The goal of this randomized controlled trial is to evaluate the benefits and safety of controlled hypotension in Chinese patients with unruptured intracranial aneurysms(UIA).

The main questions it aims to answer are:

• To provide high-level evidence of the benefits and safety of controlled hypotension in patients with UIA.
• To provide evidence-based medical evidence for blood pressure control of patients with UIA in neurosurgery, and promote the progress of accurate individual management of patients. In this study, the main intervention is enhanced blood pressure lowering in patients with UIA.

All Patients will be randomly assigned to either the standard blood pressure lowering (SBPL) group or the enhanced blood pressure lowering (EBPL) group.

Inclusion criteria

1. Age 18-75.

2. Chinese ethnicity.

3. Unruptured saccular intracranial aneurysm (UIA) identified by computational tomography angiography, magnetic resonance angiography or digital subtraction angiography.

   1. Maximal size of UIA at largest dimension < 7 mm
   2. The morphology of UIA is regular (no bleb(s) or secondary aneurysm(s) protruding from the UIA fundus or bi-/ multi-lobular UIA fundus)
   3. UIA receiving conservative treatment

4. History of primary hypertension (as diagnosed per standard of care)

5. Systolic blood pressure (SBP) on 2 consecutive visits:

   SBP: 130-180 mmHg on 0 or 1 antihypertensive medication. SBP: 130-170 mmHg on up to 2 antihypertensive medications. SBP: 130-160 mmHg on up to 3 antihypertensive medications. SBP: 130-150 mmHg on up to 4 antihypertensive medications

6. Good medication adherence (Morisky Medication Adherence Scale ≥6)

7. Obtain informed consent from patient or legal representative

Exclusion criteria:

1. Patients with neurological symptom related to UIA, such as sentinel headache, oculomotor paralysis and so on.
2. Patients with additional active intracranial disease including vasculopathy, arteriovenous malformation/fistula, cancer, traumatic brain injury etc.
3. Patients with fusiform, dissecting, blister, traumatic, mycotic/ bacterial, myxomatous, and tumor-associated UIAs are excluded.
4. Patients with history of polycystic kidney disease, rheumatic disease or autoimmune disease.
5. Patients with family history of intracranial aneurysm (defined when two direct relatives of patients within three generations have intracranial aneurysms or aneurysmal subarachnoid hemorrhage).
6. Patients with known secondary cause of hypertension.
7. Patients with myocardial infarction, ischemic stroke, symptomatic heart failure during the past 3 months.
8. Patients with a medical condition likely to limit survival to less than 2 years.
9. Patients during pregnancy and perinatal period.
10. Any concurrent serious illness that would interfere with the outcome assessments including hepatic, renal, gastroenterological, respiratory, cardiovascular, endocrinologic, immunologic, and hematologic disease.
11. Inability or unwillingness of patient or legal representative to give written informed consent.
12. Participation in a concurrent interventional medical investigation or clinical trial.