What did dr. mckhann observe in the children in beijing and why did this observation lead him to question the original diagnosis of guillain-barrã© syndrome?

I believe the answer is Children were not able to move but they did have sensory function.
The main cause of the Guillain-barra syndrome is the fact that patient's own immune system is attacking his/her own peripheral nervous system. 
The original diagnosis stated that the damage in sensory function would cause patient unable perceive sensations properly, but still able to make little movement.

The answer is to spread the world of christ