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4 Larynx and Hypopharynx
4.1 Larynx—Applied Anatomy and Physiology
4.1.1 Basic Anatomy and Physiology
4.1.1.1 Embryology
The larynx develops from a two-part anlage: the supraglottis develops from a buccopharyngeal bud, and the glottis and subglottis from a tracheobronchial bud. This is clinically significant in the postnatal period. The nerves of the pharyngeal arches are branches of the vagus nerve.
During the course of life, the larynx descends from about the level of the second vertebra at birth, depending on the sex, to about the level of the fifth cervical vertebra in the adult.
4.1.1.2 Anatomy
The laryngeal skeleton consists of the thyroid, cricoid, and arytenoid cartilages, which are hyaline cartilage; the epiglottis, which is fibrous cartilage; and the fibroelastic accessory cartilages of Santorini (corniculate cartilage) and Wrisberg (cuneiform cartilage), which have no function.
Calcification and ossification of the thyroid cartilage begin at the time of puberty. Ossification of the cricoid and arytenoid cartilage follows somewhat later. The female larynx calcifies later than that of the male. On radiography, it is often difficult to distinguish the calcified parts of the laryngeal framework from bony foreign bodies.
Internal and external ligaments and membranes connect the cartilages and stabilize the covering soft tissue.
For clinical purposes, the laryngeal cavity is divided into three compartments ( ▶ Fig. 4.1 and ▶ Table 4.1 ):
Fig. 4.1 Compartments and individual structures in the larynx. 1, The aryepiglottic fold, forming the boundary between the larynx and the hypopharynx; 2, the piriform sinus, which belongs to the hypopharynx; 3, vocal ligament; 4, anterior commissure; 5, thyroid cartilage; 6, cricoid cartilage; 7, thyroid gland; 8, trachea.
Fig. 4.2 (a) A three-dimensional section through the membranous part of the vocal fold, magnified from the frontal section through the larynx as shown in the inset in the lower left corner. 1, Stratified squamous epithelium; 2a, superficial layer of the lamina propria; 2b, intermediate layer of the lamina propria; 2c, deep layer of the lamina propria, 2b and 2c forming the vocal ligament; 3, vocal ligament enveloping the vocalis muscle; 3a, superior arcuate line; 3b, inferior arcuate line; 4a, medial part of the thyroarytenoid muscle (i.„e., the vocalis muscle); 4b, lateral part of the thyroarytenoid muscle; 5, epithelium of the laryngeal ventricle (Morgagni ventricle), consisting of cylindrical ciliated epithelium and islets of squamous epithelial cells; 6, subglottic respiratory cylindrical ciliated epithelial zone; 7, mucous gland. (b) Enlarged schematic drawing of the lamina propria. The numbers correspond with those in (a).
Supraglottic space | Epilarynx | Laryngeal surface of the epiglottis + aryepiglottic fold + arytenoid |
Vestibule | Between the epiglottis and the rima glottidis | |
Aditus | Epilarynx + vestibule | |
Glottal space | Vocal folds and 1 cm inferiorly | |
Subglottic space | Down to the lower border of the cricoid cartilage | |
“Transglottic space” | Glottis + ventricle + vestibular folds | |
Supraglottis.
Glottis.
Subglottis.
The vocal fold has a cartilaginous part, which is the arytenoid cartilage, and a membranous part. The latter includes the vocalis muscle, the lamina propria, and the epithelium ( ▶ Fig. 4.2). The length of the membranous part of the vocal fold is 0.3 cm in the newborn, 1.0 to 1.4 cm in women, and 1.5 to 2.0 cm in men. The glottis is the space between the free edges of the vocal folds. The transglottic space is illustrated in ▶ Fig. 4.1 and described in ▶ Table 4.1 (see also ▶ Fig. 4.13).
Note: Carcinoma occurs almost exclusively in the intermembranous part of the glottis, whereas intubation granuloma and contact granuloma caused by vocal overuse mainly affect the intercartilaginous part (see also ▶ pp. 342 and ▶ 343 and ▶ Fig. 4.19 and ▶ Fig. 4.20).
Superiorly, the larynx is limited by the free edge of the epiglottis, the aryepiglottic fold, and the interarytenoid notch. Inferiorly, the lower edge of the cricoid cartilage marks the junction with the trachea (see also ▶ Fig. 4.1).
The thyroid cartilage is united by a joint with the cricoid cartilage. Rocking and slight gliding movements occur at this joint. The muscles, ligaments, and membranes between the cartilages allow functionally important movements between different parts of the larynx.
External ligaments and connective-tissue membranes anchor the larynx to the surrounding structures. The most important membranes include the following:
The thyrohyoid membrane holds the opening for the superior laryngeal artery and vein and for the internal branch of the superior laryngeal nerve, which provides the sensory supply to the larynx above the vocal folds.
The cricothyroid membrane is the point where the airway comes closest to the skin; this is the site for laryngotomy (see also Fig. 6.15).
The cricotracheal ligament provides attachment to the trachea.
The internal ligaments and connective-tissue membranes (e.g., the conus elasticus and thyroepiglottic ligament) connect the cartilaginous parts of the larynx to each other.
