The aim of this study is to compare the outcomes of endoscopic pre lacrimal recess approach, canine fossa approach and middle meatal antrostomy approach regarding:

1. Assessment of the accessibility of each approach to visualize and reach the different walls and recesses of the maxillary sinus.
2. Any intraoperative or postoperative complications.
3. Any post-operative recurrence or residue detected by endoscopic examination or by MSCT scan.

The maxillary sinus is the sinus most commonly affected by disease.. It varies greatly in size, shape, position and pneumatisation, not only in different individuals, but also in different sides of the same individual .

A broad spectrum of disease processes can involve the maxillary sinus, such as infective, odontogenic and neoplastic. In simple cases, a standard uncinectomy and middle meatal antrostomy may be sufficient for visualisation and clearance of disease but despite this a drawback still exists in both external and intranasal surgical procedures. Compromise of the inferior turbinate (IT) and nasolacrimal duct (NLD) is often unavoidable .

According to the anatomy of MS and the feature of diseases originated from MS assessed with multi-angulated telescopes, including 30 ,45 and 70 telescopes, with kinds of curved instruments, there are still some areas which can not be viewed and handled . Such critical areas as the inferior, lateral, anterior wall, zygomatic recess, alveolar recess and prelacrimal recess of maxillary sinus are difficult to approach. For this reason other approaches are needed like canine fossa approach (CFA), prelacrimal recess approach (PLRA) and medial maxillectomy approach.

Review of the literature revealed no meta-analysis or evidence based medicine comparing different endoscopic approaches to maxillary sinus regarding feasibility of the access to different recesses and residual lesions.

The endonasal endoscopic prelacrimal recess approach (PLRA) provides a clear view through wide access to all walls of the maxillary sinus while still preserving the nasolacrimal duct and inferior turbinate.

It enables us to accurately, mini-invade and completely remove MS lesions. It is a physiological and functional surgery, and has great advantages in treating the diseases of the nasal cavity.

Canine fossa approach (CFA) has been proposed as an alternative method of obtaining access to the maxillary antrum. Although a few studies have demonstrated the benefits of CFA in management of the severely diseased maxillary sinus, the efficacy and superiority of this method compared with conventional MMA require further investigation above all considering new microdebrider blades that can be inserted through the antrostomy.

• Active Comparator: The middle meatal antrostomy approach.

  The middle turbinate will be gently moved medially. Then uncinectomy is the next step which will be performed in numerous ways. Once the natural ostium will be identified, an ostium seeker will be placed through the ostium and then carefully will be pushed posteriorly to widen the ostium.

  Using a through-cutting forceps, the ostium will be enlarged.

  Intervention: Procedure: Endoscopic Approaches To Maxillary Sinus
• Active Comparator: The endoscopic prelacrimal recess approach
  A curved incision will be made between the anterior aspect of the IT and the posterior end of the nasal vestibule.the mucoperiosteum will be lifted posteriorly.Bone removal will be achieved. the anterior bony portion of the medial wall of the MS will be removed, .then the IT-NLD flap will be formed.The prelacrimal recess will be opened
  Intervention: Procedure: Endoscopic Approaches To Maxillary Sinus
• Active Comparator: The canine fossa approach.

  It will be done either transnasally or transorally:

  ** The transoral approach through a sublabial incision : CFA consist in a trocar placed in the canine fossa.After removal of the trocar a 4-mm microdebrider blade will be placed through the passage created by the trocar.

  ** The transnasal approach: A curved incision will be made between the anterior aspect of the Inferior Turbinate and the posterior end of the nasal vestibule,the mucoperiosteum will be lifted posteriorly Then the investigators will reach the anterior wall of the maxillary sinus through bone removal which will be achieved using a gauch and hammer and a high-speed electric drill.

  Intervention: Procedure: Endoscopic Approaches To Maxillary Sinus

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Inclusion Criteria:

• Age more than 18 years,
• Incidence of extensive denovo or recurrent sinonasal polyposis,
• Denovo or recurrent cases of antrochoanal polyp,
• Incidence of both denovo or recurrent allergic fungal rhinosinusitis,
• Maxillary sinus cysts and mucocoel,
• Presence of MS tumours such as inverted papilloma
• Presence of vascular tumours,
• Presence of sinonasal malignancies extending to the maxillary sinus,
• Having no contraindications for surgery under general anaesthesia.

Exclusion Criteria:

• Age less than 18 years,
• Refusal of the patient,
• Having contraindications for surgery.