En Bloc Ethmoidectomy Through the Combined Craniofacial Approach: Surgical Technique

Abstract

The technique of ethmoidectomy through the craniofacial approach is described. The procedure requires the combined work of a neurosurgical and an otolaryngological team and allows an en bloc resection of the whole ethmoid bone. It is, therefore, indicated in ethmoidal malignancies, as well as in benign tumours affecting the cribriform plate and/or the ethmoidal roof. The defect in the anterior cranial fossa is repaired by means of various graft materials which are glued on the surrounding bony surfaces.

This procedure, first described in the 1950s [11], has gained remarkable advantages from the introduction of fibrin sealing. Actually, repair of defect in the floor of the anterior cranial fossa after resection is made easier, tighter and safer by the possibility of glueing the graft materials.

The principle of the operation consists of coupling the classic “maxillectomy” (ethmoidectomy through the facial approach) with a wide anterior cranial fossa exposure through bifrontal craniotomy allowing an exact delineation of the upper ethmoid borders. Thus, access can be gained to all aspects of the ethmoid bone, with the obvious exception of the posterior which merges with the sphenoid. Bone cuts are performed along the suture lines (unless otherwise required by the neoplastic growth) and eventually the specimen is delivered from below.

This technique affords the main advantage of an en bloc excision of the whole ethmoid, avoiding contact with the tumour or, even worse, a piecemeal removal. If need be, the resection may be enlarged to adjacent regions, such as the frontal sinus, the orbita, the maxilla or even the contralateral ethmoid. The sole limitation is found when the sphenoid sinus is involved. In this case, the tumour projecting into the sphenoid cavity can only be “shelled out”. The one single alternative to this manoeuvre would be an onerous neurosurgical procedure, i.e. removing the sphenoid body without jeopardizing the optic nerves and the internal carotid arteries [2].

The procedure is indicated in ethmoidal malignancies, as well as in benign tumours affecting the fovea ethmoidalis and the cribriform plate [6]. A precise preoperative assessment of the neoplastic extent is mandatory. Nowadays this is almost always possible through high-definition CT, both in axial and in coronal scans. In our experience, the survey of anatomical and pathological details is facilitated when axial sections are parallel to the floor of the anterior cranial fossa.