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a
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Fig. 59.1 Macroscopic
appearance of a nerve
sheath tumor. (a)
schwannoma—the tumor is
displacing normal fascicles
to the periphery; (b)
neurobroma—the tumor
appears as fusiform
dilatation of the nerve.
Surgical preservation of
the nerve is usually not
possible
b
M. Ivanov and I. Poeata
intact. Neurobromas appear as diffuse fusiform enlargement of the nerve
(Fig.59.1).
Histologically schwannomas have densely packed Antoni A areas in conjunctions with Antoni B areas and do not have cytologic atypia, which differentiates
them from neurobromas.
59.2 Natural History
The benign NST may remain dormant for many years. However, the tumor may
continue to slowly grow. If untreated, they may cause initially some intermittent
irritation and subsequently compression of the transiting neural structures inside the
spinal canal with resulting symptoms of spinal cord or nerve root compression.
When growing outside the spinal canal, the tumor may reach impressive size before
becoming symptomatic [1].
In approximately 2% to 6% of cases, the tumors may suffer malignant transformation. This risk is much higher in patients with neurobromatosis (NF-1)—
up to 50%.
59.3 Physical Examination
The symptoms in patients with NST may result initially from the nerve root affected
by the tumor. With tumor progression, it may compress other-transiting neural
structures and the patients may develop symptoms from compression of the bypassing nerve roots or spinal cord.
Clinical examination should look for signs of the spinal cord or nerve compression with an assessment of gait, muscle power, sensation, reexes, plantars, sphincters and Romberg probe (Video 59.4).
59 Spinal Nerve Sheath Tumors (NST): Schwannoma andNeurobroma
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a
b
Fig. 59.2 (a) Intraoperative image demonstrating cystic nerve sheath tumor arising from the
nerve root which is otherwise intact. (b) Left—direct intraoperative nerve root stimulation.
Right—image after excision of the tumor with preservation of the integrity of the nerve root
In addition to detailed neurological examination (Videos 59.4 and 59.9), the doctor should perform a careful inspection with the assessment of signs of NF-1 (café
au lait skin lesions, skin neurobromas, spinal deformity, axial or inguinal freckles,
hamartomas of the iris) (Chap. 23).
59.4 Imaging
Magnetic resonance imaging (MRI) scan is the method of choice for diagnosis of
spinal NST, which appear as roundish lesions, located either entirely inside the spinal canal or extending into neural foramina as well outside the spinal canal.
On T1-WI and T2-WI, they usually have intensity similar to spinal cord and
show moderate gadolinium enhancement. The tumors sometimes may have a cystic component, which is hypointense. Cystic tumors are more common in the
lumbar spine and can be easily missed if the tumor wall is thin (Figs. 59.2
and 59.3).
Computed tomography (CT) scan may show bone remodeling. Myelo-CT can be
an alternative imaging technique when an MRI scan is contraindicated; however, it
will demonstrate only intradural tumor component.
It is recommended to scan the whole neuraxis and rule out other lesions.
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Fig. 59.3 MRI and intraoperative characteristic of the nerve sheath tumors
59.5 Differential Diagnosis
M. Ivanov and I. Poeata
Other lesions that should be considered are meningiomas (Chap. 58), myxopapillary ependymomas (Chap. 60), and dermoid/epidermoid tumors. Cystic tumors
should be differentiated from the arachnoid cysts (Video 59.8).
Nerve sheath tumor, when compared to meningiomas, showed a signicantly
higher frequency of cystic change (96% vs. 24%), neural foraminal extension (29%
vs. 3%), and lumbar location (41% vs. 5%) [2].
59.6 Treatment Options
NST can be incidental ndings. If completely asymptomatic, it is reasonable to keep
them under surveillance. The tumor may remain dormant for decades; however,
malignant transformation is possible.
In patients with signicant or progressive symptoms, surgical resection is
recommended.
