Histochemical detection of lymphatic drainage pathways in the middle nasal meatus.

Following extensive middle meatal antrostomy, even without manipulation inside the maxillary sinus, a reactive edema of the maxillary sinus mucosa may be subsequently detected. A presumptive correlation has been established between this particular mucosal reaction and insufficient maxillary lymphatic drainage. Histochemical examination of the lymphatic drainage pathways was carried out on surgical specimens. During the performance of surgical maxillary fenestrations, 80 surgical specimens of the middle nasal meatus were obtained including adjacent parts of the medial maxillary wall. The specimens were subjected to visualization of lymphatic vessels based on the histochemical detection of 5'-nucleotidase according to Werner (1993). Both the nasal and the maxillary sinus mucosa showed a distinct superficial and deep longitudinal lymphatic capillary network (15-200 mu phi) with an orientation towards the natural maxillary sinus ostium. The density of the network increased from cranial to caudal, from dorsal to ventral and reached maximum density at the natural maxillary ostium. Lymphatic vessels of the maxillary sinus mucosa were thin but numerous in comparison to nasal vessels. The maxillary lymphatic capillary network showed direct connections to the nasal vessels, not only along the mucosal folds of the primary maxillary sinus ostium, but also in most cases (57%) transmurally through the natural bony gaps of the uncinate process. Grünwald's theory (1910) which states that lymphatic drainage of the maxillary sinus is established exclusively along the mucosal pane through the natural ostium was disproved. Maxillary mucosal congestion subsequent to extensive middle meatal antrostomy may be explained by ablation of the intramural and transmural lymphatic drainage pathways.