By using CT of the nose and paranasal sinuses, we'll study the effect of nasal septum deviation on maxillary sinus volumes, assess the association between the severity and type of nasal septum deviation and the occurrence of maxillary sinusitis and compare the maxillary sinus volume on the deviated side with that of the contralateral side.

Inclusion Criteria:

1. Age ≥18 years.
2. Availability of high-resolution CT scans of paranasal Sinuses (axial, coronal, sagittal views).
3. Adequate imaging quality allowing sinus volumetry and septal deviation measurement.
4. Anatomical landmarks visible: Crista galli, hard palate, choanae, uncinate process/OMC region clearly identifiable to permit NSD measurement and sinus segmentation.

Exclusion Criteria:

1. Age < 18 years.

2. Previous sinonasal or maxillofacial surgery.

3. History of facial trauma or fractures affecting the nasal septum or sinus walls.

4. Sinonasal tumors, polyps, or large cysts.

5. Congenital craniofacial anomalies (e.g., cleft palate).

6. head and neck syndromes.

7. Cases with systemic diseases affecting growth and development.

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Patients presented to outpatient clinic at Assiut University hospital complaining of nasal symptoms like nasal obstruction, rhinorrhea ,headache, and recurrent sinusitis.