Internal mandibular distraction to relieve airway obstruction in children with severe micrognathia

Abstract

Congenital craniofacial malformations such as Pierre Robin sequence or Treacher Collins syndrome are associated with mandibular micrognathia, resulting in obstructive sleep apnea (OSA) due to a decreased pharyngeal airway; in severe cases this leads to tracheostomy dependence. We present a series of 18 patients in whom we performed mandibular lengthening using internal distraction devices to relieve airway obstruction. Seven were tracheostomy-dependent and 11 were respiratory distressed without tracheostomy. The mandible was distracted at a rate of 1 mm per day. Following 3 months of consolidation for bony maturation, the distraction devices were removed. Results demonstrated forward mandibular elongation of a mean 22 mm (range 20–25 mm) and an increase in SNB angle and in pharyngeal airway. All patients with tracheostomies were decannulated, and there was an improved airway with resolution of signs and symptoms of OSA and elimination of oxygen requirement in all patients. We conclude that mandibular distraction using internal devices is a useful and comfortable method for younger children to expand the mandible forward and increase the pharyngeal airway.

In recent years distraction osteogenesis has become the treatment of choice for paediatric obstructive sleep apnea (OSA) patients with Pierre Robin sequence, Treacher Collins syndrome, and other syndromes that are associated with a hypoplastic mandible, glossoptosis, and airway obstruction. Many patients suffer from respiratory distress and in severe cases are tracheostomy-dependent.

Mandibular advancement for the treatment of OSA was initially performed with bilateral external devices. The main drawbacks of external devices are inconvenience to the patient over several months of treatment and exposure of the device to external trauma that may lead to pin loosening and shortening of the retention period and subsequently to increased relapse. Also, external devices leave visible scars, as the pins track through the skin. However, with the popularization of the distraction method for the treatment of OSA, internal small distraction devices have also been used.

In this study we present our experience of the treatment of OSA in a paediatric population with mandibular micrognathia by mandibular lengthening using internal distraction devices.

Materials and methods

Eighteen patients aged between 6 months and 14 years with craniofacial anomalies associated with a hypoplastic mandible and glossoptosis, including Pierre Robin sequence, Treacher Collins syndrome, and Goldenhar syndrome, were included in this study. As a result of their conditions, these patients had symptoms of OSA. Eleven patients suffered from respiratory distress and were tracheostomy candidates, and seven more severe cases were tracheostomy-dependent ( Fig. 1 ). All patients underwent endoscopy prior to the decision for distraction to fully evaluate the airway and to ensure that the patient did not suffer from tracheomalacia or other problems that could not be corrected with distraction.

Fig. 1
A 7-month-old girl with Pierre Robin sequence associated with severe mandibular hypoplasia and obstructive sleep apnea with a permanent tracheostomy.

Polysomnography was performed on all children before treatment and after completion of distraction. Prior to treatment, oxygen saturation was between 74% and 80% (mean 77%) and the apnea index (the respiratory disturbance index, RDI) was over 20. Preoperative and postoperative lateral cephalograms were used to measure and compare the posterior airway space (PAS, mm) and the sella–nasion–B point (SNB) angle. The lateral cephalometric radiographs revealed mandibular hypoplasia that caused retroposition of the base of the tongue and inadequate pharyngeal space.

Head and neck computed tomography (CT) in axial and sagittal planes ( Fig. 2 ) and three-dimensional reconstructions ( Fig. 3 ) were performed before and after treatment. CT was used to measure the airway sagittal length (in mm) at the C2 level, to gain an appreciation of the severity of the airway obstruction, to assess the mandibular deficiency, and to contribute to the planning of the operation.

Fig. 2
(A) Sagittal and (B) axial CT views showing significant airway compromise (arrow).

Jan 19, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Internal mandibular distraction to relieve airway obstruction in children with severe micrognathia
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