It has been also considered best to omit treating of the collateral hyperæmia of the brain sometimes found with erysipelas of the face and scalp. This I regard as essentially of the same nature as the metastatic meningitis of erysipelas, if it be not in reality a first stage of the latter.
ETIOLOGY.—An individual predisposition to cerebral congestion was one of the unquestioned facts of the older medical writers. It undoubtedly exists, and to-day we attribute it to inherited vascular conditions either affecting the calibre and coats of the blood-vessels or the vigor of the vaso-motor apparatus. I have remarked the transmission of that weakness of the latter which underlies the congestive phenomena of later life much more frequently in the female than in the male sex.
It has been claimed that external refrigeration produces hyperæmia of the brain, as of other internal organs, and that this accounts for the greater frequency of the disorder in cold weather. Niemeyer indeed speaks of persons who, suffering from this condition, appear and act in such a way as to convince the laity that they are intoxicated; and Andral, Falret, and Hammond note the occurrence of a much larger number of cases in the winter than in the summer months. I apprehend that the condition described by Niemeyer must be extremely uncommon, both from individual experience and the rarity of its mention as an independently observed fact. With regard to the alleged greater frequency of the disorder in winter, it must be remembered that all the three observers cited include in their computation a number of cases in which congestion was a collateral feature; they did not limit themselves to the disorder as spoken of here. Certainly, the physician will see few if any persons who consult him because of the hyperæmia-producing effects of a cold day.
The suppression of habitual discharges, of the hemorrhoidal flux, and the cessation of menstruation are associated in many instances with the more formidable grades of cerebral hyperæmia. Many phenomena of so-called climacteric insanity depend on congestive states. The sudden closure of an old ulcer or the removal of hemorrhoids in advanced life has in some well-established instances provoked alarming seizures not unlike those noted with paretic dementia. The chain of proof establishing the direct influence of physiological and pathological discharges on the vascular controlling apparatus of the brain is most complete. Not alone cumulative clinical observation, but the occasional happy result of therapeutical procedure based on this supposed interdependence, support it. Thus, the congestive cerebral state is recovered from when the menstrual or hemorrhoidal flow is re-established, or an issue is formed in the nape of the neck, or an old ulcer is allowed to reopen.6
6 The treatment of paretic dementia, particularly of the congestive type, is also based on this relation. The irritating antimonial ointment and issues in the nape of the neck, etc. have been lauded by older observers, and in two of my own cases had the best results—in one, indeed, with established restitutio ad integrum of now nearly two years' duration. I am inclined to suppose that its abandonment is due to an improper selection of cases; in the ordinary premature senility and syphilitic types such treatment is altogether ineffective. It is applicable to but a minority of cases at best, and to them only at an early period. It is probably to a similar form of congestion that Bouchut refers when (“Les Nèvroses congestives de l'Encéphale,” Gazette des Hôpitaux, 1869) he speaks of a cerebral hyperæmia developing under the mask of a meningitis—an expression that may be allowed if understood in the same sense as the comparison between hydrocephaloid and hydrocephalus.
The origin of most cases that are brought to the physician's attention is more or less complicated. A business-man, lawyer, or student suffering from worry incident to his profession, living so irregularly as to provoke gastric disturbances, becomes afflicted with insomnia, and in addition is also constipated. Straining at stool, he finds a dull, heavy sensation affecting the upper part of his head; attempting to resume his work, this is aggravated, and after a series of temporary remissions the condition to be later described becomes continuous. In such a case the insomnia, usually due to neural irritability, if not aggravated by an existing dyspepsia, leads to such a one, and a circulus vitiosus familiar to all physicians is established. Each of the factors concerned involves strain of the cerebral vaso-motor apparatus, but none more so than the insomnia. It is not so much the intensity of the strain as its long duration and the exhaustion of the centre which in sleep is supposed to be at comparative rest. This rest is not obtained, and, in conformity to the laws of neural exhaustion, that centre becomes morbidly irritable. Now, gastric irritation is competent to produce a reflex influence on even the healthy cerebral organ; to do so it must be a severe one; but with the class of persons alluded to the slightest indiscretion in food or drink is sufficient to set up reflex vertigo or headache. The current theory regarding these symptoms is that they are due to stimulation of the vaso-constrictors and ensuing cerebral anæmia; but the subjects before us will usually be found to flush up instead of becoming pale, as in simple vertigo a stomacho læso, or if there be initial paleness, there is a secondary flush, as if the tired arterial muscle had become exhausted by the effort at obeying the reflex stimulus. In addition, a profuse perspiration sometimes breaks out on the upper part of the body.
The influence of traumatic causes and insolation in producing a tendency to repeated and severe cerebral congestion is recognized, particularly among alienists. It is supposed that an abnormal irritability of the vaso-motor apparatus is provoked by these causes. Abundant evidences are sometimes found in the brains of such persons of an altered state of nutrition of the brain and its membranes, and which point in the direction of congestion.
In the conditions thus far alluded to it can be fairly assumed that the determination of blood to the cerebral blood-vessels is more or less active. Passive congestion due to impeded return circulation is of secondary interest, as the primary disease, be it a pertussis or a laryngeal, cardiac, pulmonary, or surgical condition, will constitute the main object of recognition and management. Certain quasi-physiological acts, as coughing, hurried breathing, holding the breath while straining at stool, and placing the head in a dependent position while acting in the direction of passive hyperæmia, are to be considered in connection with the active forms of congestion which they may momentarily aggravate.
MORBID ANATOMY.—Owing to the non-fatality of the commoner forms of cerebral hyperæmia, no pathological observations of them are at our disposal, nor can we assume from analogy that the appearances would be well marked if they could be made. What little knowledge we have is derived from a study of more serious conditions of which cerebral hyperæmia is an initial, collateral, or episodial feature.
In pronounced cerebral hyperæmia the entire brain is, as it were, tumefied, so that the dura appears tensely stretched over its surface and the gyri are flattened; both the meningeal vessels proper and those of the pia are injected. According as the hyperæmia is active or passive the color of this injection varies, being of a brighter red in the former, of a purple or bluish color in the latter case. The purest instances of active cerebral hyperæmia which I have seen were found in patients dying in the apoplectiform phases of paretic dementia (progressive paralysis of the insane). Here the cortex on section exhibited a beautiful rosy tint, which was distributed in darker and lighter strata in correspondence with the distributional areas of the short and the long cortical arteries; there were numerous puncta vasculosa both in the cortex and in the white substance, and in some instances the arachnoid or the ventricular fluid was tinged with blood, albeit no vascular rupture could be discovered. The red blood-corpuscles undoubtedly escape by diapedesis from the surface as well as the endymal vessels; the same thing occurs in the intracerebral blood-vessels, whose adventitial spaces are often crowded with accumulations of red blood-discs, while groups or single ones are found scattered in the surrounding parenchyma, and even in the periganglionic spaces. Occasionally accumulations of pigment found near the vascular channels remain to attest the former existence of other hyperæmias, and indeed slight accumulations of this kind are found in the brains of most persons who have reached adult life. These are to be regarded as remnants of the physiological hyperæmias to which all active individuals are subject. It is only when the accumulations become considerable and numerous, as in the chronic insane, or are associated with those changes in the blood-vessels which are discussed in the articles on thrombotic and hemorrhagic cerebral disease, that they can be regarded as indications of a pathological condition.