HYDROCEPHALUS ACQUISITUS. 275 



advised. When the pain in the head is unusually severe, we may or- 

 der local abstraction of blood and cold-compresses or derivatives to 

 the nape of the neck. If these fail, we should not be too timid about 

 giving narcotics, and particularly small doses of morphia. When there 

 is the slightest suspicion of syphiloma of the brain, instead of this 

 symptomatic treatment, we should institute an energetic antisyphilitic 

 course. It is unpractical to delay this treatment, or to neglect it al- 

 together, if the syphilitic nature of the disease be not accurately deter- 

 mined. Experience teaches that even very severe structural changes 

 are capable of recovery, and often disappear under proper treatment, 

 and, on the other hand, that treatment is powerless against carcinoma, 

 sarcoma, etc. Hence, we risk little and may gain much, if, on the mere 

 suspicion of syphiloma of the brain, we treat the patient as if there 

 was no doubt about the diagnosis. 



CHAPTER XIV. 



SEEOUS EFFUSIONS IN THE MATTJKE SKULL HYDKOCEPHALUS ACQUI- 

 SITUS. 



WE have already spoken of one form of hydrocephalus, that which 

 almost constantly complicates basilar meningitis, and, in the next 

 chapter, when treating of congenital hydrocephalus, we shall also 

 treat of the effusions occurring shortly after birth, before the sutures 

 are closed. In the present chapter we shall only consider those serous 

 effusions into the cranial cavity which occur without basilar menin- 

 gitis and after the skull has closed. 



ETIOLOGY. Serous effusions into the arachnoid sac (hydrocephalus 

 externus) are rare, and hardly ever become extensive. Effusions into 

 the subarachnoid space and ventricles and oedema of the brain are 

 more frequent. 



Hydrocephalic effusions are due partly to increased lateral pressure 

 m the vessels, partly to an abnormally slight amount of albumen in 

 the blood, partly to disturbances of nutrition, which render the walls 

 of the vessel more permeable. As one symptom of general dropsy, 

 whether dependent on disturbance of circulation or on abnormal quality 

 of the blood (morbus Brightii), the hydrocephalus rarely attains a high 

 grade, although, perhaps, some sudden deaths occurring in the dis- 

 eases inducing the dropsy are to be referred to slight effusions in the 

 ventricle and to a slight oedema of the brain. Tumors and other dis- 

 eases in the posterior cranial fossa, by compressing the venae Galeni or 

 straight sinus, and obstructing the escape of blood from the ventricle, 

 sometimes induce high grades of hydroceiDhalus. Hydrocephalus, de- 



