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Multiple skull base meningioma: case report
Multiple Skull Base Meningioma: Case Report Aldo Spallone, M.D., Massimiliano Neroni, M.D., and Renato Giuffre`, M.D. Division of Neurosurgery, University of Rome “Tor Vergata,”, Rome, Italy
Spallone A, Neroni M, Giuffre` R. Multiple skull base meningioma: case report. Surg Neurol 1999;51:274 – 80. BACKGROUND
The incidence of multiple skull base meningiomas varies from 1 to 3% in different series. Skull base meningiomas are rare. The pathogenetic role of low-dose radiation seems to be fairly well established in the oncogenesis of meningiomas. Calvarial location and multiplicity seem to be among the distinctive features of radiation-induced meningiomas. Skull base location is a very rare occurrence, mainly because the path of irradiation does not significantly involve this region. CASE REPORT
We describe a rare case of simultaneous occurrence of two skull base meningiomas in a 66-year-old female. This patient underwent low-dose irradiation for tinea capitis when she was 8 years old. The patient complained of nuchal pain, paresthesias in both hands, and progressive weakness on her right side. She was admitted to the hospital in September 1994. An MRI showed two masses, one located at the level of the tuberculum sellae and the other at the foramen magnum. These seemed very likely to be multiple meningiomas. The latter lesion, which was more symptomatic and dangerous, was operated on first. Six months later, elective treatment of the suprasellar meningioma was performed with success. CONCLUSION
The actual role of previous head irradiation in the oncogenesis of the present meningiomas remains somewhat unclear. Proper management and judicious use of skull base surgery techniques were key factors in the successful treatment of the patient. © 1999 by Elsevier Science Inc. KEY WORDS
Multiple meningioma, skull base, low-dose head irradiation, surgical treatment.
he multiplicity of meningioma has attracted the interest of the neurosurgical community because of its relative rarity, unclear etiology and the problems related to proper management strategy. The incidence of multiple skull base meningio-
T
Address reprint requests to: Dr. Aldo Spallone, M.D., Division of Neurosurgery, University “Tor Vergata,” Via Orazio Raimondo, 00173 Rome, Italy. Received March 12, 1996; accepted September 2, 1997. 0090-3019/99/$–see front matter PII S0090-3019(98)00087-1
mas varies from 1 to 3% in different series [1,15,19, 28,43,50]. As for the location of these meningiomas, the base of the skull is uncommon. Basal meningiomas were in fact observed in only 2 of the 14 patients harboring multiple meningiomas reported in a recent paper [13], a proportion that matches that of other published studies on multiple meningiomas [4,7,19,28,50]. We are reporting here a case of simultaneous occurrence of two meningiomas at the skull base, in the foramen magnum and in the diaphragma sellae respectively, in a woman who had received lowdose irradiation to her head many years ago. Lowdose irradiation is a recognized pathogenic factor for meningiomas in general and in particular for multiple meningiomas [36,45].
Case Report A 66-year-old woman was admitted to the hospital in September 1994. Her main complaints were nuchal pain, paresthesias in both hands, mainly on the right, and progressive weakness of her right side. The patient had had significant visual problems in the past, which had been related to hypertensive retinopathy. Her visual acuity had shown a steady decrease, mainly in her left eye, until being admitted to hospital. On examination she showed a moderate right side pyramidal weakness, with no obvious sensory or cranial nerve deficit. She had mild “piano playing finger” phenomenon in her right hand. Visual acuity was diminished to 4/50 in her left eye, and 4/10 in her right eye. A bitemporal hemianopsia was evident and a superior visual field cut was additionally present in the left eye. Computed tomography (CT) scanning showed a suprasellar mass that enhanced with contrast, as well as a lesion with similar characteristics located at the level of the foramen magnum. Selective cerebral angiography was limited to the study of the carotid system. This was attributable to the occur© 1999 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
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We decided to approach the foramen magnum lesion first as it appeared to exert significant pressure on the vital areas of the craniocervical junction and also seemed to show a definite tendency to worsen in the last months.
First Operation
MRI, sagittal (a) and axial (b) view after Gd-DTPAenhancement. An anterior foramen magnum meningioma (2.4 3 2 cm) is shown. The sagittal image (a) gives clear evidence of a 2.3 3 2.1 cm suprasellar mass with similar characteristics.
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rence of symptoms of cerebrovascular insufficiency that occurred immediately after an attempt to catheterize the right vertebral artery. This subsided as soon as the catheter was removed. The examination showed a picture compatible with the presence of a suprasellar mass. Magnetic resonance imaging (MRI) (Figure 1, a– b), before and after gadolinium enhancement, showed two masses located at the level of the tuberculum sellae and the foramen magnum respectively, which seemed very likely to be multiple meningiomas. Just by chance we discovered that this patient had had irradiation for the treatment of tinea capitis when she was 8 years old. No other information regarding the treatment could be obtained.
