Radiological and Audiological Assessment in Patients with Adenoid Hypertrophy Undergoing Adenoidectomy

Abstract

Enlarged adenoids in children can lead to obstruction of the ET, leading to negative intratympanic pressure and development of Otitis media effusion. Adenoid-nasopharyngeal ratio (ANR) on lateral radiograph of nasopharynx, is one of the most reliable and cost-effective ways of determining the size of adenoids with respect to the nasopharyngeal space. Patients who were clinically diagnosed with adenoid hypertrophy, above the age of 5 years, undergoing adenoidectomy were included in the study. Lateral nasopharynx radiograph, Pure tone audiometry (PTA) and tympanometry were performed. The ANR calculated, graded, and compared with the PTA, tympanograms and size on endoscopic assessment. Taking 0.835 as cut-off value, significant correlation of ANR with PTA and impedance (p = 0.002) was found. 71% abnormal PTA and tympanogram was found with ANR > 0.835 whereas 30.8% with ANR < 0.835. ANR is a useful adjunct as a pre-operative tool for determining the need for adenoidectomy in paediatric patients who are not easily willing to undergo endoscopic evaluation. A major drawback is the lack of identification of lateral extent of adenoids.

Introduction

Adenoid hypertrophy is one of the most common disorders in children. Adenoid size varies from one child to another and within the same individual as they grow. In general, normal adenoids attain their maximum size between ages of 3–7 years and then regress slowly [1].

Adenoids can become chronically infected and act as a reservoir in upper respiratory infections with resultant oedema and obstruction of the nasopharyngeal end of the eustachian tube (ET), leading to Otitis media effusion (OME). Enlarged adenoids can also lead to mechanical obstruction of the ET, can partially or totally obstruct nasal respiration leading to mouth breathing, snoring, hyponasal speech, sleep apnoea and sinusitis.

Lateral radiograph of nasopharynx is one of the most reliable and cost-effective ways of assessing the size of the adenoids. It provides an estimate of the absolute size of the adenoids and also its relation to the size of the airway [2]. Adenoid-nasopharyngeal ratio (ANR) is used to estimate the size of adenoids in relation to the space available. ANR correlates well with adenoid measurement and its pathological and surgical implications [3]. Pure Tone Audiometry (PTA) is the standard measurement tool for evaluating the degree and type of hearing loss. Tympanometry provides an effective screening test for the detection of negative middle ear pressure. It is rapid and reliable even in infants [4]. Both these tests are applied to identify and quantify hearing loss associated with OME.

To establish a correlation between the adenoids and development of OME and its implications on hearing, this study was conducted to correlate the size of adenoids to abnormalities of middle ear pressure leading to impairment in normal hearing mechanism.

Methods

This cross-sectional study was done over 18 months. Patients aged 5 years and above, clinically diagnosed as adenoid hypertrophy and undergoing adenoidectomy were included. Patients with acute upper respiratory tract infection, tympanic membrane perforation, craniofacial anomalies, cleft palate and congenital ear deformities were excluded.

All patients with symptoms suggestive of adenoid hypertrophy were subjected to radiographic examination in the form of X-ray nasopharynx-lateral view (Digital). Focus-film distance was 140 cm, and X-ray exposure settings were 70 kV, 12 mA, for 0.40–0.64 s. The beam was centred to the external auditory meatus with head in true lateral position. Patients were asked to breathe exclusively through the nose with their lips gently sealed. Radiographs done within four weeks prior to surgery were included. To calculate the adenoidal size (A), the distance between the outermost point of adenoid shadow and the line along the spheno/basiocciput was measured. To obtain nasopharyngeal size (N), the distance between posterior edge of the hard palate and Basiocciput was measured. Adenoid Nasopharyngeal Ratio (ANR) was calculated by dividing adenoidal size to nasopharyngeal size and the grading was done as per classification system by Hamza SB et al. [5].

Tympanometry along with measurement of middle ear pressure was conducted on all patients using Maico model MI-44 impedance audiometer. Conductive hearing loss was estimated as the Air–Bone gap in decibels (dB) and classified as normal (≤ 25 dB), mild (26–40 dB), moderate (41–60 dB), severe (> 60 dB) as per WHO grading. All patients also underwent endoscopic adenoid grading at the time of adenoidectomy prior to start of procedure and graded as per Clemens endoscopic classification [6]. Findings of audiological and radiological examination were then correlated, and statistical analysis was applied. Significance level was set as p value of less than 0.05.

Results

A total of 57 patients were included, of which most of the patients were in the age group 5–7 years (42.1%). The mean age was 9.04 ± 3.37 years.

Mouth breathing (94.7%), nasal obstruction (43.9%) and snoring (78.9%) were the most common complaints. Otoscopic examination of the patients revealed normal intact tympanic membrane in over 60% of ears. Dull and retracted tympanic membrane was the most commonly observed pathological finding.

