(From water, and the head). Dropsy of the head. This disease has been divided into two species, external and internal. In the first, water is confined between the skull and the integuments. In the second, the fluid is within the cranium, between it and the brain; between the membranes; or distending the ventricles. Dr. Cullen places the hydrocephalus externus, including those cases where the fluid is between the skull and the dura mater, as a genus in the class cachexia, and order intu-mescentie, which he defines a soft, inelastic, intumescence of the head, with the sutures of the cranium gaping. This complaint is so obvious, that it requires not any description for its discovery. In general, it is necessary to establish some drain from the head by a continued blister from the neck; free copious evacuations by stool must be procured; and we think the cure expedited by a grain of calomel every night. This medicine seems to give tone and energy to the circulation, which, in this disease, is apparently deficient. With the same view, after the vessels of the head are emptied, the bark, with cold bathing, is highly useful; and even when the head has been peculiarly large this plan has succeeded. See London Medical Observations, vol. v. p. 13; Medical Transactions, vol. ii. p. 18; Edinburgh Medical Essays, vol. ii. p. 22.

The hydrocephalus internus is placed as a species of apoplexia hydrocephalica in Dr. Cullen's system. In a nosological work, he remarks, it is difficult to arrange accurately diseases which assume in their course different appearances; but he prefers placing this disease under the title apoplexy, because the tumour is not evident to the senses; and because it greatly differs in its symptoms from the external hydrocephalus, which is clearly perceptible. In its proximate cause, also, and at length in its symptoms, it is nearly allied to apoplexy. Dr. Fothergill names the internal hydrocephalus the dropsy of the ventricles of the brain, for the ventricles are the proper seat of the disease. Dr. Macbride names it the febris hydrocephalica; others cataphora hydrocephalica.

The internal hydrocephalus arises gradually, affecting

H Y D 7 70 H Y D chiefly infants of a fair light complexion from the early months to about the age often. Between seven and ten the disease is rare. The first symptoms are irregular fever, with symptoms of considerable irritation of the bowels, so as to induce a suspicion of worms. The discharges from the bowels are procured with difficulty; the urine is often scanty. In general an obstinate costiveness gives the first symptoms of alarm; but the complaint still proceeds so insidiously, that the most cautious observer can scarcely fix on any appearance to justify alarming the parents. Sometimes slight wandering pains about the nape of the neck or the upper extremities precede, and are considered as febrile. When the disease appears in a more pointed form, a violent pain, deep seated in the head, seems to extend from temple to temple, and across the forehead; sickness is at times considerable; the patient occasionally doses and sighs; the breathing is interrupted; the pulse unusually slow, often irregular; at times the sleep is apparently sweet and easy, but in general disturbed, and interrupted occasionally by a violent scream, often a pathognomonic symptom of the disease. The pupil of the eye is dilated, and scarcely contracts, even by a strong light. The eye itself is often turned upward; but more commonly contracted by a spasm, which occasions squinting. A little before death's approach, feverishness sometimes attends, especially towards evening; at last the pulse quickens, the breathing is very laborious and difficult; the heat excessive; the patient is averse to the light, takes things greedily, and cannot bear any but an horizontal posture; the excrements are insensibly voided; the hands are commonly kept about the head; the eye lids become paralytic, and the iris immoveable; a great heat and sweat spread all over the body; the pulse trembles, and strength soon fails, if a sudden convulsion does not bring on the catastrophe.

Many of these symptoms are common to worms, teething, and other causes irritating by sympathy the brain, so that it is difficult to fix upon any which particularly characterize the disease. In general, in the early stages, the costiveness, with marks of irritation in the bowels, are the first appearances which lead to a suspicion; but the screaming, the slow pulse, and the squinting, are the only pathognomonic symptoms. The pulse sometimes sinks to forty in a minute.

There is a spurious kind of hydrocephalus, similar to the spina bifida. It appears on the lower part of the occiput like a bladder of water, and underneath the bone is deficient. Opening it would be as fatal as the opening the tumour of the spina bifida.

The disease both in its pathology and cure is still defective. The more obvious cause on dissection is an accumulation of water in the ventricles, generally attended with considerable fulness of the vessels; but the quantity of fluid is by no means in proportion to the violence of the symptoms; and in many instances where there is no considerable degree of compression from the accumulated water, the worst consequences often follow. These circumstances have led practitioners to suppose, with great reason, that the dropsy is only the effect of a previous disease of the brain; and those, who have brought this opinion into any distinct shape, have thought it to be inflammatory, or an apoplectic fulness of the vessels. The author who supposes it to be inflammatory is Dr. Rush of Philadelphia, and he thinks early and active bleeding a certain remedy. In this idea, he was preceded br Dr. Quin of Dublin, and has been followed by Dr. Garnett; though these authors have not been equally confident of the success of the remedy. It is necessary therefore to examine the subject more closely.