The purpose of this paper is to give an overview of the knowledge currently available on dysarthria, and the characteristics, prevalence and effects of dysarthria in children with Cerebral Palsy. It will also examine the effects of speech therapy on children who have been diagnosed with both Cerebral Palsy and dysarthria. The term Cerebral Palsy has been used as an umbrella term for which a number of different definitions have been proposed over the years. The most recent consensus definition recognizes that Cerebral Palsy is characterized by movement and posture disturbance, is nonprogressive in nature, has its onset within the pre- or neonatal period, is caused by some type of damage to the central nervous system, and is often accompanied by co-occurring problems with sensation, perception, cognition, communication, and behavior (Rosenbaum et al., 2007). This paper will define Cerebral Palsy as a group of chronic, non-progressive, neurological disorders that occur in young children (Ingram, 1964). It is a lifelong disorder that permanently affects the development of both body movement and muscle coordination. This developmental disability is characterized by an inability to fully control motor function and abnormalities in the parts of the brain that control muscle movement. There are three main types of Cerebral Palsy, Spastic Cerebral Palsy, Atonic Cerebral Palsy, Athetoid Cerebral Palsy and Mixed Cerebral Palsy. The most common type of Cerebral Palsy is Spastic, in which a few muscles or the whole body may be affected. An individual with spastic Cerebral Palsy may have tight muscles and exaggerated reflexes or difficulty moving. Atonic Cerebral Palsy causes poor balance, poor depth perception, an unsteady walk, and poor coordination, and is characterized by a lack of muscle tone. Athetoid Cerebral Palsy is characterized by involuntary movements, causing individuals to appear as if they are squirming or constantly moving. Lastly, Mixed Cerebral Palsy occurs when an individual has a combination of spastic, atonic, athetoid Cerebral Palsy symptoms. Cerebral Palsy can affect different parts of the body, categorized in the following table. (Adapted from Jacobson, S., 2010). Table 1.1 Types of Cerebral Palsy, together with the affected areas Type of Cerebral Palsy| Area affected|
Monoplegia| One arm or one leg|
Hemiplegia| Both the arm and the leg on the same side|
Paraplegia| Both legs|
Diplegia| Paralysis of similar parts on both sides of the body| Quadriplegia| Both arms and both legs|
Dysarthria will be defined as a neurological motor speech impairment characterized by slow, weak, uncoordinated movement of the speech muscles (Yorkston, K. M., Spencer, K. A., Duffy, J. R., Beukelman, D. R., Golper, L. A., Miller, R. M, et. al., 2001). It is a result of damage to the central or peripheral nervous system that affects the transmission of neural messages to the muscles involved in speech. (Darley, F., Aronson, A., and Brown, J., 1975) Depending on the location of the lesion site, an individual may be diagnosed with different types of dysarthria. This is described in Table 1.2, adapted from Murdoch, B.E. (1998).
An individual with dysarthria may exhibit slow slurred speech, abnormal rhythm when speaking, mumbling quality in speech, and troubles with chewing and swallowing which is also referred to as dysphagia. (American Speech-Language-Hearing Association, 2009). In contrast to apraxia, a disorder which affects the brain's capacity to produce the "programs" necessary for coordinated motor movements, dysarthria results from an inability to send the proper messages to the musculature. While apraxia affects articulation (McCaffrey, P., n.d.), dysarthria can cause difficulty in the movement and control of any of the muscles used for articulation, phonation, or respiration (Morley, 1972). In an article by Neilson, P.D. and O'Dwyer, N.J., (1981) they stated that dysarthria in Cerebral Palsy may be a...