Jan Kumlien

Regeneration of Maxillary Sinus Mucosa following Surgical Removal Experimental Study in Rabbits

A rapid regeneration of the epithelium takes place in the maxillary sinus in rabbits after experimental operative removal of the mucosa. Two weeks postoperatively the previously denuded areas have reepithelialized. The subepithelial glands, however, do not seem to regenerate. The normal sinus mucosa contains numerous serous glands in the lamina propria, but in the regenerated mucosa these glands are replaced by dense connective tissue. Atypical glands and polyp formations are sometimes encountered, but goblet cells are sparse. Furthermore, the sinus cavity on the operated side is reduced in size compared with the nonoperated side because of fibrosis and periosteal reactions including bone degradation and neogenesis. This study indicates that although the mucosa is reepithelialized within 2 weeks, the regeneration of the lamina propria is incomplete, and reactive cellular processes such as bone remodeling, fibroblast proliferation, and formation of polyps and “atypical glands” are characteristic of regenerating mucosa.

Experimental Acute Sinusitis in Rabbits: A Bacteriological and Histological Study

A bacteriological and histological study of experimentally induced acute pneumococcal sinusitis was performed in 69 New Zealand White rabbits. The sinus ostium was blocked on one side on the first day of the experiment. On the second day, 10(7)-10(9) Streptococcus pneumoniae in 1 ml were injected into the same sinus cavity. Purulent sinusitis developed unilaterally in all rabbits. Histological examination of the sinus mucosa revealed edema, dilated venules, leukocytic infiltration of the mucosa as well as localized epithelial lesions. On staining with acridine orange at pH 4.0, the bacteria were observed in the secretion but not in the mucosa. When we used Streptococcus pneumoniae subjected to an animal passage, the bacteria were re-isolated in 9/10 infected sinuses. Neither sole occlusion of the ostium nor injection of pneumococci into a sinus cavity with a patent ostium resulted in a bacterial sinusitis. Obstruction of the sinus ostium and the use of a virulent Streptococcus pneumoniae strain were essential for the induction of sinusitis in rabbits.

Endoscopic and Caldwell-Luc Approaches in Chronic Maxillary Sinusitis: A Comparative Histopathologic Study on Preoperative and Postoperative Mucosal Morphology

The aim of the present investigation was to study the histopathologic mucosal changes occurring in chronic maxillary sinusitis both preoperative and postoperative to functional endoscopic sinus (FES) surgery and the Caldwell-Luc (C-L) operation. Correlations were also sought between the histopathologic parameters and endoscopic findings, as well as patient symptoms. Sixty sinuses with the FES surgery and 55 sinuses with the C-L procedure were studied. The histologic parameters were graded semiquantitatively and compared preoperatively and postoperatively. The C-L operation reduced almost all parameters, whereas after the FES operation only edema and inflammatory cells were significantly reduced. Fibrosis increased postoperatively with both methods. The number of inflammatory cells was closely correlated to a thickened antral mucosa and to purulent secretion. No valid correlations were found when comparing histology with patient symptoms. All in all, histologic considerations suggest that asthmatic patients with severe sinonasal polyposis might benefit from the C-L procedure.

The Vascular Arrangement of the Sinus Mucosa: A Study in Rabbits

Seventy-seven New Zealand White rabbits, with an average weight of 3 kg, were used in studies on the paranasal sinus. Replica moulds of the sinus revealed a sinus cavity composed of three compartments with a total volume of 2-3 ml. The sinus cavity was connected with the nasal cavity through an ostium. By intravascular injection of silicone rubber for dissection and of methacrylate for production of corrosion casts, the vascular bed and the vessels passing to and from the sinus cavity were studied. The main arterial supply and venous drainage takes place through the ostium, which is surrounded by a dense venous plexus. Compared with the nasal mucosa, the number of vessels per volume unit is about the same in the sinus mucosa. Many vessels perforating through the osseous walls, both arteries and veins, were found, however, indicating that the blood supply is not derived exclusively from vessels coming through the ostium.

Blood flow in the rabbit sinus mucosa during experimentally induced chronic sinusitis. Measurement with a diffusible and with a non-diffusible tracer.

Chronic sinusitis was induced in New Zealand White rabbits. Access to the sinus cavity in question was obtained through a hole drilled in the dorsum of the nose, and for induction of sinusitis either cotton wool together with a suspension of 10(8) Streptococcus pneumoniae was introduced, or this method was combined with blocking of the sinus ostium with methacrylate. In 9 rabbits (weight range 3.6-5.0 kg), blood flow was determined 5 weeks-9 months after the induction of sinusitis, at a point in time when heavy inflammatory signs were present. The blood flow was determined both with radioactively labelled microspheres 16 +/- 1.5 micron in diameter and with Rb86Cl. Cardiac output as determined with the microsphere method was 127 +/- 28 ml X min-1 X 1 000 g-1. The blood flow in the sinus mucosa was 0.60 +/- 0.16 ml X min-1 X g-1 with the microsphere method and 0.51 +/- 0.20 ml X min-1 X g-1 with use of Rb86Cl. These values did not differ significantly from the corresponding values found previously in healthy rabbits.

