Silent Sinus Syndrome: A Paediatric Condition Diagnosed in the Orthodontic Department

Case report

A 7-year-old boy was referred to the autotransplantation multidisciplinary team for an assessment for premolar transplantation to replace his poorprognosis upper central incisors. The patient had previously sustained a fall from his bicycle onto a pavement at the age of 6. During this, he avulsed his upper central incisors. The patient was seen by the oral and maxillofacial team in A&E, and he presented with an extraalveolar dry time of 1.5 hours, as well as apical root fractures of both teeth. The upper central incisors were replanted. The patient was advised regarding their poor prognosis, including risks of infection and resorption.

As part of the assessment for autotransplantation and orthodontic treatment, an OPT radiograph (Figure 2) was taken to assess the presence of unerupted teeth and root lengths. A CBCT (Figure 3) was taken to assess the root development and any curvature of potential donor teeth. The OPG and CBCT demonstrated a diminutive and completely opacified left maxillary antrum. No gross inferior displacement of the left orbital floor was demonstrated. This was felt to most likely represent a hypoplastic antrum with mucosal thickening; however, silent sinus syndrome or a more aggressive soft tissue mass could not be entirely excluded. On questioning, the patient did not report experiencing any sinus symptoms. There was no nasal blockage, discharge or pain. His sense of smell and taste was normal, and he had no eye symptoms. On examination, there was no facial asymmetry or enophthalmos. After gaining consent, the patient was then referred to ENT.

ENT clinical assessment confirmed no asymmetry to palpation in the maxillary area and no asymmetry related to his eyes. Anterior rhinoscopy was within normal limits and fibre-optic nasal endoscopy demonstrated that the septum was deviated into the area of the left middle meatus. There was no evidence of a mass, polyposis or discharge of the middle ear meatus. A CT sinus (Figure 4) confirmed SSS. The patient and parent were informed that although it was asymptomatic, there was a risk that, as the patient's mid-face grew, his un-aerated left maxillary sinus would grow at a lesser rate than the right. This can result in facial asymmetry andenophthalmos. Following discussions of advantages, disadvantages and risks with the patient and the parent, the patient was listed for a functional endoscopic sinus surgery (FESS) in addition to dental treatment. FESS involves the opening of the sinuses under direct visual assessment using minimally invasive techniques.⁹

Discussion

There is a paucity of case reports on SSS in prepubescent patients. Looking at the findings of a systematic review on SSS, out of the 153 articles included, only 12 featured paediatric cases (Table 1).⁷ Of these 12 cases, two reported SSS in children as young as 7-years-old. Chang et al described a case of a symptomatic 7 year old who attended due to headaches⁴ and Petraroli et al described a case of a finding of SSS in a patient with William's syndrome.¹⁰ Fonseca et al highlighted a case where a patient was referred to ophthalmology as a result of a unilateral divergent squint and poor vision since childhood. The orbital MRI picked up the signs of SSS. Although this patient had an endoscopic maxillary antrostomy, visual acuity and ocular motility were unchanged.¹¹ This case report is the second SSS finding during a dental assessment. In the first case report, Leidens et al described a similar case in a patient who presented to the orthodontic department with enophthalmos (posterior displacement of the eyeball) and hypoglobus (downward displacement of the eyeball) alongside opacification of the maxillary sinus on the OPG. This was further confirmed with CBCT imaging that showed osteomeatal obstruction with bone deformity.¹² This finding on the CBCT report shows the importance of careful assessment of any radiographic imaging as part of the patient assessment.

An OPG is an indispensable part of patient assessment to evaluate the dentition. It is vital to appropriately assess the maxillary sinus, which forms part of this image, based on the dimension requested. Clinicians should aim to identify six key structures on the panoramic radiograph to aid in the identification of maxillary sinus pathology:¹³

Figure 2 shows the initial radiopaque changes of the left maxillary sinus of the patient above and outlines the key structures described above. This case highlights the importance of fully assessing OPT radiographs for incidental findings, including assessment of the sinus. When carrying out adjunct imaging such as CBCT imaging, clinicians must always ensure:

In the above case, CBCT imaging was vital to assess root length and development. Research has shown that CBCT imaging increases the treatment predictability in autotransplantation cases.^15,16,17,18 In this instance, the CBCT imaging enabled an additional diagnosis. It is prudent to consider how further changes in guidance on the use of CBCT may identify other incidental findings.

It is, therefore, also vital to consider the differentials for sinus opacifications. The flowchart (Figure 5) summarizes nine differential diagnoses that may cause changes to normal radiographic sinus anatomy. Some common examples are sinusitis (the most common), odontogenic cysts, mucoceles and mucous retention cysts. Some less common differential diagnoses include benign neoplastic disease such as an inverted papilloma (the most common benign neoplasm of the paranasal sinuses) or malignant changes that can cause a radiopaque appearance of the maxillary sinus.^27,28,29,30 A full orthodontic assessment includes an analysis of facial asymmetry. As described, SSS can sometimes present as skeletal asymmetry. It is vital to consider the potential causes of facial asymmetry aside from the normal relative asymmetry prevalent in approximately 21–85% of the population.³¹ Lastly, this case involved the orthodontic, paediatric, ENT and OMFS departments, highlighting the importance of interdisciplinary management.³²

Conclusion

Although SSS is commonly diagnosed in the adult population,^4,5,6 this case highlighted the importance of appropriate assessment and differential diagnoses of paediatric patients presenting with similar symptoms. Facial asymmetry assessment is routine for all orthodontic patients. Although the child in this case did not present with facial asymmetry, it highlights the importance of an appropriate differential diagnosis, such as SSS, if presented with enophthalmos or facial asymmetry. Radiographic assessment is a vital addition to clinical assessment to aid treatment planning. It is essential to carry out thorough analysis and reporting of any radiographs taken. This case highlighted the importance of appropriately reporting on images within a clinician's scope and referring externally for reports when required. There is an increasing use of CBCT imaging to aid appropriate treatment planning in dentistry;³³ this may increase incidental findings, such as SSS, and aid appropriate early diagnosis and management. Furthermore, where CBCT imaging is used, per current guidelines, clinicians should obtain a report from an appropriately trained dentist with ‘level 2’ training or a radiologist.³³ Lastly, this case highlighted the importance of a multidisciplinary approach to provide patients with the best quality of care.