Sunstroke (Lat. soils ictus; Fr. coup de Soleil; Ger. Sonnenstich; also called insolation, heat apoplexy, heat asphyxia, and solar asphyxia), an affection which suddenly attacks persons exposed to the continuous hot rays of the sun or other sources of heat. The symptoms vary considerably, according to the extent and nature of the injury. The patient is usually attacked in the midst of his employment, although sometimes he is not seized till in the night, especially if occupying heated and badly ventilated quarters. There is loss of consciousness, and generally stertorous breathing and convulsions, and in the worst cases there is extreme prostration of the vital powers, and the voluntary muscles are motionless from the paralyzed condition of the nervous system, the greatly impeded functions of respiration and circulation being the only signs of life. The attack usually comes on in the afternoon, partly because this is the hottest part of the day, and also because the subject has generally been laboring for many hours, and his vital powers are more or less exhausted.

The attack may be immediately preceded by premonitory symptoms, such as pain and a feeling of fulness in the head and oppression at the pit of the stomach, sometimes attended with nausea and vomiting, and a feeling of weakness in the lower extremities, vertigo, and dimness of vision. In GO cases reported to the New York hospital by Dr. H. S. Swift ("New York Journal of Medicine," 1854), surrounding objects appeared of a uniform color, generally blue or purple, but sometimes red, and at others green. In light cases the insensibility may be momentary, but in severe cases the patient rapidly becomes asphyxiated or comatose. The pupils are sometimes dilated and sometimes contracted, and there may be dilatation and contraction at different stages in the same case. There is considerable and often very great increase in the temperature of the body. In cases observed at Bellevue hospital, New York, in July, 1868, it frequently rose to 109.5° F., and in one instance to 110.5°; and still higher temperatures are recorded. When it reaches 107° recovery is scarcely to be expected, although it took place in the one instance at Bellevue where it reached 110.5°. Vomiting during the unconscious period, and involuntary evacuation of the bowels, are very grave symptoms.

Although in many cases, as has been observed, the symptoms vary with the extent of the lesions, in the more pronounced cases they are rather uniform, the patient being completely without sensation or motion, except that of respiration, which is stertorous, though less than in true apoplexy. The eyes are fixed and turned upward with a glassy appearance; the pupils are greatly contracted, and the conjunctiva) are congested. Sometimes the whole system of voluntary muscles .will be convulsed, and more rarely the patients appear to be in a state analogous to somnambulism; but the more fatal cases are often entirely free from motion of the voluntary muscles. In reports of cases occurring in the British army in India, by Mr. Longmore, in which he designated foul air of badly ventilated quarters as an active cause, the pathological conditions found after death were markedly more those of asphyxia than of congestive apoplexy, there being excessive engorgement of the lungs, while the cerebral congestion was decidedly less. The blood remains uncoagulated after death, showing a loss of life in its organic constituents.

Thus, the post-mortem appearances accord with the symptoms, illustrating, as Mr. Barclay has pointed out, the four different ways in which death may take place, and furnish a key to the rational treatment of the different cases. 1. The intense heat of the sun's rays, pouring down upon the head, combined with great bodily exertion, may produce a state similar to that of nervous concussion from accident, and death may take place more or less suddenly by syncope. 2. When death does not quickly ensue, paralysis of the respiratory nerves may induce pulmonary congestion, terminating in asphyxia. 3. The cerebral may be much greater than the pulmonary congestion, and death may take place by coma. 4. Partial recovery may supervene, and the patient die in two or three days afterward, with serous effusion within the cranial cavity. Rather more than half the cases of sunstroke are fatal, death sometimes occurring in a few minutes, but oftener in a few hours, the average perhaps being from three to four, the patient remaining in a comatose state till the end of life. - The treatment has been a matter of much discussion, and for cases having marked apoplectic or comatose symptoms it is so still.

Some contend that bloodletting may be advantageously employed, while others strongly oppose it in all cases, maintaining that there is always a degree of vital depression which forbids it. This is the position generally held by the surgeons of the English army in India. The principal remedies relied upon in nearly all countries are stimulation to the surface, especially along the spine, by sinapisms or blisters and electricity, and the administration of stimulant and purgative enemata containing alcoholic spirits; the bathing of the surface of the body with tepid or warm water containing ammonia or carbonate of soda; and the application of the cold douche to the spine and of cold to the head. The hair should be cut short, and in the worst cases blisters may be applied to the nape of the neck and along the spine. When the breathing is very difficult and the bronchial tubes are clogged with mucus, the patient should be often turned upon the side and face. Beneficial effects have sometimes been found from the inhalation of chloroform, but the use of this requires great caution.

Promptness and decision are necessary, and the services of a physician should be procured as quickly as possible; but cold to the head, sinapisms, and stimulating enemata may be employed before his arrival.