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OPERATIVE NUANCES
Endoscopic Endonasal Resection of Cranio-Cervical
Junction Chordoma and Ventral Chiari
Decompression: A Case Report
Nallammai Muthiah, BS ∗
Michael M. McDowell, MD∗
Georgios Zenonos, MD∗
Nitin Agarwal, MD ∗
Carl H. Snyderman, MD, MBA‡
Robert M. Friedlander, MD,
MA∗
Paul A. Gardner, MD∗
∗Department of Neurological Surgery,
University of Pittsburgh, Pittsburgh,
Pennsylvania, USA; ‡Department of
Otolaryngology, University of Pittsburgh,
Pittsburgh, Pennsylvania, USA
Correspondence:
Paul A. Gardner, MD,
Center for Skull Base Surgery,
Department of Neurological Surgery,
University of Pittsburgh Medical Center,
200 Lothrop St, Suite B400,
Pittsburgh, PA15213, USA.
Email: gardpa@upmc.edu
Received, February 8, 2021.
Accepted, June 28, 2021.
Published Online, August 14, 2021.
C
Congress of Neurological Surgeons
2021. All rights reserved.
For permissions, please e-mail:
journals.permissions@oup.com
BACKGROUND: Chiari I malformations secondary to other causes represent a small subset
of presenting symptomatic cases. Typically, the primary cause of the malformation is
addressed rst and results in resolution of the malformation and symptoms. However, in
some cases, a patient may present with both a primary Chiari I malformation and another
unrelated neurosurgical lesions.
OBJECTIVE: To present a unique case in which resection of a ventral tumor allowed for
spontaneous resolution of a simultaneously noted dorsal Chiari I malformation.
METHODS: Pertinent data, including presenting symptoms, hospital course, surgical
notes, preoperative images, and postoperative images, were collected using the electronic
medical record.
RESULTS: We present a case of a 46-yr-old man with a Chiari I malformation in conjunction
with a ventral cranio-cervical junction chordoma. Endoscopic endonasal resection of
the chordoma and ventral foramen magnum decompression resulted in radiographic
resolution of the Chiari malformation and resolution of his symptoms. Our report repre-
sents a rare case of ventral foramen magnum decompression as a treatment for Chiari I
malformation.
CONCLUSION: It is felt that the chordoma mass eect was not the source of the Chiari I
malformation. Thus, both ventral and dorsal decompressions of the posterior fossa may
be considered for Chiari I decompression in select circumstances.
KEY WORDS: Chiari 1 malformation, Chordoma, Endoscopic endonasal approach, Ventral decompression
Operative Neurosurgery 21:E421–E426, 2021 https://doi.org/10.1093/ons/opab285
Primary Chiari I malformations are
relatively common neurosurgical condi-
tions which can present in childhood
or adulthood.1-4Asymptomatic or mildly
symptomatic patients with Chiari I malforma-
tions are typically managed conservatively.3,5
When significant symptoms are present, patients
usually require surgical decompression of the
foramen magnum with or without duraplasty.5
There have been prior reports of patients with
acquired Chiari I malformations secondary to
space-occupying lesions, which often improve
spontaneously after removal of the primary
lesion.6-9Conversely, cases have also been
reported in which Chiari I malformations did
not spontaneously resolve following resection of
a concomitant space-occupying lesion that was
not directly generating foramen magnum herni-
ation.10 Here, we present the case of a 46-yr-old
male patient with a potentially primary Chiari
malformation who was incidentally found to
have a clival chordoma. Endoscopic endonasal
resection of the clival chordoma allowed for
resolution of his Chiari I malformation via
ventral foramen magnum decompression at the
time of chordoma resection.
METHODS
The electronic medical record was reviewed to
collect patient information regarding pertinent
presenting symptoms, hospital course, surgical proce-
dures, preoperative images, and postoperative images.
This study was approved by our institution’s Institu-
tional Review Board. Informed patient consent was
obtained prior to publication.
RESULTS
A 46-yr-old male presented to our hospital
for a second opinion after experiencing 6 mo of
OPERATIVE NEUROSURGERY VOLUME 21 | NUMBER 5 | NOVEMBER 2021 | E421
MUTHIAH ET AL
FIGURE 1. Preoperative imaging findings. Sagittal T1 with contrast Aand axial T2 of the low clivus Bdemonstrating a
nonenhancing lesion of the lower clivus and upper cervical spine as well as Chiari I malformation. Sagittal T2 of the cervical
spine Cshows associated syrinx. Axial T2 of the cervical spine Ddemonstrates cervical syringomyelia.
insidious-onset dizziness and worsening occipital headache. He
had no history of developmental issues or hydrocephalus. At
another institution, he was found to have a Chiari I malformation
with associated perimedullary edema and a small upper cervical
syrinx. He was also found to have a large ventrally projecting
cranio-cervical junction mass consistent with a clival chordoma.
