Stuttering

===Classification===
Developmental stuttering is stuttering that originates when a child is learning to speak and may persist as the child matures into adulthood. Stuttering that persists after the age of seven is classified as persistent stuttering.<ref name="Sander and Osborne" />

Neurogenic stuttering (stuttering that occurs secondary to brain damage, such as after a stroke) and psychogenic stuttering (stuttering related to a psychological condition) are less common and classified separately from developmental.<ref name="Sander and Osborne" />

====Developmental====
Stuttering usually begins in early childhood.<ref name="gordon">{{cite journal |author=Gordon, N. |title=Stuttering: incidence and causes |journal=Developmental Medicine & Child Neurology |volume=44 |issue=4 |pages=278–81 |year=2002 |pmid=11995897 |doi = 10.1111/j.1469-8749.2002.tb00806.x }}</ref><ref name="craig2005">{{cite journal|author1= Craig, A.|author2= Tran, Y.|title=The epidemiology of stuttering: The need for reliable estimates of prevalence and anxiety levels over the lifespan|journal= Advances in Speech Language Pathology|volume=7 |issue=1 |pages=41–46 |year=2005 |doi= 10.1080/14417040500055060|s2cid= 71565512}}</ref> The mean onset of stuttering is 30 months.<ref name="fn 30"/> With young stutterers, disfluency may be episodic, and periods of stuttering are followed by periods of relatively decreased disfluency.<ref>{{harvnb|Ward|2006|pp=114–5}}</ref>

With time a young person who stutters might transition from easy, relaxed repetition to more tense and effortful stuttering, including blocks and prolongations. Some propose that parental reactions may affect this development. With time, secondary stuttering, including escape behaviours such as eye blinking and lip movements, may be used, as well as fear and avoidance of sounds, words, people, or speaking situations. Eventually, some become fully aware of their disorder and begin to identify themselves as stutterers. Depending on the situation, this may come with deeper frustration, embarrassment and shame.<ref>{{harvnb|Ward|2006|pp= 115–116}}</ref> 

Other patterns of stuttering development have been described, including sudden onset, with the child being unable to speak, despite attempts to do so. The child usually is unable to utter the first sound of a sentence, and shows high levels of awareness and frustration. Another variety also begins suddenly with frequent word and phrase repetition, and does not include the development of secondary stuttering behaviours.

=====Neurogenic stuttering=====
Some stuttering is also believed to be caused by neurophysiology. Neurogenic stuttering typically appears following some sort of injury or disease to the central nervous system. Injuries to the brain and spinal cord, including cortex, subcortex, cerebellum, and even the neural pathway regions.<ref name="Carlson, N. 2013 pp. 497-500"/>

====Acquired stuttering====
In some cases, stuttering may be acquired in adulthood as the result of a neurological event such as a head injury, tumour, stroke, or drug use. This stuttering has different characteristics from its developmental equivalent: it tends to be limited to part-word or sound repetitions, and is associated with a relative lack of anxiety and secondary stuttering behaviors. Techniques such as altered auditory feedback are not effective with the acquired type.<ref name="gordon"/><ref name="craig2005"/><ref>{{harvnb|Ward|2006|pp= 4, 332–335}}</ref>

Additionally, psychogenic stuttering may also arise after a traumatic experience such as a death, the breakup of a relationship or as the psychological reaction to physical trauma. Its symptoms tend to be homogeneous: the stuttering is of sudden onset and associated with a significant event, it is constant and uninfluenced by different speaking situations, and there is little awareness or concern shown by the speaker.<ref>{{harvnb|Ward|2006|pp= 4, 332, 335–337}}</ref>
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