Accepted Manuscript Transnasal endoscopic and lateral approaches to the clivus: a quantitative anatomical study Francesco Doglietto, MD, PhD, Marco Ferrari, MD, Davide Mattavelli, MD, Francesco Belotti, MD, Vittorio Rampinelli, MD, Hussein Kheshaifati, Davide Lancini, MD, Alberto Schreiber, MD, Tommaso Sorrentino, MD, Marco Ravanelli, MD, Barbara Buffoli, PhD, Lena Hirtler, MD, PhD, Roberto Maroldi, MD, Piero Nicolai, MD, Luigi Rodella, MD, MSc, Marco Maria Fontanella, MD PII:
S1878-8750(18)30391-7
DOI:
10.1016/j.wneu.2018.02.118
Reference:
WNEU 7533
To appear in:
World Neurosurgery
Received Date: 17 December 2017 Revised Date:
18 February 2018
Accepted Date: 19 February 2018
Please cite this article as: Doglietto F, Ferrari M, Mattavelli D, Belotti F, Rampinelli V, Kheshaifati H, Lancini D, Schreiber A, Sorrentino T, Ravanelli M, Buffoli B, Hirtler L, Maroldi R, Nicolai P, Rodella L, Fontanella MM, Transnasal endoscopic and lateral approaches to the clivus: a quantitative anatomical study, World Neurosurgery (2018), doi: 10.1016/j.wneu.2018.02.118. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Doglietto and Ferrari
ACCEPTED MANUSCRIPT
Transnasal endoscopic and lateral approaches to the clivus: a quantitative anatomical study Francesco Doglietto,1 MD, PhD,* Marco Ferrari,2 MD,* Davide Mattavelli,2 MD Francesco Belotti,1 MD, Vittorio Rampinelli,2 MD, Hussein Kheshaifati,1,3 Davide Lancini,2 MD, Alberto Schreiber,2 MD, Tommaso Sorrentino,2 MD, Marco Ravanelli,4 MD, Barbara Buffoli,5 PhD, Lena
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Hirtler,6 MD, PhD, Roberto Maroldi,4 MD,& Piero Nicolai,2 MD,& Luigi Rodella5 MD, MSc,& Marco Maria Fontanella,1 MD& 1
Neurosurgery, 2Otorhinolaryngology-Head and Neck Surgery, and 4Radiology, Department of
Medical and Surgical Specialties, Radiological Sciences, and Public Health;
Department of Neurosurgery, Prince Sultan Military Medical City, Riyadh, Saudi Arabia
5
Anatomy and Physiopathology, Department of Clinical and Experimental Sciences;
6
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University of Brescia, Brescia, Italy
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3
Department of Systematic Anatomy, Center for Anatomy and Cell Biology, Medical University of
Vienna
Corresponding Author:
Neurosurgery
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Francesco Doglietto, MD, PhD
Department of Medical and Surgical Specialties, Radiological Sciences and Public Health University of Brescia
25123 Brescia, Italy
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Largo Spedali Civili, 1
Phone: +39 030 3995587
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Fax: +39 030 3995008
Email:
[email protected]
* These Authors equally contributed to the study &
These Authors equally contributed to the study
Keywords: anatomy; clivus; comparative study; transnasal endoscopic; far-lateral; lateral approaches; quantitative study; retrolabyrinthine; retrosigmoid; skull base surgery; transclival; translabyrinthine
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Doglietto and Ferrari
ACCEPTED MANUSCRIPT Abstract
Background: Transnasal endoscopic approaches to the clivus have been recently established. Comparative analyses with "classic" lateral approaches are limited. Objective: To compare transnasal endoscopic and lateral approaches to the clivus, quantifying
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exposure and working volume of each approach in the anatomy laboratory. Materials and Methods: Five injected specimens (10 sides) underwent high-resolution computed tomography. In each specimen, transnasal endoscopic (Paraseptal, Transrostral, Extended Transrostral, Transethmoidal, Extended Transclival approach without and with intradural
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hypophysiopexy) and lateral approaches (Retrosigmoid, Far-lateral, Presigmoid retro- and translabyrinthine) to the clivus were performed. An optic neuronavigation system and dedicated software (ApproachViewer-GTx-UHN, Toronto, Canada) were used to quantify working volume and
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exposed clival area of each approach. Statistical evaluation was performed with Kruskal-Wallis test and Steel-Dwass-Critchlow-Fligner post-hoc test.
