Polyps and nodules result from injury to the lamina propria of the true vocal cords. Granulomas result from injury to the perichondrium overlying the vocal processes of the arytenoid cartilages.
Vocal cord polyps may occur at the mid third of the membranous cords and are more often unilateral. Polyps tend to be larger and more protuberant than nodules and often have a dominant surface blood vessel. They frequently result from an initiating acute phonatory injury. Other polypoid changes, often bilateral, may have several other causes, including gastroesophageal reflux, untreated hypothyroid states, chronic laryngeal allergic reactions, or chronic inhalation of irritants, such as industrial fumes or cigarette smoke. Acute injury usually causes pedunculated polyps, whereas polypoid edema results from chronic irritation.
Vocal cord nodules usually occur bilaterally at the junction of the anterior and middle third of the cords. Their main cause is chronic voice abuse—yelling, shouting, singing loudly, or using an unnaturally low frequency.
Vocal cord granulomas occur in the posterior glottis adjacent to the vocal processes of the arytenoid cartilage. They can be bilateral or unilateral. They usually result from intubation trauma but may be aggravated by reflux disease.
(See also Overview of Laryngeal Disorders.)
Diagnosis of polyps, nodules, and granulomas is based on direct or indirect visualization of the larynx with a mirror or laryngoscope (see table Differentiating Vocal Polyps, Nodules, and Granulomas). Biopsy of discrete lesions to exclude carcinoma is done by microlaryngoscopy (see Laryngeal Cancer).
Differentiating Vocal Polyps, Nodules, and Granulomas
Correction of the underlying voice abuse cures most nodules and granulomas and prevents recurrence. Removal of the offending irritants (including treatment of any gastroesophageal reflux) allows healing and is necessary to prevent recurrence. Voice therapy with a speech therapist reduces the trauma to the vocal cords caused by improper singing or protracted loud speaking. Nodules usually regress with voice therapy alone. Granulomas that do not regress can be removed surgically but tend to recur.
Traumatic polyps must be surgically removed to restore a normal voice. Other polypoid lesions, often bilateral, arising from tobacco abuse or hypothyroid states, should initially receive medical management. Cold-knife microsurgical excision during direct microlaryngoscopy is preferable to laser excision, which is more likely to cause collateral thermal injury if improperly applied.
In microlaryngoscopy, an operating microscope is used to examine, biopsy, and operate on the larynx. Images can be recorded on video as well. The patient is anesthetized, and the airway is secured by high-pressure jet ventilation through the laryngoscope, endotracheal intubation, or, for an inadequate upper airway, tracheotomy. Because the microscope allows observation with magnification, tissue can be removed precisely and accurately, minimizing damage (possibly permanent) to the vocal mechanism. Laser surgery can be done through the optical system of the microscope to allow for precise cuts. Microlaryngoscopy is preferred for almost all laryngeal biopsies, for procedures involving benign tumors, and for many forms of phonosurgery.