ACEOMEGALY 829 



origins and insertions of muscles become increasingly sensitive to the trac- 

 tion of the muscle fibers ; the muscular impressions and processes of the 

 skeleton become unduly raised, extended and emphasized by the formation 

 of new bony matter. The parts and articular surfaces of bones exposed to 

 repeated pressure or tension become the seats of growth." 



Keith wishes to call particular attention to the following two points: 



1. That the changes in acromegaly are of the nature of true growth 

 and are apparently due to the circulation through the body of a substance 

 formed in the pituitary. This substance seems only to sensitize the tis- 

 sues, the actual cause of this growth being mechanical stimuli arising from 

 muscular action and mechanical movement. 



2. The growth changes seen in the acromegalic are of the same nature 

 as those which occur normally in anthropoids and the Neanderthal race 

 and both are probably due to a condition of hyperpituitarism. 



Sternberg, in his monograph, makes the following general statements 

 regarding the bone changes : a The disease is generally symmetrical, but 

 of a pair of bones, onemay be more markedly affected than the other. The 

 deepening of the canals for the vessels, dilatation of the vessel foramina, 

 and strengthening of the points of attachment for the muscles and liga- 

 ments are typical. As a result of this, the bones acquire a coarse appear- 

 ance, and the normal roughness of the surface is thereby increased. This 

 change of shape exhibits a partial exaggeration of the normal proportions. 

 Moreover, small exostoses appear on the outside of the muscular and liga- 

 mentous attachments. Minute consideration of the normal topographical 

 relations is often necessary regarding these osseous deposits to distinguish 

 them from the former. They are small, rarely prickly, and are placed 

 most abundantly on the bones of the base of the skull, vertebrae, pelvis, and 

 chest, very few on the bones of the extremities. They are far more scanty 

 than the normal strong points and prominences. Prickly, warty, stalacti- 

 form exostoses are never found to any great extent in true massive acro- 

 megaly on normally smooth parts of the bones. Typical, further, is a pecu- 

 liar growth of some bones (lower jaw, bones of the air sinuses, sternum). 

 The tumor of the pituitary body produces in most cases special changes in 

 the sphenoid bone. The extent of the changes depends naturally on 

 whether, on dissection, the case is found to have reached an early or later 

 stage." 



More recently, Biedl, in his book on Internal Secretion thus character- 

 izes the skeletal condition : "The changes in the bones arc not as pro- 

 nounced as the clinical symptoms would seem to show. The ends of the 

 bones and the terminal phalanges are undoubtedly broadened and enlarged, 

 but this is chiefly due to exostoses and irregular absorption of the cortical 

 layers, and to bony outgrowths at the joints changes which must be re- 

 garded as secondary results of the hyperplasia of the soft parts. ^ 

 clavicle is usually very much enlarged. In addition to the changes in the 



