a question about King Mongkut

I have a question for all you out there who know Thai history. It is a known fact that King Mongkut was paralyzed on one half of the face. I would like to know where that came from? Was he born with it? Was it caused by an accident?

Does anyone know? I'd be thankful for an answer.

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We're all in the gutter, but some of us are looking at the stars.