Choanal Atresia
In this congenital abnormality the back of the nose fails to open up during development leaving a bone and membrane plate that needs surgical treatment.
I have some 20 years of experience of this surgery using a technique with a special endoscope placed through the mouth to visualise the back of he nose. A special microdebrider gives excellent control as the area is carefully enlarged to give an oversize opening as there is always a degree of restenosis (narrowing)
see presentations on choanal atresia and airway obstruction