HERPES Z OSTER (SHINGLES; ZONA).
Definition.—Herpes zoster is an acute inflammatory disease of the skin, appear ing in the course of certain cutaneous nerves, accompanied by severe nerve pain, usually unilateral in the distribu tion of its lesions and characterized by the occurrence of groups of firm, tense. globoid vesicles rising from an oedem atous base.
Symptoms.—The outbreak of the eruption is nearly always preceded by a severe nerve-pain in the neighborhood of the area about to be attacked. Occasion ally it occurs at a considerable distance from the part. The onset of the pain is usually sudden. The patient retires at night in apparent good health and after resting well for a number of hours is suddenly awakened by a "stitch in the side." Or after a hearty meal he lies down for an after-dinner nap and rises at the end of the period with a feeling of general discomfort, quickly followed by fierce stabbing sensations in a given lo cality. The pain is generally sharp and lancinating, but it may be dull, heavy, and boring. It is nearly always of suffi cient severity to interfere with the pa tient's usual vocations and may become almost intolerable. The rest at night is often broken and the patient then grows pallid from loss of sleep. There is usually no fever or preceding rigor. Sometimes there is slight chilliness, and there may have been malaise and gradu ally growing indisposition for a number of days preceding the onset of the at tack.
In some rare instances the outbreak is not accompanied by any feelings of distress. This is more apt to be the case in children than in adults.
The appetite for the most part remains good; but, owing to the insufferable nature of the pain, nausea and even anorexia may at times be incited. The functions of the different organs are, in general, conducted with their ordinary regularity.
The attack of pain may make its ap pearance days and even weeks before the eruption shows itself, but usually the vesicles follow in the course of a few hours. A reddened or bluish-red patch of the size of a half-dollar silver piece or larger is first exhibited. This area rises
to the height of two or three lines, is sharply defined, and is exceedingly ten der to the touch. So painful is it that often the friction of the clothing can scarcely be borne. The discoloration deepens and there is a sensation of heat or burning in the patches. In a very short time the vesicles appear.
The vesicles in herpes zoster when fully formed are unlike those seen in any other disease of the skin. They rise from the surface of the oedematous patch freely and distinctly, often having the appearance of being stuck on instead of forming an integral part of the tissues.
They are tense, clear, and glistening, are oval or circular in outline, are al ways in groups, and the roof-wall in each is so firm that they do not ordinarily rupture unless subjected to mechanical violence.
At the outset the vesicles are filled with clear, translucent serum. This, in the course of a few days, grows cloudy in color and later becomes purulent. Hemorrhage sometimes discolors the contents of the lesions. The number of vesicles in each group varies from three or four to one or even two dozen. They are usually from a split pea to that of a coffee-bean in size, but occasionally when very numerous are not larger than a mustard-seed. When small the lesions are much more likely to break down. In most cases from three to a half dozen groups may be found, but this number may be less or it may be greatly in creased. The clusters are generally found following the course of a certain cutaneous nerve; but, because of the overlapping of the filaments from differ ent trunks, it is frequently difficult to determine the particular branch which is affected. The distribution is nearly always unilateral, but where the disease is severe the limits of demarkation are not sharply drawn at the median line, and the disorder may trespass upon it to a marked extent. This is due to the extension of nerve-filaments from one side of the body to the other.