Welcome in H.C.M.
I have gone through your query regarding sinusitis
not responding to medical and conservative treatment.
As you said that your C.T.Scan of paranasal sinuses
shows opacification of all the sinuses, it means you are having pan sinusitis.
Now it has to be decided that what type of pathology is behind it , this may be made by good clinical examination and culture and sensitivity of nasal discharge.
If it comes allergic than surgery will not going to help you and you will get recurrence. In allergic cases medical treatment along with avoidance of probable allergen is line of action. On the other hand if it is blockade of osteomeatal complex by hypertrophied mucosa than surgical intervention by Functional endoscopic surgery
will be the right choice.