Mucosal regeneration following sinus surgery : an experimental study and clinical study

The investigations described in this thesis concerned functional and structural aspects of the regenerated sinus mucosa following sinus surgery.

In a biopsy material collected pre- and postoperatively from patients with chronic maxillary sinusitis, randomized for treatment with either Functional Endoscopic Sinus Surgery (FESS) or the Caldwell-Luc procedure (CL), histological parameters were evaluated semi-quantitatively and correlated to endoscopic findings and patients' symptoms. A greater reduction of inflammatory parameters was seen following CL than after FESS. Endoscopic findings of purulent secretion were correlated to number of inflammatory cells and degree of submucosal thickening. No correlation was found between histopathology of the mucosa and patients' symptoms or the number of antibiotic courses.

In rabbit models of two surgical procedures, namely modified radical operation (MRO), i.e. removal of sinus mucosa without ostial interference, and middle meatal antrostomy (MMA) i.e. widening of the natural sinus ostium, the regenerative capacity of healthy as well as of infected sinus mucosa was studied by: 1. examining whole-mounted nose-sinus complexes by light microcopy; 2. vascular castings and immunohistochemistry on histological sections of the regenerated microcirculatory network; 3. blood flow measurement using a non-diffusible tracer, radiolabelled microspheres (Sn 113); 4. evaluation of vasoreactivity to the [alpha]2-adrenoceptor agonist and vasoconstrictor oxymetazoline by means of laser Doppler flowmetry; and 5. investigating the reinnervation of healthy rabbit sinus mucosa following surgical removal, by means of a double-labelling immunocytochemical technique, using a monoclonal antibody to protein gene product 9.5 (PGP) combined with antibodies directed against neuropeptide Y (NPY), or tyrosine hydroxylase (TH).

The maxillary sinus mucosa of the rabbit became re-epithelialized with a respiratory ciliated epithelium by 1 to 2 months postoperatively. In the lamina propria, however, there was an increased number of vessels and nerve fibres as well as an increase in fibrosis. The submucosal glands did not regenerate, even after 9 months.

In induced sinusitis, both MMA and MRO led to a decrease in the inflammatory features of the sinus mucosa. Nevertheless, persistent local histopathology remained abundant in the ostial region following MMA surgery, irrespective of whether there was previous infection or not. Moreover, morphological changes, often specific for the inducing agent, remained postoperatively in the sinus cavities, which became colonized with rabbit nasopharyngeal flora.

The blood flow in the sinus mucosa was not significantly affected by sinus surgery, whether the procedure included the natural ostium or not. However, the regenerated sinus mucosa was more sensitive to a locally applied vasoconstrictor, implying a modified vasoreactivity.

Thus, the regenerated sinus mucosa displays several altered features, structurally as well as physiologically. It is conceivable that these reactions are present in all parts of the regenerating paranasal sinus mucosa, and should be considered when deciding on the surgical approach.