Quantification of the presigmoid transpetrosal keyhole approach to petroclival region / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Despite the presigmoid transpetrosal approach has been used by different researchers in various ways, the surgical injury rate remains high. Applying a minimally invasive keyhole idea, we devised a presigmoid transpetrosal keyhole approach (PTKA), classified and quantitatively assessed their approach to the petroclival area on a cadaver model by using a neuronavigation system.</p><p><b>METHODS</b>The presigmoid transpetrosal keyhole approach was divided into four increasingly morbidity-producing steps: retrolabyrinthine, partial labyrinthectomy with petrous apicectomy, translabyrinthine and transcochlear keyhole approaches. Six latex-injected cadaveric heads (twelve sides) underwent dissection in which a neuronavigation system was used. An area of exposure 10 cm superficial to a central target (working area) was calculated. The area of clival exposure with each subsequent dissection was also calculated.</p><p><b>RESULTS</b>The retrolabyrinthine keyhole approach (RLK) spares hearing and facial function in theory but provides for only a small window of upper clival exposure. The view afforded by partial labyrinthectomy with petrous apicectomy keyhole approach (PLPAK) provides for up to four times this exposure. The translabyrinthine keyhole approach (TLK) and transcochlear keyhole approach (TCK), although producing more morbidity, add little in terms of a larger petroclival window. However, with each step, the surgical freedom for manipulation of instruments increases.</p><p><b>CONCLUSIONS</b>The presigmoid transpetrosal keyhole approach to the petroclival area is feasible and useful. The RLK has relatively limited utility. For lesions without bone invasion, the PLPAK provides a much more versatile exposure with an excellent chance of hearing and facial nerve preservation. The TLK provides for greater versatility in treating lesions but clival exposure is not greatly enhanced. The TCK adds little in terms of intradural exposure but should be reserved for cases in which access to the petrous carotid artery is necessary.</p>

Microsurgical anatomy of the presigmoid translabyrinthine keyhole approach / 中华显微外科杂志

Objective To design a new presigmoid translabyrinthine keyhole approach assisted by Stryker neuro-navigation system according to the keyhole idea,and observe microscopic anatomy structures, which could be.regarded as the bases of this approach in clinical application.Methods Navigation data were established on 8 cadaveric heads fixed by formalin and perfused intracranial vessels with colored silicone. A 7-cm postauricular C-shaped skin incision as we reported was performed.After elevating the skin flap and musculofascial flap,a 3.5 cm?3.0 cm bone window was made.On skeletonizing the sigmoid sinus,bony lab- yrinth and the canal for facial nerve,the presigmoid retrolabyrinthine,partial labyrinthectomy with petrous api- cectomy,translabyrinthine keyhole approaches were simulated in turn.The length of important structures ex- posed and the angle of vision were measured step by step, and the anatomic structures were observed.Re- suits The approach-correlated bone could precisely be drilled with the aid of neuro-navigation,which could avoid the bewilder in drilling process.The angles of visual field,the length of clivus andⅦcranial nerve were significantly increased after partial labyrinthectomy with petrous apicectomy or all labyrinth removal,but there were no significant difference between partial and all labyrinth removal.The retrolabyrinthine keyhole approach spares hearing and facial function but provided for limited window of petroclival region exposure.The partial labyrinthectomy with petrous apicectomy keyhole approach provided wider exposure to petroclival region,cere- bellopontine angle,prepontine region and posterior cavernous sinus;an area between theⅢ-XI cranial nerves was easily visible with an excellent chance of hearing and facial nerve preservation.The translabyrin- thine keyhole approach,producing more morbidity,provided for greater versatility in treating lesions,added little exposure of petroclival region.Conclusion The presigmoid translabyrinthine keyhole approach,which could provide excellent exposure of the petroclival region,was feasible to be performed in our study.The ap- proach-correlated bone could be precisely removed assisted by neuro-navigation system.The exposure was oh- viously increased hy partial labyrinthectomy with petrous apicectomy or all labyrinthine removal,the former provided an excellent chancre of hearing and facial nerve preservation.