A System of Operative Surgery Part 71

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.

EXPOSURE OF THE LATERAL SINUS

=Indications.= (i) In doubtful cases to decide whether thrombosis exists or not.

(ii) As a preliminary to opening the sinus with or without ligature of the jugular vein.

=Operation.= The first step is to perform the complete mastoid operation, except in the case of acute inflammation of the mastoid process, when Schwartze's operation will be sufficient.

To expose the field of operation more freely, an incision an inch or more in length is made horizontally backwards, beginning at the mid-point of the posterior margin of the primary incision (Fig. 216), the soft parts being reflected upwards and downwards from the bone, and the flaps so formed being then retracted. Above, the bone should be exposed beyond the level of Reid's base-line, which roughly corresponds to the line of the transverse sinus; below, the tip of the mastoid should be cleared until the mastoid vein is reached. If it be thrombosed it may be a.s.sumed that the lower part of the lateral sinus is also thrombosed. Bleeding from the bone at this point may be arrested by temporarily plugging the foramen with a fragment of sterilized wax.

The condition found on opening the mastoid process varies considerably.

If the result of acute inflammation of the mastoid process, the mastoid cells surrounding the sigmoid sinus usually contain pus or granulations, on removal of which a fistula may be seen to communicate with the outer wall of the sinus; or the bone around the sigmoid groove may already be destroyed, with free exposure of the sinus within the wound. With this there is frequently an extra-dural abscess. In other cases, if the infective process has been very virulent, evil-smelling pus, sometimes intermixed with bubbles of gas, may escape on chiselling through the mastoid cortex. This is a sure sign of extensive disease, the sinus wall often being gangrenous and the bone surrounding it necrosed and discoloured.

If occurring in the course of a chronic middle-ear suppuration, very little disease of the mastoid process may be found except along the path by which the infection has spread.

After the sinus wall has been reached, sufficient bone should be removed to expose its outer surface for at least half an inch above and below the supposed infected area.

The decision as to whether thrombosis exists or not may have to be made during the operation itself, and is based partly on the appearance of the sinus wall and partly on the symptoms, the relative value of each varying in each individual case.

Normally the sinus pulsates and is of a bluish-grey colour. If thrombosed, the wall of the sinus may be of a yellow or dark colour and may not pulsate, but neither discoloration nor the absence of pulsation is an absolutely reliable sign of thrombosis. Again, if the sinus be covered with granulations or purulent lymph, it is sometimes impossible to say whether it is thrombosed or not, especially if the clot is limited and parietal. Further, the thrombus may be situated low down towards the jugular bulb, so that if it has not extended very far upwards the exposed portion of the lateral sinus may still be normal in appearance. Palpation of the sinus with the finger or aspiration with a hollow needle is sometimes advised as an aid to diagnosis. These procedures, however, are extremely unwise, owing to the risk of dislodging a small fragment of the infected clot, which may easily occur if the latter does not obliterate the sinus completely. As a means of diagnosis the withdrawal of blood by the aspirating needle is of no value, as it does not negative the presence of a parietal thrombus, owing to the possibility of the needle pa.s.sing through it into the free lumen of the sinus.

OPENING OF THE LATERAL SINUS

=Indications.= The sinus should always be opened as soon as it is certain that septic thrombosis has occurred.

=Contra-indications.= The only contra-indication for opening the sinus and removing the thrombus is the certainty that either the patient's general condition will not permit of the operation being performed, or that the septic thrombosis has spread beyond the region from which it is possible to remove it.

For this reason, operation is unjustifiable if the patient is already suffering from septic pneumonia, pericarditis, or acute septicaemia; or, on the other hand, if there are symptoms of cavernous sinus thrombosis on both sides, or general meningitis. If, however, the patient's general condition be good, operation may be attempted as a last resource even although a pulmonary empyema or a one-sided cavernous sinus thrombosis already exists.

=Operation.= After exposure of the lateral sinus, the next point to determine is the site and extent of the infected area (Fig. 244). On this will depend whether it will be necessary or not to tie the jugular vein in the neck.

The sinus is first exposed towards the jugular fossa until its surface appears normal for at least half an inch. It is wiser, however, always to expose the sinus as low down as possible. A strip of sterilized gauze is then pressed in between the bone and the outer wall of the sinus so as to obliterate its lumen at this spot. Instead of removing the bone from above downwards, the sinus may be exposed first at its lowest limit by chiselling directly through the tip of the mastoid process. In this way it can be obliterated by a strip of gauze before attacking the area of infection. The overlying bone is afterwards removed from below upwards until the thrombosed area is reached.

