Nasopharyngeal cephalometrics

dental radiology Editor:

LINCOLN R. MANSON-HING, D.M.S., M.S. American Academy of Dental Radiology School of Dentistry, University of Alabama 1919 Seventh Avenue South Birmingham, Alabama 35233

Nasopharyngeal cephalometrics Morris N. Poole, D.D.S., M.S., Gary A. Engel, B.A., M.S., and Spiro J. Chaconas, D.D.S., M.S., Encino, Calif. FOUNDATION

FOR ORTHODONTIC

RESEARCH

A sample of 104 patients, males and females between the ages of 6 and 16 years, was studied. The sample included patients with clinically diagnosed nasopharyngeal obstruction, patients with no obstruction, and a random sample of patients for whom the presence or absence of obstruction was not known. More than 200 cephalometric measurements were used in an attempt to identify differences between the first two groups. Statistical t tests revealed four variables, all primarily related to adenoid size and nasopharyngeal dimensions, for which the mean values of the two groups were significantly different. Cephalometric norms for these four measurements were established, using the random sample patients, and these norms were calculated for various ages and both sexes. A method of identifying the degree of obstruction was then formulated on the basis of the four significant measurements. Preliminary results indicate that this method is highly correlated with observed clinical results.

ccording to the international medical health litA erature,’ the tonsil- and adenoidectomy is the most frequently performed surgical procedure. Tonsillo-adenoidectomies(T and A) are performed for the following classic indications*: (1) chronic nasopharyngeal obstruction, (2) pulmonary hypertension, (3) severe and chronic tonsillitis, (4) peritonsillar abscess,(5) otitis media, (6) rhinitis, and (7) sinusitis. Surgical proceduresand antibiotics have reduced the surgical morbidity rate to 0.001-0.0001. The 1968 study by Evans3indicated that 85 percent of all physicians believed that T and A’s were justified when at least some of the classic indications described above were observed. A review of the otorhinolaryngologic literature presentsfew articles concerning the management of present adenotonsillectomy patients; however, the orthodontic literature presentsnumerous references on the growth of lymphatic tissue within the nasopharynx.a The objective of this article is to present a system which will quantify and qualify the status of pediatric patients being considered for T and A. Chronic nasopharyngeal “inflammation” or ob266

struction is far too often used as the subjective criterion to justify the performanceof a T and A. However, the incidence of craniofacial osseous anomalies (for example, submucouscleft palate) cannot be determined without quantifying radiologic information (profiles). Analysis of the nasopharyngealcephalometric profile will reduce the probability and incidence of the danger of postoperative velopharyngeal incompetence in T and A surgery. It hasbeenreportedthat occurrenceof temporary hypemasality following T and A operations is at least 7.2 percent5 In instances where the nasopharyngeal cephalometric analysis indicates that the proportion of lymphatic tissue is excessiveto the point where it occludes the nasopharyngealrespiration system, cinefluorographic4 and videotape radiologic studies of the head and neck are recommended. The dental literature refersto “mouth-breathing problems” asan indication for T and A. 1s,20 However, we do not consider mouth breathing a pathologic process. The nasopharyngeal cephalometric profile presents areasof anatomic displacementor distortion which are not easily recognized during the routine subjective 0030-422Q/80/030266+06$00.60/0

0 1980 The C. V. Mosby Co.

Volume 49 Number 3

clinical head and neck evaluation. A very few health centers coordinate dental/medical (pedodontic, orthodontic , pediatric, allergy, otorhinolaryngologic) information via routine radiologic cephalometric evaluation. The results of this analysis should be used to complement the pathologic profile (chronic tonsillitis) so that multidisciplinary clinicians can managethe patient through a clinical growth period (9 to 13 years). REVIEW OF THE LITERATURE

