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Contents lists available at ScienceDirect

International Journal of Pediatric Otorhinolaryngology journal homepage: www.elsevier.com/locate/ijporl

Review Article

Pierre Robin sequence: Review of diagnostic and treatment challenges Aurore Coˆte´ a,*, Amanda Fanous b, Athari Almajed a,1, Yole`ne Lacroix b a b

Respiratory Medicine Division, The Montreal Children’s Hospital, Montreal, Canada Otolaryngology – Head and Neck Surgery Division, The Montreal Children’s Hospital, Montreal, Canada

A R T I C L E I N F O

A B S T R A C T

Article history: Received 31 October 2014 Received in revised form 29 January 2015 Accepted 30 January 2015 Available online xxx

Pierre Robin sequence is not a rare condition and paediatric specialists caring for respiratory related issues are likely to encounter cases in their practice. There have been a few recent reviews on the topic, mostly focusing on the surgical interventions performed for cases with severe airway obstruction. In the present review, we will highlight the different challenges that remain today in the global evaluation of infants afflicted with this condition through a thorough review of the medical literature, giving the clinician a full scope of the disease and of the various management options. The need for an improved objective evaluation of airway obstruction and for a better classification will be emphasized. We are therefore proposing a novel classification scheme that will better account for respiratory and feeding difficulties in these infants. Finally, many knowledge gaps persist regarding this condition, underlining the necessity for further research both in the genetic field and regarding the outcome of therapy. ß 2015 Published by Elsevier Ireland Ltd.

Keywords: Classification Airway obstruction Mandibular distraction Tongue–lip adhesion Nasopharyngeal airway Polysomnography

Contents 1. 2. 3.

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Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pathophysiology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Clinical manifestations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Airway obstruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1. Feeding difficulties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2. Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1. Anatomical airway evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . Objective evaluation for airway obstruction . . . . . . . . . . . . . . . 4.2. Other objective evaluations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3. Feeding evaluation. . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.1. Oesophageal function and gastro-oesophageal reflux 4.3.2. Genetic investigation . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.3. Classification of Pierre Robin sequence. . . . . . . . . . . . . . . . . . . . . . . . . Classification of Caouette-Laberge . . . . . . . . . . . . . . . . . . . . . . . 5.1. Classification of Cole. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2. Management of airway obstruction . . . . . . . . . . . . . . . . . . . . . . . . . . . Non-surgical options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1. Positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1.1. Nasopharyngeal airway . . . . . . . . . . . . . . . . . . . . . . . . 6.1.2. Continuous positive airway pressure (CPAP) . . . . . . . 6.1.3. Orthodontic apparatus. . . . . . . . . . . . . . . . . . . . . . . . . 6.1.4.

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* Corresponding author at: Respiratory Medicine Division, The Montreal Children’s Hospital, 2300 Tupper, D-380, Montreal, Canada H3H 1P3. Tel.: +1 514 412 4444; fax: +1 514 412 4364. E-mail address: [email protected] (A. Coˆte´). 1 Present address: The Pediatric Pulmonology Division at Mubarak Al Kabeer Hospital, Kuwait. http://dx.doi.org/10.1016/j.ijporl.2015.01.035 0165-5876/ß 2015 Published by Elsevier Ireland Ltd.

Please cite this article in press as: A. Coˆte´, et al., Pierre Robin sequence: Review of diagnostic and treatment challenges, Int. J. Pediatr. Otorhinolaryngol. (2015), http://dx.doi.org/10.1016/j.ijporl.2015.01.035

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Surgical options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tongue–lip adhesion (TLA) . . . . . . . . . . . . . . . . . . . 6.2.1. Subperiosteal release of the floor of the mouth . . . 6.2.2. Mandibular distraction osteogenesis . . . . . . . . . . . 6.2.3. Tracheostomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.4. Management of feeding issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Feeding problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1. Swallowing dysfunction and feeding-facilitating technique . 7.2. 7.3. Gastro-oesophageal reflux . . . . . . . . . . . . . . . . . . . . . . . . . . . Outcomes in PRS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Relief of airway obstruction . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1. 8.2. Mandibular growth and airway changes . . . . . . . . . . . . . . . . Outcome of feeding issues . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3. Developmental outcome. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4. Gaps in knowledge and future research avenues . . . . . . . . . . . . . . . 9.1. Genetics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Objective documentation of airway obstruction . . . . . . . . . . 9.2. Feeding issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.3. Developmental outcome. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4. Suggestion for classification of Pierre Robin sequence. . . . . . . . . . . Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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1. Introduction

