There is definately such a thing as a brain embolism. It can be quite dangerous and even deadly. It is caused from a blood clot that travels to the brain. The result is either a ischemic stroke which is a permanent, more serious type of stroke, or a transient ischemic stroke which is not usually as concerning, though still very serious.
When a person has a serious stroke, they can be left paralyzed, unable to move certain body parts, unable to talk, or even dead. Those who have the transient type may regain any function or functions they lost during the stroke in a relatively short time without much need for therapy. Those who suffer the more severe type may not even recover their functions through therapy and some may on partially recover. Embolisms in the brain are one of the main reasons for strokes. Any suspicion that this has occured is cause for immediate medical attention.