Lateral nasopharyngeal radiograph showed ANR- Grade 2 (0.51–0.75) in 10.5% and grade 3 (0.76–1.00) in 89.5% of the patients. On PTA of right and left ears, normal hearing was seen in 37(64.9%) and 33 (57.9%) patients and mild hearing loss in 14 (24.6%) and 20 (35.1%) patients. 27 patients (47.4%) had bilateral normal hearing, 14 (24.6%) had bilateral abnormal hearing while 16 (28.1%) had unilateral abnormal hearing.

Type A tympanogram was seen in a little over half the patients in either ear. Bilateral abnormal results were seen in 42.1%, and unilateral abnormal tympanograms in 10.5%. (Table 1).

Table 1.

Impedance results

Outcome	N	%
Both normal	27	47.4
Bilateral abnormal	24	42.1
Unilateral abnormal	6	10.5
Right abnormal	3	5.3
Left abnormal	3	5.3

On endoscopic evaluation, 47.4% of patients showed Grade 3 and 43.9% of patients had Grade 4 adenoids as per Clemens classification. (Table 2).

Table 2.

Endoscopic adenoid grade among patients as per Clemens classifications

Adenoid grade	Description	N	%
Grade I	Adenoid tissue filling 1/3 of the vertical portion of the choanae	0	0
Grade II	Adenoid tissue filling 1/3–2/3 of the choanae	5	8.8
Grade III	Filling 2/3 to nearly complete obstruction of Choanae	27	47.4
Grade IV	Complete choanal obstruction	25	43.9

A final diagnosis of chronic adenoid hypertrophy without OME was made in 61.4% of the patients and of unilateral OME in 14% and bilateral OME in 24.6%. Comparison between ANR and endoscopic adenoid grading was done using Fisher’s exact test and p-value was calculated showing a non-significant correlation between the two. (p-value = 0.315).

Hearing loss association with the ANR was insignificant statistically but the relationship of mean ANR to hearing loss, showed significant correlation in the left ear values (p-value = 0.041) (Tables 3 and 4). No significant relationship was found between impedance and ANR grades or with mean ANR. However, taking 0.835 value of ANR as cut-off value, we found significant correlation of ANR with PTA values and with impedance findings (p = 0.002). (Table 5).

Table 3.

Distribution of ANR among patients according to PTA grade (RIGHT)

PTA grade (Right)	N	ANR grade				p-value	Mean ANR	p-value
		Grade 2 (n − 6)		Grade 3 (n − 51)
		N	%	N	%
Normal	37	5	13.5	32	86.5	0.318	0.82	0.069
Slight/Mild	14	0	0	14	100		0.87
Moderate	6	1	16.7	5	83.3		0.83

Table 4.

Distribution of ANR among patients according to PTA grade (LEFT)

PTA grade (Left)	N	ANR grade				p-value	Mean ANR	p-value
		Grade 2 (n − 6)		Grade 3 (n − 51)
		N	%	N	%
Normal	33	5	15.2	28	84.8	0.614	0.82	0.041
Slight/Mild	20	1	5	19	95		0.86
Moderate	4	0	0	4	100		0.86

Table 5.

ANR distribution and Overall Outcome of PTA and Impedance

	N	ANR				p-value
		> 0.835 (Total n = 31)		≤ 0.835 (Total n = 26)
		n	%	n	%
Overall PTA outcome
Abnormal	30	22	71	8	30.8	0.002S
Normal	27	9	29	18	69.2
Overall impedance outcome
Abnormal	30	22	71	8	30.8	0.002S
Normal	27	9	29	18	69.2

Discussion

Under normal conditions the pressure in middle ear is maintained equal or close to atmospheric pressure by the functional ET [7]. ET dysfunction is the most important factor in the pathogenesis of OME [8]. Obstruction of the ET leads to increased negative middle ear pressure, while there is influx of bacteria and viruses from the nasopharynx following adenoidal infection in these patients. This causes mucosal oedema, inflammation, and increased secretory activity of the middle ear mucosa, leading to effusion [2]. Untreated OME may result in series of consequences in the form of poor speech and intellectual development and permanent anatomical distortions within the middle ear cavity. What may be more important regarding the harmful effects of adenoids is not the absolute size, but more the size in relation to that of the nasopharynx. The degree of encroachment of hypertrophic adenoid tissue upon the Torus tubarius/ET orifice depends on the total area of the nasopharynx [8].