The internal muscles and the one external muscle act synergistically and antagonistically to control the functions of the larynx. They open and close the glottis and place the vocal folds under tension ( ▶ Fig. 4.3). This interplay explains the different positions of the vocal folds in paralysis of the recurrent laryngeal nerve or of the external branch of the superior laryngeal nerve ( ▶ Table 4.2 ).
Fig. 4.3 Directions of pull in the laryngeal musculature. 1, Cricothyroid muscle (the anticus muscle)—tenses the vocal folds; 2, medial part of the thyroarytenoid muscle (the vocalis muscle); 3, lateral part of the thyroarytenoid muscle; 2 and 3 close the glottis (dotted lines and pale colors) and add tension to the vocal folds; 4, lateral cricoarytenoid muscle (lateralis muscle)—moves the arytenoid cartilages in the direction of the dotted arrows: the vocal processes converge leaving an open triangle in the cartilaginous part; 5, interarytenoid or transverse muscle—acts synergistically to 2 and 3; 6, posterior cricoarytenoid muscle (posticus muscle)—the only opener.
Function | Muscle |
Opening of the glottis, abduction of the vocal folds | Posterior cricoarytenoid muscle (posticus muscle) |
Closure of the glottis, adduction of the vocal folds | Lateral cricoarytenoid muscle |
Transverse and oblique arytenoid muscle | |
Thyroarytenoid muscle, lateral part | |
Tension of the vocal folds | (Anterior) cricothyroid muscle |
Thyroarytenoid muscle, medial part (vocalis muscle) |
Note: There is only one muscle that opens the glottis, the posterior cricoarytenoid. The muscles that close it are clearly in the majority. The ratio of their relative power is 1:3. Only the interarytenoid muscle, with a pars obliqua and a pars transversa, is unpaired; all other muscles are paired.
Nerve supply: The nerve supply of the larynx is bilateral, from the superior laryngeal and recurrent laryngeal nerves, which both arise from the vagus nerve (see also ▶ Fig. 4.11).
The superior laryngeal nerve divides into a sensory internal branch, which supplies the interior of the larynx down into the glottis, and an external branch, which provides the motor supply to the external cricothyroid muscle.
The recurrent laryngeal nerve provides motor supply to the rest of the ipsilateral internal laryngeal musculature and to the contralateral interarytenoid muscle. In addition, it provides sensation to the laryngeal mucosa inferior to the glottic cleft.
The left recurrent laryngeal nerve loops around the aortic arch to reach the larynx in the groove between the trachea and the esophagus. The right recurrent laryngeal nerve passes around the subclavian artery and then runs upward between the trachea and the esophagus.
Both recurrent laryngeal nerves enter the larynx at the inferior horn of the thyroid cartilage. The relations of this nerve to the inferior thyroid artery and thyroid gland are important in surgical anatomy (see also Chapter 4.3.2 Organic Functional Disorders).
When one is diagnosing paralysis of the recurrent laryngeal nerve (see also ▶ Fig. 4.11), pathology should be sought from the skull base around the jugular foramen, along the cervical course of the nerve, and within the chest and mediastinum. Causes of recurrent paralysis include metastases, malignant lymphoma, malignant goiter, esophageal carcinoma, tuberculous lymphadenopathy, aortic and carotid aneurysms, and pulmonary hypertension.
Blood supply: The blood supply to the larynx is divided by the glottis into two areas.
The supraglottic blood supply from the superior laryngeal artery originates from the external carotid artery. The inferior laryngeal artery is a branch of the inferior thyroid artery that derives from the thyrocervical trunk of the subclavian artery. It supplies the subglottis.
Venous drainage passes superiorly via the superior thyroid vein to the internal jugular vein and inferiorly via the inferior thyroid vein to the left brachiocephalic vein.
Lymphatic drainage: The lymphatic drainage of the larynx ( ▶ Fig. 4.4) is very important clinically.
Fig. 4.4 The glottal lymph barrier, which produces supraglottic and subglottic lymph flow. The first supraglottic lymph-node stations are the inconstant prelaryngeal node and the upper deep cervical nodes. The first subglottic node stations are the pretracheal and paratracheal and lower deep jugular lymph nodes. 1, Glottal lymph barrier; 2, internal jugular vein.
The free margin of the vocal fold has no lymphatic capillaries. The superior surface of the vocal fold and the floor of the ventricle have several lymphatic vessels running parallel to the free margin of the vocal fold.
On the other hand, the supraglottic space has a rich lymphatic network. A very dense and partly multilayered capillary network is found in the ventricular fold and ventricle. The supraglottic lymphatic pathway converges on the anterior insertion of the aryepiglottic fold and leaves in smaller collections of vessels along the neurovascular bundle of the larynx. Submucous and pre-epiglottic horizontal anastomoses are found in the midline of the larynx and are responsible for bilateral and contralateral metastases in carcinoma.
Between the free margin of the vocal fold and the upper border of the cricoid cartilage, the cranial margin of the subglottic region, lies the inferior surface of the vocal fold. It carries lymphatic capillaries. The posterior commissure serves as an important interconnection site for lymphatic capillaries between the various regions of the larynx.