After dural opening, the surgeon can see tumor arising from one nerve root. The
tumor is generally mobile and not attached to dura. The transiting nerve roots or
spinal cord appears displaced. If the spinal cord is severely compressed, the tumor
can be initially debulked before manipulating it (not always necessary). The proximal and distal poles of the tumor should be identied.
We recommend the use of intraoperative neurophysiological monitoring with
direct nerve stimulation (Fig.59.2b). It can help to conrm whether the affected
59 Spinal Nerve Sheath Tumors (NST): Schwannoma andNeurobroma
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nerve is still functional. In case of positive motor response on direct nerve root
stimulation, the effort should be made to preserve its integrity. Careful microscopic
inspection can help to identify the thinned and unaffected by the tumor neural lets
on the surface/capsule of the tumor. With microscopic dissection, these lets can be
separated from the capsule with preservation of their anatomical integrity
(Fig.59.2b).
When located in proximity to the spinal cord, the tumor may originate from the
nerve root entry zone and may have intramedullary extension, which adds to the
complexity of surgery.
In case of a dumbbell tumor, the surgery is more challenging. The challenges
result from:
(a) Large dural defect that needs to be repaired.
(b) Need of removal of the intra- and extraspinal components, which may require
two separate procedures.
(c) Need for spinal stabilization in case of excessive bone removal.
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59.7 Expected Outcomes
The outcome after removal of a solitary nerve sheath tumor is usually good. The
symptoms from compression of transiting neural structures would normally
improve.
Due to slow tumor growth, the function of the affected nerve root frequently is
taken by other nerve roots (functional reorganization), and in many patients with
dumbbell tumors, transection of the affected nerve root does not always produce a
new postoperative decit.
Some new neurological decit is nevertheless possible. As the tumor is arising
predominantly from the sensory lets, 30% of patients may have new postoperative
sensory decit (usually well tolerated) and 5% new motor decit [3].
Long-term follow-up reveals that 20% of patients considered themselves free of
symptoms. The most common late complaint was local pain (46%), followed by
radiating pain (43%), paraparesis (31%), and radicular decit (28%) [4].
The recurrence rate is low, but possible therefore surveillance MRI scan is recommended [4].
59.8 Potential Complications
Surgery may cause the new neurologic decit, CSF leak, infection, and bleeding.
Transection of the T8-T12 nerve roots may lead to abdominal hernia.
In the late stages, the patients may develop spinal deformities such as scoliosis
and kyphoscoliosis (6%), spinal arachnoiditis (6%), and persisting local or referring
pain [4].
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M. Ivanov and I. Poeata
59.9 What Should Patient andFamily Know?
When the tumor is asymptomatic or minimally symptomatic, it is reasonable to
keep it under surveillance. The tumor may remain unchanged for decades or the rest
of life; however, a small risk of malignant transformation exists.
The surgery is recommended in symptomatic patients or if the surveillance imaging shows tumour progression. The goal of surgery is to prevent further neurological
decline. It can help to relieve symptoms from compression of the transiting neural
structures; however, due to potential need to sacrice one of the nerve roots, new
postoperative decit is possible.
Further Readings
1. Lee MT, Panbehchi S, Sinha P, Rao J, Chiverton N, Ivanov M. Giant spinal nerve sheath
tumours—surgical challenges: case series and literature review. Br J Neurosurg. 2019;33:541–9.
2. Lee JH, Kim HS, Yoon YC, Cha MJ, Lee SH, Kim ES.Differentiating between spinal schwan-
nomas and meningiomas using MRI: a focus on cystic change. PLoS One. 2020;15:e0233623.
3. Safaee MM, Lyon R, Barbaro NM, Chou D, Mummaneni PV, Weinstein PR, Chin CT, Tihan
T, Ames CP.Neurological outcomes and surgical complications in 221 spinal nerve sheath
tumors. J Neurosurg Spine. 2017;26:103–11.
