Children are most frequently attacked, and especially during the first year of life. The great mortality among the poorest classes has been repeatedly emphasized. It is not probable that poverty and unsan itary surroundings reduce the vital resistance, but certainly the condi tions for dissemination are more favorable. Perhaps the germs are carried by domestic animals; in which purulent cerebrospinal meningitis has been demonstrated repeatedly, and also by vermin.
pathologic changes caused by the meningococcus were first systematically studied by Klebs and later so thoroughly investi gated by Striimpell, Albrecht and Ghon and others, that the subsequent investigations have made no important alterations or additions.
More frequently than in other forms of meningitis, an unequal distribution of the purulent exudate in the form of flakes and bands is found at various parts of the cerebral cortex,—especially over the parietal and occipital lobes and the cerebellum. The pia mate); lying between the purulent areas is always slightly axlematous, and this cedematous fluid contains meningococci. If the pyogenic process involves the whole surface of the brain or, as not infrequently occurs, if it is markedly devel oped only at the base, the disease does not in any way differ macroscopi cally from meningitis of other etiology.
The intensity of the pyogenic process varies greatly if the cases run very rapid courses. After scarcely one day's sickness the purulent pro cess may already be very decided, so that the entire surface of the. brain is covered by a creamy, greenish yellow pus; but, on the other hand, the purulent process may be exceeded by the saturation and hypersemia of the meninges, which as we have noted occurs not infrequently also in other fulminating forms of meningitis. Thus SOrensen reports a case, which terminated fatally on the fourth day of the attack, in which the autopsy showed only hypersernia of the meninges, especially of the spinal dura. After a longer period of sickness, the exudate which at first 1V2IS viscid, becomes stickier, firmer and may indeed have a consistence which calls to mind a thick slimy secretion. The flaky or bandlike distribution then appears very striking.
In the further course, if after weeks or months duration of the gradually recovering local disease, death occurs on account of complica tions or marasmus, one finds in the meshes of the pia only trifling remains of the amorphous exudate which has again become softer and more liquid.
The traces of the former pyogenic process may be recognized in local opacities and thickenings. But it is probable that gradually even these changes entirely disappear: at any rate we saw a caee in the Breslau Children's Hospital in which, death having occurred from intereurrent disease months after recovery from a protracted meningococcus menin gitis, tbe autopsy showed only an opaque area the size of a half dollar remaining on one parietal lobe.
If after the departure of the acute inflammatory process there remains pronounced and extensive thickening of the meninges, then gradual contractions of this scar tissue and obliteration of the important communications of the cerebrospinal canal are said to occur. Especially closure of the foramen of Magendi originating thus, is often described as the cause which leads to chronic hydrocephalus months after recovery f fora meningitis.
The changes in the spinal meninges are entirely analogous to the cerebral changes. In fresh cases thick accumulations of pus, especially on the posterior surface of the lumbar cord rarely fail. Also in protracted cases we find these in the form of flakes and bands at ail possible parts of the spinal meninges. The participation of the spinal meninges in the pathologic and clinical pictures of meningococcus meningitis, regular and considerable as compared with other meningeal infections—has, as already remarked, led to its classification as cerebrospinal meningitis.
The chorioid plexus and the ventricular ependyma regularly partici pate in the meningeal affection. Less frequently eneephalitic foci of hmmorrhagic-purulent nature are found. They may be situated as well in the cortex as in t he medullary substance and through advanced dis integration cause multiple abscesses of the brain t8triimpell).
Characteristic changes of the internal organs do not occur or are caused by the extreme emaciation due to the protracted course.