Hi
So the branch vein is definitely not SCA artery(superior cerebellar). It's a branch of the major cerebral veins if you look up the diagram of venous sinuses of the brain. So the one mentioned is passing close to the trigeminal nerve.
Next Steps
So with a background of hemifacial spasm as mentioned in the history, this vein shouldn't really be a problem. If you are still concerned about the line mentioned in the MRI, get the films/CD and meet your nearest neurologist or radiologist for better understanding.
Health Tips
You can just be aware that if at all this is a problem, it will lead to more of symptoms of pain. There are medications to treat both this pain and the spasm.