2. Pathophysiology

Pierre Robin sequence (PRS) refers to the association of micrognathia, glossoptosis, and airway obstruction. Typically, a wide U-shaped cleft palate is also associated with PRS; in large series, a cleft palate is reported in up to 73–90% of cases [1– 5]. Descriptions of cases of micrognathia and cleft palate have been published since the 19th century in the English medical literature (reviewed in Randall et al. [6]). Pierre Robin first described the treatment of mandibular hypoplasia both in children and in adults in 1923 [7] in the French medical literature but his first description of the condition that now bears his name was not published until 1934 [8]. The incidence of PRS, derived from population-based studies, varies from country to country with the highest incidence in the United States with one case/3120 live births (one case/5480 live births for isolated Pierre Robin sequence, derived from a survey involving 44 states) [9]. In other countries, the incidence varies from one case/8060 live births in Germany [10], to one case/8500 in the UK [11], to one case/14,000 in Denmark [12]. These variations might be explained by the fact that the data was collected at different time periods over five decades and different methods were utilized. Other anomalies are associated with PRS and may appear in conjunction with a recognized syndrome. From large series, it is reported that approximately 50% of PRS cases are syndromic [1,13,14] and the three most common syndromes (accounting for 65% of the syndromic cases) are Stickler (the most frequent), velocardiofacial and Treacher-Collins [1,13–18]. In a recent comprehensive review by Tan et al. [19], more than 50 syndromes have been described in association with PRS. Mortality rates for PRS have been published from various countries (Canada [1], United Kingdom [11], Unites States [5] and The Netherlands [20]) over time. It was found to lie between 3.6% and 21%. Infants with associated anomalies or syndromic cases have a higher mortality. In the most recent study published from a group in the United States (data from 2001 to 2012, 181 infants, average follow-up 35 months) [5], the overall mortality rate was 16.6% with no mortality in isolated PRS. Infants with cardiac or central nervous system anomalies had the highest mortality (respectively 39% and 33%).

The exact cause and the pathophysiology of Pierre Robin sequence are still unknown despite significant progress in the last decade. SOX9 gene, a critical chondrogenic regulator, has been linked to nonsyndromic PRS in families with more than one member affected [21]. Furthermore, more recent work has shown that multiple non-coding elements contribute to the craniofacial regulation of SOX9 expression; in PRS, these craniofacial regulatory elements are the site of deletions, contributing to the typical phenotype [22]. The most frequent syndromic PRS patients have different genes involved: Stickler syndrome is associated with mutations in COL genes (COL2A1, COL9A1, COL11A1, and COL11A2, reviewed by Acke et al. [23]); velocardiofacial syndrome arises from a microdeletion of chromosome 22q11.2 [24]; and Treacher Collins syndrome is associated with mutations in the TCOF1, PLOR1C, and POLR1D genes [24–26]. There are three major hypotheses to explain the sequence of events in PRS [19]: (a) hypoplastic mandible; (b) oropharyngeal and muscular deficiencies; (c) compression of the mandible in utero. The hypoplastic mandible theory is the one mostly retained in the literature and the one that has been demonstrated in animal models (mostly murine) [27–29]. The primary defect is thought to be in Meckel’s cartilage, the embryonic structure involved in the formation and growth of the mandible. The subsequent mandibular hypoplasia is thought to lead to a small mouth volume, abnormal position of the tongue, and the secondary impairment of palatal closure [30]. In the oropharyngeal and muscular deficiency hypothesis, it is believed that hypotonia of the oropharyngeal muscles could result in hypoplasia of the mandible (reviewed in Tan et al. [19,31]). The persistence of feeding issues for weeks to months in infants afflicted with PRS in which respiratory compromise has resolved suggests anomalies in pharyngeal tone and motility. Foetal oral muscular activity, including swallowing movements, is thought to be required for normal growth of the mandible. Interestingly, many conditions characterized by hypotonia are also associated with PRS (congenital myotonic dystrophy, for instance). Finally, the mandible compression theory probably plays a role in a small proportion of infants born with PRS, in particular those having experienced a pregnancy associated with foetal constraint

Please cite this article in press as: A. Coˆte´, et al., Pierre Robin sequence: Review of diagnostic and treatment challenges, Int. J. Pediatr. Otorhinolaryngol. (2015), http://dx.doi.org/10.1016/j.ijporl.2015.01.035

