Custom-made intraoral mandibular distraction as treatment for neonatal airway obstruction

Abstract

Hypoplastic mandible related airway obstruction therapy may vary from non-surgical to surgical, depending on the severity of the obstruction. Since its introduction in 1992, distraction osteogenesis (DO) has been used to lengthen the mandible. A new intraoral device is presented here. It has no need of screw fixation, whilst placement and activation are intraoral, leading to simple placement and removal. Seven cases with hypoplastic mandible related airway obstruction were treated between 2001 and 2008 with intraoral DO at the authors’ institution. Six patients had a tracheostomy and one received continuous positive airway pressure (CPAP). After the distraction phase, five patients could be decanulated and in one case CPAP was no longer required. In one case the desired effect was not achieved. The findings suggest that early mandibular DO leads to damage to the permanent tooth buds resulting in missing teeth. The effectiveness of mandibular DO regarding early discharge of the patient is shown, leading to an overall cost reduction. Knowledge of alternative modalities such as mandibular DO in case of hypoplastic mandible related airway obstruction in neonatal healthcare should lead to early referral to a dedicated maxillofacial surgeon, possibly avoiding long-term airway support or tracheotomy.

Airway obstruction can be a side effect of mandibular hypoplasia in neonates. Owing to the micrognathia there is a reduced anterior mandibular projection which may lead to upper airway obstruction . The airway obstruction can vary from mild to complete obstruction, requiring emergency tracheotomy postnatally .

Depending on the severity, non-surgical therapy for neonatal hypoplastic mandible related airway problems consists of one or more of the following: prone/lateral sleep positioning, orthodontic treatment such as functional appliances and mandibular traction, oxygen supplementation, continuous positive airway pressure (CPAP) and nasopharyngeal tube. Surgical therapy may consist of glossopexy, subperiosteal release of the floor of the mouth, lengthening the mandible with distraction osteogenesis (DO) and tracheotomy .

Orthodontic treatment options are often not invasive and result in little or no scarring. Orthodontic appliances with or without velar extension such as a pre-epiglottic baton plate, do not seem suitable for patients with severe hypoxemia . A recent study shows positive results with a new oral extension appliance for patients with airway obstruction due to a tongue based obstruction seen in children with micrognathia of the mandible in Pierre Robin sequence . This technique may be less suitable for children without a tongue based obstruction.

Mandibular traction is another technique that has been reported to be useful, but a 2–6-week hospital stay with sedation and intubation throughout treatment is necessary . B aciliero et al. found that 10 of 118 children with an isolated Pierre Robin sequence treated with mandibular traction could be discharged after 10 days rather than the average 44 days .

A more invasive treatment is the nasopharyngeal tube. This modality has been used over the past 25 years, but throughout the intervention, children are forced to stay in the hospital . Severe cases often undergo tracheotomy early in life as an emergency procedure before they are presented to the maxillofacial surgeon. Morbidity (up to 29%) and mortality incidences (up to 3.3%) related to the tracheotomy have been reported.

In 1992, M c C arthy was the first to lengthen the mandible successfully using DO, providing a possible new solution for children with severe airway obstruction as a result of hypoplasia of the mandibula . Since then, many reports have been published on this treatment modality with good results .

Different DO devices, extraoral and intraoral have been used. The major advantages of extraoral devices are considered to be vector control and easy removal . Disadvantages are the scarring, the physical presence of the device and related problems (e.g. dislodgement of the device) and pin-site infection . Most intraoral devices require an additional extraoral approach .

Advantages of the intraoral devices are less conspicuous scarring, and fewer device related infections . Disadvantages are the more elaborate intervention needed for removal and the lack of vector control .

A new intraoral custom-made distraction device for the treatment of severe neonatal hypoplastic mandible related airway obstruction is presented. The device is placed, fixed and activated intraorally ( Fig. 1 ). There is no need for screw fixation, making the placement and removal simple. The primary aim of this study was to measure the effectiveness of treatment regarding the airway obstruction, measured as the removal of the airway support (either tracheostomy or CPAP). Complications as a result of the treatment were evaluated as secondary outcome.

Fig. 1
Distractor in situ in a 15-week-old patient.

Patients and methods

Since 2001, seven patients treated with the DO device for hypoplastic mandible related airway obstruction, have been evaluated. The local institutional Medical Ethical Review Board (MEC-2010-255) approved the research. Inclusion criteria were patients dependent on airway support with severe upper airway obstruction due to a hypoplastic mandible. Exclusion criteria were patients without hypoplastic mandible related airway problems and those with additional airway related problems (e.g. laryngotracheomalacy).