The nasopharyngeal tonsil, pharyngeal tonsil, or adenoid is a component of a ring of several lymphoid tissue massesknown as Waldeyer’s ring. The remaining components include the palatine or faucial tonsils, the lingual tonsils, and a scatteredcollection of lymphoid follicles within the mucous membranes of the pharyngeal wall .6 Although its function is not completely understood, the adenoid has been studied extensively in order to clarify its role in relation to the development of the nasopharynx and its accompanying airway. In 1930, Scammon’ pointed out that lymphatic tissue, such as that of intestingal lymphoid massesand thymus, showsrapid growth in infancy and early childhood and continues to grow, though at a slower rate, until puberty, with a gradual decline thereafter. A subsequentstudy of adenoid configuration in the midsagittal plane by Subtelny and Koepp-Bakera has confirmed that adenoids follow Scammon’s lymphatic cycle. The study indicated that the adenoidsare apparent on x-ray at 6 months of age and attain their maximum massbetween the agesof 9 and 15 years. In a study by Pruzansky and Handelman,s the relative size of the adenoid was compared to the area occupied in the nasopharynx. It was found that adenoids judged to be large relative to their nasopharyngeal housing are most frequently observedbetween the ages of 4 and 6 years and becomeless frequently observedin the older groups. It has also been found that a number of seemingly unrelated medical problems can be the result of an imbalance between the sizes of the adenoids and the nasopharynx. Cases of hypoventilation and car pulmonale due to chronic upper airway obstruction have been reported in the literature by Menashe, Farrehi, and Miller.‘O When such cases were treated by tonsillectomy and adenoidectomy, dramatic improvement was shown in respiration, cyanosis disappeared,right ventricular hypertrophy receded, and normal activity was resumed. Levy and associates” reported a case of hypertrophied adenoids causing pulmonary hypertension and severecongestive heart failure. An adenoidectomy

Nasopharyngeal

cephalometrics

267

was performed becauseit was believed that this alone might be sufficient to relieve the obstructed airway. Afterward the patient progressively improved. Balanced against the medical problems that occur with enlarged adenoids are the possible detrimental effects to the human body caused by the removal of adenoid tissue. One problem that may be encountered is a decrease in the body’s immunity to illness and disease. The production of immunoglobulins by the body’s lymphoid tissue, including the adenoids, has been found to be important in preserving immunity. In fact, according to Steele and colleagues,” the lymphoid follicles in the spleen and in the tonsillar tissue, as well as the other lymphatic tissues in the body, are the main sourcesof immunoglobulins . Lateral cephalometric roentgenograms have been used to study the growth of the nasopharynx and the adenoid tissue.16Since both soft and hard tissue can be viewed on such roentgenogram, the soft tissue of the nasopharynx can be easily related to bony landmarksof the face and cranium. The frontal or posteroanterior radiographic view has also been used occasionally in the study of the bony airway, especially in order to gain a three-dimensional perspective of the nasal and pharyngeal airway. Linder-Aronson12* I3 of Sweden, in a study of the effect of adenoidson airflow, facial skeleton, and dentition , used forty-five linear, angular, and twodimensional measurementsfrom lateral cephalometric and posteroanterior radiographs to classify skeletal changes in mouth breathers. He stated that, according to his measurements,the skeletal variable of greatest importance for mouth breathing appearsto be the size of the nasopharynx. A nasopharyngealarea was derived mathematically by Handelman and Osbome,6 using nasopharyngeal depth, nasopharyngeal height, and the angle of the basion-nasion line to the palatal plane (Fig. 3). With these measurements, the relative areas occupied by airway and soft tissue were calculated for a number of cases. A measurementof nasopharyngeal depth to determine adenoid blockage of the nasopharynx was advanced by Ricketts.I*, ” He recommendeda measurement from pterygoid vertical (PTV) to the adenoid tissue, 5 mm. superior to the palatai plane (ANS-PNS), which he found to be an excellent discriminator between mouth breathers and non-mouth breathers. In his masters’ thesis, Bushey15studied the alterations in anatomic relations accompanying the change from oral to nasal breathing, and vice versa. He used over a dozen lateral cephalometric measurementsto

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Poole, Engel, and Chuconas

Fig. 1. Computertracingof a hypotheticalpatient,10yearsof

age,with all normalvalues,usingthe RockyMountainData Systemscomputerized200-pointsystem. measure these changes in bony landmarks as well as soft-tissue changes. The nasopharyngeal cephalometric procedures described can be usedto create a systemwhich will aid in determining the need for adenoidectomy. This article deals with the development of a nasopharyngeal cephalometric analysis system. METHODS AND MATERIALS

From a group of thirty patients who were examined, twenty-two were clinically diagnosedby ear, nose, and throat specialists and/or orthodontists as having nasopharyngeal obstructions. This group comprised fourteen girls and eight boys, ranging in agesfrom 7 years 10 months to 14 years 8 months. The remaining eight patients consistedof four girls and four boys ranging in age from 6 years 1 month to 9 years 11 months. This group had been clinically diagnosed as having no nasopharyngealobstruction. Lateral and frontal cephalometric tracings were made from head films taken of each of these patients. These tracings were used in evaluating and measuring softand hard-tissue relationships. The tracings were analyzed by a computerizedcephalometric system.l8 Fig. 1 shows a computer tracing of a hypothetical patient with all normal values. A composite computer tracing for the “obstruction” group is shown in Fig. 2. More than 200 measurementswere used to analyze

