Optimal enlargement of the frontal sinus approach.

After recalling the main anatomical characteristics of the frontal sinuses, the authors describe the frontal craniotomy surgical procedure and its variants. A bicoronal skin incision is performed. An inferior-based pericranial flap is created, with its limits situated away from the osteotomies. Osteotomies are performed with an oscillating saw. The inferior osteotomy is horizontal, tangentially following the supraorbital margin as far as the lateral limit of each sinus. The osteotomy is continued medially as far as the nasion, passing an average of 3mm above the floor of the medial part of the sinuses, immediately above the frontonasal ducts. The superior osteotomy is performed in a vertical coronal plane through the summit of the sinuses. It is arc-shaped, concave downwards, joining the lateral extremities of the inferior osteotomy. The posterior wall of the sinus can be resected to perform frontal sinus cranialization, allowing access to the midline anterior cranial fossa. The posterior wall of the sinus is removed with a high-speed burr in the same way as the anterior wall. At the end of the procedure, the bone flap is sutured with nylon suture material and the pericranium is sutured over the bone flap.