The subglottic capillary network is not as dense as the supraglottic network. Bilateral and contralateral invasion of the lymph nodes is possible via the pretracheal and paratracheal lymph nodes. The additional drainage to the peritracheal and mediastinal lymph nodes is clinically important.
The laryngeal lymph is ultimately collected into the superior and inferior deep cervical lymph nodes.
Mucosal lining: The mucosal lining of the larynx is adapted to its special position at the junction of the respiratory and digestive tracts. Stratified squamous epithelium, partly keratinized, covers the laryngeal surface of the epiglottis, the vestibular folds, the vestibule of the larynx, and the vocal folds. Ciliated columnar epithelium covers the remaining parts of the mucosal surface.
The lamina propria has three layers. The deep and intermediate layers form the vocal ligament, and the superficial layer is also known as the Reinke space. This is a closed cleft beneath the epithelium of the vocal fold, with no glands or lymphatic capillaries. It is clinically important in relation to Reinke edema (see ▶ p. 352).
4.1.1.3 Physiology
Phonation: The larynx can only form a sound when the vocal folds vibrate. Together with the covering epithelium, the lamina propria is essential for voice production. The sound is modified by the movements of the pharynx, palate, tongue, and lips to form speech.
Vocal function, vocal range, tone amplification, timbre, and resonance are described in Chapter 5.1.2 Voice Diagnosis.
Hoarseness is the result of noise formed by endolaryngeal turbulence in the airstream and irregularities in the normally periodic vibrations of the vocal folds.
Respiration: The vocal folds are in the respiratory position; the glottis is open and is under reflex control, which depends on gas exchange and acid-base balance.
The sphincter function is the oldest phylogenetic function of the larynx ( ▶ Table 4.3 ).
Phonation | |
Respiration | |
Protection of the lower airway | Closure of the aditus on swallowing |
Closure of the glottis | |
Reflex respiratory arrest | |
Cough reflex | |
Glottal closure with thoracic fixation and Valsalva maneuver, as occurs when lifting heavy loads | |
Protection of the lower respiratory tract: The base of the tongue, posterior pharyngeal wall, and faucial pillars are involved in swallowing. The swallowing reflex, transmitted in the glossopharyngeal nerve, ensures cessation of respiration and contraction of the aryepiglottic folds, vocal folds, and vestibular folds, and tilting of the epiglottis by the thyroepiglottic muscle. Simultaneously, the suprahyoid musculature contracts, drawing the larynx anteriorly and superiorly by 2 to 3 cm.
Experience with surgical removal of the epiglottis shows that this structure is only of limited significance for protecting the larynx. An intact sensory nerve supply to the mucosa of the laryngeal aditus from the internal branch of the superior laryngeal nerve is much more important. It controls reflex muscular contraction.
The cough reflex is stimulated by particles of food touching the vestibular folds or penetrating through the larynx. It consists of a deep reflex inspiration with the larynx open. The glottis closes with rising intrathoracic pressure and then opens suddenly with an explosive expiratory stream, and the foreign body is coughed out.
Note: The larynx is a receptor field for other vasovagal reflexes. Mechanical irritation of the internal surface of the larynx can induce arrhythmia, bradycardia, and cardiac arrest. Satisfactory mucosal anesthesia must be ensured during endolaryngeal procedures. Particular care is necessary during repeated attempts at intubation, prolonged laryngoscopy, and laryngotracheal obstruction by foreign bodies, etc.
The vagal reflex can be blocked by atropine and increased by opiates. Reflex irritability is increased in smokers.
Thoracic fixation: The respiratory system is closed off by the glottis to provide mechanical assistance during several bodily functions—notably coughing, defecation, micturition, vomiting, and parturition. In addition, the pectoral muscles are supplemented during chin-ups, while digging, and in breathing during asthma attacks.
4.2 Methods of Examination
Examinations provide information about:
The position of the larynx and its relation to neighboring anatomic structures in the neck.
The external and internal shape of the larynx.
The type, site, and extent of lesions inside and outside of the larynx.
Functional disorders.
4.2.1 Inspection
Normally, the thyroid prominence can only be seen in men. It moves upward on swallowing; absence of this movement indicates fixation of the larynx by infection or tumor.
Retraction of the suprasternal notch on inspiration, combined with inspiratory stridor, suggests laryngotracheal obstruction by a foreign body, tumor, edema, etc.
4.2.2 Palpation
The laryngeal skeleton and neighboring structures are palpated during respiration and swallowing, with attention being paid to the following:
The thyroid cartilage.
The cricothyroid membrane and cricoid cartilage.
The carotid artery with the carotid bulb, which must not be confused with neighboring cervical lymph nodes; the palpating finger picks up pulsations.
The thyroid gland, lying inferior and lateral to the thyroid and cricoid cartilages.
Simultaneous movement of the larynx and thyroid gland on swallowing.
4.2.3 Laryngoscopy
The two ways of examining the larynx are indirect and direct laryngoscopy. The larynx is inspected with the aid of a mirror and the unaided eye, with a flexible or rigid endoscope, or with a laryngoscope and a microscope ( ▶ Table 4.4 ). Flexible nasendoscopy, like rigid endoscopy, enables high-quality imaging and photodocumentation. Mirror examination is described here for completion, as a flexible or rigid endoscope with video coupling may not always be available.
