OPERATIONS FOR MENINGITIS OF OTITIC ORIGIN
Formerly the onset of symptoms of meningitis was a distinct contra-indication to operation. More recently, however, this view has become modified, especially as it has been shown definitely by Macewen, Jansen, Brieger, and others that recovery is possible if operation is undertaken sufficiently early before the inflammation of the cerebral membrane has become diffuse.
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 space, or the ventricles, the hypersecretion being probably caused, as Merkens suggests (Deutsche Zeitsch. für 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.