Oral Sung. March, 1980

Fig. 2. Compositecomputertracingfor the mouth-breathing sample,usingthe RMDS200-p&t system. the frontal and lateral tracings. These measurements included not only standard cephalometric lateral and frontal measurements18but also many measurements used in previous studiess,I23l5 or those hypothesizedto be useful in measuring adenoid development. Statistical t tests were used to determine the effectiveness of each measurement as a discriminator between the obstructed and unobstructed cases. Statistical discriminant function analyses were employed subsequentto the statistical t tests in order to find a method by which the values of several variables could be used simultaneously to determine whether obstruction existed. Normal values and standarddeviations of the four most highly significant variables were then calculated from a random sample consisting of seventy-four patients of both sexesbetween the agesof 6 and 16. The data were then reviewed and the results were evaluated. RESULTS AND DISCUSSION

The initial statistical t tests(Table I) of the 200 measurements made on each of thirty persons revealed eight statistically significant measurements ((.u= 0.05), and all primarily related to adenoid hypertrophy and/or nasopharyngealdimensions. These eight measurementsare illustrated in Fig. 3 and are described as follows: 1. Adenoid percentage: Percentageof nasopharynx occupied by adenoid tissue (shown in Fig. 3 as the ratio of striped area to trapezoid area). This measurementis

Nasopharyngeal cephalometrics

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NA E AsNS

299

NAsm

!i%%R

ATLAS

EEF NASAL sP’rE PNS POSTERIOR NASAL SPINE

Fig. 3. Cephalometric

measurements of the nasopharyngeal area.

Table I. Results of statistical t tests (two sided)

x Airway percentage D-AD1:PNS (mm) DAD2:PNS (mm) D-PTV:AD (mm.) b (degrees) 4 WF=S) Angle 6 (degrees) PosteriorHeight (mm.)

35.16 14.82

11.73 5.08 56.41 39.88 29.95

49.18

I

x,

Sl

49.28 22.90 16.39 11.83 61.50 44.29 23.87 45.32

10.68 3.84 2.85 3.32 5.84 4.93 3.57 6.67

I

SZ 1.57 3.06 2.67 4.31 3.28 3.67

1.73 3.23

t

df

4.06 5.10 4.26 4.17 2.99 2.68 -2.28 -2.10

29 29 29 29 29 29 29 29

Sign& level

.Ool .OOl .ool

,001 .Ol .02 .05 .05

g, = Sample mean of mouth breathers. Xs = Sample mean of non-mouth breathers. S, = Standarddeviation of first population mouth breathers. S2 = Standard deviation of secondpopulation non-mouthbreathers. -

x, - xz (N, - 1)s: + (N, -1)s: sp = S&m* N,+N,-- 2 J N, = Sample size of first population. N, = Sample size of secondpopulation. N, =N, + Nf. df (degreesof freedom) = N, - 1. t=

a modification of Handelman’s and Osborne’s6 nasopharyngeal area measuredin the study of adenoid development as published in July, 1976. 2. D-AD1 : PNS: Distance from PNS to the neatest adenoid tissue measuredalong a line through PNS perpendicular to S-BA (Fig. 3). 3. D-AD2 : PNS: Distance from PNS to the nearest adenoid tissue measuredalong a line through PNS perpendicular to S-BA (Fig. 3). Linder-Aronson13 used these two measurementsin his study of anteroposterior nasopharyngealdimensions of “mouth breathers” and “nose breathers.’ ’ 4. D-PW:AD: Distance to the nearest adenoid tis-

sue from a point on PTV 5 mm. superior to PNS (Fig. 3). Ricketts14,I7 used this measurementin his analysis of the nasopharyngeal “airway. ” 5. Posterior height: The length of the line S-AA (Sella-anterior atlas). 6. 8: The angle formed by the interaction of the lines PNS-ANS and BA-NA (Fig. 3). 7. D 1: The angle AA-S-PNS (Fig. 3). 8. D 2: The angle BA-S-PM (pig. 3). The last four measurementswere found in research done by Bushey15on alterations in certain anatomic relations accompanying the change from oral to nasal breathing.

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Poole, Engel, and Chaconas

Oral Surg. March, 1980

Table II. Norms for airway measurements Male

Female

I Measurement

I

I

6yr.

16 yr.

6 yr.

