Subarachnoid Haemorrhage

Question 1

What is a subarachnoid haemorrhage (SAH)?

Answer 1

A subarachnoid haemorrhage (SAH) is an intracranial haemorrhage that is defined as the presence of blood within the subarachnoid space, i.e. deep to the subarachnoid layer of the meninges (the anatomical space between the arachnoid mater and pia mater).

Question 2

Briefly describe the anatomy of the meninges

Answer 2

Question 3

What are the risk factors for SAH?

Answer 3

• Family history
• Female gender
• African descent
• Smoking
• Hypertension
• Excessive alcohol
• Cocaine use

Question 4

Who is commonly affected by SAH?

Answer 4

They typically occur in patients around 60 yrs old and account for 3% of all strokes.

Subarachnoid haemorrhage is more common in black and female patients.

Question 5

What conditions are associated wtih SAH?

Answer 5

It is particularly associated with:

• Cocaine use
• Sickle cell anaemia
• Connective tissue disorders (such as Marfan syndrome or Ehlers-Danlos)
• Neurofibromatosis
• Autosomal dominant polycystic kidney disease

Question 6

How can SAH be classified?

Answer 6

SAH can be classified into either aneurysmal or non-aneurysmal causes:

• Aneurysmal disease (85%) is associated with ADPKD, fibromuscular dysplasia, connective tissue disorders, atherosclerosis and hypertension
• Non-aneurysmal causes for SAH include trauma, arteriovenous malformations, coagulopathies and tumour-related

Question 7

What is the most common cause of SAH?

Answer 7

The most common cause of SAH is head injury and this is called traumatic SAH.

Question 8

What are berry aneurysms?

Answer 8

Berry aneurysms are ‘berry-shaped’ true aneurysms that occur at the bifurcation of arteries.

They are typically saccular aneurysms that occur mostly at either the circle of Willis and the bifurcation of the middle cerebral artery.

Unruptured aneurysms occur in around 3% of the adult population; those that present ruptured will be at the age 40-60yrs and can cause either a subarachnoid haemorrhage, cerebral haematoma, or intraventricular haemorrhage.

Question 9

How do berry aneurysms lead to SAH?

Answer 9

Intracranial aneurysm= saccular ‘berry’ aneurysms.

This accounts for around 85% of SAH cases.

Aneurysmal SAH causes substanital morbidity and mortality. When a cerebral aneurysm ruptures, blood flows into the subarachnoid space, sometims seeping into the brain parenchyma and/ or the ventricles. The sudden increase in intracranial pressure, as well as the destructive and toxic effects of blood on brain parenchyma and cerebral vessles, accounts for most complications.

Question 10

What conditions have an increased risk of berry aneurysms?

Answer 10

Conditions associated with berry aneurysms include adult polycystic kidney disease, Ehlers-Danlos syndrome and coarctation of the aorta.

Question 11

What are the clinical features of SAH?

Answer 11

SAH will classically presents with a severe headache, sudden onset (within seconds to minutes), typically in the occipital region (often termed “thunderclap” headaches).

Other features include nausea and vomiting, reduced consciousness, collapse, or seizures, or evidence of meningism (including photophobia, stiff neck, pain on neck flexion, or positive Kernig’s sign).

Question 12

How will SAH show on a neurological examination?

Answer 12

Examination may reveal focal neurology or evidence of meningism, however may be otherwise unremarkable.

Question 13

What investigations should be ordered for SAH?

Answer 13

• Non-contrast CT head
• FBC
• Serum electrolytes
• Clotting profile
• Troponin I
• Serum glucose
• ECG
• Lumbar puncture
• Angiography (CT or MRI)

Question 14

What is the gold standard test for SAH?

Answer 14

CT head is the first line investigation. Immediate CT head is required.

Question 15

How will SAH present on a CT head?

Answer 15

Blood will cause hyperattenuation in the subarachnoid space therefore hyperdense areas in the subarachnoid space/basal cisterns.

Question 16

When should a lumbar puncture be performed for diagnosing SAH?

Answer 16

Perform an LP if CT head is negative (2% of patients) or inconclusive but you have a high clinical suspicion of SAH. However, wait for at least 12 hours to pass from the onset of symptoms before performing an LP.

Question 17

What may a lumbar puncture show in SAH?

Answer 17

CSF can be tested for signs of subarachnoid haemorrhage:

• Red cell count will be raised
  
  • If the cell count is decreasing in number over the samples, this could be due to a traumatic lumbar puncture
• Xanthochromia (the yellow colour of CSF caused by bilirubin)

Question 18

What is the role of angiography (CT or MRI) in diagnosing SAH?

Answer 18

Request angiography (CT or MRI) in patients with confirmed SAH to identify the causal pathology, define anatomy, and plan the best option to secure the aneurysm related to the haemorrhage.

Question 19

Briefly describe the immediate treatment of SAH

Answer 19

Patients should be managed by a specialist neurosurgical unit. Patients with reduced consciousness may require intubation and ventilation.

Observe the patient continuously using GCS scoring.

Give nimodipine (orally, or by nasogastric tube if the patient is unable to swallow) as soon as SAH is confirmed to prevent delayed cerebral ischaemia and improve outcomes such as survival and being independent in activities of daily living.

Question 20

What is the role of nimodipine in treating SAH?

Answer 20

Nimodipine is a calcium channel blocker that is used to prevent vasospasm. Vasospasm is a common complication that can result in brain ischaemia following a subarachnoid haemorrhage.

Question 21

What is the role of surgery in treating SAH?

Answer 21

Surgical intervention may be used to treat aneurysms. The aim is to repair the vessel and prevent re-bleeding. This can done by coiling, which involves inserting a catheter into the arterial system (taking an “endovascular approach”), placing platinum coils into the aneurysm and sealing it off from the artery. An alternative is clipping, which involves cranial surgery and putting a clip on the aneurysm to seal it.

Question 22

What are the clinical features of hydrocephalus in SAH?

How is is treated?

Answer 22

Gradually worsening level of arousal with relative preservation of deliberate motor responses, severe headache, vomiting and agitation.

Refer urgently to a neurosurgeon if there are signs/symptoms of acute hydrocephalus. Lumbar puncture or insertion of a shunt may be required to treat hydrocephalus.

Question 23

What are the complciations of SAH?

Answer 23

• Neuropsychiatric problems
  
  • Over 50% of survivors report cognitive impairment (e.g., mood and memory problems), resulting in a negative impact on functional status, emotional health and quality of life
• Chronic hydrocephalus

Question 24

What differentials should be considered for SAH?

Answer 24

• Arterial dissection
• Cerebral and cervical arteriovenous malformation (AVM)
• Dural arteriovenous malformations (AVF)
• Vasculitis

Question 25

What is shown in the image?

Answer 25

SAH

Question 26

What is shown in the image?

Answer 26

SAH

Question 27

What is shown in the image?

Answer 27

SAH

Question 28

Review the various intracranial bleeds

Answer 28

(A) axial

(B) coronal views

EDH = epidural haematoma

SDH = subdural haematoma

SAH = subarachnoid haemorrhage

IPH = intraparenchymal haemorrhage