label: Craniocervical junction constriction
label_lc: craniocervical junction constriction
description: "Congenital or acquired abnormalities of the occipital bone, foramen magnum, or first two cervical vertebrae that decrease the space for the lower brain stem and cervical cord. These malformations can lead to cranial nerve compression, vertebral artery compression, and obstructive hydrocephalus."