Laryngocele is an abnormal dilatation or herniation of the laryngeal saccule that extends upward within the false vocal fold in communication with the laryngeal lumen. It is a rare benign lesion of the larynx and has been classified as either internal or combined. The formerly used classifications of internal, external, and combined laryngoceles are being abandoned because a purely external laryngocele cannot exist since laryngoceles originate at the laryngeal saccule. An internal laryngocele is medial to the thyrohyoid membrane, while a combined laryngocele lies both medial and lateral to the thyrohyoid membrane.
Laryngoceles are categorized as internal or combined. The formerly used classification into internal, external, and combined laryngoceles is being abandoned because purely external laryngoceles cannot exist, as laryngoceles originate at the laryngeal saccule. An internal laryngocele is confined within the false vocal fold, medial to the thyrohyoid membrane. A combined laryngocele extends upward and protrudes through the thyrohyoid membrane to the neck. If the neck of the laryngocele becomes obstructed (causes of which include tumours and chronic inflammation of the larynx), the mucus produced by the mucous glands of the lining epithelium can accumulate, leading to a laryngomucocele. When it is infected, a laryngopyocele forms.
Laryngoceles are rare lateral neck masses. They are more commonly found in men than women in a 5 to 7:1 ratio and in the fifth or sixth decade of life. Eighty to eighty-five percent of laryngoceles have been found to be unilateral with no predominance of occurrence on the left or right side. The most common type of laryngocele is the combined type.
The simple laryngocele is filled with air. When the neck of the laryngocele is obstructed, it becomes filled with mucus of glandular secretion and is altered to a laryngomucocele. When this lesion becomes infected, a laryngopyocele is formed.
This condition was first described by Virchow in 1867. It was Virchow who coined the term Laryngocele. The first clinical description of Laryngocele was by Larry Surgeon of army in Egypt in 1829. He described it as a compressible pouch related to thyrohyoid membrane. Majority of laryngoceles are asymptomatic and can be managed conservatively. Surgery is reserved only for symptomatic cases.
Developmentally the saccule develops as an out pouching of the laryngeal cavity during the second month of intrauterine life. It is relatively large at birth, but continues to regress in size. The saccule is lined by pseudo stratified ciliated columnar epithelium. It also contains numerous mucous glands in the sub mucosal areolar tissue. These glandular secretions keep the vocal cord moist and lubricated hence saccule is known as the oil can of the larynx.
Factors that cause an increase in intra laryngeal pressure like coughing, straining, blowing wind instruments may cause laryngocele. Gradual weakening of the laryngeal tissues due to aging also plays a role in the Pathophysiology of development of laryngocele. In fact laryngoceles have been considered to be a health hazard in glass blowers. The neck of the saccule has been postulated to act as a one way valve allowing accumulation of air and preventing its egress.
Etiology of laryngocele is not very clear. Lots of controversies shroud this topic. Laryngoceles have been described in neonates; hence congenital element could also be involved. Anatomical variations of saccule combined 6 with raised intra laryngeal pressure could play a role.
Laryngoceles are rare in infants. If they are found they are invariably congenital in nature. They must be carefully differentiated from saccular cysts. These congenital laryngoceles may be managed conservatively, provided there is no airway compromise. If saccular cysts are present in infants they must be decompressed / aspirated.
Since laryngoceles may be associated with laryngeal malignancies, its presence in a old patient should prompt the examiner to diligently search for laryngeal malignancy.
Indirect laryngoscopy is diagnostic. Indirect / combined laryngoceles appear as sub mucosal mass in the region of false vocal cord. If fiber optic laryngoscope is used these masses can be seen to enlarge during a valsalva maneuver. In pure external laryngoceles endolaryngeal examination will be normal.
If combined laryngocele is presenting as a neck mass, compression will cause a hissing sound as the air escapes from it (Bryce sign) into the larynx. This test is fraught with danger in cases of combined laryngoceles because air from the external component may get forced into the internal component causing acute airway obstruction.
Symptoms of laryngocele are dependent on their type. External and combined laryngoceles present with neck mass anterior to the sternomastoid muscle. Classically this mass is soft in nature, reducible and increases in size on Valsalva maneuver. Laryngoceles are usually non tender and soft. If the neck mass is tender, and tense then infected laryngocele / pyocele is a distinct possibility.
The laryngoceles must be differentiated from saccular cysts; which is filled with mucous, and don't communicate with the laryngeal lumen. These saccular cysts are common in infants while laryngoceles are common in adults.
Laryngocele is a rare condition. It is commonly an incidental finding. Management is dependent on the type of laryngocele. Small internal laryngoceles can be managed by endoscopic resection while large external and combined laryngoceles can be removed via external approach. Use of laser has facilitated safe endoscopic resection of internal laryngoceles.