Prior to surgery the level of obstruction was determined using fibreoptic laryngoscopy. If the obstruction was located at the base of the tongue as a result of reduced anterior mandibular projection, and there were no other obstructions found at a lower level (e.g. laryngotracheomalacy), there was an indication for the treatment. A custom-made distractor was subsequently fabricated.

An impression of the mandible was taken and a plaster model made. On this plaster model the maxillofacial surgeon drew the osteotomy lines and the outline of the acryclic plate to be made. The model was sent to a specialized dental lab that constructs the custom-made distractor ( Fig. 2 ). Two activation screws are mounted onto the acrylic plate. Turning the screws 360° results in a distraction of 1 mm. The activation was directed anteriorly exiting the oral orifice thereby facilitating easy activation. A silicone tube covering the rods extending anteriorly protected the lips.

Fig. 2
DO system. 1: activation rod; 2: activation screw covered with silicone tube; 3: acrylic plate; 4: osteotomy site. The red lines indicate the circumferential wiring sites on both sides of the proximal mandible and in the symphysis region.

The patient received general anaesthesia in a supine position, and was ventilated using tracheostomy, if present, or naso-endotracheal intubation, whilst receiving intravenous antibiotics. A 2 cm incision was made over the alveolar process of the mandible in the (pre-)molar region on both sides. The mucoperiosteum was then locally elevated and the mental nerve was identified on both sides. A bilateral corticotomy of the mandible was performed both buccal and lingual. Care was taken not to damage the alveolar nerve or tooth buds. In the last three patients piezo-electric surgery was used instead of the oscillating saw. On completing the corticotomy the incision was closed using vicryl 4/0. The distractor was placed and fixated using a circumferential wiring technique with a hypodermic needle on both sides of the proximal mandible and in the symphysis region ( Fig. 2 ). To protect the mucosa, silicon tubes were placed around the activation rod ( Fig. 2 ). The distractor was tested before the surgery ended. The whole procedure takes 60 min on average with a blood loss of less than 50 cc in all cases. Removal required a short general anaesthesia and prophylactic antibiotics, in a day-care setting, consisting of cutting the wires and removing the distractor. The intervention took 5 min.

Distraction protocol

Distraction of the mandible began 2–3 days after surgery. The device was activated twice a day for a total of 360° resulting in a distraction of 1 mm daily. When the patient proved to be tracheostomy or CPAP independent an overcorrection of 3–5 mm was performed before ending the distraction phase. A consolidation phase was maintained (on average 6 weeks) before the distractor was removed.

Results

The study group consisted of four males and three females: four with Pierre Robin sequence, one with Miller Syndrome, one with Treacher Collins and one without definitive diagnosis ( Table 1 ). Ages ranged between 9 and 84 weeks. Six patients had a tracheostomy preoperatively and one patient was dependent on CPAP. All patients were hospitalized from, or shortly after, birth until the treatment.

Table 1
Patient data.
Patient Sex Diagnosis Preoperative airway support Age at surgery (weeks) Complications Successful regarding airway Follow-up time (years)
1 M Miller syndrome Tracheotomy 16 Open bite,
Missing
34, 35, 44, 45
Yes 9
2 M PRS Tracheotomy 19 Missing
34, 35, 44, 45
Yes 7
3 F Treacher Collins Tracheotomy 83 Abscess
Removal 74, 84
Missing 35, 46
Yes 6
4 F PRS Tracheotomy 17 Yes 5
5 M PRS Tracheotomy 12 Yes 3
6 M Unknown Tracheotomy 10 Open bite No 3
7 M PRS CPAP 12 Removal 74 Yes 2
M, male; F, female; PRS, Pierre Robin sequence; CPAP, continuous positive airway pressure.

During the distraction phase, five of the six patients with a tracheostomy were successfully decanulated. One patient dependent on CPAP was able to discontinue this treatment after distraction. Three patients were discharged from hospital whilst the distractor was in situ . The consolidation phase ranged from 5 to 10 weeks. In all patients the feeding was undisturbed during the distraction and consolidation phase. The average distraction distance was 24 mm (range 19–32 mm).

The follow up ranged from 5 to 9 years. Figures 3–6 provide clinical examples with 7 years of follow-up. There were no nerve disorders in the patient group.

Jan 26, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Custom-made intraoral mandibular distraction as treatment for neonatal airway obstruction
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