244 DISEASES OF THE BRAIN 



Etiology. — ^The most common cause of abscess of the 

 brain is strangles, which assumes the irregular form and 

 leads to internal metastatic abscesses. It may occasionally 

 result from other infectious diseases, such as puerperal sep- 

 ticemia, purulent pneumonia, infectious pneumonia (with 

 secondary pus infection) and pyemia. Occasionally an 

 abscess of the brain may result from direct injury to the 

 cranium or from abscesses which occur in the neighborhood 

 of the brain. In rarer instances parasites (estrus, coenurus, 

 echinococcus in sheep; Estrus bo vis in cattle, and gastrophilus 

 in the horse) are causes. 



S3nnptoms. — The symptoms of brain abscess may develop 

 either very rapidly or gradually. In the former case the 

 symptoms are acute; in the latter subacute. When the 

 symptoms develop rapidly the patient shows fever and not 

 infrequently mental excitement, even amounting to rabi- 

 form symptoms. These may be followed by mental depres- 

 sion or may persist until the death of the animal. The 

 muscles may twitch or undergo clonic spasms; forced move- 

 ments are not infrequently observed. The patient usually 

 dies in a few days or in less than two weeks. In other 

 instances, as noted, the symptoms develop gradually, the 

 patient showing disturbance in consciousness, forced move- 

 ments, usually walking in a circle. There may be occa- 

 sional manifestations of cerebral excitement; epileptiform 

 attacks with intervals between during which the patient 

 appears normal. The temperature may not be increased, 

 although usually it is intermittent or remittent in type 

 (pus temperature). Topical symptoms, such as sudden 

 blindness in one or both eyes; the pupils may react unsym- 

 metrically. Hemiplegia has also been observed. The head 

 of the patient is often held to one side and attempts to 

 straighten it cause symptoms of excitement. Some patients 

 show vertigo, irregular gait, and a tendency to fall while in 

 motion. Sometimes pressure on the poll produces epilepti- 

 form convulsions. 



^, Diagnosis. — ^The diagnosis depends very largely upon the 

 history of the case, i. e., whether or not the patient has 

 suffered from a disease of suppurative character (strangles, 



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