Minimal Anterior and Posterior Combined Transpetrosal Approach for Posterior Clinoid Process Meningiomas

Abstract

BACKGROUND AND OBJECTIVES:

Posterior clinoid process meningiomas (PCPMs) are extremely rare tumors arising from the central skull base and are surgically challenging because of their proximity to critical neurovascular structures. Although endoscopic endonasal approaches have been reported for small lesions, an optimal strategy for medium-to-large PCPMs remains controversial. To evaluate the surgical technique and clinical outcomes of the minimal anterior and posterior combined (MAPC) transpetrosal approach for medium-to-large PCPMs.

METHODS:

We retrospectively reviewed 5 consecutive patients with PCPMs who underwent microsurgical resection by the MAPC transpetrosal approach between 2018 and 2024. This approach involves limited petrous bone drilling combined with wide opening of Meckel's cave to mobilize the trigeminal nerve, providing a posterolateral corridor between the trigeminal and trochlear nerves. Surgical outcomes, extent of resection, complications, and follow-up results were analyzed.

RESULTS:

The mean patient age was 54.6 years, and the mean tumor diameter was 33.7 mm. Gross-total resection was achieved in 2 patients (40%) and subtotal resection in 3 (60%). Transient cranial nerve deficits, mainly involving oculomotor nerves, occurred postoperatively but improved within 3 months. No surgery-related mortality, cerebrospinal fluid leakage, visual deterioration, or vascular complications occurred. Adjuvant stereotactic radiosurgery or radiotherapy was performed for residual tumors in 2 patients. During a mean follow-up of 55 months, no tumor recurrence was observed.

CONCLUSION:

The MAPC transpetrosal approach provides a safe and effective surgical corridor for medium-to-large PCPMs and enables maximal safe resection with acceptable morbidity.

ABBREVIATIONS:

EEA

endoscopic endonasal approach

EOR

extent of resection

MAPC

minimal anterior and posterior combined

PCPMs

posterior clinoid process meningiomas

SPS

superior petrosal sinus

SPV

superior petrosal vein

SRS

stereotactic radiosurgery

SRT

stereotactic radiotherapy.

Posterior clinoid process meningiomas (PCPMs) are extremely rare lesions arising from the posterior clinoid process of the sphenoid bone and represent one of the most challenging tumors of the central skull base. Their surgical management is particularly demanding because these tumors develop near critical neurovascular structures, including the internal carotid artery (ICA), basilar artery, cranial nerves III-VI, and the pituitary stalk.^1-6

Historically, several transcranial approaches have been used for PCPMs, including the pterional, orbitozygomatic, subtemporal, and presigmoid transpetrosal approaches.

More recently, the endoscopic endonasal approach (EEA) has been applied to selected cases, particularly for small midline lesions.⁷

However, the optimal surgical strategy for medium-to-large PCPMs remains controversial, largely because of the complex anatomic relationships and the risk of injury to surrounding neurovascular structures.

At our institution, we have previously used the anterior and posterior combined transpetrosal approach for lesions involving the petroclival and retrochiasmatic regions. Subsequently, we developed a modified technique—the minimal anterior and posterior combined (MAPC) transpetrosal approach—designed to reduce operative invasiveness while maintaining adequate surgical exposure.^8-12

In this study, we describe the surgical technique of the MAPC transpetrosal approach and report the clinical outcomes in 5 consecutive patients with PCPMs treated using this method.

METHODS

We retrospectively reviewed 5 consecutive patients with benign (World Health Organization grade I) PCPMs who underwent microsurgical resection by the MAPC transpetrosal approach at Osaka Metropolitan University Hospital (formerly Osaka City University Hospital) between 2018 and 2024. Written informed consent was obtained from the patients for the surgical procedure and publication of this report. This study was approved by the Institutional Review Board of Osaka Metropolitan University.

All cases were included in this study and analyzed retrospectively using the electronic medical record system. In all patients, computed tomography, MRI, and digital subtraction angiography were performed preoperatively to evaluate tumor location, tumor extension, vessel encasement, calcification, and cavernous sinus invasion. The extent of resection (EOR) was calculated based on the MRI obtained within 1 week after surgery in comparison with the preoperative MRI. Cranial nerve status and Karnofsky Performance Status were retrospectively assessed by reviewing the clinical records. Recurrence or regrowth was defined as interval tumor progression on follow-up contrast-enhanced MRI.

