Solar Stroke

SOLAR STROKE (insolatio, siriasis, solar apoplexy), a severe lesion of the central nervous system with its most important nerve centers in the medulla oblongata, caused by intensive or prolonged action of direct sunlight, mainly on the crown and occiput, with there also being a general overheating of the organism due to the penetration of light heat rays into the depth of tissues. In recent years some authors (Steinhausen, Mohr, de la Camp) identify solar stroke with heatstroke, but such an understanding is hardly fully justified, since heatstroke occurs mainly under conditions of overheating of the whole body, mostly in closed premises, whereas in solar stroke the greatest overheating affects the head uncovered or in a heavy headgear in hot times of year and day, especially in a hot climate. Overheating is facilitated by dense, dark-colored, non-porous clothing, heavy equipment or load during movement (in marches) and generally increased muscular activity (field work) at high humidity and lack of air movement. But solar stroke can also occur in a calm state, during prolonged lying, and especially while falling asleep under the scorching rays of the sun. Predisposing factors are unfamiliarity with overheating and staying in the sun, obesity, overfilling of the stomach and intoxication. Initial symptoms of solar stroke: a feeling of being beaten, pressure and more or less sharp pain in the head, dizziness, flashing before the eyes, disturbance of vision, noise in the ears, sometimes disturbance of swallowing, nausea and vomiting, pain in the epigastrium, paresthesias. Objectively visible general weakness, redness of the face and head, local and general increase in body temperature, first to 38-38.5°, then to 40° and higher, rapid increase in pulse and respiration, profuse sweating. Upon cessation of the action of sunlight rays and overheating in this period, especially if appropriate measures are taken, these phenomena gradually smooth out. The characteristic symptom complex of solar stroke, developing with continued action of sunlight rays and overheating: general prostration, loss of consciousness, body temperature remains high, but may rise even higher to 42-44° or even to 46-47° or may slightly fall; respiration remains frequent but regular, then slows down, and may pass into Cheyne-Stokes respiration, and in severe fatal cases stops due to paralysis or paresis of the respiratory center; pulse, initially frequent and full, slows down, becomes tense, its rhythm may be disturbed and finally weakness sets in due to a drop in cardiac activity; in the lungs there may be signs of stasis and even edema; sweating in this period ceases, but later a more scanty sweat reappears due to paralysis of the vasoconstrictors. Blood changes relatively slightly, although loss of water causes an increase in viscosity, which hinders circulation and leads to disruption of the integrity of capillaries with subsequent small hemorrhages in the brain and internal organs. Lesion of the central nervous system manifests in the form of drowsiness, twilight state, clouding of consciousness with decreased or increased reflex excitability; twitching, cramps in individual muscles and general epileptoid attacks are very often observed, a comatose state and finally signs of partial or general paresis or paralysis, with loss of reflexes and absence of pupillary reaction. In other cases, general excitement, hallucinations, state of fear, and "heat" delirium come to the fore. The pathoanatomical essence of solar stroke is overfilling of the blood vessels of the brain and its membranes with small hemorrhages and edema phenomena, in particular of the cerebral cortex, gray matter of the central canal, pons Varolii, and medulla oblongata, with the important brain centers suffering. Under microscopic examination, widespread changes in chromophilic granules of ganglion cells, degeneration and disintegration of their nuclei are found. Severe brain phenomena, however, often last only for several hours or a day. Prognosis in hyperthermia above 40.5°, delirious state is unfavorable; in the presence of sweating it is favorable. Outcome. With timely medical aid, consciousness returns after deep, sometimes prolonged sleep, although various general disorders almost always remain: drowsiness, feeling beaten, dizziness, headache, especially in the forehead; thirst, lack of appetite; pain and cramps in various muscles; vasomotor disorders with increased excitability or slowing of pulse, increased respiration and shortness of breath, body temperature is often lowered, urine is excreted in small amounts. More severe neuro-psychic disorders are also often observed: twitching, pareses, paralyzes, apathy, fear and tearfulness, depression. Increased sensitivity to the action of high body temperature and alcohol is also worthy of attention. In this case, possible returns of the former diseased state with loss of consciousness and cramps and even death are observed more often during the recovery period. The general duration of the disease after solar stroke is from several days to several weeks. Persistent changes often manifest in the form of traumatic neurosis phenomena, sometimes changes in character, less often in the form of paralysis or dementia as a consequence of hemorrhage or degeneration in the brain substance. Death occurs with signs of paralysis of higher nervous centers. The general mortality from solar stroke in European armies is determined at 7-13%, apparently depending on whether more mild cases are taken into account. Among Europeans, especially those who arrived in countries with a hot climate not so long ago, solar stroke occurs much more often than among natives. Preventive measures: light, light-colored clothing that does not impede evaporation and the same headgear; reduction of physical exertion and load and more frequent breaks during work and movement under the sun's rays, it is important to avoid overfilling the stomach and alcohol; abundant introduction of fluid - 9-15 liters per day. Treatment must begin at the first manifestations of the disease: transfer the patient to a shaded, preferably cool place, free from clothing, cool the body by fanning, cold compresses and ice on the head, wet wrapping and pouring the body with cool water; cold baths and showers are not recommended, but warm baths (about 30°), with subsequent significant lowering of body temperature, can be considered expedient; intravenous or subcutaneous injection of physiologic solution is especially indicated in a more severe state; bloodletting is appropriate mainly with a tense pulse; artificial respiration, since with hyperthermia movements in general are contraindicated, is appropriate only if it is not possible to restore breathing by other means; stimulating agents have to be applied when cardiac activity falls, respiratory disorders and the beginning of pulmonary edema set in.