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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6029_Библиотеки_им_академика_М_И_Перельмана.pdf
258
Fig. 19.14 Plain laterogram showing C2 significant osteolytic
lesion caused by chordoma
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management. Currently, CT-guided needle biopsy
through the planned surgical incision is preferred to
avoid tumor contamination consequent to the needle
biopsy tract [80, 98]. The risk of track contamination
is considered so high that if the isolated expansion
seems to be easily en bloc resectable (e.g., posterior
arch only), a direct surgical procedure (excisional
biopsy) is preferred [116]. On the other hand, having
tumor diagnosis is still considered crucial before any
complex operative decision is made.
Classification, Grading, and Staging
As was seen in the benign tumors, the sectorial WBB
surgical staging system is also applied to malignant
primary tumor staging and helps in planning of operative options. According to Boriani’s original recommendation, tumors spreading within sectors 4–8 and
5–9 can be radically resected by vertebrectomy (i.e.,
somatectomy); sectors 2–5 and 7–11 by sagittal vertebral resection; and sectors 10–3 by posterior arch
removal. Complete radical resection, however, can be
achieved only within the limits described previously.
The Enneking staging system has also been adopted
for the purpose of staging of primary malignant spine
tumors [21, 116]:
Fig. 19.15 Plain lateral film showing only a mild osteolysis of
cranial C3 edge caused by chordoma (same patient in Figs. 19.16
and 19.17)
tumor sites (also, “whole” body CT or spine MRI).
CTA or MRI can often demonstrate tumor relationship
to the VA, show neovascularization and can help plan
for potential preoperative tumor embolization or VA
trapping. Percutaneous needle or incisional biopsy to
distinguish tumor type and to histologically grade the
tumor is usually the first step in operative
S I Low grade malignant primary bone tumors (e.g.,
chordoma, chondrosarcoma)
I a Intraosseous, intravertebral
I b Tumor invades perivertebral compartments having
only pseudocapsule
S II High grade malignant tumors (e.g., Ewing
sarcoma, osteogenic sarcoma)
II a Intraosseous
II b Extraosseous spreading
S III High grade malignant tumors having secondary
focuses (metastases) at presentation
III a Intra-compartmental
III b Extra-compartmental invasion
Treatment
The treatment is often complex and the decision-making
process needs to be a result of multidisciplinary oncologic team discussion. The patient and their family
19.1 Extradural UCS Tumors
259
must be involved and their compliance ensured, especially if radical surgery with a high frequency of potential complications is the best option. It has been
frequently reported that wide tumor resection can dramatically decrease the rate of local recurrence even to
zero [35, 49, 69, 75, 104, 119]. Radical surgery is the
ideal modality in majority of such tumors;however, the
often late diagnosis and UCS location make it impossible in the vast majority of cases. Both, the anatomy
of the UCS and associated vital structures, as well as
the patient’s general medical status dictate the extent
of the surgical procedure. The difficulty of radical
resection procedures, as well as the major morbidity
and considerable mortality, necessitates the question
of whether they are justified [49, 50]. Neoadjuvant
and/or adjuvant radiation and chemotherapy are often
added, however, long-term survival is more an exception than the rule. For the definition of cure in primary
malignant bone tumors, the standard should be considered as disease-free survival of more than 10 years
[116]. The most common primary malignant tumors
diagnosed in the UCS are chordoma, chondrosarcoma,
Ewing sarcoma, and osteosarcoma. Malignant fibrous
histiocytoma, synovial sarcoma, and rhabdomyosarcoma are rarities in this region. Also, occasionally
found in this region are solitary myeloma and nonHodgkin’s lymphoma.
cord represent a late manifestation, usually indicating
extra-compartmental intraspinal tumor growth.
Plain films can demonstrate an osteolytic lesion
with retropharyngeal space enlargement, or a deformity caused by vertebral destruction (Fig. 19.14), or
can be nearly normal if the majority of tumor is located
extra-compartmentally (Fig. 19.15). CT delineates the
intravertebral osteolytic lesion with frequent extracompartmental tumor expansion (Fig. 19.16). The soft
tissue relationships can be easily documented by MRI
(Fig. 19.17). The tumor commonly extends anterolaterally from the vertebral body, but the epidural space
can also be affected. The VA is often encapsulated by
tumor tissue necessitating vertebral CTA, although the
tumor itself is often not very vascularized. Correct
WBB and Enneking staging done by oncologic team
can guide the treatment strategy and estimate the feasibility of radical surgery.
Treatment Strategy
Currently, it is understood, and in other parts of spine
proven, that only radical surgical removal of the tumor
can lead to long-term cure [17, 35, 103, 124].
