APHO'NIA (Gk. dcpwsta, from d, a, priv. cpws7'2, phone, voice, sound). The term used in medicine to signify a more or less complete loss of voice.' It is altogether distinct from mutismn, in which it is impossible to form articulate sounds, and in most eases the voice is not en tirely gone, but only more or less lost or sup pressed. The voice is essentially produced by three distinct agents—viz. (1) the expiration of air, (2) the opening of the glottis, and (3) the tension of the vocal cords; and hence anything interfering with expiration, or with the func tions of the glottis and vocal cords, may cause aphonia. Thus, it may result from paralysis of the respiratory muscles, from pulmonary emphy sema, and sometimes from pneumonia; or it may he caused by diseases of the larynx. as chronic laryngitis, of the glottis, polypus, etc.; or by pressure on the larynx caused by abscesses, vegetations. and any kind of morbid growth; or it may he traced to sonic functional or organic disturbance of the inferior vocal cords. Thus, the muscular fibres which act on these cords may become affected in acute laryngitis by extension of the inflammation, or their action may be im peded by the pressure of false membrane in croup. Again, in eases of lead or phosphorus poisoning, there is aphonia due to fatty degen eration of the muscles. Not infrequently aph onia may be traced to compression of the re current or inferior laryngeal nerve, which is the nerve-supplying mator power to all the muscles of the larynx, with one trifling exception. Such
pressure is not infrequently caused by aneurism, abscess, tumor, etc. In the same way, a wound or contusion of the pneumogastrie nerve, or one of the recurrent branches, will cause aphonia or, more commonly, an extremely hoarse modifica tion of the voice, in consequence of the laryngeal muscles being paralyzed on one side and re maining active on the other. There are cases of direct nervous action being interfered with ; but there are ninny cases of what may be termed reflex aphonia, as when the voice is often more or less lost in the course of pregnancy when ac companied by convulsions, or in consequence of the presence of intestinal worms, or after the rapid suppression of an exanthematous rash. or of a long - continued hemorrhagic discharge. Aphonia is. moreover, very commonly associated with hysteria.
When aphonia is not due to irremovable causes, as tumors, fatty degeneration of the lar yngeal muscles, etc., it generally disappears after bn interval. It occasionally assumes remarkable intermittent shapes.
In those cases which are amenable to treat ment, emetics, electricity, strychnine. leeching, blistering and local application of nitrate of silver, have been found to be the most useful remedies.