Name: Excision of Cyst in Frontal Sinus via Intranasal Approach 【Indications】 Smaller cyst, downward invasion of the sieve area, in the nasal cavity can be seen in the anterior part of the middle nasal passage bulge. Contraindications] There are no absolute contraindications, but in cases where the nasal cavity cannot see the bulge, the operation is more difficult. Preoperative preparation] Frontal sinus X-ray and body film. Anesthesia and position] Sitting or lying position is acceptable. The procedure is performed with superficial anesthesia and local infiltration. Surgical Procedure] (1) Remove the anterior portion of the middle turbinate. (2) Circularly cut away the mucosa of the middle nasal passage bulge (Figure 1). (3) For thick bone, use a round bone chisel to cut the window. For thin bone, use pointed nasal mucosa forceps to pierce into the cystic cavity. The mucus or mucopus juice is aspirated, and the cystic window is enlarged with cup forceps and back-biting forceps (Fig. 2). (4) Try to explore the condition of the nasofrontal duct channel, if the channel is very large, no further treatment, with the help of the cyst wall to maintain the epithelial surface of the channel wall; if the channel is small, it can be expanded appropriately. (5) Place the drainage tube, local filling to stop bleeding. [Intraoperative points of attention] (1) In addition to cutting away the cyst’s anterior and inferior cystic wall, attention should also be paid to the resection of the anterior portion of the middle turbinate and the opening of the anterior middle sieve chamber, so as to provide a wide open aperture to the nasal cavity. (2) Probing the nasofrontal duct and frontal sinus area from the nasal cavity, the action should be gentle, to prevent accidental entry into the skull and cause serious complications. [Postoperative treatment] Nasal gauze is removed for 3~5d, and attention is paid to the observation of the open area of the cyst for granulation and polyps. [Main complications] (1) intracranial infection: mostly due to intraoperative instruments in the posterior wall of the frontal sinus bone defect area blindly force probing, penetration of the cystic wall and dura mater caused, if careful attention, can be avoided. (2) Postoperative tearing: mostly due to excessive occlusion of the anterior inferior bone, destroying the lacrimal sac or nasolacrimal duct. Intraoperative attention should be paid to this, and if it has occurred, a silicone tube can be placed through the lacrimal duct, leading directly to the cystic cavity. (3) Narrow or closed drainage channel in the open area of the cyst and recurrence of the cyst: this complication can be avoided if attention is paid to the above operational requirements.