- Goodman Campbell Brain and Spine, Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, Indiana, USA
Aaron A. Cohen-Gadol
Goodman Campbell Brain and Spine, Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, Indiana, USA
DOI:10.4103/2152-7806.128918Copyright: © 2014 Ansari SF. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
How to cite this article: Ansari SF, Young RL, Bohnstedt BN, Cohen-Gadol AA. The extended supracerebellar transtentorial approach for resection of medial tentorial meningiomas. Surg Neurol Int 15-Mar-2014;5:35
How to cite this URL: Ansari SF, Young RL, Bohnstedt BN, Cohen-Gadol AA. The extended supracerebellar transtentorial approach for resection of medial tentorial meningiomas. Surg Neurol Int 15-Mar-2014;5:35. Available from: http://sni.wpengine.com/surgicalint_articles/test-4/
Background:The supracerebellar transtentorial (SCTT) approach has been established as a safe corridor to access the posteriomedial basal temporal region. Previous reports have demonstrated the efficacy of this route in the resection of intrinsic tumors and small arteriovenous malformations. Only one report in the English literature has described its use to resect a medial tentorial meningioma.
Methods:The authors discuss the relevant surgical anatomy of this approach and its advantages compared with more traditional routes, and illustrate its application to remove medial tentorial meningiomas through two operative cases with accompanying videos.
Results:In illustrative case one, the patient recovered from surgery with no deficits. All his preoperative symptoms had resolved at 3-month follow-up. At the 4-year follow-up, MRI did not demonstrate any growth of the residual tumor. In case two, gross total resection was achieved and the patient did not suffer any postoperative language or visual deficit. At 2-year follow-up, no tumor recurrence was present.
Conclusion:The SCTT approach has a potential to safely access extra-axial lesions located around the medial tentorial incisura. As demonstrated in these two cases, the approach merits consideration in patients with tentorial meningiomas as an alternative to more widely utilized skull base approaches and subtemporal routes.
The supracerebellar transtentorial (SCTT) approach to the mediobasal temporal region (MTR) has been previously described in the literature.[
Only one report[
The MTR is the portion of the temporal lobe contained within the following limits: Medially, the cavernous sinus and basal cisterns; anteriorly, the lesser wing of the sphenoid bone; laterally, the rhinal and colleratal sulci of the temporal lobe; and posteriorly the isthmus of the cingulate gyrus.[
Numerous important neurovascular structures exist in the MTR and tentorial incisura. The cerebral peduncles and midbrain tegmentum form the medial border of this space and the parahippocampal gyrus forms a curving lateral wall. The trochlear nerve (CN IV) passes through this region and is closely related to the tentorial free edge as it makes its way to the cavernous sinus. It usually reaches the free edge around the posterior portion of the cerebral peduncle. Preservation of CN IV is a key aspect of the transtentorial approach, and the early exposure and dissection afforded by this approach increases the chances for its preservation. Major arteries in the MTR include the anterior choroidal artery, PCA, and superior cerebellar artery (posterior portion), as well as M1 branches (in the anterior portion).[
The SCTT approach can be performed with the patient in the fully prone or park bench positions. Some describe the use of the sitting or semi-sitting position for optimal gravity-aided cerebellar retraction.[
A hockey-stick incision can be made in the midline or a linear incision in the paramedian positions, though the midline incision is likely to be associated with less postoperative pain.[
A dural incision is made with its base along the transverse sinus. Tentorial bridging veins draining the posterior cerebellar hemisphere are coagulated and cut to allow the cerebellum to fall away from the tentorium. Sacrifice of the posterior hemispheric bridging veins is safe, but compromise of the anterior vermian bridging veins may potentially lead to cerebellar venous infarction.[
Gradual release of the CSF will allow mobilization of the cerebellar hemisphere inferiorly and generous exposure of the tentorium. Medial tentorial meningiomas protrude along the tentorial incisura into the posterior fossa and compress the posterior brainstem and surrounding neurovascular structures [
Medial tentorial meningiomas protrude along the tentorial incisura into the posterior fossa and compress the posterior brainstem and surrounding neurovascular structures. A tentorial incision along the red line will place the trochlear nerve at risk of injury and should be avoided. The black line defines the route of correct tentorial incision (a). The early exposure of these structures provided by the SCTT approach allows for their protection by microdissection away from the tumor before significant tumor debulking is performed and the surgical field is obscured by bleeding. Two retraction sutures are placed in the tentorium just anterior to the transverse sinus to mobilize this venous sinus superiorly and expand the operative corridor. These retraction sutures may be attached to the skin to maintain their tension (b). A generous portion of the tentorium is then incised from the petrous ridge to the midline while identifying and preserving the trochlear nerve along the entire anterior edge of the tentorium (c). The tumor can then be debulked and removed (d-g)
