E. Encephalitis.
—The etiology of this condition is practically that of leptomeningitis. It may proceed from sinus phlebitis or from the veins emptying into the sinus, infection travelling backward rather than forward. In many cases the primary infection occurs from without, as in gunshot fractures. It is also transmitted along the lymphatic channels, since I have operated on abscess in the frontal lobe following intranasal operation. It assumes practically always the suppurative type, and may run either an acute or a chronic course. When acute the lesion is usually limited in area, and the result is an acute abscess with irregular boundaries. It may be distinguished from uremic coma by examination of the blood (leukocytosis) as well as that of the urine.
OPERATIVE TREATMENT OF INTRACRANIAL SUPPURATIONS.
In dealing with pus the surgeon can never follow a safer rule than to go according to this dictum: i. e., that pus left alone is a greater source of danger than the surgeon’s knife judiciously used. Consequently ubi pus, ibi evacua, applies to intracranial collections as well as others. For its detection and evacuation operations are now regarded as not merely justifiable, but indicated whenever there is presumption of its presence. Discussion now hinges entirely upon the wisdom of exploration when absolutely no diagnosis can be made. Save where an opening already exists, trephining is a necessary preliminary. Among other indications is spontaneous escape of pus through a previous opening or any of the natural outlets of the cranium, with or without localizing phenomena. Further indications are those pertaining to the bone—i. e., loosening of pericranium; or to the scalp—i. e., edema, puffy tumor, etc.; and certain other indications are those of a more general character, chills and pyrexia. When the dura is exposed much can be determined by the existing brain tension, it being now well established that brain pulsation is often intensified by the presence of pus beneath the dura. The most feasible method for detection of subdural or deep collections is the use of the aspirating needle—a method now generally in vogue and everywhere accepted.
MASTOID DISEASE AND THE MASTOID OPERATION.
In all cases of infection and suppuration of the middle ear the adjoining portions of the cellular structure of the mastoid undoubtedly participate. Fortunately morbid activity is usually so limited that the clinical evidences of what is called mastoiditis occur in a relatively small proportion of cases, but otitis media purulenta is so common that mastoiditis is consequently a complication of sufficient frequency, and occasionally of such severity, that it is as likely to come under the supervision of the general surgeon as that of the specialist. Moreover, the region affected is such common ground, as it were, between the broad field of the former and the restricted field of the latter that it seems to me that every general surgeon or student of general surgery should be familiar with the condition and its surgical treatment.
Several of the specific germs, of diseases like pneumonia, la grippe, etc., are known to set up acute mischief within the tympanum as well as the commonly known pyogenic organisms. They have easy access to the middle ear through the Eustachian tube, as well as by the deeper blood and lymph channels. The nasopharynx is never free from the presence of organisms, while the specific fevers, like scarlatina, and notably such infections as diphtheria, predispose to germ activity in the region into which the inner end of the Eustachian tube opens. The Schneiderian membrane, which is practically continuous from the ethmoid cells to the membrana tympani, affords easy travelling, and in all directions, for infecting organisms. The violence of reaction will depend upon two uncertain and indeterminable factors, the virulence of the organism and the susceptibility of the patient. To what extent the mastoid cells and antrum, around an infected tympanum, shall participate may be, to a considerable degree, a matter of their anatomical arrangement. When, however, they do participate to any great extent the fact is made known by symptoms of unmistakable character. These constitute the added features of what is known as mastoiditis.
The cavity in the mastoid known as the mastoid antrum, no matter what may be the arrangement of the other cells, is always present, and in the presence of deep disease the antrum should be first opened. In close proximity to the antrum are cavities like the sigmoid sinus, the horizontal semicircular canal, the facial canal, and the interior of the cranium. While opening the antrum care should be taken to avoid encroachment upon the other cavities or structures, except in those instances where there is evidence of intracranial mischief, in which case it may be desirous to expose the sinus wall, or even a considerable area of brain surface. The mastoid prominence varies in different individuals, extending outward to accommodate the sigmoid groove for the lateral sinus.
According to the intensity of the process the pathological condition of the mastoid may vary between an empyema of its cavities, an osteomyelitis of its osseous structure, or osteoperiostitis of its external surface. Nevertheless all three of these may be combined in the same case.