Signi icance of accessory opening of maxillary air sinus

Maxillary air sinus opens in hiatus semilunaris of middle meatus of the nasal cavity. Drainage of sinus should happen through a natural ori ice. That is mandatory because there are cases where there is an additional opening of sinus posterior to the hiatus semilunaris. In this case, there may be recirculation of mucus between natural and accessory opening leading to complications and recurrence of the patient’s problem during various endoscopic procedures. So noting this high signi icance of accessory opening, the present study was conducted. Total of 50 specimens (27 were from the right side, and 23were from the left side)was studied. Presence of accessory opening ofmaxillary air sinus was noted. Position of the opening was noted. The shape of the opening was noted. The diameter of the accessory opening wasmeasured using Sliding Vernier Caliper. Observations on the above parameters show the accessory opening of maxillary air sinus was present in 21 specimens out of a total of 50 specimens (42%). Typical Shape of the opening on the left side was Circular and on the right sidewasOval. The average diameter of the opening on the right side was 24mm and on the left side was 46mm. So de initely signi icance of the accessory opening of maxillary air sinus was found. That’s why surgeons, especially, Otorhinolaryngologists, should note and explore the exact position of the accessory opening of maxillary air sinus, during various sinus surgeries.


INTRODUCTION
Maxillary air sinus opens into hiatus semilunaris of middle meatus of the nasal cavity. Usually, an opening is in the posterior part of hiatus semilunaris.
However, there are incidences of additional openings, apart from usual opening. So we feel, this area should be explored in detail, to check out for the accessory opening of the sinus. Because, it is found that, despite the endoscopic surgeries on the usual opening of maxillary air sinus has been done. Still, the problem persists in some patients. And that's why there is a need to study the accessory opening of maxillary air sinus. So we decided to work on this topic.
Maxillary air sinus is developed around 2-3 months in the Maxilla bone. Maxillary air sinus drains into Middle meatus of Nasal cavity (Figure 1). Middle meatus and hiatus semilunaris are areas, where variations can occur which predispose patients to recurring sinusitis. Length of hiatus semilunaris was found to be shorter on the left side and in Females. Knowing the discrepancy of hiatus semilunaris lengths between Right and left sides and Males versus Females may guide the advancement of endoscopic instruments into the nasal cavity (Dahistrom, 2014). Anatomical variations have been suggested to play a role in the pathogenesis of chronic rhinosinusitis (Sahin et al., 2015). Recirculation of nasal mucus occurs when secretions that have been transported out of natural maxillary ostium return to sinus via a surgically created or accessory ostium (Gutman and Houser, 2003). Computerized tomography (C.T.) revealed a recirculating mucus ring between the two Ostia of the maxillary sinus (Chung, 1999). Maxillary sinoscopy via the canine fossa revealed a left maxillary sinus recirculation phenomenon. There was thick mucus coming back into the maxillary sinus through an accessory ostium, which ascended and transported into left natural ostium (Yanagisawa and Yanagisawa, 1997).
Accessory Ostia of the sinus is present in anterior and posterior nasal fontanelles, the bone de icient areas in the lateral nasal wall behind and below uncinate process (Bajaj et al., 2015). Functional endoscopic sinus surgery may be indicated when certain anatomic variations impede normal drainage of paranasal sinuses through ostiomeatal complex (Derjac-Arama et al., 2015). Management of Anatomic variations surrounding the Ostia is very important in the treatment of maxillary ostium (Tan, 1998). Paranasal sinuses are maintained in a healthy state by ventilation through individual Ostia and by a mucociliary transport mechanism that keeps a continuous protective layer of mucus lowing out of sinuses (Slack and Bates, 1998). Performing a smooth and clean sinus surgery goes hand in hand with a perfect understanding of nasal and paranasal anatomy. Any maxillary sinus opening outside the hiatus semilunaris is considered an accessory ostium. Clinical signi icance of the presence of an accessory ostium is that occasionally a circular low of mucus between the natural and the accessory Ostia could occur, leading to recurrent sinusitis (Abdulmalik and Alsaied, 2017).
Normal drainage of paranasal sinuses depends on suf icient mucociliary clearance; this is dependant on the condition of the sinus Ostia (Scott-Brown et al., 1997). Anatomy of the maxillary Ostia should be well understood by an endoscopic sinus surgeon to perform middle meatal antrostomy (Anne and Souza, 2016).
So to understand the signi icance of the accessory opening of maxillary air sinus this study was done.

Study Design
Observational Study

Study Settings
Study was conducted in the Department of Anatomy of our Institute. Total 50 specimens were studied (27 were of Right and 23 of left side). Formalin preserved cadaveric specimens were taken and washed thoroughly. Then by using Dissection instruments, Lateral Wall of the Nasal cavity was nicely exposed. Middle Nasal Choncha was dissected. Middle Meatus was explored. Accessory openings of Maxillary air sinus were noted in the Middle meatus. The shape of the opening was noted. The diameter of the opening was measured. The Sliding Vernier Caliper took measurements.

