Experimental production of arachnoiditis with water-soluble myelographic media.

After myelography with either metrizamide (300mg l/ml) or meglumine iocarmate (280 mg l/ml), mild to severe arachnoid fibrosis was demonstrated radiographically and histologically in primates. Intrathecal injections of metrizamide (170 mg l/ml) or autologous cerebrospinal fluid produced less arachnoiditis. The risk of arachnoiditis is probably minimized by the use of reduced volumes and concentrations of water-soluble media. Controlled studies of arachnoiditis following myelography are probably more reliable in the primate model than in other experimental animals.