240 DISEASES OF THE BRAIN 



Diagnosis. — ^The diagnosis depends upon the history of 

 some infection, the symptoms of rapidly increasing dis- 

 turbance in consciousness, the eye symptoms (pupils of 

 unequal size, strabismus, nystagmus, congestion of the 

 papilla), trismus, and sensitiveness of the poll. Where 

 these symptoms are vague the diagnosis is extremely 

 difficult. 



From the standpoint of differential diagnosis the following 

 conditions must be taken into consideration: 



(a) Functional disturbances of the brain such as accom- 

 pany acute, feverish, infectious diseases. These are accom- 

 panied by mental depression, disturbance in consciousness, 

 etc. The diagnosis here would depend upon the evidence 

 of the existence of the primary disease, and the fact that the 

 brain symptoms are not as well developed as in meningo- 

 encephalitis. 



Meningo-encephalitis might be confused with rabies. In 

 rabies, however, consciousness is not disturbed in the begin- 

 ning, the clinical symptoms develop progressively and char- 

 acteristically (melancholia, frenzy, paralysis), and forced 

 movements and spasms fail. Acute encephalitis could only 

 be excluded in cases where topical symptoms appear early 

 (hemiplegia, ataxia, monoplegia, etc.). A tubercular men- 

 ingitis could only be diagnosed by discovering a tubercular 

 iritis (rare), the evidence of tuberculosis in other organs and 

 the tuberculin test. 



(b) Poisonings (lead, merciu-y, brine, santonin, tobacco, 

 poppy leaves, opium, etc.) also produce fuiictional brain 

 disturbances which resemble the symptoms of meningo- 

 encephalitis. Usually the history coupled with the fact 

 that the patients show at the same time gastro-intestinal 

 symptoms suffice for the diagnosis. Brain disturbance is 

 also noted in some cases of helminthiasis and in forage 

 poisoning. 



Prognosis. — Except in the puerperal form in cows, which 

 often reacts favorably to proper treatment applied early, 

 meningo-encephalitis is a very fatal disease. The mortality 

 is over 75 per cent. In the horse those cases which do 

 recover are left "dummies" from consequent hydrocephalus. 



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