Surgery was performed on September 16th, 1994. After a “horse shoe” incision that went from the midline to inferior to the left mastoid process, the extradural vertebral artery was identified at the transverse process of C2; then the greater occipital nerve was identified. The artery was carefully dissected from its groove and moved inferomedially, to expose the occipital condyle and the lateral mass of C1, which were partially drilled away. This exposed 1 cm of dura lateral to the point of entry of the vertebral artery. Dural opening was complicated by significant bleeding from a hypertrophic circular sinus, which was eventually controlled with extensive use of bipolar coagulation. Also for this reason the dural cut was limited laterally to the point of entry of the vertebral artery. As soon as the extradural bleeding was under control, tumor debulking was initiated. After reducing the tumor mass, which seemed to be rather poorly vascularized, it was dissected from the surrounding left C1 and C2 roots, the spinal accessory nerve, and the vertebral artery, with relative ease. The tumor matrix anterior and superior to the point of exit of the C1 root was adequately visualized without need for extending the dural cut laterally, and was extensively coagulated. Watertight dural closure could not be achieved. Postoperatively, lumbar drainage was maintained for 10 days, after which the patient was ambulant. Continuous lumbar CSF drainage was reapplied 3 days later, as the wound showed significant bulge. It disappeared a week later, with no further problems. Histology showed a meningothelial meningioma of fibroblastic variant (Figure 2).
Second Operation The same patient was readmitted for elective treatment of her suprasellar meningioma in March 1995. Postoperative MRI (Figure 3, a– b) had shown total removal of the craniospinal mass. The patient had demonstrated a definite improvement of her hemiparesis, but visual acuity appeared to be further diminished in the left eye (2/50). Visual evoked potentials were performed on admission to the hospital and showed a reduction of amplitude of the N75-P100 complex, as well as a marked increased
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atrophic. Removal of the tumor was continued with great care until the right posterior cerebral and basilar arteries came into view deep in the surgical field, after which the hypophyseal stalk was identified and spared, and the remaining tumor removed using curved instruments and bipolar coagulation. Some fragments had to be removed blindly from behind the hypertrophic tuberculum sellae.
MRI, sagittal (a) and coronal (b) view after enhancement obtained after the first operation. These images give evidence of the suprasellar meningioma, displacing the pituitary gland and its stalk downward. The foramen magnum meningioma is no longer present.
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latency of the P100 potential. These data were compatible with a significant central visual pathway compression caused by the suprasellar mass. Surgery was performed in March 1995, using a bilateral frontobasal approach. A pericranial graft was fashioned to be used for reconstruction, and the sagittal sinus ligated proximally to allow division of the falx from the crista galli. The suprasellar mass was exposed after careful retraction of the frontal lobes and a full view of both carotid and anterior cerebral arteries, as well as of the compressed anterior optic pathways, was obtained. The mass was carefully debulked and devascularized at its bed, until the hypertrophic tuberculum sellae was reached. At this stage the reduced tumor mass could be safely dissected away from the surrounding vessels as well as from both optic nerves and the chiasm. The left optic nerve appeared to be flattened and
3
Control MRI. Sagittal (a) and axial (b– c) views show total removal of both masses.
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Photomicrogram (H-E 3 100) shows hypocellular meningothelial meningioma constituted of wide collagen bands interspersed with neoplastic cells of elongated shape.
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Hemostasis was checked, and the wound closed using the pericranial graft fashioned at the beginning of the operation. Postoperatively, visual acuity in the right eye improved significantly (from 4/10 to 7/10), as also did the hemianopsia. No significant improvement was noticed in the left eye. Postoperative MRI (Figure 4, a– b) demonstrated total removal of both masses. Histological examination showed a meningothelial meningioma with scattered psammomatous bodies (Figure 5).
Discussion MULTIPLE MENINGIOMAS Multiple meningiomas rarely occur at the base of the skull. The incidence of basal meningiomas out
Photomicrogram (H-E 3 50) of the second meningioma shows high cellularity with polymorphic lobules and syncytial features. Some lobules show cells of elongated shape immersed in wide collagen bands. Scattered psammomatous bodies were present.
