There are no statistics in regard to the frequency of encephalitis in ehildren. If w-e leave out other rarer causes, such as sinus thrombosis, and attribute cases of cerebral infantile palsies beginning with acute febrile brain symptoms to encephalitis, we must conclude that the dis ease, as well as poliomyelitis, is quite frequent in childhood and in the majority of cases ends in recovery.
For the pathology of these forms of encephalitis we depend in part on post-mortem findings in infants. and adults, and in part on cases that have ended in recovery and have come to autopsy later, because very few post-mortem observations have been made in older children.
Acute circumscribed inflammation of the brain in its typical form is a litemorrhagic encephalitis exhibiting one or several inflammatory foci with the characteristic histologic findings. In less recent cases this red softening is replaced by so called yellow softening, in which the foci present a necrotic appearance and contain many degenerated tis sue elements, with less marked engorgement of the blood vessels. The termination of encephalitis in abscess, cysts, sclerosis and porencephaly, will form the subject of a later chapter (brain abscess, diffuse sclerosis, infantile palsy). Bacteria, such as the influenza bacillus and the men ingococcus, have repeatedly been found in encephalitic foci. The seat of aeute encephalitis may be in the cerebral substance, in the basal ganglia, in the ventricular region or in the medulla oblongata, and the clinical pictures produced vary in accordance with the distribution.
Symptomatology.—Acute encephalitis of the cerebrum may mani fest itself in a variety of ways. In a certain proportion of the cases it is characterized hy severe brain symptoms and high fever. The child is extremely ill and may lie motionless for hours or days as if life were already extinct; there may be tetanic spasms and general convulsions, rigidity of the neck, opisthotonos, hyperpyrexia up to 41° C. (105.S° F.). The relatives usually state that the disease has been diagnosed menin gitis and that a fatal prognosis has been given. Nevertheless, an at tentive observer will note even in a case of this kind, certain symptoms pointing to a localized disease of the brain. There may be tremor of
one or both extremities on one side; facial palsy, monoplegia in one extremity, aphasia or sensory disturbances frequently develop sud denly. The eyes are often in a position of permanent convergence, the eyeballs directed upward; after a certain time conjugate deviation ensues ("the patient looks at the disease focus"). Optic neuritis is not infrequently present. The child continues in this condition for a few days or a week. lf, to the great astonishment of the relatives, the child survives, paralytic symptoms usually remain which gradually give the disease the character of a cerebral infantile palsy. Unilateral or general convulsions or idiocy may also remain as the result of the encephalitis.
The course of infantile encephalitis is not always as violent as has just been described. Sometimes the fever is moderate; vomiting, headache, and rigidity of the neck are overshadowed by- the irritative and paralytic phenomena in the extremities and in the cranial nerves. The ineonstancy of the symptoms and frequency of localized and general tremors are quite characteristie of these subacute forms of encephalitis.
Finally there are cases with an insidious course, presenting a symp tom-complex which resembles that of brain tumor. Oppenheim has called attention to cases of this kind, which are usually- regarded as cases of brain tumor until the favorable outcome casts a doubt on the diagnosis. Of course, the diagnosis of encephalitis in a ease of this kind must be tentative; but we practically know of no other slowly progressive morbid processes in the brain that end in sttch complete recovery as inflammatory, or at least vascular disturbances. Recovery may be complete, or local and general cerebral symptoms may persist. in a case under my own observation in which there had been bilateral paralysis of the abilucens and choked disc, permanent epilepsy resulted, and it is conceivable tliat a circumscribed inflammation in a silent region of the brain might end in recovery and leave the patient an epileptic. It is pos.sible that cases of acute neuritis ending in recovery with neuritic atrophy also belong to this category.