In our monthly newsletter, someone with PLS (the sort of MND I have) sent in this description by a chap called Galen trying to explain the condition. It’s rather good. (I hope he won't mind me quoting it verbatim. As you can tell he has a sense of humour - which is quite helpful in the circumstances.)
If I start telling people about upper and lower neurons I can almost see their eyes glaze over as they decide I must have some need to tediously explain PLS. They then avoid me. If I launch into how PLS may be a "gentler and kinder" form of ALS, or Lou Gehrig’s Disease, people often fixate on the ALS part and have even asked me why I'm not dead yet and how much longer do I expect to live. When I tell them I have a rare condition that causes a loss in communication between the brain and motor functions, most people feel I've been technical enough and sufficiently succinct.
If folks are still curious I can launch into examples. Walking over to a table to set down a glass of water is something that is done almost without thought by most people, however, the communication with my brain and the rest of my body has gotten so that I have to concentrate hard to even walk to the table. Trying to carry a glass of water is likely to overtax the limited capacity I have remaining, with the likely result being that both I and the glass will wind up on the floor. Or it can be more insidious. If I'm about to get out of a chair I may have devote virtually all of my resources into planning and executing exiting the chair, and may actually wind up ignoring anyone trying to talk to me while I try to stand. It isn't because others are boring or anything, rather I have to focus so hard on getting up, it blots out other things.
It's not a problem with the brain, we remain as sharp as ever. It's not our muscles, they work fine. It's communication between the two that is the problem. Walking requires intense communication with our balance sensors, our brain, our legs, feet, even our toes. Our consciousness isn't aware of it, yet it requires constant fine- tuning. Throw a monkey wrench into that communications system and you wind up with someone who can barely stagger anymore, a symptom many of us can relate to. Sometimes one side is affected more than the other, and you get someone like Ronnie, or it can be pretty symmetrical, like Flora, or it can add to an already serious personality disorder, like me.
It can have strange results. You can be at a funeral and your brain can be saying: "Whatever you do, don't make a scene," but because the message gets garbled, your mouth muscles say: "Roger, brain. Commencing uncontrollable laughter immediately." Or you can think you told your mouth to say to the UPS guy: "I'm feeling fine, and you?" only to have him look up at the sky and say: "You're right, it does look like rain."
We are constantly compensating, whether or not we are aware of it. Maybe that is why we get tired all the time "for no reason." We are always having to figure out new ways for our brain to signal our muscles to do stuff. Our brain may be so busy devoting time to keeping essential functions going that it can't worry about things like walking and talking.