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of the whole group of multiple meningiomas averaged 5% in a detailed recently published study [13]. It appeared to be slightly higher in another recent study [9]; however, it reported a smaller number of cases. A similarly low percentage of basal locations was generally observed in the relatively scanty literature on multiple meningiomas [1,4,7,10,14,19,26, 43,50], and did not seem to change in the more recently published reports in which CT scanning represented the chief diagnostic test, leading to higher diagnostic accuracy [15,27,28,31,35]. In these patients harboring multiple meningiomas, skull base tumors were, as a rule, observed in conjunction with the more frequently observed convexity or parasagittal-falx meningiomas. Simultaneous occurences of two intracranial meningiomas in two separate locations at the skull base is certainly a rare event, which to our knowledge has been mentioned in the literature only once before [40]. That patient was a 1-year-old child harboring a spinal meningioma in addition to a parasellar and a foramen magnum meningioma. HISTOLOGY OF MULTIPLE MENINGIOMAS Cushing and Eisenhardt [10] defined the condition of multiple meningiomas as one in which a patient has more that one meningioma but somewhat less than a dissemination of them. Multiple intracranial meningiomas were eventually separated into two groups [7,16]: 1. Distant multiple meningiomas (DMM), in which the lesions are located far from each other. 2. Regional multiple meningiomas (RMM), in which the lesions lie in close proximity. It has been speculated that multiple meningiomas may be actually multiple only when the lesions have a different morphology; they should be considered multicentric when the histologic pattern of the different lesions seems to be the same [8]. We found, surprisingly, that in the literature concerning multiple meningiomas, only a few papers report the histology of each surgically excised lesion [8,11,21, 22,32,40,49]. It seems from these papers that DMM show, as a rule, a different morphological pattern. This seems to be the case in our patient too; her tumors were located in separate regions, and exhibited different histological patterns. In fact, although both meningiomas could be classified as meningothelial, the presence of psammomatous bodies was a definite pattern in the lesion located in the suprasellar area, and clearly distinguished it from the meningioma operated on first.
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SKULL BASE MENINGIOMAS Craniobasal meningiomas have traditionally been considered very difficult to eradicate. The recent introduction of modern techniques of skull base surgery has definitely facilitated the removal of these lesions, by shortening the working distance, widening the surgical field, and minimizing the need for prolonged brain retraction [3,41]. This has changed the previous conservative attitude, and has resulted in widening the indications for curative surgery as well as in better results of operative management of these difficult lesions [3,17,33,38,41,47]. SURGICAL MANAGEMENT OF CRANIOSPINAL MENINGIOMAS Anteriorly located meningiomas at the craniocervical junction have represented a real surgical challenge when operated on using traditional approaches [20]. The recent introduction of the socalled extreme [5,18] or far [42] lateral approach to the craniovertebral junction has offered a definite contribution to facilitating the removal of these dangerous lesions. Mobilization of the vertebral artery (VA) and drilling of the occipital condyle has been advocated by some authors [42] to give an unobstructed view to the anterior dura, where these meningiomas may be attached. Others [18,25, 48] have argued that meningiomas in this location, although attached anteriorly, usually displace the spinal cord to one side, particularly if they have already attained a significant size. As a consequence of this, opening the dura laterally up to the point of entry of the VA, without going further laterally, should give enough space to expose the tumor matrix without the need for the brain substance to be retracted. In the present case, we operated on the more progressively symptomatic, thus, the more dangerous lesion, first. The extradural VA was carefully dissected and moved inferomedially, to drill off the lateral part of C1 and a portion of the medial occipital condyle. This exposed approximately 1 cm of the dura lateral to the point of entry of the VA. However, the dural opening, which was not extended so far laterally, was enough to obtain a wide surgical field with an unobstructed view of the intradural VA, ipsilateral C1 and C2 roots, and spinal accessory nerve, as well as of the tumor matrix, without having the spinal cord in the way. In spite of the inability to obtain a watertight dural closure, the wound healed properly, although postoperative CSF drainage was required for some time.