Statistical analysis
Quantitative data were summarized into maximum, minimum, mean and Standard Deviation; while Qualitative data was summarized into number & percentages. Comparison of quantitative data was made by applying unpaired 't' test while the chisquare test was used for qualitative data comparison. The difference was said to be signi icant if p was equal to or less than 0.05.

RESULTS AND DISCUSSION
Accessory opening of maxillary air sinus was located in the middle meatus of the nasal cavity, just posterior to the main opening of maxillary air sinus (Figure 2).
The accessory opening was present in 21 out of a total of 50 specimens. So presence is 42%. Out of 21, on the Right side were 12 (57.1%) and on Left side were 9 (42.8%) (Figure 3).
The shape of the accessory opening is mainly Oval on the Right side (Table 1) and Circular on the Left side ( Table 2).
The average diameter of the accessory opening on Right was 24mm. and on Left was 46mm (Table 3).
According to our study, Accessory Maxillary Ostium (AMO) was present in the posterior part of the middle meatus, behind the main opening of maxillary air sinus. As noted by Abdulmalik S. Alsaied, it is located in posterior fontanelle, posterior to the natural ostium (Abdulmalik and Alsaied, 2017). According to Gray's Anatomy, maxillary sinus communicates with the lower part of hiatus semilunaris through an opening in anterosuperior part of its base; a second ori ice is frequently seen in, or immediately below, the hiatus. Both are nearer the roof    than the loor of the sinus (Williams and Warwick, 1980). According to our study, Accessory Opening of Maxillary Air Sinus was present in 21 out of a total of 50 specimens. So presence is 42%. Out of 21, on Right side were 12 (57.1%) and on Left were 9 (42.8%).
As per the study of Kumar H et al., AMO was present in 9 out of 30 half heads studied. In 6 half-heads, these were present on the right side while in 3, they were on the left side (Kumar and Choudhry, 2001). As mentioned by Manju Singhal et al., AMO was found in 20 out of 108 half heads (18.5%). Out of these 20 half heads, in 12(60%) half heads AMO was present on the right side while in remain-ing 8(40%) half heads, it is on the left side (Singhal and Singhal, 2014). As studied by M.Jog and G.W.McGarry, it occurred in four per cent (Jog and McGarry, 2003). As Cappello ZJ noted, there is typically only one ostium per maxillary sinus; however, cadaver studies have shown 10% to 30% have an accessory ostium (Cappello and Dublin, 2018).
According to our study, Shape of the Accessory Opening of Maxillary air sinus is mainly Circular on the Left side and Oval on Right side. As per the study of Kumar H et al., AMO were round or oval (Kumar and Choudhry, 2001). As mentioned by Manju Singhal et al., the shape is round or oval (Singhal and Singhal, 2014). So our indings correlate with the above authors.
According to our study, Average Diameter of the Accessory Opening of Maxillary air sinus on Right was 24mm and on Left was 46mm. As per the study of Kumar H et al., AMO diameter being 0.5mm to 3mm. (Kumar and Choudhry, 2001). As noted by Abdulmalik, the average diameter is 1.5mm (Abdulmalik and Alsaied, 2017). As mentioned by Manju Singhal et al., the diameter is 0.5 to 5mm (Singhal and Singhal, 2014). So as compared to these author's indings, our study got a comparatively large diameter of the accessory opening of maxillary air sinus.
As diameter range is more, ENT surgeons need to explore Maxillary Accessory Opening properly before heading for surgery. In our study, Diameter of Accessory Opening of Maxillary Air Sinus, as compared with Right and Left side, was Moderately Statistically Signi icant. (p= 0.06).
AMO was variation seen in nearly three-fourths of the cases (Prasanna and Mamatha, 2010). Anatomical variations of the lateral wall of the nasal cavity may create technical dif iculties during endoscopic sinus surgeries (Souza et al., 2014). So these variations need to be kept in mind by OtoRhinoLaryngologists during Endoscopic interventions and Sinus Surgeries. Primarily, when Main Maxillary Ostium is obstructed, then, enlarging the Maxillary Accessory Ostium may provide Maxillary sinus aeration.

CONCLUSION
Accessory opening of maxillary air sinus was located in middle meatus of the nasal cavity, just posterior to the main opening of maxillary air sinus. The shape of the accessory opening was mainly Oval on Right side and Circular on Left side. The average diameter of the accessory opening on Right was 24mm and on Left was 46mm. The accessory opening was present in 21 out of a total of 50 specimens. So presence is 42%. As the presence of accessory opening is 42%, it indicates a high prevalence of accessory opening. And that may create a problem for normal drainage of mucus through natural ostium. Because mucus might recirculate from natural ostium towards accessory opening leading to reentering of mucus into the maxillary sinus, causing maxillary sinusitis. Considering this high significance of accessory opening, Our study put one step ahead in attracting the attention of ENT (Ear, Nose and Throat) surgeons where one needs to be very careful during endoscopic sinus surgeries.