Can Posterior Midline Approach Provide Adequate Exposure for All CraniovertebralJunction Tumors?

orkun 1, Kas, 2023

Genel

INTRODUCTION: The surgical treatment of cranio-
vertebral junction (CVJ) lesions remains a difficult process

requiring advanced experience. The aim of this study was
to present our experience and the clinical results of a
posterior and posterolateral approach used for CVJ lesions
in our clinic, and to discuss these in light of current
literature.

METHODS: Clinical, radiologic, and surgical aspects of

30 patients with CVJ tumors were retrospectively evalu-
ated. Age, sex, symptoms, tumor localizations, pre- and

postoperative neurologic examinations, performed surgical

techniques, postoperative complications, and tumor pa-
thologies were analyzed. The modified McCormick clas-
sification was used in the evaluation of the neurologic

examination.

RESULTS: There were 30 patients (12 men, 18 women;
mean age: 41.8 years). Hemilaminectomy was performed in
14 cases, and total laminectomy or laminoplasty in 16
cases; additional suboccipital craniectomy was performed

in 6. Postoperative mortality was observed in 1 (3.3%) pa-
tient in the early postoperative period following tetrapa-
resis, motor deficit in 2 (6.6%), cerebrospinal fluid leakage

in 2 (6.6%), and wound site infection in 1 (3.3%). A tumor
rest was detected in 2 patients (6.6%).

CONCLUSIONS: A posterior or a posterolateral approach
is a safe surgical technique that can provide total tumor
resection for CVJ region lesions, including posterior,
posterolateral, lateral, and anterolaterally located tumors.
Isolated anterior and anterolateral tumors with small

lateral extension may require a far lateral or extreme
lateral approach combined with other cranial base
techniques.

INTRODUCTION

Craniovertebral junction (CVJ) lesions are relatively un-
common and constitute 1.1%e3.8% of all spinal cord and

brain tumors.1,2
Of CVJ lesion types, the most commonly seen intradural

extramedullary neoplastic lesions are meningiomas, schwanno-
mas, neurofibromas, paragangliomas, and dermoid tumors, and

intramedullary lesions are ependymomas and hemangio-
blastomas. Each lesion has a different growth pattern with respect

to surrounding tissue invasion and involvement of neurovascular

structures. In the surgical treatment of each one, a specific sur-
gical approach and technique is required.3,4 These lesions usually

include very important neural and vascular structures, such as the
vertebrobasilar system, the lower cranial nerves (IX, X, XI, XII),

and the medulla oblongata.5-7 Detailed preoperative neuro-
radiologic evaluation with computed tomography (CT), magnetic

resonance imaging (MRI), or magnetic resonance angiography is
necessary to determine the appropriate surgical approach. The
surgical treatment of CVJ lesions remains a difficult process

requiring advanced experience. In addition, because of the path-
ologic range, different clinical presentations, and the difficulties

encountered in surgical excisions, this region has long been an
area of interest to neurosurgeons.
The aim of this study was to present our experience and the
clinical results of a posterior and posterolateral approach used for

Key words

Craniovertebral junction tumors
Instability
Midline approach
Abbreviations and Acronyms
CT: Computed tomography
CVJ: Craniovertebral junction
MRI: Magnetic resonance imaging
Department of Neurosurgery, Ümraniye Training and Research Hospital, _
Istanbul, Turkey

To whom correspondence should be addressed: Furkan Avcı, M.D.
[E-mail: favci88@gmail.com]
Citation: World Neurosurg. (2022) 161:e482-e487.
https://doi.org/10.1016/j.wneu.2022.02.044
Journal homepage: www.journals.elsevier.com/world-neurosurgery
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Original Article

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CVJ lesions in our clinic, and to discuss these in light of current
literature.
METHODS
A retrospective examination was made of cases with intradural
tumors with CVJ localization who were operated on in our clinic
between April 2010 and September 2020.

The study included all intradural tumor cases showing locali-
zation at the C1-C2 level or extension to this region. All the sur-
gical operations were performed by the same primary surgeon and

team.
Study Inclusion Criteria

Determination of tumoral tissue in the region of the intradural
component inferior to the C2 corpus, including the foramen
magnum.
Tumoral tissue within the spinal cord or adjacent to it, with
intradural localization or intradural þ extradural localization.
No history of surgery in the craniocervical region.
Tumoral tissue reported as a result of pathology sampling.
Study Exclusion Criteria
Pathologic lesion other than in the defined CVJ region.
The presence of a lesion originating from a pathology other
than a tumor or cystic structure, confirmed by pathology
sampling.
A history of craniocervical surgery.
Completely extradural localization of the lesion.
No pathologic sampling.
Congenital CVJ anomalies.
Data Collection
A total of 30 cases with intradural tumors who met the study

criteria were included in the study. Informed consent was ob-
tained from all patients in the study.