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MENINGIOMA OF DIAPHRAGMA SELLAE Meningiomas arising from the hypophyseal tent are rare. Actually, fewer than 30 cases were collected in a recent review of the literature [23]. These authors proposed three types of diaphragma sellae meningioma, according to the actual site of attachment, whether anterior (Type A), posterior (Type B), or inferior to the pituitary stalk (Type C). In our case, the tumor could be classified as a Type A diaphragma sellae meningioma. Types A and B, as occurred in the present patient, can be confused preoperatively with the more common tuberculum sellae meningioma, which we usually approach using a bifrontal basal craniotomy as described by Samii [37]. In the present case, anatomical orientation was easily maintained, and the optic nerves as well as the internal carotid and anterior cerebral arteries were dissected from the tumor with relative ease. However, dissection of the posterior portion of the mass from the dorsum sellae and the posterior cerebral and basilar arteries was particularly demanding; the removal of part of the tumor matrix from behind the tuberculum sellae required some “blind” manoeuvres, which, however, were performed after all the important surrounding structures had been identified and properly protected. We did not consider it necessary to drill off the tuberculum sellae as advocated by Patterson [34], although this would have undoubtely offered an unobstructed view of the tumor attachment to the diaphragma sellae. Full view of the region of the hypophyseal tent may be obtained by removing the anterior clinoid as described by Dolenc [12]. However the choice of a lateral versus an anterior approach for treating parasellar meningiomas is a matter of great debate, and in most cases is left to the individual preference—and experience— of the operating surgeon, as both approaches have well-known advantages and shortcomings. ROLE OF PREVIOUS LOW-DOSE HEAD IRRADIATION IN THE ONCOGENESIS OF MENINGIOMAS Beginning in the late 1960s, several cases of meningioma occurring many years after low-dose therapeutic irradiation have been reported in literature [6,30,36,45,46]. In fact, before griseofulvin became available in 1959 [24], low-dose—approximately 800 R— head radiation according to the KienbockAdamson method [2,39] represented the therapeutic choice for children affected by tinea capitis. The latter seemed to show a peak of incidence in the difficult years during and immediately after the Sec-
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ond World War [29]. Low-dose irradiation was also freely administered in the past to children affected by other benign scalp conditions such as vascular nevus. Cases of intracranial meningioma occurring many years later in patients irradiated for this disease were reported [46]. Generally speaking, the pathogenetic role of low-dose radiation to the head in the oncogenesis of meningioma seems to be quite evident [36], in particular after statistical evidence of this was offered by large epidemiological follow-up studies of patients who had received radiation treatment for tinea capitis in childhood [29,44,45]. When compared with other meningiomas, radiation-induced tumors show several distinctive features including increased incidence of histological malignancy, tendency to recur, and calvarial location [36,45]. Multiplicity is also considered a relatively peculiar characteristic of post-irradiation meningiomas [36,45,46]. However, skull base location is actually rather uncommon in this group of tumors [36,45], which could be related to the fact that the path of irradiation in patients treated for tinea capitis would not significantly involve the region of the base of the skull. Accordingly, the role of previous irradiation to the head in the oncogenesis of the two meningiomas in the present patient might appear to be a matter of dispute. However, in the absence of the stigmata of Von Recklinghausen’s disease, we believe that the two remarkable clinical eveniences noted in the present case (i.e., therapeutic head irradiation during childhood and occurrence of multiple meningeal tumors later) would seem to be more than pure coincidence. Actually, it has been calculated that the base of the skull may receive as much as half of the dose to the calvarium when irradiated with the Kienbock-Adamson method [39, 45], theoretically still enough to influence the local mitotic activity [51]. It remains to be explained why head irradiation could have been the cause of meningeal tumors in uncommon locations in our patient, without inducing meningioma in other more commonly observed sites.
Conclusions In conclusion, this paper, by reporting a case of multiple meningioma occuring solely at the skull base, fills an existing gap in the literature. The actual role of previous head irradiation in the oncogenesis of the meningiomas in the present case remains somewhat unclear. Proper management strategy and judicious use of the techniques of skull
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base surgery were key factors in the successful treatment of our patient. REFERENCES 1. Abtahi H. Multiple meningiomas. Acta Neurochir 1975;31:279 (abstract). 2. Albert RE, Omran AR, Brauer EW, Dove DC, Cohen NC, Schmidt H, Baumring R, Morrill S, Schulz R, Baer RL. Follow-up study of patients treated by x-ray for tinea capitis. Am J Public Health 1966;56:2114 –20. 3. Al-Mefty O, Fox JL, Smith RR. Petrosal approach for petroclival meningiomas. Neurosurgery 1988;22:510 – 17. 4. Andrioli GC, Rigobello L, Iob I, Cosentini L. Multiple meningiomas. Neurochirurgia (Stuttg) 1981;24:67–9. 5. Bertalanffy H, Seeger W. The dorsolateral, suboccipital, transcondylar approach to the lower clivus and anterior portion of the craniocervical junction. Neurosurgery 1991;29:815–21. 6. Beller AJ, Feinsod M, Sahar A. The possible relationship between small dose irradiation to the scalp and intracranical meningiomas. Neurochirurgia (Stuttg) 1972;15:135– 43. 7. Bonnal J, Born JD, Tremoulet M. Meningiomes multiples intra-craniene. Neurochirurgie 1979;25:78 – 83. 8. Borovich B, Doron Y, Braun J, Feinsod M, Goldsher D, Gruszkiewicz J, Guilburd J N, Zaaroor M, Levi L, Soustiel J F, Lemberger A. The incidence of multiple meningiomas: do solitary meningiomas exist? Acta Neurochir 1988;90:15–22. 9. Butti G, Assietti R, Casalone R, Paoletti P. Multiple meningiomas: a clinical, surgical and cytogenetic analysis. Surg Neurol 1989;31:255– 6. 