In this connexion must be mentioned--(1) Serous meningitis: a name given to an increase of the cerebro-spinal fluid within the subdural or subarachnoid s.p.a.ce, or the ventricles, the hypersecretion being probably caused, as Merkens suggests (_Deutsche Zeitsch. fur Chir._, vol. lix), by the toxic infection induced by the suppurative focus in contact with the external surface of the dura mater. The symptoms of serous meningitis may closely simulate an intracranial abscess or a purulent meningitis, except that frequently there is no pyrexia. (2) Purulent meningitis, which may be diffuse or localized. (3) Pseudo-meningitis: that is, a condition simulating meningitis but in reality due to irritation of the meninges as a result of suppuration still confined within the temporal bone--for example, the result of acute middle-ear suppuration in infants.

Clinically it is often difficult to determine before operation which variety is present.

=Indications.= Operation is indicated as soon as the onset of meningitis has been diagnosed and should be performed without delay. Waiting for all the cardinal symptoms of meningitis to occur will never save life.

The only possibility of doing so is to operate while the inflammatory process is still localized. At the same time it must be recognized that whenever symptoms of meningitis occur the prognosis is most serious.

Lumbar puncture should always be performed as an aid to diagnosis. If the cerebro-spinal fluid be clear and sterile, diffuse meningitis can usually be excluded, although at the same time it must be remembered that it does not negative a localized meningitis without increased intracranial pressure. Increased flow of cerebro-spinal fluid indicates increased intracranial pressure, perhaps the result of serous meningitis. Slight turbidity suggests early purulent meningitis, especially if bacteria are present, but not necessarily that the case is hopeless. If the fluid be definitely purulent, operation may be considered out of the question; a case, however, has been recorded in which recovery took place.

The value of cytological examination of the fluid is still doubtful.

Marked increase of polynuclear cells is said to point to acute and intense inflammation, whereas an abatement of the polynucleosis may be taken as a sign of diminution of the meningeal irritation. With this, increased leucocytosis, increasing as recovery progresses, may be looked upon as a hopeful sign.

If it be obvious that the patient is dying, not only from the local infection but also on account of general septic absorption, operation, of course, is excluded. Similarly, at the present time, post-basic meningitis of infants is rightly deemed inoperable.

=Operation.= Although no set operation can be described, the principles of the operation are to expose the infected area widely so as to allow of free drainage and, at the same time, to relieve intracranial pressure. The extent of the operation will therefore depend largely on what is found during the course of the operation itself.

1. In an infant or young child, if the symptoms develop in the course of an acute ot.i.tis media, the tympanic membrane should first be inspected to see if there is sufficient drainage. If not, it should be freely incised, and opening of the antrum and mastoid may be delayed for at least twelve hours.

2. In an adult, immediate exploration of the mastoid and antrum is indicated on the onset of meningeal symptoms, even although they occur during the course of an _acute_ middle-ear suppuration.

If the symptoms of meningitis in these cases be as yet indefinite, and if pus be found under tension within the mastoid cavity, or if an extra-dural abscess exists, the dura mater should not be incised at once, but a delay of twenty-four hours should be advised; in many cases complete recovery will take place. If, however, the symptoms continue, intracranial exploration will be necessary.

3. In chronic middle-ear suppuration, meningitis is usually secondary to, or accompanies, other intracranial complications or internal-ear suppuration, the symptoms of which it may mask.

After performing the mastoid operation any tract of carious bone is followed out to its limits.

According to what he finds, the surgeon may first expose the dura mater covering the lower portion of the middle fossa (Fig. 243), or of the posterior fossa behind and in front of the lateral sinus; these are the usual sites of infection. The removal of bone must be free, in order to get well beyond the limits of the infected area, if possible. The dura mater is incised to the limits of its exposure either crucially or by cutting it through in the form of a large flap.

The dura mater is usually congested, but if an extra-dural abscess or lateral sinus thrombosis be present, it may be thickened and of a leathery appearance; or in the latter case almost gangrenous.

The further steps depend on the conditions met with on incision of the dura mater.

[Ill.u.s.tration: FIG. 243. METHOD OF REMOVAL OF BONE BY THE FORCEPS. In this instance the bone is being removed above the tegmen tympani in order to expose the lower portion of the middle fossa.]

1. _In serous meningitis_ a certain amount of clear fluid may escape and the brain surface may be only slightly congested. After removal of the bone and of the dura mater over the infected area the surface of the brain should be scarified in various directions to make certain that the pia-arachnoid has been incised, and fine drainage tubes should be inserted between the latter and the dura mater. In these cases a hernia seldom occurs, although the brain surface may bulge slightly into the wound.

2. _In purulent meningitis_ the surface of the brain is usually covered with turbid fluid or purulent lymph, which may be localized to the site of the diseased bone, or may have spread from this point to a varying extent over its surface.

If the limit of the infection cannot be reached, in spite of removal of a considerable extent of bone and dura mater, all that can be done is to irrigate the exposed area with warm saline solution and to insert fine drainage tubes between the brain and dura mater, at the same time (as in the case of serous meningitis) incising the meninges in various directions.

3. _Purulent lepto-meningitis_ is usually accompanied by encephalitis.

