Optic nerve decompression in osteopetrosis.

Osteopetrosis is a rare disorder characterized by generalized increased skeletal density with abnormalities of bone modeling. The skull base is usually involved. Loss of vision with optic nerve atrophy is the most common neurological finding and is traditionally believed to be the result of optic nerve compression within the compromised optic canal. However, retinal degeneration has recently been described and is hypothesized to be the etiology of the visual loss (thus challenging the value of surgical decompression). The authors report their experience with six children suffering from osteopetrosis and severe visual loss. All six patients underwent bilateral microsurgical optic nerve decompression through a supraorbital craniotomy. Improvement in visual acuity occurred postoperatively in five patients, and none had complications. Two technical points are emphasized: 1) optic nerve decompression should be wide and include not only unroofing of the canal but also drilling along both sides of the optic nerve, and 2) the thick, irregular, and highly domed orbital roof should be smoothed down by high-speed drilling to facilitate surgical exposure with minimal retraction of the frontal lobe.