BLOCK-SAH - PPF-Block for Post-SAH Headache (BLOCK-SAH)

Inclusion Criteria: In order to be eligible to participate in this study, an individual must meet all of the following criteria: Provision of signed and dated informed consent form Stated willingness to comply with all study procedures and availability for the duration of the study Male or female, aged ≥18 and ≤ 85 years Admitted with a primary diagnosis of spontaneous, non-traumatic, subarachnoid hemorrhage within 48 hours of ictus hemorrhage Disease-specific inclusion criteria: Aneurysm identified as culprit of SAH modified Fisher grade 1-4 (on admission imaging) Hunt and Hess 1-3 or World Federation of Neurosurgeons grade 1-4 (on admission, included only if also fulfilling Glasgow Coma Scale verbal subscore≥4) minimum Glasgow Coma Scale verbal subscore of 4 (on screening) Able to verbalize pain scale scores according to 11-point numeric pain scale In order to be enrolled and undergo randomization in this study, an individual must meet all of the additional criteria: Stabilization period criteria: Between 4-48 hours from clipping or coiling procedure (whichever applicable) Successful treatment of culprit vascular lesion (i.e., ≥90% obliteration of aneurysm) Requiring a minimum of 15mg OME prn during the 24-hour period immediately prior to enrollment Exclusion Criteria: An individual who meets any of the following criteria will be excluded from participation in this study: Premorbid conditions: Pre-existing neurologic, psychiatric, or other condition that would confound neurologic assessment or would make difficult/impossible to accurately assess neurologic and/or functional outcome Prior use of opioid or barbiturate analgesics for at least two-thirds of the days in previous month, regardless of indication Diagnosis of substance use disorder in the previous year Infected or wounded skin, or a skin lesion at the site of puncture for PPF-injection Uncorrected coagulopathy platelet count < 50,000/μL, INR > 1.7 requiring use of systemic anticoagulation, ticagrelor or dual antiplatelet therapy SAH-specific: Head trauma as etiology of SAH Infection as cause for aneurysm or SAH (i.e., mycotic aneurysms) Inability to successfully treat culprit vascular lesion Diffuse vasospasm on initial diagnostic angiography (vasospasm defined as: moderate-to-severe arterial narrowing on digital subtraction angiography not attributable to atherosclerosis, catheter-induced spasm, or vessel hypoplasia, as determined by a neuroradiologist or neurointerventionalist) 118 Standard pain regimen conditions Elevation of hepatic enzymes prohibiting use of scheduled acetaminophen (i.e., AST or ALT > 3x upper limit level) Chronic liver condition with absolute contra-indication for acetaminophen (even at lower maximum daily doses) Participation in a concurrent investigational/interventional study (observational studies allowed) Known to be pregnant, or with a positive pregnancy test Allergy or intolerance to the medications used in the PPF-block (i.e., ropivacaine, dexamethasone) or standard pain regimen (acetaminophen)