4. Seppala MT, Haltia MJ, Sankila RJ, Jaaskelainen JE, Heiskanen O. Long-term outcome
after removal of spinal schwannoma: a clinicopathological study of 187 cases. J Neurosurg.
1995;83:621–6.
Spinal Ependymoma
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60
PeterTruckenmueller, RubenKnappe, JuliaOnken,
andPeterVajkoczy
60.1 Definition
Ependymomas are rare glial tumors that arise from ependymal cells, which form the
lining of the ventricles of the brain and the central canal in the spinal cord. Spinal
ependymomas usually affect adults, with an incidence of 0.21 per 100,000, whereas
intracranial ependymomas mostly develop in children.
60.2 Natural History
The median age of diagnosis is mainly reported as mid-40s ±15 years and a slight
predominance in males with a male/female rate of 1.15. Histologically, ependymomas are classied in WHO grades I–III, with grade II being the most common in the
spine. With 60%, spinal ependymoma represent the most common intramedullary
tumor and are mostly of tanycytic histological type. They can also arise from the
terminal thread (lum terminale), associated with the histological type of myxopapillary ependymomas, which account for 90% of tumors in this location (Table60.1).
Supplementary Information The online version contains supplementary material available at
(https://doi.org/10.1007/978- 3- 030- 80356- 8_60).
P. Truckenmueller · R. Knappe · J. Onken · P. Vajkoczy (*)
Department of Neurosurgery and Pediatric Neurosurgery, Charité - Universitätsmedizin,
Berlin, Germany
e-mail: peter.vajkoczy@charite.de
© The Author(s), under exclusive license to Springer Nature
Switzerland AG 2022
A. Şenköylü, F. Canavese (eds.), Essentials of Spıne Surgery,
https://doi.org/10.1007/978-3-030-80356-8_60
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Table 60.1 Distribution of location of spinal ependymoma
Location in the spine
Cervical 35%
Thoracic 21%
Lumbar 69%
Intramedullary 64%
Extramedullary or lum 36%
P. Truckenmueller et al.
They present as intradural, extramedullary lesions; however, by denition, they are
intramedullary lesions, as they arise from the central canal, too.
An important characteristic of ependymoma is the possibility of leptomeningeal
drop metastasis. In children, ependymomas primarily manifest intracranially,
although leptomeningeal drop metastasis can occur in the spine. Therefore, contrastenhanced magnetic resonance imaging (MRI) of the brain and the whole spine is the
gold standard for the diagnosis of intraspinal tumors. Additionally, at least two lumbar punctures and cerebrospinal uid (CSF) examinations for drop metastasis are
advised.
60.3 Physical Examination
Overall, cervical and lumbar are the most common locations of spinal ependymoma,
and symptoms are primarily determined by the location, possibly leading to sensorimotor decits, impairment of coordination and/or vegetative symptoms, such as
bladder and bowel dysfunction. Clinically, spinal ependymoma often presents as
incomplete paraparesis, although pain, sensory and motor impairment can also
occur in a radicular pattern when nerve roots are affected. Thus, a thorough neurological exam should be performed, consisting of motor function tests, sensory evaluation, straight leg raise, Romberg’s test, heel-knee test, and digital rectal exam
(Video 60.4).
60.4 Imaging
On spinal MRI, ependymomas show a homogeneous contrast enhancement on the
T1 sequence. Intramedullary manifestations typically cause symmetric widening of
the spinal cord. Syringohydromyelia can be present. In the T2 sequence, the socalled cap sign, hypointense hemosiderin areas adjacent to the lesion caused by
hemorrhage, are suggestive of ependymoma (Figs.60.1, 60.2, and 60.3).
