硬膜外前床突起一塊切離整復法

Extradural en bloc Removal and in situ Replacement of the Anterior Clinoid Process

Ⅰ．はじめに

　浅く広い術野を得るために，頭蓋底手術は日常のものとなってきた．前床突起切除はその方法の1つである．前床突起切除の硬膜外切削には，安全で迅速な低侵襲手技が求められる．われわれは従来のドリルで削る概念を一新し，前床突起を安全に一塊として切り取り整復する手術法を開発した．本法は，ドリリングより短時間で，かつドリルの熱による視神経損傷を起こさない．また，一過性動眼神経麻痺あるいは術後の眼球陥凹などを生じさせないといった利点もある．低侵襲手術にかなう高付加価値手術（value-added surgery）である．

　Extradural removal of the anterior clinoid process (ACP) is useful and essential for approaching aneurysmal and tumor lesions in and around the cavernous sinus. A safe,rapid and less invasive technique is beneficial for this basic skull base surgery. We developed a new technique by sharply cutting the ACP together with the part of the sphenoid ridge bone followed by complete replacement. A series of patients with either basilar top or internal carotid artery aneurysms underwent the present technique. After frontotemporal craniotomy,the lateral frontal and anterior middle cranial fossae are exposed extradurally. The bone was cut using a cutting steel burr from the sphenoid ridge to the superior orbital fissure and to the optic canal. By sharply separating the meningo-orbital band between the dura propria and the periorbital fascia,the ACP is exposed. The cutting burr runs underneath the ACP. By leaving a very thin sheet of bone,the entire bone piece was elevated after fracturing the thin bone using a chisel. By severing the carotid ring,the internal carotid artery is freed and mobile either laterally or medially to obtain an ample basal cistern. After operation,the once removed clinoid process is replaced in situ using a titanium plate screw. Extradural en bloc removal and in situ replacement of the ACP can be safely done by this cutting procedure. This can provide a good cosmetic result without causing enophthalmos or transient oculomotor palsy.