Noninvasive CA Monitoring Validation and Autonomic Modulation in Aneurysmal Subarachnoid Hemorrhage

Inclusion Criteria (Component 1 - All Enrolled Participants): * Age 18 years or older * Primary diagnosis of aneurysmal subarachnoid hemorrhage (aSAH), confirmed by imaging * Admitted to the NSICU at Clements University Hospital, UT Southwestern Medical Center * Informed consent obtained from subject or legally authorized representative (as defined under Texas Health and Safety Code Section 166.039) * Brain4Care extensometry sensor placeable at an appropriate cranial site not occluded by surgical dressings or EVD hardware * Open EVD with active continuous ICP monitoring (required for EVD clamping sub-protocol only; not required for Aims 2 or 3) Exclusion Criteria (Component 1): * Age younger than 18 years * Prisoner status * Primary NSICU admission diagnosis other than aSAH * Active declination by subject or legally authorized representative * Brain4Care sensor not placeable at any accessible cranial site * Active clinical deterioration making research monitoring impractical at time of approach * Physician-of-record declining research enrollment for clinical reasons * Inability to provide informed consent in English * Known pregnancy at time of enrollment Additional Inclusion Criteria for Component 2 (Aim 3 - CSB and taVNS): * At least one successful EVD clamping session completed * PI documentation of Component 2 operational readiness, co-signed by qualified co-investigator or Department Director * INR 1.5 or less and platelet count 50,000/uL or greater within 24 hours …