Microsurgical Anatomy of the Endoscopy-Assisted Retrosigmoid Intradural Suprameatal Approach to the Meckel's Cave

2021 ◽  
Author(s):  
Yuanzhi Xu ◽  
Benjamin K Hendricks ◽  
Maximiliano Alberto Nunez ◽  
Ahmed Mohyeldin ◽  
Juan C Fernandez-Miranda ◽  
...  

Abstract BACKGROUND Understanding the microsurgical anatomical features of the endoscopy-assisted retrosigmoid intradural suprameatal approach (RISA) is critical for surgeons treating petroclival tumors or lesions in the cerebellopontine region that extend into Meckel's cave. OBJECTIVE To evaluate increased exposure for Meckel's cave in the RISA and assess the surgical landmarks for this approach. METHODS A standard retrosigmoid craniotomy to the cerebellopontine region was performed in 4 cadaveric specimens (8 hemispheres) with microscope-assisted endoscopy. The length and depth of the drilling region from the suprameatal tubercle to the petrous apex were analyzed. After opening Meckel's cave and mobilizing the trigeminal root completely, the landmarks for this approach were investigated. RESULTS The endoscopy-assisted RISA facilitates mobilization of the trigeminal root and enhances surgical exposure in the region of Meckel's cave and the petrous apex with increases of 10.1 ± 1.3 mm in depth, 21.4 ± 3.2 mm in length, and 6.4 ± 0.6 mm in height. The posterior and superior semicircular canals, internal auditory canal, superior petrous sinus, and internal carotid artery (petrous segment) served as important landmarks for this approach. One case illustration is presented to describe the application of this approach. CONCLUSION The RISA is suitable mainly for lesions in the posterior fossa that extend into Meckel's cave. The endoscopy-assisted reach optimizes accessibility to the petrous apex region, obviates the need for extensive drilling, and decreases the risk of internal carotid artery injury. Better realization and recognition of microsurgical landmarks and parameters of this approach are crucial for successful outcomes.

2006 ◽  
Vol 59 (suppl_1) ◽  
pp. ONS-1-ONS-6 ◽  
Author(s):  
Amitabha Chanda ◽  
Anil Nanda

Abstract OBJECTIVE: To assess the advantages and disadvantages of the retrosigmoid intradural suprameatal approach by studying the microsurgical anatomy. This study was performed primarily to assess the advantages of the retrosigmoid intradural suprameatal approach by measuring the amount of increased exposure it provides for lesions of the cerebellopontine and petroclival region as well as to identify the disadvantages of the approach. METHODS: Twenty sides of 10 cadaver heads (embalmed and injected) were dissected under ×3 to ×40 magnification. A standard retrosigmoid craniotomy was made. The cerebellopontine cistern was entered to expose the neurovascular structures, and the internal auditory canal was opened by drilling the margin of the internal auditory meatus. After this, the suprameatal tubercle was drilled, followed by additional drilling to resect the petrous apex. The trigeminal root was mobilized completely after opening Meckel's cave. During drilling, care was taken to preserve the posterior and superior semicircular canals, petrosal sinus, and the internal carotid artery. RESULTS: The approach enhanced the exposure of the cerebellopontine cistern and Meckel's cave. There was an additional exposure of 10.7 ± 1.16 mm length of trigeminal nerve on the right side and an additional 10.7 ± 1.25 mm on the left. This helped to mobilize and further retract the trigeminal root. Although it facilitated the view of the neurovascular structures medial to the internal acoustic meatus, the depth of exposure did not vary much from a traditional retrosigmoid approach nor did it increase the angle of exposure or the visualization of the clivus and more medially located structures. CONCLUSION: This approach is suitable for lesions mainly in the posterior fossa with some extension into the middle fossa in the anterolateral direction. The key benefits of this approach are the length of trigeminal nerve exposure and the subsequent mobilization that improves visualization of the structures medial to the internal auditory canal, to the petrous apex, Meckel's cave, and the posterior end of the cavernous sinus.