To demonstrate the surgical technique in detail, Case 4 is presented as the illustrative case (Video).

A 60-year-old woman presented with right oculomotor nerve palsy and was found to have a 36-mm tumor arising from the right posterior clinoid process (Figure 1A-1D). Feeders from the right meningohypophyseal trunk were identified, and preoperative embolization was performed (Figure 1E). Preoperative venous-phase digital subtraction angiography demonstrated that temporal lobe venous drainage was mainly through the vein of Trolard. No dominant venous drainage route, such as the sphenobasal vein, sphenopetrosal vein, or venous plexus around the foramen ovale, crossed the planned middle fossa surgical corridor. Therefore, extradural dissection of the middle fossa floor was considered feasible without compromising major venous outflow (Figure 1F), and tumor resection was performed by the MAPC transpetrosal approach.

FIGURE 1.

Illustrative case (Case No. 4). A-D, Preoperative axial computed tomography and axial, coronal, and sagittal T1-weighted magnetic resonance images with gadolinium administration. The tumor occupies the retrosellar region on the right side and compresses the internal carotid artery anteriorly and the brainstem posteriorly. E and F, Preoperative digital subtraction angiography showed tumor staining from the meningohypophyseal trunk in the arterial phase, and the venous drainage of the temporal lobe was primarily mediated by the vein of Trolard.

Patient Positioning and Skin Incision

To prevent brain injury caused by temporal lobe retraction during surgery, a lumbar drain is inserted after induction of general anesthesia. The patient is then placed in the semi-prone park-bench position with the vertex tilted downward and the head rotated so that the temporal region becomes parallel to the floor, and fixed in a 3-point head holder. The skin incision begins anterior to the tragus at the superior margin of the zygomatic arch, curves posteriorly around the auricle, and extends downward to the posterior edge of the mastoid process (Figure 2A). After flap elevation, a pedicled temporalis fascia-periosteal flap based on the sternocleidomastoid muscle is harvested (Figure 2B). This flap is later used for dural reconstruction to prevent postoperative cerebrospinal fluid leakage.

FIGURE 2.

Intraoperative photographs demonstrating the minimal anterior and posterior combined transpetrosal transpetrosal approach (Case 4). A, Skin incision beginning anterior to the tragus along the superior border of the zygomatic arch and curving posteriorly around the auricle to the mastoid region. B, Harvesting of a pedicled temporalis fascia–periosteal flap based on the sternocleidomastoid muscle for dural reconstruction. C, Burr-hole placement at 6 anatomic landmarks: the asterion, supramastoid crest-squamosal suture junction, mastoid emissary foramen, root of the zygoma, and anterior and posterior squamosal suture points. D, Temporal craniotomy with thinning of the outer mastoid cortex in a triangular fashion to facilitate cosmetic reconstruction. E, Minimal drilling of the petrous ridge medial to the geniculate ganglion, exposing the SPS. F, Tentorial incision after division of the SPS anterior to the superior petrosal vein entry point to preserve venous drainage. G, Wide opening of Meckel's cave with mobilization of the trigeminal nerve (CN V). H, Internal tumor debulking after coagulation of the dural attachment; the inferior tumor portion is exposed between CN V and the trochlear nerve (CN IV). I, Additional tumor debulking after incision of the lateral wall of the cavernous sinus superior to the tentorial entry of CN IV. J, Exposure of the BA after removal of the posterior fossa tumor component. K, Identification of the SCA. L, Anterior dissection along the anterior petroclinoid ligament with identification of the ICA. M, Oculomotor nerve (CN III) displaced by the tumor in the deep operative field. N, Subtotal tumor removal with preservation of adjacent neurovascular structures. O, Skull base reconstruction using fibrin glue-soaked abdominal fat to obliterate mastoid air cells and coverage of the dural defect with a pedicled temporalis fascia-periosteal flap. P, A volume-rendered image reconstructed from noncontrast head computed tomography data, demonstrating the postoperative skull morphology. BA, basilar artery; CN, cranial nerve; ICA, internal carotid artery; SCA, superior cerebellar artery; SPS, superior petrosal sinus; SS, sigmoid sinus.

