Stuttering is not caused by a lack of blood flow. It is much more complicated than that. There are structural differences in the white tissue of the left and right motor cortex as well as functional differences in the conduction of impulses through neurotransmitters. Scientist call this phenomenon a “Hyperactive Action Inhibition Loop”. Very simply put: the brain receives a “stop” signal when there should be a “go” signal and the speech flow is interrupted.