"what do you think caused the disruption in the first place?" You're asking a million dollar question. By doing so, you are conceding that impaired cerebral blood flow may be causative of stuttering. However, there have been genetic studies indicating that oxygen homeostasis may be impaired in people who stutter. Moreover, reduced cerebral blood flow is not just in a small group of people who stutter like you tried to insinuate. In fact, that study showed a very strong association between reduced CBF in left brocas area in people who stutter compared to controls and the reduction was proportional to the severity. In addition, you're attempting to reduce stuttering to subjective and unreliable psychological aspects like social anxiety. That simply ignores the mountain of evidence of many objective things going on in stuttering that warrant further investigation. You are also trying to claim that social anxiety led to stuttering to begin with. That's not a claim that you can corroborate, nor is it a claim that the research supports.