Apraxia of Speech: Two Sides of the Same Coin?

Childhood apraxia of speech has recently been in news headlines that detail walks, benefits, and celebrities affected in order to raise awareness and funds for this disorder. Apraxia of speech is a disorder that affects both children and adults and presents itself as either developmental or acquired apraxia of speech (AOS).

Apraxia of speech is a disorder where the messages from the brain to the articulatory muscles become disrupted, causing the individual to have difficulty producing sounds correctly, or at all. It is important to note that this is not caused by muscle weakness. Individuals with AOS often describe knowing what they want to say, but not being able to produce the correct words or sounds. In face, inconsistency of articulation is a main characteristic of AOS.

Researchers and professionals in the field often debate whether developmental apraxia of speech (DAS) and acquired apraxia of speech (AOS) are fundamentally the same disorder or separate disorders entirely (Maassen, 2002).

The main difference between the two types of apraxia are the time of onset. With DAS it is assumed that the disorder is present from birth, even before symptoms appear; whereas an acquired apraxia is caused by damage to a previously  normal speech system. This damage can be caused by traumatic brain injury (TBI), dementia, brain tumors, or progressive neurological disorders. Though most patients with the acquired form are adults, it is possible to acquire this disorder at any age depending on when the brain is injured.

It is important to understand this difference between acquired apraxia and developmental apraxia as therapy is approached differently depending on the etiology. Patients with AOS have an existing framework for higher level language and phonological development that a speech-language clinician can utilize during therapy. This is contrasted by developmental apraxia of speech where the child does not have a developed cognitive-linguistic framework supporting speech output. As a result children often have additional comorbid problems including delayed language development, expressive language deficits, and discoordination of motor movement (ASHA, 2015b). With either developmental or acquired apraxia, intervention is critical for optimizing communicative outcomes for these individuals.
References

American Speech-Language-Hearing Association. (2015a). Apraxia of speech in adults. Retrieved fromhttp://www.asha.org/public/speech/disorders/ApraxiaAdults/

American Speech-Language-Hearing Association. (2015b). Childhood apraxia of speech. Retrieved fromhttp://www.asha.org/public/speech/disorders/ChildhoodApraxia/

Maassen, B. (2002). Issues contrasting adult acquired versus developmental apraxia of speech. Seminars in Speech and Language, 23(4), 257-266. doi:10.1055/s-2002-35804

National Institute on Deafness and Other Communication Disorders, (2002). Apraxia ofspeech. Retrieved fromhttp://www.nidcd.nih.gov/health/voice/pages/apraxia.aspx