Among the pediatric population, nasal bone fractures are the most common type of facial bone injury,1–3 occurring commonly in sports and traffic accidents, accidental falls, and so on. Accurate diagnosis and prompt nasal bone repositioning is crucial for optimal results.4 Although nasal bone fractures are also common in the adult population, diagnosis of pediatric patients is sometimes more difficult because of the relative underdevelopment of nasal structures in children.3 Swelling of nasal soft tissue following facial trauma can easily mask deformity resulting from nasal bone damage incurred in an accident. The swelling may require days to subside. Noncooperation of the patient with clinical examination can also present difficulties in diagnosis5; hence the use of an imaging modality is often indispensable to timely diagnosis and intervention.
Among the available modalities, the nasal bone x-ray is common and easy to perform. However, diagnosis by x-ray is not considered satisfactory.6–8 Computed tomography (CT) imaging is a common alternative, and can easily detect fracture lines and degree of deformity.9 However, at least for the pediatric population, use of CT imaging should be limited because of concerns about radiation exposure and sedation.
Ultrasonography (US) was recently reported as a reliable modality for diagnosing nasal bone fractures. Some studies have reported that US is equal, or even superior, to CT in terms of accuracy.10–13 However, as these studies did not focus on specific age groups, the clinical utility of US specifically for the diagnosis of pediatric nasal bone fracture remains unclear. Moreover, the aim of the studies was only to compare the 2 modalities, and did not address the question, “Can US serve as a substitute for CT in the diagnosis of pediatric nasal bone injury?” The aim of the present prospective cohort study, therefore, was twofold: first, to investigate the utility of US in the diagnosis of pediatric nasal bone fractures, and second, to assess the validity of our protocol for managing pediatric nasal bone fractures.
PATIENTS AND METHODS
This prospective cohort study was conducted in accordance with the Declaration of Helsinki, and was approved by the Institutional Review Board of Tokyo Metropolitan Children's Medical Center (TMCMC).
Tokyo Metropolitan Children's Medical Center is a pediatric hospital located in Tokyo, and receives about 38,000 patients per year at Emergency Department (ED). Emergency Department is staffed by full-time physicians, and general pediatric registrars are always supervised by emergency physicians when treating trauma patients.
Among the patients who presented at the ED of TMCMC with facial trauma between July 1, 2014 and June 30, 2015, those with any clinical symptoms suggesting nasal bone fracture (eg, tenderness, swelling, wound or deformity of the nose) but without any other apparent facial bone fractures, were enrolled into the study.
Those who had any of the conditions listed below were excluded from the study:
1. Facial trauma possibly involving other parts of the craniofacial region besides the nose. If more complex craniofacial trauma was suspected, the best course of treatment for each individual was determined by the ED doctors and administered.
2. Nasal bone fracture patients already diagnosed using some imaging modality at another hospital/clinic and referred to our hospital.
3. Patients with a history of nasal bone fracture before this visit.
Patients were processed using the nasal bone fracture algorithm developed at TMCMC (Fuchu-Kids algorithm; Fig. 1), according to which individuals with any symptoms suggesting nasal bone fracture are further examined using US (SonoSite M-Turbo manufactured by FUJIFILM SonoSite Inc, Tokyo, Japan).
Before proceeding with patient enrolment, a US workshop was carried out in the ED as a refresher course in diagnostic skills for emergency physicians. Nasal bone US was carried out by emergency physicians or general pediatric registrars. General pediatric registrars who treated patients with a suspected nasal bone fracture were generally supervised by emergency physicians.
1. If US imaging discloses any indication of possible nasal bone fracture such as irregularities in bone structure, asymmetry, or depression of the nasal bone, CT imaging was carried out to confirm the findings and if necessary further investigate the extent of deformity. All those who underwent CT imaging were referred to the department of plastic and reconstructive surgery (PRS) to confirm the final diagnosis, and physicians discussed treatment options with the patients and their family.
2. If the US examination at the patient's first visit was negative for nasal bone fracture, the patient was asked to visit the ED again 4 to 8 days later. If suspicious symptoms still remained at the second visit, a second round of US imaging was carried out.