Oropharynx | Base of tongue, both valleculae epiglotticae, lingual surface of the epiglottis |
Hypopharynx | Piriform sinus |
Boundaries between the hypopharynx and larynx | Glossoepiglottic and aryepiglottic folds |
Larynx | Epiglottis, arytenoid cartilages, vestibular folds, vocal folds, and ventricles |
Subglottis |
4.2.3.1 Indirect Laryngoscopy
The examination technique is illustrated in ▶ Fig. 4.5. The tongue is grasped with the thumb and middle finger of the left hand, so that the thumb lies on top of the tongue with the middle finger positioned below. The index finger of the left hand is used to push back the upper lip. The tongue must be drawn forward carefully to prevent damage to the frenulum by the lower teeth. The light from the mirror is directed toward the uvula. The glass surface of the laryngeal mirror is warmed, and its temperature is tested with the examiner’s own hand. It is then introduced along the palate until it reaches the uvula.
Fig. 4.5 (a, b) Indirect laryngoscopy with the laryngeal mirror. This technique has become rare since the introduction of endoscopes. The mirror is warmed by hot air to prevent fogging.
Stimulation of the base of the tongue and posterior pharyngeal wall should be avoided, as it can provoke the gag reflex. The posterior surface of the mirror is used to lift the uvula and push it upward and backward. The posterior part of the tongue, the pharynx, and part of the larynx are now visible in the mirror. The patient is asked to say “ee” to bring the epiglottis into a more upright position and thus provide a better view of the larynx. In a patient with a sensitive gag reflex, it may be necessary to spray the pharynx first with a topical anesthetic such as lidocaine before the examination can be performed ( ▶ Fig. 4.6).
Fig. 4.6 Instruments for administering mucosal anesthesia in the larynx and for small interventions at the vocal folds. 1, Curved metal cotton applicator; 2, curved double-cupped forceps with handle; 3, curved needle holder for intralaryngeal injections; 4, spray, which can also be used with compressed air.
4.2.3.2 Flexible Nasendoscopy
A commonly used method for diagnostic assessment of the larynx is flexible nasendoscopy with a nasopharyngoscope (nasopharyngoscopy). The endoscope is introduced through the nose in the awake patient, either with or without topical nasal anesthesia. During endoscopy, the nasopharynx, the movement of the velum, and the motor function of the vocal folds can be observed. The flexible endoscope enables visualization of the hypopharynx, laryngeal closure during swallowing, and assessment of vocal fold movement. Endoscopes with charge-coupled device (CCD) chips at the tip provide sharp images and are useful for examining the vocal folds for organic diseases and phonatory movement using stroboscopy.
4.2.3.3 Rigid Endoscopy of the Larynx
Rigid endoscopes have become very useful in everyday practice. They are light, have wide-angle lenses, and can supplement or replace indirect laryngoscopy with the mirror. Two types with angles of 70 or 90 degrees are commonly used (see also section on nasal endoscopy, ▶ p. 149 and ▶ 151, and ▶ Fig. 2.21).
The advantages of this procedure are that it provides a good view of otherwise hidden areas, variable magnification, good illumination, sharp images, and video documentation. Surgical procedures can be performed using rigid videolaryngostroboscopy ( ▶ Fig. 4.7).
Fig. 4.7 Small lesions in the epithelium and lamina propria can be removed using topical anesthesia. The larynx is observed with a rigid endoscope held in one hand, and the lesion is grasped using the instrument held in the other hand. The patient holds the tongue. The procedure is monitored on a video screen.
Note: Biopsies can be taken and polyps removed during indirect laryngoscopy using topical anesthesia administered with cotton swabs or a spray (see also ▶ Fig. 4.6). Although most laryngologists prefer microlaryngoscopy, procedures using local anesthesia are still performed for phonosurgery, for taking biopsies, and to remove foreign bodies.
4.2.3.4 Microlaryngoscopy
The larynx and hypopharynx can be examined directly with a rigid laryngoscope resting via a lever arm on a chest support ( ▶ Fig. 4.8a, b). A binocular operating microscope is added for microlaryngoscopy. A micromanipulator is attached for laser surgery ( ▶ Fig. 4.8c), and suitable instruments have been designed for this ( ▶ Fig. 4.9). Anesthesia is administered intravenously and respiration is secured by endotracheal intubation or jet ventilation: A 5-mm catheter is inserted into the trachea through which air is blown into the lungs at a frequency of around 150 pulses per minute and flows back passively. Jet ventilation with total intravenous anesthesia has led to a considerable advance in diagnostic and endolaryngeal microsurgery that avoids the need for intubation. This technique facilitates both laser microsurgery and balloon dilatation, particularly in patients with narrow compromised airways. Excellent magnified images of the pharynx, larynx, and trachea can be viewed with either a microscope or a rigid endoscope. Delicate performance of endolaryngeal surgical procedures has led to the development of phonosurgery.
