More than a third of all cases originate from this source (Pitt). Cerebral ab scess is far more common from chronic than from acute suppurative disease of the ear. This fact has been established beyond question by an analytical study of several thousand cases (Jansen).
it was formerly admitted that the development of an °title abscess neces sarily implied a pre-existing chronic suppuration of the ear. To-day, how ever, it is known, from cases observed during the recent epidemics of influenza, that cerebral abscess may develop after an aeute suppuration of the ear. Mon nier (La Presse AIM., Nov. 6, '95).
More than one-lialf of all cases orig inate from aural disease. The statistics of ;Jansen, who found, in an aural elinic in Berlin, abscess only in the proportion of 1 case to 2650 cases of acute otitis, and 1 to 400 of chronic suppurative otitis, are misleading. Abscess is twice as frequent in adults as in children. As to Hessler's statement that three-fourths of all fatal cases of otitis present puru lent pachymeningitis, it is found that in less than one-fourth of these cases is there any direct communication apparent between the tympanum and the extra dural abscess, microbic migration having taken place through microscopic avenues. Taking 119 eases of true encephalic ab scess, analysis shows, with reference to localization. S2 in the middle lobe, 24 in the cerebellum, 4 in both cerebrum arid cerebellum, 3 in the pans, 2 in the occipital lobe, and 1 each in the frontal lobe and cerebellar peduncle. Cerebellar abseess is more frequent in adults than in children, in whom the location is ahnost exclusively in the temporo-sphenoidal lobe. Picque and Ferrier (Annales des Mal. de l'Oreille du Larynx, du Nez, etc., Dec., '92).
Statistics upon cerebral abscess follow ing disease of the ear based on 100 eases personally observed, 91 being examined after death; in 9 the abscess was opened during life. The frequency of such ab scesses in the cerebrum is nearly twice as great as in the cerebellum; in chil dren below ten years of age their fre quency is three thnes that of adults, this difference being, perhaps, the greater distance of the tympaumn from the cere bellum in children. The liability of males is twice that of females, and the generally admitted fact of the disease being more common on the right than on the left side is borne out by statistics.
As regards the extension to the brain from the diseased temporal bone, (1) the cerebral abscess most often occurs where the (tura is implicated, in cases of dis ease of the petrous, or mastoid; (2) the dura, and brain-substance between the diseased bone and the abscess are gener ally diseased; in only 6 out of 90 cases WaS the intermediate brain-substance normal. More careful observation may
show More cases of direct extension of the suppuration from the diseased bone than is now thought to be the case. Otto Korner (Archiv f. Olirenheilkunde, vol. xxix, '90).
Next most common cause of brain abscess is trauma of the face or skull. Practically all cases occurring in yery young children are due to one of these two causes.
Study of 32 eases, 13 of which were in children under one year of age. 9 of these being under six months and 5 un der three months; 3 occurred during the second year, and 5 each in the third, fourth, and sixth years, no case being included in which the patient was five years old or over.
Conclusions; 1. Abscess of the brain in children under five years is rare.
2. The principal causes are otitis and tramnatism.
3. It rarely follows acute otitis, but most often neglected cases, and is usually secondary to disease of the petrol"; bone.
4. In the cases occurring in infancy without evident cause, the source of in fection is probably the ears, even though there is no discharge.
5. The development of abscess after in jury to the head without fracture of the skull is extremely rare. ln nearly all the traumatic cases definite cerebral symptoms shows themselves within the first two weeks after the injury. In cases with falls as remote as several months, there is probably some other cause, such as a latent otitis. L. E. llolt (Archives of Pediatrics, Mar., '98).
Among adults surgical diseases of the ethmoid bone, the orbit, the antrum, necrosis of the maxillary bones and sometimes caries of the teeth, disease of the frontal sinus, and pyogenic affec tions of the nose and throat are occa sional sources of intracranial pus-infec tion. Several cases have occurred as complications in erysipelas of the face or scalp. Suppurative adenitis of the cervical glands is another well-known source of infection. Pus-accumulations anywhere in the system—even in remote localities, as the liver, the lungs, the Fallopian tubes, etc.—may, by circula tory metastasis, be attended with a com plicating cerebral abscess.