Posterior Scalloping of Vertebral Bodies in Uncontrolled Hydrocephalus.

The spinal canal normally increases in size until about the tenth year when the epiphyses fuse between the arches of the spine and the vertebral bodies. Enlargement of the canal after this time is manifested by flattening and thinning of the pedicles, increase in the interpediculate and saggital diameters of the canal, and posterior scalloping of the vertebral bodies. The majority of intraspinal tumours do not cause enlargement of the spinal canal because some tumours invade the vertebral bodies rather than enlarge the canal, and most intraspinal tumours produce marked neurological symptoms so that surgery is performed before changes occur in the pedicles of the vertebral bodies. Posterior scalloping of vertebral bodies with localized enlargement of the spinal canal usually denotes the longstanding presence of a mass lesion but scalloping occasionally occurs in patients without a mass lesion being present within the canal. Most of those patients having a vertebral scalloping but no mass lesion have generalized neurofibromatosis and the bone changes have been attributed generally to a non-specific mesenchymal defect or developmental failure of the vertebrae. The discovery of two patients with generalized posterior scalloping throughout most of the spinal canal associated with communicating hydrocephalus has prompted a review of the pathogenesis of posterior scalloping of the vertebral bodies. Two less striking cases have also been found.