This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol1", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
In nervous deafness, faradisation of the chorda tym-pani has been followed by happy results. Great care must be exercised in conducting this operation. While the patient lies on his side, the meatus auditorius should be half filled with water; a wire connected with one of the poles should then be introduced so as to touch neither the tympanum nor the walls of the passage; and the wet sponge excitor, connected with the other pole, should then be applied to the nape of the neck. The slightest power of the instrument should be first exerted; not greater than may be sufficient to cause the least possible sensation when the excitors are applied to the end of the tongue; and then increased as may be found necessary. A slight buzzing sound is first produced by this operation in the ear when healthful, followed by tingling, and then, with the increase of the force of the current, by severe pain; the tingling, with a sense of numbness, extending to the side and anterior part of the tongue. There is also a peculiar taste produced. M. Duchenne has seen this process cure, in a short time, cases of deafness which had long resisted energetic measures, under the most competent practitioners. It is not impossible that the same measure might be useful in deafness of organic origin, provided all acuteness of symptoms had passed. The functional disorders of hearing which are so common, and so frequently alluded to by writers under the name of tinnitus aurium, often yield with the utmost facility to the remedy. It is asserted that galvanism has proved useful by promoting the absorption of pus and coagulable lymph in the cavity of the tympanum, and in exciting the secretion of wax when deficient.
In paralytic conditions of these functions, as well as in palsy of the muscles of the tongue, the application of electricity may be made in the manner stated in page 520.
Stammering, which may possibly sometimes be connected with debility of the muscles of the tongue, and other parts concerned in articulation, is said to have been benefited by a galvanic current directed from the tongue to the surface of the throat.