Laryngeal disease causing voice disorders

Vocal nodules

These are known as singers’ nodules in adults and screamers nodules in children (Fig. 43.44). They are fibrous thickenings of the vocal folds at the junction of the middle and anterior third, and are the result of vocal abuse. Speech therapy is therefore the preferred treatment and the lesions will resolve spontaneously in most cases. Occasionally the nodules will need to be surgically removed using modern microlaryngoscopic dissection or laser techniques. Follow-up by the speech therapist is necessary until all of the underlying errors in voice production are overcome.

Vocal fold polyps

These are usually unilateral and may be associated with an acute infective episode, cigarette smoking and vocal abuse

Laryngeal papillomata

These occur mainly in children but can also present in adults. They are most commonly found on the vocal folds but may spread throughout the larynx and tracheobronchial airway (Fig. 43.46). They are caused by papilloma viruses and need removal by laser surgery in order to maintain a rea­sonable voice and airway. Antiviral treatment by such drugs as interferon remains of doubtful value at present. Endo­scopic laser surgery is the least traumatic way of removing these lesions and should not produce scarring or cause implantation of the papillomata elsewhere in the airway.

Acute laryngitis

This often occurs in association with upper respiratory tract infections in association with a cough and pharyngitis. It may, however, be localised to the larynx, is usually viral and settles quickly if the patient rests the voice during the active inflam­mation. Steam inhalations are soothing along with mild analgesics but antibiotics are unnecessary. The condition should resolve in 2—3 weeks with voice care. Hoarseness lasting for 3—4 weeks should always be referred for an ENT opinion, particularly in smokers.

Chronic laryngitis

Chronic laryngitis may be specific and can be caused by mycobacteria, syphilis and fungi. Treatment is directed towards the causative organism. Nonspecific laryngitis is common, and the main predisposing factors are smoking, chronic upper and lower respiratory sepsis and voice abuse. In some cases the laryngeal mucosa may become dysplastic, particularly over the true vocal folds, and is a premalignant condition. It may require microlaryngoscopic examination and biopsy. Treatment is by the elimination of any predis­posing factors, particularly smoking, and attention to any vocal abuse under the guidance of a speech therapist. Diagnosis of chronic laryngitis should not he made unless the larynx has been fully evaluated by a laryngologist.

Vocal fold palsy

This may be unilateral or bilateral, but a unilateral left vocal fold palsy is the commonest as a consequence of the long intrathoracic course of the left recurrent laryngeal nerve which arches around the aorta and may be commonly involved in inflammatory and neoplastic conditions involving the left hilum (Fig. 43.47). Lung cancer is the commonest single cancer in many parts of the world and a left vocal fold palsy should be considered to be due to a carcinoma of the lung until proved otherwise. Other malignant lesions can cause a similar effect and may arise in the nasopharynx, thyroid gland or oesophagus. Bilateral vocal fold paralysis is uncommon and tends to occur after thyroid surgery or head injuries (Table 43.12).

Clinical features

Unilateral recurrent laryngeal nerve palsy of sudden onset produces hoarseness which is most notable for lack of volume to the voice and occasionally may be associated with difficulty in swallowing liquids and weakening of the cough. These symptoms may be short lived and the voice may return to normal within a few weeks as the muscles in the opposite vocal fold compensate and move it across the midline to meet the paralysed vocal fold which usually lies in the paramedian position. Owing to this efficient compensation, in slowly progressive lesions the patient may only experience slight weakness of the voice with prolonged use.

Bilateral recurrent laryngeal nerve palsy is an occasional and very serious complication of thyroidectomy. Acute dyspnoea occurs as a result of the paramedian position of both vocal folds which reduce the airway to 2—3 mm and which tend to get sucked together on inspiration. In severe cases tracheostomy or intubation is necessary immediately otherwise death occurs from asphyxia.

Investigation of vocal fold paralysis is most easily encompassed nowadays by a CT scan from skull base to diaphragm. This technique has replaced the multiple previous investiga­tions which were necessary and reveals most of the pathology which may give rise to an undiagnosed vocal fold palsy. Approximately 20—25 per cent of cases of vocal fold paralysis occurs without known pathology and spontaneous recovery may occur. In unilateral vocal fold paralysis, where compensation does nor occur, the paralysed fold may be medialised by injecting Teflon paste lateral to the vocal fold and displacing it medially. Alternatively, a small external operation on the thyroid cartilage may be undertaken in order to enter the paraglotric space and displace the fold medially (thyroplasty). These surgical procedures should be performed early if the cause is carcinoma of the bronchus and the outlook of the patient is poor. When the pathology is unknown it may be better to wait for a period of 1 year to see whether spontaneous improvement occurs and to allow further recovery with the help of speech therapy.

In bilateral vocal fold paralysis the patients frequently require tracheostomy, but surgery may be carried out to remove a small portion of the posterior aspect of one vocal fold or a portion of one arytenoid cartilage. These proce­dures are most easily performed endoscopically with a car­bon dioxide laser. They increase the size of the posterior glottic airway allowing the patient to be decannulated or even to avoid a tracheostomy in the first place. Some laryngologists have advocated reinnervation procedures for the paralysed larynx by rotating a nerve muscle combination into the larynx from the neck. However, these techniques have not yet found widespread acceptance.