16 yr.

x

50.55

63.96

15.85

12.80

50.99 13.49

62.68

s

D-ADl:PNS

x

20.66 5.50

14.74

D-AD2:PNS

51 S x S

26.48 5.45 22.44 4.26

Airway percent

S

D-PTV:AD

15.89 3.53 7.07 3.84

14.59 6.10

16.09

5.69

26.32 4.28

14.93

21.78

3.52 7.02 3.87

14.56

4.67 4.70

‘il = Mean. S = Standarddeviation.

Table III. Classifications: Degree of adenoid problem No. of measurements more than one standard deviation below norm

o-1 2 3 4

I

Classification

No adenoid problem Possible adenoid problem Probable adenoid problem Definite adenoid problem

Of these eight measurements,four (airway percentage, D-AD1 : PNS, D-AD2 : PNS, and D-PTV : AD) were found by statistical t tests to be more highly significant than the others. The level of significance of thesefour measurementswith respectto the t test was at least 0.001 in all cases.Discriminant function analyses performed on combinations of these eight variables further substantiated the value of the four measurements. Next, norms were calculated for each of the four most significant variables from the random sample of seventy-four cases. Norms and standard deviations at the agesof 6 and 16 for both sexesare shown in Table II. Norms and standard deviations for any age in between can be estimated by linear interpolation. Great variation can be seenin the mean values with respectto age, but little difference is noted between sexes. In comparing measurementsof the original sampleof twenty-two persons with the norms, it was noted that no single measurementconsistently reflected nasopharyngeal blockage. In some cases, one or two measurementswould be more than one standard deviation below normal, while in other casesthree or all of the four measurementswould be significantly below normal. In still other cases, none of the variables were significantly below the norm. On the basis of information obtained from the previously mentioned statistical tests, a procedure was developed to determine when an adenoid problem exists. The technique is as follows: For each case to be classified, the four variables

(adenoid percentage,D-AD1 : PNS, D-AD2: PNS, and D-PTV:AD) are measuredand comparedto the norms derived from the sampledata and listed in Table II. For each individual, the number of measurementsfalling more than one standard deviation below the norm is counted, and the classification schemeusedis shown in Table III. The exactness of this scheme was then tested by classifying patients with known adenoid problems, as well as patients with no adenoid problems. By use of the Bayesian statistics, it was shown that fewer than 5 percent of the patients with no adenoidal obstruction will be classified incorrectly as having possible adenoid problems, and fewer than 0.5 percent will be classified as having probable or certain adenoid problems. In addition, the severity of the adenoid problem can be estimated by adding the standard deviations below the norm of all four measurements.Patients with a summation value of less than -6 clinical deviations are. thought to have severe adenoid problems, while those with adenoid problems whose summation is more than -6 are regarded as having moderateproblems. The determination of the needfor adenoidectomyhas heretofore beenprimarily a subjective clinical decision. Various schools of thought range from “When in doubt, take it out” to “It’s a sin not to leave them in.” A continuous searchfor the answer of when to remove or leave tonsils and adenoidshas often been a controversial one. For this reason, it is hoped that the method presentedhere will begin to clarify the question. It is felt that, when the nasophuryngeal cephalometric analysis is used to diagnose adenoid problems, the possibility of postoperative complications will be significantly reduced. This article presentsa managementsystem in which radiologic information is used to aid in discriminating between patients who would benefit from adenoidectomy and those who might not benefit from this procedure. Continuous refinements to the system will provide selective criteria for a complete classification system which helps to determine the specific lymphatic tissue to be removed. While the research discussed in this article is certainly not all-encompassing, it is thought to be an important step toward replacing some of the subjectivity in adenoid diagnosis. SUMMARY

A radiologic cephalometric study of the nasopharyngeal complex has provided the following information: 1. Evaluation of 200 cephalometric measurements (both frontal and lateral views) revealed eight measurementswhich were significantly related to nasopharyngeal obstruction.