Data related to demographic characteristics, symptoms, and

perioperative complications were obtained from the medical re-
cords. Clinical evaluation was generally based on preoperative and

postoperative neurologic function evaluations. The modified
McCormick classification was used in the evaluation of the
neurologic examination.
Preoperative CT, CT angiography, and MRI were taken of all
patients for the evaluation of tumor characteristics, localization,
and degree of invasion.
In the postoperative period, contrast MR images were taken of
all the patients within the first 48 hours, then at 3, 6, and 12
months, and evaluated.
The diagnosis of tumor-cyst was confirmed in all cases with
pathologic examination.
A numbering system was used in the study to visualize the
localization and define the relationship between surgical approach
and postoperative complications (Figure 1).

Surgical Technique

After intubation, the patient was positioned prone on the oper-
ating table. A midline skin incision was made appropriate to the

tumor localization. According to the conditions of each case,

unilateral or bilateral paravertebral muscles were stripped peri-
osteally. In a unilateral approach, the contralateral muscles, liga-
ments, lamina, and facets were spared. Lamina at the level desired

by the surgeon were removed using a Kerrison rongeur and a
high-speed drill or ultrasonic bone cutter. To expose the dura, the
ligamentum flavum was excised using a Kerrison rongeur. The

status of the vertebral artery was continuously verified intra-
operatively with Doppler. The lesion localization was then iden-
tified with ultrasonography captured perioperatively. Evaluation

was made as to whether sufficient lamina excision had been made.
Dura intramedullary tumors were opened with a median linear
incision, and extramedullary tumors with a paramedian linear
incision, suspended bilaterally with 2-0 silk sutures.
The posterior midline was generally used for durotomy and
myelotomy in intramedullary lesions, and in some cases such as

hemangioblastoma, myelotomy was made from paramedian dur-
otomy and dorsal root entry zone. After reaching the tumor or

cyst, it was excised piece by piece. In appropriate cases, debulking
was performed using an ultrasonic aspirator.
In intradural extramedullary lesions, paramedian durotomy was
applied. The arachnoid was cut to expose the tumor. Dissection

was then carefully performed without damaging the vertebral ar-
tery and neural structures. By verifying the localization and

extension of the vertebral artery with Doppler at this stage, the
connection between the vertebral artery and tumor was dissected
and covered with a cotton pad. In cases of extramedullary tumor,
positioning on the operating table was made from time to time,
appropriate to the extension of the tumor. After cutting the dural
connection of the tumor, it was removed piecemeal.
Following tumor resection, primary closure of the dura was
made with 5.0, 4 mm, 3/8 Vicryl (Ethicon, Bridgewater, NJ), and
fibrin adhesive (Tisseel, Baxter, Dererfield, IL; Beriplast, CSL
Figure 1. Schematization of localization on axial T2-weighted MRI sections
of craniovertebral junction tumors.

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ORIGINAL ARTICLE
EYÜP VAROL ET AL. MIDLINE APPROACH FOR CVJ TUMOR

Behring, King of Prussia, PA) was used for strengthening. In cases

performed with laminoplasty, lamina grafts removed with an ul-
trasonic bone cutter were placed in anatomic positions with 2-

0 silk suspension sutures. Paying the utmost attention to control
and hemostasis, the layers were closed anatomically without the
use of a drain. Neuromonitorization was performed throughout
the operation in all cases.
RESULTS
Evaluation was made of 30 patients, 12 men and 18 women, with a
mean age of 41.8 years (range: 23e70 years).
In 8 cases the main bulk of the tumors were found to be in zone
5 (26.6%), in 7 cases in zone 3 (23.3%), in 5 cases in zone 4
(16.5%), in 3 cases in zone 1 (10%), in 3 cases in zone 6 (10%), in 2
cases in zone 7 (6.6%), and in 2 cases the main bulk was found to
be in zone 8 (6.6%). There was no main tumor bulk in zone 2 in
this series (Figure 2).
The majority of complaints on presentation at the clinic were

associated with neural pressure, with patients most often pre-
senting with neck pain (77%), followed by numbness in the arms

(53%), weakness in extremities (23%), and spasms in the legs
(20%).
In the preoperative evaluation, motor deficit was determined in

the upper and/or lower extremities in 7 (23%) patients. Preoper-
ative neurologic deficits were found to be in zone 5 tumors in 3

cases. There was only 1 case in zone 1, zone 3, zone 6, and zone 7
cases.
The postoperative pathology results of the cases are shown in
Table 1, and the relationships between tumor pathology and
localization are shown in Table 2. According to these results,
the most frequent pathologies were ependymoma (23%),
schwannoma (20%), meningioma (17%), and neurofibroma (13%).