Results: Endoscopic transnasal transclival approaches showed higher working volume and larger clival exposure compared to lateral approaches. Incremental volumetric values were evident for transnasal approaches; pre-sigmoid approaches provided less working volume than retrosigmoid
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ones. A transnasal transclival approach with hypophysiopexy provided significant exposure of the upper clivus (84.4%). The transrostral approach was the first transnasal approach providing satisfactory access to the midclivus (66%); retrosigmoid and far-lateral approaches provided exposure of approximately half of it. The lower clivus was optimally exposed with endoscopic
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transclival approaches (83%), while access to this region was limited with lateral approaches. Conclusions: This quantitative anatomical study shows that endoscopic transnasal approaches to
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the clivus provide larger working volume and wider exposure of the clivus than lateral approaches.
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Doglietto and Ferrari
ACCEPTED MANUSCRIPT Introduction
In the past two decades, transnasal endoscopic surgery has become a cornerstone in the treatment of lesions of the skull base and adjacent areas.1-4 However, the optimal surgical approach is still matter of debate for lesions in challenging sites, such as the clival area.5-11 Endoscopic transnasal transclival approaches (ETCAs) provide a median corridor to the clivus by
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exploiting the nasal cavities to create a working space that is free of major nerves and vessels. ETCAs can be subdivided in upper, middle, and lower routes, which can be combined according to the need for exposure and surgical maneuverability.12 The lateral boundaries of the corridor can be expanded up to the cavernous sinus,13,14 inferior petrosal sinus, and hypoglossal nerve.15
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ETCAs have gained wide favor in recent years, replacing most median approaches to the clivus. They were first for extradural disease involving the clivus and petroclival junction and have been progressively adopted to resect lesions with transdural and intradural extensions (such as
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chordomas,16 chondrosarcomas,9 meningiomas,17 and aneurysms of the posterior fossa18). Their major drawback is the need for skull base reconstruction, which can be challenging due to the geometry, dimension, and site of the defect; in case of intradural pathology, ETCAs are still associated with a relatively high post-operative CSF-leak rate.6,7,17-19
Surgical options to expose the clivus include lateral transcranial corridors, with retrosigmoid7 and
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far-lateral19 approaches being the most widely used, together with retro- and trans-labyrinthine approaches. They provide exposure of the clivus with a diagonal trajectory and imply crossing a number of neurovascular structures.
In this preclinical anatomical study, the most commonly used transnasal and lateral approaches to
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the clivus were compared using a novel research tool based on an optic neuronavigation system and dedicated software, which quantifies the working volume and exposure of a surgical corridor.20 The aim was to provide objective and quantitative data to describe the most commonly used
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surgical approaches to the clivus in terms of working space and surgical exposure.
Material and methods
Five cadaveric heads (10 sides) were used. Three fixed specimens were provided by the Medical University of Vienna; 2 fresh-frozen specimens by Medcure® (USA). Fixation had been performed with immersion technique in a 20% alcohol solution. The arterial system was injected in every specimen with red-stained silicon. The median age of donors was 69 years (range: 59-80) with the following gender distribution: 2 females and 3 males. All specimens were dissected at the Anatomy Laboratory of the University of Brescia.
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Each specimen underwent multidetector computed tomography (CT); DICOM files were uploaded on dedicated software (ApproachViewer,20-24 part of GTx-UHN, University of Toronto, Toronto, Canada) coupled with an optical neuronavigation system (NDI Polaris® Vicra®, Waterloo, Canada). All specimens presented a sellar type25,26 sphenoid sinus. A neuronavigation registration error of less than 1 mm was considered acceptable for quantifications. The ApproachViewer was used to
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quantify exposed clival areas and volumes of surgical corridors obtained with each approach. A high definition (HD) endoscopic camera (Karl Storz®, Tuttlingen, Germany) with 4 mm 0°, 30° or 45° Rod-lens Hopkins endoscopes (Karl Storz®, Tuttlingen, Germany) was adopted. A complete set of instruments for endoscopic transnasal skull base surgery was used (Karl Storz®, Tuttlingen,
for lateral approaches, together with endoscopic assistance.
