Ιστοπαθολογικές αλλοιώσεις του βλεννογόνου των κάτω ρινικών κογχών μετά την εφαρμογή νέων τεχνικών μεθόδων

Abstract

According to the principles of modern functional nasal surgery, the ideal technique for the surgical management of inferior nasal turbinate (INT) hypertrophy should strike a balance between optimal volume reduction and preservation of mucosa functions, especially that of mucociliary clearance.The aim of the present thesis was to investigate histological changes and wound healing process of INT mucosa after submucosal tissue volume reduction using ultrasound (US) energy, radiofrequency (RF) energy and monopolar electrocautery (MEC). Our secondary goal was to estimate the suitability of the sheep as an experimental model for the exploration of INT mucosa wound healing postoperatively.We conducted a prospective, comparative, randomized, blinded and controlled trial, based on experimental protocol in a sheep model. Twenty three animals were included in the study. INTs of 18 animals were subjected to submucosal coagulation using US, RF or MEC (n = 12 INTs per method). One, three or eight weeks postoperatively, INTs were totally removed in order to be studied histologically (n = 4 INTs per time point for each method applied). The control group (CG) consisted of 5 animals (n = 10 INTs) representing the preoperative histological picture of INT mucosa. After the application of hematoxylin - eosin staining, five basic parameters were estimated, stromal fibrosis, submucosal edema, engorgement of venous sinusoids, inflammation reaction and epithelial cell necrosis. Histological grading of the changes was performed semi - quantitatively using a 4-point scale (0 = absence, 1 = mild, 2 = moderate, 3 = pronounced). Statistical analysis of the data was performed.US - group revealed pronounced fibrosis (Median Value (MV) = 3), impressive reduction of stromal edema and evident reduction of venous sinusoids’ engorgement (p < 0.001, p < 0.001 and p = 0.058, compared with CG, respectively) by the end of the 1st postoperative week already. Severe inflammation reaction, which was present in the primary phase, declined rapidly, approaching the preoperative picture by the end of 3rd week (p = 0.070). Relatively limited areas of partial epithelial necrosis were initially observed. Thereinafter, the degree of necrosis became extremely low, getting close to normal 3 weeks postoperatively (p = 1). In the RF - treated group, fibrosis became severe enough (MV = 2.5), while edema and venous sinusoids’ engorgement were considerably decreased compared with CG (p = 0.074 and p = 0.008 respectively) by the end of 3rd postoperative week. Inflammation resolved and epithelial necrosis restored 8 weeks after surgery (p = 0.356 and p = 1, vs CG, respectively). Additionally, in all postoperative cases a well-defined intact basement membrane was present across the US and RF - treated areas. In MEC - group, fibrosis, acute inflammation reaction and epithelial necrosis presented an obviously instable progression between samples of different time points. Moreover, 8 weeks postoperatively, we observed relatively poor degree of fibrosis (MV = 1.5), marked inflammation and pronounced congestion of venous sinusoids, with significantly different values compared with the parameters found in US-group and RF-group at the same time point (p = 0.061, p < 0.05 and p < 0.05 respectively), along with a notable degree of epithelial necrosis compared with CG (p = 0.020). Furthermore, the method failed to diminish significantly the congestion of INT erectile tissue regardless of the time point studied (p ≥ 0.236 vs CG). Occasionally, the continuity of the basement membrane was focally disrupted.In conclusion, submucosal coagulation of INT using US and RF energy could establish significant and stable shrinkage of the turbinate, while providing regular rapid wound healing and respect to the epithelium, parameters that justify a minimally invasive behavior. MEC may be considered as an insecure choice, since it reveals questionable and unpredictable ability in alleviating nasal obstruction caused by INT hypertrophy along with delayed wound healing process and potential noxious effect on turbinate epithelium. Finally, the sheep seems to be a suitable model for the histological study of INT wound healing following surgical manipulations.