6 Penna. Hospital Reports, vol. i.
(2) Neuralgia.—Many observers have regarded myalgia as a neuralgia, having its seat in the muscles. Valleix7 wrote as follows: "Muscular rheumatism and neuralgia have, in the correspondence of their symptoms, their course, their exacerbations, in the absence of appreciable anatomical lesions, the greatest resemblance to each other. These affections often pass the one into the other.... The pain, which is the capital symptom of neuralgia, expresses itself, according to our observation, in three ways: If it remain concentrated in the nerves, characteristic isolated painful points are found; here is neuralgia properly so called. If the pain is diffused among the muscles, muscular action is principally painful; we have muscular rheumatism. Finally, if it be spread out upon the skin, an excessive sensibility of the cutaneous surface results, and there exists a dermalgia. These three forms of an affection which is the same may all be present at the same time, or two and two—neuralgia and dermalgia, neuralgia and rheumatism, rheumatism and dermalgia." No wonder he found nothing more difficult than to trace with exactitude the picture of this malady.
7 Loc. cit.
Flint8 also regards myalgia as closely allied to neuralgia, and states that, "being one of the neuroses, it has no anatomical characters." It is not difficult to trace the results of this teaching in the widespread confusion prevalent in regard to some very common painful affections, as, for example, that painful form of stitch known as pleurodynia, and the still more distressing gastrodynia. Even those observers who refuse to class these affections as rheumatic are too often at a loss as to whether they are neuralgic or purely muscular. Anstie9 has concisely contrasted the most important characters of neuralgia and myalgia in a way that strongly urges the clinical differences between them, as follows:
| NEURALGIA. | MYALGIA. |
| Follows the distribution of a recognizable nerve or nerves. | Attacks a limited patch or patches that can be identified with the tendon or aponeurosis of a muscle, which, on inquiry, will be found to have been hardly worked. |
| Goes along with an inherited or acquired nervous temperament, which is obvious. | As often as not occurs in persons with no special tendency. |
| Is much less aggravated, usually, by movement than myalgia is. | Is inevitably and very severely aggravated by every movement of the part. |
| Is at first accompanied by no local tenderness. | Distinguished from the first by localized tenderness on pressure as well as on movement. |
| Points douloureux, when established at a later stage, correspond to the emergence of nerves. | Tender points correspond to tendinous origins and insertions of muscles. |
| Pain not materially relieved by any change of posture. | Pain usually completely, and always considerably, relieved by full extension of the painful muscle or muscles. |
8 Practice of Medicine.
9 Neuralgia and Diseases that Resemble it.
(3) Inflammation.—That the muscular affection under consideration should have been referred to morbid processes of an inflammatory kind is very natural. The use of the term myositis embodies this view, which is held, among others, by Garrod. This author defines muscular rheumatism as "an affection of the voluntary muscles of an inflammatory nature (?), but unaccompanied with swelling, heat, redness, or febrile disturbance." He assigns the combined influence of cold and damp as a cause, especially when associated with over-use of the muscles.
Though some of the gross characters of inflammation are wanting, and the course of acute cases of myalgia is toward a speedy resolution, there are several features of the affection which strongly suggest its inflammatory origin. At all events, the view that the essential pathological conditions consist in a hyperæmia with slight serous exudation, or a partial paralysis of vaso-motor nerves with escape of serum into the intimate tissues of the muscles, has, from a clinical standpoint, much to support it. In the absence of knowledge derived from the actual investigation of the morbid tissue-changes in all the stages of the affection some value is to be accorded to the following facts as confirmatory of this opinion:
It is a local affection; the onset is usually sudden; there is often, from the beginning, a slight but obvious fulness of the muscle; tenderness is present as well as pain; in chronic cases inflammatory increase of connective tissue occurs, with changes in the nerve-sheaths and fatty degeneration of muscle-substance. Moreover, the permanent contraction (contracture) which sometimes finally sets in is the same as that which follows true inflammation of muscles after injuries (traumatic myositis10).