The above described sectioning of the tentorium will further devascularize the tumor and allow a relatively bloodless field to debulk the tumor and microsurgically mobilize it from the surrounding cortex and distal branches of the PCA and medial veins [Figure
A 43-year-old male presented with several months of progressive dysarthria and gait imbalance. Imaging work-up including magnetic resonance imaging (MRI) demonstrated a large left medial tentorial meningioma extending along the posteromedial aspect of the temporal lobe and medial aspect of the brainstem, causing significant mass effect on these structures with early signs of hydrocephalus [
MRI demonstrated a large left medial tentorial meningioma extending along the posteromedial aspect of the temporal lobe and medial aspect of the brainstem, causing significant mass effect on these structures with early signs of hydrocephalus [(a) sagittal; (b and c) axial; (d) coronal T1 enhanced MRIs]. Large flow-voids within the tumor emphasized its rich vascularity [(e) axial T2 MRI]
Following modest embolization of the tumor's large feeding meningeal vessels, resection was attempted. A staged procedure for the infratentorial and supratentorial components of this tumor was considered. We decided that a SCTT route would avoid a staged operation and minimize the risk to the dominant temporal lobe. Using a paramedian incision [
Using the technique mentioned above, we incised a section of the tentorium affected by the tumor and removed the supratentorial extension of the tumor as well as the piece attached to the petrous apex. This operative corridor allowed microsurgical dissection of the tumor wall away from the cortex and adjacent distal PCA branches. A small portion of the tumor lateral and superior to the petrous apex was left behind due to its inaccessibility [
A 33-year-old female presented with severe headaches and an episode of receptive aphasia. MRI evaluation revealed a left medial tentorial meningioma associated with cerebral edema [
Through a left hockey-stick incision, the SCTT route was used to remove the tumor [
Although the SCTT approach has been described in the neurosurgical literature, there is only one report of its use to remove a meningioma.[
A number of techniques can be used to access the medial posterior temporal region through lateral and posterior approaches.[
Subtemporal approaches to the medial tentorium place the functional language cortex and optic radiations at less risk from direct damage, but these approaches are associated with language dysfunction as a result of excessive and/or prolonged temporal lobe retraction. Furthermore, any injury to the anastomotic vein of Labbé can be problematic.[
With our patients, the SCTT approach allowed adequate access to the tumor while minimizing morbidity associated with the above-mentioned more traditional approaches. In case one, the SCTT route avoided a staged operation and a more extensive skull base approach (i.e., petrosectomy). In this case, opening of the dura superior and inferior to the tentorium could have assisted with more tumor exposure and control of bleeding. In case two, the position of the tumor precluded access through more conventional approaches, such as subtemporal or transtemporal corridors, without facing a significant risk of postoperative deficit. In addition, early access to the base of the tumor allowed early tumor devascularization while minimizing blood loss and providing a clear field for microsurgical dissection of the important cerebrovascular structures (posterior brainstem and trochlear nerve) along the tentorial incisura. Through this approach, the instruments’ working angles are enhanced, although their working distance is increased.
Tentorial meningiomas are rare tumors, accounting for 2-3% of all intracranial meningiomas,[
The SCTT approach provides a longer working distance for the surgeon and is more technically demanding. In addition, incisions within the tentorium can be challenging due to the high vascularity of the region, especially increased by the presence of the tumor. The dome of the tumor is accessed at the end of the operation and is the “blind spot” for the operator. This fact may lead to an injury to vessels adherent to the dome of the tumor. Cerebellar retraction should be minimized to avoid retraction injury. The anterolateral extent of exposure is marked by the petrous bone and petrous bone drilling may lead to additional exposure.
The SCTT approach has a potential to safely access extra-axial lesions located around the medial tentorial incisura. As demonstrated in these two cases, the approach merits consideration in patients with tentorial meningiomas as an alternative to more widely used skull base approaches and subtemporal routes. As cited earlier, early exposure to the venous structures is seen by some as a blessing and by others as a shortcoming—careful review of the patient's preoperative venous imaging is critical to determine if this approach will be safe. In particular, the surgeon must assess whether the tumor is displacing the vasculature in such a way that dissection of the SCTT is beneficial or potentially more risky. Decisions regarding operative approach should be individualized based on a given patient's lesion, overall medical condition, and the skill and preference of the surgeon.
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