(A&E) (Clinical Imaging)

Overview

• Bleeding into the subarachnoid space (between arachnoid and pia) and is an emergency
• Traumatic → Head Trauma
• Nontraumatic → Ruptured Intracranial Aneurysm (most commonly occurs in the circle of willis, ‘berry’ aneurysms), Arteriovenous Malformations, Anticoagulant Use
• Risk Factors → hypertension, smoking, FH, alcohol use, age >50 yrs old, FH of polycstic kidney disease (autosomal dominant)

Making Diagnosis

Clinical Features:

• Thunderclap Headache → severe, sudden-onset, occipital headache within 1-5 mins and lasts >1 hour
• Reduced level of consciousness
• Meningeal Signs → neck stiffness, photophobia, N&V, seizures, muscle aches

Investigations:

• Non-Contrast CT Head → order in all patients presenting with thunderclap headache. Diagnsotic test for SAH. Will see hyperdense areas in subarachnoid space.
  • Lumbar Puncture → 2nd line. If CT Head is negative (2% of patients) but high clinical suspicion of SAH. Wait 12 hours to pass from onset of symptoms to allow development of xanthochromia (presence of bilirubin in CSF due to RBC breakdown, leading to yellow discolouration).
• Computed Tomography Angiography (CTA) → requeset in patients with confirmed SAH, to identify cause/location and plan repair.
• ECG → arrhythmias, prolonged QT, ST segment or T-wave abnormalities