Benjamin-Inglis classification of laryngotracheal clefts. Type 1 is a supraglottic interarytenoid cleft. Type 2 is a partial cricoid cleft. Type 3 extends to cervical trachea. Type 4 extends to thoracic trachea (From Benjamin and Inglis [1], with permission)
While several classifications have been proposed for laryngeal clefts, the Benjamin-Inglis system [1] is most commonly used (Fig. 27.1). This system divides clefts into four categories of ascending severity based on the distal extent of the cleft. Type 1 clefts are restricted to the interarytenoid space and do not enter the cricoid cartilage; they generally involve the interarytenoid muscle and overlying mucosa in isolation. Anatomically, these can be defined as “supracricoid, interarytenoid” clefts and extend to or just below the true vocal folds [2]. A related and more controversial condition is the so-called deep interarytenoid notch , also known as a “type 0” laryngeal cleft; this involves an interarytenoid notch that is judged to be deeper than average but that does not extend to the level of the glottis. Diagnosis of this condition is quite subjective. However, it appears that treatment of this condition may improve symptoms of dysphagia [3, 4], suggesting that even a “deep notch” may have functional significance.
Endoscopic view demonstrating a type 2 laryngeal cleft. The alligator forceps are distracting the left arytenoid cartilage to allow visualization of the cleft
Endoscopic view of an iatrogenic type 3 laryngeal cleft resulting from previous endoscopic posterior cricoid split. The metal probe is in the esophagus
Epidemiology and Associated Conditions
While experience suggests that laryngeal clefts are quite common, their actual incidence is not well-documented in the literature. One available estimate is 1 in 10,000 live births and 1.5% of all congenital laryngeal anomalies [5]. The proportion of syndromic laryngeal clefts is unknown. However, specific syndromes are associated with this anomaly. These include Opitz G/BBB (also known as Opitz-Frias), Pallister-Hall, VATER (vertebrae, anus, trachea, esophagus, renal)/VACTERL (vertebrae, anus, cardiac, tracheoesophageal fistula, renal, limb), and CHARGE (coloboma of the eye, heart defects, atresia of the choanae, retardation of growth and development, ear abnormalities) associations. All of these syndromes also include associations with other airway anomalies, particularly tracheoesophageal fistula [6]. Indeed, some authors suggest that every patient with tracheoesophageal fistula be evaluated for laryngeal cleft [7] regardless of whether the patient has a diagnosed syndrome, and we support this recommendation.
Pathophysiology
The embryogenesis of laryngeal clefts is unknown. In general, these lesions are thought to result from incomplete fusion of the posterior larynx.
Clinical Presentation
Laryngeal clefts vary greatly in clinical presentation, from asymptomatic lesions to those that cause life-threatening compromise of feeding and breathing in the immediate postnatal period. While each Benjamin-Inglis cleft type has not been clearly tied to specific symptoms, experience suggests that symptoms are typically worse in frequency and severity with increasingly distal cleft extent. Type 0 and type 1 clefts may be asymptomatic or may cause symptoms including coughing or choking with feeds, wet voice or wet cough during or after feeds, or recurrent respiratory infections. Our experience suggests that most children with these shallow clefts have normal swallow function unless another factor “tips them over” into aspiration. Examples of such factors include neurologic or neuromuscular disease and poor oral coordination during feeding. This experience is corroborated in the literature by examples of patients not presenting until they acquire other conditions during adulthood [8]. Some children may also have symptoms only when drinking thin liquids, drinking rapidly or with large boluses, or swallowing when they are distracted.
Differential Diagnosis
Work-up and management of laryngeal clefts depend most of all on the clinician’s having some index of suspicion that this condition is present. Because the symptoms of laryngeal cleft overlap with multiple other conditions, and because laryngeal cleft may be very difficult to diagnose on in-office flexible laryngoscopy, this condition must be kept consciously in the differential diagnosis of a patient with the symptoms described in the previous section. Other conditions that may be associated with similar clinical presentation are listed in Box 27.1.