Craniotomy

Temporal craniotomy is performed before mastoidectomy.

To avoid injury to the sigmoid sinus, 6 burr holes are placed at anatomic landmarks. The first is at the asterion, the second at the junction of the supramastoid crest and squamosal suture, the third at the mastoid emissary foramen, the fourth at the root of the zygoma, and the fifth and sixth anterior and posterior to the squamosal suture of the temporal bone (Figure 2C). After temporal craniotomy, the outer surface of the mastoid is thinned in a triangular fashion so that the bone can be replaced at the end of surgery, thereby preventing cosmetic deformity (Figure 2D). The sigmoid sinus is carefully exposed from the transverse-sigmoid junction to its short horizontal segment.

Minimal Petrous Bone Removal

In the middle fossa, the middle meningeal artery is coagulated and divided, and the greater petrosal nerve is dissected free. By incising and reflecting the periosteal dura, the petrous ridge is exposed up to the trigeminal impression while exposing V3 and V2 of the trigeminal nerve. In the posterior fossa, the dura anterior to the sigmoid sinus is carefully elevated from the posterior surface of the petrous bone, and the endolymphatic sac is incised to expose the entrance of the internal auditory canal extradurally. The location of the geniculate ganglion is identified using electrical stimulation through the thin cortical bone and facial electromyography. After dural dissection is completed, the petrous ridge is drilled medial to the geniculate ganglion with a curved drill covered along its shaft, thereby exposing the superior petrosal sinus (SPS) (Figure 2E). During drilling, care is taken not to injure the membranous labyrinth of the semicircular canals to preserve hearing. By minimizing the extent of petrous bone removal, operative time can be shortened.

Dural Opening

The middle fossa dura is incised along the SPS on the inferior surface of the temporal lobe. The dural incision is extended as far anteriorly as possible, and medially to the lateral edge of Meckel's cave. Within the space created by petrous bone removal, the dura is incised anterior to the sigmoid sinus, and the point where the superior petrosal vein (SPV) drains into the SPS is identified. The SPS is divided anterior to the SPV entry point to preserve venous outflow. The tentorium is incised posteriorly from the SPS division site toward the tentorial edge, just posterior to the dural entry point of the trochlear nerve (Figure 2F). Meckel's cave is widely opened anteriorly to mobilize the trigeminal nerve (Figure 2G).

Tumor Removal

The temporal lobe is retracted superiorly. After the inferior surface of the tumor was exposed through the corridor between the trigeminal and trochlear nerves, the accessible dural attachment was first coagulated to reduce tumor vascularity. Stepwise internal decompression was then performed to collapse the tumor capsule, thereby expanding the surgical field and creating additional working space (Figure 2H). Next, the lateral wall of the cavernous sinus is incised superior to the tentorial entry point of the trochlear nerve, and further coagulation of the tumor attachment and internal decompression are performed (Figure 2I). After resection of the posterior fossa component, the basilar artery becomes visible (Figure 2J). More superiorly, the superior cerebellar artery is identified (Figure 2K). The tumor attachment is then dissected anteriorly along the anterior petroclinoid ligament, and the ICA is identified at the anterior margin (Figure 2L). In the deep operative field, the oculomotor nerve displaced by the tumor can be identified (Figure 2M). This sequence enables safe maximal resection of the lesion while reducing the risk of injury to the surrounding critical structures (Figure 2N).

Skull Base Reconstruction

The opened mastoid air cells are obliterated with abdominal fat soaked in fibrin glue, and the dural defect is completely covered with the pedicled temporalis fascia-periosteal flap (Figure 2O). The temporal bone and outer mastoid cortex are repositioned and fixed using titanium miniplates (Figure 2P).

In this illustrative case (Case 4), postoperative MRI demonstrated slight residual tumor along the oculomotor nerve, although most of the lesion had been removed (Figure 3A-3C). Transient right trochlear nerve palsy with diplopia developed postoperatively but resolved within 1 month. The preexisting right oculomotor nerve palsy also improved within 3 months after surgery.

FIGURE 3.

