Anterior Petrosectomy Research Articles

Comparison between the Anterior Petrosectomy and the Expanded Endoscopic Endonasal Approach. Interest in Skull Base Tumors Surgical Management

Comparison between the Anterior Petrosectomy and the Expanded Endoscopic Endonasal Approach. Interest in Skull Base Tumors Surgical Management

Which Routes for Petroclival Tumors? An Anatomic Comparison between the Anterior Petrosectomy and the Expanded Endoscopic Endonasal Approach

Which Routes for Petroclival Tumors? An Anatomic Comparison between the Anterior Petrosectomy and the Expanded Endoscopic Endonasal Approach

Epi- and Subdural Anterior Petrosal Approach to Preserve Venous Flow of Sphenobasal Veins

Objective: Anterior transpetrosal approach is well known as effective surgical procedure to the lesions at petroclival area. However, wide epidural exposure of the petrous apex might obstacle the venous flow of sphenobasal veins which might cause venous complications at the area of Sylvian veins. Recently, we developed a new technique named as epi- and subdural anterior petrosal approach to avoid venous complications and to minimize the surgical procedure. This study aims to demonstrate our technique in detail and present the effect of the procedure. Methods: Since January, 2012 our new technique is applied to 10 patients with petroclival meningioma or pontine cavernoma. The key step of our technique is limited epidural exposure of petrous bone, which can preserve venous flow around the foramen ovale. Before opening the dura mater, petrous drilling was limited just along the superior petrosal sinus (SPS) to ligate the SPS. Additional petrosectomy was performed after dural opening and cutting the SPS and tentorium. This subdural procedure can offer wider surgical corridor to petrous apex and restrict the epidural exposure of the middle fossa, which can preserve the venous flow of spehnobasal sinus and shorten the surgical time of petrosectomy. Result: All 10 pathologies were successfully removed without any venous complications. In addition, anatomical landmarks for anterior petrosectomy were easily identified in subdural procedure compared with in original epidural procedure.

Tumor-Induced Surgical Anatomical Variations of Cranial Nerves in Anterior Petrosectomy for Petroclival Tumors

Tumor-Induced Surgical Anatomical Variations of Cranial Nerves in Anterior Petrosectomy for Petroclival Tumors

Epidural Anterior Petrosectomy with Subdural Visualization of Sphenobasal Vein via the Anterior Transpetrosal Approach

The drainage of the superficial middle cerebral vein (SMCV) is classified into four subtypes. The sphenobasal vein (SBV) drains from the SMCV to the pterygoid venous plexus at the temporal skull base. Epidural procedures in the standard anterior transpetrosal approach (ATPA) may damage the route of the SBV. We report a case in which modified surgical procedures via the ATPA were used to preserve the SBV. A 45-year-old male complained of right facial pain. Magnetic resonance (MR) images revealed a right cerebellopontine tumor suggestive of an epidermoid cyst. Right carotid angiography revealed that the SMCV drained into the pterygoid venous plexus via the SBV. The convexity dura mater of the temporal lobe was cut and the anterior part of the temporal lobe was retracted subdurally. The basal dura of the temporal lobe posterior to the SBV vein was visualized and cut subdurally. The posterior part of the temporal lobe was retracted epidurally. After dissecting, the dura mater medial to the greater petrosal nerve and to the edge of the petrous apex, the petrous apex was exposed and drilled out without injuring the SBV. The superior petrous sinus and the tentorium were cut. The tumor was compressed at the root exit zone of the trigeminal nerve. The tumor was removed grossly and totally. The modified ATPA (epidural anterior petrosectomy with subdural visualization of sphenobasal vein) is effective to preserve the SBV.

