-lying basilar apex. The classic approach to basilar apex aneurysms has been subtemporal, pterional, or variants thereof. 3 , 4 , 6–8 , 10 , 11 , 13 , 17 , 18 , 21 , 24 These approaches provide widened superficial exposure but cannot enlarge the area of exposure near the lesion. These avenues present drawbacks to surgeons treating low-lying basilar apex aneurysms obscured by the dorsum sellae or clivus. More “dramatic” skull base approaches to access such aneurysms have been described, including anterior petrosectomy and the transcavernous approach. 1 , 2 , 5 , 12 , 16
Eberval Gadelha Figueiredo, Joseph M. Zabramski, Pushpa Deshmukh, Neil R. Crawford, Mark C. Preul and Robert F. Spetzler
Ali F. Krisht
The region in the upper anterior third of the posterior fossa is a surgically hidden, narrow corridor between the petroclival surface anteriorly and the surface of the brainstem posteriorly. Although several approaches have been described to help surgeons reach this region, few of them enable practitioners to reach the different corners of the area and provide as wide a view as the one achieved using the transcavernous route.
A transcavernous approach was used in 91 cases (50 complex upper basilar artery [BA] aneurysms, 30 upper petroclival junction meningiomas, five trigeminal nerve schwannomas, three upper clival chordomas, and three anterior pontine lesions) involving the anterior upper third of the posterior fossa. The approach uses the pretemporal route with exposure of the lateral wall of the cavernous sinus. It entails removal of the anterior clinoid process. The posterior clinoid process is also removed when necessary. The approach leads to the upper basilar region. It is widened inferiorly to expose the anterior aspect by removal of the posterior clinoid process and the petroclival osseous and dural elements. Its lateral extension exposes the region of the Meckel cave and it can be widened by removal of the petrous apex.
Seventy patients experienced new transient mild cranial neuropathies, 67 of whom recovered fully. Surgically related ischemic morbidities occurred in three patients with BA aneurysms (one small medial thalamic infarct, ataxia due to superior cerebellar artery ischemia, and distal middle cerebral artery embolus in a patient with atrial fibrillation in whom anticoagulation therapy was stopped). All the neuropathies in patients with BA aneurysms were oculomotor and recovery was the rule in all of them. Three new permanent cranial neuropathies occurred in the patients with meningiomas. In seven patients with preoperative neuropathy, two had partial improvement. Five patients with atypical meningiomas were treated with postoperative radiation therapy. Progression occurred later in four patients who were treated with gamma knife surgery. There were no surgery-related deaths. More than 1 year of follow-up data were available in 85 patients, and 94% of those patients were in an active and functional state (Glasgow Outcome Scale scores of 4 and 5).
The safety achieved with the transcavernous route allows surgeons to achieve wide exposures to lesions involving the anterior upper third of the posterior fossa. It is an approach that should be mastered by every neurosurgeon dealing with cranial lesions.
Stephen L. Nutik
obtained by transcavernous removal of the posterior clinoid process and ipsilateral dorsum sellae. In two patients (Cases 2 and 3), a more lateral approach was attempted before using the transcavernous approach; however, this did not help the exposure of the lesion. The lateral approach was made by section of the bridging temporal veins and posterolateral retraction of the temporal lobe as well as subpial resection of the uncus in Case 2. There were various reasons why a more proximal exposure of these aneurysms was needed. In Cases 1, 2, and 6, additional space was
Ming-Ying Lan and Wei-Hsin Wang
This is a 37-year-old woman who presented with weight gain, a moon-shaped face, and muscle weakness for 4 months. Cushing’s disease was confirmed after a series of diagnostic tests. MRI demonstrated a pituitary macroadenoma with right cavernous sinus invasion and encasement of the right ICA. An endoscopic endonasal approach was performed, and gross-total resection could be achieved without injury of the cranial nerves. The Cushing’s syndrome improved gradually after the surgery. Histopathology revealed a corticotroph adenoma. In this surgical video, we demonstrate the strategies of tumor resection according to a surgical anatomy-based classification of the cavernous sinus from an endonasal perspective.
The video can be found here: https://youtu.be/aNXFRdGfjpI.