Hemilaminectomy was performed in 14 cases, and total lam-
inectomy or laminoplasty in 16 cases (Table 3). In addition to the

details shown in the table, there was seen to be cranial extension
of the tumor tissue from the foramen magnum in 6 cases, and
there was a need for a suboccipital craniectomy procedure to be
performed in addition to the defined laminectomy or
laminoplasty.
According to the numbered schematization method applied to
the cases, 9 tumors showed extension to region 1; 9 to region 2; 9
to region 3; 8 to region 4; 11 to region 5; 12 to region 6; 8 to region
7; 7 to region 8; and 8 to region 9.
In the 7 cases with motor deficit, the preoperative modified

McCormick scores were measured as 2 in 3 patients, 3 in 3 pa-
tients, and 4 in 1 patient. Full recovery of motor deficit was seen

postoperatively in 1 patient with a score of 2, in 1 patient with a
score of 3, and in 1 patient with a score of 4. In 2 cases with a
preoperative McCormick score of 1, motor deficit was observed
postoperatively, in 1 patient evaluated as score 4, and in 1 as
score 3.

Figure 2. Illustration of the posterior approaches to the
craniovertebral junction tumors. Posterior approach via
laminectomy for a tumor with main bulk located in zone
8 (A), zone 9 (B), zone 6 (C), and zone 3 (D). Posterior

approach via occipital condyle drilling and vertebral
artery transposition, for a tumor with main bulk located
in zone 2 (E).

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EYÜP VAROL ET AL. MIDLINE APPROACH FOR CVJ TUMOR

Intramedullary Tumors
Of the operated patients, exitus was observed in 1 (7.6%) patient
in the intensive care unit in the early postoperative period
following tetraparesis, cerebrospinal fluid leakage was seen in 2

(15%), and wound site infection in 1 (7.6%). On the early post-
operative MRI of 1 (7.6%) patient, residue was observed, so the

patient was operated on again and the tumor was totally removed.
In the patient with tetraparesis, localization included region 5
according to the defined schema, and the patient with residual
tumor included regions 2, 3, and 6.
Extramedullary Tumors
No postoperative complications were seen in any patient. Residual
tumor was observed in 1 case, and the localization of the tumor
was regions 1, 2, and 4.
Tumors With Extension to the Extradural Area
Postoperative complication of cerebrospinal fluid leakage was
observed in 1 patient, who was operated on again. No residual
tumor tissue was observed in any of the patients.
DISCUSSION
The results of this study revealed the effectiveness of the posterior

midline approach and C1 hemilaminectomy in almost all intra-
dural tumors, with the exception of tumors totally located anterior

to the spinal cord without lateral extension. Our experience has
demonstrated that tumors located laterally and anterolaterally to
the spinal cord can be resected successfully. Tumors located
anterior to the spinal cord with extension to the lateral dura can
also be safely and completely resected. The only limitation of this
approach is for anterior tumors without lateral extension.
Intramedullary Tumors of the Craniovertebral Junction
While gliomas constitute 80% of CVJ intramedullary tumors,
60%e70% are astrocytomas, which are seen more in children, and
30%e40% are ependymomas, which are seen more in adults.8
Less frequently, hemangioblastoma and metastases can be
observed, and very occasionally, lipoma, mesenchymal, germ

cell, dermoid, epidermoid, and hematopoietic cell tumors can
be seen.8,9 In the current intramedullary cases, ependymomas
were observed at the rate of 53%, hemangioblastoma at 23%,
and astrocytoma and rare pathologies at 7%.
Although median suboccipital, lateral suboccipital, and purely

cervical approaches have been described for intramedullary tu-
mors, a median approach was used in the current study cases. Of

13 patients, suboccipital craniectomy was added to laminectomy in
3 (23%) cases. In all the intramedullary tumors, median durotomy
and median myelotomy were performed, and in patients with
hemangioblastoma, paramedian durotomy and myelotomy from
the dorsal root entry zone were performed.
Extramedullary Tumors of the Craniovertebral Junction

In 17 (56.6%) of the current study patients, extramedullary local-
ization was observed, and extradural extension was observed in 11