10. Cushing H, Eisenhardt L. Meningiomas: their classification, regional behavior, life history, and surgical end results. Springfield, Ill: Charles C Thomas, 1938: 100 –132. 11. Distelmaier P, Lins E, Kolberg T: Multiple meningiomas, two patients with a spinal and an intracranial meningioma, radiological diagnosis. Neurochirurgia 1976;19:114 –17. 12. Dolenc VV. A combined epi-and subdural direct approach to carotid-ophthalmic artery aneurysms. J Neurosurg 1985;62:667– 62. 13. Domenicucci M, Santoro A, D’Osvaldo DH, Delfini R, Cantore GP, Guidetti B. Multiple intracranial meningiomas. J Neurosurg 1989;70:41– 4. 14. Ekong CEU, Paine KWE, Rozdilsky B. Multiple meningiomas. Surg Neurol 1978;9:181– 4. 15. Federico F, D’Aprile P, Lorusso M, Carella A. Multiple meningiomas diagnosed by computed tomography. Ital J Neurol Sci 1984;5:295– 8. 16. Forthomme J (1986) Tumeurs de meninges. In: Delarue J, Laumonier R, eds. Anatomie pathologique, Vol 3. Flammarion, Paris pp 2255– 60. 17. Fukushima T. Combined supra-and infra-parapetrosal approach for petroclival lesions. In: Sekhar LN, Janecka IP, eds. Surgery of Cranial Base Tumors. New York, Raven Press, 1993:661–9. 18. George B, Dematons C, Cophignon J. Lateral approach to the anterior portion of the foramen magnum. Application to surgical removal of 14 benign tumors: technical note. Surg Neurol 1988;29:484 –90. 19. Geuna E, Pappado G, Regalia F, Arrigoni M. Multiple
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COMMENTARY
It is now well-established, on the basis of population incidence studies conducted in Israel, that craniospinal irradiation in childhood results in an increased incidence of meningiomas after a latency period of 10 years or more. We have observed a number of patients in our institution with multiple basal meningiomas and a prior history of cranial irradiation for tinea capitis, or cervical irradiation for goiter. Neurosurgical colleagues in Israel have also observed this phenomenon (F. Umansky and S. Pomeranz, personal communication, 1995). Some of these tumors show a more aggressive biological behavior than the average meningioma. The mechanism of tumor induction is by damage to the genetic material by the irradiation, with a loss of tumor suppressor genes. A relationship between the total radiation dose, the time course administration, and the latency period for the development of tumors has also been established. This phenomenon raises concerns about the use of radiosurgery for the treatment of benign tumors. However, there have been no studies to date linking radiosurgery and the occurrence of tumors in the central nervous system. Laligam N. Sekhar, M.D., FACS Department of Neurological Surgery George Washington University Washington, D.C.
Spallone A, Neroni M, Giuffre` R. Multiple skull base meningioma: case report. Surg Neurol 1999;51:274 – 80. BACKGROUND
The incidence of multiple skull base meningiomas varies from 1 to 3% in different series. Skull base meningiomas are rare. The pathogenetic role of low-dose radiation seems to be fairly well established in the oncogenesis of meningiomas. Calvarial location and multiplicity seem to be among the distinctive features of radiation-induced meningiomas. Skull base location is a very rare occurrence, mainly because the path of irradiation does not significantly involve this region. CASE REPORT
We describe a rare case of simultaneous occurrence of two skull base meningiomas in a 66-year-old female. This patient underwent low-dose irradiation for tinea capitis when she was 8 years old. The patient complained of nuchal pain, paresthesias in both hands, and progressive weakness on her right side. She was admitted to the hospital in September 1994. An MRI showed two masses, one located at the level of the tuberculum sellae and the other at the foramen magnum. These seemed very likely to be multiple meningiomas. The latter lesion, which was more symptomatic and dangerous, was operated on first. Six months later, elective treatment of the suprasellar meningioma was performed with success. CONCLUSION
The actual role of previous head irradiation in the oncogenesis of the present meningiomas remains somewhat unclear. Proper management and judicious use of skull base surgery techniques were key factors in the successful treatment of the patient. © 1999 by Elsevier Science Inc. KEY WORDS
Multiple meningioma, skull base, low-dose head irradiation, surgical treatment.
he multiplicity of meningioma has attracted the interest of the neurosurgical community because of its relative rarity, unclear etiology and the problems related to proper management strategy. The incidence of multiple skull base meningio-
T
Address reprint requests to: Dr. Aldo Spallone, M.D., Division of Neurosurgery, University “Tor Vergata,” Via Orazio Raimondo, 00173 Rome, Italy. Received March 12, 1996; accepted September 2, 1997. 0090-3019/99/$–see front matter PII S0090-3019(98)00087-1
mas varies from 1 to 3% in different series [1,15,19, 28,43,50]. As for the location of these meningiomas, the base of the skull is uncommon. Basal meningiomas were in fact observed in only 2 of the 14 patients harboring multiple meningiomas reported in a recent paper [13], a proportion that matches that of other published studies on multiple meningiomas [4,7,19,28,50]. We are reporting here a case of simultaneous occurrence of two meningiomas at the skull base, in the foramen magnum and in the diaphragma sellae respectively, in a woman who had received lowdose irradiation to her head many years ago. Lowdose irradiation is a recognized pathogenic factor for meningiomas in general and in particular for multiple meningiomas [36,45].