Mohamed A. Labib, Leandro Borba Moreira, Xiaochun Zhao, Sirin Gandhi, Claudio Cavallo, Ali Tayebi Meybodi, A. Samy Youssef, Andrew S. Little, Peter Nakaji, Mark C. Preul and Michael T. Lawton
extended bifrontal approaches challenging. 3) The upper retroclival region itself is a narrow crossroad of several neurovascular structures. Originally described by Dolenc et al. 6 and then modified by others, 5 , 6 , 13 , 14 , 19 , 23 the pretemporal transcavernous approach (PTA) has become an important gateway to access deep skull base lesions. The extradural nature of this approach makes it particularly attractive. Nonetheless, the steep learning curve, negative connotations of the name “transcavernous,” and emergence of endovascular therapy and radiosurgery as
Stephen L. Nutik
The author describes a surgical procedure in which pterional craniotomy is performed via a transcavernous approach to treat low-lying distal basilar artery (BA) aneurysms. This intradural procedure is compared with the extradural procedure described by Dolenc, et al.
The addition of a transcavernous exposure to the standard pterional intradural transsylvian approach allows a lower exposure of the distal BA behind the dorsum sellae. The technical steps involved in this procedure are as follows: 1) removal of the anterior clinoid process; 2) entry into the cavernous sinus medial to the third nerve; 3) packing of the venous channels of the cavernous sinus lying between the carotid artery and the pituitary gland to open this space; 4) removal of the posterior clinoid process and the portion of the dorsum sellae that is exposed from within the cavernous sinus; and 5) removal of the exposed dura mater to obtain additional exposure of the perimesencephalic cistern. Eight cases of aneurysms of the distal BA are presented to illustrate how this approach can help in their surgical treatment.
Using the standard pterional approach, these distal BA aneurysms were found to be either too low relative to the posterior clinoid process for adequate exposure or there was insufficient room for temporary clipping of the BA proximal to the lesion. The addition of a transcavernous exposure eliminated these technical problems and aneurysm clipping could be accomplished in each case.
Ali Tayebi Meybodi, Sirin Gandhi, Justin Mascitelli, Baran Bozkurt, Gyang Bot, Mark C. Preul and Michael T. Lawton
exposure gained through the OTT. First, a transcavernous approach (TcA) was performed by the following steps to increase the mobility of the third cranial nerve: 2 , 31 1) intradural anterior clinoidectomy; 2) opening the roof of the cavernous sinus medial to the oculomotor nerve to release the cavernous segment of the oculomotor nerve and anterior genu of the cavernous carotid artery; and 3) posterior clinoidectomy. The above-mentioned measurements were repeated (except the length of the exposed tentorium and oculomotor nerve) after TcA. Next, the temporal lobe uncus
Amitabha Chanda and Anil Nanda
approach described by Heros and Lee. 10 These authors used posterior retraction of the temporal pole, which is tolerated much better than elevation of the temporal lobe. 17, 22, 23 In the orbitozygomatic transcavernous approach, the type of temporal lobe retraction that is selected is usually posterior retraction of temporal pole. Although Heros and Lee 10 have combined the advantages of these two approaches, the approach itself is not suitable for BA bifurcation aneurysms that are located high or low with respect to the norm. These authors have admitted the
Juan C. Fernandez-Miranda, Paul A. Gardner, Milton M. Rastelli Jr., Maria Peris-Celda, Maria Koutourousiou, David Peace, Carl H. Snyderman and Albert L. Rhoton Jr.
layer that continues medial to the posterior petroclinoid ligament covers the dorsum sellae and forms the meningeal layer that lines the drainage of the basilar plexus into the cavernous sinus ( Fig. 1 ). Understanding the dural layering of the anterior (sphenoidal) and medial (sellar) walls of the cavernous sinus is crucial to obtaining surgical access to the posterior clinoid via a transsphenoidal transcavernous approach. As it is well known, the 2 layers of dura mater—meningeal or inner and periosteal or outer—that cover the anterior wall of the pituitary gland
Huy Q. Truong, Hamid Borghei-Razavi, Edinson Najera, Ana Carolina Igami Nakassa, Eric W. Wang, Carl H. Snyderman, Paul A. Gardner and Juan C. Fernandez-Miranda
well guarded laterally by the ICA, the IHA was rarely a surgical consideration until the endoscopic endonasal approach brought light via ventral access to the cavernous sinus. The endoscopic endonasal transcavernous approach with the interdural pituitary gland transposition technique provides excellent surgical access to the posterior clinoid and lateral interpeduncular cistern. 3 , 4 Prior to performing a posterior clinoidectomy, elective coagulation and transection of the IHA is recommended to prevent uncontrolled tearing of the artery or its avulsion from the