Chemotherapy is ineffective in chordoma and the
benefit of adjuvant radiotherapy is still the subject of
19.1.4.3 Chordoma
Chordoma is a slow-growing malignant primary bone
tumor derived from primitive notochord remnants and
most commonly involves the clivus and the sacrum
[15, 17, 41]. Less frequently, they occur in the cervical
spine but if affecting the USC the second cervical vertebra is predominantly involved [8, 64, 72]. They are
known to be locally invasive, recurrent, and resistant to
chemotherapy. The majority of patients are men older
than 50 years, although older females can be affected
also. Their long term mortality is very high.
Diagnosis
Most of the patients present late in the disease course
suffering from non-specific neck pain, swallowing difficulties and occipital headache, and have been treated
conservatively without radiographs. Neurological signs
(quadriparesis) due to direct compression of spinal
Fig. 19.16 Axial CT scan of C3 chordoma expanding retropha-
ryngeally with simultaneous invasion of extradural
compartment
260
Fig. 19.17 MRI in sagittal T1 sequence depicting anterior and
intraspinal chordoma extend (same patient as on Figs. 19.15 and
19.16)
some debate [4, 115, 117]. Positive results showing
better long-term local tumor control have been
described only for high energy particle (proton) beam
or combined proton–photon irradiation performed
after tumor resection [22, 63, 86, 92]. Nevertheless,
the extent of tumor removal and the amount of remnant invaded tissue play a substantial role in the effectiveness of any adjuvant radiotherapy.
Surgical radical resection in the case of UCS chordoma is, in fact, feasible only in the very early stage of
tumor growth; however, in cases where both anterior
and posterior vertebral elements are involved (nearly
always anatomically and always in oncologic terms),
en-bloc resection (total spondylectomy) is the treatment of choice. This has been extensively described in
other parts of the spinal column [2, 36, 52, 82, 124] but
total spondylectomy of C2 is technically challenging
given its anatomical relationship to the vertebral arteries, particularly when their preservation is desired
[103, 108, 114] . The goal of such radical procedures is
to not only remove the tumor, but also any potentially
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involved bone, and thus decrease the rate of recurrence
[65]. However, the benefits of such radical procedures
must outweigh its risks. An extensive radical resection
should be done only when reasonable survival (greater
than 2 years) is expected [21, 103, 114].
Our Preference
Given our experience with early recurrence of chordoma after two-staged radical resection (Fig. 19.18),
we feel that only maximally radical single-stage procedure prolongs the disease-free interval.
Wide-margin resection is indicated in cases where
there is a concern for potential dissemination of tumor
cells in the surgical wound. In cases of malignant bone
tumors, a total spondylectomy appears to be a better
oncologic procedure with improved recurrence rates [2,
36, 108]. Upper cervical spondylectomies are compli-
cated by the complex anatomy and the presence of vertebral arteries. Authors that have reported upper cervical
spondylectomies, were usually forced to sacrifice the
involved VA [8, 103] in order to achieve wide-margin
resection of tumor and potentially involved soft tissues.
We have described a case of total endolesional
spondylectomy in a 64-year-old man whose chordoma
was staged as Enneking I b and WBB A-D,F/ 3–8
[114]. CT showed the intraosseous extent of the tumor
(Fig. 19.19); however, MRI documented extradural
spreading and left VA involvement (Fig. 19.20). The
VA balloon occlusion test was performed preoperatively and was positive with neurologic deficit lasting
for 48 hours (Fig. 19.21). The patient was fully
informed and decided to proceed with a recommended
C2 spondylectomy through a combined transoral-posterior single-stage surgery. The procedure was performed beginning with transoral anterior segment
removal and reconstruction (Fig. 19.22) followed by
posterior C2 segment removal, sparing the left VA with
concurrent middle column reconstruction and occipitocervical fusion (Fig. 19.23). He was irradiated conventionally afterwards and proton irradiation was not
applied due to economic reasons.
The status of this particular patient was good and on
1-year follow-up was without signs of recurrence on
repeated MRIs (Fig. 19.24) and CTs; however, later in
his course, a recurrence appeared on the left side. To
date, he has had two reoperations with acceptable
results and still remains ambulatory.
19.1 Extradural UCS Tumors
261
Fig. 19.18 The same patient (Figs. 19.15–19.17) after a two-
stage total endolesional spondylectomy with sparing of both
VAs. (a) Three months after the surgery lateral plain radiogram
without marked signs of recurrence. (b) Nine months later, the
Although the primary goal of the procedure is radical resection of chordoma, reconstruction of the created defect poses its own challenges. Previous case
reports demonstrate that cervical constructs following
spondylectomies are prone to failure [103]. A mesh
cage secured to C1 arch, or its remainder anteriorly
probably does not provide an adequate biomechanical
support of the construct, especially if recurrence can
be expected. Further, preservation of the atlas arch
anteriorly would make a safe removal of the odontoid
tip difficult. We believe that direct fixation to the clivus
may represent a more robust alternative to previously
described techniques. The use of a navigation system
allows for safe placement of the cage and screws and
also helps in determining the appropriate screw length.
