Hirschsprung's disease query

[robertfw]

why is Hirschsprung's disease associated with a contracted aganglionic segment rather than relaxed dilated?

My understanding of Hirschsprung's disease is an aganglionic region of the sigmoid colon.

I also understand that there is an increase in acetylcholinesterase activity in the parasympathetic nerves in that region.

I understand the parasympathetic nerves are stimulatorary to the region, which I understand to mean causes contraction.
I also know that Hirschsprung's disease causes increased spasticity, i.e. continual contraction of the region.

Finally I understand the acetylcholinesterase inactivates acetylcholine preventing any further transmission.

Therefore, if acetylcholinesterase is high in the parasympathetic nerves causing a reduction in active acetylcholine, reducing nerve transmission from the stimulatorary parasympathetic nerves, how come the sigmoid colon is not constantly relaxed and dilated, as opposed to constantly contracted? Help please. Can anyone enlighten me?

[Simon]

I think because it has no innervation and it is smooth muscle, its 'basic' state is relatively inelastic.
Remember, the parasympathetic stimulation causes contraction AND relaxation; segmentation can only happen because both occur simulataneously in adjacent sections. So even if it was constantly relaxed there would still be no movement of food because there is no proximal contraction...do you see what I mean?

Google it. Johns Hopkins has a good site.