Fluency refers to the smoothness with which sounds and syllables, as well as words and phrases, are joined together while speaking. Fluency disorders are conditions characterized by the involuntary disruption of a person’s flow of speech beyond what is considered normal. While each of the fluency disorders has its own causes, symptoms, and effects, there are several main categories. The types of fluency disorders include stuttering and neurogenic disfluency, as well as mixed fluency failures and psychogenic disfluency.
Stuttering is the most common of the fluency disorders, characterized by a high frequency or prolonged duration of stoppages in the flow of speech. Stuttering is often confused with the normal developmental disfluency that a child may have as he learns and perfects his speech skills. The difference lies in that stuttering disorders occur alongside physical behaviors. These physical behaviors are called physical concomitants, including eye blinks, head nods, or total body gyrations.
Neurogenic disfluency is a set of fluency disorders that are caused by a neurological issue. These are identified in patients who have had no prior fluency problems, but who have undergone an event that directly led to the fluency issues. For example, a patient who has survived a stroke may have lost blood flow to the area of the brain that affects speech. As a result, he or she may have trouble choosing or forming words. The difference between neurogenic disfluency and other disorders is that this is not an issue of fluency at all, but a matter of the inability to control the muscles needed to speak properly.
Psychogenic disfluency is a disfluency that was triggered by a sudden identifiable emotional crisis. There are three categories of psychogenic disfluency: emotionally based disfluencies, manipulative disfluencies, and malingering disfluencies. For example, those who stutter when afraid are suffering from psychogenic disfluency. Treatment for this would be psychological in nature, helping the patient to overcome his fears and control his reactions during stressful situations.
There are also mixed fluency failures. These fluency disorders can come from any number of causes combined. For example, a child may be a developmental stutterer. Although he may grow out of it, as an adult, he may also revert to stuttering in stressful situations. He may have undergone developmental speech therapy as child and later psychotherapy to control his fear in stressful situations.