Extramedullary foramen magnum tumors and their surgical management: An experience with 29 cases

Abstract

Introduction: Surgical management of foramen magnum (FM) tumors is challenging by virtue of their location and vital neurovascular relationships. The ideal approach to anterior/anterolateral tumors continue to evoke controversy even in the modern era. In this article, we present and discuss our experience in the surgical management of these tumors.

Materials and methods: This retrospective study includes 29 consecutive patients (mean age 36.6 years, M: F = 2.63:1) of extramedullary tumors at the surgical foramen magnum, operated at our center, between 2007 and 2012.

Results: Their mean duration of symptoms was 14. 6 months. A majority of the patients presented with motor symptoms (quadri/paraparesis, n = 21, 72.4%), neck pain with/without suboccipital radiation (n = 16, 55.2%) and sensory symptoms like tingling/numbness (n = 16, 55.2%). There were nine extradural (31%) and 20 intradural tumors (69%). Most of the tumors were located posterolateral to the neuraxis (n = 13, 44.8%). Nerve sheath tumors (n = 11, 38%) and meningiomas (n = 5, 17.2%) were the most commonly encountered histologies in our series. The standard posterior approach was the most frequently employed surgical approach (n = 20, 69%). Operative mortality and morbidity were 3.4 and 18.9%, respectively. At a mean follow-up of 27.3 months, 13 out of the 18 available patients improved.

Conclusion: A majority of the foramen magnum tumors are amenable to excision via the standard posterior approach. Small anterior dural-based meningiomas/recurrent tumors may require a lateral approach like the far lateral approach.

Keywords: Extramedullary; foramen magnum tumors; pathology; surgical approach.

Figure 1

(a) T2 sagittal image shows a ventrally located iso-to slightly hyperintense mass at the foramen magnum without any cord intensity changes. On contrast administration, it shows homogenous and uniform enhancement on contrast administration with a dural tail sign; (b) Axial contrast MRI shows a ventrolateral location of the mass with displacement of the cord posterolaterally toward the left; (c) Figure 1d and e show postoperative CT images with complete excision of the mass and bony exposure done during surgery

Figure 2

Sagittal (a and b) and coronal (c) MRI sections show a T1 hypointense and T2 hyperintense anteriorly placed intradural foramen magnum mass, with altered intensity at the center. Postoperative sagittal T2WI shows complete tumor excision; (d) The H and E stained section (200X) shows a cyst wall, lined by a columnar and focal mucinous epithelium resting on the subepithelial fibrocollagenous tissue (e) Suggestive of a neuroenteric cyst