Tumours of the larynx

Benign tumours of the larynx are extremely rare and squamous carcinoma of the larynx predominates over all others, being responsible for more than 90 per cent of tumours within the larynx. It is the commonest head and neck cancer and almost always occurs in elderly male smokers. However, over the past two decades the sex incidence has changed as a consequence of increasing smoking amongst women, and in some areas they now make up more than 20 per cent of the patients. The squamous epithelium of the vocal folds and the respiratory epithelium of the supraglottis undergo dysplastic change stimulated by cigarette smoking and other factors. The incidence of laryngeal cancer in the three compartments supraglottis, glottis and subglottis varies around the world; the glottis is generally the commonest site followed by the supraglottis (Fig. 43.48). True carcinomas of the subglottis are very rare and most are a consequence of inferior spread from the glottis.

Clinical features

The frequent glottic origin means that patients almost always present with hoarseness. This is of great importance because if a diagnosis can be made while the tumour is in the first stage, i.e. confined only to one vocal fold, these cancers have more than a 90 per cent 5-year disease-free cure rare when treated with radiotherapy alone. The cure rare drops dramatically once the lymphatically rich supraglottis or subglottis is involved, owing to spread to neck nodes. The appearance of more than one neck gland halves the overall prognosis of the patient.

Investigations

Direct laryngoscopy, preferably a microlaryngoscopy, together with Hopkin’s rod examination allows precise determination of the extent of the tumour and biopsy con­firms an exact histology (Table 43.13). CT and MRI scanning give further details of the extent of larger tumours demonstrating escape of the tumour outside the larynx and suspicious nodal involvement within the neck which may nor be determined on clinical examination.

Treatment

Early supraglottic and glottic tumours stages I and II are optimally treated with megavoltage radiotherapy where these facilities exist. Five-year cure rates for stages I and II are   approximately 90 and 70 per cent, respectively, and the patient has an excellent voice following this type of treat­ment. If modern megavoltage radiotherapy is not available then early tumours may be excised by means of endoscopic laser surgery or open partial laryngeal surgery. This latter may be in the form of a laryngofissure when the thyroid cartilage is opened anteriorly in the midline and the squamous carcinoma excised under direct vision from the vocal fold or supraglottis or, in the case of more extensive unilateral glottic and supraglottic growths, a vertical hemilaryngectomy may be undertaken. This leaves a defect on one side of the larynx which is usually reconstructed with adjacent strap muscles. With early bilateral supraglottic tumours a horizontal laryngectomy may be undertaken excising the supraglottic growth and the remainder of the glottis. The subglottic part of the larynx is then stitched to the tongue base to provide continuity. In most patients undergoing partial laryngeal surgery of this type the voice result is not as satisfactory as that with radiotherapy, although the cure rates are often comparable.

Advanced laryngeal disease

Once the squamous carcinoma has caused fixation of the vocal fold or has infiltrated outside the larynx into adjacent structures such as the thyroid gland and strap muscles, some form of subtotal or total laryngectomy is required to attempt to cure the disease. Total laryngectomy is frequently required when radiotherapy fails (Figs 43.49-43.51). After the larynx has been removed, the remaining trachea is brought out on to the lower part of the neck as a permanent tracheal stoma and the hypopharynx, which is opened at the rime of the operation, is closed to restore the continuity for swallowing. Thus, the upper aerodigestive and digestive tracts are permanently disconnected. Part or all of the thyroid gland and associated parathyroid glands may also need to be removed depending on the extent of the disease, so patients after this type of radical surgery may require oral thyroxine and calcium supplements for the remainder of their lives. Laryngectomy patients must obviously avoid immersion in water as this would flow straight into their tracheal stoma. However, a rather complex form of snorkle device has been developed to allow laryngectomy patients to go swimming and simple protection of the stoma with a towel may allow them to take a careful shower.

Vocal rehabilitation

The loss of the larynx as a generator of sound does not prevent patients speaking as long as an alternative source of vibrating can be created in the pharynx. There are basically three ways of achieving this.

An artificial device which produces sound when applied to the soft tissues of the neck which is turned into speech by the vocal tract comprising the tongue, the pharynx, oral cavity, lips, teeth and nasal sinuses. These devices are usually battery powered.

Voice production may be restored in some patients by learning to swallow air into the pharynx and upper oesophagus. On regurgitating the air, a segment of the pharyngo-oesophageal mucosa vibrates to produce sound which is once again modified by the vocal tract into speech (Fig. 43.52).

The most modern method is to gain use of the expired air from the lungs to power speech which is achieved by plac­ing a small valve through the back wall of the tracheal stoma into the pharynx. This is a one-way valve allowing air from the trachea to pass into the pharynx but it does not allow food and liquid to pass into the airway (Fig. 43.53).

There is a variety of these type of valves, the best known being the Blom—Singer valve which was developed in the USA. With the restoration of expired air passing into the pharynx, the segment of vibrating pharyngeal mucosa has a much greater quantity of air than when it is simply swallow­ed into the pharynx and oesophagus, and this gives an improved flow and quality to the speech of total laryngectomy patients. These valves are common nowadays in laryn­gectomy patients in many countries and they must not be confused with tracheostomy tubes. Like all foreign bodies, the speaking valves are associated with minor complications such as the formation of granulations, bleeding or leakage of pharyngeal contents.