Fig. 4.8 (a) The first step in microlaryngoscopy. Introduction of the laryngoscope. The patient is in a supine position, with the upper teeth protected by a tooth guard. (b) The suspension arm is used to hold the laryngoscope in position. (c) Microlaryngoscopy with an attached laser micromanipulator. The laser beam is directed into the axis of the surgeon’s view. The endotracheal tube has to be a specialized laser tube.
Fig. 4.9 Instruments for endolaryngeal microsurgery. From top left: cutting forceps, forceps with fenestrated jaws, scissors, alligator forceps. Right: hand piece.
The following features are looked for during the examination: the color of the mucosa, abnormal tissue, the appearance of local or diffuse lesions (smooth, rough, ulcerated, exophytic, etc.), the lumen of the trachea, and the shape of the hypopharynx. It is not possible to observe the respiratory movement of the vocal folds under standard general anesthesia, but with light total intravenous anesthesia and jet ventilation, vocal cord movement with respiration may be assessed.
4.2.4 Diagnostic Imaging
High-resolution computed tomography (CT) allows accurate assessment of the site and extent of stenoses and tumors, and of any damage to local, laryngeal, and neighboring structures.
Magnetic resonance imaging (MRI) has greatly enhanced diagnostic imaging of the larynx, neck, and adjacent structures. Soft tissue findings such as the extent of a tumor and any lymph-node metastases can be displayed.
4.2.5 Stroboscopy
See section on Stroboscopy in Chapter 5.1.2 Voice Diagnosis and ▶ Fig. 5.1.
4.2.6 Other Special Techniques
4.2.6.1 High-Speed Video
A rigid endoscope is connected to a high-speed camera that can record 2,000 to 4,000 frames per second. Observations for short periods during the onset of phonation and during steady-state phonation can then be stored on a computer. This allows scientific analysis of laryngeal function and of the movement of the vocal folds during sound production in particular.
4.2.6.2 Electromyography
Electromyography (EMG) is the electrical recording of muscle activity. It aids in the diagnosis of diseases affecting muscle and peripheral nerves. EMG results can help determine whether symptoms are due to muscle disease or a neurological disorder. In the larynx, EMG is used to examine immobile vocal folds and differentiate between ankylosis or paralysis, for example.
4.2.6.3 Electroglottography
Electroglottography (EGG) measures the vocal fold vibration. A high-frequency (0.3–5 MHz), low current (<20 mA; 0.5 V) is passed through the neck via electrodes located outside on the neck on both sides of the thyroid cartilage. The current is greater when the vocal folds touch than when they are open. During vocal fold vibration, the impedance of the neck changes as the vocal folds have either more or less contact during phonation. These changes in impedance can be shown as an electroglottogram that can determine whether the vocal folds are closed and how fast they are closing. The EGG can also reliably determine the regularity vs. irregularity of vocal fold vibration.
4.3 Clinical Aspects
4.3.1 Congenital Anomalies
Congenital laryngeal anomalies have three cardinal clinical symptoms: dyspnea, dysphonia, and dysphagia ( ▶ Table 4.5 ).
Frequency | Congenital anomaly |
≈75% | Laryngomalacia |
≈10% | Neurological disorders (unilateral or bilateral recurrent nerve paralysis) |
Rare | Atresia and webs |
Cysts and laryngoceles | |
Subglottic stenoses | |
Hemangioma | |
Very rare | Clefts |
4.3.1.1 Laryngomalacia
Clinical features: Inspiratory stridor begins immediately or during the first few weeks postpartum, in severe cases accompanied by cyanosis. The symptoms worsen during feeding.
Pathogenesis: Abnormal calcium metabolism causes weakness in the supraglottic laryngeal skeleton, particularly in the epiglottis.
Diagnosis: Direct laryngoscopy and bronchoscopy. The epiglottis is usually omega-shaped and soft, and covers the laryngeal entrance on inspiration. The arytenoid prominences or aryepiglottic folds may be sucked in during inspiration. The shape and function of the vocal folds is normal.
Treatment: The neonate is observed carefully and the parents are given reassurance. The cartilage becomes stiffer during the course of weeks or months, and the symptoms gradually disappear. Feeding should be interrupted with pauses after every two or three swallows. In cases of respiratory distress, tube feeding is indicated. Severe temporary dyspnea should be managed in a neonatology intensive-care unit (NICU) with continuous positive airway pressure (CPAP) or intubation. Tracheotomy is only required exceptionally.
4.3.1.2 Neurogenic Disorders
Clinical features: If the symptoms are unilateral, there is squealing and a weak cry. Bilateral lesions cause inspiratory stridor.
Pathogenesis: Some cases are idiopathic, while some are due to congenital or cardiovascular anomalies or stretching of the neck during birth.
Diagnosis: Fiberoptic laryngopharyngoscopy or direct laryngoscopy, showing one or both vocal folds in the paramedian position. An intermediate position of the folds is considerably rarer.
Treatment: Unilateral lesions do not require treatment. A large proportion of congenital recurrent paralyses recover spontaneously. Bilateral lesions may require intubation initially, and tracheotomy later if obstruction persists.
