Subarachnoid haemorrhage

Pathophysiology

  • Most commonly due to trauma.
  • Spontaneous SAH are mostly caused by a rupture of intracranial aneurysm (75%). Can also be caused by AV malformations, vasculitis, coagulopathy.
  • Aneurysms most commonly at junction between:
    • posterior communicating and ICA
    • anterior communicating and ACA
    • bifurcation of MCA
  • Aneurysms classically associated with:
    • Polycystic kidney disease
    • Ehlers-Danlos
    • Aortic coarctation

Classic presenting complaint

  • 55yo, female, Japanese/Finnish/Black descent
  • Sudden onset “thunderclap” headache classically occipital
  • Vomiting + photophobic + syncope
  • PMH: poorly controlled HTN, smoker, cocaine use

On examination

  • Reduced GCS – may not recover
  • Meningism
    • Nuchal rigidity
    • Kernig’s sign (flex hip with knee bent, then extend knee – positive if pain in hamstring)
    • Photophobia
  • Ocular haemorrhage (? due to raised ICP)
    • subhyaloid haemorrhage
    • intra-retinal haemorrhage
    • vitreous haemorrhage (=<25% of aneurysmal SAH)
  • Unequal pupils – aneurysmal compression of CN III

Clinical approach & differential

  • Benign thunderclap headaches (crash migraines) – no blood on CT/LP
  • Reversible cerebral vasoconstrictive syndrome (RCVS) – vasculitis associated with previous use of vasoconstrictive agents
  • Meningitis
  • Migraine
  • ICH
  • Cortical vein thrombosis

Investigations

  1. Urgent non-contrast CT head
  2. If CT normal, LP in those with strong history
    • 3 bottles + glucose bottle
    • Xanthochromia
    • microscopy, C&S, protein

Classic findings

Taken from Radiopaedia

Traumatic SAH – taken from Radiopaedia

CT sensitivity within 48h: 90-95%

High attenuation (blood) in the subarachnoid space, most obviously around the circle of Willis, basal cisterns or in the Sylvian fissure.

Prognosis

If due to aneurysm:

  • 10% die before reaching hospital
  • 10% mortality within first few days
  • 45% mortality overall

If survives and not treated, risk of re-bleed within 2 weeks: 20%

Treatments

Plan

  • ABC
  • Elevate head of bed
  • Consider mannitol +/- furosemide
  • Treat seizures if required
  • Nimodipine 4hourly or IVI
  • Urgent neurosurgery referral
  • Urgent ICU bed
  • 1 hourly neuro-obs
  • Aim systolic BP 120-150
  • Fluids (beware cerebral salt wasting/SIADH – do not fluid restrict)
  • Stool softeners
  • NBM

Neurosurgical/vascular options:

  • CTA or angiography
  • Endovascular coiling
  • Intraventricular catheter (venticulostomy) if hydrocephulus develops