What's "Cantor's Sign"?

In David Foster Wallace's The Pale King, in the context of a list of medical ailments reference is made to "Cantor's sign (dextral)" and "Cantor's sign (sinistral)". Does anyone have any idea what this is referring to? I assume it has something to do with the hands, but found no mention of it anywhere on the internet.

Solution 1:

KitFox is probably right. "Sign" can be used in medical names of symptoms used for diagnosis. It's likely the author made one up using that template. See this list for real examples: http://en.wikipedia.org/wiki/List_of_eponymous_medical_signs

The terms in parentheses are not referring directly to the hands, but rather which side of the body the symptom occurs on ("dextral" for the right side, "sinistral" for the left).