236 DISEASES OF THE BRAIN. 



(which G-riesinger calls a phlegmasia alba dolens en miniature) may 

 arise from other causes than from the extension of the thrombus 

 through the emissaria santorini which pass out in the sigmoid fossa. 

 In most cases it is only from the occurrence of rigors and the signs of 

 metastatic deposits in the lungs that we can conclude that caries of 

 the petrous bone has not only induced meningitis and encephalitis, 

 but has also led to thrombosis in the cerebral sinuses. 



TREATMENT. On the signs, or even suspicion, of inflammation of 

 the dura mater, we should use energetic antiphlogistic treatment by 

 repeated application of leeches behind the ears. At the same time, if 

 there be any otorrhcea, we should make warm injections into the af- 

 fected ear and cover it with cataplasms. Active purges and large 

 blisters to the back of the neck are also useful. In other respects, the 

 treatment of pachymeningitis corresponds with that >f inflammation 

 of the pia mater. 



CHAPTER VIII. 



INFLAMMATION OP THE PIA MATER, WITH PTJRO-FIBRINOTJS EXUDA- 

 TION MENINGITIS OF THE CONVEXITY MENINGITIS SIMPLEX. 



ETIOLOGY. In acute meningitis, an exudation containing many 

 pus-cells is effused into the subarachnoid space ; in chronic meningitis 

 there are diffuse cloudiness and thickening of the pia mater and arach- 

 noid, from proliferation of the connective tissue. 



Acute meningitis, with puro-fibrinous exudation, is in many cases a 

 secondary disease, and as such accompanies injuries and diseases of 

 the skull and of the dura mater or other inflammations and other dis- 

 eases of the brain. Except in the epidemic form, of which we shall 

 speak in Chapter IX., it rarely occurs as an independent disease in pre- 

 viously healthy persons, but is somewhat more frequent in cachectic 

 individuals or in those exhausted by long illness. Thus it is observed 

 in convalescence from pneumonia and pleurisy, or from acute exanthe- 

 mata and other infectious diseases, and from protracted diarrhoeas, but 

 especially during Bright s disease, etc. Although in these cases we 

 frequently cannot discover any new source of injury acting on the 

 body, we have no right to consider this inflammation of the pia mater 

 as metastatic or even as secondary. The action of the sun's rays or 

 of a very high or even of a very low temperature on the head, chilling 

 the body, or getting wet, misuse of liquor, etc., are mentioned among 

 the exciting causes of meningitis. But only the last of these causes 

 has been proved to have any influence in exciting this disease. Re- 

 cently Grriesinger has called attention to a form of meningitis which 



