HAEMATOMA OF THE DURA MATER. 231 



arachnoid space, we usually find it as a more or less thick layer spread 

 over the surface of the cerebrum and cerebellum. If the arachnoid be 

 not torn, of course we cannot wash off the extravasation by turning a 

 stream of water on it. Usually part of the extravasation reaches the 

 ventricles, and there also we find more or less blood. In haemorrhages 

 between the dura mater and arachnoid the extravasation is generally 

 collected, more particularly on the tentorium and at the base of the 

 skull, and thence extends into the vertebral canal. But on the con- 

 vexity of the hemispheres we also find bloody masses, which may be 

 washed off by squeezing out the sponge over them. In both forms of 

 haemorrhage there is either simply flattening of the convolutions and 

 anaemia of the brain-substance, or else the layers of brain-substance 

 next to the haemorrhage are suffused with blood and softened. 



Haematoma of the dura mater is usually located near the sagittal 

 suture and has the form of an oval flat sac, which may attain consid- 

 erable size, and may be four or five inches long, two or three broad, 

 and half an inch thick. The walls of the sac are colored rusty-brown 

 by altered haematin ; its contents are partly fresh fluid or coagulated 

 blood, partly dirty reddish-brown clots, that are unmistakably older. 

 The corresponding half of the cerebrum is flattened, or even shows a 

 depression. Not unfrequently the haematoma is on both sides. We 

 have the opportunity, rather frequently, of observing the commence- 

 ment of a pachymeningitis haemorrhagica ; for, in many autopsies, we 

 find a delicate yellow or brown connective tissue, larger on the inner 

 surface of the dura mater and firmly adherent to its surface. 



SYMPTOMS AND COUESE. Haemorrhages in the subarachnoid space 

 or on the free surface of the arachnoid, do not belong to the " local " 

 but to the " diffuse " diseases of the brain. Hence, when there is no 

 complication with cerebral haemorrhage, they are not accompanied by 

 the regional symptoms characteristic of this, especially hemiplegia; 

 on the other hand, the apoplectic fit is usually uncommonly severe, as 

 the bleeding is generally very abundant, and is spread over both sides. 

 Frequently the apoplectic fit occurs suddenly without any premonitory 

 symptoms, and the patients die with the above-described symptoms of 

 apoplexie foudroyante. When this occurs, we can, at most, make only 

 a probable diagnosis, which depends solely on the absence of hemi- 

 plegia, the symptoms of which may, as a rule, be distinguished, even 

 in the severest fits, from cerebral haemorrhage. In other cases the 

 apoplectic stroke is preceded by severe headache, and in some cases 

 by general convulsions. Since these symptoms, particularly the latter, 

 only occur exceptionally in cerebral haemorrhage, and are often seen 

 in extensive disease at the convexity of the hemisphere, they, in con- 

 nection with the absence of all signs of hemiplegia, enable us to decide 

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