ABSTRACT
Computerized tomography (CT) of the paranasal sinuses is usually required prior to endoscopic sinus surgery. CT demonstrates both the extent of disease(s) and the anatomical variations that may predispose to rhinosinusitis and nearby vital structures that iatrogenic damage can be avoided. The authors retrospectively reviewed 88 CT scans of paranasal sinuses and orbits, performed at Srinagarind Hospital between January 1995 and February 1997. Only adult patients were included. The study showed the presence of frontal sinuses in 88% of cases (95%CI 82.3-92.5%), agger nasi cells in 92% (95%CI 87-95.6%), concha bullosa in 34% (95%CI27.1-41.6%), Haller's cell in 24% (95%CI 17.8-30.9%), Onodi cell in 25% (95%CI 19.8-32.1%), dehiscence of the internal carotid artery in 10.2% (95%CI 6.2-15.7%) and the optic canal in the sphenoid sinus in 18.2% (95%CI 12.8-24.7%). The most common olfactory fossa was type II. Haller's cell was a coincident finding not a risk factor for maxillary rhinosinusitis. Concha bullosa was a non-statistically significant, risk factor for maxillary rhinosinustis.