Hence the quick edit to clarify a very important secondary opinion regarding medically assisted suicide.

Also I didn’t feel it necessarily to mention, but there are established protocols for communication with locked in patients. Effectively you explain to them you know they are locked in and work to develop any effective feedback loop, be it brain wave biofeedback, blinking, or anything else.

Once you can reliably ask yes no questions (and trust you aren’t miss interpreting the patient) you can eventually get to important questions like “do you want to live like this?”