A-C, Postoperative axial, coronal and sagittal T1-weighted magnetic resonance images with gadolinium administration. The tumor was subtotally resected, with residual tumor remaining around the oculomotor nerve.

RESULTS

The cohort consisted of 1 man and 4 women, with a mean age of 54.6 years (range, 24-72 years). The mean tumor diameter was 33.7 mm (range, 18.1-57 mm), and preoperative imaging demonstrated cavernous sinus invasion in 3 of 5 patients. The tumor was located on the right side in 4 patients and on the left side in 1 patient. Table 1 summarizes the clinical outcomes of the 5 patients who underwent the MAPC transpetrosal approach. Preoperative embolization was performed in 4 of 5 patients. EOR was GTR in 40% (2/5) and STR in 60% (3/5). STR was selected in 1 patient because of firm adhesion to the ICA and in 2 patients because of tight adhesion to the oculomotor nerve.

TABLE 1.

Characteristics of 5 Patients With Posterior Clinoid Process Meningiomas Resected by a Minimal Anterior and Posterior Combined Transpetrosal Approach

Case no.	Age (y), sex	Tumor diameter (mm)	Side	Lateral extension ICA encasement	PF extension	Cavernous sinus extension	Calcification	Preoperative deficit	Preoperative embolization
1	59, male	30	Left	−	+	+	−	Tumoral bleeding (SAH)	+
2	24, female	27.6	Right	−	+	+	+	CNV	+
3	58, female	18.1	Right	−	+	−	−	CNV	−
4	60, female	36	Right	−	+	−	−	CNII	+
5	72, female	57	Right	+	+	+	−	CNIII	+

Op. time (min)	Bleeding (mL)	Extent of resection	MIB-1 (%)	Postoperative CN status	Endocrine dysfunction	Stroke	CSF leak	Postoperative RT	Pre KPS	Post KPS	PFS (mo)
504	410	STR	3.10	Transient CNIV	−	−	−	+	80	90	90
493	180	GTR	1.20	Transient CNIII	−	−	−	+	90	100	83
330	70	GTR	2	Transient CNIV	−	−	−	−	90	100	60
518	740	STR	1	Partial improvement of CNII, transient CNIII, CNIV	−	−	−	−	80	80	29
584	120	STR	5.20	Complete recovery of CNIII, transient CNVI	−	−	−	−	80	90	14

MIB-1, molecular immunology borstel-1; CN, cranial nerve; CSF, cerebrospinal fluid; GTR, gross total resection; ICA, internal carotid artery; KPS, Karnofsky Performance Status; PF, posterior fossa; PFS, progression free survival; RT, radiation therapy; SAH, subarachnoid hemorrhage; STR, subtotal resection.

There were no surgery-related deaths, and no postoperative cerebrospinal fluid leakage or infection. Postoperative MRI revealed temporal lobe edema in 1 patient, but this was asymptomatic. No complications potentially related to SPV occlusion, such as cerebellar edema, brainstem edema, cerebellar venous infarction, cerebellar hemorrhage, brainstem hemorrhage, or hydrocephalus, were observed on postoperative MRI. New postoperative neurological deficits included facial sensory disturbance in 1 patient, transient oculomotor nerve palsy in 3 patients, transient trochlear nerve palsy in 4 patients, and transient abducens nerve palsy in 1 patient. No patient developed new motor weakness.

By contrast, preoperative facial sensory disturbance improved in 2 patients, and preoperative visual dysfunction improved in 1 patient. Improvement was also obtained in the 1 patient with preoperative oculomotor nerve palsy. Postoperative Karnofsky Performance Status improved in 4 patients (80%) and remained unchanged in 1 (20%). Stereotactic radiosurgery was performed in 1 patient with a residual tumor around the ICA. In another patient with residual tumor extending from the clival region to the contralateral petrous apex, additional tumor resection by an EEA was performed, followed by stereotactic radiotherapy (SRT) (Case 2). Preoperative and postoperative gadolinium-enhanced T1-weighted images of Cases 1, 2, 3, and 5 are shown in Figure 4, excluding the illustrative case. During a mean follow-up of 55 months (range, 14-90 months), no tumor recurrence was observed, and good local tumor control was achieved in all patients.

