Surgical drainage of pediatric gas-containing orbital subperiosteal abscess

Abstract An orbital subperiosteal abscess (SPA) is a serious complication associated with acute rhinosinusitis (ARS). However, no established guidelines are available for the management of this condition in pediatric patients. We report a case of pediatric gas-containing ARS-induced SPA treated with surgical drainage. A 5-year-old boy was referred to our hospital for treatment of ARS-induced orbital complications. A computerized tomography (CT) revealed opacification of the sinuses and fluid collection with gas in the subperiosteal space of the orbital medial wall. Based on these findings, the patient was diagnosed with ARS-induced SPA and received an antibiotic therapy and thereafter underwent surgical drainage. Sinus CT performed at the 6-month follow-up confirmed regeneration of the orbital medial wall that was surgically resected. Currently, there is no report regarding as optimal surgery of pediatric SPA and postoperative condition. This is the first report of pediatric SPA in which regeneration of resected orbital wall was confirmed.


Introduction
Acute rhinosinusitis (ARS) is one of the most common pediatric infections worldwide.Some patients may develop orbital complications [1], and prompt diagnosis and appropriate management are important in such cases.Reportedly, the incidence of orbital complications in pediatric ARS was observed to be 6% [2].Subperiosteal abscesses (SPAs) account for approximately 30% of orbital complications associated with ARS [3].Refractoriness to 48-hour broad-spectrum antibiotic therapy necessitates surgical intervention.Surgery is particularly recommended in patients with orbital abscess or reduced visual acuity [4].However, specific guidelines are unavailable for the management of ARS-induced orbital complications in the pediatric population.No reports have detailed the method of drainage and postoperative condition of the orbital bones.We report a rare case of pediatric gas-containing SPA, which was successfully treated with endoscopic sinus surgery (ESS).

Case report
A 5-year-old boy with an unremarkable medical history presented to a primary care clinic with purulent nasal discharge together with a several-day history of right orbital swelling and was diagnosed with ARS.He received amoxicillin-clavulanate therapy for a few days; however, his symptoms persisted, and he was referred to our hospital for further management.The patient denied a history of trauma, ocular foreign bodies, or meningeal signs.Nasal endoscopy showed purulent nasal discharge in the right nasal cavity.Plain computed tomography (CT) of the sinuses revealed opacification of the right maxillary and ethmoid sinuses and fluid collection accompanied by gas in the subperiosteal space of the orbital medial wall, which compressed the globe and led to anterolateral deviation (Figure 1A).
Based on these findings, the patient was diagnosed with an orbital subperiosteal abscess associated with ARS.Laboratory test results showed a white blood cell count (WBC) of 12900/mm 3 and serum C-reactive protein (CRP) level of 8.66 mg/dL.Ophthalmologic evaluation confirmed inward and outward ocular dysmotility with diplopia of the right eye without visual impairment.Empiric intravenous antibiotic treatment was initiated using ceftriaxone (2 g/day) and clindamycin (720 mg/day).Cultures of nasal and eye discharge obtained before antibiotic administration yielded growth of Haemophilus parainfluenzae and Staphylococcus epidermidis, respectively.
Orbital swelling, ocular dysmotility, and purulent nasal discharge gradually improved following treatment initiation.Blood test results showed improvement on the 7th day of hospitalization (WBC 4200/mm 3 and serum CRP 0.30 mg/dL).
However, sinus CT performed on the same day revealed enlargement of the fluid collection in the subperiosteal space of the right orbit and destruction of the orbital medial wall (Figure 1B).Therefore, we performed ESS for abscess drainage on the 10th day of hospitalization in consultation with the patient and the family.
Intraoperatively, we performed resection of the uncinated process and the ethmoidal bulla, maxillary antrostomy, and right orbital decompression with removal of the orbital lamina (1 cm Â 1cm) (Figure 2A).The anterior ethmoidal artery was preserved (Figure 2A).We observed drainage of purulent discharge from the maxillary sinus and the subperiosteal space of the orbital lamina.The maxillary sinus mucosa was edematous (Figure 2B).Both aerobic and anaerobic cultures of pus obtained from the orbital  subperiosteal space yielded no growth, which was attributable to 10-day course of intravenous antibiotics administered to the patient.
Although the patient had fever for a few days postoperatively, orbital swelling gradually improved, and we observed no deterioration in blood test results.The patient was discharged on the 17th day of hospitalization.No recurrence was observed at the 6-month follow-up, and plain CT revealed regeneration of the right medial orbital wall (Figure 3).

