Mirror Meningioma at Foramen Magnum: A Management Challenge

Accepted Manuscript Mirror Meningioma at Foramen Magnum: A management challenge Subhas Konar, MD, MCh, Shyamal C. Bir, MD, PhD, FAHA, Tanmoy Kumar Maiti, MD, MCh, Piyush Kalakoti, MD, Anil Nanda, MD, MPH, FACS PII:

S1878-8750(15)01020-7

DOI:

10.1016/j.wneu.2015.08.006

Reference:

WNEU 3109

To appear in:

World Neurosurgery

Received Date: 23 June 2015 Revised Date:

31 July 2015

Accepted Date: 1 August 2015

Please cite this article as: Konar S, Bir SC, Maiti TK, Kalakoti P, Nanda A, Mirror Meningioma at Foramen Magnum: A management challenge, World Neurosurgery (2015), doi: 10.1016/ j.wneu.2015.08.006. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Mirror Meningioma at Foramen Magnum: A

management challenge

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Subhas Konar MD, MCh, Shyamal C. Bir MD, PhD, FAHA, Tanmoy Kumar Maiti MD, MCh, Piyush Kalakoti MD and Anil Nanda MD, MPH, FACS

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Department of Neurosurgery, LSU Health-Shreveport, 1501 Kings Highway, Shreveport,

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LA 71130-3932, USA

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Correspondence

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Anil Nanda MD, MPH, FACS

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Professor and Chairman,

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Department of Neurosurgery,

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LSU Health-Shreveport,

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1501 Kings Highway,

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Shreveport, LA 71130-3932, USA

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Tel:318-675-6404, Fax: 318-675-6867

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E-mail: [email protected]

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Abbreviations VA: Vertebral Artery GKRS: Gamma Knife Radiosurgery

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FMMs: Foramen Magnum Meningiomas

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CT: Computer Tomography

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MRI: Magnetic Resonance Imaging

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Abstract

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Background

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Meningiomas of foramen magnum are among the most challenging of all skull base

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lesions. Controversies continue regarding the most appropriate approach to this critical

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anatomical region. The authors report a first case in English literature about twin

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meningioma arising from both sides of ventrolateral dura at Forman magnum.

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Case description

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Preoperative imaging showed

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intra-operatively

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artery (VA) and abutted the left side. The unilateral far lateral transcondylar approach is

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not enough to resect both tumors at the

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transcondylar approach in both sides may compromise the stability as well as increase

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the risk of injury to either side of the neurovascular structures.

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Conclusions

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We suggest that resection can be safely achieved via the unilateral far lateral

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transcondylar approach followed by Gamma Knife Radiosurgery (GKRS) or a staged

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bilateral approach.

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twin mass was discovered that encased the right side vertebral

same time. However, , the far lateral

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a solitary mass engulfing the lower medulla. However,

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Introduction:

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Foramen magnum meningiomas (FMMs) account for 2.5% of all intracranial

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meningiomas; 90 % are located ventrally and ventrolaterally

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involves the foramen magnum has a notoriously insidious clinical course. Such a

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prolonged and often relapsing and remitting presentation explains the 30.8 months

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mean length of symptoms prior to diagnosis, even in this era of advanced

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neuroimaging.2 Optimal surgical planning for resection of

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meningioma should include dedicated high-resolution, thin-slice computer tomography

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(CT) of the cranio-cervical junction to delineate bone margins and estimate the size of

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the surgical corridor. Magnetic resonance imaging (MRI) with Gadolinium contrast study

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to demonstrate the dural attachment as well as the tumor vertebral relationship and

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Diffusion Tensor imaging with tractography study to help in assessing the distortion of

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important

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approached from posterior, posterolateral, and anterior directions.

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The focus of this article is to draw attention to

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ventrolateral meningioma in the foramen magnum and the difficulties in managing the

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surgical challenge.

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Case report:

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Following a motor vehicle accident, a 59 year old female developed persistent left neck

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pain and stiffness. . There was no history of radiation, motor weakness, bladder or

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bowel involvement, or gait disturbance. The patient was referred for physiotherapy for

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three weeks until imaging was ordered. No abnormality was detected on physical

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examination except neck stiffness. MRI cervical spine (figure 1) revealed a solitary

Meningioma that

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the foramen magnum

the rare occurrence of bilateral

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tracts in the spinal cord. Foramen magnum meningiomas can be

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mass along the anterior margin of foramen magnum with an enhancing dural tail

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extending both superiorly and inferiorly. The mass measured 3 cm (cranio-caudal) with

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dural tail x1.4 cm (anterior-posterior) x 2 cm (width). The mass encased the right

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vertebral artery and abutted the medial margin of left vertebral artery. The CT scan also

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revealed enhancement along with calcification. A diagnosis of cranio-cervical mass

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lesion was made and resection was planned. The patient

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lateral craniotomy and drilling of occipital condyle. The tumor was vascular and densely

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adhered to

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of tumor, an encapsulated separate mass was noted with different dural attachment

