Concha bullosa of the inferior turbinate: an unusual cause of nasal obstruction

SUMMARY

Turbinate pneumatisation, also known as concha bullosa, refers to the existence of an air cell inside the turbinate. While pneumatization of the middle and superior turbinates are common, the presence of pneumatization of the inferior turbinate, otherwise known as an inferior concha bullosa is very rare. Herewith, a case is presented of bilateral hypertrophy of the inferior turbinates associated with a left inferior concha bullosa.

Introduction

The turbinates are important structures arising from the lateral wall of the nose. There are normally three turbinates: the superior and middle turbinates are part of the ethmoid bone and the inferior turbinate is a separate bone in itself. The inferior turbinate bone also articulates with the ethmoid, palatine and lacrimal bones (completing the medial wall of the nasolacrimal duct). Occasionally there may be a fourth turbinate called the supreme turbinate.

The middle turbinate is smaller and projects downwards over the openings of the maxillary and ethmoid sinuses, and act as buffers to protect the sinuses from coming into direct contact with pressurized nasal airflow. Most of the inhaled airflow travels between the inferior turbinate and the middle turbinate. The inferior turbinate is the largest turbinate, and is responsible for the majority of airflow direction, humidification, heating, and filtering of air inhaled through the nose. Turbinates are composed of a pseudostratified columnar ciliated respiratory epithelium with a thick, vascular and erectile glandular tissue layer.

Large, swollen turbinates may lead to blockage of nasal breathing. Allergies, exposure to environmental irritants, or a persistent inflammation within the sinus, can lead to turbinate swelling ¹. Deformity of the nasal septum can also result in enlarged turbinates ¹. Less common, an enlargement of the inferior turbinate can be due to the presence of a concha bullosa (CB) ^2-8.

Case report

A 24-year-old female came to our attention complaining of a 4-year history of rhinorrhoea and nasal obstruction. She has a history of snoring and frequent sneezing and is also asthmatic. Clinical examination showed large turbinates that were abutting the septum. She was treated with xylometazoline and mometasone without improvement in her symptoms. She was referred to the Otorhinolaryngology allergy clinic and skin prick tests were positive for dog and house dust mite. A computed tomography (CT) scan of her paranasal sinuses was performed. This showed a small amount of polypoid mucosal thickening bilaterally in the maxillary antrum and ethmoid air cells. The left infundibulum was occluded due to apposition of the left uncinate process and a Haller cell. The inferior turbinates were hypertrophic and a concha bullosa was visible on the left side (Figs. 1, 2).

Fig. 1.

Coronal CT scan shows hypertrophic inferior turbinates with left concha bullosa.

Fig. 2.

Axial CT scan shows hypertrophic turbinates with left concha bullosa.

The patient underwent functional endoscopic sinus surgery under general anaesthetic. Intra-operative examination showed hypertrophy of the inferior turbinates (Fig. 3). A 4 mm 0 degree rigid endoscope was used and the inferior concha bullosa (ICB) was resected removing the free edge of the inferior turbinate using turbinectomy scissors (Fig. 4). The uncinate process was removed and a middle meatal antrostomy was performed bilaterally. Nasal douching with isotonic sterile saline solution was prescribed, three times a day, for 10 days. The patient was reviewed in the Clinic after one month and her nasal obstruction had improved significantly.

Fig. 3.

Enlargement of the left inferior turbinate due to a concha bullosa.

Fig. 4.

Intra-operative view showing the air cell inside the left inferior turbinate.

Discussion

The inferior turbinates are the largest of all the turbinates, and are responsible for the majority of airflow direction, humidification, heating, and filtering of air inhaled through the nose.

Usually enlarged inferior turbinates are the result of infections, allergies, exposure to irritants, such as cigarette or cigar smoking, vasomotor rhinitis and chronic infection in the sinuses. A deviated nasal septum may cause compensatory enlargement of the contralateral turbinate. It is very unusual for enlargement of the inferior turbinate to be due to an ICB. One of the most important hypotheses regarding the aetiology of the ICB is correlated with its embryology. The inferior turbinate has two chondral lamella and two separate ossification centres. These appear between the 5^th and 7^th months of foetal development and fuse by the 9^th month. During this period, the epithelium may invaginate into the double lamella and form a potential CB ^3-9. Another hypothesis suggests that during foetal life, maxillary sinus pneumatisation extends into the inferior turbinate ⁵. Yang et al. found this correlation in 8 out of 18 ICBs (44%) ¹⁰.