(37%). Of these 11 patients, meningioma was present in 4 (36.6%),

schwannoma in 2 (18.8%), neurofibroma in 2 (18.8%), and gan-
glioneuroma, arachnoid cyst, and endodermal cyst in 1 (9%) pa-
tient each. A median skin incision was used as the approach in

these patients, and a suboccipital craniectomy was added to the
laminectomy in 4 (36.6%) patients.
In addition to extramedullary tumor localization, there was also
seen to be extradural extension in 6 patients, 4 of which were
schwannomas and 2 neurofibromas. In all these cases, a median
cut was made followed by hemilaminectomy, and no additional
suboccipital craniectomy was performed in any of these cases.
Many approaches have been described and applied in surgery,
including posterior midline,10-23 posterolateral,20,24-28 lateral,29,30
far lateral,16,23,27 extended far lateral,16 extreme lateral,31
transcondylar,2,21,22,31-35 partial transcondylar,36 retrocondylar,36
dorsal lateral,17,37 anterolateral,20 and transoral.22 In the
literature related to the anterior approach to this region, Kanavel
first described microsurgery with a transoral transpharyngeal
approach in 1919, and in recent years these techniques have
been further developed.38 Kassam et al. showed that these
approaches provided a sufficient opening from the clivus as far
as C2 or C3, irrespective of the depth of the lesion, and reported

Table 1. Histopathology Results of 30 Operated Cases
Tumor Type Number of Cases
Ependymoma 7 (23%)
Schwannoma 6 (20%)
Neurofibroma 4 (13%)
Meningioma 5 (17%)
Hemangioblastoma 3 (10%)
Endodermal cyst 2 (7%)
Astrocytoma 1 (3%)
Arachnoid cyst 1 (3%)
Ganglioneuroma 1 (3%)
Total 30 (100%)

Table 2. Tumor Localization According to Tumor Histopathology
Tumor Type Intramedullary

Intradural
Extramedullary

Extradural
Extension
Ependymoma 7 – –
Schwannoma – 2 4
Neurofibroma – 2 2
Meningioma 1 4 –
Hemangioblastoma 3 – –
Endodermal cyst 1 1 –
Astrocytoma 1 – –
Arachnoid cyst – 1 –
Ganglioneuroma – 1 –
Total 13 (43%) 11 (37%) 6 (20%)

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ORIGINAL ARTICLE
EYÜP VAROL ET AL. MIDLINE APPROACH FOR CVJ TUMOR

that alveopalatal insufficiency in cases could require posterior
occipital fixation, and if there is a risk of cerebrospinal fluid
fistula and infection risk, an endoscopic endonasal approach
applied subsequently reduced the risk of velopharyngeal
failure.39,40 The anterior approach has not been widely used
because of both the difficulty and complications.
Since the introduction of the posterolateral and anterolateral
approach concepts, there have been developments with various
modifications made with increasing bone resections.20,41,42
Variants of the far lateral approach, such as transcondylar,
transtubercular, and transfacetal, require a greater lateral area for

better exposure, and have been developed to meet these condi-
tions and have a sufficient lateral visualization area.2,29,43

In a series of 69 patients, Sekhar et al. described several variants
of the far lateral approach as retrocondylar, partial transcondylar,

complete transcondylar, far lateral transjugular, and
transtubercular.44
The results of the current study show that most lesions can be

removed using posterior approaches. Tumors located in the pos-
terior or posterolateral of the CVJ can generally be safely resected

with a posterior midline suboccipital approach together with C1
laminectomy. However, when tumors are located anteriorly or
anterolaterally, resection becomes more difficult with traditional

approaches. Nevertheless, the type of approach relies on the na-
ture, location, and size of the tumor. The laterality of the tumor is

the most important determinant. Whereas anterolateral tumors
with major lateral tumor bulk and small anterior midline tail or
extension can be resected successfully via a posterior approach,
those tumors with major anterior midline bulk and small lateral
tail may require other techniques to sufficiently enlarge the
working area.
CONCLUSIONS

As seen from the results of this study, a posterior or a postero-
lateral approach is a safe surgical technique that can provide total

tumor resection for CVJ region lesions, without touching the

vertebral artery, drilling the occipital condyles, or causing cra-
niovertebral instability. Only isolated anterior and anterolateral

tumors with small lateral extension may require bony resection via
far lateral or extreme lateral approach combined with other cranial
base techniques.
CRediT AUTHORSHIP CONTRIBUTION STATEMENT
Eyüp Varol: Investigation, Data curation, Resources, Writing e
original draft. Mustafa Umut Etli: Data curation, Visualization,
Formal analysis. Furkan Avcı: Investigation, Data curation. Ali

Fatih Ramazanoglu: Writing e original draft, Resources, Inves-
tigation. Serdar Onur Aydın: Formal analysis, Data curation.

Cumhur Kaan Yaltırık: Methodology, Resources, Writing e re-
view & editing. Sait Naderi: Conceptualization, Methodology,

Resources, Writing e review & editing, Supervision, Project
administration.

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Conflict of interest statement: The authors declare that the
article content was composed in the absence of any
commercial or financial relationships that could be construed
as a potential conflict of interest.
Received 5 December 2021; accepted 11 February 2022
Citation: World Neurosurg. (2022) 161:e482-e487.
https://doi.org/10.1016/j.wneu.2022.02.044

Journal homepage: www.journals.elsevier.com/world-
neurosurgery