10.4 Subarachnoid Haemorrage

Question 1

Stroke
Other name
Types

Answer 1

• Also called a cerebrovascular accident (CVA)

Types of stroke:
- Ischemic stroke - occlusion of blood flow to brain
• Infarction (occlusion or embolization).
- Hemorrhagic stroke - spontaneous intracranial haemorrhage
• Hypertensive intracerebral hemorrhage
• Subarachnoid hemorrhage

Question 2

Define Subarachnoid haemorrhage

Answer 2

• bleeding into subarachnoid space (true space between pia mater and arachnoid mater)
• large blood vessels of brain lie here

Question 3

Causes of Subarachnoid haemorrhage

Answer 3

• Trauma (most common 80%) - injury to small cortical blood vessel
• Spontaneous
  • Aneurysmal rupture (most common)
  • AVM
  • Vasculitis
  • Neoplasm
  • Anticoagulant therapy
  • Clotting abnormalities (genetic and acquired)
  • Hypertension
  • Unknown (peri-mesencephalic SAH)

Question 4

Biology of cerebral aneurysms

Answer 4

• always acquired
• aneurysms develop over time at branch points if high intravascular turbulence and abnormal vessel wall stresses
• arise in areas with complex vascular geometry (bifurcation and curves)
• area of weakend wall + stresses
• environmental factors also play a role (smoking)
• cause inflam response in vessel wall

Question 5

Risk Factors associated with formation of cerebral aneurysms

Answer 5

• Smoking
• Hypertension (most significant)
• Family history of brain aneurysms
• Age over 40
• Female sex
• Connective tissue disorders [Ehlers-Danlos Syndrome, Polycystic Kidney Disease, Marfan Syndrome, Fibromuscular Dysplasia (FMD)]
• Presence of an AVM (atrial venous malformation)

Question 6

Risk factors associated with aneurysm rupture

Answer 6

• Hypertension
• Smoking
• Race (Finnish, Japanese, Hispanic)
• Aneurysm size (more than 7mm)
• Aneurysm location
• Previous aneurysm rupture
• Alcohol abuse

Question 7

Aneurysm location

Answer 7

• occur at branching points of large blood vessels around circle of Willis
• 90% occur in the anterior circulation
• Anterior communicating artery 30 – 35%
• Internal carotid artery and associated branches 30%
• Middle cerebral artery 22%
• Posterior circulation 10% - basilar apex, superior cerebellar artery, posterior inferior cerebellar artery

Question 8

Clinical presentations of subarachnoid bleed

Answer 8

• Mostly Asym

Thunderclap headache
- “worst headache of my life”, sudden onset, maximal intensity at onset

Associated symptoms
- Nausea and vomiting
- Photophobia
- Neck stiffness
- Loss of consciousness
- Focal neurological deficits
- Seizure

Severe cases
- Decreased level of consciousness
- Coma
- Sudden death

Question 9

What is the WFNS score used for?

Answer 9

To predict outcome of pt after subarachnoid haemorrhage
Uses:
- Glasgow coma score
- presence of motor deficit

Question 10

Modified Fisher grading system

Answer 10

• radiological grading
• determine risk for vasospasm & delayed neurological ischeamic deficit

Look at:
- thickness of subarachnoid haemorrhage
- absence or presence of intraventricular haemorrhage

Question 11

Complications of subarachnoid haemorrhage

Answer 11

Aneurysm re-bleed
- Risk of aneurysm re-rupture
• 8 – 23% in first 72 hours
• Hypertension
• Initiation of CSF drainage
• Thick subarachnoid blood on CT
• WFNS score
• Aneurysm size
- Mortality rate 60%
- Important to prevent re-rupture

Vasospasm and Delayed ischeamic neurological deficit
- Narrowing of angiograpically visible arteries
• Seen in 70% of patients after aneurysmal SAH
• Usually starts 3-4 days after aneurysm rupture
• Peaks at 7 to 10 days
• Resolves by 14 to 21 days
- Delayed ischemic neurological deficit (DIND)
• Clinical syndrome of focal neurologic deficits
• Typically 4 to 14 days after aneurysm rupture
• Develops in one third of patients after aneurysm rupture
• Variety of vascular and neural changes take place after subarachnoid haemorrhage
• Major cause of death and disability after subarachnoid hemorrhage

Hydrocephalus
- Incidence between 15 – 85%
- Acute hydrocephalus
• Blood in the ventricular system or blood in the subarachnoid space
• Obstructs normal CSF circulation
- Chronic hydrocephalus develops in approximately 1/3 of patients
• Fibrosis of subarachnoid space causes communicating hydrocephalus
• Decline in neurological condition
• VP shunt

Medical
- Electrolyte disturbance
• Hyponatremia / hypernatremia
• Hypokalemia
- Cardiac arrhythmia
- Deep venous thrombosis
- Hypothalamic dysfunction