What is the key domain that differentiates AOS from pure apraxia of the limb?

• A. AOS affects speech motor planning; limb apraxia affects non-speech skilled movements.
• B. Limb apraxia affects speech, while AOS affects limb movements.
• C. AOS is a language disorder; limb apraxia is a memory disorder.
• D. Limb apraxia cannot co-occur with AOS.

Answer: (B)

The main idea here is that the key difference between AOS and pure apraxia of the limb is the domain of the impairment. AOS is a motor speech disorder, meaning the difficulty lies in planning and programming the movements needed for speech. Patients struggle with sequencing and timing of articulatory gestures, which shows up as distorted sounds, irregular timing, and inconsistent prosody, even when the underlying muscles aren’t weak. Limb apraxia, on the other hand, involves trouble planning and executing skilled movements with the arms and hands for non-speech tasks like gestures or tool use. Speech is typically not the primary problem in limb apraxia. So the defining contrast is whether the impairment centers on speech production or on non-speech limb actions. The other statements mix up these domains or make incorrect generalizations (for example, AOS is not a language or memory disorder, and limb apraxia can co-occur with AOS in some cases).