Box 27.1: Differential Diagnosis for Laryngeal Cleft
Reduced pharyngeal or laryngeal sensation
Laryngomalacia
Unilateral or bilateral vocal fold weakness or immobility
Tracheoesophageal fistula or bronchoesophageal fistula
Subglottic stenosis
Nasal or upper airway obstruction (in infants)
Neurologic causes of dysphagia including Chiari malformation and cranial neuropathies
Any focal or systemic condition causing dysphagia
Any cause of recurrent lower respiratory infections, wheezing, or persistent cough, including reflux, persistent bacterial bronchitis, and asthma
Speech-Language Pathologist Approach
Speech-language pathologists (SLPs) have been involved in the evaluation and management of feeding and swallowing disorders in pediatric populations for more than five decades. The prevalence of feeding/swallowing disorders in infants and children has increased as medical and surgical advancements are made including increase in survival of premature births, many resulting in complex medical conditions [9]. It is estimated that in an otherwise healthy pediatric population, the incidence of feeding related disorders is 25–45%, and in those with developmental disabilities, the incidence may be up to 80% [9]. This increased incidence requires more specialized methods of evaluation that are able to assess the anatomy and physiology of the swallowing mechanism that cannot be captured with a clinical swallow evaluation [10]. This includes a small portion of patients that may have dysphagia related to a laryngeal cleft [9].
Clinical Swallow Evaluation
Obtaining a thorough clinical history from parents/caregivers regarding symptoms as well as an examination of the oral mechanism for any evidence of anatomical abnormality or cranial nerve involvement is imperative when evaluating a child for feeding/swallowing issues. If clinical history includes coughing or choking during feeds, difficulty feeding in general, failure to thrive, “wet” or noisy breathing or difficulty breathing during or after feeds, and recurrent pulmonary infections, a laryngeal cleft should be in the differential diagnosis [11, 12]. An oral mechanism examination includes close examination of the face and oropharynx, observation for evidence of respiratory distress, and voice assessment which includes observing for breathiness, hoarseness, etc. that may indicate vocal fold involvement [13].
Instrumental Swallow Evaluation
Videofluoroscopic Swallow Study (VFSS)
In cases where a laryngeal cleft is suspected or included in the differential diagnosis, a pattern of penetration/aspiration that occurs during the swallow may be observed. The patient may or may not be symptomatic to these episodes. The swallow pattern may be well coordinated initially; however, if penetration/aspiration is occurring, the swallow may become increasingly discoordinated as the study continues due to increased difficulty trying to coordinate breathing and swallowing. Typically, there would not be any post-swallow residue or pooling of material in the pharynx after the swallow unless there are other diagnostic considerations.
Overall, according to Johnston et al. [11], a study that shows aspiration in an otherwise healthy child strongly correlates with an anatomic abnormality. They state that 75% of patients who have a type 1 or type 2 laryngeal cleft will show aspiration on VFSS. However, it is important to note that in patients with intermittent symptoms, the study may appear normal without witnessed events of penetration/aspiration during the examination. Additionally, Miglani et al. [9] showed that patients who have penetration/aspiration and a laryngeal cleft also have a high rate of swallow dysfunction affecting all phases of the swallow. Finally, Johnston et al. [11] remind us that many patients may have multiple swallow studies done in the course of their work-up, and therefore, cumulative radiation exposure should be considered.
In addition to VFSS being helpful in identifying feeding difficulties and penetration/aspiration, it can also be a tool for monitoring patient progress during feeding therapy as well as after procedural interventions [9].
Fiberoptic Endoscopic Evaluation of Swallowing (FEES)
FEES findings in patients with laryngeal cleft are similar to those seen on VFSS. Many children will have a normal-appearing larynx on awake flexible endoscopy. In some cases, the cleft may become visible with abduction of the vocal folds during inspiration, though a high index of suspicion is needed, and the sensitivity and specificity of awake laryngoscopy for this diagnosis remain unknown. In deeper laryngeal clefts, redundancy of the mucosa lining the cleft may lead to visible prolapse of posterior laryngeal soft tissues into the glottis aperture with inspiration, with associated stridor. Some clinicians look for the “ram sign,” in which the shape of the redundant mucosa suggests the curling horns of a ram, though this finding is much more visible on rigid airway endoscopy under anesthesia.
During the swallow evaluation portion of FEES, some patients may demonstrate visible laryngeal penetration through the interarytenoid region. This finding is of course very suggestive of a laryngeal cleft. Most patients, however, will either not demonstrate penetration/aspiration or will have the typical “whiteout” during the pharyngeal swallow itself but have visible swallowed material within the larynx, suggesting entry of this material during the “whiteout.” Indirect clues to aspiration, such as wet cough, wet voice, or wet breathing, may suggest penetration or aspiration, but they are not specific to the diagnosis of laryngeal cleft. Signs of aspiration may be more evident with thinner textures, more rapid flow of material into the pharynx, or with mixed textures.
