Neuralgia and the diseases that resemble it

by Francis Edmund Anstie

(a) Among the skin-stimulants blisters hold the highest place as a remedy for neuralgia; indeed the assertion of Valleix, that they are the best of all remedies, is still not very wide of the truth. They are by no means universally applicable, and the degree to which their action should be carried varies materially in different forms of the disease, but they are of the greatest possible service in a large number of instances.

It is possible to view the action of blisters in neuralgia in more than one way. When applied in such a manner as to vesicate decidedly, and especially if kept open and suppurating for some time, they cause considerable pain of a different kind from that of neuralgia itself and the mental effect of this, operating as a diversion of the patient's thoughts from his original trouble, may be thought to assist in breaking the chain of nervous actions by which he is made to feel neuralgic pain. There may be something in this, but I confess that I do not believe this kind of effect goes for much in genuine neuralgia. It is rather in the pain of hypochondriasis, and the so-called spinal irritation (to be described in the second part of this work), that such an action of blisters proves useful.

Another action of blisters, which some authors hold to be perhaps the most effective portions of their agency, is that which is produced by the drain of fluid, specially when they are kept open, by which means a kind of depletion is set up, and the morbid irritation that causes the nerve pain removed. I cannot at all assent to this view. In the first place, I believe that any one who has large experience of blistering in neuralgia will ultimately come, as Valleix did, to believe that prolonged drain from a blister is rarely or never useful, and that a far better plan is that of so-called flying blisters, renewed at intervals if necessary. The most genuine successes that I have procured from blistering have certainly been got in this way. But I should go further, and say that the prolonged drain and the peculiar kind of chronic irritation produced by a suppurating blistered surface can very decidedly aggravate a neuralgia; this is more especially the case when the blister is applied immediately over the focus pain.

The view which I am strongly convinced alone explains the beneficial action of blisters is that which supposes them to act as true stimulants of nerve-function. In order that this effect shall be produced, it will be necessary that the skin-irritation be either produced at some distance from the seat of the greatest pain, or that, if applied in that spot, it shall be comparatively mild in degree. And accordingly, I have been led, in my observations to apply the blister at some distance from the focus of pain. An indifferent point, however, will not do—there must be an intelligible channel of nervous communication between the irritated portion of skin and the painful nerve. This object is accomplished by placing the blister as close as may be to the intervertebral foramen from which the painful nerve issues; the effect of this is probably a stimulation of the superficial posterior branches, which is carried inward to the central nucleus of the nerve. I must say that the results which I have derived from this plan of treatment have been far more satisfactory than those which I used to obtain when I habitually applied the vesication as near as might be to the focus of peripheral pain; and I think that this result tallies well with the idea that the essential mischief in neuralgia consists in an enfeebled vitality of the central end of the posterior root. An exceedingly interesting confirmation of this idea as to its modus operandi has been afforded me by the fact that not merely neuralgic pain, but also trophic and inflammatory complications attending it, have been sensibly relieved, in several cases that I have seen, by this mode of reflex stimulation. This has been particularly the case in herpes zoster, where the process of inflammation and vesiculation has been very promptly checked by the application of a tolerably powerful blister by the side of the spine at the proper level; and I am gratified to mention that Dr. J. K. Spender, of Bath, pointed out this fact[39] at a time when he had only seen my statement that the pain could be relieved in this way. In the case of the trigeminus, the same kind of reflex stimulation is most effectively obtained by applying the blister over the branches of the cervico-occipital, at the nape of the neck; and it is remarkable what powerful effects are sometimes thus produced, even in cases that wear the most unpromising aspect. For example, in the desperate epileptiform tic of old age, I have more than once seen a complete cessation of suffering, which lasted for a very long time—so long, in fact, as to make me hope against hope that it might never return. I do not now entertain any such expectations from this remedy; still, its value is very great.

There are curious differences between the effects of blistering in trigeminal or intercostal neuralgia and in sciatica. On the whole, it would appear that blistering in the neighborhood of the spine is less frequently effective in the latter, and we sometimes, after failing with this method, obtain immediate success by two or three repetitions of the flying blister, somewhere over the trunk of the nerve, especially just outside the sciatic notch. I have one lady patient in whom this series of phenomena has several times been observed; and I have seen it occur in a particular attack, in other patients, in whom, nevertheless, on another occasion the spinal blistering has been promptly effective.

I consider blistering of the posterior branches to be an important, and usually an essential, element in the treatment of all cases of sciatica in the middle period of life which have reached some severity and lasted long enough to become complicated with decided secondary affections.

In all cases where blistering is employed it is advisable to adopt the simultaneous use of hypodermic morphia or atropine; this combination of remedies is exceedingly powerful.

Lastly, it must be said of blistering, that, on the whole, it is a remedy not well fitted to be applied to aged subjects; and in its severer forms it should never be applied to patients who are greatly prostrated in strength. For it must be borne in mind that the remedy may miss its aim of relieving the neuralgia, in which case it is necessary to remember, more accurately than many practitioners appear to do, what a very serious element of misery and prostration will be introduced into the case by the vesication itself.

I am not convinced that any of the other forms of severe skin-irritation (e. g., tartar-emetic inunction, or the use of veratrine-ointment to such a degree as to produce not the anæsthetic but the irritant effects) are of any particular value; if blistering failed, I should not expect to see them succeed.

A milder degree of skin-stimulation is represented by rubefacient liniments of various kinds, which may be briskly rubbed into the skin along the track of the painful nerve, without any danger of producing vesication. Among this class I continue to prefer chloroform diluted, with six or seven parts of chloroform, to any other; in the milder forms of neuralgia, especially in young persons and first attacks, it is surprising how frequently the paroxysm may be greatly relieved, if not arrested. Still, this can only be regarded as the merest palliative; and in severer cases such applications are useless. Occasionally, when chloroform-liniment has failed, a mustard plaster will do good.