The questions on why most patients with Chiari Type 1 develop symptoms later in life and those who remain asymptomatic throughout a lifetime, have been long-standing. However, both make sense when looked at in terms of hypermobility. Our entire spines are held together and operate by means of connective tissues. HDCTs such as Ehlers-Danlos Syndromes (EDS), predispose these joints to become lax (loose). All things are not equal, however, so just as some joints tend to be laxer than others, some patients tend to have more laxity than others. With normal wear and tear, excessive wear and tear, or trauma (as most Chiarians develop symptoms following neck trauma (car accidents, etc.), these already predisposed joints often become even more lax, further compromising the very joints that are holding up the neck, cranium (skull), and everything within. Additionally, EDS patients are more prone to having other consistency problems and attribute to additional pathologies of an Acquired Chiari Malformation. Since collagen is the problematic protein with the EDS patient, and collagen is the “fibrous glue” that holds all our soft tissues together:

• Our organs lack the consistency to hold their shape, so they are more prone to prolapse.
• Our dura mater tend to be weak and are more prone to leaks (which can be spontaneous in EDS patients).
• As EDS patients, we accumulate an abundance of soft tissues (scar tissues, fatty tissues, etc). When these soft tissues form near the spine (especially the lower spine, but not exclusively the lower spine), they can adhere to the spinal cord or filum terminale, which creates a pulling effect on the spinal cord that can pull the brainstem down and everything can come down with it! When this tethering is allowed to continue over time, the tightness on the cord can become increasingly apparent.

For a more complete list of etiological/pathological cofactors, see: https://chiaribridges.org/overview-chiari-comorbidities-etiological-pathological-cofactors/