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(figure 2). Since

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done in piecemeal manner and the dura was closed. Given the intra-operative findings,

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further review of the pre-operative MR images showed two mirror lesions. On the right

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side

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(craniocaudal). On the left side, it was 10 mm (anterior-posterior) x 8 mm (width) x 15

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mm (craniocaudal), (figures 3A and B) with separate origin from the dura with a clear

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plane in midline. (Figure 3A) On histology, the section of tumor mass confirmed the

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diagnosis of meningothelial meningioma (figure 3C). Postoperative period was

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underwent right sided far-

the mass

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the right vertebral artery. However, during the resection of the medial part

abutted the left vertebral artery, gross total resection was

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the lesion was 12 mm (anterior-posterior) x 12 mm (width) x 30 mm

uneventful and the patient was discharged on post op day 10.

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Discussion:

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Foramen magnum meningiomas are slow growing benign tumors that poses significant

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challenges to the skull base neurosurgeons. George et al4 classified foramen magnum

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meningiomas into three groups according to their zone of origin and used anterior, 5

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lateral and posterior approaches to excise foramen magnum lesions. Ventral and

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ventrolateral foramen magnum meningiomas are the most challenging surgical group

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among meningiomas of this region. Arnautovic et al1 reported that ventrally located

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foramen magnum meningiomas comprise 68%–98% of the total and suggested that

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these lesions are different in their symptomatology, neurological findings, operative

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approach, postoperative results, complications and mortality rates. Concerning the

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location, the relationships with the vertebral artery (VA) and the dura are also important

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to evaluate before surgery. In our case, the mass encased the right vertebral artery and

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abutted the medial margin of left vertebral artery.

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The surgical treatment of FMMs has evolved considerably over the last four decades

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due to the progress in microsurgical techniques and the development of a multitude of

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skull base approaches. The far-lateral approach with or without condylar drilling

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provides exposure of the upper ventral spinal canal, anterior portion of the foramen

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magnum, lower and middle clivus and the jugular foramen. However, controversy still

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exists regarding the optimal management of anterior or anterolateral lesions. George et

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al3 reported on one of the largest series of patients who underwent the transcondylar

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approach to the foramen magnum in which the morbidity rate was low. The far-lateral

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approach without resection of the occipital condyle has reportedly been used

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successfully to treat vascular lesions by Heros.5 Samii et al

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total removal of meningiomas in this location, which was mainly achieved using the

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lateral suboccipital approach. In contrast, Salas and associates11 achieved 66% total

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removal by using more aggressive transcondylar approaches in 24 patients with

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meningiomas of the foramen magnum. In a recent study, Arnautovic, et al

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reported a 63% rate of

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achieved a

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75% total removal rate in 18 patients who harbored meningiomas of the anterior

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foramen magnum. Nanda et al

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resection rate with low risks of morbidity and mortality in the foramen magnum

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meningioma. . In our patient since

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approached through right side far- lateral with condylar drilling. However, during surgery

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it was

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and distinguished capsule. The significant adherence to the left VA prohibited us from

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resecting this tumor in the same sitting.

reported on a

“no drill” technique to achieve good

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the tumor was encased the right VA, it was

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revealed that the left sided tumor was separate with different dural attachment

Only two case reports of bilateral ventrolateral mass at forman magnum with surgical

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management have been reported in the English literature. Liu et al

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bilateral dumbbell C1 neurofibroma and showed excision via unilateral modified far

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lateral approach. Later, Patel et al

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neurenteric cysts in a child and approached it via staged far lateral approach in both

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sides. However, in our case pathology was different and it was a dural base tumor with

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bilateral VA adherence, so bilateral staged far lateral approach with condyle drilling or

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unilateral modified far lateral approach would have

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craniovertebral junction and risked VA injury.

reported bilateral cervicomedullary junction

comprised the stability of

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reported a case of

Complete resection rates have varied from 0% to 100%, while recurrence rates have

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varied from 0% to 33% in surgical series published in the last two decades.16 Factors

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associated with incomplete resections and recurrences include encasement of the

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vertebral arteries,12 tumor invasiveness (as evident from the extradural component of

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the tumors), 4,7,13 and adherences to vital structures especially in recurrent lesions.1,12 At

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the time of this review, we found only three studies specifically addressing the

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management of FMMs with radiosurgery via the Gamma Knife

Muthukumar et al

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in four patients. Likewise, Starke et al

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one case and no growth in four cases. Zenonos et al

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in which twelve patients had primary symptomatic tumors, five had asymptomatic but

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enlarging primary tumors, and seven had recurrent or residual tumors after a prior

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surgery. Ten patients had measurable tumor regression, which was defined as an

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overall volume reduction more than 25%, eleven patients had no further tumor growth,

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and

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had been given a choice between GKRS for the residual tumor or staged surgery.

reported five cases of FMMs with tumor reduction in one case and no further growth reported five cases of FMMs with reduction in published 24 cases of FMMs

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two patients died as a result of advanced comorbidities. In our case, the patient

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Conclusion:

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We report the first case of incidental bilateral ventrolateral foramen magnum

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meningioma. Resection can be safely and adequately achieved via the unilateral far-

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lateral approach followed by GKRS or

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Although complete excision of the tumor is the goal of surgery, it is safer to leave

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portions of tumor that are adherent to critical structures.

