The most interesting fact elicited by this examination is that there were only six of forty-eight cases with regard to whom the origin of epilepsy was altogether inexplicable; and of these six it must be added that in two of the males there was some doubt as to the presence or absence of "exciting cause." Of forty-six epileptic individuals, therefore, there were but two in whom the commencement of the disease was altogether irreducible by pathologic laws. The next fact of importance is that hereditary predisposition in no one case operated alone. This would follow partly, as a corollary, from the principle already established, viz., that hereditary epilepsy is usually developed before or at the time of puberty.* The one case in which it was delayed beyond that period was a girl, æt. 19, in whom the outbreak was attributed to mental and emotional disturbance, plus some eccentric irritation. But, over and above the predisposition from inherited tendency, and the disposition of body induced by special organic developments, there were six individuals in whom some further and "exciting cause" was operative. For our present purpose, however, the most interesting fact is that there were ten persons in whom epilepsy could be ascribed only to the increased activity—preternatural in these cases we must assume which in kind constituted, and in degree exceeded, that proper to the period of life in which the disease was developed. In twelve others there were, in addition to the general metamorphic activity, some locally-disturbing "occasions" of the attacks. Further, in no less than thirtyfour of forty-eight cases can we trace the sole or conjoint influence of the cause we are now considering-viz. developmental activity of nutrition,-in the production of epilepsy. When the period of life was in itself the sole predisposition, i. e. when hereditary taint was absent, there was nothing peculiar or special in the mode or locality of action of the exciting cause. Thus, in the twelve cases forming this category, there were to be found psychical or emotional perturbations; eccentric irritations; physical influences, e. g. insolation, contusion; analogous conditions, venereal excess; and intra-uterine * See Chap. IV., Etiology, p. 129. commotion: the most frequent of these being, as might be expected from the general history of causation,* the first, viz. psychical. The predisposing influence of this condition appears, then, to be general; and this inference is further warranted from the fact already stated,† that local changes, as of menstruation, for example, have little effect upon the fits. The recurrence of attacks at a monthly period is as common in the male as in the female; it is not, therefore, the uterine or ovarian, but the general, condition which is prominently related to the disease. Further, although epilepsy has commenced in many individuals during the first and second dentition, it is only in two cases that there has been such notable local irritation from the process as to have induced the parents or friends of the patients to assign "teething" as the exciting cause of the attacks. The morbid general conditions upon which epilepsy was superinduced, viz. pneumonia and rheumatic fever, occurred in both cases without hereditary predisposition; they were both females; the sufferer from pneumonia was seven years of age, and had been highly stimulated during her convalescence from the disease; the rheumatic fever occurred in a person æt. 20. In the instance in which fright of the mother during pregnancy was the assigned cause, the attacks commenced within the first year of life. With the exception, therefore, of the case dating from rheumatic fever, there were conditions of proclivity other than those of the assigned "exciting causes." The last mode in which the medulla oblongata and the upper part of the spinal axis may become so affected as to produce epilepsy is by the operation of morbid, accidental, or experimental lesion in some portion of the nervous system. That cerebral or spinal tumour, chronic inflammation of the meninges, softening of the brain, neuromata, &c. &c., might occasion convulsions of epileptiform character, has long been known; but it has been frequently urged in this work that these cases are to be distinguished, in the majority of instances, from true epilepsy. Their clinical history differs either altogether, except in the mere existence and general form of the attack; or in part, * See p. 132. + Chap. IV., Natural History, p. 149. there being perhaps true epilepsy, but, over and above this, the phenomena of structural disease. In some cases it would appear, however, that the course during life has been that of epilepsy, but that, post mortem, some lesion is found, of the existence of which no symptoms had aroused the suspicion. These cases are, I believe, very rare; and as observation is extended and rendered habitually more minute, they will be found still more exceptional. The immediate cause of epilepsy is, as has been said, overaction of the reflective centre, from increased vascular supply, and exaggerated nutrition-change. This state may be induced by structural change:-1. In that centre. 2. In contiguous portions of the nervous system. 3. In portions, not necessarily contiguous, but functionally related. Esquirol was one of the first to draw marked attention to the existence of spinal lesions in epileptics. In nine of ten cases he found alterations in the cord or its meninges; and observations are numerous to the same effect.