Posterior fossa morphometry in 170 South Asian children and adults with Chiari malformation and its correlation with tonsillar descent.

Patients with CM1 have significantly shorter clival length and posterior fossa height with smaller posterior fossa in support of published data. The presence of BI shortens the posterior fossa height and worsens the extent of tonsillar herniation. An increased Boogard's angle and FM angle result in a more horizontally placed suboccipital bone compared to a slanting bone in normal persons.