Clinical examination of children with nasal obstruction is unreliable. Anterior rhinoscopy may be normal or show increased secretions with or without inferior turbinate hypertrophy. In some children, examination of the nasopharynx with a posterior rhinoscopy mirror will identify large adenoids. Unfortunately, in many children it is impossible to assess the adenoids in this way. Nasal endoscopy of the nasopharynx to assess the size of adenoid tissue at the time of surgery is probably the gold standard, while mirror examination underestimates choanal occlusion, and palpation of the adenoid tissue before surgery is a poor measure of adenoid hypertrophy [6]. When endoscopy is not tolerated by the patient, estimation of the adenoid size with lateral soft-tissue radiograph of the nasopharynx is considered helpful and usually correlates well with endoscopic assessment of adenoid size.

Lateral radiograph of nasopharynx provides an estimate of the absolute size of the adenoids and also its relation to the size of the airway [2]. The absolute size of the adenoids and the size and shape of the nasopharyngeal space are major factors that determine nasopharyngeal obstruction. The ratio of these two sizes can provide a simple arithmetic measure of nasopharyngeal obstruction [9].

PTA is non-invasive, inexpensive, easy to perform and reliable even in younger patients, provided they can understand their role. It is the primary tool used to evaluate the type and degree of hearing loss. Tympanometry is the graphical representation of the admittance or compliance of the middle ear. The mobility or compliance of tympanic membrane is maximum when air pressure in middle ear is equal to that of external auditory canal and the membrane is thus free from stress. It is a simple, non-invasive, objective and a widely accepted procedure in determining the presence or absence of OME.

In our study, there was no significant correlation on analysing the relationship between endoscopic adenoid grade and ANR. Caylakli et al. [10] demonstrated significant correlation between ANR and nasal endoscopic examination findings and emphasized on ANR as an easily applicable, noninvasive method that can correctly measure the size of the adenoid tissue. Talebian et al. [3] showed that ANR had significant correlation with real adenoid measurement (pathologic and surgical measurement).

Study by Al-Kindy et al. [11] concluded that radiological examination has limited role in management of adenoid hypertrophy whereas in a study conducted by Kolo et al. [12] the adenoidal–nasopharyngeal ratio was concluded as reliable method in assessing the nasopharyngeal airway in children with obstructive adenoids.

Endoscopic adenoid grade calculated in our study was based on classification given by Clemens et al. [6] which is based on the size and obstruction of the choana by adenoid tissue whereas the lateral nasopharyngeal radiograph determines the adenoid size by calculating the AP length. Hence, there can be adenoid hypertrophy causing nasal symptoms but not the aural symptoms as the growth is more towards choana thus obstructing it. In this case the endoscopic grade can be higher whereas the radiological grading may not give useful information in determining the need for surgery.

Egeli et al. [13] concluded that middle ear pressures were found lower in children with ANR greater than 0.71 than in children ANR less than 0.71 and the difference was significant (p < 0.001). Kappadi et al. [14] also demonstrated that the number of type B and C tympanograms were significantly greater in children with ANR higher than 0.70. In our study the number of B and C type tympanograms were significantly greater in the children with ANR higher than 0.835 as compared to the ones with the ratio of lower than 0.835. This was also same for the PTA findings, as the number of patients with abnormal hearing profile were significantly greater with the ANR higher than 0.835. Tuohimaa et al. [15] reported that the size of the adenoids had a nearly significant effect on the pre-operative intratympanic pressure (p < 0.05).

Our study only included patients that underwent adenoidectomy. Those patients who had improved on medical management form a significant proportion of patients with adenoid enlargement but were excluded from the study. X rays were not repeated just before surgical intervention to avoid exposure to radiation and the actual adenoid size may have changed with medical management in a few cases. Another confounding factor is that many of our patients have received primary care elsewhere and their treatment records are unavailable. At the time of performing hearing evaluation, there is the potential of variation in medical management received between two patients. Furthermore, we have excluded patients who had tympanic membrane perforations. The perforations may have been the result of the otitis media developing as a sequelae of adenoid enlargement.

Conclusion

Through this study, it was observed that there was no significant correlation between adenoid size on lateral nasopharyngeal radiograph below ANR 0.835 but higher than this the PTA as well as Impedance audiometry showed positive correlation. ANR can be used as a pre-operative tool for planning adenoidectomy in patients symptomatic of adenoid hypertrophy but not as an isolated screening test. At the same time a new grading system needs be developed for the assessment of adenoid hypertrophy using ANR which can be standardised. One major drawback of using ANR as a tool is its lack of determining the lateral extent of adenoid hypertrophy which can be overcome by using endoscopic examination to some extent.

Author Contributions

D: Concept, Design, Data collection, Data analysis, Manuscript preparation. SKS: Concept, Design, Data analysis, Review. NG: Concept, Design, Data collection, Review. RG: Concept, Design, Review. RRV: Data analysis, Manuscript preparation, Review.

Funding

Nil.

Availability of Data and Material

Available.

Declarations

Conflict of interest

The authors declare that they have no conflict of interest.