Regardless of the debates and who is and is not right, the truth remains…

With the diagnostic criteria being what it is, we’re all being diagnosed with Chiari Malformation based on the placement of our cerebellar tonsils; from there it’s assumed that we’re congenital, without any measurements of our posterior fossa (to support that claim). Many of us are even told that we’re congenital, and we believe it because we’re taught to trust and respect our doctors. In nearly 100% of the Chiari diagnoses, a neurosurgeon won’t even look for other causal factors before performing a Posterior Fossa Decompression. Even when directly asked, they are quick to dismiss the idea without ever looking into it. So, an Acquired CM might not be all that “rare” at all, it might just be rarely diagnosed.

For more on these pathological (causal) cofactors: https://chiaribridges.org/chiari-malformation/