Observations on the serum potassium with special reference to myotonia

Abstract

In two different branches of neurology there have been in recent years considerable advances in treatment.In the first group an outline has been given of the extension of our knowledge of the relation of disorders of nutrition to diseases of the nervous system, suggesting that further investigation along these lines may solve some of the problems of incur= able diseases of the nervous system.In the second group, composed of familial period is paralysis, myasthenia gravis and the myotonias, advances in our knowledge of treatment point the way to further investigations of neurological problems along quite another line. Reasons have been advances for considering these three diseases to have many features in common. Each of them has been known for about sixty years, and has remained during this time practically unamenable to treatment: but within the last two or three years a specific treatment has been found for all of them. The elucidation of the mode of action of these specific remedies and their relation to neuro-muscular conduction and muscular action emphasises the importance of a physiological rather than a morphological approach to problems in neurology.Familial periodic paralysis, myasthenia, gravis and the myotonias have been considered in relation to the potassium ion.The affect of insulin and glucose on the serum potassium has been investigated, and the findings have been discussed.On the analogy of deaths from cardiac failure in attacks periodic paralysis, a hypothesis that a very low serum potassium may cause death in diabetic coma has been presented.Some observations on the effect of quinine, beer, potassium, insulin and adrenal cortical extract on myotonia and on the level of the serum potassium in myotcnia have been recorded and discussed, with particular reference to the mode of action of quinine and alcohol in reducing myotonia.The relationship of migraine to familial periodi paralysis has been traced and the suggestion node that an investigation of migraine in the light of our knowledge of familial periodic paralysis is desirable.A short commentary has been presented on the points of interest in the three myotonic subjects who were the subject of the investigations.The following conclusions have been reached: -1. Oral quinine is a specific for myotonia but seer to act better in some people than in others. Quinine does not affect the weakness in dystrophia myotonica.2. Intravenous quinine is an undesirable and unnecessary method of treatment of myotonia.3. Beer improves some myotonics, but is without action on others.4. The administration of potassium makes myotonia worse.5. There is no direct relation between the level o the serum potassium and the degree of myotonia.6. Quinine has no direct effect on the level of the serum potassium, and the action of quinine in myotoni . cannot be explained by any action on the serum potassium.7. Insulin and glucose both depress the level of the serum potassium, and the combined effect is greater than the separate effect of either.8. The first symptoms of dystrophia myotonica may begin at an earlier age, and the patient may live to a greater age than has been hitherto thought possible