Was this some form of dyslexia (or more correctly, dysgraphia), do you know?

As another person noted, it's a good chance he wrote as he did to hid his ideas and inventions. On top of that, though, is the fact that he studied things that were outlaw at the time. Like cutting up cadavers to gain anatomical knowledge (he had to sneak them into his place for study). The favor of nobles isn't enough if you're crossing the current day boundries of taste, religion and law.

From studying him, I can just imagine how lonely a person he was, being unable to express what he understood about science, engineering, biology, etc.

Ali