• cypress pollen;
  • intermittent allergic rhinitis;
  • leucotriene C4;
  • nasal provocation test;
  • sinus tomodensitometry;
  • sinusitis

Background:  Involvement of paranasal sinuses has been suggested in allergic rhinitis but not clearly demonstrated.

Aims:  To investigate the relationship between intermittent allergic rhinitis and computerized tomography (CT).

Methods:  Twenty patients with intermittent rhinitis and sensitized to cypress pollens underwent unilateral nasal provocation tests (NPTs) using increasing concentrations of cypress pollens out of the pollen season. Sinus CT-scans were carried out just before a NPT and 24 h later. Nasal lavage was carried out just before a NPT, 30 min after a positive challenge and again 24 h later. Leucotriene C4/D4, intracellular adhesion molecule-1 and eosinophil cationic protein were measured in nasal secretions.

Results:  Thirteen patients (65%) showed an alteration in their CT-scans after allergen challenge. Ten of them showed sinus changes controlateral to their allergenic provocation. Radiological changes mainly affected the osteomeatal complex and the ethmoid sinuses. Pre-existing abnormalities (13 of 20 cases) mainly concerned the maxillary sinuses. There was no correlation between CT-scan abnormalities and levels of mediators released in nasal secretions.

Conclusions:  We have shown that nasal allergen challenge can produce radiological changes in the paranasal sinuses. This mainly concerned the ethmoid sinuses.