Anterior Clinoidectomy to Anterior Petrosectomy through Modified Subtemporal Pterional Keyhole Approach

Anterior Clinoidectomy to Anterior Petrosectomy through Modified Subtemporal Pterional Keyhole Approach

Role of Surgery in Brainstem Metastasis

Objective: To evaluate surgical management of a single brainstem metastasis. Study Design: Case presentation. Patient and Methods: A 66 years old right-handed male with new onset of slurred speech, imbalance, dizziness, right facial drop, dysmetria, and nystagmus. MRI showed left pons hematoma with irregular enhancement. MRA and angiogram were negative for aneurysm, or AVM. A CT chest showed a single 2cm right lung lesion. Initially improved with steroids but worsened 2weeks after discharge, and his repeated MRI showed enlargement of the pons hemorrhage (2.8cm major diameter) with diagnosis of cavernoma versus hemorrhagic neoplasm, and no signs of hydrocephalus. Results: Performed left anterior petrosectomy (Kawase approach), left ventrolateral infratrigeminal pontine hematoma and cyst fluid evacuation, and lesion biopsy under stereotactic guidance, electrophysiology monitoring (facial nerve, brainstem auditory evoked potentials, and somatosensory evoked potentials), and lumbar drain placement on September 27, 2013. Patient stayed in ICU for4days until lumbar drain removal, discharged to rehab postoperative day6. He experienced a gradual improvement on his balance and face drop. Pathology reported metastatic poorly differentiated adenocarcinoma and received WBRT with a total of 3,000cGy in 10 fractions. Given his decreased size of the lesion and edema, a boost of stereotactic radiosurgery was performed on December 19, 2013 with a total of 12Gy to the margin of the tumor, minimizing brainstem dose. Conclusion: Brainstem metastasis usually carries a poor prognosis, and surgical attempts are avoided due to high morbidity and mortality. In some selective cases of brainstem metastasis, surgical decompression can be safely performed decreasing irreversible damage due to local mass effect.

Partial Anterior Petrosectomy: Old Wine, New Bottle

Transpetrosal approaches that involve resection of various portions of the petrous bone to gain access to lesions in the petrous apex, brainstem, and tentorial incisura have existed for many years. With the rapid advances in endovascular neurosurgery and improved morbidity and mortality profile of these techniques, surgery for newly diagnosed posterior circulation aneurysms has taken a back seat. Also, the profile of aneurysms that are being referred for surgical clipping has changed, and an increasing number of complex aneurysms is being clipped. These complex aneurysms include giant aneurysms, aneurysms that develop after coiling, and aneurysms with contraindications to endovascular treatment. Because the number of aneurysms being surgically clipped has decreased, neurosurgeons-in-training have less exposure to their surgical management. In the study by Fukuda et al., the authors describe the partial anterior petrosectomy (P-ATP) technique in cadaver heads and its application in the surgical management of a patient with ruptured upper basilar trunk aneurysm. The P-ATP involves removal of the bone medial to the internal carotid artery with anterior translocation of the mandibular division of the trigeminal nerve (cranial

Anterior inferior petrosectomy: defining the role of endonasal endoscopic techniques for petrous apex approaches

Historically, surgery to the petrous apex has been addressed via craniotomy and open microscopic anterior petrosectomy (OAP). However, with the popularization of endoscopic approaches, the petrous apex can further be approached endonasally by way of an endoscopic endonasal anterior petrosectomy (EAP). Endonasal anterior petrosectomy is a relatively new procedure and has not been compared anatomically with OAP. The authors hypothesized that the EAP and OAP techniques approach different portions of the petrous apex and therefore may have different applications. Four cadaveric heads were used. An OAP was performed on one side and an EAP was performed on the contralateral side; the limits of bony resection were defined. The extent of bony resection was then evaluated using predissection and postdissection thin-slice CT scans. The comparative resection was then reconstructed using 3D modeling on Brainlab workstations. The average resection volumes for EAP and OAP were 0.297 cm(3) and 0.649 cm(3), respectively, representing a comparative percentage of 46% (EAP/OAP). An EAP and OAP achieved resection of 29% and 64% of the total petrous apex volume, respectively. Indeed, EAP addressed the inferior portion of the petrous apex located adjacent to the petroclival suture more completely than OAP, where 45% of the bone overlying the petroclival suture (petroclival angle to the jugular foramen) was resected with the EAP, while 0% was resected with the OAP. In anatomically normal cadavers, OAP achieved nearly a 50% larger volumetric resection than EAP. Furthermore, while OAP appears to completely address the superior portion of the petrous apex, EAP appears to have a niche in approaches to lesions in the inferior petrous apex. Given these results, the authors propose that OAP be redefined as the "superior anterior petrosectomy," while EAP be referred to as the "inferior anterior petrosectomy," which more clearly defines the role of each approach in anterior petrosectomy.

