The skeleton of the larynx comprises the hyoid bone, the thyroid cartilage and the cricoid cartilage. The cricoid cartilage is the only complete cartilaginous ring in the airway. The arytenoid cartilages sit on the cricoid cartilage and the movement of the arytenoids drives the tension and mobility of the vocal cords.
	The functions of the larynx include respiration, phonation, protection of the lower airway and closure of the laryngeal sphincter as part of the Valsalva maneuver and for heavy lifting.
	Hoarseness (trachyphonia) is a very common symptom of laryngeal disease. Hoarseness may be the result of inflammation, benign or malignant tumor or vocal cord paralysis.
	Stridor is an audible sound that is produced during respiration as the air column moves through a narrow site in the airway. The timing of the stridor suggests the location of the narrowing or obstruction. Inspiratory stridor suggests an obstructive site above the level of the true vocal cords. Expiratory stridor suggests a narrowing in the trachea or bronchi. Biphasic stridor (heard during inspiration and expiration) suggests an obstruction at the level of the true vocal cords.
	The patient’s history will suggest the type of problem causing hoarseness. First, the duration of symptoms is important as hoarseness of a few days duration suggests an infectious or inflammatory etiology, hoarseness of several months duration suggests a benign or malignant neoplasm, and hoarseness present since birth suggests a congenital lesion. The age of the patient is important in that hoarseness and stridor in an infant will almost certainly be due to a congenital lesion while hoarseness in a patient past 40 strongly suggests the possibility of a malignant neoplasm. Associated events such as yelling at a ball game or suffering a recent URI will suggest an inflammatory problem while hoarseness associated with indigestion raises the possibility of reflux laryngitis. Personal habits such as smoking and heavy intake of alcohol again suggests a possible malignant tumor.
	Evaluation of the larynx is performed by palpation of the laryngeal skeleton, indirect mirror examination of the larynx, flexible laryngoscopy or evaluation through a rigid laryngoscope. Only endoscopy can establish a true diagnosis for stridor. After flexible nasopharyngoscopy (best evaluation of vocal cord motion) has been performed, if able to be performed on a non-urgent stridor, attention then turns to rigid endoscopy. Endoscopy begins with complete visualization of the supraglottis, glottis, subglottis, measurement of the air passage, and examination of mucosal contour. At the end of the procedure, when the anesthesia level lightens, vocal cord mobility may be assessed.

2. Pediatric Laryngeal Disease

	Supraglottitis (epiglottitis) is a life threatening condition seen usually in children and characterized by the abrupt onset of fever, drooling, cyanosis, airway obstruction and dysphagia. Supraglottitis is bacterial in origin with H.Flu B being the predominant organism. Children are usually affected between the ages of 2 to 6. It usually develops suddenly with high fever, drooling, sitting forward, and odynophagia. The infant is usually rapidly rushed to the operating room where intubation is performed in a controlled setting with exam of the epiglottis revealing a cherry red, swollen epiglottis. Cultures are obtained from the epiglottis and the patient is left nasally intubated for 2 to 3 days until the swelling subsides and the patient has an air leak. The important point to remember is that if the patient is hypoxic you must get them to the operating room as rapidly as possible to stabilize the airway. Antibiotic therapy with cefuroxine or ceftriaxone is recommended along with humidification.
	Acute croup is the most common cause of acute stridor in children caused by the parainfluenza virus typically occurs in fall and spring. It is generally benign condition that is manifested in a young infant usually with a low grade fever, barking cough, and occasionally biphasic stridor occurring over a period of days. A steeple sign may be visible on AP views of the subglottic airway. Stridor usually resolves over several days and few patients require hospitalization. Those that do are children with tachypnea (greater than 40/min.), retractions, and cyanosis. Hospitalization usually requires supplemental measures of cold humidification, oxygen, racemic epinephrine, and occasionally steroids. One dose of steroids does seem to be effective in resolution at a dose of 1 mg. per kg. Intubation is necessary only for severe respiratory distress and may be required for 4 to 5 days.
	Congenital anomalies include laryngomalacia (the most common), laryngeal web, laryngeal cyst and laryngocele. Laryngomalacia involves an immature and flaccid larynx and is the most common cause of infant stridor. It usually worsens shortly after birth, then improves spontaneously, but some infants with this problem will require a tracheotomy. The stridor is worsened by crying or in an excited state often in the supine position where the supraglottic structures may collapse inward. Pectus excavatum is occasionally seen but the relationship to laryngomalacia remains unclear possibly related to chronic sternal retractions. Debate continues to rage about the exact cause of laryngomalacia but the predominant theories seem to indicate that immature neuromuscular control of the cartilages contributes to the inward collapse instead of the other theories that abnormal cartilaginous laxity contributes to this condition. The neuromuscular theory is enhanced by the fact that coexistent GERD sometimes exists lending credence to this theory. If feeding difficulties, apnea, cyanosis or failure to thrive develop, surgical measures may be necessary to relieve the difficulties. Laryngeal webs occur at the level of the glottis and represent a failure of the embryological laryngotracheal membrane to resolve at about 10 weeks of embryologic life. The web may be minimal to completely obstructive. Laryngeal cysts represent a disturbance of fetal development and usually occur above the level of the true vocal cords. Subglottic hemangiomas are an uncommon cause of stridor in newborn infants. 50% of infants with subglottic hemangioma will have cutaneous hemangioma. Subglottic hemangioma is a soft, compressible mass that usually does not bleed spontaneously. Most of these will resolve during the first year of life, but if they are obstructive or persistent, they can be removed using a CO2 laser.
	Weakness and paralysis of the vocal cords is the second most common cause of neonatal stridor. Congenital malformations that impinge on the brainstem may cause bilateral vocal cord paralysis necessitating an airway emergency. Bilateral paralysis may cause a normal cry with severe respiratory stridor and distress. This is due to the traction on the vagus nerves (eg. From an intracranial bleed). Usual presentation of unilateral vocal cord paralysis is hoarseness that sometimes improves when the patient lies down on the side with the paralyzed vocal cord as gravity allows the vocal cord to settle. Unilateral paralysis usually has a weak cry but airway intervention is only occasionally necessary. The other cord tends to compensate with time. Most cases are idiopathic and flexible nasopharyngoscopy can routinely make the diagnosis.
	Subglottic stenosis occurs when the airway lumen at the level of the cricoid measures less than 3.5 mm. Most commonly, this condition is acquired secondary to intubation of premature infants however congenital subglottic stenosis can also exist. Symptoms may include recurrent "croup," biphasic stridor, retractions, normal cry but air hunger may lead to feeding difficulties. Endoscopy is required to make the diagnosis. It is important to distinguish congenital subglottic stenosis from acquired subglottic stenosis. Congenital stenosis results from incomplete canalization of the subglottis with a usual milder presentation. Most congenital stenoses improve as the child’s larynx grows and patients generally only become symptomatic with upper respiratory infections. Acquired subglottic stenosis is generally more severe than congenital subglottic stenosis.
	Foreign bodies may cause stridor in newborns and infants and a high degree of suspicion is always warranted. Immediate stridor accompanied by choking is strongly suggestive of a foreign body. Prompt urgent management is necessary in these cases and even esophageal foreign bodies may impinge on the trachea causing stridor or other adventitious sounds. Lower airway foreign bodies may induce airway trapping with atelectasis of the normal side and hyperinflation of the affected side.