2017 ◽  
Vol 14 (4) ◽  
pp. 432-440 ◽  
Author(s):  
Eleonora Marcati ◽  
Norberto Andaluz ◽  
Sebastien C Froelich ◽  
Lee A Zimmer ◽  
James L Leach ◽  
...  

Abstract BACKGROUND Although the term paraclival carotid pervades recent skull base literature, no clear consensus exists regarding boundaries or anatomical segments. OBJECTIVE To reconcile various internal carotid artery (ICA) nomenclatures for transcranial and endoscopic-endonasal perspectives, we reexamined the transition between lacerum (C3) and cavernous (C4) segments using a C1-C7 segments schema. In this cadaveric study, we obtained a 360°-circumferential view integrating histological, microsurgical, endoscopic, and neuroradiological analyses of this C3-C4 region and identified a distinct transitional segment. METHODS In 13 adult, silicone-injected, formalin-fixed cadaveric heads (26 sides), transcranial-extradural-subtemporal and endoscopic-endonasal CT­guided dissections were performed. A quadrilateral area was noted medial to Meckel's cave between cranial nerve VI, anterolateral and posterolateral borders of the lateral-paratrigeminal aspect of the precavernous ICA, and posterior longitudinal ligament. Endoscopically, a medial-paraclival aspect was defined. Anatomical correlations were made with histological and neuroradiological slides. RESULTS We identified a distinct precavernous C3-C4 transitional segment. In 18 (69%) specimens, venous channels were absent at the quadrilateral area, on the paratrigeminal border of the precavernous ICA. A trigeminal membrane, seen consistently on the superior border of V2, defined the lateral aspect of the cavernous sinus floor. The medial aspect of the precavernous ICA corresponded with the paraclival ICA. CONCLUSION Our study revealing the juncture of 2 complementary borders of the ICA, endoscopic endonasal (paraclival) and transcranial (paratrigeminal), reconciles various nomenclature. A precavernous segment may clarify controversies about the paraclival ICA and support the concept of a “safe door” for lesions involving Meckel's cave, cavernous sinus, and petrous apex.


2021 ◽  
Author(s):  
Wei-Hsin Wang ◽  
Ming-Ying Lan ◽  
Carl H Snyderman ◽  
Paul A Gardner

Abstract This 59-yr-old man presented with headache, dizziness, diplopia, and right-side hearing impairment for years. The objective degree of hearing impairment was not available. Magnetic resonance imaging (MRI) showed a right petrous apex lesion centered behind the right petrous internal carotid artery and extending lateral to the medial aspect of the right internal auditory canal. A combined endoscopic endonasal and left contralateral transmaxillary (CTM) approach was performed, and gross-total resection was achieved. Peeling the cyst wall from the dura resulted in minor weeping. It was covered with a left-sided, vascularized nasoseptal flap. His dizziness and diplopia improved immediately after the surgery. Histopathology revealed an epidermoid cyst. In this surgical video, we demonstrate the key steps of the CTM approach for access to the petrous apex posterior to the petrous internal carotid artery (ICA).  The patient gave informed consent for surgery and video recording.


Author(s):  
Walid Elshamy ◽  
Burcak Soylemez ◽  
Sima Sayyahmelli ◽  
Nese Keser ◽  
Mustafa K. Baskaya