Volumetry and analysis of anatomical variants of the anterior portion of the petrous apex outlined by the kawase triangle using computed tomography.

Background Anterior petrosectomy has become an increasingly used approach for petroclival lesions. This study measures the volume and the anatomical variants of the anterior portion of the petrous apex outlined by the Kawase triangle using computed tomography (CT). Methods This was a transversal retrospective study. We assessed the anterior petrous apex portion outlined by the Kawase triangle in consecutive patients > 18 years of age from CT scans of temporal bone stored in an archive system. The volumetry was performed on a workstation. Results A total of 154 petrosal apex were analyzed in 77 patients (36 men). The average volume of the region outlined by the Kawase triangle was 1.89 ± 0.52 cm(3). The volume average in men was 2.01 ± 0.58 cm(3), and the average in women was 1.79 ± 0.41 cm(3). Intra- and interobserver agreement were both excellent, and there was little variance. Nineteen petrous apex demonstrated anatomical variations. In 18 cases it was pneumatized, and in one case a vascular or nerve-like structure was identified, a report we did not find in the literature. Conclusion The volumetry of the petrous apex anterior portion outlined by the Kawase triangle can be made by CT with excellent intra- and interobserver agreement and reproducibility. There are anatomical variants in this region that are relevant to surgery.

Quantitative Analysis of “Kawase's Triangle” versus “Modified Anterior Petrosectomy (MAP) Rhomboid” Approach for Extended Middle Cranial Fossa Lesions Extending into Posterior Cranial Fossa

Objective: Extended middle cranial fossa approach with transtentorial extension (Kawase's Triangle approach) is an established operative technique for anterior petrosectomy. We used cadaveric model and performed computerized quantitative analysis to compare 'Kawase's' and 'Modified Anteior Petrosectomy (MAP) ie Dolenc's + Kawase's' approach for lesions around petroclival region.

Extended endoscopic endonasal transclival approach to the ventrolateral brainstem and related cisternal spaces: anatomical study

Advances in endoscopic endonasal skull base surgery have led to the development of new routes to areas beyond the midline skull base. Recently, feasible surgical corridors to the lateral skull base have been described. The aim of this study was to describe the anatomical exposure of the ventrolateral brainstem and posterior fossa through an extended endoscopic endonasal transclival transpetrosal and transcondylar approach. Six human heads were used for the dissection process. The arterial and venous systems were injected with red- and blue-colored latex, respectively. A pre- and postoperative computed tomography (CT) scan was carried out on every head. The endoscopic endonasal transclival approach was extended through an anterior petrosectomy and a medial condylectomy. A three-dimensional model of the approach was reconstructed, using a dedicated software, from the overlapping of the pre- and post-dissection CT imaging of the specimen. An extended endoscopic transclival approach allows to gain access through an extradural anterior petrosectomy and medial condylectomy to the anterolateral surface of the brainstem and the posterior fossa. Two main intradural anatomical corridors can be described: first, between the V cranial nerve in the prepontine cistern and the VII-VIII cranial nerves in the cerebellopontine and cerebellomedullary cistern; second, between the VII-VIII cranial nerves and the IX cranial nerve, in the premedullary cistern. Extending the transclival endoscopic approach by performing an extradural anterior petrosectomy and a medial condylectomy provides a safe and wide exposure of the anterolateral brainstem with feasible surgical corridors around the main neurovascular structures.

Middle cranial fossa approach with and without anterior petrosectomy

The middle cranial fossa approach is a useful technique for surgical treatment of many diseases especially those involving the internal auditory canal. The technique may be extended to involve a petrosectomy making the surgery very versatile. The approach is commonly indicated for small lesions when hearing preservation is possible. Adequate exposure is obtained and common morbidities associated with more conventional approaches are often avoided.

