Secondary Factors in the Causation of Coma.—There are, of course, various other influences that affect this result. The person's susceptibility is one; car bonic-acid poisoning due to superficial respiration is another. But most im portant of these is the rapidity with which the effusion occurs. On the ex perimental side it is well known that the effect on consciousness depends somewhat on the rapidity with which the compression is produced. But it is rare in clinical work to meet cases where a hemorrhage has taken place with any such rapidity as in the average experi ment. As Liddel long ago pointed out, considerable time is taken up before the bleeding stops. We also know that in the slow, ingraveseent form, though a day or two elapse in the process, coma just as certainly supervenes when. the volume of the focus becomes adequate.
The disappearance of coma is attrib uted to a re-establishment of the cir culatory balance, to reduction of press ure from lessened cerebrospinal fluid, and perhaps a gradual tolerance to the focus. The shock-effect passes off, and some of the fluid of the focus is ab sorbed.
symptom, of itself and without corroborative manifestation, is rarely indicative of cerebral hamor rhage. A considerable majority of all cases of aphasia are due to other causes (see article on APHASIA, VOL i). These are mostly transient forms lasting from a few hours to a few days and embracing all degrees of speech-impairment up to its complete lass. They are occasioned by gout, urminia, and less frequently other toxic conditions. Possibly the standard writers do not take sufficient notice of these transient forms. Even of the more lasting cases a certain num ber will be due to thrombosis, embolism, etc.
Only in a part of the cases of cerebral limmorrhage do aphasic symptoms ap pear. To produce these the speech-tract must either be directly injured by the effusion or indirectly implicated by pressure. This, of course, only occurs when, in rig.ht-handed persons, the lesion is on the left hemisphere, and in left handed in the right hemisphere. Ap parent exceptions to this rule occur as in a recent case (of embolism) where an originally-left-handed youth had so trained himself that he passed for a right-handed person.
All degrees and forms of aphasia oc cur in association with hmmorrhagic apoplexy'. Where it is due to implica tion and not to direct involvement of the speech-centre or tract, then recovery from this symptom may occur, the time required and the extent of recovery be ing dependent on the circumstances of the case. By speech-centre we, of course,
mean not only the motor centre in Broca's convolution, but also the hear ing-centre and other associated parts. Inasmuch as all forms of aphasia and paraphasia are involved, it is not prac ticable to enter on a discussion of them here.
Convulsions, Twitchings, etc.—Rarely a few spasmodic twitches occur during the onset-period in the territory where paralysis is developing. These may not be noticed unless in the face. It is not certain that they' point to a cortical focus.
Quite distinct from these are the uni lateral clonic convulsions (Jacksonian type) that occur in the rare cases of effusion about the cortical motor area. Such cases are far oftener of traumatic than of spontaneous origin.
Of course, urremic convulsions may bring on or accompany an apoplectic seizure, though this is unusual. Other wise general convulsions in this condi tion point strongly to ventricular heem orrhage or to rupture into the lateral ventricles.
[They also are not rare in thrombosk, and in both meningeal and frontal haemorrhages. W. BROWNING.] Even in case of such rupture, how ever, convulsions clo not always follow; nor does slight oozing, as in many cases of impending rupture, have this effect. When such convulsions do occur, they may- be of the severest character that we ever witness. In any case, such com plications give a very bad outlook, for ventricular rupture is only more cer tainly and rapidly fatal than un-emia. Rigidity of the paralyzed or even both sides is also frequent in ventricular rupture.
Paralysis ; Respiratory Paresis.—This is one of the commonest as well as most striking and characteristic symptoms, although not a necessary accompani ment. It may affect either motion or sensation or both.
Tbe time of the attack at which it develops depends on the location and the rapidity of development of the effusion. Usually it appears with the onset of the seizure, though at first frequently but a mild degree of paresis; in such a case we can conclude that, as yet, the motor path is only suffering from pressure. In occasional cases the paralysis is not man ifest until later or becomes pronounced only in the reaction-stage; but it is then difficult to distinguish from an increas ing effusion.