Differentiating OC from PC without access to imaging can be very difficult. As such, this study was undertaken with the aim to describe our experience with PC and OC, and to identify easily-accessible parameters that could be used to distinguish OC. The results show that the SNIPPED scoring system, which is comprised of sinusitis, NLR, platelet count, proptosis and duration of symptoms, was a reliable tool that could be used to predict OC.
Most cases of OC are caused by spread of infection from an adjacent infected sinus, especially ethmoid sinuses. Other much less common sources are spread from the globe (panophthalmitis), the eyelids, the lacrimal sac, infected teeth, and orbital foreign bodies. Finally, although rare, penetrating orbital trauma or skin infection of the face, dental infections, surgery involving ocular or dental regions may cause OC [6–8]. In a study from Turkey that evaluated 36 patients with orbital infections (32 PC and 4 OC) admitted in a 2-year period, the most common predisposing factor was sinusitis in 16 patients (12 PC and 4 OC), and all patients with OC had sinusitis as a predisposing factor [9]. A recently published study reported that 68% of pediatric PC and OC cases had respiratory tract infection or sinusitis [10]. In a retrospective cross-sectional study from a tertiary ophthalmology hospital including 93 pediatric and adult patients (39 OC and 54 PC), it was reported that sinusitis was the most common etiology in both groups and was significantly more frequent in the OC group [11]. In another retrospective study including 122 pediatric patients with 80.3% PC and 19.7% OC, sinusitis was reported to be associated with OC, whereas dental abscess and trauma were associated with PC [2]. In our study, sinusitis was more common in patients with OC- similar to previous studies. The inflammation around the eyes in PC occurs as a complication of paranasal sinusitis. The pathogenesis is attributable to the venous drainage of the eyelid and surrounding structures. OC occurs when the infection in the sinuses spread to the orbit through the neighborhood or venous spread [6, 12].
Among laboratory parameters, regression analysis only revealed that NLR and platelet count were associated with OC. Although inflammatory parameters are elevated in both PC and OC, the absolute levels of acute phase reactants may be helpful in clinical practice [12]. For instance, higher CRP levels were reported to be associated with post-septal disease in a recent study [10]. NLR is a parameter which is studied in bacterial infections such as neonatal sepsis, urinary tract infection and community acquired pneumonia [13–15]. A recent study which included 243 children with orbital infections, of whom 51 (20.6%) had OC, found that an NLR value of > 3.14 could differentiate OC from PC with a sensitivity of 75.5% and a specificity of 77.4% [16]. Our threshold of NLR (> 6.78) in OC patients seems a bit higher compared to the previous study; but these differences may be due to the well-known variations (based on measurement and devices) in NLR values.
Conjunctival cultures are frequently sterile in children with orbital infections. However, the most commonly identified organisms include Streptococcus spp., Staphylococcus spp., respiratory gram-negative organisms, and anaerobes [17]. In our study, the most common was Staphylococcus spp. (24%). Similarly, in a 10-year report including 94 patients (67 PC and 27 OC), the most common pathogen was S. aureus (local abscess, eye swab, and blood cultures) in both adult and pediatric patients. The authors also noted that S.aureus and S.pyogenes were the only agents identified in pediatric cases, while S.viridans, Pseudomonas spp., Escherichia coli, H.influenzae, Fusobacterium spp., Peptostreptococcus spp. demonstrated growth in the cultures of the adult group [18]. Another study that evaluated 213 pediatric cases with orbital infections reported that orbital cultures were performed in 54 (25%) children and the most common pathogen was S. aureus [19]. In a previous research including 94 children with OC (in which a pathogen was recovered in 31% of patients), the most commonly identified pathogen was S. anginosus group (15%), while S.aureus was identified in 9% of all patients [20]. In our study, only three of the cultures yielded S. anginosus group. Therefore, empirical treatment should cover all these pathogens in children with orbital infections [12].
There are a few systematic reviews that focus on the management of pediatric patients with periorbital cellulitis [21, 4]. In children with PC, IV antibiotics should be considered for infants and those with signs of serious systemic infection. Because the meninges are susceptible to inoculation in the infant age group, LP should be performed unless the clinical picture precludes meningitis [12]. In our study group, LP was performed in 9.9% of patients, but meningitis was not diagnosed in any subjects.
OC is treated with the administration of IV antibiotics after the patient is hospitalized. If the patient fails to respond to antibiotic treatment within 24 to 48 hours, it is reasonable to perform CT to look for an orbital abscess and/or plan for surgery [7, 21]. Orbital abscess development is associated with various factors, such as being older than 3 years old, having peripheral blood neutrophil count greater than 10.000/mm3, presence of periorbital edema and having received treatment with antibiotics previously [22]. All patients in our study group who needed surgery were above 3 years old and the most identified predisposing factor was sinusitis. The orbital surgery rate in the current study was 28.5% in the OC group and 2.6% overall. In a study which evaluated 175 pediatric cases (36 had OC), 27 patients had subperiosteal abscess and surgery was needed in 31 (1.7%) of all patients [10]. Another study found the rates of surgical intervention as follows: 29% overall (n = 93), 48.7% in the 39 patients with OC and 14.8% in the 54 patients with PC. The higher rates of surgery may be related to the inclusion of adult patients in this study [11]. It was stated that the proportion of patients requiring surgery increased with age in a study which evaluated 40 children treated for subperiosteal abscess [23]. It may be feasible to suggest that older children and those with sinusitis may benefit from being monitored more carefully about the development of subperiosteal abscess. In our study, surgical intervention was required in all but three of the patients with subperiosteal abscess. In these three patients, abscess diameter was small, fever and other symptoms resolved quickly, response was well to antibiotic treatment, and close monitoring was performed. Ultimately, control imaging studies were normal. Patients who underwent surgery did not attend follow-up visits which presents one of the limitations of this study.
The strength of this study is the large number of cases included over a 13-year period. Another strength is that, to our knowledge, this study is the first pediatric research that has found a novel scoring system to distinguish OC from PC. Previous studies show that imaging is required to differentiate between PC and OC; however, imaging is expensive and, more importantly, may not be available in resource-limited settings. The value of this scoring system comes from the fact that it drives its results from readily available and/or cheaply measured parameters. Although the ≥ 7-point cut-off has very good accuracy for the diagnosis of OC, the second cut-off point (≥ 12) was identified to describe a value that could be used for definite OC diagnosis in settings where imaging is not readily-available. In addition, this threshold can be used to quickly identify the severity of a patient when clinical suspicion is insufficient or imaging may be delayed.
There are some limitations to discuss. First, this is a retrospective study and carries all limitations associated with this design (ascertainment bias, selection bias). Second, although the number of patients included is respectable, all data is from only one tertiary center; thus, it may be feasible to perform prospective multicenter studies to better evaluate and confirm this scoring system by performing stratification based on various patient-related characteristics, including sex, age, race, and factors affecting the parameters used for scoring. Finally, it must be noted that we include a temporal parameter (duration of symptoms) in the scoring system. It is evident that judging the utility of this variable in patients who apply before 4 days of symptoms will require further studies. In relation, physicians must be aware of the fact that they must repeat score calculation daily until the 4th day when symptoms continue. However, to conclude, we believe that this score may be helpful to distinguish between PC and OC, since the early and promptly diagnosis and treatment of OC may prevent complications.