By Kerri Turner There are a number of speech impediments. Stuttering, also known as stammering, is one. Lisping is another. Inability to speak at all is known as muteness. If the vocal muscles are damaged, paralyzed or weak, the cause may be in the nerves or the brain. This condition is called dysarthria. Stroke victims may have this condition as may those with Parkinson's disease or cerebral palsy. Surgical misadventure and injuries to the head...