Operative treatment is imperative as soon as septic thrombosis of the sinus has been diagnosed. This, however, is not always an easy matter. Sometimes, indeed, there are no clinical symptoms, the condition perhaps only being discovered whilst performing the complete mastoid operation as a prophylactic measure. The sinus is generally exposed accidentally whilst following out a tract of carious bone, and, to the surprise of the surgeon, pus or granulations may be seen to exude or protrude from an opening in its outer wall. On further exposure of the sinus on each side of the thrombus, the dura mater may appear to be of a dark colour for a short distance, but beyond this to be of normal appearance.
Seeing that there are no symptoms, the presumption is that the sinus is occluded on each side of the septic thrombus by a non-infective clot. It is, therefore, sufficient in such cases to simply excise the sinus wall over the septic area. If the case be so treated, it is essential that the sinus should only be curetted gently over the exposed opening, but otherwise left undisturbed. Also this limited operation should only be performed if the surgeon is satisfied that the septic focus is surrounded on each side by an organized normal clot—the condition in fact being treated as a simple abscess.
To secure free drainage, only the depth of the mastoid wound should be packed with gauze, the surface being protected by a simple dry dressing. The after-treatment is the same as that already described for the complete mastoid operation in which the posterior wound has been left open.
In other cases, if there be an acute inflammation of the mastoid process and if only one rigor has occurred, it may not necessarily mean that thrombosis of the sinus has taken place, as the rigor may be due simply to septic absorption. In such cases it is justifiable to delay opening the sinus if it is found to be exposed within the wound cavity and to be covered with granulations.
The bone, however, should be freely removed until the normal dura mater is reached, and the cavity afterwards rendered as aseptic as possible by syringing it out with hydrogen peroxide lotion. In a large proportion of cases a favourable result occurs, the pyrexia and head symptoms disappearing and an uneventful recovery taking place. On the other hand, gradually increasing pyrexia or a sudden rigor may occur, perhaps not until ten days or so after the primary operation, showing that the sinus has become infected after all. It should then be opened at once, but before doing so the jugular vein should be tied (see [p. 448]).
In a typical case, however, there is a history of repeated rigors, and in addition there may be attacks of vomiting and headache localized to the affected side, with pain and tenderness on pressure behind the mastoid process, and optic neuritis. In the more severe cases there may also be evidence of thrombosis of the jugular vein or cavernous sinus. It must, however, be remembered that a high and intermittent pyrexia, especially in children, may take the place of rigors. The principles of surgical treatment are to expose the sinus and remove the infective clot completely.
In connexion with this operation two points cannot be impressed too forcibly on the reader:—
1. The operation must be performed at once. The greater the experience of the surgeon the more he realizes that expectant treatment is nearly always fatal, and that a successful result depends largely on early and complete operative measures.
2. Before the sinus is interfered with in any way it is essential to obliterate its lumen below the thrombus in order to prevent any portion of it being swept into the circulation during its removal.