Object: Stereotactic radiosurgery has been reported to be an effective alternative to surgical removal of small to medium benign meningiomas as well as an adjuvant treatment modality to reduce the risk of tumor progression after subtotal resection. Little is known, however, regarding the growth patterns of meningiomas that fail to stabilize after radiosurgery. Methods: The authors report 13 cases of benign skull base meningiomas World Health Organization Grade I that demonstrated progression after radiosurgical treatment as a primary or an adjuvant therapy. Several tumors demonstrated rapid growth immediately after radiosurgical treatment, whereas other lesions progressed in a very delayed manner in some patients up to 14 years after treatment.
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Correspondence Address: Dr. Methods: A retrospective analysis was performed on 10 consecutive patients with clinoidal meningiomas who underwent surgical resection at the Bangabandhu Sheikh Mujib Medical University and other private clinics between May and July A standard pterional craniotomy technique consisting of extradural anterior clinoidectomy, coupled with optic canal unroofing and optic nerve sheath opening was used in all patients.
All patients had thorough preoperative and postoperative ophthalmological evaluations. The follow-up period ranged from 6 to 42 months. Results: Total resection was achieved in 5 The majority of the patients with preoperative visual impairment experienced significant visual improvement 7 of 10 patients; Conclusion: In the majority of patients with clinoidal meningiomas, total resection may be achieved with minimal complications.
Keywords Clinoidal meningiomas, pterional craniotomy, extradural anterior clinoidectomy Introduction Anterior clinoidal meningiomas arise from the meningeal covering of the anterior clinoid process. In the classical neurosurgical literature, anterior clinoidal meningiomas have not been separated from medial sphenoid wing or inner sphenoid wing meningiomas [ 1 , 2 ]. However, accumulating anatomical knowledge and clinical experience has shown that anterior clinoidal meningiomas have unique anatomical and clinical characteristics that puts them apart from meningiomas of the medial sphenoid wing [ 2 , 3 ].
Therefore anterior clinoidal meningiomas should be considered a separate clinical entity [ 2 - 4 ]. Visual loss is the very common presenting symptom in these tumors [ 5 ]. The characteristic onset usually occurs with unilateral failure of vision loss associated with primary optic atrophy [ 5 , 6 ]. In some patients, loss of vision may extend to the uninvolved eye [ 7 ]. Visual field defects in the form of concentric narrowing of the visual field, central scotoma, and temporal hemianopsia can be seen in patients; however, the extent depends on the degree of the involvement of the chiasm and the optic nerves [ 6 , 8 ].
Headache is another most common symptom in these tumors, generally over the orbital or retroorbital field [ 9 ]. Although the visual problems are the major cause of presenting symptoms in anterior clinoidal meningiomas The growth potential of the latter tumors may result in early impingement on the optic apparatus.
However, for the anterior clinoidal meningiomas, this is true only for Al-Mefty group III tumors that encroach on the optic nerve at the optic foramen [ 10 ]. Several classification schemes have been proposed as methods for predicting surgical outcome. This scheme considers the origin of the tumor and its invasion pattern in the region of the clinoid process as indicators of resectability.
It differentiates among Group I, lower clinoidal meningiomas no arachnoidal dissection plane between the internal carotid artery ICA and tumor ; Group II, distal or lateral clinoidal meningiomas which do have an arachnoidal plane between ICA and tumor and Group III, meningiomas that originate at the optic foramen.
In Group III tumors, the arachnoidal membrane is present between the ICA and the tumor but may be absent between the optic nerve and the tumor [Figure 1] [ 12 ].
Figure 1. Because anterior clinoidal meningiomas tend to grow upward, true invasion of the cavernous sinus is very rare. The current literature on anterior clinoidal meningiomas documents a very wide range of cavernous sinus invasion rates, ranging from 0 to We believe that this variability is, in part, a reflection of the lack of objective and universal nomenclature among authors. This problem has led to some medial sphenoid wing meningiomas being analyzed as part of the clinoidal group [ 13 ].
Based on the new classification, the coronal diameter of the tumor is combined with the classical Al-Mefty group designation.
Each tumor was graded typed with a numerical number denoting the Al-Mefty grouping and a capital letter representing the tumor size on coronal section [ 14 ]. A tumor was defined as type A if it was measured less than 2 cm, type B if it was 2 to 4 cm, and type C giant if it was greater than 4 cm.
These designations were applied to each group in the current Al-Mefty classification [Figure 1] [ 12 ]. Many surgeons used various skull-base approaches with or without intra- or extradural removal of anterior clinoid for resecting these challenging tumors. The recent articles by Al-Mefty [ 14 ] , Lee et al. Mathiesen et al. All patients were investigated preoperatively with coronal computed tomography CT and triplanar contrast-enhanced magnetic resonance imaging of brain.
Digital subtraction angiography and CT angiogram were done in some cases to delineate the anatomy of the cerebral circulation, encasement of major vessels, arterial displacement, and blood supply. Visual testing that included determination of visual acuity, visual field and fundal photography was performed preoperatively and postoperatively in all cases.
Al-Mefty [ 14 ] and Lee et al. The patients were positioned in supine with head turned contraleteral degree angle, fixed with three pin head fixators. Standard pterional craniotomy was done in all cases. Following pterional craniotomy extradural anterior clinoidectomy was done either by high speed drill or bone forceps [Figure 2].