In removal of the bone from above downwards there is a certain risk of small particles of clot being dislodged into the circulation, or, if the sinus wall is injured, of haemorrhage taking place if the thrombus at this particular point does not completely occlude the sinus. If, however, the sinus be first exposed and obliterated at its lowest limit, these risks are greatly minimized. There is no special technique in removing the bone beyond that already given in the description of the complete mastoid operation.

The next step is to expose the lateral sinus behind the infected area and follow it backwards until the dura mater appears normal for at least three-quarters of an inch. If necessary, the skin incision must be prolonged still farther backwards, in order to permit of removal of the bone overlying the transverse sinus, which may, perhaps, have to be exposed even to the torcular Herophili.

[Ill.u.s.tration: FIG. 244. DIAGRAM TO SHOW THE USUAL POINTS AT WHICH THE LATERAL SINUS IS PRIMARILY INFECTED. A, High up; from the posterior mastoid cells. In this case it may not be necessary to tie the jugular vein. B, Low down; involving the jugular bulb. This necessitates ligature of the vein.]

In removing the bone overlying the infected thrombus, the gouge and chisel should be used rather than the bone forceps or burr. With the latter there is greater risk of dislodging particles of clot into the circulation, owing to pressure of the instrument on the sinus wall.

After the sinus has been exposed well beyond the region of the thrombus, the bone forceps may safely be used, especially in exposure of the transverse sinus; and this is a much more rapid method than removing the bone by means of the gouge and mallet. To prevent the inner blade of the forceps from nipping the sinus wall between it and the bone, the dura mater forming the outer wall of the sinus should be separated from the overlying bone by means of a dura mater separator. In the region of the infected area the sinus wall may be adherent to the bony wall as a result of the inflammatory adhesions, and, in addition, may be extremely friable and so easily torn through.

In exposure of the sinus two points should be remembered: firstly, that it is sometimes difficult to differentiate it from the dura mater covering the temporo-sphenoidal lobe above and the cerebellum below; and secondly, that the transverse sinus is a very much broader vessel than is imagined, being even half an inch in width. Not much force is required to obliterate its lumen, but care must be taken to pack the gauze evenly across its whole width.

After the sinus has been occluded above and below the area of infection, it should be incised with a small knife along its whole length between the obstructing plugs of gauze (Fig. 245). If there be bleeding, it may be due to the sinus being obliterated incompletely, or it may come from the superior petrosal sinus. To find out where the bleeding comes from, the finger should be pressed upon the sinus at its upper and lower limits, close to the obstructing plugs of gauze. If the bleeding stops, it shows that the sinus has not been obliterated completely; this can now be done by further plugging with gauze. If, in spite of this, bleeding still continues, it presumably comes from the petrosal sinus.

All clot and granulations are now rapidly curetted out and the lateral sinus plugged with gauze. After a moment the gauze is withdrawn and another small piece is pressed into the lateral sinus at the point of entrance of the petrosal sinus. After the bleeding has been arrested, the outer wall of the lateral sinus is excised by cutting it away with blunt-pointed scissors. The interior of the sinus is then inspected, special attention being given to the lower portion to see if its lining is normal. If this be not the case, even if there be no signs of thrombosis, it means that the surgeon has failed to get well below the infected area, and therefore the internal jugular vein must be ligatured. If, however, it be normal, the gauze plug already placed between the sinus wall and the overlying bone is left undisturbed.

If there be no bleeding from the sinus (excepting a slight amount from the blood contained within the isolated portion), the thrombus is curetted out and the inner surface of the sinus inspected. After excising the outer wall, search is made for the superior petrosal sinus, which presumably is thrombosed, although perhaps only by normal clot. To expose this tributary, which enters the lateral sinus at the point at which it turns downwards to form the sigmoid sinus, bone must be removed in front of the lateral sinus along the angle forming the roof and inner wall of the mastoid and antrum; that is, along the superior margin of the petrosal bone. If the inner surface of the lateral sinus in its neighbourhood be normal, nothing need be done. If, however, the sinus wall be infected, the petrosal sinus should be followed out, if possible, its outer wall being incised and the clot removed, bleeding being afterwards arrested by pressure.

