I do not understand why stephen w. meldon, in their article of march 2000, says that in chronic sdh the interval from time of trauma to presentation is up 12 years; while in 3 most recent articles(total about 1500 cases), this interval is up 3 months?

In medicine a lay people should forget what you were told more than 10 years ago. Even us, as doctors, we needs to be re-certified every 7-10 years for updated knowledge or at least we have to read almost daily for medical news.

It has to do with references "The interval from time of trauma to presentation is variable, ranging from three weeks to 12 years" with 12 years being the maximum as found in the literature.

So-called late subdural hematoma from recent head trauma occurs within a few weeks. A diagnosis of SDH beyond a few months would either represent discovery of a chronic bleed or a new event Most neurological docs would search for a new explanation at 12 yrs