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Fig. 60.1 MRI T1
sequence post-contrast of
the lumbar spine in sagittal
view: a white arrow
pointing at a
myxopapillary
ependymoma in the lumbar
spine, on level of lumbar
vertebrae 2–3in a
31-year-old female
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Fig. 60.2 MRI T1
sequence post-contrast in
axial view on the level of
lumbar vertebrae L2–3:
Myxopapillary
ependymoma (black star),
white arrowhead pointing
at the remaining
cerebrospinal uid-lled
dural sac
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Fig. 60.3 MRI T2
sequence of the lumbar
spine in sagittal view:
Arrow pointed at the
myxopapillary
ependymoma, arrowhead
pointed at “cap sign”
P. Truckenmueller et al.
60.5 Differential Diagnosis
Differential diagnoses of intraspinal, extramedullary lesions are schwannoma,
spinal meningioma, metastasis, and lipoma. The differential diagnoses of
intramedullary lesions are hemangioblastoma, astrocytoma (Chap. 37), dermoid,
epidermoid, teratomas, and rarely intramedullary metastasis (Chap. 63). In clinical
practice, astrocytoma of the spinal cord is in fact the most frequent and most relevant differential diagnosis since a clear separation of both tumor types is not always
possible via MRI, especially when cysts are missing and the contrast uptake is atypical. Here, the intraoperative appearance and biopsy will only lead to a nal diagnosis (Video 60.8).
60.6 Treatment Options
Most spinal ependymomas are growing slowly and encapsulated, tending to displace the spinal cord rather than to inltrate it. There is usually a dividing layer
between the tumor and the spinal cord tissue allowing for a better separation. Thus,
rst-line treatment of spinal cord ependymomas aims at gross total resection (GTR)
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with preservation of healthy tissue and neurological function. GTR is dened as
resection without visible residual tumor, conrmed in the postoperative MRI, and
can be achieved in the vast majority. It is the main prognostic factor for a progressionfree survival (PFS). In order to maintain neurological function and reduce postoperative complications, intraoperative neurophysiological monitoring (IONM) is
mandatory. However, feasible GTR depends on various factors including location,
growth pattern, and size. As mentioned above, spinal ependymomas sometimes cannot be distinguished well from intramedullary astrocytomas. In this case, the surgical strategy (aiming for GTR in ependymomas versus biopsy/decompression only
for astrocytomas) depends on the results of intraoperative fresh frozen biopsies.
However, the surgeon has to be aware that the reliability of intraoperative biopsy
assessment is only around 70–80%. Thus, in some cases, a staged strategy has to be
applied with biopsy rst and then secondary GTR if ependymoma is conrmed.
If GTR of ependymoma cannot be achieved, postoperative radiation therapy can
be performed. However, there are no guidelines for when radiation therapy should
be performed, and every case should be evaluated individually. Generally, radiation
therapy is recommended for patients with incomplete resection, anaplastic ependymomas, and leptomeningeal spread. For completely resected ependymoma, the controversy about postoperative radiation therapy is even more prevalent.
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60.7 Potential Complications
In pretreated or inltrating ependymomas, surgical removal is challenging, and the
risk of spinal cord irritation due to intraoperative traction and manipulation is high.
Inltration also increases the risk of tumor recurrence due to incomplete resection.
Theoretically, tumors located in the higher cervical spinal cord are associated with
a higher risk of severe neurological impairment including respiratory dysfunction
and quadriplegia, which can cause signicant functional disability. However, in our
experience, the cervical spinal cord is more forgiving than the thoracic spinal cord,
where decits tend to be more complete and more permanent. Further complications include wound healing problems, CSF spread of tumor cells, and CSF leak.
Potential orthopedic complications (spinal deformities) secondary to the surgical
approach must be kept in mind.
60.8 Expected Outcomes
While most patients suffer from sensory decits, increased neurological impairment
including worsening of motor function and spinal ataxia only occurred in about
37% with 9% experiencing a new signicant decit. In the long term, however, 41%
improved and 35% recovered to the preoperative state, leaving only 2% with new
and permanent severe decits. Increased age appeared to be the only independent
predictive factor for permanent neurological decits. In general, the outcome is better in patients with fewer preoperative decits and smaller tumor size, making an
early diagnosis essential.
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