390 NELSON W. JANNEY 



Experimental studies have emphasized the delay in regenerative processes 

 taking place in the peripheral neurons after thyroidectomy (Walter (a-), 

 Marinesco and Minea). Myxedematous infiltration in and around the 

 nerves may aid in causing functional deficiencies. 



Few observations have been made on the pathological changes in the 

 organs of special sense. With regard to the auditory apparatus, Sieben- 

 mann found in thyroaplasia a normal condition so far as anatomy goes. 

 There is no question, however, as to the dullness of hearing in myxedema 

 and cretinism and its relief by thyroid therapy; von Wagner believed 

 that myxedematous swellings of tympanum, etc., were present, but Denker 

 was unable to confirm this in careful animal experiments. We must there- 

 fore accept cortical deafness or an extremely high grade of sound forget- 

 fnlness as the chief auditory disturbance present. 



Cardiovascular System. In certain cases of hypothyroidism there is 

 encountered a general hypoplasia of heart and vessels. The heart muscle 

 is severely affected. Cardiac enlargement with the clinical signs of myo- 

 cardial degeneration are not uncommon at an early age in cretinism and 

 myxedema. On account of the lowered resistance, valvular disease is rather 

 often met with. For further allusion to the forms of goiter heart see under 

 Cretinic Degeneration. An interesting illustration of degenerative proc- 

 esses which are hastened by a deficient supply of thyroxin to the tissues 

 is the early appearance of arteriosclerosis in hypothyroid subjects. It is 

 surprising how frequently this condition is discovered if sought for. The 

 pathologic changes are those usual in arteriosclerosis from other causes, 

 i. e., atheroma and calcareous deposits. The consequently increased per- 

 meability of the vessels walls may possibly account in part for the true 

 edema which, in distinction to myxedema, is sometimes present in the 

 lower limbs of cretins. The pathological changes in the blood are described 

 in the clinical section. The blood pressure is usually low. 



Gastro-Intestinal System. The lingual lesions include hypertrophy 

 of the papillae and mucous membrane, as well as an increase in the inter- 

 stitial tissue which may not be myxedematous. 



The gastro-intestinal tract suffers in a trifold manner. Weakness of 

 the muscularis coat produces gastric and intestinal atony to which the sub- 

 functioning nerve supply, itself in a deficient state of nutrition, con- 

 tributes. Thirdly, the digestive glands fail to supply properly elaborated 

 secretions for the same reason, and on account of the swelling of the lym- 

 phoid tissue. The liver is at times enlarged, infiltrated and congested. 

 Due to the swelling of the bile ducts and the slow flow of bile, gall stones 

 are commonly found according to Hertoghe, who also considers the sallow 

 complexion of the myxedematous subject due in part to biliary absorption. 

 The antitoxic properties of the liver are also interfered with. 



The Osseous System. The osseous system in hypothyroidism, espe- 

 cially cretinism, is the seat of early, important and extensive changes. The 