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2. Four of these measurements,all relating to the adenoid (adenoid percentage, D-AD 1: PNS, D-AD2 : PNS, and D-PTV :AD) were found to be more highly significant than the others. This fact was further borne out by individual discriminant function analyses performed on various combinations of the eight variables. Thus, it was believed that thesevariables could be used in combinations to determine when nasopharyngeal obstruction was causedby adenoids. 3. Clinical norms and standard deviations were found for each of these four most significant measurements through the use of an untreated random sample of seventy-four cases. These norms may vary according to age and sex. 4. Inasmuch as no single measurement was significantly strong enough to diagnose an adenoid problem, a combinative procedure was developed to determine when an adenoid problem exists. Simply stated, the greaterthe number of the four measurements that are at least one standard deviation below normal, the more likely the existence of nasopharyngealblockage due to the adenoid. In addition, the severity of the adenoid problem can be estimated by adding the standard deviations below the norm of all four measurements.Patientswith a summation value of less than -6 are thought to have severeadenoid problems, while those with adenoid problems whose summation is more than -6 are regarded as having moderateproblems. The foregoing study and method of diagnosis can be a very useful tool in determining when adenoid tissue is sufficient in size to cause nasopharyngeal blockage with its resultant mouth breathing. We hope that this study will give the clinician greater insight in recommending adenoid removal. REFERENCES 1. Paradise,J. L., Bluestone, C. D., Bachman, R. Z., et al.: History of Recurrent Sore Throat as an Indication for Tonsillectomy: Predictive Limitations of Histories That Are Undocumented, N. Engl. J. Med. 2!Xh 409-413, 1978. 2. Kaiser, A. D.: Relation of Tonsils and Adenoids to Infections in Children Based on a Central Study of 4,100 Children Over a 10 Year Period, Am. J. Dis. Child., 1941. 3. Evans, H. E.: Tonsil and Adenoidectomy, Clin. Pediatr. 7: 71, 1%8. 4. Ashley, F. L., Sloan, R. F., Hahn, E., Hanafee, W., and

Micthke, J.: Cinefluorogmphic Study of Palatal Incompetency CasesDuring Deglutition and Phonation, Plast. Reconstr. Surg. 2% 347-364, 1961. 5. Barton, T. E., Brummett, S. W., and Sloan, R. F.: PreadenoTonsillectomy Ciuefluotography (a film avai@le from the Library of the American Dental Association, Chicago). 6. Handehnan, C. S., and Osborne, G.: Growth of the Nasopharynx and Adenoid Development From One to Eighteen Years, Angle Orthod. 46: 243-259, 1976. 7. Scammon, R. E.: Measurement of Man, Minneapolis, 1930, University of Minnesota Press. 8. Subtelny, J. D., and Koepp-Baker, H.: The Significance of Adenoid Tissue in Velophatyngeal Function, Plast. Reconstr. Surg. 17: 235, 1956. 9. Handelman, C. S., and Pruxansky, S.: The Size of the Adenoids in Normal and C.P.I. Children, presented before the Intetnational Association of Dental Research, Washington, D. C., 1%7. 10. Menashe, V. D., Fart&, C., and Miller, M.: Hypoventilation and Cor PulmonaieDue to Chronic Upper Airway Obstruction, J Pediatr. 67: 198-203, l%S. 11. Levy, A. M., et al.: Hypertrophied Adenoids Causing Puhnonary Hypertension and Severe Congestive Heart Failure, N. Engl. J. Med. 227: 506511, 1%7. 12. Limier-Aronson, S.: Adenoids: Their Effect on Mode of Bnathing and Nasal Airtlow and Their Relationship to Characteristics of the Facial Skeleton and the Dentition, Acta Oto-laryngol. Supp. 265, 1970. 13. Limier-Aronson, S., and Hemikson, C. C.: Radiocephalometric Analysis of Anteroposterior Nasophqngeal Dimensionsin 6- to 12-Year-Old Mouth Breathers Compared With Nose Breathers, ORL 39: 19-29, 1973. 14. Ricketts, R. M.: The Cranial Base and Soft Sttuctutes in Ckft Palate Speechand Breathing, Plast. Reconstr. Surg. 14: 47-61, 1954. 15. Bushey, R. S.: Alterations in Certain Anatomical Relations Accompanying the Change From Oral to Nasal Breathing, M.S. Thesis, University of Illinois, 1965. 16. Sloan, R. F., Ricketts, R. M., Brummett, S. W., Mulick, J., Bench, R. W., Ashley, F. L., and Hahn, E.: CephalometricCinefluorographic Diagnostic Criteria Utilized in Cranio-facial Problems, 1. S. Calif. Dent. Assoc. 31: 355-362, 1%3. 17 Steek, C. H., Fairchild, R. C., and Ricketts, R. M.: Forum on the Tonsil and Adenoid Problem in Orthodontics, Am. J. Orthod. 54r 485-515, 1%8. 18 Schulhof, R.: JCO Visits Rocky Mountain Data Systems, J. Clin. Orthod. 10: 12, 1975. 19. Wertz, R. A.: Skeletal and Dental Changes Accompanying Rapid Midpalatal Suture Opening, Am. J. Otthod. SS: 41-66, 1970. 20. Wertz, R. A.: Changesin Nasal Airtlow Incident to Rapid Maxillary Expansion, Angle Orthod. 38: l-l 1. 1968. Reprint requests to:

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