Which statement best differentiates apraxia of speech from literal paraphasia?

• A. Phoneme and syllable substitutions in apraxia of speech tend to be close to the intended sounds, whereas paraphasias in aphasia are often off target.
• B. AOS is always caused by posterior brain damage, whereas literal paraphasia is caused by anterior damage.
• C. AOS is associated with normal prosody, while paraphasia always distorts prosody.
• D. AOS always coexists with aphasia, which is not the case for paraphasia.

Answer: (A)

When you hear a difference between motor planning problems and linguistic encoding problems, you’re looking at where the breakdown occurs: in apraxia of speech the motor plan for producing the sequence of sounds is faulty, so errors are approximations of what was intended. That means phoneme and syllable substitutions tend to sit close to the target—similar sounds are substituted or slight mis-sequencing occurs, even though effort and hesitations are evident. In literal paraphasia caused by aphasia, the issue is with choosing and assembling the correct phonemes at the linguistic level, so the errors can be less related to the target and more distant, sometimes producing sounds that aren’t as close to the intended word. So the distinguishing idea is that AOS errors stay near the intended sounds, while aphasic paraphasias are often off target. The other statements misstate typical lesion locations, prosody effects, or whether AOS must accompany aphasia.