Like the many choices that medical editors make daily in their work, the decision when to use the possessive form when describing certain diseases/syndromes, tests, and anatomic terms demands a judicious evaluation of both author preference and common usage in the field in question. Of course the style guide of the particular journal or publisher should be consulted. The AMA Manual of Style, 10th edition, makes a good case for why dropping the possessive form in eponymous medical terms makes sense.
I knew the change to the nonpossessive form probably began with the shift from the term Down’s syndrome to the practically universal use today of Down syndrome. But I was surprised to learn the issue arose more than 70 years ago when the National Down Syndrome Society led the way, stating the syndrome did not belong to anyone and so was more appropriately expressed as nonpossessive. This idea is borne out in the opinion that many of these names should not be attributed solely to one person. In many cases other researchers have come along afterward and contributed just as much to our knowledge of a particular disease or condition.
Another consideration is the global reach of much medical research today. A short description of a syndrome in addition or in lieu of the name might be more useful to a worldwide audience.
Stedman’s Medical Dictionary has long suggested the nonpossessive form of eponyms. The 31st edition of Dorland’s Illustrated Medical Dictionary made the switch and dropped the “apostrophe s” in 2011.
Editors know that changes like the one discussed here may be the province of the written word long before they are used in common parlance. So we must proceed with caution, keeping our audience firmly in mind as we make editorial choices and remembering our primary goal is to serve our readers, easing their way through intricate and sometimes highly technical discussions of new research.