Case Report A 66-year-old woman was admitted to the hospital in September 1994. Her main complaints were nuchal pain, paresthesias in both hands, mainly on the right, and progressive weakness of her right side. The patient had had significant visual problems in the past, which had been related to hypertensive retinopathy. Her visual acuity had shown a steady decrease, mainly in her left eye, until being admitted to hospital. On examination she showed a moderate right side pyramidal weakness, with no obvious sensory or cranial nerve deficit. She had mild “piano playing finger” phenomenon in her right hand. Visual acuity was diminished to 4/50 in her left eye, and 4/10 in her right eye. A bitemporal hemianopsia was evident and a superior visual field cut was additionally present in the left eye. Computed tomography (CT) scanning showed a suprasellar mass that enhanced with contrast, as well as a lesion with similar characteristics located at the level of the foramen magnum. Selective cerebral angiography was limited to the study of the carotid system. This was attributable to the occur© 1999 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
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We decided to approach the foramen magnum lesion first as it appeared to exert significant pressure on the vital areas of the craniocervical junction and also seemed to show a definite tendency to worsen in the last months.
First Operation
MRI, sagittal (a) and axial (b) view after Gd-DTPAenhancement. An anterior foramen magnum meningioma (2.4 3 2 cm) is shown. The sagittal image (a) gives clear evidence of a 2.3 3 2.1 cm suprasellar mass with similar characteristics.
1
rence of symptoms of cerebrovascular insufficiency that occurred immediately after an attempt to catheterize the right vertebral artery. This subsided as soon as the catheter was removed. The examination showed a picture compatible with the presence of a suprasellar mass. Magnetic resonance imaging (MRI) (Figure 1, a– b), before and after gadolinium enhancement, showed two masses located at the level of the tuberculum sellae and the foramen magnum respectively, which seemed very likely to be multiple meningiomas. Just by chance we discovered that this patient had had irradiation for the treatment of tinea capitis when she was 8 years old. No other information regarding the treatment could be obtained.
Surgery was performed on September 16th, 1994. After a “horse shoe” incision that went from the midline to inferior to the left mastoid process, the extradural vertebral artery was identified at the transverse process of C2; then the greater occipital nerve was identified. The artery was carefully dissected from its groove and moved inferomedially, to expose the occipital condyle and the lateral mass of C1, which were partially drilled away. This exposed 1 cm of dura lateral to the point of entry of the vertebral artery. Dural opening was complicated by significant bleeding from a hypertrophic circular sinus, which was eventually controlled with extensive use of bipolar coagulation. Also for this reason the dural cut was limited laterally to the point of entry of the vertebral artery. As soon as the extradural bleeding was under control, tumor debulking was initiated. After reducing the tumor mass, which seemed to be rather poorly vascularized, it was dissected from the surrounding left C1 and C2 roots, the spinal accessory nerve, and the vertebral artery, with relative ease. The tumor matrix anterior and superior to the point of exit of the C1 root was adequately visualized without need for extending the dural cut laterally, and was extensively coagulated. Watertight dural closure could not be achieved. Postoperatively, lumbar drainage was maintained for 10 days, after which the patient was ambulant. Continuous lumbar CSF drainage was reapplied 3 days later, as the wound showed significant bulge. It disappeared a week later, with no further problems. Histology showed a meningothelial meningioma of fibroblastic variant (Figure 2).
Second Operation The same patient was readmitted for elective treatment of her suprasellar meningioma in March 1995. Postoperative MRI (Figure 3, a– b) had shown total removal of the craniospinal mass. The patient had demonstrated a definite improvement of her hemiparesis, but visual acuity appeared to be further diminished in the left eye (2/50). Visual evoked potentials were performed on admission to the hospital and showed a reduction of amplitude of the N75-P100 complex, as well as a marked increased
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atrophic. Removal of the tumor was continued with great care until the right posterior cerebral and basilar arteries came into view deep in the surgical field, after which the hypophyseal stalk was identified and spared, and the remaining tumor removed using curved instruments and bipolar coagulation. Some fragments had to be removed blindly from behind the hypertrophic tuberculum sellae.
MRI, sagittal (a) and coronal (b) view after enhancement obtained after the first operation. These images give evidence of the suprasellar meningioma, displacing the pituitary gland and its stalk downward. The foramen magnum meningioma is no longer present.
2
latency of the P100 potential. These data were compatible with a significant central visual pathway compression caused by the suprasellar mass. Surgery was performed in March 1995, using a bilateral frontobasal approach. A pericranial graft was fashioned to be used for reconstruction, and the sagittal sinus ligated proximally to allow division of the falx from the crista galli. The suprasellar mass was exposed after careful retraction of the frontal lobes and a full view of both carotid and anterior cerebral arteries, as well as of the compressed anterior optic pathways, was obtained. The mass was carefully debulked and devascularized at its bed, until the hypertrophic tuberculum sellae was reached. At this stage the reduced tumor mass could be safely dissected away from the surrounding vessels as well as from both optic nerves and the chiasm. The left optic nerve appeared to be flattened and
3
Control MRI. Sagittal (a) and axial (b– c) views show total removal of both masses.
Multiple Skull Base Meningiomas
Photomicrogram (H-E 3 100) shows hypocellular meningothelial meningioma constituted of wide collagen bands interspersed with neoplastic cells of elongated shape.
