Anatomical variations of the middle Turbinate among adult Sudanese Population -A Computed Tomographic Study

Objectives: This study aimed to determine the prevalence of the anatomical variations of the middle turbinate among adult Sudanese population which include Concha Bullosa (CB) and Paradoxical middle turbinate (PMT) and their relationship with age and sex. Methods: The study population involved 29 males (47.5%) and 32 females (52.5 %) with a mean age of 37 years. Exploration was done in the radio-diagnostic department of Ribat University Teaching Hospital, KhartoumSudan in the period from January to September 2018. Patients were scanned on slice collimation of 1mm thickness with a slice thickness of 4 mm. Computed Tomography (CT) scans were retrospectively reviewed for the presence of CB and PMT coronal planes, bony windows and reported the results in the datasheet. Statistical analysis was performed using SPSS and compared with previous results on similar studies. Result: In the current study, the prevalence of the CB was 22.9%, observed bilaterally in 6 cases (9.8%), unilaterally in 8 (13.1%). PMT was present only in 3 cases (4.9%) all of them were unilateral.Conclusion: Computed Tomography (CT) may easily identify such uncommon anatomic variations of the osteomeatal region, determination of these variations aids in providing a better surgical orientation and avoiding or minimizing the possible complications.


Introduction
From the lateral wall of the nasal cavity,there are three nasal conchae (turbinate bones old name called by Otorhinolaryngologist) projecting downwards 1 . The nasal turbinates are important anatomical structures within the nasal cavity 2 . While the inferior one is a separate bone, the others are parts of the ethmoid bone. Their position and relationship to other important anatomic landmarks are extremely important especially in non-invasive endoscopic skull base and ENT (ear, nose, and throat) surgical procedures 3 .
Concha bullosa is the most common anatomic variation of the osteomeatal complex region that is seen in the middle turbinate (MT)

Concha bullosa (CB):
CB is hypertrophy and pneumatization of the nasal turbinate, occurring most often in the middle turbinate and rarely noticed in the inferior or superior turbinates 4,5 .It can be uni-or bilateraland if it is unilateral then it is usually accompanied by a contralateral septal deviation 6 .Pneumatizations of all three turbinates, superior, middle and inferior (panconchabullosa) is extremely rare [7][8][9] .The supreme nasal concha of Santorini is a rare anatomic variant and the supreme concha bullosa was not previously reported 10 .
According to the location and shape of pneumatization; three variations of Concha bullosa are seen like lamellar form (pneumatization of the vertical lamella of the concha), bulbous form (pneumatization of the inferior segment) and the extensive form which is a massive pneumatization of both the lamellar and inferior parts 11 .
The medial part of the ethmoid bone forms the middle concha. As it elongates in the nasal cavity, anteriorsuperior stabilization is provided by the cribriform plate of ethmoid whereas the lamina papyricea provides posterior and lateral stabilization. The bony structure which gives attachment to the lamina papyricea is called the basal lamella. Basal lamella divides the ethmoidal air cells into the anterior and posterior groups. Pneumatization of the middle concha is an extension of the normal pneumatization of the ethmoidal air cells [11][12][13] .
Although there is anassociation of CB with sinusitis, there are also studies against this argument. It is not the existence of concha bullosa but its size was held responsible for the occurrence of sinusitis 14 . Later in following studies, sinusitis was not associated with CB, but CB is emphasized as a possible cause of sinusitis due to forming mucosal contact and obstruction in the osteomeatal complex region 15 .

The paradoxical middle turbinate (PMT):
PMT refers to an inferomedially curved middle turbinate edge with the concave surface facing the nasal septum which usually occurs bilaterally 16 . However, it is not associated with any change in the normal middle turbinate attachments. This anatomic variant alone can lead to significant narrowing of the middle nasal meatus (MNM) and impedes the normal drainage of paranasal sinuses due to ostiomeatal complex obstruction and thus resulted in sinusitis or other mucosal diseases of sinus, especially the large ones 17 .

Study design:
An observational, analytical cross-sectional study of adult Sudanese patients depending on their age and sex was conducted to determine the prevalence of clinically significant anatomical variations of the middle turbinate. The study was conducted in Khartoum, Sudan during the period from January to September 2018.

Study sample:
The study population involved 29 males (47.5%) and 32 females (52.5%) with a mean age of 37 years. Exploration carried out in the radio-diagnostic department of Ribat University Teaching Hospital, Khartoum-Sudan.

Inclusion criteria:
Patients who presented with signs and symptoms attrib uted to nasal sinuses after clinical examinations and subjected to radiological investigation.

Exclusion criteria:
Patients with congenital deformities, previous surgery, trauma or malignancy of the nose, paranasal sinuses were excluded from the study.

Data collection techniques:
Patients were scanned on slice collimation of 1mm thickness with a slice thickness of 4mm. The age and sex were recorded, CT scans were reviewed in coronal planes in bony windows and the results were reported in the datasheet.

Data analysis:
Statistical analysis was performed using SPSS version then it was presented and described by using the text, table charts, and figures.
Ethical clearence:Not needed, Retrospective case study

Samples:
This study consisted a total of 61 patients of which 29 (47.5%) were males and 32 (52.5%) were females ( Table 1). The subjects were assigned to seven age groups (age ranges from 10-80yrs) with an average age of 37 yrs (Table 2). This study encountered anatomical variations of the middle turbinate amongadult Sudanese population which include CB (pneumatised middle turbinate) and PMT (medially curved middle turbinate).

Discussion
In the present study, the frequency of anatomical variations of the middle nasal turbinate which include CB (pneumatised middle turbinate), PMT (medially curved middle turbinate) was determined.
Pneumatization of the middle concha is divided into three groups: lamellar type -the pneumatization of the vertical lamella of the concha; bulbous type -pneumatization of the bulbous segment (an inferior portion of the turbinate); extensive CBpneumatization of both the lamellar and bulbous parts 11 .The true concha bullosa is produced following pneumatization of both portions (vertical lamina and inferior bulb) of the middle nasal concha 19 . Lamellar pneumatization and conchal Pneumatization were included as a criterion in our study. Its prevalence rate was (22.9%), which matches closely to prevalance of (24%) reported 20 . But less when compared to the result reported byanother study in(35%) subjects 21 . High prevelance was reported (42.6%) and (53.6%) 22,11 . Low prevelance of (9.5%) and (11%) were reported 23,24 .The reported prevalence of CB varies widely from 4-80% in several studies 19 . Such a wide range of incidence is due to the criteria of pneumatization adopted.
Paradoxically curved middle concha in the present study was found only in 3 patients (4.9%). This finding matches closely to incidence of (5.3%) reported 25 .

Conclusions
Computed tomography (CT) is the investigation of choice for evaluating the anatomical variations of the nasal cavity and paranasal sinuses. Determination of these variations aids in providing a better surgical orientation and avoiding or minimizing the possible complications during any operative procedures. In the present study concha bullosa is the most common occurrence in the nasal cavity, but the paradoxical middle turbinate is rarely encountered anatomical variant.

Recommendations:
1) The CT scan should not be used exclusively to diagnose chronic sinusitis or to determine the need for surgery. Rather, it should be used to provide clinical data to the endoscopic examination and assist in directing surgical treatment to the affected areas.
2) It is important for the radiologist to know the anatomical variations of the paranasal sinus region to consider their possible pathological consequences.
3) Further studies of anatomical variations with a larger number of patients and clinical disease correlations are needed for more reliable and accurate results.