The tendency of aurists is, I believe, to explain the phenomena by either direct influence propagated as sound-waves through the auditory apparatus to the labyrinth, or by admitting inhibitory impressions affecting the vaso-motor loops and causing increased pressure in the semicircular canals. I am disposed to think that the effect may be a more direct one, and to regard the centres as directly influenced through the fifth nerve, including vaso-motor phenomena of course—a question to be, however, easily solved in the laboratory.
In this form of vertigo tinnitus is slight or transient, coming and going, or if permanent but faintly felt.
Middle-ear vertigo may arise from any inflammation of the part or from closure of the Eustachian canal. There are then direct mechanical influences affecting the labyrinth, as well as sensory irritations, not causing auditory phenomena; whilst also the inner ear is apt soon to suffer from direct propagation of inflammatory processes. There is then paroxysmal vertigo, variable hearing,4 and early tinnitus.
4 Burnett, Sect. Otol., Int. Med. Cong. Proc., 1876.
Inner-ear vertigo seems to be due to irritations, auditory, mechanical, or inflammatory—whatever disturbs seriously the nerves of the semicircular canals, since, if we may trust recent research,5 the cochlea is not a source of vertiginous impressions. This form of vertigo was first described with pathological proof by Menière in 1860, and is probably in its variety of degrees the most common of all the origins of dizziness.
5 Gellé.
The acute attack is nearly always preceded by more or less deafness, and in many cases by middle-ear catarrh,6 with or without tinnitus. More rarely all the symptoms arise abruptly. There are sudden tinnitus, deafness, nausea, vertigo. The loss of hearing remains, and is variable, or, finally, the hearing is lost altogether. The tinnitus is permanent or varies in amount, but as the deafness grows complete the vertigo disappears, and although cases of death have been described, labyrinthine vertigo is, as a rule, prone to get well in time.
6 Burnett.
Single attacks are rare. It is apt to repeat itself, and finally to cause all the distressing cerebral symptoms which characterize the worst gastric vertigo, and at last to be capable of easy reproduction by light, heat, over-exertion, and use of the mind or eyes, by emotion, or by gastric disorder.
Even after the vertigo has ceased to exist the fear of loss of balance remains, while perhaps for years the sense of confusion during mental effort continues, and gives to the sufferer a feeling of what a patient described to me as mental vertigo—some feeling of confusion, lack of power to concentrate attention, loss of hold on trains of thought, with now and then a sensation as if the contents of the cranium moved up or down or swayed to and fro.