4
Hemostasis was checked, and the wound closed using the pericranial graft fashioned at the beginning of the operation. Postoperatively, visual acuity in the right eye improved significantly (from 4/10 to 7/10), as also did the hemianopsia. No significant improvement was noticed in the left eye. Postoperative MRI (Figure 4, a– b) demonstrated total removal of both masses. Histological examination showed a meningothelial meningioma with scattered psammomatous bodies (Figure 5).
Discussion MULTIPLE MENINGIOMAS Multiple meningiomas rarely occur at the base of the skull. The incidence of basal meningiomas out
Photomicrogram (H-E 3 50) of the second meningioma shows high cellularity with polymorphic lobules and syncytial features. Some lobules show cells of elongated shape immersed in wide collagen bands. Scattered psammomatous bodies were present.
5
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of the whole group of multiple meningiomas averaged 5% in a detailed recently published study [13]. It appeared to be slightly higher in another recent study [9]; however, it reported a smaller number of cases. A similarly low percentage of basal locations was generally observed in the relatively scanty literature on multiple meningiomas [1,4,7,10,14,19,26, 43,50], and did not seem to change in the more recently published reports in which CT scanning represented the chief diagnostic test, leading to higher diagnostic accuracy [15,27,28,31,35]. In these patients harboring multiple meningiomas, skull base tumors were, as a rule, observed in conjunction with the more frequently observed convexity or parasagittal-falx meningiomas. Simultaneous occurences of two intracranial meningiomas in two separate locations at the skull base is certainly a rare event, which to our knowledge has been mentioned in the literature only once before [40]. That patient was a 1-year-old child harboring a spinal meningioma in addition to a parasellar and a foramen magnum meningioma. HISTOLOGY OF MULTIPLE MENINGIOMAS Cushing and Eisenhardt [10] defined the condition of multiple meningiomas as one in which a patient has more that one meningioma but somewhat less than a dissemination of them. Multiple intracranial meningiomas were eventually separated into two groups [7,16]: 1. Distant multiple meningiomas (DMM), in which the lesions are located far from each other. 2. Regional multiple meningiomas (RMM), in which the lesions lie in close proximity. It has been speculated that multiple meningiomas may be actually multiple only when the lesions have a different morphology; they should be considered multicentric when the histologic pattern of the different lesions seems to be the same [8]. We found, surprisingly, that in the literature concerning multiple meningiomas, only a few papers report the histology of each surgically excised lesion [8,11,21, 22,32,40,49]. It seems from these papers that DMM show, as a rule, a different morphological pattern. This seems to be the case in our patient too; her tumors were located in separate regions, and exhibited different histological patterns. In fact, although both meningiomas could be classified as meningothelial, the presence of psammomatous bodies was a definite pattern in the lesion located in the suprasellar area, and clearly distinguished it from the meningioma operated on first.
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SKULL BASE MENINGIOMAS Craniobasal meningiomas have traditionally been considered very difficult to eradicate. The recent introduction of modern techniques of skull base surgery has definitely facilitated the removal of these lesions, by shortening the working distance, widening the surgical field, and minimizing the need for prolonged brain retraction [3,41]. This has changed the previous conservative attitude, and has resulted in widening the indications for curative surgery as well as in better results of operative management of these difficult lesions [3,17,33,38,41,47]. SURGICAL MANAGEMENT OF CRANIOSPINAL MENINGIOMAS Anteriorly located meningiomas at the craniocervical junction have represented a real surgical challenge when operated on using traditional approaches [20]. The recent introduction of the socalled extreme [5,18] or far [42] lateral approach to the craniovertebral junction has offered a definite contribution to facilitating the removal of these dangerous lesions. Mobilization of the vertebral artery (VA) and drilling of the occipital condyle has been advocated by some authors [42] to give an unobstructed view to the anterior dura, where these meningiomas may be attached. Others [18,25, 48] have argued that meningiomas in this location, although attached anteriorly, usually displace the spinal cord to one side, particularly if they have already attained a significant size. As a consequence of this, opening the dura laterally up to the point of entry of the VA, without going further laterally, should give enough space to expose the tumor matrix without the need for the brain substance to be retracted. In the present case, we operated on the more progressively symptomatic, thus, the more dangerous lesion, first. The extradural VA was carefully dissected and moved inferomedially, to drill off the lateral part of C1 and a portion of the medial occipital condyle. This exposed approximately 1 cm of the dura lateral to the point of entry of the VA. However, the dural opening, which was not extended so far laterally, was enough to obtain a wide surgical field with an unobstructed view of the intradural VA, ipsilateral C1 and C2 roots, and spinal accessory nerve, as well as of the tumor matrix, without having the spinal cord in the way. In spite of the inability to obtain a watertight dural closure, the wound healed properly, although postoperative CSF drainage was required for some time.