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Surgical approaches
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Germany). A surgical microscope (OPMI 1-FC, Carl Zeiss®, Oberkochen, Germany) was employed
The following endoscopic transnasal corridors were performed and quantified (Figure 1A-F): •
Paraseptal (PS) approach: removal of the anterior wall of the sphenoid sinus was performed between the nasal septum medially, superior turbinate laterally, planum sphenoidale superiorly, and floor of the sphenoid sinus inferiorly (Figure 1A).23
Transrostral approach (TS): disarticulation of the ethmoidal perpendicular plate from the
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•
sphenoid and removal of the rostrum sphenoidale were performed. The resulting rhomboid, median window was bounded by the superior turbinates supero-laterally and orbital processes of the palatine bones infero-laterally (Figure 1B).23 Extended transrostral approach (ETS): bilateral removal of the superior turbinates and orbital
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•
processes of the palatine bones were performed. The resulting window was squared and bounded by the planum sphenoidale superiorly, sphenoid floor inferiorly, and residual posterior •
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ethmoidal cells bilaterally (Figure 1C).23 (Posterior) Transethmoidal approach (TE): removal of posterior ethmoid cells, exposing the lamina papyracea (Figure 1D), was performed.23 •
Transnasal endoscopic transclival approach (ETCA): posterior-inferior septectomy, submucoperiosteal and sub-muscular dissection of the nasopharyngeal posterior wall and removal of the sphenoidal floor were performed. The clivus bone was then drilled between the sellar floor superiorly, paraclival internal carotid arteries (ICAs) and hypoglossal canal laterally, and foramen magnum inferiorly (Figure 1E).11,27
•
ETCA with intradural hypophysiopexy (pituitary transposition) (TCH): the sellar and tuberculum sellae were drilled and removed. Inferior hypophyseal pedicles and anterior inter4
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cavernous sinus(es) were sectioned. The periosteum and dura of planum sphenoidale and tuberculum sellae were incised on the midline together with the diaphragma sellae up to the pituitary stalk. The entire pituitary gland was upturned in the suprasellar cistern. Once fully exposed, the dorsum sellae was drilled out (Figure 1F).28
•
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The following transcranial lateral approaches were performed and quantified (Figure 2A-D): Presigmoid retrolabyrinthine infratentorial approach (RL): a retroauricular C-shaped incision was made from just superior to the pinna, at the base of the zygomatic root,29,30 extending to the mastoid tip, and passing around the pinna, two fingers29 (i.e. one inch31) posterior to the mastoid
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process. Next, the skin flap was elevated anteriorly. An open mastoidectomy was performed and the sigmoid and superior petrosal sinuses were exposed. The labyrinth was exposed and the lateral, posterior, and superior semicircular canals were identified and preserved. The dural
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triangle bounded by the labyrinth anteriorly, superior petrosal sinus superiorly, and the sigmoid sinus posteriorly, was incised after sectioning the endolymphatic duct. Finally, the incision was completed in a T-shaped fashion29,31 (Figure 2A). •
Presigmoid translabyrinthine infratentorial approach (TL): after performing a presigmoid retrolabyrinthine approach, the labyrinth was drilled up to the internal auditory canal (IAC),
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which was opened with full exposure of its content.29-31 After completing the drilling, the dura deep to the labyrinth was uncovered, and the T-shaped incision was extended anteriorly following the increased exposure29 (Figure 2B). •
Retrosigmoid approach (RS): After identifying the position of the transverse sinus along the line
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connecting the zygomatic arch and the inion,32,33 a curved-vertical incision was made two fingers behind the insertion of the pinna, approximately centered over the Asterion.32 The mastoid, petrous, and occipital bones were exposed. The burr hole was placed on the asterion
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and a sub-occipital craniectomy was performed.33 An inversed T-shaped dural incision was made to elevate two triangular dural flaps towards the transverse and the sigmoid sinus and one dural flap downward, thus maximizing the exposure33 (Figure 2C). •
Far-lateral approach (FL): a hockey-stick incision along the posterior midline of the neck, approximately down to the level of C4 was made.34 The skin flap was elevated and the trapezius, sternocleidomastoid, splenius capitis, longissimus capitis, and semispinalis capitis muscles were sequentially reflected to expose the sub-occipital triangle between the superior oblique, inferior oblique, and posterior rectus capitis muscles.34,35 The vertebral artery was identified and completely exposed by reflecting inferiorly the rectus capitis muscle detached from the inferior nuchal line.34,36 A suboccipital craniotomy extending to the midline medially, 5
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to the inferior nuchal line superiorly, to the foramen magnum inferiorly, and to the occipital condyle laterally, was performed.34-37 Supero-laterally it was combined with the retrosigmoid craniotomy reaching the transverse–sigmoid junction.34,35,37 The hemilaminectomy of C1 was then completed by removing the ipsilateral half of its posterior arch.34,35,37,38 Finally, the dural incision made for the retrosigmoid approach was extended inferiorly in a curvilinear
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fashion.34,35,39 (Figure 2D).
