a berry aneurysm
What is surgical clipping?
It involves the conduction of a craniotomy and the placement of metal clip around the base of the aneurysm to separate the aneurysm from the main artery, preventing further rupture
How do we decide which procedure to conduct - endovascualr coiling or surgical clipping?
It is dependent on the location, shape and size of the aneurysm
What procedure is preferred - endovascualr coiling or surgical clipping? Why?
Endovascular coiling
A reduced risk of short term complications and shorter recovery times
How soon should intracranial aneurysms be treated? Why?
Within 24 hours
Due to the risk of re-bleeding
What are the three conservative measures that can be used to prevent aneurysm re-bleeding until surgical management is arranged?
Bed rest
Blood pressure control
Avoid straining
What is an external ventricular drain procedure?
It involves the insertion of a catheter into the frontal lobe of the brain where the lateral ventricles are situated, enabling drainage of CSF into an external collecting system
When is lumbar puncture and external ventricular drain procedures used to treat subarachnoid haemorrhages?
When hydrocephalus complications have developed
What six complications are associated with subarachnoid haemorrhage?
Aneurysm Re-Bleeding
Vasospasm
Hyponatraemia
Seizures
Hydrocephalus
Torsades de Pointes
What is the cause of hyponatraemia in subarachnoid haemorrhage patients?
SIADH
What are the four clincial features of SIADH?
Drowsiness
Nausea
Headache
Muscle Cramps
Which blood test is most important to conduct in order to monitor complications? Explain
U&Es
This is due to the fact that hyponatraemia is a common complication
How soon after subarachnoid haemorrhage does aneurysm re-bleeding usually occur?
Within 12 hours
How soon after subarachnoid haemorrhage does vasospasm usually occur?
7-12 days
What are the three predictive factors of subarachnoid haemorrhage?
Conscious Level on Admission
Age
Blood Volume Visible on CT Head