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such as oligohydramnios or twin pregnancies. Indeed, a higher incidence of twins has been reported in PRS when compared to the general population [15,32]. 3. Clinical manifestations Infants born with PRS, as previously described, will often display on physical examination the classical micrognathia and glossoptosis. However, more importantly for both the clinician and the caregiver, these infants will have a variable degree of airway obstruction and feeding difficulties. 3.1. Airway obstruction Pierre Robin sequence is characterized by varying degrees of upper airway obstruction (with or without hypoxaemia) leading to feeding and growth problems. Airway obstruction can occur spontaneously or with feeding, during wakefulness as well as during sleep. Snoring, a cardinal manifestation of airway obstruction in children and adults, is not always present in infants with PRS. Anderson et al. [33] reported that only 50% of the infants with severe airway obstruction had snoring. Progressive airway obstruction may become more noticeable in the second month of life [34]. This emphasizes the importance of serial airway evaluations during the first few months of life in order to detect significant or worsening airway obstruction. Recent studies with polysomnographic evaluation for obstructive sleep apnea report a high incidence of airway obstruction of various severities, before any intervention is performed, with mild sleep apnea cases being the exception. Indeed, Anderson et al. [33] reported on 11 infants evaluated by polysomnography in the first two months of life, and all had airway obstruction with only one with a mild degree. Similarly, Daniel et al. [35] reported on 39 infants studied with polysomnography between 5 and 141 days of age; five (12.8%) had mild obstruction, five (12.8%) had moderate obstruction, and 29 (74.4%) had severe obstruction. 3.2. Feeding difficulties Feeding difficulties are thought to be secondary to both the airway obstruction and the associated cleft palate that prevents the formation of adequate negative intraoral pressure required for the extraction of milk from the breast or the bottle. The initiation of oral feeding in infants requires that the control of sucking, swallowing, and respiration be well integrated and coordinated at the central level [36]. The sequence of the oral, pharyngeal, and oesophageal phases of swallowing must be coordinated with respiration in order to avoid aspiration. Feeding difficulties are not uncommon in PRS. In some cases, initiation of normal oral feeding might be impossible. Failure to thrive can therefore result from poor caloric intake or from the increased respiratory efforts leading to the subsequent increased energy expenditure. Many authors report that 40–70% of cases of PRS need nasogastric tube feeding for up to several months [17,37–40] many even resort to gastrostomy tube feeding [13,41]. The prevalence and severity of feeding difficulties are higher in syndromic cases compared to isolated PRS cases [37,40,41], likely resulting from associated neurological or cardiovascular problems. There is, however, a proportion of infants presenting with feeding difficulties in the absence of any airway obstruction [42] or even after its correction (27% in one study) [31]. Gastro-oesophageal reflux (GER) is also prevalent in PRS [13] and can complicate airway obstruction [43]; in addition, GER has been identified as a risk factor for failure of some therapeutic strategies [44–46]. Infants who have acid reflux to the upper airway can develop reflux laryngitis that will contribute to

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worsening of the airway obstruction [47,48]. The prevalence of abnormal GER was reported to be as high as 80% in some studies [49,50] often improving with improvement of airway obstruction [51]. Oesophageal dysfunction might also complicate PRS. This has been evaluated more specifically by electromyography and oesophageal manometry. Baudon et al. [52] evaluated 28 infants with non-syndromic PRS with sucking-swallowing electromyography and oesophageal manometry. They found dysfunction in the motor coordination of the tongue, the pharyngeal muscles and the oesophagus. Similar results were also found by Baujat et al. [53] who studied oesophageal manometry in 35 infants with PRS; in the author’s opinion, the manometry pattern in these infants with isolated PRS suggested a defect in the central control of oesophageal motility. 4. Evaluation 4.1. Anatomical airway evaluation Airway obstruction at the level of the tongue base is the hallmark of PRS, but other airway anomalies have also been described. The largest series evaluating the incidence of associated airway anomalies was published by Andrews et al. [54] In their series of 133 infants, 23 (17%) had associated airway anomalies, the most frequent anomaly being laryngomalacia (twelve cases, often also associated with tracheomalacia). They also describe the presence of a tracheal web (five cases), vocal cord paralysis or mass (three cases), epiglottal collapse (two cases) and infraglottal narrowing (one case, the precise nature of the infraglottal narrowing, whether pertaining to a subglottic stenosis or a lower airway anomaly, was not mentioned). However, lower airway anomalies were identified in 11 of the 133 infants (8.2%). This proportion of lower airway pathology is similar to that reported by Cruz et al. [42] (8.5%, mostly tracheomalacia). Other anomalies described infrequently with Pierre Robin sequence include choanal atresia/stenosis and hypoplastic epiglottis [55]. In addition, Knapp et al. [56] have reported, in a small series of infants with PRS (15 infants), that 75% needed an endotracheal tube smaller than what was expected for their age and size. However, this finding, suggestive of subglottic stenosis, still needs further confirmation by a larger series. The associated airway anomalies highlight the necessity of a careful evaluation of the upper airway with nasolaryngoscopy in all infants with PRS. Flexible nasolaryngoscopy is a procedure performed in the Otolaryngology clinic setting using a minimal amount of topical anaesthesia. The assessment should thoroughly evaluate the upper airway, starting in the nose, then the choanas, the pharynx, including the tongue base, and finally the larynx. Ideally, the tongue base obstruction should be evaluated in both prone and supine positions. As well, the evaluation in a semiupright or an elevated side-lying position would be useful in order to determine the optimal position for feeding. The small but significant percentage of lower airway involvement implies that a rigid and/or flexible bronchoscopy should be considered: (a) prior to an already scheduled non airway related surgical procedure; (b) prior to surgical correction of tongue base obstruction in cases where non-invasive management fails; and (c) in cases of persistent obstruction despite surgical correction of tongue base obstruction. This procedure will assess the subglottis, trachea and bronchi. Flexible and rigid bronchoscopies are performed in the operating room under general anaesthesia, ideally with spontaneous ventilation. Sleep endoscopy in the operating room setting may also be considered. Sleep endoscopy can be described as nasolaryngoscopy performed in a drug-induced sleep state allowing for a more

