© Springer International Publishing AG 2018 135
W.T. Couldwell (ed.), Skull Base Surgery of the Posterior Fossa,
https://doi.org/10.1007/978-3-319-67038-6_10
Foramen Magnum Meningiomas
Angela M. Richardson, Karolyn Au,
and Jacques Morcos
A.M. Richardson, MD, PhD • K. Au, MD, MSc
J. Morcos, MD, FRCS(Eng), FRCS(Ed), FAANS (*)
Department of Neurological Surgery, University of
Miami/Jackson Memorial Hospital, Miami, FL, USA
e-mail: [email protected]
10
Introduction
Foramen magnum meningiomas (FMMs) are a
rare entity; they account for 2.5% of all intracra-
nial meningiomas and 4% of posterior fossa
meningiomas [ 22 ]. The pathologic entity of FMM
was first described in 1872; the first publication
describing surgical removal was in 1922 [ 10 ].
That same year Cushing described a nomenclature
for these lesions and published his series. The
location of these lesions at the craniocervical junc-
tion in proximity to, and possibly encasing, the
lower cranial nerves or vertebral arteries makes
successful removal particularly challenging [ 14 ,
20 ]. A meningioma is considered to arise from the
foramen magnum if the insertion of the tumor is in
the region bounded anteriorly by the lower third of
the clivus and the upper edge of the body of C2,
laterally by the jugular tubercles and the upper
aspect of the C1 laminas, and posteriorly by the
anterior edge of the squamous occipital bone and
C2 spinous process [ 8 ]. The large majority (90%)
of these tumors are located ventrally or ventrolat-
erally requiring a lateral or anterior trajectory for
successful surgical removal [ 8 , 21 , 23 ].
Clinical Presentation
FMMs are typically slow growing with an indo-
lent course, but when they become symptomatic,
they most commonly present with quadriparesis,
sensory abnormalities, ataxia, and dysfunction
of cranial nerves (CN) IX and X [ 22 ]. Patients
often describe suboccipital headache or upper
cervical pain, exacerbated by coughing or strain-
ing [ 10 ]. The vague nature of symptoms often
prevents early diagnosis with a mean of
31 months to diagnosis from symptom onset [ 7 ].
The classic presentation of weakness associated
with a FMM is initial weakness in the ipsilateral
arm. Progression then occurs to the ipsilateral
leg, then the contralateral leg, and finally the
contralateral arm [ 7 ]. With compression at the
craniocervical junction, patients may also have
downbeat nystagmus on physical exam. Other
signs that may be present include wasting of the
sternocleidomastoid, trapezius, or intrinsic mus-
cles of the hands [ 10 ].Evolution of Surgical Approach
to FMM
A suboccipital craniotomy with drilling of the
condyle/jugular tubercle was initially described
for resection of craniospinal lesions in 1978 [ 22 ].
Heros then described the far-lateral approach