The angle of the clivus and the need for a perpendicular screw entry requires an angle that cannot be
achieved through a transoral approach. This problem
was solved using a surgically created, submandibular
same patient returning intubated with quadriparetic symptoms
deemed inappropriate for any surgical intervention. MRI showing recurrence directly compressing spinal cord
channel through the floor of the mouth. Reconstruction
of the middle column using cages placed between the
articular surfaces increases the chance of bony fusion
and also potentially offloads the strain on posterior
occipitocervical fixation particularly in the case of
potential tumor recurrence. To further increase the
strength of the construct, all lateral mass screws were
placed bicortically. Bony fusion was reinforced through
autograft bone placed between occiput and each
spinous process.
Although recent literature demonstrates that a widemargin, en-bloc resection of chordomas involving the
spine provides the patient with the best chance of disease-free survival [8, 35, 52, 103, 124], ours and other
previously reported cases [15, 17] demonstrate that
this may not always be possible in the cervical spine.
We believe that, as the experience with resections for
this rare condition widens, reconstructive techniques
will be required to match those improvements.
262
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Fig. 19.19 Preoperative CT of the cervical spine demonstrates an osteolytic process – chordoma of the second cervical vertebra
with involvement of both anterior and posterior elements. (a, b) Axial plane. (c) Sagittal plane image
19.1 Extradural UCS Tumors
263
Fig. 19.20 Preoperative MRI of the cervical spine confirms a
chordoma (from Fig. 19.19) predominantly affecting the vertebral body of axis and left lateral transverse process. There is
epidural and extraverterbal disease displacing the left vertebral
artery laterally. (a, b) Transverse plane. (c) Sagittal plane
264
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Fig. 19.21 The left vertebral artery was draped over the lateral
aspect of the tumor and a diagnostic angiogram demonstrated
vessel patency. However, the patient did not tolerate a balloon
occlusion test. (a) Artist’s illustration of VA tumor relationship.
(b) Vertebral angiogram of left VA. (c) Angiogram obtained during balloon test occlusion (x2)
19.1 Extradural UCS Tumors
265
Fig. 19.22 Anterior reconstruction constituted of a Harms mesh
cage filled with autograft and hydroxyapatite paste. The cage
was screwed into the clivus cranially and C3 vertebral body caudally. (a) Artist’s illustration of cage position in antero-posterior
view. (b) CT reconstruction in midsagittal plane showing exact
clival screw purchase (note the angle). (c) The right-angle to
clivus achieved by submandibular introduction of the image
navigated drill
266
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Fig. 19.23 The final construct consisted of the anterior cage,
two mesh cages placed between the lateral masses of C1 and C3
on the right and C4 on the left, and was completed by an occipitocervical fixation and fusion extending down to C6. C1 lateral
mass screws passed through the two mesh cages supporting the
lateral masses. (a) Artist’s illustration of the final construct – left
side view. (b) Lateral slightly oblique plain film of final construct. (c) Transoral plain film of final construct
19.1 Extradural UCS Tumors
267
Fig. 19.24 MRI performed a year after the surgery showing patent VAs and no tumor recurrence. (a) Sagittal T2 sequence. (b)
Coronal image
19.1.4.4 Chondrosarcoma
secondary malignant change of Paget’s disease, or osteochondroma to chondrosarcoma is also possible [105].
Chondrosarcoma of the spine is rare (in particular, in the
cervical region) with only case reports of UCS involvement [13, 42, 71]. Reported prevalence of chondrosar-
Diagnosis
coma in the spine is more than 6% [27]. Törmä, in his
paper describing 250 histologically verified malignant
spine tumors, found 11 cases of chondrosarcoma [126].
It is composed of cells having tendency to differentiate to chondrocytes, therefore foci of osteolysis can be
mixed with nests of cartilage-like tissue and ossifica-
Clinically, symptoms are nonspecific until the neural structures are compromised. In posterior locations, suboccipital
neuralgia can dominate. Radiologically, the mass usually
appears to be extending out of vertebra and is irregular,
lobulated with granular ossifications visible on CT or MRI.
tions. Chondrosarcoma is a slow-growing tumor often
located in posterior vertebral elements, spreading outside
as extraosseous mass; however, circumferential spread is
Treatment Strategy
also possible. The histological grading is very important,
as the low grade tumors (Gr I) are surgically controllable
for long periods, whereas high grade tumors (Gr II+III)
recur early [121]. Metastases are not frequent and if they
occur, it is usually late with predilection for the lung. The
Recurrences after incomplete resections are frequent
and the patients die after many surgeries and multiple
revisions (mean recurrence survival of 20% at 5 years)
[27]. As adjuvant therapy is considered to be not very