CUTANEOUS SYMPTOMS. — The skin usually appears congested and red, but it may be bluish red, very pale, or cedein atous. It is usually dry, hut a contrary condition sometimes prevails, drops of perspiration, giving off an unpleasant odor, covering the entire field involved. The nails may assume a curved, turtle shell-like shape, become furrowed, and undergo ulceration. This destructive ; process may involve the phalanges and end in gangrene of the fing-er-tips. Periostitis sometimes occurs. -Various cutaneous affections, eczema, herpes zos ter, pemphigus, etc., are also observed.
JCINTS.—The joints are occasionally involved secondarily, arthritis develop ing as the result of injury, not only of the nervous- supply of the limb, but also, at times, of lesions of the cerebro-spinal system. These arthropathics so simulate acute rheumatism sometimes as to sug gest the actual presence of the latter dis ease. Effusions into the joint, adhesive inflammation ending in aukylosis, dis locations of the articular surfaces, and even destruction of the entire joint have been noted.
WAsTiNc.—As soon as the nutrition of the muscles is impaired through solu tion of continuity of their nervous sup ply, marked evidences of wasting soon appear. Atrophy following division of a nerve is of the most pronounced kind; thc muscular structure, after a period of connective-tissue proliferation, com pletely disappears, leaving a mass of hard, fibrous tissue in its stead. The process of degeneration is accompanied by gradual contracture, the effects of which are deforming in proportion as the insertions of the affected muscles are far from tbe trunk. The hands often suffer in this connection, their usefulness being totally destroyed in some cases. The differential reactions shown by affected muscles when the electrical current is ap plied to them are very important; they are considered under PATHOLOGY.
Pathology.—When a nerve is severed, it begins to degenerate, the process fol lowing the direction of the nerve-cur rent. If a motor nerve be cut, the de generation will proceed in the same direction as motor impulses; these radi ating front the spinal cord outwardly, it will extend from the point of section toward the periphery. while, if a sensory nerve be severed, the degeneration will advance toward the spinal cord. Pro ceeding with rapidity, the destruction is sometimes completed within a few weeks. The entire peripheral segment, in the case of a motor nerve, becoines fatty and granular and its myelin and eventually its axis-cylinder undergo disintegration. In the case of sensory nerves, the process may extend into the spinal cord and even into the brain.
Changes occurring in nerve-cells after resection of their axis-cylinders are di vided into three phases: Reaction, re pair, and degeneration. Reaction is
characterized by solution of the chromo Philic bodies and dislocation of the nu cleus. During repair the body of the cell swells and the nucleus returns to its normal position. The hypertrophy reaches its maximum in about ninety days, and the cells appear perfectly nor mal, excepting that they are somewhat darker than usual. In the course of twenty days more the distinction be tween the normal cells and those in a state of repair has almost disappeared. When the nerve is torn out and its repair thereby prevented, the reaction-period is complete in the course of about twenty days. Then, instead of swelling and be coming pycnomorphous, the cells lose their chromophilic substance, and become smaller, and in the course of a month may have disappeared, and the others are atrophic. The protoplasm has be come translucent, the nucleus smaller and deformed, and, occasionally, the achromatic substance shows alterations. A few cells are very dark in color, partly from the retention of the ehromophilic substance and partly from the staining of the cell in mass. G. Marinesco (Neu ral. Centralb., Oct. 1, '98).
A muscle supplied by a severed motor nerve responds in a different way to the action of the galvanic current than one normally supplied. While in the latter case the cathodic (negative) closure con traction (K.C1.C.) is more marked than the anodic (positive) closure contraction (A.C1.C.), the opposite is the case when the nerve has been cut. In other words, the application of the negative current causes a more mark-ed contraction than the positive current, whereas in the nor mal state it is the negative current that gives rise to the stronger contraction.
The former is termed the "reaction of de generation." — The subsequent course of the injury depends upon the proximity of the two ends. If they are sufficiently close, union by first intention occurs, nerve-fibres being capable of un dergoing primary union in the same man ner as other tissues. The process starts from the nuclei and from the protoplasm of the sheath of Schwann (Biingner). There occurs rapid proliferation of the axis-cylinder and neurilemma of the proximal nerve-fibres, and these, once brought into contact with the peripheral portion of the divided nerve, retard and finally arrest the degenerative process. As soon as the union is sufficient to afford a suitable conductor for nerve-impulses (Vanlair) the process of repair begins, and continues until the functions are re stored. In a case reported by Notta all the nerves cut some distance above the elbow were thus regenerated within six months.