DISTURBANCES OF TILE EQUILIBRIUM.
has been mentioned that acquired deafness is often accompanied by disturb ances of the equilibrium, both at its first appearance and immediately afterward, and that this complication is most fre quent in cases where the deafness has been caused by cerebrospinal meningitis. Mention is also made in literature of some few cases of congenital deafness accompanied by disturbances of the equi librium, consisting in uncertain and stag gering, gait, both during the first years of childhood and later on in life. James 1N-as the first to draw attention to "im munity from dizziness," .under circum stances which otherwise produce dizzi ness and consequent disturbance of the equilibrium, as characteristic of deaf mutes. IIe examined altogether 519 deaf-mutes and found that 186—i.e., 36 per cent.—did not feel the least dizziness when spun round rapidly, no matter in what position their heads were placed. James was also informed by inany of these deaf-mutes that they experienced a remarkable feeling of helplessness and want of sense of locality when under water, several of them also stating that these sensations were unknown to them before the loss of hearing. Kreidl en
deavored to discover in a more rational manner, and by the aid of a specially constructed apparatus, an objective proof of the above-mentioned phenomena in deaf-mutes, and also to decide their nature and strength. Pollak endeavored to produce dizziness in a number of deaf-mutes by conducting a galvanic current through their heads. Several exhibited signs of dizziness, accom panied by movements of the head and eyes, also exhibited by normal subjects under like circumstances, while 29.3 per cent. were not affected in any way; in these, then, it was to be supposed that the semicircular canals were entirely de stroyed, and Pollak points out the resem blance between the figures thus obtained and the percentage of cases of entire ab sence or destruction of the semicircular canals found by post-mortem examina tion of deaf-mutes.
Although deaf-mutism brings with it a long train of indirect consequences, which are of great importance as affect ing the daily life of the deaf-mute, its more direct results are but few, and even these are the subject of dispute.