Endoscopic surgical corridors were performed as modular approaches (extending from the less invasive to more extended approaches). Among lateral approaches, retrosigmoid approach was
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always firstly performed and randomly followed by presigmoid approaches or far-lateral approach. Focusing on presigmoid approaches, the retrolabyrinthine approach was always performed before
Surgical corridor quantification
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the translabyrinthine approach.
After simulation of each surgical approach, quantification of the operating corridor was obtained with dedicated software (ApproachViewer,20 part of GTx-UHN; University of Toronto, Toronto, Ontario, Canada) and an optical neuronavigation system (Polaris Vicra®; NDI, Waterloo, Ontario,
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Canada). For endoscopic approaches, deep and superficial surfaces of the surgical corridor were tracked with a navigated probe by drawing the perimeter of the exposed portion of the clivus and pyriform aperture, respectively.
tracking
the
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For lateral approaches, the following corridors between neurovascular structures were quantified available
volume
between
the
external
cortical
bone
plane
of
the
•
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craniotomy/craniectomy and clivus (Figure 3): Pathway 1: between the trigeminal stem and acoustic-facial bundle both above (1a) and below (1b) the abducens nerve. •
Pathway 2: between the acoustic-facial bundle and glossopharyngeal nerve.
•
Pathway 3: between the vagus nerve superiorly, hypoglossus nerve inferiorly, and spinal root of accessory nerve anteriorly.
•
Pathway 4: between the hypoglossus nerve and first cervical root.
The vertebral artery was displaced but left intact during volume tracking. Cerebellar displacement was optimized and kept constant with brain retractors. According to the trajectory of each surgical approach, the pathways were quantified as follows (Figure 3): retrosigmoid approach (pathways 1a, 1b, 2, and 3), far-lateral approach (pathways 1a, 6
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1b, 2, 3, and 4), retrolabyrinthine approach (pathways 1a, 1b, and 2), and translabyrinthine approach (pathways 1a, 1b, 2, and 3). The global working volume of each lateral approach was obtained as the sum of each single quantified pathway.
Clival exposure quantification (Figure 4A-B)40,41: •
Upper clivus: between the posterior clinoid processes and the axial plane passing through the sellar floor (almost corresponding to the dorsum sellae).
Middle clivus (midclivus): between the latter plane superiorly, carotid sulci bilaterally, and the
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•
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To assess clival exposure, 3 areas of the clivus were traced on the CT of each specimen as follows
axial plane passing through the sphenoidal floor inferiorly (in case of poorly pneumatized sphenoid sinuses, the axial plane passing through vidian nerves was adopted). Lower clivus: between the latter plane superiorly, the medial ends of hypoglossal canals
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•
bilaterally, and the foramen magnum inferiorly.
Three-dimensional (3D) coordinates recorded by the software were re-elaborated in real-time to obtain the measures of volumes and exposed areas. Volumes were expressed in cm3, while exposure of the aforementioned clival areas crossed by the “surgical pyramid” of each approach was
Statistical analysis
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expressed in percentages (Figure 4C).
Data were collected in Excel (Microsoft, Redmond, WA, USA) and analyzed with XLSTAT
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(Addinsoft, Paris, France). Shapiro-Wilk normality and Levene homoscedasticity tests were applied to all measured data. Mean or median of each sample was calculated, as appropriate. After verifying
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the non-normality and homoscedasticity of the samples, volumes, and areas of the analyzed approaches were compared with a Kruskal-Wallis test with Steel-Dwass-Critchlow-Fligner post-hoc test. Significance was set at p