Microsurgical Localization of the Cochlea in the Extended Middle Fossa Approach

Objective In the extended middle fossa approach, a portion of the petrous bone known as Kawase's rhomboid can be drilled to expose the posterior fossa through a middle fossa corridor. During this bony resection, the cochlea is placed at risk. The objective of this study was to objectively detail the position of the cochlea in relation to reliable surgical landmarks. Methods Eleven cadaveric specimens were dissected-including six cadaveric heads and five dry temporal bones by means of an anterior petrosectomy with skeletonization of the cochlea. Three anatomic measurements describing the location of the cochlea in relation to the extrapolated intersection of the greater superficial petrosal nerve (GSPN) and facial nerve were recorded. These measurements were then correlated with thin-cut temporal bone computed tomography scans from 25 patients with morphologically normal inner ears. Results In the cadaveric specimens, the anterior border of the membranous basal turn of the cochlea was located an average of 7.56 mm (6.4 to 8.9 mm) anterior to the extrapolated junction of the GSPN and facial nerve, as measured along the course of the GSPN. The medial border of the membranous cochlea (medial margin of basal turn) was located an average of 8.2 mm (6.9 to 8.9 mm) medial to the extrapolated junction of the GSPN and facial nerve, as measured along the course of the facial nerve. The average maximum distance from the extrapolated junction of the GSPN and facial nerve to the membranous cochlea was 9.3 mm (8.2 to 10.3 mm). These anatomic measurements correlated well with radiologic measurements of the same parameters. Conclusion When drilling Kawase's rhomboid, it is useful to locate the extrapolated junction of the GSPN and the facial nerve. Drilling of the anteromedial petrous bone outside of a radius of 12.5 mm from the extrapolated junction of GSPN and facial nerve appears to be associated with a low degree of risk to the cochlear apparatus.

Intradural anterior petrosectomy for petroclival meningiomas: a new surgical technique and results in 5 patients

Excision of petroclival meningiomas remains a surgical challenge. Extradural anterior petrosectomy is widely used as a skull base approach for these tumors; however, this approach has significant procedure-related morbidity. The authors describe an alternative technique of tailored intradural petrosectomy for removal of petroclival meningiomas. This technique was used successfully in 5 patients. Gross-total or near-total resection was possible in 2 patients, whereas a subtotal removal was achieved in 3 patients, without significant morbidity. The petrous drilling was tailored depending on the extent of tumor. Transsylvian intradural anterior petrosectomy is a safe approach for petroclival meningiomas. This approach avoids problems related to subtemporal retraction and rationalizes the degree of bone drilling.

Endoscopic approaches to the trigeminal nerve and clinical consideration for trigeminal schwannomas: a cadaveric study

The course of the trigeminal nerve straddles multiple fossae and is known to be very complex. Comprehensive anatomical knowledge and skull base techniques are required for surgical management of trigeminal schwannomas. The aims of this study were to become familiar with the endoscopic anatomy of the trigeminal nerve and to develop a minimally invasive surgical strategy for the treatment of trigeminal schwannomas. Ten fresh cadavers were studied using 5 endoscopic approaches with the aid of 4-mm 0° and 30° endoscopes to identify surgical landmarks associated with the trigeminal nerve. The endoscopic approaches included 3 transcranial keyhole approaches (the extradural supraorbital, extradural subtemporal, and retrosigmoid approaches), and 2 endonasal approaches (the transpterygoid and the transmaxillary transpterygoid approaches). The trajectories of the extradural supraorbital, transpterygoid, and extradural subtemporal approaches corresponded with the course of the first, second, and third divisions of the trigeminal nerve, respectively. The 3 approaches demonstrated each division in intra- and extracranial spaces, as well as the Meckel cave in the middle cranial fossa. The interdural space at the lateral wall of the cavernous sinus was exposed by the extradural supraorbital and subtemporal approaches. The extradural subtemporal approach with anterior petrosectomy and the retrosigmoid approach visualized the trigeminal sensory root and its neighboring neurovascular structures in the posterior cranial fossa. The transmaxillary transpterygoid approach revealed the course of the third division in the infratemporal fossa. The 5 endoscopic approaches effectively followed the course of the trigeminal nerve with minimal invasiveness. These approaches could provide alternative options for the management of trigeminal schwannoma.

