In 1939 Davis and Rommel1 reported a series of twenty-four cases of deafness and tinnitus aurium treated with prostigmine methylsulfate hypodermically, along with oral administration of prostigmine bromide. They concluded that patients with acute symptoms usually had restoration of hearing following five or fewer injections, that chronic cases showed encouraging results but responded less rapidly, and that tinnitus aurium was relieved or reduced.
A critical study of this work revealed that accurate hearing tests have not been used in the estimation of hearing loss both before and after treatment. On this account a letter was sent to the company manufacturing the drug stating this fact and asking if the company would cooperate in a comprehensive and well controlled clinical study of the effect of the product on hearing and tinnitus in several Philadelphia clinics. Full cooperation was obtained, and an adequate supply of materials was furnished for the test.