A disease of the nerves, so called from a pain in the nerve. It is a form of nervous affection, that may either arise of itself, or be the result of some other constitutional disturbance. Neuralgia may either attack the root of the nerve, or where it arises from the brain or spinal marrow, attend its whole course, or only manifest itself in its branches, or even at the final termination of its smallest filament. According to the part affected, the disease has obtained different names. When the course of the nerve is affected, as in the hip or leg, it is called sciatica; when the extremity is affected, if in the teeth, it is called tooth-ache; and when the twigs and branches of the face are involved, tic-douloureux. The pain attending all neuralgic affections, is of the most acute and agonising description, being sharp, sudden, and plunging; coming on in a moment, and after a paroxysm of intense suffering, abating as abruptly as it commenced; and so erratic and uncertain are its attacks, that it will sometimes be induced by the most trivial motion, action, or lightest contact, while, not unfrequently, a blow or hard pressure has no effect on the part. The twitching, or tic, that attends neuralgia so frequently, is always more marked where there are many small muscles in the neighbourhood, an aching numbness being left in the part for some time after the subsidence of the more acute pain. Neuralgia, as well as attacking the root, course, and extremities of a nerve, occasionally shows itself in the organ to which the nerve ultimately distributes itself, as in the heart, in _angina pectoris_, the breasts of females, and other organs. Though the subject of neuralgia has been deeply investigated, no satisfactory hypothesis has been yet come to, to account for the origin of the disease; and whether it depends upon a morbid state of the nerve, inflammation of the neurilemma, or sheath of the nerve, from pressure, or some unhealthy condition of the nervous centres, is still an undecided question. The treatment of this most agonising disease must depend, as far it can be ascertained, upon the supposed cause. When it is symptomatic, the treatment is much easier and more simple, and must be regulated by that cause, the first endeavour being to remove the primary disease, and after brace the system by chalybeate, tonics, wine, bark, and exercise. When idiopathic, however, the most opposite treatments have occasionally been successful, and sometimes all modes of cure have failed; and when physician and patient have both been exhausted with fruitless efforts, the malady has subsided of itself. As a general rule, however, the constitutional tonic and anodyne system, with counter-irritation, has been found the most successful practice; the three modes enjoined very frequently effecting what neither the tonic, the sedative, nor the local irritation alone could achieve.