If localized by adhesions an acc.u.mulation of pus may occur, forming an abscess on the surface of the brain, which also may be superficially ulcerated or necrosed. If there be intracranial pressure from encephalitis, the brain tissue usually protrudes as a dark, haemorrhagic friable ma.s.s, in which shreds of necrotic brain tissue will be seen. In other cases, if there be no increased intracranial pressure and if the condition be quite localized, no hernia may occur, but the surface of the brain may be rough or eroded.

Any purulent secretion should be removed by irrigation, care being taken not to disturb the brain more than is necessary, so as to diminish the risk of breaking down the surrounding adhesions. A hernia may or may not form immediately. If no hernia takes place, it is wiser to do nothing further; that is, provided sufficient bone and dura mater have been removed to reach the limits of the infected area. Some authorities, however, consider that the necrosed portion of the brain should be curetted out. Although in other parts of the body the removal of necrosed tissue is a proper procedure, yet in the case of the brain there is considerable risk of setting up further dema or septic cerebritis, the progress of which may have become arrested at the time of the operation.

If the inflamed brain tissue protrudes to an excessive degree during the operation itself, the opening in the skull should be enlarged, if it be not already of considerable magnitude, and the dura mater incised to the full limits of the opening. The protruding ma.s.s may then be cleanly excised by means of a scalpel. If, however, the brain tissue continues to prolapse, the wound cavity should be simply cleansed and protected by a dressing of sterilized gauze. If the encephalitis subsides, the hernia will not increase in size, and if the wound cavity be kept aseptic, it may gradually shrink.

=After-treatment.= This consists in covering the wound surface lightly with gauze so as to permit of free drainage, and changing the dressing as often as may be necessary.

In serous meningitis a large quant.i.ty of cerebro-spinal fluid may escape, and the dressings must be changed frequently. If recovery be going to take place, the temperature gradually becomes normal and the symptoms of meningitis disappear. In involvement of the posterior fossa, the head retraction gradually diminishes and after a few days free movement is noticed. Adhesions form rapidly, binding together the surface of the brain, meninges, and the overlying bone. For this reason the drainage tubes, already inserted between the dura mater and brain, can be removed within a day or two. The exposed dura mater usually becomes covered with granulations from which a certain amount of purulent discharge may be secreted. The duration of the after-treatment depends on the extent of the operation and the size of the wound.

Eventually the skin flaps grow together and cover the brain, which afterwards may be felt pulsating through the scar. In these cases it is usually necessary to provide the patient with some protection, such as an aluminium plate.

If, however, a hernia forms and gradually increases in size, the brain should be explored again to see if another abscess can be discovered; or the lateral ventricle itself may be tapped in case of it being distended with fluid. Both these operations, however, must be looked upon as extreme measures.

If the patient otherwise recovers and a hernia still persists, the question arises what to do. Conservative treatment should first be employed, aseptic dressings being maintained, and slight pressure applied with compresses soaked in rectified spirits. If these measures fail, then the projecting portion of the hernia may be excised (see Vol.

III).

=Other methods.= In addition, the following methods of treatment have been suggested. Although many failures have occurred in proportion to the few successful cases published, yet they show the possibility that something can be done by operative measures, and that considerable advance has been made in recent years in this direction.

(i) =Repeated lumbar puncture.= In a few cases of serous meningitis this has proved successful in that it has relieved intracranial pressure. It is, however, only of value if free communication still exists between the spinal theca and subarachnoid s.p.a.ce.

(ii) =Continuous drainage from the spinal ca.n.a.l.= Friedrich, of Kiel, has suggested a counter-opening in the spinal ca.n.a.l by means of laminectomy in order to permit of drainage of the entire dural sac.

(iii) =Puncture of the lateral ventricle.= The temporo-sphenoidal lobe is pierced with a trocar, just above the zygomatic ridge, until the ventricle is reached; this has been performed frequently in order to relieve intracranial pressure. I know of only one recorded instance in which recovery has taken place in spite of there being pyogenic infection of the lateral ventricle; a fact which was proved by tapping the ventricle and removing from it a drachm and a half of purulent fluid (_Archives of Otology_, vol. x.x.xv, p. 535).

(iv) =Drainage through the internal ear.= West and Scott have recently described a case of meningitis which occurred after having curetted the inner wall of the tympanic cavity. They then opened up the labyrinth and inserted a wire drain through the internal auditory meatus, at the same time making a counter-opening in the lumbar region, through which they drained the spinal ca.n.a.l. The patient, a child, ultimately recovered.

=Prognosis and after-results.= Unless saved by operation, meningitis is almost uniformly fatal. Even if the patient recovers, whether as the result of operation or not, deaf-mutism or mental deficiency frequently occurs. In a few cases, however, complete recovery has taken place.

CHAPTER IX

OPERATIONS FOR LATERAL SINUS THROMBOSIS OF Ot.i.tIC ORIGIN

GENERAL CONSIDERATIONS

The sigmoid portion of the lateral sinus is the part usually infected.

Thrombosis, however, may occur primarily in the region of the jugular bulb from direct extension of the pyogenic infection through the floor of the tympanic cavity; this, though less frequent than involvement of the sigmoid sinus, is not so rare as has. .h.i.therto been supposed.

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:--