Non-traumatic SAH, linked in 85% of cases to the rupture of an intracranial aneurysm, is a serious stroke affecting young people. Half of all survivors suffer cognitive impairment. The presentation is that of a sudden-onset, isolated headache. This population is exposed to headache during hospitalization, which lasts an average of 13 days. This length of hospitalization is due to the fact that these patients must be monitored during the potential vasospasm period that occurs between days 4 and 14 after SAH. The pain associated with SAH is a source of discomfort and increased morphine consumption during the ICU stay, particularly during the first 10 days. Current recommendations call for conventional pain management with a combination of tier 1, 2 and/or 3 analgesics. For headache control, opioids are widely prescribed, sometimes in high doses, with adverse effects, despite efforts to reduce their use. Maximum headache pain scores remain high, indicating inadequate pain management. This highlights the urgent need to study alternative opioid-sparing and analgesia strategies for patients with SAH.

Sphenopalatine block is already used for certain types of facial and cranial pain, and could help save morphine consumption during hospitalization. The sphenopalatine ganglion is a crossroads for parasympathetic, sympathetic and sensory pathways. Recently studied in post-puncture dural breaches with promising results, sphenopalatine ganglion block (SPGN) may appear as an interesting alternative therapy in the treatment of SAH headaches. Other advantages of this block are its simplicity, efficacy and the absence of any noticeable adverse effects at the time it is performed. What's more, it is already used routinely in our department, with rapid and effective action. The hypothesis of the trial would be to reduce morphine consumption by at least 50% for patients benefiting from BGSP, for better neurological monitoring and optimal overall pain management in SAH.

Inclusion Criteria:

• ≥ 18 years
• Non-traumatic SAH with or without aneurysm on brain imaging
• WFNS score 1 and 2
• Patient awake and extubated after radiological procedure
• Patient in pain (EN > 3/10) despite usual level 1 analgesics (Paracetamol + Acupan)
• Affiliated with or benefiting from a social security scheme

Exclusion Criteria:

• Contraindication to sphenopalatine ganglion block (deviated nasal septum, repeated epistaxis, allergy to Lidocaine)
• Patient unable to assess pain by EN
• Persons covered by Articles L1121-5 to L1121-8 of the CSP and Articles 31 to 35 of Regulation 536/2014.
• Participation in other interventional research
• Patient's refusal to participate
• Arteriography more than 48 hours old
• Inaugural headache lasting more than 48 hours
• Presence of an unsecured vascular malformation at high risk of rupture