Asthenia hypophysopriva: neuromuscular symptoms due to alterations in the pituitary

Abstract

In the advanced stages of confirmed pituitary insufficiency there is a neuromuscular asthenic syndrome which occurs constantly, intensely and characteristically in the toad, during certain stages in the rat, and in a less marked form and not so constantly in the dog. It is very well developed in human cases of pituitary cachexia. The syndrome seems to result mainly from functional changes in the central nervous system, the peripheral motor changes playing only a secondary role. Evidence for this is given by: (1) the experimental analysis carried out in the asthenic toad; (2) the early and marked alteration in the postural and phasic reflexes in these toads, while the motor nerve and muscular excitability is still normal; (3) the coexistence of convulsions of central nervous origin with the asthenia; (4) the association with mental alterations in human cachexia and the changes in behavior of other animals; (5) the lowered blood pressure and hypodynamic vascular reactions. (See our lecture on, Hypophysis and Blood Pressure.!) The functional changes seem to have a metabolic origin since they coincide with general nutritive changes (decrease of blood sugar and glycogen, increase of sensitivity to insulin, decrease of the endogenous nitrogenous catabolism, etc.). Adrenal insufficiency which occurs frequently in cases of pituitary insufficiency, probably increases the asthenia but it is not certain, nor even likely, that the asthenia has an exclusively adrenal origin. Cortin does not correct asthenia hypophysopriva as does the anterior pituitary extract. It is more probable that there is a direct metabolic action of the pituitary hormone. On the other hand the actions of the adrenals and pituitary on the carb&hydrate metabolism have a certain similarity (the gly- cogenetie action, etc.) and anterior pituitary extract has a diabetogenic activity in adrenalectomized toads. Pituitary asthenia, therefore, appears to be due to general nutritive changes which principally affect the function of the central nervous system.