Which syringomyelia is truly associated with multiple sclerosis?

Necrosis of the spinal cord within multiple sclerosis (MS) lesions was sugg ested as a putative cause of syringomyelic cavity development in MS. A numb er of evidences suggest however that mechanisms other than necrosis are pat hogenetically relevant for cavity formation, possibly depending on the atyp ical topographical distribution of the demyelinative lesion and on the incr eased cerebrospinal fluid pressure into the central canal below the compres sion. Not coincidentally, the hypothesis of post-necrotic and ex-vacuo mech anisms leading to cavitation derives from Japanese studies where MS is char acterised by high tissue destructive capability and, besides its rarity, ha s many differences from the more common Western MS type and similarities wi th the acute disseminated encephalomyelitis (ADEM). Our opinion is that dif ferent MS types (Asian and Western) are accompanied by nonuniform mechanism s of syrinx formation and that the Asian MS type shares common, post-necrot ic mechanisms with ADEM. (C) 2001 Elsevier Science B.V. All rights reserved .