FIGURE 4.

Preoperative and postoperative gadolinium-enhanced T1-weighted axial magnetic resonance images of Cases 1, 2, 3, and 5. A-D, Preoperative gadolinium-enhanced T1-weighted axial images. E-H, Postoperative gadolinium-enhanced T1-weighted axial images. A and E, Case 1. B and F, Case 2. C and G, Case 3. D and H, Case 5. Preoperative images demonstrate enhancing posterior clinoid process meningiomas. Postoperative images confirm substantial tumor removal with preservation of adjacent neurovascular structures.

DISCUSSION

Surgical Challenges of PCPMs

PCPMs represent a rare subset of skull base meningiomas, accounting for only a small fraction of central skull base tumors. Surgical management is complicated by their deep anatomic location and the intimate relationship with critical neurovascular structures. The posterior clinoid process is situated posterolateral to the pituitary stalk, medial to the cavernous sinus, and posterior to the paraclinoid segment of the ICA. Because these tumors enlarge, they typically displace surrounding structures in characteristic directions: the pituitary stalk anteriorly, the oculomotor nerve laterally or inferiorly, and the ICA and its branches anteriorly or superiorly. These anatomic relationships often lead to early clinical manifestations such as diplopia or visual disturbance.

Radiologically, PCPMs may be difficult to diagnose preoperatively because the dural attachment is often small and the classic dural tail sign is frequently absent. Furthermore, these lesions may mimic other parasellar tumors, including anterior clinoid meningiomas or pituitary region tumors.¹³

One useful radiological feature for differentiating PCPMs from anterior clinoid meningiomas is the direction of ICA displacement: posterior displacement is more typical of anterior clinoid meningiomas, whereas anterior displacement is more characteristic of PCPMs.¹

Surgical Approaches for PCPMs and Review of Literature

To date, 11 publications have reported the surgical treatment of PCPMs. An overview is provided in Table 2.^1-7,14-17 Except for 1 report describing endoscopic endonasal resection, all tumors were removed by transcranial approaches. The transcranial approaches used for PCPM resection included the transcavernous-transsellar approach, presigmoid-transpetrosal approach, transzygomatic subtemporal approach, basal frontotemporal orbitozygomatic transsylvian approach, frontotemporal transsylvian approach, retrosigmoid approach, combined transpetrosal approach, and endoscope-assisted far-lateral supracerebellar infratentorial approach.

TABLE 2.

Review of Literature

Source	Patients	Age	Sex	Max diameter (mm)	Approach	EOR	Complication
Nakamura and Samii14	1	41	M	ND	Front lateral and retrosigmoid approach	GTR	None
Goto and Ohata1	5	45-58 mean of age 51.6	M3, F2	ND	Combined transpetrosal approach	GTR n = 3, NTR n = 1, PTR n = 1	None
Ohba et al15	1	60	M	45	Transzygomatic approach	STR	Hemiparesis (brainstem infarction)
Shukla et al2	2	50	F	40	Transzygomatic subtemporal approach	GTR	None
		41	F	45	Transzygomatic subtemporal approach	PTR	Hemiparesis, hemianopsia, oculomotor palsy
Sodhi et al3	1	48	F	30	Frontotemporal orbitozygomatic approach	NTR	Transient ptosis
Takase et al4	2	54	F	20	Frontotemporal approach	NTR	None
		62	F	65	Frontotemporal orbitozygomatic approach	STR	Transient hemiparesis
Nanda et al5	1	66	F	45	Retrosigmoid approach	STR
Young et al16	1	53	F	ND	Orbitozygomatic transpetrosal approach	STR	Mild oculomotor and trigeminal nerve palsy
Wu et al6	1	68	F	50	Combined transpetrosal approach	STR	Transient abducens nerve palsy
Bai et al17	1	67	F	25	Endoscope assisted far-lateral supracerebellar infratentorial approach	GTR	None
Awyono et al7	1	54	F	40	Endoscopic endonasal transposterior clinoid approach	GTR	None
Present report	5	24-72 mean of age 54.6	M1, F4	18.1-57 (mean 33.7)	Minimal anterior and posterior combined transpetrosal approach	GTR n = 2, STR n = 3	Transient diplopia

EOR, extent of resection; F, female; GTR, gross total resection; M, male; ND, not described; NTR, near total resection; PTR, partial resection; STR, subtotal resection.