AbstractChondrosarcomas are one of the major malignant neoplasms which occur at the skull base. These tumors are locally invasive. Gross total resection of chondrosarcomas is associated with longer progression-free survival rates. The patient is a 55-year-old man with a history of dysphagia, left eye dryness, hearing loss, and left-sided facial pain. Magnetic resonance imaging (MRI) showed a giant heterogeneously enhancing left-sided skull base mass within the cavernous sinus and the petrous apex with extension into the sphenoid bone, clivus, and the cerebellopontine angle, with associated displacement of the brainstem (Fig. 1). An endoscopic endonasal biopsy revealed a grade-II chondrosarcoma. The patient was then referred for surgical resection. Computed tomography (CT) scan and CT angiogram of the head and neck showed a left-sided skull base mass, partial destruction of the petrous apex, and complete or near-complete occlusion of the left internal carotid artery. Digital subtraction angiography confirmed complete occlusion of the left internal carotid artery with cortical, vertebrobasilar, and leptomeningeal collateral development. The decision was made to proceed with a left-sided transcavernous approach with possible petrous apex drilling. During surgery, minimal petrous apex drilling was necessary due to autopetrosectomy by the tumor. Endoscopy was used to assist achieving gross total resection (Fig. 2). Surgery and postoperative course were uneventful. MRI confirmed gross total resection of the tumor. The histopathology was a grade-II chondrosarcoma. The patient received proton therapy and continues to do well without recurrence at 4-year follow-up. This video demonstrates steps of the combined microsurgical skull base approaches for resection of these challenging tumors.The link to the video can be found at: https://youtu.be/WlmCP_-i57s.


Neurosurgery ◽  
1990 ◽  
Vol 26 (3) ◽  
pp. 472-479 ◽  
Author(s):  
Slobodan V. Marinkovié ◽  
Milan M. Milisavljevié ◽  
Zorica D. Marinkovié

Abstract The perforating branches of the internal carotid artery (ICA) were examined in 30 forebrain hemispheres. These branches were present in all the cases studied, and varied from 1 to 6 in number (mean, 3.1). Their diameters ranged from 70 to 470 Mm (mean, 243 Mm). The perforating branches arose from the choroidal segment of the ICA, that is, from its caudal surface (52.3%), caudolateral surface (34.1%), or caudomedial surface (13.6%). They rarely originated from the bifurcation point of the ICA (10%). The distance of the remaining 90% of the perforators from the summit of the ICA measured between 0.6 and 4.6 mm. The perforating branches most often originated as individual vessels, and less frequently from a common stem with another vessel or by sharing the same origin site with another perforator or with the anterior choroidal artery. The bifurcation of the ICA, which is a frequent site for cerebral aneurysms, is surrounded by many perforating branches. Hence, great care must be taken to avoid damage to these important vessels during operations in that region.


Author(s):  
K C Prasad ◽  
A Gupta ◽  
G Induvarsha ◽  
P K Anjali ◽  
V Vyshnavi

2008 ◽  
Vol 63 (suppl_4) ◽  
pp. ONS210-ONS239 ◽  
Author(s):  
Shigeyuki Osawa ◽  
Albert L. Rhoton ◽  
Necmettin Tanriover ◽  
Satoru Shimizu ◽  
Kiyotaka Fujii

Abstract Objective: The petrous segment of the internal carotid artery has been exposed in the transpetrosal, subtemporal, infratemporal, transnasal, transmaxillary, transfacial, and a variety of transcranial approaches. The objective of the current study was to examine anatomic features of the petrous carotid and its branches as related to the variety of approaches currently being used for its exposure. Methods: Twenty middle fossae from adult cadaveric specimens were examined using magnification of ×3 to ×40 after injection of the arteries and veins with colored silicone. Results: The petrous carotid extends from the entrance into the carotid canal of the petrous part of the temporal bone to its termination at the level of the petrolingual ligament laterally and the lateral wall of the sphenoid sinus medially. The petrous carotid from caudal to rostral was divided into 5 segments: posterior vertical, posterior genu, horizontal, anterior genu, and anterior vertical. Fourteen (70%) of the 20 petrous carotids had branches. The branch that arose from the petrous carotid was either a vidian or periosteal artery or a common trunk that gave rise to both a vidian and 1 or more periosteal arteries. The most frequent branch was a periosteal artery. Conclusion: An understanding of the complex relationships of the petrous carotid provides the basis for surgically accessing any 1 or more of its 5 segments.


