Having stuttered for over 30 years and as you stated, fully recovered less than 2 years ago, I think I have some unique anecdotes. My untreated respiratory issues during childhood at least significantly contributed to my developmental stuttering. During my recovery, there were times when my facial muscles twitched and my tongue pulled hard in various directions. Sometimes I'd feel pleasurable tingling sensations in my head. I definitely had neurological dysfunction, but that's because my orofacial skills developed dysfunctionally. I suspect there are others that stutter because of issues similar to mine and others that stutter due to completely different issues.