4.3.1.3 Atresias and Webs
Clinical features: Atresias cause powerful, fruitless attempts at respiration, cyanosis, and inability to cry immediately after birth, leading rapidly to death. Webs cause respiratory obstruction of variable degrees.
Diagnosis: Direct laryngoscopy reveals atresia or a (subtotal) web at the glottis. The posterior edge of the web is often thin but the anterior section much thicker.
Treatment: In severe cases of dyspnea, asphyxia can only be prevented by endoscopic division of the web or tracheotomy in the immediate postpartum period. This can be done by incision or endolaryngeal laser surgery and may be repeated if necessary. Severe webs may require laryngotracheal reconstruction with anterior cartilage grafting.
4.3.1.4 Laryngoceles
Internal laryngoceles lie within the larynx in the vestibular fold ( ▶ Fig. 4.10).
Fig. 4.10 An internal laryngocele protruding into the right vocal fold.
External laryngoceles are a prolongation of the ventricle through the thyrohyoid membrane to form a palpable cystic mass in the neck.
Combinations of the two forms and bilateral laryngoceles are rare.
Clinical features: Dyspnea and dysphonia are accompanied by a foreign-body sensation in the throat.
Pathogenesis: This is a congenital or acquired expansion of the laryngeal saccule; a blind sac of the laryngeal ventricle (Morgagni ventricle), filled with air or mucus.
In adults, an occult cancer hidden in the laryngeal ventricle or saccule can cause a laryngocele and should always be actively excluded.
Diagnosis: This is established by laryngoscopy, palpation, and CT. The smooth swelling increases in size on puffing, straining, and on playing wind instruments.
Treatment: If patients have no dyspnea, observation is sufficient as long as the swelling does not increase. External laryngoceles are exposed and removed via an external incision. Small internal laryngoceles are removed using a CO2 laser during microlaryngoscopy.
4.3.1.5 Subglottic Stenoses
Clinical features: Inspiratory and expiratory stridor are present. The voice is usually normal. Recurrent pseudocroup may also occur.
Pathogenesis: Congenital subglottic stenosis is due to an anomaly of the cricoid cartilage. However, these infants are often intubated and it is therefore difficult to determine a congenital from an acquired subglottic stenosis.
Diagnosis: This is established by direct laryngoscopy, tracheoscopy, and CT.
Treatment: Tracheotomy may be necessary in severe respiratory obstruction. The child is then observed until surgery is possible at the age of 5 years. The procedures used are laryngotracheoplasty, anterior cricoid split, posterior cricoid split, and interposition of costal cartilage.
4.3.1.6 Hemangioma
Clinical features: These tumors typically occur in the subglottis in infants and present with progressively worsening stridor. Spontaneous bleeding with blood aspiration can lead to a dangerous emergency. There may be an associated cutaneous hemangioma.
Diagnosis: Direct microlaryngoscopy and bronchoscopy (MLB).
Treatment: While spontaneous resolution does occur, a subglottic hemangioma in an infant is life-threatening and tracheostomy may be necessary. Spontaneous regression of the hemangioma may occur over 1 to 5 years. Occasionally, when respiratory obstruction increases or the hemangioma bleeds spontaneously, laser surgery (with Nd:YAG or CO2 laser) is indicated.
4.3.2 Organic Functional Disorders
These can have neurological, myogenic, or articular causes. They are characterized by voice disorders such as dysphonia and aphonia, or by dyspnea, (e.g., laryngospasm).
Dysphonia: Atypical vibrations of the vocal folds or abnormally increased or decreased passage of air through the glottis causes increased hoarseness rather than a clear tone. It is analyzed using endoscopy, stroboscopy, high-speed cinematography, and phoniatry.
Dyspnea: Audible stridor (shortness of breath, at times accompanied by cyanosis) occurs when the diameter of the respiratory tract is reduced by at least one-third. The anoxia can increase dramatically during physical exercise.
Note: A 1-mm mucosal swelling in an infant narrows the lumen by more than 50%. Edema must be 3 mm thick in the adult to produce the same effect.
Neurogenic functional disorders due to causes in the cortical or subcortical areas mainly cause bilateral abnormalities of vocal fold movement. Bilateral, but more often unilateral, disorders of vocal fold function—usually combined with lesions of the vagus, glossopharyngeal, and hypoglossal nerves—are localized in the medulla oblongata. Cerebral ischemia or bleeding in the area of the brain stem leads to sudden combined paralyses of the superior and inferior laryngeal nerves in older people. Ninety percent of isolated defects of the vagus nerve or its branches are located in the region of the nucleus ambiguus, the inferior ganglion, and down to the peripheral laryngeal musculature. Typical vocal fold palsies result from damage to the vagus nerve inferior to the inferior ganglion ( ▶ Fig. 4.11).
