Increased blood flow in the middle cerebral artery. What's going on?

The increase in blood flow velocity in the middle cerebral artery is seen in two aspects. The first aspect is narrowing of the blood vessel. After narrowing, the lumen of the blood vessel becomes smaller, causing the speed of blood flow to increase. The second aspect is vasospasm. Recently, the patient has shown vasospasm for some reason. Doppler examination will show that the blood flow velocity in the middle cerebral artery is increased. The most authoritative examination is CTA or MRA to determine whether there is stenosis in the local blood vessels. If there is no stenosis, it is ruled out that the blood flow speed caused by stenosis is increased. Basically, it can be diagnosed as vasospasm. Moreover, the blood flow speed caused by vasospasm is faster and faster. After a period of time, the blood flow speed can be seen slowing down.