|LETTER TO THE EDITOR
|Year : 2013 | Volume
| Issue : 1 | Page : 62-64
Incidental paranasal sinus abnormality on cranial computed tomography in a Nigerian population
Olalekan I Oyinloye1, Jumai H Akande1, Biodun S Alabi2, Olushola A Afolabi2
1 Department of Radiology, University of Ilorin/University of Ilorin Teaching Hospital, Nigeria
2 Department of Otorhinolaryngology, University of Ilorin/University of Ilorin Teaching Hospital, Nigeria
|Date of Web Publication||7-Mar-2013|
Olalekan I Oyinloye
Department of Radiology, University of Ilorin Teaching Hospital, Ilorin
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Oyinloye OI, Akande JH, Alabi BS, Afolabi OA. Incidental paranasal sinus abnormality on cranial computed tomography in a Nigerian population. Ann Afr Med 2013;12:62-4
|How to cite this URL:|
Oyinloye OI, Akande JH, Alabi BS, Afolabi OA. Incidental paranasal sinus abnormality on cranial computed tomography in a Nigerian population. Ann Afr Med [serial online] 2013 [cited 2020 Nov 28];12:62-4. Available from: https://www.annalsafrmed.org/text.asp?2013/12/1/62/108261
Plain film radiographic examinations, the historical standard, is rapidly being replaced by computed tomography (CT) in the diagnosis of rhinosinusitis in Nigeria, especially with availability of more CT scan machines in most tertiary institutions in the last 10 years in Nigeria. Sinus disease is often reported as an incidental finding in patients undergoing CT for non-sinus related pathologies, which sometimes leads to referrals to otolaryngologists.  The importance of such findings is difficult to interpret without a baseline knowledge of the incidence of sinus disease in the general population. 
The study aims to determine the prevalence of incidental abnormalities of paranasal sinus disease in patients undergoing cranial CT scans for indications other than sinus diseases.
We conducted a retrospective study, involving 100 consecutive patients referred for cranial CT examinations, from January 2010 to January 2011 at the Radiology Department of the University of Ilorin Teaching Hospital, Ilorin, Nigeria.
Patients were mainly referred from the neurologists, neurosurgeons and ophthalmologists to exclude intracranial pathology. Indications for scanning included headache, stroke, suspected intracranial tumour, and seizures. Patients referred primarily for suspicion of sinus disease were excluded from the study. Ethical approval was secured from the hospital authority.
Images were acquired with General Electric (GE) 4 slice Bright Speed CT machine. Two mm slice thickness for the base of the skull and 5 mm thickness for the remaining part of the brain. The sinuses were examined at window settings of 1200 with a level of 200 HU. Scanning parameters includes 105 Ma, 130 KVp and tube rotation time of 1.5 s. Serial axial images from the base of the skull to the vertex were examined in each patient focusing on the paranasal sinuses (frontal, maxillary, sphenoidal and ethmoidal). Presence of air-fluid levels or mucosal thickening was regarded as positive findings.
The incidence of involvement of different sinuses was evaluated and extent of sinus opacity evaluated for each sinus group, according to the Lund and Mackay radiological grading system.  The Lund-Mackay staging system summarized in [Table 1].
|Table 1: Lund and Mackay radiological staging for chronic rhinosinusitis|
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Since patients were primarily referred for cranial CT, and coronal scans where not routinely performed, we could not assess the osteomeatal complex, and as such, it was not included in the scoring system. The maximum Lund-Mackay score was therefore 20 instead of 24.
Data was analyzed descriptively using Statistical Package for Social sciences. (SPSS) version 15 and results were presented in tables and figures.
A total of 100 patients were involved in the study, consisting of 63 males and 37 females with a male to female ratio of 1.7 to 1.0. The mean age was 42.7 ± 20.3 with age range of 11 to 76 years.
The mean total sinus score (Lund and Mackay) was 1.09 ± 1.71, with a range of 0-6.
Incidental sinus disease was found to occur in 35%, i.e., Lund and Mackay score of equal or greater than 1, while no abnormality was seen in 65% (Lund and Mackay score of 0). Twenty two patients (22%), had a score of between 1 and 3, while 13 patients (13%) had a score of 4 and above [Table 2].
|Table 2: Distribution of Lund Mackay scoring of cranial computed tomography scans|
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Mucosal abnormality was commonest in the anterior ethmoids (34%), followed by the maxillary antrum (30%), frontal sinus (13%) posterior ethmoids (12%), and least occurring in the sphenoidal sinus (11%).
Because of the high sensitivity of the CT scan for mucosal inflammation in the paranasal sinuses, it is indeed possible that the CT scan can identify "incidental" mucosal findings that do not represent true "sinus" disease.  This extreme sensitivity of the CT scan may lead to over diagnosis on a radiographic basis. 
The incidence of sinus opacification in studies mostly from western countries have been reported to vary between 17 and 43. ,,
A total of 35% of patients in this study had sinus opacification, which is within the range in Western countries.
The most commonly affected sinus group in this study was the ethmoid sinuses, followed by the maxillary sinus. Similar pattern was reported by Hiari, et al. in a Jordanian population,  and Flinn, et al.,  who prospectively evaluated 100 patients in Edinburg, United Kingdom.
Possible explanation for the relatively higher incidence of involvement of the ethmoidal sinus is the fact that the ethmoidal sinuses are the only paranasal sinus to undergo cyclical mucosal volume changes. ,
These changes are also observed in the turbinates, nasal septum, lateral nasal wall, nasal cavity floor and the nasolacrimal ducts and these changes do not affect the frontal, maxillary, or sphenoid sinuses.
The Lund-Mackay system quantifies radiographic findings on the sinus CT scan with a numerical score ranging from 0 to 24. Currently, it is the most widely accepted scoring. It allows straight forward and reproducible analysis of mucosal changes and can be taught quickly to those with no formal radiological training. 
Previous studies have attempted to evaluate the significance of the Lund-Mackay scoring system, Bhattacharyya and Fried  proposed Lund score cutoffs clinically useful in separating patients with and without chronic rhinosinusitis (CRS)-based on radiographic criteria. They found that Lund scores of 0 or 1 were very unlikely to represent CRS and thus could be considered "negative" for CRS. Scores equal to or above 4 were considered to be indicative of CRS. Scores of 2 or 3 were equivocal, and they suggested that additional weight be placed on clinical or endoscopic criteria for the diagnosis of CRS.
Applying the cut off points for normal, equivocal, and abnormal has been stated by Bhattacharyya and Fried; 13% of patients in this study may be said to have CRS, which may require otorhinolaryngologist consultation, and 22% patients may be described as having insignificant disease.
In conclusion, incidental sinus disease is relatively common on routine cranial CT scans among Nigerian adults. The ethmoidal sinus is the most commonly affected sinus hence Lunds and Mackay scoring system is advocated in assessing the significance of paranasal sinus disease, and should be correlated with clinical symptoms.
Patients with Lund and Mackay score of less than 4 on sinus CT, without clinical symptoms would not likely require treatment.
| References|| |
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[Table 1], [Table 2]