Main outcome measures: To completely protect the bilateral turbinates and olfactory epithelium, this procedure provides access to the sphenoid sinus by a transseptal approach via the left nasal cavity and by the olfactory cleft approach via the right nasal cavity without resecting any turbinate. A jet stream olfactometer (JSO) was used to assess the mean recognitive threshold of the left, right, and bilateral nasal passages before and after surgery.