Speech Defects (Aphasia, Dysphonia, and Stuttering)

Because speech is essential to human communication, anything that interferes with it can be isolating and emotionally distressing. Primary mutism, in which a person cannot speak due to absent vocal cords or another structural defect, is rare. More commonly, difficulty speaking is secondary to other conditions, including paralysis, deafness, retardation or other mental disorders, and larynx cancer. In certain cases, a person knows how to speak but has difficulty forming words.


Three often encountered disorders are: Aphasia (from the Greek, meaning "without speech"), in which brain damage impairs a person's ability to speak and/or understand spoken or written words. Sudden aphasia usually is due to a stroke or a head injury, whereas the likely cause of slowly developing aphasia is a brain tumor or progressive dementia.
next.............. 
http://www.healthlessonsonline.com/speech-defects/