64 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 93 



Burton (1927) is skeptical as to the influence of otic discharges: 

 " If the exciting agent be some form of chronic irritation and the 

 potentiaHties of all four walls be equal, we are surely entitled to 

 postulate that the floor, l)eing the most dependent part, would be the 

 wall receiving the maximum stimulation, and hence should be the 

 area most frequently productive of these overgrowths. But the floor 

 is hardly ever involved in the process. It follows therefore that we 

 are justified in premising etiological factors other than chronic irri- 

 tation " O. Mayer (q. by Alexander, 1930) does not believe 



that ear exostoses arise from a primary local inflammation. Moller- 

 Holst's material (1932, p. 102) " fails to show connection with otitis 

 media "; and he has also failed to find, in the mummies with ear ex- 

 ostoses, inflammatory processes in the soft parts. 



Discussion. — As with most other alleged causes of ear exostoses, 

 the question remains undecided. 



There is no question but that in a large majority of the clinical 

 cases the growths were found accompanied by otorrhoea and in some 

 by marked otitis media. But there were also observed cases without 

 any discharge or otitis, and a great many patients with otorrhoea or 

 otitis media develop no ear exostoses. 



A number of the aural surgeons reporting on the condition mention 

 that for long periods the growths caused no troul)le to the patient. 

 In general the subject is unaware of the hyperostosis or exostosis 

 until it reaches such a size that it l)egins to be accompanied by a 

 discharge or interferes with the hearing. But when conditions reach 

 such a stage, a determination of which was first, the bony growth or 

 the discharge and inflammation, is impossible. 



The fact that the growths almost never develop from the floor of 

 the meatus, which is most exposed to ear discharges, need not have 

 much significance, for in all probability, owing to differences in in- 

 nervation and blood supply, not all parts of the tympanic bone are 

 equally prone to the development of exostoses, and at night the dis- 

 charges liathe also the lateral ])arts of the meatus. 



Theoretically, it cannot but be acknowledged that any cause in- 

 ducing nerve irritation and reactive prolonged hyperaemia of the 

 meatus would be capaljle, where a " predisposition " to ear exostoses 

 existed in the parts, of arousing or favoring their development. Where 

 the predisposition does not exist or is held in check in some way, there 

 would, in all prol)ability, be no exostoses. Irritations and inflamma- 

 tions may thus be admitted as among the possible exciting causes of 

 ear exostoses, but hardly as the basic causes of such growths. 