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MENINGIOMA OF DIAPHRAGMA SELLAE Meningiomas arising from the hypophyseal tent are rare. Actually, fewer than 30 cases were collected in a recent review of the literature [23]. These authors proposed three types of diaphragma sellae meningioma, according to the actual site of attachment, whether anterior (Type A), posterior (Type B), or inferior to the pituitary stalk (Type C). In our case, the tumor could be classified as a Type A diaphragma sellae meningioma. Types A and B, as occurred in the present patient, can be confused preoperatively with the more common tuberculum sellae meningioma, which we usually approach using a bifrontal basal craniotomy as described by Samii [37]. In the present case, anatomical orientation was easily maintained, and the optic nerves as well as the internal carotid and anterior cerebral arteries were dissected from the tumor with relative ease. However, dissection of the posterior portion of the mass from the dorsum sellae and the posterior cerebral and basilar arteries was particularly demanding; the removal of part of the tumor matrix from behind the tuberculum sellae required some “blind” manoeuvres, which, however, were performed after all the important surrounding structures had been identified and properly protected. We did not consider it necessary to drill off the tuberculum sellae as advocated by Patterson [34], although this would have undoubtely offered an unobstructed view of the tumor attachment to the diaphragma sellae. Full view of the region of the hypophyseal tent may be obtained by removing the anterior clinoid as described by Dolenc [12]. However the choice of a lateral versus an anterior approach for treating parasellar meningiomas is a matter of great debate, and in most cases is left to the individual preference—and experience— of the operating surgeon, as both approaches have well-known advantages and shortcomings. ROLE OF PREVIOUS LOW-DOSE HEAD IRRADIATION IN THE ONCOGENESIS OF MENINGIOMAS Beginning in the late 1960s, several cases of meningioma occurring many years after low-dose therapeutic irradiation have been reported in literature [6,30,36,45,46]. In fact, before griseofulvin became available in 1959 [24], low-dose—approximately 800 R— head radiation according to the KienbockAdamson method [2,39] represented the therapeutic choice for children affected by tinea capitis. The latter seemed to show a peak of incidence in the difficult years during and immediately after the Sec-
Multiple Skull Base Meningiomas
ond World War [29]. Low-dose irradiation was also freely administered in the past to children affected by other benign scalp conditions such as vascular nevus. Cases of intracranial meningioma occurring many years later in patients irradiated for this disease were reported [46]. Generally speaking, the pathogenetic role of low-dose radiation to the head in the oncogenesis of meningioma seems to be quite evident [36], in particular after statistical evidence of this was offered by large epidemiological follow-up studies of patients who had received radiation treatment for tinea capitis in childhood [29,44,45]. When compared with other meningiomas, radiation-induced tumors show several distinctive features including increased incidence of histological malignancy, tendency to recur, and calvarial location [36,45]. Multiplicity is also considered a relatively peculiar characteristic of post-irradiation meningiomas [36,45,46]. However, skull base location is actually rather uncommon in this group of tumors [36,45], which could be related to the fact that the path of irradiation in patients treated for tinea capitis would not significantly involve the region of the base of the skull. Accordingly, the role of previous irradiation to the head in the oncogenesis of the two meningiomas in the present patient might appear to be a matter of dispute. However, in the absence of the stigmata of Von Recklinghausen’s disease, we believe that the two remarkable clinical eveniences noted in the present case (i.e., therapeutic head irradiation during childhood and occurrence of multiple meningeal tumors later) would seem to be more than pure coincidence. Actually, it has been calculated that the base of the skull may receive as much as half of the dose to the calvarium when irradiated with the Kienbock-Adamson method [39, 45], theoretically still enough to influence the local mitotic activity [51]. It remains to be explained why head irradiation could have been the cause of meningeal tumors in uncommon locations in our patient, without inducing meningioma in other more commonly observed sites.
Conclusions In conclusion, this paper, by reporting a case of multiple meningioma occuring solely at the skull base, fills an existing gap in the literature. The actual role of previous head irradiation in the oncogenesis of the meningiomas in the present case remains somewhat unclear. Proper management strategy and judicious use of the techniques of skull
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COMMENTARY
It is now well-established, on the basis of population incidence studies conducted in Israel, that craniospinal irradiation in childhood results in an increased incidence of meningiomas after a latency period of 10 years or more. We have observed a number of patients in our institution with multiple basal meningiomas and a prior history of cranial irradiation for tinea capitis, or cervical irradiation for goiter. Neurosurgical colleagues in Israel have also observed this phenomenon (F. Umansky and S. Pomeranz, personal communication, 1995). Some of these tumors show a more aggressive biological behavior than the average meningioma. The mechanism of tumor induction is by damage to the genetic material by the irradiation, with a loss of tumor suppressor genes. A relationship between the total radiation dose, the time course administration, and the latency period for the development of tumors has also been established. This phenomenon raises concerns about the use of radiosurgery for the treatment of benign tumors. However, there have been no studies to date linking radiosurgery and the occurrence of tumors in the central nervous system. Laligam N. Sekhar, M.D., FACS Department of Neurological Surgery George Washington University Washington, D.C.