Which syringomyelia is truly associated with multiple sclerosis?

Necrosis of the spinal cord within multiple sclerosis (MS) lesions was suggested as a putative cause of syringomyelic cavity development in MS. A number of evidences suggest however that mechanisms other than necrosis are pathogenetically relevant for cavity formation, possibly depending on the atypical topographical distribution of the demyelinative lesion and on the increased cerebrospinal fluid pressure into the central canal below the compression. Not coincidentally, the hypothesis of post-necrotic and ex-vacuo mechanisms leading to cavitation derives from Japanese studies where MS is characterised by high tissue destructive capability and, besides its rarity, has many differences from the more common Western MS type and similarities with the acute disseminated encephalomyelitis (ADEM). Our opinion is that different MS types (Asian and Western) are accompanied by nonuniform mechanisms of syrinx formation and that the Asian MS type shares common, post-necrotic mechanisms with ADEM. (C) 2001 Elsevier Science B.V. All rights reserved.