Subperiosteal release of the floor of the mouth musculature in two cases of Pierre Robin sequence.

Abstract

Many management approaches have been considered to relieve upper respiratory obstruction in patients with Pierre Robin sequence, but the choice of treatment is determined by the severity of the obstruction. These options include prone positioning, the use of a nasal trumpet, and surgery. One surgical technique is the subperiosteal release of the floor of the mouth musculature. The theory behind this procedure is that this musculature is under tension, and therefore it pushes the tongue upward and backward, resulting in respiratory obstruction. In theory, the release of this musculature from the mandible should alleviate the tension and hence clear the obstruction. In an attempt to objectively evaluate this theory, we performed subperiosteal release surgery on two infants. Our first patient required an emergent tracheostomy on postoperative day 2 because of the onset of surgically induced airway edema. To avoid this complication in the second patient, we performed a tracheostomy at the same time as surgery. Pr e-and postoperative magnetic resonance imaging in the second patient revealed only a minimal change in the anatomy of the floor of the mouth musculature. We believe the subperiosteal release of the floor of the mouth musculature requires further evaluation before it can be considered to be effective in the surgical treatment of respiratory obstruction in Pierre Robin sequence.

Introduction

Pierre Robin sequence (i.e., syndrome) is a rare condition that affects infants. It is associated with a cleft palate and consists of micrognathia, glossoptosis, and varying degrees of airway obstruction. [1] Its incidence is 1:8,500. [2] C

Clinically, there is a wide variation in the manifestation of airway obstruction. Symptoms subside as infants develop physically (mandibular growth) and neurologically (improved control of the tongue musculature). [3] The management of airway obstruction should be approached in a stepwise fashion. Many approaches have been considered, but the choice of treatment is determined by the severity of the obstruction. The most benign intervention is to position the infant in the prone position. If prone positioning does not solve the problem, a nasopharyngeal airway or nasogastric tube can be inserted. A more aggressive approach is to perform surgery to hold the tongue forward (glossopexy). Finally, if all else fails, it might be necessary to perform a tracheostomy.

Feeding difficulties pose a particular challenge for physicians and parents of infants with Pierre Robin sequence. Again, prone positioning might solve the problem, and specially designed feeding bottles and nipples can be used. If these options prove to be inadequate, a nasogastric or gastric tube might be necessary.

Many researchers have proposed hypotheses for the cause of the airway obstruction in Pierre Robin sequence. According to a theory by Epois, the musculature of the floor of the mouth is under increased tension, and it pushes the tongue upward and backward, causing respiratory obstruction.[4] Epois proposed that the imbalance of the muscular insertion of the tongue on the mandible is responsible for the micrognathia, tongue elevation, and glossoptosis in these patients. If this is indeed the case, the subperiosteal release of the floor of the mouth musculature during infancy should allow the tongue to return to a more normal position, thus relieving the obstruction. [5]

The purpose of this article is to describe our objective evaluation of this surgical technique in two cases, one of which involved the use of magnetic resonance imaging (MRI) to compare the pre- and postoperative anatomy of the floor of the mouth musculature.

Case reports

We performed subperiosteal release surgery on two infants with Pierre Robin sequence: a girl aged 2.5 months and a boy aged 3 months. Surgery was performed under general anesthesia with endotracheal intubation. A 2-cm submental incision was made through the mandibular periosteum. Dissection was performed subperiosteally on the medial side of the mandible from angle to angle. (Following dissection, it should be easier to depress the tongue and the floor of the mouth.) The incision was then closed.

The female patient required an emergent tracheostomy on postoperative day 2 as a result of self-extubation and our inability to reintubate because of surgically induced airway edema. She was decannulated at 10 months of age.

To prevent this complication from occurring in the male patient, we performed a tracheostomy in addition to the subperiosteal release. We also obtained an MRI preoperatively and on postoperative day 14 (figure). When we compared the two MRIs, we saw only minimal differences in the anatomy of the floor of the mouth. The boy remained tracheostomy-dependent until he reached 21 months of age.

Discussion

An understanding of the pathophysiology of upper airway obstruction in Pierre Robin sequence is important. Among the possible causes of upper airway obstruction are the posterior displacement of a normal-sized tongue secondary to micrognathia and/or retrognathia, the loss of support of the genioglossus muscle, and negative pressure in the pharynx during swallowing and inspiration. [6]

Sher described four different types of upper airway obstruction. [7] Type 1 is caused by an anteroposterior obstruction secondary to the posterior movement of the dorsum of the tongue to the posterior pharyngeal wall. In type 2, the tongue, velum, and posterior pharyngeal wall collapse the upper oropharynx. In type 3, the lateral pharyngeal walls move medially to appose one another. In type 4, the pharynx constricts circumferentially. In a study of 53 cases of Pierre Robin sequence, Argainaso found that types 2, 3, and 4 obstruction required tracheostomy. [8] Bath and Bull found tracheostomy to be the safest method of managing upper airway obstruction. [9] Although pediatric mortality caused by tracheostomy has dramatically decreased over the years and home care for longterm management of tracheostomies is accepted, the procedure still carries a significant risk of morbidity and mortality.

Douglas in 1946 reported on his laryngoscopic examination of infants with Pierre Robin sequence. [10] He felt that the micrognathia caused the tongue to ball valve in the hypopharynx on inspiration, and that this situation worsened when the patient was supine. He described a glossopexy procedure that anchored the tongue forward and that was successful in 100% of 25 cases. [11] Routledge reported that this procedure carries the risk of several complications, including tongue lacerations, wound infections, dehiscences, injuries to the submandibularducts, and scar deformations of the lip, chin, and floor of the mouth. [12]

Epois hypothesized that the primary cause of retrognathia and abnormal tongue position is the imbalance of the muscular insertion of the tongue on the mandible. [4] This imbalance causes only a temporary restrictive phenomenon; it does not represent a permanent mandibular condition because the problem usually resolves with mandibular growth. Delorme et al hypothesized that the release of this musculature during infancy should allow the tongue to return to a more normal position. [5] Caouette-Laberge et a1 found that following release, the tongue finds a more favorable point of equilibrium, and the detached muscles reinsert in their new location. [13] However, in the male patient on whom we performed MRI, we found only a minimal change in the anatomy of the floor of the mouth musculature between the pre- and postoperative images. More important, this patient was not able to tolerate the capping of his tracheostomy tube following the subperiosteal release of the musculature.

Although Caouette-Laberge et a1 found that the subperisoteal release technique carried minimal morbidity, [13] our female patient required an emergent tracheostomy following self-extubation in the intensive care unit. We were unable to reintubate her because of airway edema.

The obvious limitation of our study is that it involved only two patients. Also, some might argue that we did not postoperatively stent open the pharyngeal airways in our patients. However, the reason we did not is that Caouette-Laberge et a1 found that alleviating the tension of the tongue was all that was required, and that intubation until postoperative day 5 or 6 is necessary only to allow airway edema to subside. [13]

We believe that the subperiosteal release of the musculature of the floor of the mouth requires further evaluation before it can be considered to be an effective surgical treatment of respiratory obstruction in patients with the Pierre Robin sequence.

From the Department of Pediatric Otolaryngology (Dr. Siddique and Dr. Haupert) and the Department of Pediatric Plastic Surgery (Dr. Rozelle), Children's Hospital of Michigan, Wayne State University, Detroit.

References

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