SYMPTOMS AND DIAGNOSIS.--The main symptom is the peculiar, gradually increasing dyspnoea; once observed, it is recognized without much difficulty. There may also be mucous râles; cough rough and sibilant; attempts at clearing the throat without expectoration, or occasionally with some expectoration, which is at first light-colored, then streaked with blood, and at last purulent, but never abundant (unless accidentally complicated by catarrh), and always difficult to eject; perhaps occasional pain, but constant disagreeable sensation (tightness) in the trachea just above the sternum. Tracheoscopy settles the diagnosis. The tracheal rings are seen either as diminished circles or arcs--sometimes concentrically placed, sometimes in two different directions, as shown in a case of tracheal stenosis from {143} compression causing protrusion of the mucous membrane into the interior, represented in Fig. 32, or else constricting bands are visible. As to the dyspnoea, both inspiration and expiration are affected--frequently, however, the former more than the latter, as is shown by pneumatometry. The head is thrown forward and the chin up; the larynx moves up and down less energetically than in health (while the respiratory movements of the larynx are abnormally increased in laryngeal dyspnoea); the thorax is less expanded than normally, especially its upper portions. As to catheterization and probing, see the remarks under the head of Morbid Growths. PATHOLOGY.--The pathological changes in cases of stenosis vary with its cause. In the great majority of cases of stricture from within, syphilis--antecedent ulceration followed by cicatrization--has produced the stenosis; in compression thyroid disease, and next often aneurism, is the cause. The stenosis is most frequently situated in the lower, next in the upper, and least in the middle, portion; more often than the latter alone the whole tube is affected. PROGNOSIS.--This is rather favorable with timely and proper treatment unless a continuing active cause be irremovable; without treatment, however, the cases almost invariably terminate fatally from pneumonia, tracheal spasm, apnoea as before explained, etc. TREATMENT.--When the symptoms are urgent and the stenosis is not too low down, tracheotomy must be performed. Sometimes a very long and flexible tube may be introduced with success in case of very low stenosis, but more often tracheotomy is disappointing on account of the stenosis extending too low down even when its beginning is higher up. Stricture, especially when the symptoms are not very urgent, may be relieved by dilatation through the natural passages, with, or if possible without, previous tracheotomy. The cure of compression implies removal of the compressing tumor or disease. Soothing inhalations, such as of hops, benzoin, etc., diminish irritation and give temporary relief. DILATATION (HERNIA, FISTULE).