SCIENTIFIC PROCEEDINGS. 



Abstracts of Communications. 



Sixty-ninth meeting. 



Cornell University Medical College, October 20, 1915. President 



Lusk in the chair. 



I (1065) 



As to the cause of the dilatation of the subclavian artery in certain 

 cases of cervical rib. — Experimental Study. 



By W. S. Halsted, M.D. and Mont Reid, M.D. 



[From the Department of Surgery, Johns Hopkins University.] 



In twenty-four or more instances a circumscribed dilatation of 

 the subclavian artery has been observed in cases of cervical rib. 

 The dilatation in these cases is distal to the site of pressure made 

 by the rib. 



As to the cause of these aneurisms there has been considerable 

 conjecture, usually prefaced by the comment that their occurrence 

 would be comprehensible if they presented on the proximal instead 

 of on the distal side of the compression. 



Weakening of the wall of the artery from erosion or trauma, 

 variable or intermittent pulse pressure, and vasomotor dis- 

 turbances in nutrition are the suggestions which have been offered 

 to explain the phenomenon. 



For several years my experiments in arterial compression have 

 had more or less in view the determination of the cause of this 

 dilatation. For the past year they have been continued by Dr. 

 Mont Reid and myself almost exclusively with the object of 

 shedding light on this problem. In 1906 we (Dr. Richardson, 



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