Calcification and ossification of the spinal arachnoid after intrathecal administration of Depo-Medrol.

A woman 38-year-old, suffering for about ten years from multiple sclerosis and treated with repeated therapy cycles of intrathecal Depo-Medrol, developed a spastic paraparesis at the lower limbs. A lumbar myelography was carried out, and a dorsal block was demonstrated. The patient underwent a dorsal laminectomy, and arachnoidal calcification and ossification was find, but the removal of the bone plaques was ineffectual in order to the subsequent course of the neurological troubles. The results of the histological study and chemical tests are reported, and the etiology and the pathogenesis are discussed on the basis of the pertinent literature.