- Department of Neurosurgery, Santa Maria Hospital, Lisboa, Portugal
Correspondence Address:
Nuno M. Simas
Department of Neurosurgery, Santa Maria Hospital, Lisboa, Portugal
DOI:10.4103/2152-7806.114796
Copyright: © 2013 Simas NM This 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: Simas NM, João Paulo Farias. Sphenoid Wing en plaque meningiomas: Surgical results and recurrence rates. Surg Neurol Int 09-Jul-2013;4:86
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Abstract
Background:Sphenoid wing en plaque meningiomas are a subgroup of meningiomas defined by its particular sheet-like dural involvement and its disproportionately large bone hyperostosis. En plaque meningiomas represent 2-9% of all meningiomas and they are mainly located in the sphenoid wing. Total surgical resection is difficult and therefore these tumors have high recurrence rates.
Methods:Eighteen patients with sphenoid wing en plaque meningiomas surgically treated between January 1998 and December 2008 were included. Clinical, surgical, and follow-up data were retrospectively analyzed.
Results:Mean age was 52.2 years and 83% were female. Five patients presented extension of dural component into the orbit and six patients presented cavernous sinus infiltration. Adjuvant radiation therapy was performed in three patients. After a mean follow-up of 4.6 years, five patients developed tumor recurrence - two patients were submitted to surgical treatment and the other three were submitted to radiation therapy. No patient presented recurrence after radiation therapy, whether performed immediately in the postoperative period or performed after recurrence. Patients without tumor extension to cavernous sinus or orbital cavity have the best prognosis treated with surgery alone. When tumor extension involves these locations the recurrence rate is high, especially in cases not submitted to adjuvant radiation therapy.
Conclusion:Cavernous sinus and superior orbital fissure involvement are frequent and should be considered surgical limits. Postoperative radiation therapy is indicated in cases with residual tumor in these locations.
Keywords: Cavernous sinus, meningioma, orbital tumor, proptosis, sphenoid wing
INTRODUCTION
En plaque meningiomas constitute a particular type of meningiomas that infiltrate the dura mater in a diffuse, sheet-like appearance, forming a thin layer that closely follows the contours of the inner table of the skull. The term “en plaque” was first used by Cushing and Eisenhardt [
En plaque meningiomas represent 2-9% of all meningiomas. [
Total removal of sphenoid wing en plaque meningiomas is difficult due to its extensive bone and dural involvement. As a result, these tumors have high recurrence rates. Cavernous sinus extension is responsible for recurrence in many circumstances.
In this study, the authors analyze the surgical results, follow-up, and recurrence patterns in a series of 18 patients.
MATERIALS AND METHODS
All patients presenting sphenoid wing en plaque meningiomas surgically treated in our hospital from January 1998 to December 2008 were included. To be classified as en plaque meningiomas the tumors had to meet the following criteria: Sheet-like dural involvement; extensive bone hyperostosis - bone invasion disproportionately large in relation to dural or intradural involvement. Nonhyperostotic sphenoid wing meningiomas, cavernous sinus meningiomas with secondary orbital involvement, primary optic nerve sheath meningiomas, and clinoidal meningiomas do not met these criteria and were excluded.
The clinical records were retrospectively reviewed and analyzed for presenting symptoms, surgical results, radiation therapy, follow-up, and recurrence rates. Computed tomography (CT) and magnetic resonance imaging (MRI) scans were also reviewed to confirm that all tumors met the criteria.
RESULTS
Clinical data
Eighteen patients presenting en plaque sphenoid wing meningiomas were surgically treated. Fifteen patients were females, representing 83% of all patients (female: male ratio 5:1). The mean age at the time of surgery was 52.2 years, ranging from 27 to 75 years. The most common presenting complaint was proptosis, referred by 16 patients. Five patients referred also visual impairment, two patients noted temporal region swelling, and two patients complained of pain in the orbital region. All signs and symptoms are listed in
Imaging findings
When planning the surgical treatment of an en plaque meningioma of the sphenoid wing, the extension of both tumor components - dural/intradural and bone involvement - have to be taken in consideration [
The dural component was located in the anterior region of the temporal fossa in 10 patients. This was the most common location of dural infiltration. Five patients presented extension of dural component into the orbit, six patients presented cavernous sinus infiltration [
Surgical treatment
The 18 patients were submitted to pterional craniotomy followed by extradural removal of the invaded bone using high speed drills, bone rongeurs and kerrison bone punches. Superolateral orbitotomy was also performed in all cases, allowing orbital decompression and removal of tumor in cases with intraorbital involvement. By removing the invaded bone we were able to decompress the superior orbital fissure as well as the orbital cavity itself, a procedure especially important in cases with proptosis. After bone removal, when needed, the dura was open and the dural/intradural component was removed. In the five cases with intraorbital extension, we also opened the periorbita and removed this tumor component. The decompression of optic canal was performed in two patients presenting visual acuity impairment preoperatively and imaging evidence of optic nerve compression due to bone invasion of the optic canal walls. Cavernous sinus tumor extension was not removed in any of the six patients who presented it, considering the high risk of postoperative neuropathy. In seven patients, the dural component was confined to the temporal fossa, presenting no extension into the orbital cavity or cavernous sinus. In these seven cases it was possible to achieve a Simpson grade II resection [
Histological analysis revealed that all tumors were World Health Organization (WHO) grade I meningiomas.
