嗅神経系を保存するfrontal transbasal approach

Preservation of olfaction in frontal transbasal approach

I．はじめに

　傍鞍部あるいは斜台部病変に対する手術到達法のうち，従来の経前頭蓋底到達法は節骨篩板，筋骨洞を除去するため，両側嗅覚の脱落を惹起するという欠点があった．近年Spetzlerらは，前頭蓋底を構成する筋骨および眼窩骨を筋骨洞粘膜および鼻粘膜と一塊にして切離した後，腫瘍除去後これを前頭蓋底再建に用いて嗅神経系を保存する方法を報告したが^12），今回われわれはこれをさらに改良し，より簡便な到達法を考案し3例の症例に本法を行い，有用と思われたので報告する．

Lesions in the frontal base and clival area have con-ventionally been approached using the transbasal approach described by Derome and Guiot. However, this approach necessitates removal of the crista galli and sectioning of the olfactory rootlets with the associ-ated risk of anosmia and cerebrospinal fluid leak and, in addition, complex reconstruction of the frontal base is required.

We describe a new approach to deeply situated tumors in the frontal base, parasellar and clival area which is a modification of Spetzler's craniofacial approach with preservation of olfaction. In this approach, circumferential osteotomy cuts are made around the cribriform plate to permit en block removal with its attachment to both the dura and underlying mucosa. Opening of the dura is avoided and the cribri-form bone is used to reconstruct the frontal base.

Three patients underwent surgery using this ap-proach for treatment of recurrent pituitary adenoma in two cases and for clivus chordoma in one. In one pa-tient, olfactory function was not preserved because re-section of nasal mucosa was small. In the other two pa-tients, however, olfaction was preserved by creating a cribriform plate complex with a sufficient area of resec-tion of nasal mucosa and tumors were completely re-moved.

Olfaction can be preserved, CSF leakage can be pre-vented, and facial skin incision and complex frontal base reconstruction can be avoided when this technique for maintaining normal olfactory-cribriform anatomy is used in frontal transbasal approaches.