Please cite this article in press as: A. Coˆte´, et al., Pierre Robin sequence: Review of diagnostic and treatment challenges, Int. J. Pediatr. Otorhinolaryngol. (2015), http://dx.doi.org/10.1016/j.ijporl.2015.01.035

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physiologic and dynamic evaluation of the entire upper airway during sleep. This examination helps determine the precise site(s) of collapse during inspiratory efforts [57,58]. The indications would be similar to those for bronchoscopy and could be useful (a) to assist in surgical planning; and (b) in cases of persistent obstruction despite surgical correction of the tongue base obstruction, suggesting a second source of obstruction. Nonetheless, to date, the use of sleep endoscopy in patients with PRS has not been described in the medical literature as it has for patients with Trisomy 21 [59,60], for instance. 4.2. Objective evaluation for airway obstruction In addition to the endoscopic evaluation, which is aimed at identifying the anatomy and the potential sites of airway obstruction, objective data (related to oxygenation and gas exchange) should always be collected in patients with PRS in order to quantify the degree of obstruction and the presence of significant hypoxaemia and hypercapnia. Indeed, the presence of airway obstruction has been documented in a significant proportion of infants that are thought to be asymptomatic [29,30]. It is generally agreed that estimation of the Hb-O2 saturation in the arterial blood by pulse oximetry (SpO2) and the measurement of capillary PCO2 are an essential first step. Most centres will record SpO2 for one night and analyze the data as the percentage of time spent under the 90% limit. Unfortunately, although normative values are published in the literature, it is not useful for the youngest infants with airway obstruction. Indeed, the published normative data for drops in SpO2 cannot separate the contribution of central from obstructive events accounting for the time spent below a SpO2 value of 90% [61]. It is well known that young infants (first few months of life) have central pauses in breathing associated with drops in SpO2 and this could be recurrent as part of periodic breathing (Poets et al. [62], Hunt et al. [63,64]). Therefore, in the presence of repetitive drops in SpO2, even in infants that do not seem very symptomatic, a polysomnography is recommended if available. If the test is not readily available, an overnight recording of respiratory movements combined with pulse oximetry would help determine whether the drops in SpO2 are due to central apnea. In the absence of significant central apnea, it could be assumed that all the drops in SpO2 are secondary to airway obstructions. As for PCO2, it is well known that repeated airway obstruction in young infants, even if partial, will lead to elevated PCO2 [65]. It is therefore a very good test to follow longitudinally in the first few months of life. Polysomnography is the gold standard for the diagnosis of airway obstruction. Normative data for obstructive apnea in infants have been determined to be between 0.6 and 2 events/h of sleep in infants aged between 0 and 2 months and between 0.4 and 1 events/h for infants aged 5–6 months. The values decrease to less than 0.5 event/h after one year of age (reviewed in Katz et al. [66] and Ng and Chan [67]). The data included the study of Kato et al. [68] on 1023 infants divided into 5 different age groups in the first 6 months of age. In addition, Brockmann et al. [61] have provided data in 37 healthy infants showing at one and three months of age that the 95th percentile corresponds respectively to 5.8 and 3.4 mixed obstructive apnea and hypopnoea/hour. As per the American Academy of Sleep Medicine, for all ages (except for very young infants) [69], a mild degree of obstructive sleep apnea corresponds to an apnea index >1 and 5 and

Pierre Robin sequence: review of diagnostic and treatment challenges.

Pierre Robin sequence is not a rare condition and paediatric specialists caring for respiratory related issues are likely to encounter cases in their ...
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