The EOR in the literature was: gross-total removal in 7 of 17 cases, near-total removal in 4 of 17 cases, and subtotal removal in 6 of 17 cases.

Nakamura and Samii¹⁴ reported a case of a large meningioma attached to the dorsum sellae and posterior clinoid process that was successfully resected by a 2-stage operation combining the lateral suboccipital and frontolateral approaches. Nanda et al⁵ also reported the retrosigmoid approach. However, these approaches may be limited by the depth of the operative field, difficulty in optic nerve decompression, and restricted access to anterior tumor extension.⁶

Bai et al reported the endoscopic far-lateral supracerebellar infratentorial approach. This approach allows early identification of the oculomotor and trochlear nerves and enables direct visualization of the lesion. In addition, the ICA and its branches can be identified under direct vision. On the other hand, the superior extent of the tumor may only become exposed after sufficient removal of the inferior tumor portion.¹⁷

Dolenc emphasized the rarity of PCPMs. Among all central skull base meningiomas treated over a 20-year period, only 6 cases were PCPMs, accounting for merely 0.7% of all central skull base meningiomas.¹⁸ He stated that the transcavernous-transsellar approach enables early decompression of the optic canal and allows gross-total resection without additional neurological deficits except for transient oculomotor nerve palsy. However, this approach has several limitations specific to posterior clinoid meningiomas. When the ICA and its branches are displaced anteriorly by the tumor, they obstruct the anterolateral surgical corridor. As a result, the tumor must be removed through the narrow interval between the ICA and its perforators, thereby increasing surgical risk. In addition, early identification of the oculomotor nerve is difficult with this approach.

If the anterolateral corridor is obstructed by the ICA and the long working distance to the posterior clinoid process becomes problematic, a theoretical solution is to shift to a more lateral approach. The transzygomatic subtemporal approach and anterior transpetrosal approach can provide a shorter and more direct route to the central portion of the tumor. However, with these approaches, the line of sight is directed downward toward the posterior fossa. By contrast, the main tumor bulk of posterior clinoid meningiomas lies superior and slightly anterior relative to the floor of the middle cranial fossa. Therefore, an approach providing an inferior-to-superior and posterior-to-anterior trajectory is considered more rational for resection of this tumor. The MAPC transpetrosal approach uses a posterolateral corridor and provides an upward and forward working trajectory ideally suited for PCPMs (Figure 5). Moreover, the oculomotor nerve can be identified early at its proximal segment, which may reduce the risk of injury.

FIGURE 5.

Illustrative schematic of the minimal anterior and posterior transpetrosal approach for posterior clinoid process meningioma. Illustration demonstrating the operative corridor of the minimal anterior and posterior transpetrosal approach to a posterior clinoid process meningioma. The tumor arises from the posterior clinoid process and displaces adjacent neurovascular structures, including the internal carotid artery, oculomotor nerve (cranial nerve III), basilar artery, and superior cerebellar artery. The posterolateral trajectory provides an inferior-to-superior and posterior-to-anterior line of sight toward the tumor origin, allowing direct access to the posterior clinoid region while avoiding the narrow interval between the internal carotid artery and its perforating branches.

Although minimal extradural petrous bone drilling is a key feature of the MAPC transpetrosal approach, the extent of petrous bone removal should be tailored to each case. In large PCPMs with significant inferior extension toward the petroclival region or prepontine cistern, the working corridor obtained by minimal petrosectomy may be insufficient for safe tumor debulking and dissection. In such cases, after intradural assessment of the operative field and tumor extension, additional petrous bone removal can be performed intradurally as needed to expand the surgical corridor, improve visualization, and facilitate safe dissection of the inferior tumor margin. Thus, the MAPC transpetrosal approach should be regarded as a flexible, tailored approach rather than a fixed extent of bone removal.

