Fast blood flow in the brain is mostly detected by ultrasound in the intracranial segment. For fast blood flow in the brain, oral medication can be considered to relieve the patient, clinically there are commonly used calcium antagonists, such as flunarizine hydrochloride, nimodipine, or intravenous vasodilatation with fasudil hydrochloride and niacin injection to relieve vasospasm. After vasospasm, blood flow will increase, and some patients with stenosis will also have increased blood flow speed. You can take oral medications to protect the intima, such as Rosuvastatin, Simvastatin, etc. You can also apply drugs to relieve the progress of atherosclerosis, such as vitamin E or niacin, etc. If the stenosis is obvious, you can consider giving stents or doing endothelial stripping surgery, etc.