Neurosurgery ◽  
2002 ◽  
Vol 50 (4) ◽  
pp. 829-837 ◽  
Author(s):  
Mehmet Faik Ozveren ◽  
Koichi Uchida ◽  
Sadakazu Aiso ◽  
Takeshi Kawase

Abstract OBJECTIVE: The goals of this investigation were to perform a detailed analysis of petroclival microanatomic features, to investigate the course of the abducens nerve in the petroclival region, and to identify potential causes of injury to neurovascular structures when anterior transpetrosal or transvenous endovascular approaches are used to treat pathological lesions in the petroclival region. METHODS: Petroclival microanatomic features were studied bilaterally in seven cadaveric head specimens, which were injected with colored silicone before microdissection. Another cadaveric head was used for histological section analyses. RESULTS: A lateral or medial location of the abducens nerve dural entrance porus, relative to the midline, was correlated with the course and angulation of the abducens nerve in the petroclival region. The angulation of the abducens nerve was greater and the nerve was closer to the petrous ridge in the lateral type, compared with the medial type. The abducens nerve exhibited three changes in direction, which represented the angulations in the petroclival region, at the dural entrance porus, the petrous apex, and the lateral wall of the internal carotid artery. The abducens nerve was covered by the dural sleeve and the arachnoid membrane, which became attenuated between the second and third angulation points. The abducens nerve was anastomosed with the sympathetic plexus and fixed by connective tissue extensions to the lateral wall of the internal carotid artery and the medial wall of Meckel's cave at the third angulation point. There were two types of trabeculations inside the sinuses around the petroclival region (tough and delicate). CONCLUSION: The petroclival part of the abducens nerve was protected in a dural sleeve accompanied by the arachnoid membrane. Therefore, the risk of abducens nerve injury during petrous apex resection via the anterior transpetrosal approach, with the use of the transvenous route through the inferior petrosal sinus to the cavernous sinus, should be lower than expected. The presence of two anatomic variations in the course of the abducens nerve, in addition to findings regarding nerve angulation and tethering points, may explain the relationships between adjacent structures and the susceptibility to nerve injury with either surgical or endovascular approaches. Venous anatomic variations may account for previously reported cases of subarachnoid hemorrhage with the endovascular approach.


2007 ◽  
Vol 61 (suppl_3) ◽  
pp. ONS-E52-ONS-E52 ◽  
Author(s):  
Niklaus Krayenbühl ◽  
Ahmad Hafez ◽  
Juha A. Hernesniemi ◽  
Ali F. Krisht

Abstract Objective: Improved understanding of the microsurgical anatomy of the cranial base region has made surgery in and through the cavernous sinus safer. However, continuous venous oozing that occurs during cavernous sinus surgery can cause significant blood loss and poor visualization. We describe a technique that will help minimize cavernous sinus bleeding and improve the safety of the surgical steps. Methods: The lateral wall of the cavernous sinus is exposed. Cavernous sinus access windows between the V1 and V2 branches of the trigeminal nerve and posterior to the clinoidal internal carotid artery are used to inject fibrin glue into the different cavernous sinus compartments. Postoperative follow-up cerebral angiography in basilar apex aneurysms clipped using the transcavernous approach were evaluated for cavernous sinus patency during the venous phase. Results: Fibrin glue injection between V1 and V2 obliterated the lateral cavernous sinus compartment. Fibrin glue injection posterior to the clinoidal segment of the internal carotid artery obliterated the medial compartment of the cavernous sinus. These steps were used in 217 surgical procedures (95 benign and 9 malignant neoplastic lesions; 113 aneurysms). There were no significant clinical side effects. Follow-up angiographic controls of basilar aneurysms operated on via the transcavernous approach consistently showed the reestablishment of flow within the cavernous sinus as early as 2 to 3 months postoperatively. Conclusion: Presently, the use of hemostatic agents and the better understanding of the microsurgical anatomy of the cranial base and cavernous sinus enable us to tame the cavernous sinus and operate in and around it with a high degree of safety.


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