† It must, however, be remembered that the reflective centre is frequently found free from all such lesions. We must, therefore, regard them when present as operative only indirectly; that is, by inducing ulterior changes, which latter are the proximate conditions of the disease. This follows from the principles already laid down in the first chapter of this book.‡ But lesions may be found outside the centre of reflection, and yet within the nervous centres, such as tumours within the cranium, &c. When so situated, they may induce epileptiform seizures in one of two modes: either by their irritant effect upon afferent nerves, such as those in the meninges; or by the extension of vascular activity from them, as its centre, into the contiguous medulla oblongata. In regard of the former mode, Pflüger has shown that when a cerebral nerve is injured the tendency is for reflex excitability to travel downward, i. e. towards the medulla oblongata.§ Upon analysing a consider Traité des Maladies Mentales, Tome I., p. 311. + Vide Brown-Séquard's Researches on Epilepsy. See p. 11. § Die sensorischen Functionen des Rückenmarks der Wirbelthiere, p. 80 et seq. able number of cases, for the purposes of diagnosis, I found that "convulsions are most frequent in tumours of the cerebellum; and that they diminish in frequency as the seat of lesion advances forwards, i. e. through the posterior and middle to the anterior lobes of the cerebrum."* From this it may be inferred that the latter mode above described is the more frequently exemplified. More instructive facts, however, with regard to this portion of the pathology of epilepsy, are those furnished by the experimental researches of M. Brown-Séquard.† It has been proved beyond all question that attacks closely resembling those of epilepsy may be induced in certain mammalia by injury to the spinal cord, especially by cutting through one of its lateral halves, or by dividing the posterior columns and cornua of the grey matter; the implication of the latter being apparently essential.‡ But the attacks are not immediate results: they follow in the third or fourth week; showing that they depend upon some induced condition; and from their commencement in those parts which are innervated from the medulla oblongata, we infer that it is this portion of the nervous reflective centre in which exists the primary change of epilepsy proper. This passage upwards towards the medulla oblongata of changes commencing in the extremities and in the spinal cord was recognised long ago, but systematized especially by Pflüger.§ Brown-Séquard inferred that the medulla oblongata had its nutrition changed by paralysis of the vascular nerves; while Van der Kolk has proved by microscopic examination, showing dilatation of the capillaries,¶ that this inference is correct. Of great interest is the further fact established by BrownSéquard, viz. that with the change in the central parts there is also an alteration in the condition of some centripetal nerves, or of their peripheric expansion. The paroxysms are induced by irritation of the latter, and sometimes cured by its cauterization. The nerves undergoing these changes are the second and Diagnosis of Diseases of the Brain, &c., p. 186. + Researches on Epilepsy, &c. Op. cit., p. 4. § Die sensorischen Functionen des Rückenmarks der Wirbelthiere, p. 86. Op. cit., p. 69. On the Minute Structure and Function, &c., p. 244. third branches of the trigeminus, with the second and third cervical nerves on the same side as that to which the injury was inflicted.* Epilepsy, then, may be regarded as consisting "mostly in this increased excitability"† of the spinal axis; but when induced artificially in the manner described, not only is the centre implicated, but some afferent nerves share in the exaltation of functional activity. Hence we may understand the nature of those cases (see Cases IV. to VII.) in which the attacks are more or less closely related to peripheral changes, constituting the different forms of "aura." The latter are not essential; they are additional phenomena, induced by the nature and locality of the lesion which set up, with them, the convulsive conditions. From the earliest periods of medical history it has been known that injury done to the nervous trunks, or even to their peripheral expansions, might induce convulsions, tetanus, or epilepsy. Pflüger has, in his work already quoted, collected cases which illustrate this point. Brown-Séquard mentions the fact of an accidental bite in the foot of one of his guinea-pigs having been followed by epileptiform convulsions, which were cured by section of the sciatic nerve; § and Van der Kolk suggests, what is probably the true relation of these groups of phenomena, viz. that the "constant nervous irritation," caused by such injuries, gradually affects "in the same manner," the medulla oblongata.|| The characteristic feature of epilepsy is the occasional occurrence of loss of consciousness, with spasm; this of itself may constitute the disease. Such combination results from over-action and over-excitability of the medulla oblongata and upper part of the spinal axis: this functional change is brought about in various ways, viz. by hereditary predisposition, by violent impressions from without, by general conditions of exalted nutrition-change, by morbid or artificial lesions of the nervous centres, and by eccentric irritation: when any one of these causative conditions exist, there are some immediate as well as indirect results of their operation; such as pain, spasms, para * Brown-Séquard, op. cit., p. 6. + Op. cit., P. 35. § Brown-Séquard, op. cit., p. 30. |