Have you ever been involved in some form of surgery where you were put under local anesthesia? Have you ever considered that at some point you could wake up in the middle of surgery? It happens to few, but some patients where they are aware of what is going on, feel the pain, but cannot move to alert the surgeons that they are awake.
Here is one site's explanation:
WHAT IS ANESTHESIA AWARENESS?
Anesthesia Awareness is perhaps the most helpless and terrifying feeling in the world. It occurs when one is supposed to be completely asleep under full general anesthesia, but the brain is not asleep. Your body is almost always fully paralyzed; you have a tube down your throat; and you can't speak or move or do anything to alert the doctors that you are awake. If you do manage to move, as I did, a common response from the anesthesiologist is to simply administer another dose or doses of paralytic drug; not considering the possibility that the patient is awake; I.e. experiencing Anesthesia Awareness. New technology is available to monitor brain activity and has been proved in multiple scientific clinical studies to reduce the current incidence of anesthesia awareness, commonly calculated to be at least 100 cases per day, by at least 82%! This Campaign is working very hard to greatly further the use of such monitors in general anesthesia surgeries.
Ref. https://www.anesthesiaawareness.com/