Emilie Lucchesi in Discover:
After a retired speech-language pathologist had a stroke, he struggled to articulate his thoughts, even though he knew what he wanted to say. His wife didn’t understand the source of his difficulties until a clinician showed her a video that explained what her husband wished he could tell her: His stroke caused apraxia. Apraxia is a term used to describe a list of neurological disorders that impact speech, movement or gestures. Clinicians have observed apraxia for centuries, but they still don’t agree on which symptoms belong to which disorder type, and controversy persists.
What Is Apraxia?
Apraxia is a term used to describe a series of conditions that make it difficult or impossible for a person to perform a desired movement or gesture. Depending on the person, apraxia can mean they struggle to make facial expressions in response to vocal commands.
More here.