3. If the second US was positive, the patient was managed according to the protocol mentioned earlier.
4. If both US were negative, the patient was asked to appear for the last consultation at the PRS outpatient clinic for a final follow-up examination 6 to 12 weeks later. For those who were absent or unable to appear, a telephone interview was carried out to determine whether any of the initially observed symptoms of nasal bone trauma persisted.
Patients included in the study were categorized into 4 groups as described below, and the outcome of the study was assessed.
1. True negative: The patients with a negative result for both US, who did not receive a final diagnosis of nasal bone fracture, were placed in this group. Although some patients were interviewed by telephone for final counseling instead of undergoing examination at the PRS outpatient clinic, if they presented no clinical symptoms they were regarded as negative for nasal bone fracture.
2. False negative: Patients who received a final diagnosis of nasal bone injury by PRS examination and CT despite negative results for both US were placed into this group.
3. True positive: Patients whose US were both positive for nasal bone injury, and who received a final diagnosis confirming this result, were placed in this group. This group included patients with a negative first US and a positive second US. To investigate the diagnostic power of the single US examination, these patients were later examined more closely.
4. False positive: Patients with positive US findings but with subsequent CT imaging and PRS examination revealing no nasal bone fracture were placed in this group.
Eighty-one patients were enrolled in this study during the 1-year study period. Among these, 63 patients were processed to the full extent of the protocol and were subsequently further examined. Reasons for exclusion included absence from the second visit, or unavailability for a telephone interview, and so on.
Although the second ED visit took place 9 days after first visit in 2 patients and 3 days after first visit in 1 patient, all these patients were considered to be candidates for this study and were further investigated.
Forty-three patients were male and 20 were female. Age at the first visit ranged from 1 year 0 month to 14 years 1 month (average: 6 years 8 months).
Thirty-six patients were placed in the true negative group. Two patients were placed in the false negative group. Twenty-two patients were placed in the true positive group, but 4 of these were diagnosed by repeated US examination at their second ED visit. Three patients were placed in the false positive group (Fig. 2). Therefore, the diagnostic power of the Fuchu-Kids algorithm compared to a decision based on comprehensive clinical examination and CT was assessed as follows: sensitivity = 91.7%, specificity = 92.3%, positive predictive value (PPV) = 88%, and negative predictive value (NPV) = 94.7%.
However, when the performance of US was assessed as a single examination rather than as 2 sequential examinations in the context of the algorithm, its sensitivity, specificity, PPV, and NPV were 75%, 92.3%, 85.7%, and 85.7%, respectively.
Using the Fuchu-Kids algorithm resulted in the successful diagnosis of the majority of patients with nasal bone fractures. The majority of patients with facial trauma without nasal bone fractures were also screened out successfully. Repeated US imaging is considered to be effective when clinical symptoms persist despite a negative result for the first US imaging.
Diagnosing pediatric nasal fractures is sometimes very difficult when swelling and hematomas around a nonprominent nose masks the deformity. Patient noncompliance with examination makes the diagnosis even more difficult. Although as a rule careful physical examination is the ideal method of diagnosing nasal bone fractures, this is often not feasible for reasons such as those given above. Therefore, an appropriate imaging modality is crucial to overcoming these difficulties.
A conventional nasal bone radiograph is a quick and easy way of obtaining nasal bone images, and used to be a common imaging modality. However, the diagnostic value of a plain radiograph is now regarded as low. Nigam et al6 reported a poor correlation between the radiological findings and external deformities and concluded that a routine radiograph is unnecessary. Logan et al7 also reported in their prospective study that decisions regarding treatment of nasal trauma are based on clinical findings and nasal bone radiographs should be abandoned.
Computed tomography has also been a popular imaging modality for the diagnosis of nasal bone fracture, and has demonstrated its utility not only in visualizing the severity of the nasal bone deformities but also in detecting deep lesions. Hwang et al9 clarified nasal bone fractures in their 6-year study of 503 patients and concluded that CT was necessary for diagnosing nasal bone fractures and for helping to determine the best treatment options.