Discussion
Orbital infections are associated with multifactorial etiologies, including septicemia, facial trauma, cutaneous infections, and rhinosinusitis.Among them, rhinosinusitis is most prevalent and accounts for approximately 70% of all cases of orbital infections [5].Anatomically, a close association exists between the orbit and the paranasal sinuses.Only a paper-thin bony plate separates the orbit from the ethmoid sinus.Moreover, the anterior and posterior ethmoidal foramen and the nerves and vessels that pass through the foramen serve as a route of transmission of infection from the ethmoidal sinuses to the orbit [6].
A few studies have reported bacteria associated with ARS-induced orbital infections.Hwang et al. [7] reported that Streptococcus viridans was most frequently isolated in pediatric cases of complicated ARS.Oxford and McClay [8] reported that Streptococcus milleri was isolated in 7 of 23 pediatric patients with ARS-associated SPA.Devrim et al. [9] reported that Staphylococcus aureus was the most commonly isolated organism (41.9%), followed by coagulase-negative Staphylococcus (25.8%), and Haemophilus influenzae type B (6%) in patients with orbital cellulitis.Although bacterial culture test results are important to guide the choice of antibiotics, approximately 30% of cultures tend to yield no growth in complicated pediatric ARS [10], which is perhaps attributable to the fact that nearly all patients receive oral antibiotic treatment before they visit a higher level of specialized medical care.
Haemophilus parainfluenzae and Staphylococcus epidermidis were isolated from the nasal and eye discharge, respectively, in our patient.These species are occasionally isolated from the nasal discharge of patients with ARS [11].However, sinus CT at the time of the patient's first visit to our hospital revealed a gas-containing area in the subperiosteal fluid, which suggested the possibility of anaerobic infection [12].Although intra-orbital gas may have entered through the nasal cavity, we considered the presence of gasproducing bacteria in the orbit because the initial sinus CT revealed no destruction of the orbital wall.However, no anaerobic bacteria were isolated from the orbital subperiosteal pus obtained intraoperatively, probably due to preoperative antibiotic treatment.Additionally, there are many bacterial species that cannot be detected under normal culture conditions.DNA sequencing may be useful when reliable identification of the causative organism is required [11].To our knowledge, only one previous study has reported a case of pediatric gas-containing orbital cellulitis followed by ARS [13]; no anaerobic bacteria were isolated, and only Streptococcus pneumoniae was detected in the nasal discharge.Reportedly, anaerobes are isolated in most pediatric rhinosinusitis cases [14].Therefore, clinicians should be mindful of the activity of anaerobic bacteria in cases of complicated ARS.
Currently, no definitive guidelines are established with regard to the indications for and timing of initiation of surgery in cases of pediatric SPA.Although some studies have shown that surgical drainage is not always necessary in pediatric cases of ARS-induced SPA, the percentage of surgically-treated cases varies widely between 10% and 90% [15].Several studies attempted to establish surgical indications for pediatric SPA.Sciarretta et al. [16] reported nine cases of pediatric rhinogenic SPA treated with surgical drainage.In the report, surgery was performed on patients who did not improve despite 48 h of antibiotic administration.Nation et al. [17] recommended surgical drainage in cases of pediatric SPA with an abscess volume of !500 mm 3 based on their review of 48 cases of pediatric SPA.Quintanilla-Dieck et al. [18] reported that presence of 3.85 mm or more of proptosis was predictive value for surgical intervention.Our case was filled with an abscess volume of !500 mm 3 and proptosis !3.85 mm.
In the present case, surgical drainage was performed on the 10th day of hospitalization, which is later than the time of surgery reported by the previous study [17].This time point was chosen because of the gradual improvement in blood test results and orbital swelling and unexpected worsening in CT findings observed on the 7th day of hospitalization.Surgical drainage after appropriate antibacterial treatment may be an effective therapeutic approach depending on the clinical situation.
There is no report regarding as optimal surgery of pediatric SPA, albeit some studies [16][17][18] have attempted to establish surgical indication criteria.The impacts of ESS on maxillofacial development in pediatric patients is concerning.Reportedly, no significant effect was observed over 10-year follow-up after ESS in pediatric patients [19].Surgeons are often reluctant to resect orbital bones and aim for minimal procedure in pediatric cases.In our case, sinus CT revealed regeneration of the medial orbital wall that was resected during drainage surgery.This result suggests that excision of a small area of the orbital wall in pediatric cases of SPA may be acceptable.

Conclusion
We reported a pediatric case of ARS-induced gas-containing SPA that improved after drainage surgery following an appropriate antibiotic treatment, with subsequent regeneration of orbital wall.This report adds to the current knowledge base by suggesting that excision of a small area of the orbital wall in pediatric cases of SPA may be acceptable.This report will contribute to considering the acceptable range of orbital wall resection in pediatric cases of SPA.Optimal treatment of pediatric SPA is not conclusively established; therefore, careful follow-up and accumulation of a greater number of cases are necessary in the future.

Ethical approval
Written informed consent was obtained from the patients for the publication of any potentially identifiable images or data included in this article.

Figure 1 .
Figure 1.(A) Sinus CT images (coronal and axial views) obtained at the time of admission.Fluid collection with gas within is observed in the subperiosteal space of the right orbital medial wall (arrow).(B) Sinus CT images (coronal and axial views) obtained on the 7th day of hospitalization showing destruction of the right orbital medial wall (arrow head).CT: computed tomography

Figure 2 .
Figure 2. Intraoperative endoscopic findings of the right middle meatus.The orbital lamina is resected and the subperiosteal abscess is drained.The AEA is preserved.AEA: anterior ethmoidal artery.

Figure 3 .
Figure 3. Sinus CT images (coronal and axial views) obtained 6 months after discharge.Regeneration of the right medial orbital wall is clearly visualized (arrow).CT: computed tomography.