The frequency with which the sigmoid sinus is involved in middle-ear inflammations is greater than was formerly suspected. This advance in our knowledge can be attributed to several factors: the more radical technic in operating on the mastoid and thus laying bare and exposing an unsuspected diseased sinus, and the comprehensive diagnostic aids which we resort to in interpreting the true condition underlying unusual cases of middle-ear inflammation. There is, however, one fact to be borne in mind—that the severity of an acute or chronic purulent inflammation is not the only cause of the possible extension of the original disease into the neighboring venous channels.
It is very possible for a mild acute inflammation of a very short duration, when the pain and discharge cease, to be followed in a few days by such serious complications as phlebitis and thrombosis of the sigmoid sinus. During this interval of apparent well-being,