Subjectively, the patient experienced dizziness, Valsalva-induced
headaches, and intermittent upper extremity paresthesias. He did
not have dysphagia; however, his significant other noted a subtle
change in his speech. On physical exam, he was awake, alert, and
oriented. His cranial nerve function was grossly intact. He was
able to follow commands and had full strength in all 4 extrem-
ities. He had no gait instability or sensory deficits. He had no
evidence of hypertonia or pathological reflexes. Ophthalmologic
examination demonstrated no papilledema.
Review of magnetic resonance imaging (MRI) of the brain
and cervical spine showed a 7-mm tonsillar descent with a
cervical syrinx (Figure 1). Computed tomography angiography
showed bony erosion of the clivus, and bilateral bony erosion
of the occipital condyles. A thin rim of posterior cortex was
noted to still be intact laterally, but complete erosion was noted
centrally. The tumor was not directly compressing the brainstem
or narrowing the foramen magnum (Figure 2). The dura was felt
to be likely uninvaded. A CINE flow study was deferred preop-
eratively because of the need for ventral intervention prior to
consideration of a Chiari decompression procedure regardless of
the results.
After discussion with the patient, an endoscopic endonasal
approach to achieve gross total resection of the clival chordoma
was recommended. By doing so, the hope was to ventrally
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EEA CHORDOMA RESECTION WITH CHIARI DECOMPRESSION
FIGURE 2. Preoperative imaging findings. Sagittal computed tomography (CT) Aand axial CT of the low clivus Bdemon-
strating bony destruction of the lower clivus and bilateral occipital condyles.
decompress the patient’s Chiari malformation without duraplasty
and potentially prevent the need for a subsequent posterior
decompression.
Operative Course
Following endotracheal intubation without issue, the patient
was positioned in the supine position and his head was secured
in a Mayfield™ (Integra LifeSciences, Plainsboro, New Jersey)
skull clamp with the head rotated, extended, and elevated. The
right inferior turbinate was resected and a rhinopharyngeal flap
was elevated before the lower clivus above the tumor was drilled.
Polymer nasal sleeves are inserted as a measure to attempt to
reduce the likelihood of seeding by providing a barrier between
tumor specimen and normal tissues.11,12 The tumor was then
debulked, starting, and the capsule was peeled down from the
lower foramen magnum and then laterally out to identify the
condyle and lateral mass of C1 after bilateral hypoglossal nerves
were stimulated, and the hypoglossal canals localized. A high-
speed drill was then used to drill a wide bony margin, both at
the superior aspect of the C1 arch and the tip of the dens as well
as the inferior and mid-clivus. The medial cortex of the condyles
was drilled as part of the exposure of the hypoglossal canals and
to prevent tumor recurrence, but the joints were carefully not
disrupted. The superior transverse ligament was resected because
of tumor involvement. The tectorial membrane was identified
and appeared to be intact, but tumor was directly adherent and
thus these areas of membrane were resected. The tumor was
peeled laterally from the condyle joint out, where it was eroding
the inferior aspects of the hypoglossal canal greater on the left than
right. Using angled endoscope, the condyle was drilled laterally to
expose the hypoglossal canals. After completion of gross tumor
removal, the medial condyles were decorticated. There was no
evidence of the dural invasion and there were no intraoperative
VIDEO. Operative video depicting the initial surgery as well as
return to the operating room for residual tumor.
cerebrospinal fluid (CSF) leaks. Reconstruction consisted of a
rhinopharyngeal flap, which was transposed superiorly to cover
the ring of C1. Nasal packing was placed (Video).
Postoperative Course
MRI was obtained on postoperative day 1 (Figure 3). This
postoperative MRI showed a small residual tumor of the C1-C2
joint. Chiari I malformation and edema in the upper cervical cord
was still noted. For that reason, a second procedure was performed
4 d later to remove to the residual via the same endoscopic
endonasal approach (Video, start time 4:30). Subsequent imaging
showed gross total resection of the tumor (Figures 4and 5). The
patient’s postoperative course was uneventful. He experienced no
CSF leakage. He was discharged 1 d after stage 2 resection.
Pathological analysis was consistent with chordoma.13 The Ki-
67 proliferation index was 5%. Genetic analyses demonstrated
3.3% of cells expressing a homozygous p16 deletion and 8.3% of
OPERATIVE NEUROSURGERY VOLUME 21 | NUMBER 5 | NOVEMBER 2021 | E423
MUTHIAH ET AL
FIGURE 3. Postoperative brain MRI after first resection attempt demonstrating small, extradural, cranio-cervical residual (arrow) posterior to the left C1 arch at the
depth of the tenorial membrane on T2 axial A, coronal T2 B, and axial T1 with contrast C.
FIGURE 4. Three-month postoperative imaging findings after the second resection attempt. Sagittal T2 of cervical spine A, axial T2 of low clivus B, and axial T2 of
cervical spine Cshowing resection of chordoma, decompression of brainstem, and resolution of syrinx.
cells expressing loss of chromosome 1p, placing the patient in the
intermediate genetic risk category.14-17
Based on this molecular pathology and a gross total resection,
the decision was made to observe the patient before proceeding
with proton beam therapy.