The history of the combined supra- and infratentorial approach to the petroclival region

Lesions of the ventrolateral brainstem, clivus, and cerebellopontine angle pose significant challenges for surgeons, and the rate of morbidity and mortality from classic neurosurgical approaches has proven to be unacceptably high. Early attempts to expose this region consisted primarily of an extended suboccipital craniectomy, with opening of the tentorium and ligation of the sigmoid sinus for additional exposure. During the 1960s, technological innovations including the surgical microscope and the pneumatic drill allowed surgeons to gain additional exposure by removing more bone from the base of the skull. This let surgeons define combined infra- and supratentorial approaches, which rely less on brain retraction to resect these difficult tumors successfully. These approaches rely on a combined posterior mastoid approach with an anterior petrosectomy. The evolution of this approach is discussed in this paper.

Epidural anterior petrosectomy with subdural visualization of sphenobasal vein via the anterior transpetrosal approach—technical case report

The drainage of the superficial middle cerebral vein (SMCV) is classified into four subtypes. The sphenobasal vein (SBV) drains from the SMCV to the pterygoid venous plexus at the temporal skull base. Epidural procedures in the standard anterior transpetrosal approach (ATPA) may damage the route of the SBV. We report a case in which modified surgical procedures via the ATPA were used to preserve the SBV. A 45-year-old man complained of right facial pain. Magnetic resonance images revealed a right cerebellopontine tumor suggestive of an epidermoid cyst. Right carotid angiography revealed that the SMCV drained into the pterygoid venous plexus via the SBV. The convexity dura mater of the temporal lobe was cut and the anterior part of the temporal lobe was retracted subdurally. The SBV was visualized from the subdural side. The basal dura mater of the temporal lobe posterior to the SBV was cut and the posterior part of the temporal lobe was retracted epidurally. After dissecting the dura mater medial to the greater petrosal nerve and to the edge of the petrous apex, the petrous apex was exposed and drilled out without injuring the SBV. The superior petrous sinus and the tentorium were cut. The tumor compressed the root exit zone of the trigeminal nerve. The tumor was grossly totally removed. The modified ATPA (epidural anterior petrosectomy with subdural visualization of the SBV) is effective in preserving the SBV.

Case of a 4-Year-Old Boy Who Underwent Staged Resection of an Atypical Hemangiopericytoma Arising from Meckel's Cave

Intracranial hemangiopericytoma is a rare entity, accounting for less than 1% of CNS tumors; it is exceptionally infrequent among the pediatric population. We describe a case of an atypical hemangiopericytoma arising from Meckel's cave in a 4-year-old boy. The patient was in remission for acute lymphoblastic leukemia when he developed progressive gait difficulty, nausea, and vomiting. He was found to have a 6-cm dumbbell-shaped lesion extending from Meckel's cave to the root entry zone of the trigeminal nerve, which was not appreciated on a screening MRI done 12 months prior. Notably, the patient also had elevated parathyroid hormone levels. An external ventricular drain was placed to treat clinical hydrocephalus and confirm negative cytology for leukocytic disease. Initially, a retrosigmoid craniectomy was performed for resection of the tumor within the cerebellopontine angle and to obtain tissue for diagnosis. Final pathology returned as infantile hemangiopericytoma with recommendation for complete surgical resection. The patient underwent a preauricular infratemporal craniotomy with anterior petrosectomy for removal of the tumor within the middle fossa. The patient had improvement in his left-sided hemiparesis, but did sustain permanent injury to the trigeminal nerve secondary to infiltration of tumor within the trigeminal nerve. His hyperparathyroidism normalized following the procedure. Skull base tumors in the pediatric population are generally rare, and this subtype in particular is represented by a paucity of data in the neurosurgical literature. This is the first description of treatment of this type of tumor in this location in the pediatric population.

Custom-Tailored Anterior Petrosectomy within Surgical Approaches to the Petroclival Region

Custom-Tailored Anterior Petrosectomy within Surgical Approaches to the Petroclival Region