[Ill.u.s.tration: FIG. 245. THE LATERAL SINUS EXPOSED AND OPENED. The lumen of the sinus is obliterated above and below the region of the infected thrombus by plugs of ribbon gauze pressed in between the sinus wall and the overlying bone. In this case it is not necessary to tie the jugular vein.]

As a final step, the gauze plugging which still obliterates the lumen of the sinus in its upper part is removed. If the sinus be normal at this point, free haemorrhage will occur; this is arrested at once by again introducing a strip of gauze between the sinus and the bone. Although during the earlier stages of the operation the inner lining of the posterior portion of the sinus may have seemed to be normal, yet it occasionally happens that haemorrhage does not at once occur on removing the plug of gauze; but after a moment or two a long smooth clot, gradually tapering at its end, may be shot out from the opening within the sinus, being followed by a gush of blood. The terminal portion of this clot is non-infective and of recent formation. Its appearance is always a matter of satisfaction, as it means that the sinus has been freely exposed and opened behind the infected area.

If on exposure of the sinus it be found that the clot extends so low down that it will be impossible to obliterate the sinus well below the infected area, the jugular vein should be ligatured at once before interfering further with the sinus from the mastoid wound.

Attempts to remove the clot from the jugular bulb by curetting out the sinus from above are only referred to to be condemned. The surgeon who believes in this method hopes that all the infected portion of the clot will be swept out by the flow of blood. It is not, however, always possible to introduce a curette into the jugular fossa, and if the clot extends beyond this region it cannot be curetted away completely. The result of the operation does not depend so much on the skill of the surgeon as on whether the terminal portion of the clot be infected or not. Recovery is most likely to take place if a non-infective clot already extends beyond the region of the curette and so obliterates by natural means the lumen of the vein below the point reached by the surgeon. If, on the other hand, free haemorrhage occurs as a result of the curetting, it means that the lumen of the vein has been restored, but there is no guarantee that all the clot has been completely removed.

If any infective portion remains, a fatal result will almost certainly occur eventually as the result of pyaemia.

LIGATURE OF THE JUGULAR VEIN

=Indications.= Unfortunately, opinion is not unanimous with regard to this matter. The chief arguments raised against ligature of the jugular vein are: (1) That it favours extension of the thrombus along the veins communicating with it, especially along the inferior petrosal and condyloid veins, which enter the jugular bulb. (2) That it in no way prevents the spread of infection along other paths, owing to the freedom with which its tributaries communicate with one another. (3) As a result of obstruction in the circulation, acute inflammation of the cerebellum may take place.

Since the jugular vein should only be ligatured if the symptoms point to the onset of a general infection of the circulation and if it be found impossible at the time of operation to obliterate the sinus below the infected thrombus, and since this vein is the chief route by which this infection takes place, it seems a matter of common sense that it should be ligatured. At the same time, as many as possible of its tributaries above the point of ligature should also be ligatured well beyond the point at which they may be thrombosed.

Although extension of the infection may take place along other veins after ligature of the jugular vein, it is impossible to say whether the result is _post_ or _propter hoc_. Against ligature, statistics have been quoted to show that in a series of cases in which the jugular vein has not been tied the percentage of recoveries is just as high as in those in which it had been ligatured. This argument is not quite sound, because there is no doubt that in the cases in which ligature of the jugular vein is justified the chances of recovery, owing to the extension of the thrombus downwards, must be less than in the less serious cases in which it is admittedly unnecessary to tie the vein. It is also impossible to say how many cases would otherwise have ended fatally if ligature had not been performed.

In the majority of cases the vein is ligatured after exploration of the lateral sinus. In a few cases, however, the symptoms warrant it being performed as a primary step of the operation, even before the mastoid process has been opened.

=After exposure of the lateral sinus.= (i) If the clot extends so low down that it is impossible to obliterate the lumen of the sinus below its lower limit.

(ii) If there be thrombosis of the bulb of the jugular vein. This condition is sometimes difficult to diagnose. There may be no symptoms excepting, perhaps, rigors occurring during the course of chronic middle-ear suppuration, as even the lower portion of the sinus may be quite normal in appearance owing to the clot being limited entirely to the jugular bulb. The probability of the diagnosis being correct is strengthened by the presence of granulations or carious bone on the floor of the tympanic cavity. It is better to risk tying a normal vein than to fail to tie one already infected.