In addition, an important caveat is that in cases where venous drainage depends mainly on the sphenobasal vein or the venous plexus around the foramen ovale, dural elevation from the middle fossa floor should be minimized to preserve venous outflow.¹⁹

EEA for PCPMs

In recent years, the EEA has advanced markedly as an approach to the midline skull base. EEA provides the most direct route to midline skull base lesions without brain retraction. In addition, advances in endoscopes and rigid instruments now permit meticulous bone removal and tumor dissection even in deep operative fields under excellent visualization. A particularly distinctive advantage of this approach is that posterior clinoidectomy and treatment of the tumor attachment can be performed in the earliest phase of surgery. Reports of EEA for PCPMs have also begun to appear.⁷

At our institution, we have also achieved favorable outcomes without complications using EEA for small PCPMs measuring <2 cm (Figure 6).

FIGURE 6.

Endoscopic endonasal approach for a small posterior clinoid process meningioma. A, Preoperative gadolinium-enhanced T1-weighted axial magnetic resonance image demonstrating a small right posterior clinoid process meningioma. B, Endoscopic endonasal view after exposure of the right posterior clinoid process. C, Removal of the posterior clinoid process to access the tumor attachment. D, Coagulation and resection of the dural attachment at the posterior clinoid region. E, Tumor removal under endoscopic visualization. F, Final operative view demonstrating preservation of adjacent neurovascular structures, including the oculomotor nerve (cranial nerve III), BA, SCA, and posterior cerebral artery. G, Postoperative gadolinium-enhanced T1-weighted axial magnetic resonance image confirming gross-total resection without residual enhancement. The patient experienced an uneventful postoperative course without new neurological deficits. BA, basilar artery; CS, cavernous sinus; ICA, internal carotid artery; PCP, posterior clinoid process; PG, pituitary gland; SCA, superior cerebellar artery; SF, sellar floor.

On the other hand, EEA still has several limitations. When the tumor is large and extends laterally, sufficient tumor mobility cannot be obtained through the endonasal route alone, and safe dissection from critical neurovascular structures becomes extremely difficult. Even if paraclival ICA transposition or a translacerum approach is performed, resection may still remain insufficient.

In addition, venous bleeding from the cavernous sinus or paraclival venous plexus is often difficult to control, and hemostasis within the limited operative corridor requires considerable technical expertise. Furthermore, the risk of cerebrospinal fluid leakage remains substantial in extended EEA, and multilayer reconstruction is often necessary after resection of PCPMs associated with large bony and dural defects.

Taken together, EEA may be a useful option for small PCPMs confined to the midline, but it also has limitations in medium-to-large PCPMs. Therefore, the optimal surgical approach should be selected individually after comprehensive evaluation of tumor extension, calcification, venous anatomy, and the pattern of displacement of the surrounding neurovascular structures.

Limitations

This study has several limitations. First, it represents a retrospective analysis from a single institution. Second, the number of patients was small because PCPMs are extremely rare tumors. Larger multicenter studies are required to further validate the safety and efficacy of this approach.

CONCLUSION

The MAPC transpetrosal approach provides a safe and effective surgical corridor for the management of medium-to-large PCPMs. This technique enables maximal safe resection while minimizing surgical morbidity and may represent a valuable surgical option for these challenging skull base tumors.

Funding

This study did not receive any funding or financial support.

Disclosures

The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article.

VIDEO. This video demonstrates the minimal anterior and posterior combined transpetrosal approach for resection of a posterior clinoid process meningioma. A 60-year-old woman presented with right oculomotor nerve palsy caused by a 36-mm tumor arising from the posterior clinoid process and extending into both the middle and posterior fossa. Preoperative embolization was performed. After semi-prone park-bench positioning, a temporal craniotomy and cosmetic mastoidectomy were performed. Minimal petrosectomy was performed to adequately expose the superior petrosal sinus (SPS). The SPS and tentorium were then divided while preserving venous outflow through the superior petrosal vein (SPV). Meckel's cave was widely opened to mobilize the trigeminal nerve, providing access to the tumor through the corridor between the trigeminal and trochlear nerves. Internal tumor debulking and coagulation of the dural attachment were performed, followed by meticulous dissection from surrounding neurovascular structures to achieve safe maximal resection. Near-total resection was achieved. Postoperative deficits were transient, with favorable neurological recovery. This approach provides a wide surgical corridor with multidirectional access for complex posterior clinoid lesions.