Management
Management of swallowing problems in patients with laryngeal cleft who demonstrate penetration or aspiration will vary depending on the severity of symptoms and need for multidisciplinary interventions.
Management options may include surgical intervention for correction of anatomical defect, feeding therapy and/or diet modifications, and medical management. For purposes of this section, feeding therapy and/or diet modifications will be the focus, although it is difficult to completely separate them from each other as it is more likely that a component of all of them will be involved.
Miglani et al. [9] describe conservative management including diet modifications, possibly to include thicker liquids in addition to medical management if laryngeal clefts are small and consequences are considered mild. The specifics of thickening vary between centers and clinicians, with some providers thickening feeds in very young infants and others avoiding this strategy until the patient is at least 1 year of age. More aggressive diet modifications or limitations in addition to medical management and surgical intervention may be required for more severe aspiration events with more significant medical sequelae. Depending on severity, oral intake may not be safe regardless of diet modifications, and other routes for nutrition may need to be considered.
Treatment goals for any child with laryngeal cleft and associated swallowing issues are to achieve the least restrictive diet that allows for continued safe and efficient oral intake. Age limitations may play a role in what consistencies are tested and what consistencies are recommended. Feeding therapy, outside of modifications to diet, may also be indicated to address behavioral feeding issues and skills (for both caregiver and child) that may reduce risk of aspiration while allowing for continued, efficient oral intake. This may include pacing and positioning strategies. Altering the flow of liquids via a slow flow nipple may also be an alternative for infants who aspirate thin liquids but are too young to thicken feeds.
In summary, the goal of any treatment plan should be to support adequate and safe nutrition; swallowing function can improve simply due to patient growth and maturation over time [11]. Diet advancement or changes in recommendations are determined by the patient’s progress as well as repeated instrumental and clinical swallowing evaluations as deemed necessary [13].
Otolaryngologist Approach
History
The medical history should begin at the patient’s birth, with questions covering mode of delivery, need for resuscitation, intubation or respiratory support, APGAR scores, and initial feeding strategies and outcomes. While these questions may not relate directly to laryngeal cleft, they help to develop a thorough differential diagnosis for children with feeding and/or breathing problems. The otolaryngologist should then follow the child’s development forward to the present, asking about immunization status, neurologic and motor developmental milestones, and feeding development . The clinician should also inquire about recurrent or persistent lower respiratory infections such as pneumonia or bronchitis, including frequency, most recent episode, associated hospitalizations, and need for antibiotic therapy. Specific questions can be tailored to the patient’s history based on the differential diagnosis listed earlier.
With regard to feeding, useful questions include current mode of feeding, type of bottle/nipple/cup used, and current textures being taken. The provider should ask about need for non-oral feeding such as nasogastric tube, gastrostomy tube, or parenteral nutrition. Any previous clinical or instrumental swallow evaluations should be reviewed, ideally by examining the actual images, and the provider should elicit any history of prior airway interventions such as intubation, tracheostomy, or other airway operations.
Our practice is also to ask about recurrent croup; clinical experience suggests that subglottic inflammation may be related to aspiration of secretions or refluxed material, which may be exacerbated by a laryngeal cleft.
Physical Examination
The otolaryngologist should perform a thorough head and neck and cranial nerve examination , particularly given the potential association of syndromic diagnoses with laryngeal cleft. In addition, chest auscultation and auscultation at the mouth may reveal subtle stridor or abnormal lower airway sounds.
In-Office Endoscopic Assessment
Flexible nasolaryngoscopy should be a routine part of the examination in patients with suspected laryngeal cleft. It serves two main purposes. First, it is a key part of FEES as described earlier. Second, it allows the otolaryngologist to rule out other diagnostic entities such as laryngomalacia, pooled secretions suggesting impaired sensation, and cranial neuropathies affecting the swallow or vocal fold motion. In some patients, the flexible endoscope may also be passed beyond the vocal folds to assess the subglottis or trachea. Our practice is to limit this to school-age children and older, as long as they are cooperative and can tolerate a weight-based dose of inhaled topical lidocaine to minimize risk of laryngospasm. However, other authors have successfully performed in-office tracheoscopy in younger children [14]. It is important to avoid the administration of any topical anesthetic into the nose or airway prior to FEES to avoid impairing sensation during swallow evaluation.
Flexible in-office endoscopy does not allow adequate visualization of the interarytenoid anatomy to rule laryngeal cleft in or out; indeed, flexible endoscopy by a skilled practitioner only detects this condition 69% of the time when the patient is under general anesthesia [15].
Operative Endoscopic Assessment
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