Hey everyone, I thought I would post this for the whole group so it doesn't get lost in the comments. :)
This is from an obstetrician in my area who is notoriously pro-doula, pro-natural birth, pro-midwives... All us birthy types drool over him whenever he comes to one of our meetings. :) Anyway, I asked him if he had any knowledge of Arnold-Chiari Malformations and if he could clear up whether it's an automatic cesarean or if a vaginal birth is possible. Here's his response! (Lingo translation: C/S is cesarean, MFM is maternal/fetal medicine, 2nd stage is the pushing stage of labor, you all know what ACM is!)
"The short answer to your question is that, yes, most MFM (maternal fetal medicine "perinatologists") will recommend C/S to avoid intracranial pressures during 2nd stage and hopeful avoidance of increasing any brain herniation. That said, there are a number of non-ACM conditions where this is the goal, and sometimes you can find an MFM who works with an OB/GYN that will allow a "low-pressure" vaginal delivery. This usually includes an "assisted" 2nd stage, meaning letting the uterus doing most of the work (getting the baby's head really really close to crowning all by itself, without pushing), and then using either a vacuum or forceps for the final push. I've done this with certain cardiac and spinal-cord injury patients with great success."
I knew that the pushing was the problem, since it's just another valsalva maneuver (like straining when you poo, yawning, etc. - all those things that give us our pressure headaches). If you are proactive it's possible to find a doctor who will allow you to labor up to 10cm, and then they will help get baby out quickly to avoid as much pressure on the brain as possible. That's said, if you are more comfortable with a cesarean birth, it's probably safer on your brain, but cesareans come with risks, too. It's up to every family to weigh the pros and cons and choose what's best for them.
Good luck, Chiari mommas!
Katrina W.
CLD (CBI), CLE, CBE
(look, I have credentials!)