In 1988, Zinreich et al. were the first to recognise ICB as an anatomical variant of the turbinates ¹¹.

Only a few papers, in the English literature, describe ICB and most of these have appeared as case reports ^{1 3 4 7 8}. Aydin et al. described two cases of ICB, one of which was diagnosed incidentally during a CT scan performed for a mass of the hard palate. The other patient complained of nasal obstruction, sneezing, nasal discharge and facial pain due to bilateral ICB ². Christmas et al. described three cases of ICB presenting with nasal obstruction ⁶. Yang et al. described a large retrospective study of 59,238 paranasal CT scans and found 16 to have ICB, two of which bilateral ¹⁰.

ICB is normally asymptomatic and diagnosed incidentally upon imaging ^2-5. It can, however, when there is extensive pneumatisation, cause nasal obstruction ^{1-5 9 12} as in our case. Other symptoms associated with ICB are nasal discharge, nasal discomfort with coexistent infection, headache and epiphora ^{8 12-14}. Clinically, it is virtually impossible to differentiate between hypertophy of the inferior turbinate and an ICB. Use of vasoconstrictor drugs may be useful in the clinical setting to differentiate between a CB and reversible mucosal disease. Definitive diagnosis is made with a CT scan of the sinuses.

Bolger et al. classified CB of the middle turbinate into three types: pneumatisation of the vertical lamella, pneumatization of the inferior bulbous and "true" CB that include both ¹⁵. In our case, the pneumatisation was localized in the inferior bulbous of the inferior turbinate.

Treatment of the ICB is indicated only when it is symptomatic. The goals of treatment are to maximize the nasal airway, to preserve nasal mucosa function, and to minimize complications. Medical treatment such as steroid nasal sprays may be attempted, but often are not successful in these cases and surgery is required. Many surgical techniques have been described such as out-fracture of the inferior turbinate and crushing of the ICB with forceps, excision of the free edge of the inferior turbinate using turbinectomy scissors, submucosal diathermy and turbinoplasty with the use of the microdebrider ^{3-5 16}. A concha that is pneumatised anteriorly without any posterior involvement can be treated by partial turbinectomy, removing only the anterior portion preserving as much of the turbinate as possible. Curved scissors should be placed at the neck of the turbinate just above the bulge of the area of the pneumatisation with the curve pointing inferiorly. In the event of very large pneumatisation, a lateral turbinectomy may be used as described by Dogru et al., in 1999. They described resection of the ICB removing the lateral aspect of the inferior turbinate ⁹ and since then many other Authors have used this method ^{7 8}. Although this technique is easy and quick to perform, it is contraindicated where there is a communication between the ICB and maxillary sinus, because it can produce an inferior meatal antrostomy leading to mucociliary recirculation problems ⁹. Unlu et al. suggest making a vertical incision with a sickle knife, along the antero-inferior surface of the turbinate and then they use Blakesley-Wilde forceps to remove the inferior mucosa from ICB ⁵. In small CB, crushing may be enough to alleviate nasal obstruction. In this technique, the turbinate is grasped with pituitary forceps or using a Freer dissector inserted between the septum and the turbinate and directed laterally to crush the turbinate against the lateral wall or inserting the Freer dissector lateral to the CB and crushing it against the septum ¹⁷. Total turbinectomy is contraindicated because it can increase the risk of the patient developing atrophic rhinitis, in particular in hot and dry climates ¹⁸.

Conclusions

ICB is a rare entity. It is usually diagnosed incidentally on CT scan, but can, as in our case, present with nasal obstruction. ICB must be considered as a potential cause of nasal obstruction, in particular when there is no response to vasoconstrictor drugs. It is best treated surgically and there are various techniques for resecting the ICB.