(iii) If the sinus was obliterated above the jugular bulb at the primary operation and rigors occur subsequently, showing that the sinus is infected still lower down.

=Before exposure of the lateral sinus.= (i) If there be thrombosis of the jugular vein. In addition to the ordinary signs of lateral sinus thrombosis, there may also be infiltration of the tissues, or tenderness along the anterior border of the sterno-mastoid muscle. The prevalent idea that a thrombosed jugular vein can be felt on palpation as a hard cord extending down the neck is erroneous. If anything be felt it is probably some enlarged cervical glands lying along the line of the vein.

In any case it is bad practice to palpate the internal jugular, as by doing so there is considerable risk of dislodging particles of the septic clot.

(ii) If, as a result of septic infection, the general condition of the patient be so serious that a prolonged operation seems unjustifiable. In such cases, the lateral sinus is rapidly exposed and incised after tying the internal jugular, its contents are curetted out and the wound cavity lightly plugged; the completion of the operation, consisting of the opening up of the mastoid cells and antrum, and possibly also exploration of the intracranial cavity, may be performed next day or later.

(iii) If it be doubtful whether septic thrombosis of the sinus has already occurred, it is justifiable in certain cases merely to expose the sinus freely and not to open it (see p. 440). If rigors subsequently occur in these cases and it becomes evident that the sinus has become infected after all, then it is wiser to tie the jugular vein as a primary step of the operation before opening up the sinus itself.

The writer's reason for doing so is, that at the second operation he has always found the clot to be extensive, or, at any rate, to be situated so low down as to prevent the sinus being obliterated below the infected area.

[Ill.u.s.tration: FIG. 246. INCISION FOR EXPOSURE OF THE INTERNAL JUGULAR VEIN. The ill.u.s.tration shows the superficial structures. A, Common facial vein; B, Fascia covering the hyoid bone; C, Anterior border of the sterno-mastoid muscle; D, Omo-hyoid muscle.]

=Operation.= Formerly it was considered sufficient to divide the vein between two ligatures and to leave it _in situ_. Now, however, the upper portion of the vein is brought out through the wound in the neck after this has been done.

The patient lies in the rec.u.mbent position with the affected side close to the edge of the table. The head and shoulders should rest on a hard pillow in such a fas.h.i.+on that the neck is slightly extended, the chin being drawn upwards and the head turned a little to the opposite side so that the anterior border of the sterno-mastoid muscle can be clearly defined throughout its whole length. The surgeon stands at the side to be operated on. The neck is carefully cleansed, but in doing so care should be taken not to rub the neck too violently, nor should any attempt be made to palpate the line of the jugular vein in the hope of feeling it. There is no object in doing so, and if it is thrombosed a portion of the clot may be dislodged.

An incision, at least three inches in length, is made along the anterior border of the sterno-mastoid muscle, the mid-point of the incision corresponding to about the level of the cricoid cartilage. On cutting through the skin and platysma some small veins may be met with: they should be clamped with forceps and divided. If, however, the anterior jugular vein be exposed, it should be drawn to one side, if possible, and not divided. The anterior border of the sterno-mastoid muscle is clearly defined, until the upper border of the omo-hyoid muscle is reached (Fig. 246). Its edge is then drawn slightly outwards by means of a retractor and separated from the underlying deep fascia. Beneath this fascia is the carotid sheath, which encloses not only the carotid artery but the internal jugular vein and the vagus nerve. The vein is external and somewhat superficial to the artery, and the vagus nerve lies behind.

A vein of varying size will be seen crossing obliquely downwards and outwards to pierce the deep fascia at a level corresponding to the cornua of the hyoid bone; this is the common facial vein about to enter the internal jugular (Fig. 247). If the surgeon has not had much experience and has difficulty in finding the jugular vein, a certain method of doing so is to find the facial vein and then follow it down until it enters the jugular. The carotid sheath should be opened about this point, and the position of the vein ascertained by feeling the pulsations of the carotid artery. The sheath of fascia covering the jugular vein is picked up with a pair of fine forceps and cut through with a sharp scalpel, which should be inclined obliquely outwards so that the flat of the knife is held towards the vessel. Any enlarged lymphatic glands lying over the vein must be removed.