Induction, Course, and Recovery of Maxillary Sinusitis: A Bacteriological and Histological Study in Rabbits

A bacteriological and histological study of acute pneumococcal sinusitis in rabbits was performed. The sinus ostium was blocked unilaterally and on the second day 108 Streptococcus pneumoniae type 3 were injected into the sinus cavity. The bacteriology of the sinus secretion and the morphological alterations of the sinus mucosa was determined 1, 2, 3 and 4 weeks after initiation of infection. Initially a pronounced mucosal infiltration of granulocytes and lymphocytes was found. Squamous cell metaplasia as well as areas of desquamated epithelium were also evident. This heavy inflammatory reaction gradually declined and after 4 weeks the epithelium appeared more normal, although goblet cells and subepithelial thickening, both associated with a more chronic infection, were found in certain areas. After 2 weeks, the initially reisolated pneumococci were replaced by a nonfermentative Gram-negative flora as well as anaerobic bacteria.

Experimental acute sinusitis in rabbits. Energy metabolism in sinus mucosa and secretion.

In previous studies, sinus secretions have been analysed concerning pO2, pCO2 and pH. In this study the energy metabolism in the maxillary sinus mucosa and secretion was studied in 33 New Zealand White rabbits. In freeze-dried samples, glucose and lactate were analysed by enzymatic assays and ATP by HPLC. In the purulent sinusitis, lactate concentration in the mucosa was 5.67 mmol X kg-1 w.w. and significantly higher than in the control sinus. Also in the non-purulent sinusitis, lactate was increased in the mucosa. The lactate concentrations in the secretion were 9.8 and 8.4 mmol X kg-1 w.w. in purulent and non-purulent secretions respectively and are probably the result of a diffusion from the mucosal cells and of leukocyte metabolism. A reduced ATP content, with increases in ADP and AMP, in the sinus mucosa of the purulent sinusitis suggests a relative energy depletion which could result in impaired epithelial function.

Cellular Regeneration and Recovery of the Maxillary Sinus Mucosa: An Experimental Study in Rabbits

Unilateral maxillary sinusitis was induced in 30 New Zealand White rabbits with Streptococcus pneumoniae or Bacteroides fragilis. In another group of 15 rabbits without infection, the sinus mucosa was surgically removed in defined areas. In both series, the sinuses were serially sectioned for histological analysis of the cellular regenerative capacity. In maxillary sinusitis induced by Bacteroides fragilis, an inflammatory and also reparative process involving all mucosal layers including the underlying periosteum was seen. The more superficial trauma as found in pneumococcal sinusitis eventually led to restitution ad integrum. Following surgical removal, the denuded sinus-lining was reepithelized by a flattened ciliated epithelium on a lamina propria displaying fibrosis and lacking serous glands. The restoration of the rabbit maxillary sinus mucosa after surgical trauma thus leads to structural abnormalities of the epithelium as well as the lamina propria, and these changes are likely to interfere with the normal function of the sinus mucosa.

Blood flow in the rabbit maxillary sinus mucosa during experimentally induced acute sinusitis

The blood flow in the maxillary sinus mucosa was studied in 35 New Zealand White rabbits. The blood flow measurements were made by two methods, one with use of Rb86Cl and the other with 15 microns Sn113-labelled microspheres. With the Rb86Cl method the blood flow of the infected sinus mucosa was about 0.8 ml x min-1 x g-1 when correction was made for radioactivity in the secretion. The radioactivity found in the secretion probably reflects an increase both in vascular and mucosal permeability and in blood flow. When microspheres labelled with Sn113 were used, the mean mucosal blood flow in the presence of sinusitis was found to be 0.83 +/- 0.56 ml x min-1 x g-1. This blood flow was significantly higher than on the control side. In a control series, mere blocking of the ostium did not significantly alter the blood flow in the sinus mucosa.

Blood Flow in the Rabbit Maxillary Sinus Mucosa: Measurement with a Diffusible and a Non-diffusible Tracer

The blood flow of the sinus mucosa was studied in 11 New Zealand White rabbits. Their body weight averaged 3.5 kg. The blood flow determinations were performed during neurolept anaesthesia with continuous blood pressure recording. The blood flow in the sinus mucosa and septum, as well as in other organs, was determined both with Sn113-labelled microspheres and with Rb86Cl. Cardiac output as determined with the microsphere method was 146 +/- 36 ml X min-1 X 1000 g-1 body weight. There was a good correlation between the blood flow values obtained with the two methods. The blood flow in the sinus mucosa was 0.58 +/- 0.41 ml X min-1 X g-1 when measured with microspheres and 0.43 +/- 0.34 ml X min-1 X g-1 with the Rb86Cl technique. In the septal mucosa the corresponding values were 0.42 +/- 0.20 ml X min-1 X g-1 and 0.49 +/- 0.43 ml X min-1 X g-1 respectively.