Background: In the common cold infection, the nose and sinus mucosa react as one entity to the virus, both simultaneously demonstrating the typical inflammatory changes (Gwaltney 1994). Little is however known about whether a similar phenomenon exists in other pathological settings.
Aim: Our study examines the behaviour of the mucosa of the paranasal sinuses in comparison to the nasal mucosa, when the subject is exposed to the accused allergen.
Methods: The allergen applied was birch pollen, to which the patient had a known allergy but however took no medications and was asymptomatic at the experiment baseline. An ENT specialist examined the nasal mucosa at two visits, one before, the other after an allergen provocation tests, for signs of a nasal mucosal reaction. To assess changes in the mucosal lining of the sinuses, its thickness was measured at different points on 3 sections taken from MRI images taken at the same two visits. The area enclosed by the maxillary sinus mucosa was also measured, as well as the volume it contains, which was done by devising two different methods devising 3D reconstructions, in order to indirectly assess any possible mucosal thickness changes.
Results: There was no change detectable in the inner lining of the frontal, sphenoidal, ethmoidal and maxillary sinuses. The mean change in mucosal thickness at the different points taken was 0.45 ± 0.32 mm. All values before and after provocation lie within the physiological range for normal sinus mucosal thickness. The area enclosed by the maxillary mucosa changed by a mean value of only 1.82%. The volume measured inside each of the sinuses (right, left) changed on average by 1.035 ml, from initial volumes of 20.68 ± 1.61 ml. Meanwhile the ENT examination reported the expected typical nasal mucosal reaction, the slight variations in sinus mucosal thickness measured were considered not significant.
Conclusion: Our study reports for the first time that there is no relationship in the behaviour and response of the nose and sinus mucous membrane to test allergen exposure. When the former is provoked by an allergen, the thickness of the latter remains anatomically unchanged.