The human larynx plays a pivotal role in airway protection, respiration, and phonation. Most patients with benign laryngeal disorders present with dysphonia. These disorders are particularly prevalent in individuals who use their voices professionally. Malignant neoplastic disease should be excluded as an underlying cause of voice problems: Every patient who presents with dysphonia should undergo a thorough head and neck examination. Once it is established that there is no evidence of malignancy, patients can be treated appropriately, ideally within a voice clinic. A properly equipped voice clinic must have access to video-laryngeo-stroboscopy and be conducted with a suitably qualified speech therapist.

The diagnosis should include a thorough appreciation of the patient’s lifestyle and occupational habits as well as a detailed examination of the vocal folds including stroboscopy. Most benign laryngeal lesions are treatable with a combination of surgery and speech therapy, but measures to prevent the recurrence of disease by instigating and maintaining lifestyle changes are also necessary.

The larynx consists of a cartilaginous framework comprising the single thyroid, cricoid, and epiglottic cartilages and the paired arytenoid, corniculate, and cuneiform cartilages. The larynx is suspended from the hyoid bone by the thyrohyoid membrane. The vocal folds run from the angle formed by the thyroid lamina anteriorly to the vocal process of the arytenoid cartilages posteriorly. Alteration in the position and length of the vocal folds is primarily the result of movement of the synovial cricoarytenoid joints, with a contribution from movement of the cricothyroid joints. Above the vocal folds run the false cords, formed by the medial border of the aryepiglottic folds. These are separated from the vocal folds by horizontal sinus known as the laryngeal ventricle, which contains numerous mucin-secreting glands.

The vocal folds are covered with a stratified squamous epithelium that has up to 20 layers; this epithelium covers the lamina propria, which has three layers, beneath which lies the vocal ligament and vocalis muscle. Loose collagen cross-linkages between the epithelium and the superior layer of the lamina propria (ie, Reinke space) allow oscillation of the mucosal wave during phonation as the epithelium is able to glide over Reinke space.

Sound is produced following creation of subglottic pressure as expiration occurs against a closed glottis. As air passes between the adducted vocal folds, the Bernoulli effect causes vibration of the mucosa of the vocal folds, producing sound. Abnormalities preventing full adduction of the vocal folds or directly interfering in vibration of the mucosa produce dysphonia.

Patient History

The onset, duration, and progression of any voice change should be ascertained. Any preceding upper respiratory tract infections, direct or vocal trauma, or endotracheal intubation should be noted. Persistent, progressive dysphonia in a smoker must always raise the possibility of malignant disease, particularly if associated with dysphagia or odynophagia.

A key consideration is the patient’s age. Adults have a greater incidence of malignant disease, whereas in children who are hoarse the chief differential diagnosis is between vocal cord nodules and juvenile papillomatosis. An occupational history is of particular relevance because the voice disorder may be secondary to the pattern of voice use or working conditions. A history of previous surgery is essential, as is documenting any previous laryngeal treatment or speech therapy. Additional patient history questions should include (1) smoking habits; (2) fluid intake, including caffeine and alcohol intake; and (3) symptoms of nasal allergy or sinusitis. Direct questioning should assess the presence of symptoms suggestive of gastroesophageal (or laryngopharyngeal) reflux, and hypothyroidism.

Patient Examination

The patient examination should include a full ear, nose, and throat (ENT) exam, including a conventional inspection of the larynx followed by a more detailed evaluation of vocal fold movement using video stroboscopy.

A full ENT examination is performed, including mirror indirect laryngoscopy. This guides the chances of successfully performing rigid laryngoscopy and often makes the diagnosis. The two alternative methods, which allow photodocumentation and a more leisurely view, are flexible nasolaryngoscopy, or rigid endoscopy, using a 70° or a 90° endoscope. In both techniques, stroboscopic light may be used to identify defects of the mucosal wave.

Nasolaryngoscopy allows thorough inspection of the nose, postnasal space, pharynx, and larynx in a physiologic position. Rigid endoscopy, conducted via the oropharynx, offers the most detailed view of the larynx in the compliant patient. Both methods can use video systems for photodocumentation: Visualization of the larynx by patients significantly improves understanding and compliance with speech therapy.

Figure 30–1 illustrates the characteristic appearances of some common benign laryngeal lesions.

Videostroboscopy

Videostroboscopy is an important tool in monitoring rehabilitation and providing feedback during speech therapy. It is also useful in the diagnosis of lesions such as intracordal cysts and in differentiating these lesions from vocal cord nodules.

Stroboscopic examination allows visualization of the mucosal wave occurring at the medial edge of the vocal fold, the appearance being one of a “slow motion” film. This appearance is created by the flickering stroboscopic light illuminating consecutive mucosal waves at a similar point in the wave form. The frequency of stroboscopic illumination differs slightly from the frequency of the mucosal wave, creating the perception of a slowly moving mucosal wave. This effect is lost if pathology results in a mucosal wave lacking a consistent periodicity. High-speed video recording now allows direct visualization of the mucosal wave, rather than the perception of visualizing the wave created by stroboscopy. This technique has some advantages; however, it requires greatly slowed playback and therefore does not allow “live” images, which are particularly helpful in patients’ understanding of their pathology.

Phonotrauma

Pathogenesis

Most vocal cord nodules, polyps, and the condition known as Reinke edema arise as a result of repetitive trauma to the vocal cords, which is known as phonotrauma, and is associated with a local inflammatory response. Shear forces occur during phonation at the area of maximal wave amplitude, which is the border of the anterior and middle third of the vocal fold. Hence, vocal pathology secondary to phonotrauma tends to occur at this site.

Vocal Cord Nodules

Essentials of Diagnosis

• Usually affects children or individuals who use their voices professionally.
  
• History of voice abuse common, such as frequent shouting in a young child.
  
• Bilateral, pale lesions at the junction of the anterior one third and posterior two thirds of the vocal cords.

General Considerations