(From the head, and pain). The headach. It is also named cephalae, cephaloponia, and homonopagia. It is sometimes used to signify a dull pain of the head, of a short duration; but most frequently it is the appellation of pain in the head in general, without regard to circumstances, and is sometimes acute, and sometimes chronical. When mild it is called cephalalgia; when inveterate, cephalaea. When one side of the head only is affected, it takes the name of he-micrania, migrana, hemipagia, and megrim: in one of the temples only it is entitled crotaphos; and that which is fixed to a point, generally in the crown of the head, is distinguished by the name of clavas hystericus: q. v.

The nervous membranes of the head are the general seats of its pains, as the pericranium, the skin, dura mater, the membrane which covers the sinus in the os frontis, etc. This complaint is considered as symptomatic by Dr. Cullen; but as an idiopathic affection by other nosological writers. See Vogel, Sagar, Linnaeus, Macbride. Sauvages places it under his seventh class dolores, and second order dolores capitis; of which the cephalalgia and cephalaea form two distinct genera. See Nosologia Methodica, vol. ii. p. 49.

Undoubtedly pain of the head is often symptomatic; yet, as in many cases it is impossible to ascertain the disease of which it is a symptom, and in some is unconnected with any other complaint, it must be often considered as idiopathic. When we explain the arrangement of diseases, we shall find it difficult to avoid an order, at least, of dolores; and under this head cephalalgia must be arranged. If we were already to anticipate definitions, which we have cautiously avoided, we would say that it is a pain confined to the forehead and occiput, unconnected in every instance with the bones of the face, except when periodical. In this way it is at once distinguished from the tic doloureux (the dolor crucians faciei of Fothergill), diseases of the teeth, of the different antra, and of the eyes.

In this view, headach is a disease of the brain when idiopathic; and, though a symptom of apoplexy, of mania, and other diseases, yet, when alone and uncom-bined, when the series of symptoms which distinguishes these diseases is absent, and headach alone present, it must certainly be considered as of itself a disorder. As such, we find it produced by extraneous bodies pressing on the brain. These have been bony fragments, separated from the internal table of the scull, irritating the brain, while the accident that occasioned their separation was, at a distant period, unknown or unobserved. In some cases no such accident seems to have occurred; and the cause, only discovered by dissection, is unknown. The irritating bone has, in some instances, not been separated; but, has sprouted from the internal table of the skull in the form of an exostosis. This seems to be the cause of the obstinate head-achs arising from an old neglected venereal complaint; headachs which we have sometimes seen terminating in epilepsy. The falx has been found to be bony, without producing headach; and, on the contrary, the meninges of the brain have been discovered in a thickened state after headachs the most violent. In the last case it is probable that the thickening of the membranes was owing to chronic inflammation; and that the latter occasioned the pain. The pineal gland has been sometimes found hard, and filled with stony concretions, which seem to have been the cause of obstinate headachs; and Dr. Blane has found a tumour in the situation of this gland occasion the disease, as well as aneurisms of those branches of the carotids that surround the sella turcica. The distinction of these cases is very difficult: the pain is not always constant. In some instances it is violent only when the circulation is greatly accelerated; in others it occurs irregularly, without any obvious cause for its exacerbations. We have not mentioned the worms generated in the brain, recorded by Schenkius, as this author's narratives are more often wonderful than probable; and abscess in the brain more often produces lethargy and coma, than cephalalgia.

It may be doubted whether other causes do not sometimes produce pain in the head, which are still less easily traced. Accumulation of water often occasions uneasiness and symptoms of irritation, before those of compression come on. The peculiar kind of circulation through the brain; viz. the collection of the venous blood in sinuses, greatly favours accumulation, and may be a cause of pain. We hear also of a spasmodic contraction of the meninges; and the idea has been supported by a peculiar feel, as if the brain was grasped by a strong hand. Yet we cannot admit of the contraction of a membrane in which no muscular fibres are discoverable, and the sudden distention of their vessels-may produce the peculiar sensation just mentioned. We find also cases of mania and idiotism, where violent pain preceded the irregular exertion or extinction of the mental powers, in which the brain has been found unusually dry, or peculiarly soft. We know not the cause of these changes; nor can we trace the connection of their effects; yet, as they have been causes of pain, we may suppose that, in some obstinate cases, they may produce this symptom without proceeding to similar distressing terminations. There is at times a morbid sensibility, the concomitant often of genius, winch predisposes to, or causes, this disease. It seems as if the man of genius suffers from the same source that gives him the superiority to the rest of mankind. In such a constitution, as in inflammations of the skin, of the eye, or ear, a fly may excite pain; a ray of light, or the slightest sound, be more pungent than the midday sun, or the explosion of a mine.