This benign tumor was first described by Virchow in 1863. He defined it as an anomalous air sac communicating with the laryngeal ventricle. He initially used the term "laryngocele ventricularis" to describe this condition.
Laryngoceles are intimately associated with laryngeal saccule, which is infact an appendix of the laryngeal ventricle. This is a membranous sac located between the false cord and the inner surface of the thyroid cartilage.
Laryngoceles could possibly result from abnormally large saccule that extend above the level of thyroid cartilage. These structures communicate with the laryngeal lumen and is filled with air. These laryngoceles could be congenital and acquired.
Developmentally the saccule develops as an outpouching 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 pseudostratified ciliated columnar epithelium. It also contains numerous mucous glands in the submucosal areolar tissue. These glandular secretions keep the vocal cord moist and lubricated hence saccule is known as the oil can of the larynx.
The laryngoceles must be differentiated from saccular cyts; which is filled with mucous, and donot communicate with the laryngeal lumen. These saccular cysts are common in infants while laryngoceles are common in adults.
Differences between laryngocele and saccular cysts
|Filled with air||Filled with mucous|
|Common in adults||common in children|
|Sac communicates with laryngeal cavity||
Sac does not communicate with
Types of laryngoceles:
Three types of laryngoceles have been described. They are 1. Internal laryngocele, 2. External laryngocele, and 3. Combined laryngocele.
Internal laryngocele: is confined to the interior of the laryngeal cavity. It extends into the paraglottic region of the false vocal cord and aryepiglottic fold.
This type of laryngocele extends and dissects superiorly through the thyrohyoid membrane. It is intimately associated with superior laryngeal nerve. It is called external laryngocele because it frequently presents itself as lateral neck mass.
In this type both internal and external components of laryngcele exist together.
Diagram showing internal laryngocele
Image showing combined laryngocele
If the communication between the laryngocele and the laryngeal lumen gets occluded, fluid may get accumulated within the sac. If the accumulated fluid is mucoid in nature the term laryngomucocele is used. If it is filled with pus then laryngopyocele is used to describe the mass.
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 play a role in the pathophysiology of development of laryngocele. Infact 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.
Mostly laryngoceles are incidentally discovered during routine laryngeal examination. Symptoms if present may include:
1. Hoarseness of voice
3. Foreign body sensation in the throat
4. External / Combined laryngoceles may present with a neck mass close to the thyrohyoid membrane.
5. Large internal laryngoceles / combined laryngoceles may cause airway obstruction.
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 submucosal mass in the region of false vocal cord. If fibre 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.
Radiological examination: Plain xray soft tissue neck show air filled sac protruding from the soft tissues of neck. When xray is repeated on valsalva maneuver the size of the mass shows increase in size. Small internal laryngoceles are difficult to identify radiologically in plain films. CT scans are diagnostic.
External lateral neck approach is commonly favored by most surgeons to excise laryngocele because of its excellent exposure, minimal morbitidity and reduced chances of recurrence. To manage internal laryngoceles a small portion of thyroid cartilage may have to be removed to allow adequate exposure. External and combined laryngoceles can be dissected via the thyrohyoid membrane and cartilage sacrifice is not required.
The surgeon approaches the mass through a horizontal incision over natural skin crease just over the region of thyrohyoid membrane. The mass overlies this area hence there may not be any difficulty in identifying the thryohyoid membrane area. Skin flaps are elevated in the subplatysmal plane. The bulging strap muscles may be transected for better exposure of the mass. The carotid sheath is pushed posteriorly. The ansa cervicalis nerve may be adherent to the laryngocele and may be dissected out / transected if necessary. When the laryngocele is delivered there is dehiscence in the thryohyoid membrane which is closed with sutures.
During this procedure the superior laryngeal nerve must be identified and carefully preserved since it could be intimately related to the mass.
Complications of this procedure include:
1. Airway compromise due to mucosal oedema
2. laryngo cutaneous fistula
3. Subcutaneous emphysema
4. Injury to superior / internal laryngeal nerve
Laryngofissure: Here larynx is opened in the midline. A submucosal or transmucosal technique can be used to remove small internal laryngoceles. The major disadvantage of this procedure is the risk of anterior commissure blunting and subglottic stenosis.
Endoscopic approach: can be resorted to in small internal laryngoceles. The cyst is decompressed internally. Recurrence is common in this procedure.