Of other remedies which directly influence the neuralgic condition, the following are the most important: opium, aconite, gelsemium, phosphorus, belladonna, chloride of ammonium, cannabis Indica, croton-chloral, electricity, hydropathy, massage, counter-irritation, subcutaneous injections of water, chloroform, osmic acid, etc.; surgical operations.
Opium is usually employed only for the momentary relief of pain, but it has also been claimed that in small and repeated doses it may exert a really curative action. This should not, however, be too much counted on. Opium should never be used continuously for the simple relief of pain unless under exceptional circumstances, the danger of inducing the opium habit is so much to be dreaded. Moreover, both patient and physician are less likely to seek more permanent means of cure if this temporary remedy can always be appealed to. It is best given by subcutaneous injections of the various salts of morphine. The dose should always be small at first (gr. 1/12 and upward), unless the idiosyncrasy of the patient is already known; and there is probably no advantage in making the injections at the seat of pain or in the immediate neighborhood of the nerve supplying the affected part, except such as might attend the injection of any fluid (see below).
Belladonna (atropia), which is so often given with morphine to diminish its unpleasant effects, seems at times, even when given alone, to have an effect on neuralgia out of proportion to its anæsthetizing action, which is very slight. It is considered to be especially useful in the visceralgias.
Aconite, given, if necessary, in doses large enough and repeated often enough to cause numbness and tingling of the lips and the extremities for some days, will sometimes break up an attack, especially of trigeminal neuralgia,24 better than any other means; but its use is liable to depress the heart, and it is a dangerous remedy if not carefully watched. Some patients complain that it causes a marked sense of depression or faintness, and a feeling of coldness; and indeed its full therapeutic effect is sometimes not obtained until such symptoms as these are induced to some degree. The use of the crystallized alkaloid, aconitia, has the advantage of ensuring certainty of dose.
24 See Seguin, Arch. of Med., vol. i., 1879; vol. vi., 1881.
The susceptibility of different persons to this drug is so different that the dose should first be as small as 1/400 gr., but this may be repeated every three hours, and gradually increased to 1/100 gr., or until its physiological effects are felt. Patients must sometimes be kept under its influence for weeks together.25 It is, however, a remarkable fact that occasionally a few full doses will secure an immunity from pain for a long period. Although most useful in facial neuralgias, the writer has known it to be effective in brachial and mammillary neuralgia. Aconitia can now be had in granules of 1/400 gr., or can be given in alcoholic solution.
25 See Seguin, Arch. of Med., vol. vi., 1881.
Gelsemium is also occasionally very useful in facial and even in intercostal neuralgia, and is said to be of special service in the neuralgia due to carious teeth. The commencing dose of the fluid extract is five minims, which may be gradually increased to twenty, or until a slight degree of muscular prostration, ptosis, or dilatation of the pupil is induced.
The use of phosphorus has been revived of late years, chiefly through the efforts of J. Ashburton Thompson, and it is at least occasionally of service. Success is said to be best obtained by full doses (about 1/20 gr. every three or four hours, up to 1/5 or 1/4 gr. daily for some days), watch being kept for signs of gastric irritation. The best preparation is an alcoholic solution (Thompson's), such as the following: