Comparison of two extraoral radiographic techniques used for nasopharyngeal airway space evaluation

Abstracts

OBJETIVO: esta pesquisa teve por objetivo comparar a utilização da radiografia cefalométrica de perfil e da radiografia de cavum na avaliação do espaço aéreo nasofaringeano. MÉTODOS: o estudo foi realizado em 2005 na cidade de Recife/PE, com um grupo de 36 crianças portadoras de respiração bucal, com idades variando de 5 a 12 anos. As crianças selecionadas foram divididas em 6 grupos e, em cada grupo, as tomadas radiográficas foram realizadas em um mesmo dia. A amostra constou de 72 radiografias, 36 cefalométricas de perfil e 36 de cavum. O laudo radiográfico foi baseado no método de Schulhof e, no final do laudo, foi emitido um Índice que representava uma síntese de todas as medidas avaliadas. RESULTADOS: os resultados foram comparados estatisticamente através do teste t de Student pareado, do teste qui-quadrado (X²), do coeficiente de correlação linear de Pearson e do índice Kappa. Apenas na porcentagem da via aérea foi encontrada diferença estatisticamente significativa (p = 0,006). Um alto grau de correlação foi verificado em todas as medidas avaliadas e o grau de concordância dos valores obtidos no Índice foi considerado bom. CONCLUSÃO: concluiu-se que a radiografia cefalométrica de perfil e a radiografia de cavum podem ser utilizadas para a análise do espaço aéreo nasofaringeano.

Adenoides; Nasofaringe; Radiografia

ORIGINAL ARTICLE

^ISpecialist in Orthodontics, FOP-UPE. MSc in Orthodontics, UERJ

^IIHead Professor of Orthodontics, FO/UERJ. MSc in Orthodontics, UFRJ

Contact address

ABSTRACT

OBJECTIVES: The goal of this research was to compare lateral cephalometric radiography and cavum radiography in nasopharyngeal airway space evaluation.

METHODS: The sample of this study consisted of 36 Brazilian mouth breathing children, no racial distinction, with ages ranging from 5 to 12. These children were selected in Recife/PE, Brazil (2005) and divided into 6 groups. In each group, the radiographs were taken on the same day. The sample was composed of 72 radiographs, 36 lateral cephalometric and 36 cavum.

RESULTS: The results were based on the Schulhof method and, at the end, an Index representing a summary of all measurements taken was calculated. Student paired t-test, chi-square, Pearson correlation and Kappa index scores were calculated to analyze the results. Only the values of the Airway Occupation Percentage were significantly different (p = 0.006) among the analyzed radiographs. A high degree of correlation was found for all measurements, including the Index values.

CONCLUSIONS: It can be concluded that, both the lateral cephalometric radiography and the cavum radiography can be used for nasopharyngeal airway space evaluation.

Keywords: Adenoids. Nasopharynx. Radiography.

INTRODUCTION

Adenoid hypertrophy is very common in children and usually occurs between 2 and 12 years of age, reducing or preventing nasal breathing.^11,14 This problem has been associated with several diseases, such as acute otitis media, secretory otitis media, increase of the middle turbinates, septal deviation, obstructive sleep apnea syndrome and chronic recurrent pharyngeal infections.^8,11 There is also an association between mouth breathing and craniofacial growth and development. Although it is not clearly defined whether it is the upper airway obstruction that leads to dentofacial deformities, or the existence of such deformities that leads to the airway deficiencies, the right diagnosis of the coexistence of both abnormalities is necessary, mainly to allow a good orthodontic treatment plan.

Due to the difficulty of establishing a definitive diagnosis only by clinical examinations, physicians and dentists use auxiliary exams to help the diagnosis of oral breathing. The additional routine examination for the child with a clinical diagnosis of adenoid hypertrophy is the radiographic examination.

Cavum radiograph is used by otorhinolaringologists, while orthodontists use lateral cephalometric radiography. Although they are distinct X-rays, they have the same purpose in nasopharyngeal airway space evaluation.

A mouth-breathing patient requires a multidisciplinary approach in their treatment, mainly involving otorhinolaringologists and orthodontists, so the comparison of these two radiographs would help to determine differences that may exist between the two radiographic techniques, considering the positive and negative factors, and probably avoiding the duplication of radiographs.

The purpose of the present study is to compare the lateral cephalometric radiographs, used by orthodontists, and cavum radiographs, used by otorhinolaringologists, taken from mouth-breathing patients in order to:

1. Statistically compare the data obtained for the percentage of the airway space occupied by the adenoid tissue and the linear measurements in the assessment of nasopharyngeal airway space.

2. Evaluate the correlation of these values in both radiographic techniques.

3. Establish whether only one of the radiographic techniques could satisfy both orthodontists and otorhinolaringologists.

MATERIAL AND METHODS

The anamnesis of 150 children, 67 girls and 83 boys was held by a single examiner, an orthodontist, in the Dental Clinic of Orthodontic Study Group (Ortogeo), in Recife/PE, Brazil. All children have Brazilian nationality, ages ranging from 5 to 12 years, without racial distinction, residents of the metropolitan area of Recife (PE).

The children were selected from three Dental Clinics: Dental Clinic of the Military Police of Pernambuco, Dental Clinic of Padre Antonio Manoel Hospital (Mirueira Hospital) and the Dental Clinic of Ortogeo.

Data regarding medical history were registered on a form specially designed for this study, including, besides personal identification data, questions related to the exclusion and inclusion of children in this study.

Were excluded patients according to the following criteria:

- Wearing orthodontic appliance;

- Taking any kind of medicine regularly;

- Had the adenoids removed;

- Had any congenital anomaly.

The inclusion criterion was the presence of mouth breathing habit. Initially, we considered to be mouth breathing those patients whose parents or guardians reported that their children were mouth breathers. Of a total of 150 children assessed, only 36 (21 boys and 15 girls) met the inclusion criteria established in this study.

The Ethical Committee of Pedro Ernesto University Hospital approved the study (nº 1082, CEP / HUPE) and also the Ethical Committee of Restauração Hospital (nº 0005.1.102.000-05).This study was registered in the SISNEP (National system of ethics in research).

An informed consent was obtained from parents or guardians, allowing children to participate in this study, according to Resolution No. 196, October 10, 1996, of the National Health Council responsible for regulating the principles governing research involving human beings.

A speech therapist examined all the patients. In the clinical examination the position of the lips, tongue and cheeks was observed, and speech-language tests were used to investigate proper speaking, breathing, chewing and swallowing. The results confirmed that 36 children were indeed mouth breathers.

In the next step, the radiographs of all the patients were taken on the same day using both extraoral radiographic techniques: Lateral cephalometric radiographs and cavum radiographs. To allow this, the patients were divided into six groups of six children each.

The lateral cephalometric radiographs were taken in the Radiology Clinic Radioface, Unit Derby in Recife (PE) and the standards for radiography were those described by Broadbent in April 1931.⁴

The cavum radiographs were taken in the Restauração Hospital and the standards for radiography were those described by Bontrager in March 2003.³

Demarcation of the cephalometric points and collection of the assessed measurements

All 72 radiographs were scanned in the Radioface Radiology Clinic by a single operator, a radiology technician, using the Epson Expression 1680 scanner. They were scanned with a 150 dpi resolution and processed in the CefX for Windows (CDT Company - Consultoria, Desenvolvimento, Treinamento em Informática Ltda., Cuiabá - MT, Brazil) cephalometric program. Using the same program, the cephalometric points were located in the 72 images, using the mouse, by another radiology specialist. Then, the same program generated the cephalometric and radiographic analysis of the adenoids.

The analysis used to evaluate the nasopharyngeal airway space was described by Schulhof.²² This analysis combines four cephalometric measurements used in the analysis of the nasopharyngeal region forming a system of four factors for assessing the nasopharyngeal airspace.

The first factor described by Handelman and Osborne,¹⁰ corresponds to the percentage of airway occupied by adenoid tissue in the nasopharynx area (Fig 1).

The second factor was described by Linder-Aronson and Henrikson¹⁵ and it is represented by the distance from the point AD1 to the posterior nasal spine (D-AD1:PNS) (Fig 2).

The third factor, also described by Linder-Aronson and Henrikson,¹⁵ represents the linear distance from the point AD2 to the posterior nasal spine (D-AD2:PNS) (Fig 3).

The fourth factor described by Schulhof²² is represented by the linear distance from point AD to a point of pterygoid vertical line 5 mm above the posterior nasal spine (D-PTV:AD) (Fig 4).

Radiograph report

After measuring lateral cephalometric radiographs and cavum radiographs, a computerized report of the nasopharyngeal airway analysis was printed.

According to the CefX program, the assessment of each measurement would be (Table 1):

• Large space: when the percentage of space occupied by adenoid was lower than the normal range in the first factor and the distance was greater than the normal range in the second, third and fourth factors.

• Normal: when the measurement found in the analysis was within normal limits.

• Localized obstruction: when the percentage of space occupied by adenoid was larger than the normal range in the first factor and the distance was shorter than the normal range in the second, third and fourth factors.

At the end of the computerized report an Index representing a summary of all the factors was emitted by the CefX. This Index ranged from 0 to 4:

• 0 and 1: No adenoid hypertrophy problems;

• 2: Possible adenoid hypertrophy problem;

• 3: Probable adenoid hypertrophy problem;

• 4: Adenoid hypertrophy problem.

A zero Index means that all examined measures were within normal limits; Index 1 means only one measure was out of the normal range; Index 2 means two measures were out of the normal range; Index 3 means three measures were outside the normal range and, finally, Index 4 means all four measures were out of the normal range.

Method errors

To calculate the intra-operator method error, all procedures for the nasopharyngeal airway space analysis were performed in ten lateral cephalometric radiographs and ten cavum radiographs. Starting with the scanning and ending with obtaining the radiographic measurements. These operations were repeated three times with a five-day interval between each essay. The results were statistically analyzed to verify the Kappa index score.

The result showed an excellent intra-operator agreement level. The Kappa index score of agreement for the assessment of intra-operator test was k = 0.89 (Table 2).

Statistical Analysis

In the statistical analysis of results, paired t-test and chi-square (X²) were performed. The computations were performed using the SPSS statistical software (Statistical Package for Social Sciences) version 14.0 for Windows operating system (SPSS Inc, Chicago, IL.).

This research adopted a 5% probability significance level (p <0.05).

RESULTS

Statistical evaluation of results

After obtaining the measurements, the minimum and maximum values, medians, standard deviations, and coefficient of variation of variables (percentage of airway space, D-AD1:PNS, D-AD2:PNS, D-PTV:AD) were calculated (Table 3).

When the paired t-test was applied, a statistically significant difference between the lateral cephalometric radiographs and cavum (p = 0.006) was found, on data obtained from the percentage of airway space analysis.

For the others variables (D-AD1:PNS, D-AD2: PNS and D-PTV:AD) the paired t-test showed no statistically significant difference between the two radiographic techniques and the values of p = 0.05, p = 0. 25 and p = 0.62, respectively.

The Pearson correlation coefficient was used with the objective of correlating the values obtained from lateral cephalometric radiographs and cavum radiographs.

In all variables, the results of the correlation coefficient showed that there was a high correlation (Table 4).

In the statistical analysis of the variable Index, chi-square (X²) was applied to compare the frequency distribution of this variable on lateral cephalometric and cavum radiographs. It was observed that there was no statistical significant difference in this variable in both x-rays in nasopharyngeal airway space analysis (p = 0.71).

The Kappa index score was used to check the degree of agreement of values obtained in the variable Index and the value obtained was good (k = 0.63), according to the values listed in Table 2.

Table 5 shows the percentages of the Index variable in the lateral cephalometric radiographs and cavum radiograph.

DISCUSSION

There are several causes to nasal obstruction: nasal septum deviation, tonsils and adenoids hypertrophy and increase of the middle turbinates.^8,19 However, there is a consensus in the literature that adenoid hypertrophy is the most important etiological factor that induces nasal obstruction.^9,17,19,24

The accuracy of radiographic methods for the assessment of nasopharyngeal airway space has been questioned, due to the static two-dimensional viewing generated by radiographs for the evaluation of a three-dimensional dynamic structure. Several studies have shown a significant correlation between the results obtained in the radiographic evaluation and those obtained in the clinical evaluation,²⁰ in the direct observation during surgery,⁶ in posterior rhinoscopy¹⁴ and nasal endoscopy.^12,18,25

The big difference between the lateral cephalometric radiography and the cavum radiograph is that the former uses the cephalostat to stabilize the patient's head. In the cavum radiography, the absence of the cephalostat during the procedure allows the patient to change the head position and requires more attention from the radiology technician.

According to Oliveira, Anselmo-Lima and Souza¹⁹ and Malkoc et al,¹⁶ a slight change in the patient's head position while the radiologic examination is performed could lead to important changes in the distances between the structures involved to assess the degree of obstruction of nasopharyngeal airway space.

In this research, two different radiographic techniques were used to evaluate the nasopharyngeal airway space, and not the size of the adenoids, because there is a consensus among authors that it is not the size of adenoids that should be evaluated, but rather the space in which it is inserted.^5,7,15,21,23

The Schulhof²² analysis was used in this study because it combines four cephalometric measurements, used in the nasopharyngeal region analysis, forming a system of four factors for assessing the nasopharyngeal airspace.

Regarding the data obtained through the evaluation of nasopharyngeal airway space, the averages of the D-AD1:PNS, D-AD2:PNS and D-PTV:AD were within the limits of nasal breathing according to Haldelman and Osborne;¹⁰ Linder-Aronson¹⁴ and Schullof.²² But our aim was not to verify the presence or absence of adenoid hypertrophy, but rather, to compare two radiographic methods used to measure the nasopharyngeal airway space.

The use of lateral radiographs in nasopharyngeal airway space evaluation is a practical and simple way to diagnose nasopharynx obstruction. Besides, it's a simple and low-cost available technique.^1,2

Since studies comparing the two techniques used in this research were not found in the literature, it's essential that new studies using the Schullof²² method or other methods of nasopharyngeal airway space measurement be compared with the results found in this research.

CONCLUSION

Based on the results of this research, it can be concluded that:

1. Only in the percentage of airway occupied by adenoid tissue there were significant differences between lateral cephalometric radiographs and cavum radiographs. However, in the other measures (linear variable D-AD1:PNS, D-AD2:PNS, D-PTV:AD) and the Index there were no statistically significant differences between the two radiographic techniques.

2. A high degree of correlation was found in all variables used to analyze the nasopharyngeal airway space in both radiographs, demonstrating equivalence between the two techniques.

3. For the nasopharyngeal airway space analysis, the lateral cephalometric radiograph or the cavum radiograph satisfy the needs of both orthodontists and otorhinolaryngologists.

ACKNOWLEDGMENTS

The authors would like to thank Dr. Tatiana de Aguiar Bulhões and the Research Centers Ortogeo, Restauração Hospital and Radioface that made possible the execution of this research.

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Comparison of two extraoral radiographic techniques used for nasopharyngeal airway space evaluation

Mariana de Aguiar Bulhões Galvão^I; Marco Antonio de Oliveira Almeida^II

Publication Dates

• Publication in this collection
  18 Aug 2010
• Date of issue
  Aug 2010

History

• Accepted
  Jan 2007
• Received
  Dec 2006