Endoscopic Sinus Surgery Section 5 (قسمت پنجم فایل) Bakhshaee M, MD Rhinologist, Assistant Prof. MUMS

Frontoethmoidectomy Frontal Sinusotomy (I, II, III)

Frontoethmoidectomy This procedure involves opening of the frontal recess together with an anterior ethmoidectomy

Frontal sinusotomy I No instrumentation of the frontal recess is required when the uncinate process is attached to the skull base or middle turbinate; when the uncinate process has been removed, the recess is open unless there are: Large agger nasi air cells Bulla frontalis Supraorbital cell

Frontal sinusotomy II Enlarging the frontal recess by the submucosal removal of agger nasi air cells, bulla frontalis, or a supraorbital cell.

Frontal sinusotomy III Extended enlargement with removal of the frontonasal spine or “beak”.

There are few other reasons for operating on the frontal recess before trying a partial anterior ethmoidectomy. These include: The presence of fungal disease in the frontal sinus Mucocele Osteoma Other pathology in this area that requires wide exposure for access.

Access to the frontal recess may be altered by the attachment of the uncinate process

Type A Where the uncinate process attaches to the lateral nasal wall so the frontal sinus drains into the middle meatus

Type B1 The uncinate process attaches to the skull base

Type B2 The uncinate process attaches to the middle turbinate

Agger Nasi & Bulla Frontalis A high anterior ethmoidal cell that has pneumatized into the frontal bone is called the bulla frontalis and this can displace the frontal recess posteriorly

Supraorbital cell The supraorbital cell extends up into the frontal sinus posterior to the frontal recess. Supraorbital cell can extend over the skull base

Surgical Technique The surgeon must have a good reason for operating in this area. The landmarks that will help you are the remains of the uncinate process, the remainder of the anterior wall of the ethmoid bulla, and a knowledge of the air cells from the CT scan.

Uncapped agger nasi cells, the terminal recess, and the ethmoid bulla form domes that are joined together. It often appears that this is all there is and they might fool you into thinking that one of them is a small frontal sinus.

The aim is to open this crevice, which will turn out to be the pathway to the frontal recess and the frontal sinus, by “deflating” the cells. This is best done by passing the ball probe well above their domes and gently lateralizing them.

Anterior ethmoid artery You should not go searching for the anterior ethmoid artery as it is not a useful landmark and to do so is dangerous. It is important to be aware that it is partially dehiscent in 20% of patients. If the skull base is very well pneumatized, the artery can even be free like a tightrope, especially if there is a large supraorbital cell.

Sphenoethmoidectomy This is an extension of a partial anterior ethmoidectomy that involves surgery into the posterior ethmoid sinuses and the sphenoid sinus

Sphenoid sinusotomy A sphenoid sinusotomy is a transnasal approach to open the sphenoid sinus Sphenoid sinusotomy can be classified into types I, II, and III depending on its size.

Onodi Cell A sphenoethmoid (Onodi) cell has part of its extension lateral to the lateral wall of the sphenoid, which means that the optic nerve is likely to be exposed

Anatomy Its natural ostium lies high in the anterior wall of the sphenoid and can be hidden by the superior and middle turbinates The roof of the sphenoid sinus is a reliable landmarkand the posterior ethmoid sinuses do not drop below this horizontal level of the skull base

The vomer meets the sphenoid in the midline, but the sphenoid inter sinus septum is symmetric in over 75% of patients

The lateral wall of the sphenoid contains the carotid artery, which is dehiscent in 30% of patients

The superolateral aspect of the sphenoid sinus contains the optic nerve, which is visible in 20% of patients

Surgical Technique

The posterior ethmoidal cells are entered through the basal lamella and it is safest to enter these medially and inferiorly. Enlarge access to these cells and avoid making a tunnel. Always find the sphenoid sinus transnasally first if you intend opening up all the posterior ethmoid sinuses.

landmarks to avoid traversing the boundaries of the paranasal sinuses Check the CT scan to see that there is no Onodi cell as the optic nerve can sometimes be dehiscent in its lateral wall. Look at the posterior coronal CT slices of the maxillary sinus and look at the height from the roof of the maxillary sinus to the roof of the skull base. Sometimes this can be spacious but sometimes it is small and it will give the operator an idea of the extent of the posterior ethmoidal air cells.

Landmarks The roof of the sphenoid sinus is a useful landmark as the posterior ethmoid sinuses are not lower than it. The posterior ethmoid sinuses that lie medial to the medial wall of the maxillary sinus in a sagittal plane can be removed without concern that the optic nerve or orbit will be damaged.