Hyperæsthesia.
DEFINITION.—Exalted sensibility of the larynx, not necessarily associated with pain or other disorders of function. This condition is rare, but it is nevertheless met with. We sometimes find that the larynx is abnormally sensitive to touch or to an irritant, even though there is no marked inflammation. The symptoms and history justify the consideration of the condition apart.
ETIOLOGY.—Predisposing causes are probably to be found in the general condition of the nervous system. Persons of a highly susceptible nervous organization are, other things being equal, more prone to this affection. Certain habits of life, such as confinement to the house or want of exercise in the open air, excessive use of the voice in singing, especially in unnatural keys or after unnatural methods, have seemed to me to predispose to the exaltation of the sensibility of the organ. It must be confessed, however, that so little is accurately known of the history of the disease that we are left in much doubt as to the rôle of these conditions in the production of the abnormal state. The exciting causes of hyperæsthesia of the larynx are the long-continued action of the predisposing causes—acute and chronic inflammation, mechanical and chemical irritants, etc. So far as my own experience goes, the use of the voice in an unnatural key, or perhaps rather the strain upon the parts by efforts to force the organ to perform the function of phonation in an abnormal manner, has more frequently been assigned by the patient as the cause than any other one thing. I have seen quite a number of singers who have by an effort of the muscles, apparently, produced an intensified irritability of the mucous surfaces. It is possible that in rare instances there may be an exalted activity of the receptive centres, and that the local trouble in the larynx is only a manifestation, in the distribution of the nerves, of the central disease. In such cases, however, the disorder should reach all the parts supplied by the pneumogastrics. Inflammation of the pharynx, soft palate, posterior nares, and perhaps of the structures of the ear, have an influence over the sensibility of the parts below, probably through the relations of the glosso-pharyngeal and other nerves to the laryngeal branches of the pneumogastrics. E. F. Ingals of Chicago has seen a case of laryngeal hyperæsthesia produced apparently by a varicose condition of the vessels about the base of the tongue. Frankel, Tornwaldt, Bayer, Schnitzler, A. H. Smith, Glasgow, and others have reported cases in which there were symptoms of hyperæsthesia or of reflex motor disturbances due to trouble in the nose or pharynx. The general health has much to do with the development of the local trouble. Asthenia is associated so frequently with hyperæsthesia of other parts that we should expect to find this relation also in the larynx.
SYMPTOMS.—The symptoms of hyperæsthesia of the larynx are in part involved in the definition of the affection—exalted susceptibility to the touch, intolerance to the presence of mechanical irritants, a sensation of discomfort in the presence of chemical agents, such as gases or impure air, and, when the exaltation is excessive, positive pain. This pain may be only a soreness or tenderness or it may amount to neuralgia. This last form of exaltation is rare. When present it has been considered a special disease and treated as a separate affection. Von Ziemssen and Mackenzie regard it as a variety of hyperæsthesia. Schnitzler, Jones, Wagner, and Mackenzie report cases. The pain is said to be not confined to the larynx, but to extend up toward the ear and along the course of the superior laryngeal nerve. In two cases observed by the writer the pain not only extended along the course of this nerve, but into the pharynx and posterior nares as well. In these cases the patients were both singers, and both had adopted with great enthusiasm a new method by which the abdominal muscles were brought into action at the expense of the muscles of the thorax. The pain was always aggravated by any effort to sing, but more especially by any return to the method noted. The pain not unfrequently extended to the face as well as to the ear.
Neuralgia of hysterical origin, according to Thaon,4 is more frequently met with on the left side than on the right. Instead of being general, it is not unfrequently limited to points or circumscribed patches.
4 Proceedings Laryng. Cong., Milan.
COURSE AND TERMINATION.—The course of the affection is very uncertain. In the neuralgic variety the pain may be transient, passing away in a few days or hours even, but generally there are frequent recurrences extending through weeks or months. Simple exaltation of the common sensibility is much more persistent and more uniform in its character.
Hyperæsthesia of the larynx is so largely dependent upon the general health that not only is it very irregular in its course and duration, but its termination is equally uncertain. It can hardly be said to be a cause of death, as it does not involve structures necessary to life. It disappears occasionally without treatment. When complicated with other affections, such as acute or chronic inflammation, alterations of the function of the pneumogastrics, with disease of the thoracic viscera or with general derangements of the nervous system, its course and termination must depend largely upon the persistence of these complications.
PATHOLOGY.—So far as the pathology and morbid anatomy have been studied, there is no appreciable change of structure. This is true, of course, only of those cases which are not complicated. Whether the primary lesion is in the mucous membrane, denuding, pinching, or otherwise modifying the terminal portions of the nervous filaments, or whether there is an alteration of the conducting portion of the sensory nerves, or, in fine, whether there is some lesion of the receptive centres, it is impossible in most instances to say. It is probable, however, that in some cases the first morbid fact has been an alteration in the nerves themselves. The cases induced by unnatural methods of using the vocal organs are apparently of this character.
The diagnosis, prognosis, and treatment will be considered in connection with Paræsthesia.