Engelmann's disease.

A 5-year-old boy with diaphyseal dysplasia who exhibited marked involvement of the cranial bones developed marked disk edema in a one-year period. We believed the optic canal was being rapidly compromised by bony proliferation and vision was threatened. Selective bone studies, including tetracycline labeling, demonstrated a rapid accretion of bone 1 1/2 to two times the expected rate for his age. We performed bilateral unroofing of the optic canals with additional temporal decompression of the left orbit. Limited unroofing of the right eye proved to be inadequate and only with additional extensive temporal decompression was the disk edema of the left eye reversed. Tomograms taken one year after surgery revealed regrowth of bone in the optic canal and orbital roof. The usefulness of bony decompression of the orbits in Engelmann's disease is requestionable.