Mydriasis in Scorpion Envenoming Syndrome: Insulin administration reverses cardiovascular changes, pulmonary edema and all other clinical manifestations

Death due to poisonous scorpion stings of Buthidae family is a common event in many of the developing countries located in the tropical and sub-tropical regions of the world. Severe scorpion envenoming causes an autonomic storm with massive release of catecholamines, renin-angiotensin II, glucocorticoids, glucagon, growth hormone, simultaneous suppressed insulin secretion, hyperglycemia and a sudden increase in Free Fatty Acid levels (FFA). Sudden increase in FFA is toxic, causes acute myocarditis, cardiogenic shock, disseminated intravascular coagulation, systemic inflammatory response syndrome, multi system organ failure and death. The victims present with mydriasis, papilloedema, nystagmus, squint, miosis, vomiting, profuse sweating, increased salivation, generalized tingling, gangrene, priapism, tachypnoea, hypertension, hypotension, pulmonary oedema, and many other manifestations either singly or in combination. Wide dilated pupils not responding to light is one of the grave signs of scorpion poisoning. Insulin administration reversed all the metabolic and clinical manifestations in our experimental animals and scorpion sting victims. Continuous infusion of regular crystalline insulin at the rate of 0.3 U/g glucose and glucose at the rate of 0.1g/kg body weight/hour, for 48-72 hours, with supplementation of potassium as needed, maintenance of fluid, electrolytes, acid-base balance reverses the metabolic, haemodynamic cardiovascular changes, pulmonary oedema and all other clinical manifestations in scorpion envenoming syndrome. Normal pupil reacting to light is one of the indications of recovery. Insulin is an anabolic hormone, acts against the metabolic and poisonous effects of all the counter regulatory hormones; has a primary metabolic role in preventing; counter-acting, reversing all the deleterious toxic effects of FFA by inducing lipogenesis, increase intra-cellular K + and euglycemia. The neurological and patho-physiological basis of mydriasis, nystagmus, and few other manifestations involved in the genesis of scorpion envenoming syndrome and their reversal by administration of insulin is reviewed.