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the staged bilateral far lateral approach.

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References:

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7. 8. 9.

10. 11.

12. 13. 14. 15.

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Arnautovic KI, Al-Mefty O, Husain M: Ventral foramen magnum meninigiomas. J Neurosurg 92:71-80, 2000 Boulton MR, Cusimano MD: Foramen magnum meningiomas: concepts, classifications, and nuances. Neurosurg Focus 14:e10, 2003 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 29:484-490, 1988 George B, Lot G, Boissonnet H: Meningioma of the foramen magnum: a series of 40 cases. Surg Neurol 47:371-379, 1997 Heros RC: Lateral suboccipital approach for vertebral and vertebrobasilar artery lesions. J Neurosurg 64:559-562, 1986 Liu J, Chakrabarti I, Mcdermott M W. (2014-11-16 17:21:40 UTC) Resection of Bilateral C1 Neurofibromas Using a Unilateral Modified Far-Lateral Approach . . Cureus 6:227, 2014 Kratimenos GP, Crockard HA: The far lateral approach for ventrally placed foramen magnum and upper cervical spine tumours. Br J Neurosurg 7:129-140, 1993 Muthukumar N, Kondziolka D, Lunsford LD, Flickinger JC: Stereotactic radiosurgery for anterior foramen magnum meningiomas. Surg Neurol 51:268-273, 1999 Nanda A, Vincent DA, Vannemreddy PS, Baskaya MK, Chanda A: Far-lateral approach to intradural lesions of the foramen magnum without resection of the occipital condyle. J Neurosurg 96:302-309, 2002 Patel SK, Liu JK: Staged bilateral far-lateral approach for bilateral cervicomedullary junction neurenteric cysts in a 10-year-old girl. J Neurosurg Pediatr 12:274-280, 2013 Salas E, Sekhar LN, Ziyal IM, Caputy AJ, Wright DC: Variations of the extreme-lateral craniocervical approach: anatomical study and clinical analysis of 69 patients. J Neurosurg 90:206-219, 1999 Samii M, Klekamp J, Carvalho G: Surgical results for meningiomas of the craniocervical junction. Neurosurgery 39:1086-1094; discussion 1094-1085, 1996 Sen CN, Sekhar LN: An extreme lateral approach to intradural lesions of the cervical spine and foramen magnum. Neurosurgery 27:197-204, 1990 Starke RM, Nguyen JH, Reames DL, Rainey J, Sheehan JP: Gamma knife radiosurgery of meningiomas involving the foramen magnum. J Craniovertebr Junction Spine 1:23-28, 2010 Talacchi A, Biroli A, Soda C, Masotto B, Bricolo A: Surgical management of ventral and ventrolateral foramen magnum meningiomas: report on a 64-case series and review of the literature. Neurosurg Rev 35:359-367; discussion 367-358, 2012 Zenonos G, Kondziolka D, Flickinger JC, Gardner P, Lunsford LD: Gamma Knife surgery in the treatment paradigm for foramen magnum meningiomas. J Neurosurg 117:864-873, 2012

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Figure and video legends:

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Figure 1: Pre-operative images: A: CECT (Axial): Solitary enhancing mass lesion at

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foramen magnum; B: MRI with Contrast (Axial) : Single bi-lobed mass ,encasing both

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vertebral arteries ; C: MRI (T2W,Saggital): isointense mass with splaying of both

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Vertebral arteries.

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Figure 2: Intra-operative images: A: Right side tumor with mass effect on nerve roots; B:

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Post resection with lax nerve roots; LCN: Lower cranial nerves; SC: Spinal Cord; C: Left

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side tumor with intact capsule.

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Figure 3: Retrospective review of pre-operative image revealed the mirror meningioma

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(A) and (B) post-operative image showing resection right sided meningioma with a left

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sided tumor at foramen magnum. (C) Histopathological findings: Section of tumor mass

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shows meningiothelial character of meningioma.

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Video: Intraoperative features and technique of excision of foramen magnum

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meningioma. After opening of the dura, right side tumor was encountered which was

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gently separated from the lower cranial nerves and C1 rootlets. At the end of excision of

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right side tumor, a separate capsule was noted which had a venterolateral dural origin

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on the left side.

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Highlights 1. Meningiomas of foramen magnum are among the most challenging of all skull

base lesions. 2. Authors report a first case in English literature about twin meningioma arising

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from both sides of ventrolateral dura at Forman magnum.

3. We suggest resection can be safely achieved via unilateral far-lateral

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transcondylar approach followed by Gamma Knife Radiosurgery (GKRS) or a staged bilateral approach

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Abbreviations VA: Vertebral Artery

FMMs: Foramen Magnum Meningiomas

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CT: Computer Tomography

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GKRS: Gamma Knife Radiosurgery

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MRI: Magnetic Resonance Imaging