However, CT use raises 2 major concerns, especially among the pediatric population. One is irradiation. Healthcare providers are increasingly conscious of the risks of cataracts or cancer resulting from irradiation. Consequently, many studies proposing a more appropriate use of CT14,15 or suggesting viable alternatives in various clinical settings have been published.16–18 We should be aware of such dangers related to CT irradiation and refrain from excessive use of this modality.
The other concern regard appropriate sedation during CT. Langhan et al19 reported that hypoventilation, a common occurrence during sedation of pediatric emergency patients, can be difficult to detect by current monitoring methods. Although the latest forms of CT require less time to administer, given that procedural sedation carries the risk of serious adverse events, use of CT, and other imaging techniques requiring procedural sedation should be carried out in an evidence based, structured approach.20
Recently, US has been recognized as a reliable modality for diagnosing nasal bone fractures due to its high sensitivity and specificity.9–12,21–23 However, most reports have not targeted specific age groups like the pediatric population. As previously mentioned, pediatric patients have different anatomical and behavioral characteristics from the adult population that render its use problematic at times, and the question of the efficacy of US in daily pediatric ED practice has not been addressed. On the other hand, our clinical protocol using US demonstrated high sensitivity and specificity even for the pediatric patient group. Our Fuchu-Kids protocol proved to be a useful algorithm for screening for pediatric nasal bone fractures.
The biggest difference of our study from previous reports is that our protocol requires a maximum of 2 US examinations. If all suspicious patients had been diagnosed by a single examination, the accuracy of our diagnosis would have shown a sensitivity of 75%, a specificity of 92.3%, a PPV of 85.7%, and an NPV of 85.7%, which are not satisfactory for an imaging examination in ED practice. The shortcomings reflected by these results may be due to the characteristics of pediatric patients mentioned earlier. In particular, lack of cooperation by the patient during examination can result in minor fractures being overlooked. Hong et al reported that US was able to visualize “all” 26 pediatric nasal fractures,23 thus demonstrating a much higher diagnostic power for US than we were able to show. However, because their study did not mention patients without nasal fractures, the reason for the apparent difference between their findings and ours could not be ascertained. Our findings at any rate indicate that repeated US examination at the second visit for patients with protracted symptoms is a useful diagnostic feature of the protocol.
Two patients in whom no nasal bone fracture could be found even after 2 US examinations were examined further by a retrospective review of their chart. As far as we could be determined by the chart review, these 2 patients presented nasal bone trauma and clinical deformities highly suggestive of fractures; hence we would like to emphasize the importance of a clinical examination. Treatment indication should be decided on the basis of the clinical symptoms, not on the fracture lines visualized by the imaging modalities. Although US imaging is considered a very powerful tool for diagnosing nasal bone fractures, expectations of its efficacy need to be tempered when this modality is used with pediatric patients.
Limitations of this study include as follows.
Differences Between Examiners
Our ED is managed by many doctors including general pediatric registrars. Although attending emergency physicians generally supervise these registrars when carrying out an US, the quality of diagnosis based on the US findings may have varied among the examiners.
Limitation of Follow-Up Rate
Another limitation is in the follow-up ratio (63/81; 77.8%). Generally, because those without nasal symptoms tend to forego a second visit, the omission of these patients from the study did not decrease the validity of the present protocol. However, it was difficult to conclude how the omitted patients could have influenced the results.
Qualification of the Final Check-Up by Telephone Interview
To make the final diagnosis, we used a telephone interview if the patients were not available for the last appointment. Although we conducted a detailed interview to ascertain the extent of deformity of the patient's nose, there still remains the possibility that the true negative group might have contained patients with a very minor nasal bone fracture.
The authors express heartfelt gratitude to all the medical staff of the Department of Emergency Medicine and the Department of General Pediatrics, who kindly cooperated with us in this study. The authors also wish to acknowledge Mr James R. Valera for his help in editing this manuscript.
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