Fig. 4.11 The vagus nerve and its branches, with sites of possible lesions (I–IV) and effects on the larynx. There is no rule for the position of the paralyzed vocal fold, only a trend. I, A lesion in the nucleus ambiguus (hemorrhage, neoplasm) produces paralysis in the intermediate or paramedian position. II, Loss of continuity in the jugular foramen (skull base tumors, aneurysms of the internal carotid artery) of the inferior ganglion causes paralysis of the superior laryngeal nerve and recurrent laryngeal nerve. The vocal fold is in the intermediate position, and the soft palate is paralyzed. Lesions in and around the jugular foramen may be accompanied by paralysis of the glossopharyngeal, accessory, and hypoglossal nerves. III, Interruption of the vagus nerve at the superior laryngeal nerve (carotid surgery) causes a loss of tone of the cricothyroid muscle and loss of tension in the vocal fold. IV, Division of the recurrent nerve (bronchial carcinoma, aortic aneurysm, thyroid surgery) causes vocal fold paralysis in the paramedian position.
The vocal folds are observed in different positions during function, or when paralyzed in relation to an imaginary reference line provided by the sagittal glottic axis ( ▶ Fig. 4.12).
Fig. 4.12 Positions of the vocal fold. 1, Median, or phonatory position; 2, paramedian position; 3, intermediate position; 4, lateral or respiratory position.
Physiological positions during function: During phonation, the vocal folds are in the median position ( ▶ Fig. 4.13a) (in adduction), and during inspiration ( ▶ Fig. 4.13b) they are in the lateral position (in abduction).
Fig. 4.13 (a) Normal larynx during phonation. (b) Normal appearance of the larynx during respiration.
Vocal Fold Positions in the Most Common Pareses: Classical teaching of neural disorders of the larynx described paralyzed vocal folds as being in the paramedian, intermediate or cadaveric position. These positions do not indicate the location of the neural lesion. They are mere descriptions that help to estimate the glottal gap during phonation.
The recurrent laryngeal nerve consists of adductor and abductor neurons, and reinnervation typically leads to dysfunctional laryngeal movement by innervation of the abductor and the adductor muscles at the same time. This condition is called synkinesis, where the vocal fold may be paretic rather than completely paralyzed, and its muscles do not atrophy.
Vocal fold bowing: The glottal chink is elliptical during phonation, due to reduced tension in the vocalis muscle as a result of atrophy, as occurs in senile dysphonia.
Transversus (interarytenoid muscle) weakness: A triangular gap remains open between the arytenoid cartilages and the posterior part of the vocal folds during phonation.
Combinations of the two forms of inadequate closure may occur.
It is not possible to predict the final position of the vocal folds after damage to the superior and recurrent laryngeal nerves, as the nerves may recover or partially preserve function ( ▶ Fig. 4.14). Vice versa, the extent of neural injury cannot be deduced from the position of the paralyzed vocal fold. In addition, atypical positions may be adopted due to fibrosis of the muscle or ankylosis of the arytenoid joint.
Fig. 4.14 Innervation of the larynx. 1, Vagus nerve; 2, superior laryngeal nerve (SLN); 3, internal branch of the SLN; 3a, superior branch of the internal SLN; 3b, middle branch of the internal SLN; 3c, inferior branch of the internal SLN; 4, external branch of the superior laryngeal nerve; 5, ventricular branch of the external SLN; 6, posterior branch of the recurrent laryngeal nerve; 7, anterior branch of the recurrent laryngeal nerve; 8, branches to the posterior cricoarytenoid muscle; 9, ansa galeni to the inferior branch of the internal SLN and branches to the interarytenoid muscle; 10, recurrent laryngeal nerve.
4.3.2.1 Recurrent Laryngeal Nerve Paralysis ( ▶ Table 4.6 )
All internal laryngeal muscles are paralyzed on the affected side. If the external cricothyroid muscle, supplied by the external branch of the superior laryngeal nerve, is still active, it stretches the paralyzed vocal fold and forces it into the paramedian position when phonating at a higher pitch. Stroboscopy is useful in the long-term follow-up of vocal fold paralyses. If the mucosal wave can be observed in the course of paresis, it is a sign that neural function is recovering; the vocalis muscle builds up tension suggesting a positive prognosis.
