In 2003 after a visit to the ER it was discovered that I have Multiple Sclerosis.
Multiple Sclerosis is an autoimmune disease. Basically my body is attacking itself by damaging the myelin sheath which protects the nerves in my brain. The result is lesions left in place where the myelin sheath was. I prefer to call them the holes in my head. There are many of them. Squatters who multiply occasionally by adding more squatters in my head. We're sort of one of those forever families and I have named many of them. Fred is the largest at 18 mm.
Your guess is as good as mine. It's not contagious. Over the years there have been many suggestions. I prefer to not know and go on with life.