3. Common Adult Laryngeal Disease

	Laryngeal inflammation may be caused by vocal abuse, viral or bacterial infections and allergies.
	Chronic laryngitis may take the form of chronic hyperplastic laryngitis, a contact ulcer, polypoid corditis, vocal cord polyp or vocal cord nodule.
	A contact ulcer is a benign lesion resulting from acute local trauma caused by coughing or intubation. The mucosa is ulcerated over the arytenoid cartilage and the patients usually respond to complete voice rest.
	Polypoid corditis is a benign condition representing chronic irritation and usually involving the entire vocal cord surface. Treatment consists of direct laryngoscopy and vocal cord stripping and cessation from smoking which is the usual cause.
	Vocal nodules are benign lesions that result from chronic irritation and usually present at the junction of the anterior and middle one-third of the vocal cord. During their early phase they are soft and compressible and respond to voice therapy. After many months or years they become fibrotic and treatment consists of excision and voice therapy.

4. Laryngeal Cancer

	Cancer of the larynx is increasing in incidence, particularly in women because of their increased smoking. Hoarseness may be the only symptom and it is essential that the physician be able to see the larynx to make the diagnosis. A T1 lesion (early lesion involving one vocal cord) has a 90% curability. A T3 lesion (fixed vocal cord) has only a 60% survival rate. Early diagnosis is the key to successful management by conservation surgery or radiation therapy.
	Glottic cancer usually causes hoarseness during its early stages. It is a lesion that can be visualized and should allow for early diagnosis.
	Cancer of the larynx may arise at sites other than on the true vocal cord and present with symptoms other than hoarseness. Patients may describe a lump in the throat (lesion of the false vocal cord, ventricle, epiglottis) or dysphagia (lesions in the vallecula or the piriform sinus). Patients may also present with a mass in the neck as the first sign of laryngeal cancer.
	Hoarseness lasting longer than two weeks is cancer until the physician proves otherwise in a patient past 40 years of age. The likelihood of cancer is even greater in older patients with a history of smoking and alcohol intake.
	Partial laryngectomy is a removal of a portion of the larynx with preservation of most of the larynx and good laryngeal function. These techniques are possible because embryologically the larynx arises as paired right and left halves and as embryologically separate superior and inferior halves. The hyoid bone is derived from the second and third branchial arches and the epiglottis from the fourth branchial arch. The cricoid cartilage is derived from the sixth branchial arch. The lymphatic drainage from the larynx is predictable and corresponds to these embryological origins.
	Advances in partial laryngectomy allow adequate cancer surgery with preservation of laryngeal function. But the greatest strides will be made in the future by stronger preventive measures and by earlier diagnosis of laryngeal cancer.

larynx.htm - Last Update: 98/11/30,12:00