title: Ball-valve and cyst formation.
authors.forename: B
authors.initials: B
authors.lastname: Williams
mesh_terms: D003560:Cysts / Q000209:etiology*; D006801:Humans; D008578:Meninges; D013122:Spinal Diseases / Q000209:etiology*; D013126:Spinal Nerve Roots / Q000502:physiology