6.2.2 Acute headache attributed to non-traumatic subarachnoid haemorrhage (SAH)

Identification: Female patient, 52 years old, hypertensive, smoker (30 pack-years), with no previous neurological history. Current Illness History: Sudden onset of intense occipital headache (10/10) 3 hours ago, described as "a blow to the back of the head." Characteristics: Maximum intensity reached within seconds ("thunderclap headache") Progressive neck stiffness Marked photophobia and phonophobia Initial syncope episode (≈1 minute) No history of head trauma or prior vigorous physical activity Neurological Examination: General state: GCS 14 (E4V4M6), agitated Meningeal signs: Marked neck stiffness (+ Brudzinski and Kernig) Diffuse cutaneous hyperesthesia Focal signs: Absent (NIHSS = 0) BP: 180/110 mmHg Fundoscopy: Absence of subhyaloid hemorrhage (Fisher grade I) Complementary Exams: Urgent non-contrast cranial CT: Blood in basal cisterns (Fisher score 3) Thickening of bilateral Sylvian fissures No associated intraparenchymal hematoma CT Angiography: Saccular aneurysm (5.2 mm) in the anterior communicating artery Diffuse arterial vasospasm (Lindegaard ratio = 4) Lumbar puncture (after initial negative CT): Xanthochromic fluid 12,000 red blood cells/mm³ (difference <10% between 1st and 4th tubes) Bilirubin detected on spectrophotometry