Figure 2. Following craniotomy shows removal of anterior clinoid process and unroofing of optic foramen. Extradural identification of optic nerve and clinoidal carotid artery was done. Curvilinear durotomy over the tumor was done which was extended to the optic nerve or carotid artery in a T fashion to enhance close proximity of optic nerve, carotid artery and tumor.
Peripheral dissecting of tumor from the brain parenchyma was done following bipolar cautery of the feeding vessels to end from brain. Finally, delicate dissection from middle cerebral artery MCA , anterior cerebral artery ACA , posterior communicating artery PCOM , carotid bifurcation area, optic nerve and chiasm was done. Dural closure was done with or without graft, bone and wound was closed in multiple layers. We operated upon 10 cases of clinoidal meningioma.
Among them 3 were male and 7 were female [Table 1]. The ages of patients ranged from years. Gross total removal was achieved in 5 Figure 3. A Preoperative axial contrast magnetic resonance imaging of brain shows homogenously brilliant contrast enhancing benign tumor; B postoperative axial contrast computed tomography scan of brain shows complete removal of the tumor.
Figure 4. A Preoperative coronal contrast magnetic resonance imaging of brain shows homogenously brilliant contrast enhancing tumor; B postoperative computed tomography scan shows removal of anterior clinoid process with complete removal of the tumor.
In our study most of the patients had limited complications. Only one patient had complicated by hematoma and another, patient had ICA injury [Table 4]. In our series, we found visual improvement in 7 cases Figure 5. Humphrey visual field test. Figure 6. A Preoperative VF left eye with upper temporal field; B postoperative VF left eye with significant visual improvement defect. Papilledema also improved significantly after removal of tumors as shown in Figures 7 and 8.
Figure 7. A Preoperative fundal photography right eye with primary optic atrophy; B postoperative fundal photography right eye with slight improvement.
Figure 8. A Preoperative fundal photography left eye with normal findings; B postoperative fundal photography left eye with static findings. The profile of the patients with clinoidal meningioma is shown in Table 6. The traditional approach for the resection of anterior clinoidal meningiomas is the pterional intradural transsylvian approach, which begins with splitting the sylvian fissure, releasing cerebrospinal fluid, and debulking the tumor, and then proceeding with peripheral tumor dissection from neurovascular structures [ 19 - 21 ].
In this series, we present our experience using the pterional craniotomy with extradural drilling of anterior clionoid process. The surgical challenges are associated with these giant tumors from their size, difficult location, as well as the dissection, and preservation of the critical neurovascular structures like the cavernous sinus, cranial nerves, ICA, ACA, MCA and anterior choroidal artery that they inevitably involve or encase [ 22 - 24 ].
These challenges are increased by tensed brain, secondary edema, and tumor mass effect [ 18 , 25 ]. The concept of an extradural approach to skull base tumors is not new. There are 2 main challenges in the safe removal of giant tumors: 1 how to safely locate the important arteries and the optic apparatus inside these giant tumors, and 2 how to avoid damage to tensed brain during approach, dissection, and tumor removal [ 27 ].
We presumed that the best way to avoid damaging the ICA and optic nerve was to locate and dissect them in areas in which the anatomy remains relatively normal, with minimal distortion from the tumor. Extradural clinoidectomy solves this problem [ 28 , 29 ]. The extradural skull base approach that was used in our patients is similar to the technique reported by Lee et al. They reported on 15 patients with somewhat smaller anterior clinoidal meningiomas mean diameter 3.
This good result could be related to their extradural approach and early optic nerve decompression. In our series, we achieved visual improvement in 7 cases In another study, 20 patients with preoperative visual deficits due to giant medial sphenoid wing meningiomas, Behari et al.
The majority of patients in the series of Behari et al. The team of Behari et al. In a series of 35 patients with medial sphenoid wing meningiomas mean diameter 4. Pamir et al. Among 26 patients who had preoperative visual deficits, The Russell and Pamir teams used an intradural approach.
Tomasello et al. Behari et al. In our series, 3 patients In 1 patient, the hemiparesis was caused by intracranial hematoma due to intraoperative hematoma. In other 2 patients, the deficit was most likely due to manipulation of perforating vessels encased by the tumor.
Goel et al. Injury to small perforating arteries during tumor resection is a known cause of neurological deterioration, even when the large parent vessels are well preserved [ 32 , 33 ]. In conclusion, giant anterior clinoidal meningiomas are very challenging tumors. We prefer an extradural skull base approach to the tumor, including extradural unroofing of the optic canal, extradural clinoidectomy, early optic nerve decompression, and early identification and control of the clinoidal carotid artery followed by removal of the remaining tumor.
Surgical management of clinoidal meningiomas: 10 cases analysis
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Patterns of Skull Base Meningioma Progression After Failed Radiosurgery
Correspondence Address: Dr. Methods: A retrospective analysis was performed on 10 consecutive patients with clinoidal meningiomas who underwent surgical resection at the Bangabandhu Sheikh Mujib Medical University and other private clinics between May and July A standard pterional craniotomy technique consisting of extradural anterior clinoidectomy, coupled with optic canal unroofing and optic nerve sheath opening was used in all patients. All patients had thorough preoperative and postoperative ophthalmological evaluations. The follow-up period ranged from 6 to 42 months. Results: Total resection was achieved in 5 The majority of the patients with preoperative visual impairment experienced significant visual improvement 7 of 10 patients;