Follow-up
Proptosis improved after surgery in all 16 patients who presented it: 12 patients obtained a complete resolution while the other 4 improved significantly. In the postoperative period three patients presented a transient oculomotor deficit, one patient developed a transient cerebrospinal fluid (CSF) leak that was managed conservatively, and one patient complained of transient hyposthesia in V1 territory. The two patients submitted to optic canal decompression presented postoperative ipsilateral amaurosis. These two patients presented preoperative severe visual deficit (worse than 2/10). One of these patients became permanently amaurotic while the other patient presented a slight recovery of visual function in the upper visual field, resulting in a permanent unilateral inferior hemianopsia. In our series there was no mortality.
Adjuvant radiation therapy was performed in three patients presenting significant residual tumors: two patients with residual tumor in the cavernous sinus and one patient with residual tumor involving the cavernous sinus, sellar region and orbital apex. Regarding therapeutic modality, one patient was submitted to radiosurgery (RS) and two patients to fractionated stereotactic radiotherapy (FSRT). The radiation therapy modality was decided according to the following features: Size and configuration of the residual/recurrent tumor; distance to the optic nerve and quiasma.
No patient was lost to follow-up. After a mean follow-up of 4.6 years (range: 4 months to 11 years), five patients developed tumor recurrence (28%). The location of the recurrence, time to recurrence, and therapeutic decisions are listed in
None of the three patients submitted to immediate adjuvant radiation therapy recurred; with a mean follow-up of 3.5 years, these three patients present stable lesions, without any evidence of progression. Regarding the location of the recurrence, two patients presented cavernous sinus recurrence, two patients presented intraorbital recurrence [ The intraorbital tumor recurrence occurred earlier than the cavernous sinus recurrence. Intraorbital recurrence occurred after 2 and 3 years of follow-up while the cavernous sinus recurrence occurred after 4 and 5 years from initial surgery. The patient with a 3-year follow-up intraorbital recurrence, treated with surgery and tamoxifen, presented another recurrence again only 3 years after the second surgery. Regarding therapeutic decision after diagnosis of tumor recurrence, two patients were considered surgical candidates and submitted to a surgical treatment due to tumor volume. In one of these patients, presenting a large recurrent tumor involving the sphenoid wing, pterygoid process and extending into pterygomaxillary fossa, preoperative embolization was performed. The other three patients who presented tumor recurrence were submitted to radiation therapy: RS in two cases and FSRT in one case. After a mean follow-up of 4.6 years there was no recurrence observed after radiation therapy, whether performed immediately in the postoperative period as adjuvant therapy or performed after a recurrence.
If we analyze separately the follow-up data from three different groups: (1) patients without any tumor extension to the cavernous sinus or orbital cavity; (2) patients with cavernous sinus involvement; and (3) patients with intraorbital tumor, we can conclude that:
Group 1) - Seven patients were surgically treated for sphenoid wing en plaque meningiomas without extension to cavernous sinus or orbital cavity. None of these patients were submitted to adjuvant radiation therapy. After a mean follow-up of 3.2 years none of these patients presented a tumor recurrence. Group 2) - Six patients presented tumor extension to the cavernous sinus [ Group 3) - Five patients had intraorbital tumor extension [
DISCUSSION
Sphenoid wing en plaque meningiomas are a clinical and pathological subgroup of meningiomas defined by its particular sheet-like dural involvement and its disproportionately large bone hyperostosis. Therefore, the diagnosis is determined by this particular growing pattern rather than histological appearance. [
The first step in tumor resection is the extradural removal of all the infiltrated bone. The bone removal should be as extensive as necessary and guided by preoperative CT scan, allowing an adequate decompression of fissures and foramina of the basal cranium as well as the orbital cavity itself. This removal is performed extradurally, allowing a better protection of the underlying neural structures while the invaded bone is being drilled away. As bone infiltration is responsible for most symptoms this extensive bone removal will allow the resolution of preoperative symptoms and also prevent an early recurrence. Although bone infiltration is responsible for most symptoms, the extension of surgical resection and therefore recurrence rates are influenced mostly by the dural infiltration. Total removal of en plaque meningiomas of the sphenoid wing is very difficult to achieve. These tumors are located in a complex anatomic area and they tend to spread into foramina and fissure of the basal cranium involving the temporal fossa, the orbit, the cavernous sinus, and, more rarely, the pterygomaxillary fossa. [
Postoperative radiation therapy is still a matter of debate. Some authors recommend postoperative radiation treatment after subtotal resection if there is dural or cavernous sinus invasion and also as soon as follow-up neuroimaging demonstrates recurrent tumor, [
CONCLUSION
En plaque meningiomas of the sphenoid wing are challenging tumors that pose some particular issues in dealing with. Total removal is very difficult and carries high risk of postoperative morbidity. Cavernous sinus and superior orbital fissure involvement are considered surgical limits. Radiation therapy is effective in controlling tumor growth and should be considered for cases with residual tumor in cavernous sinus and orbital cavity.
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