Causes | Details |
Intracranial portion of the vagus nerve, including nuclei | |
Neurological diseases | Wallenberg syndrome (posterior inferior cerebellar artery syndrome). Occlusion of the vertebral or posterior inferior cerebellar artery of the brain stem, in which the lateral part of the medulla oblongata infarcts. Symptoms include difficulties with swallowing, hoarseness, dizziness, nausea and vomiting, rapid involuntary movements of the eyes (nystagmus), and problems with balance and gait coordination |
Poliomyelitis, bulbar paralysis, multiple sclerosis, cerebral tumors | |
Cervical portion of the vagus nerve | |
Thyroidectomy | Most frequent cause of vocal fold immobility |
Malignant goiter | |
Blunt or sharp cervical trauma | |
Cervical metastases near the skull base | Commonly associated with other cranial neuropathies |
Intubation anesthesia | Stretching of the recurrent nerve due to incorrect patient positioning; pressure of the tube against the anterior branch inside the larynx; pressing of the larynx against the vertebral column |
Thoracic portion (mediastinum) of the vagus nerve | |
Operations on the hypopharynx or esophagus | Failure to display the course of the nerve during resection of the hypopharyngeal diverticulum |
Esophageal carcinoma | Particularly of the upper third |
Mediastinal diseases | Lymphogranulomas, non-Hodgkin lymphoma, metastases, mediastinitis |
Aneurysms of the aorta or subclavian artery | Congenital or acquired |
Duct operations | |
Cardiomegaly of various causes | May also occur in Ortner syndrome (a rare cardiovocal syndrome in which there is recurrent laryngeal nerve palsy secondary to cardiovascular disease) |
Bronchial carcinoma | Particularly common in tumors arising from the left upper and middle lobes and with involvement of the mediastinal lymph-node metastases |
Pulmonary tuberculosis | |
Pleural plaques | |
No specific location | |
Infectious and toxic | Influenza; herpes zoster; rheumatism; syphilis; tissue toxins such as lead, arsenic, or organic solvents; streptomycin; quinine |
Idiopathic | It should be noted that a diagnosis of idiopathic recurrent nerve paralysis should only be made after all other causes have been excluded. In the great majority of these patients, spontaneous recovery occurs within 2–3 months. After a longer period, the chances of recovery are lower |
4.3.2.2 Unilateral Recurrent Nerve Paralysis
Clinical features: Often noted incidentally, the symptoms include moderate-to-severe dysphonia in the acute phase. The voice improves later. There is no appreciable respiratory obstruction except during severe physical activity. The patient cannot sing high notes or raise his voice. A history of dysphagia or aspiration should be sought. A sense of being short of breath, the so-called phonatory dyspnea, may occur due to glottic air-escape when vocalizing.
Diagnosis: Laryngoscopy shows an immobile vocal fold in variable positions. The arytenoid on the paralyzed side is often prolapsed forwards. Thorough laryngologic, phoniatric, neurologic, and radiologic examinations are indicated to identify the cause (see ▶ Table 4.6 ).
Treatment: If treatment of the causal disease does not restore vocal fold mobility, the patient is given voice therapy to achieve glottal closure by activating the remaining neuromuscular units on the paralytic side and stimulating the mobile vocal fold on the other side.
Consideration should be given to injection laryngoplasty early after onset of the paresis due to a laterally positioned vocal fold, or if dysphagia or aspiration become problematic. Injection techniques include the application via direct laryngoscopy or transcutaneous and per-oral with local anesthesia. There are several injection materials, including autologous fat, hyaluronic acid, and calcium hydroxylapatite.
If the paralysis is thought to be permanent, consideration should be given to laryngeal framework surgery. The lateralized cord can be repositioned toward the midline by medialization thyroplasty, in which a biologically inert implant or autologous cartilage is inserted into the paraglottic space via a window in the thyroid cartilage. Arytenoid adduction may also be performed in specialist units.
Nonselective reinnervation surgery by anastomosing the ansa cervicalis with the recurrent nerve stump has had some promising results, but is highly specialized and very time-consuming.
4.3.2.3 Bilateral Recurrent Nerve Paralysis
Symptoms: Dyspnea and danger of asphyxia due to narrowing of the glottal chink. Inspiratory stridor occurs during physical activity, sleep, or when talking.
Initially, the voice may be aphonic for a variable period—between 4 and 8 weeks, depending on the cause—and become breathy or rough after that. Speech is interrupted by long inspiratory phases.
Feeble coughing is also symptomatic.
Pathogenesis: See ▶ Table 4.6 .
Diagnosis: This is based on laryngoscopy. In bilateral paralysis, the vocal folds are usually in the paramedian position.
Treatment: Relief of the airway takes first priority. Tracheotomy and a cannula with a speaking valve are required only if dyspnea is severe, i.e., if peak expiratory flow goes below 40% of the normal value for the patient. Many patients manage to stay without tracheotomy by avoiding exertion, as the dyspnea is tolerable as long as they are at rest.
If spontaneous remission does not occur, surgery to widen the glottis is indicated 10 to 12 months after the onset of the paresis if the patient is suffering from permanent dyspnea and physical activity limitation or, in case of tracheostomy, if the patient wishes to be free of the speaking valve. The recommended procedure is partial arytenoidectomy and posterior cordectomy.
Principles of surgery: The operation is carried out endoscopically with a CO2 laser ( ▶ Fig. 4.15a–e). The part of the vocal process of the less mobile arytenoid cartilage that is obstructing the lumen of the cricoid ring below is removed (partial arytenoidectomy), and the elastic cone is opened all the way down to the cricoid. The posterior part of the vocal fold is incised and part of the vocalis muscle is removed (posterior cordectomy). The inferior part of the subglottic mucosa is sutured laterally to the floor of the Morgagni ventricle and ventricular fold.
Fig. 4.15 The principle of partial arytenoidectomy and posterior cordectomy with intralaryngeal sutures. (a, b) The intraluminal part of the vocal process of the arytenoid cartilage is resected with laser surgery, and the incision through the conus elasticus is extended laterally to the cricoid cartilage. (c) The posterior part of the vocal fold is opened with a triangular incision, and the underlying vocalis muscle is resected. (d, e) The inferiorly based flap from the posterior part of the vocal fold is sutured laterally to the ventricular fold. This creates optimal conditions for wound healing (e), with minimal fibrin and granulation tissue formation. If the anterior part of the vocal fold can still be adducted, it can be used for phonation.
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