At the patient’s 3-mo follow-up, there was no evidence of
recurrent tumor, nor was there evidence of spinal metastases.
His previous Chiari malformation, cervico-medullary edema, and
small syrinx had resolved, and the foramen magnum was widely
patent (Figure 4). Following resection, the patient’s exertional
headaches and dizziness completely resolved. The patient’s sense
of taste and smell remained intact, his speech improved, and he
experienced no neck pain.
DISCUSSION
We present an unusual case in which tonsillar herniation and
foramen magnum obstruction secondary to Chiari I malfor-
mation was found concomitantly with a clival chordoma.
Endoscopic endonasal approach has previously been used to
directly treat Chiari I malformations via odontoidectomy.18-20
In this case, our patient had both a Chiari I malformation
and a cranio-cervical junction chordoma. Wide clival resection
and decompression of the cranio-cervical junction ventrally
resulted in resolution of the Chiari I malformation radio-
graphically and symptomatically despite no obvious relationship
between the chordoma mass effect and the Chiari I malformation.
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EEA CHORDOMA RESECTION WITH CHIARI DECOMPRESSION
FIGURE 5. Postoperative imaging findings. Sagittal CT of the cervical spine Aand axial CT of the low clivus Bdemon-
strating bony decompression.
There have been several prior cases of tumors with associated or
incidental Chiari I malformations documented in the literature.
For most of these cases, resection of the space-occupying lesion
led to resolution of the associated Chiari.6,9,21-23 However, few
reports also exist in which resection of the symptomatic tumor
did not allow for resolution of the Chiari I.10 Villalonga et al10
presented a unique case of a patient with a nonfunctional pituitary
adenoma and Chiari I malformation associated with posterior
fossa compression. In their case, the authors used an endoscopic
endonasal approach to remove the primary tumor, though the
patient’s Chiari I symptoms persisted. Ultimately, a second
procedure (suboccipital craniectomy with C1 laminectomy and
expansile duraplasty) was required to ameliorate the patient’s
Chiari symptoms.
In our case, resection of the patient’s chordoma allowed
complete resolution of the Chiari I malformation and associated
syrinx. Similar to the abovementioned case, no direct mass effect
relationship appeared to exist between the 2 pathologies, though
the recent onset of occipital headaches in a middle-aged man
does suggest an association between the expanding chordoma
and the Chiari malformation. In our case, the surgical treatment
of chordoma resulted in ventral cranio-cervical junction decom-
pression. An occipital-cervical or atlanto-axial fixation was not
felt to be necessary in this patient’s case. It is our experience that
when only limited drilling of the C1 arch and medial condyles
is performed, fixation is not necessary. In the absence of subse-
quent development of neck symptoms or postural complaints,
we do not typically routinely screen for instability in these cases
beyond what is detectable by MRI images on interval scans for
tumor recurrence. In cases in which one of the condyles is signif-
icantly resected, especially if 75% or greater from an endonasal
approach,24 and in cases in which the entire C1 arch, dens, and
transverse ligament are resected, we favor immediate occipital-
cervical and atlanto-axial fixation, respectively.
Although a suboccipital approach allows for direct manipu-
lation of the tonsils if needed and lysis of adhesions, ventral
decompression in very select circumstances may be therapeutic
by sufficiently expanding the cranio-cervical junction via bony
removal alone. In this case, no direct intervention was required to
correct the primary Chiari I malformation, syrinx, or brainstem
compression. The decompression performed ventrally here is
analogous to the nondural opening procedures, which are
frequently highlighted in pediatric cohorts but are more contro-
versial in efficacy in adult cohorts.25-28 Several mechanisms
have been proposed by which Chiari I malformations in adults
may resolve without direct manipulation, including physiological
changes in intracranial and intraspinal compartment pressures,
atrophy of the cerebellar tonsils with age, and variations in
position of the cerebellar tonsils with age. The resection of the
chordoma may have relieved intracranial pressure, which made
conditions more favorable for the cerebellar tonsils to return
to a more normal configuration. However, chordomas without
profound mass effect have not traditionally been associated
with a predisposition toward high intracranial pressures. Alterna-
tively, the bony decompression of the ventral foramen magnum
allowed for sufficient expansion of the posterior fossa to allow for
separation of the tonsils and brainstem sufficiently to allow for
a more physiological configuration to be restored as is achieved
from a dorsal bony decompression in some cases as mentioned
above.
OPERATIVE NEUROSURGERY VOLUME 21 | NUMBER 5 | NOVEMBER 2021 | E425
MUTHIAH ET AL
This case also further supports the use of the endoscopic
endonasal approach for treatment of ventral brainstem
compression. In unique circumstances such as this, endoscopic
endonasal decompression of the ventral cranio-cervical junction
may be an option for the treatment of very select Chiari I
malformation.
CONCLUSION
This is the first reported case of complete resolution of a
primary Chiari I malformation after ventral chordoma resection
requiring foramen magnum decompression. Ventral brainstem
decompression via an endoscopic endonasal approach is a
safe, effective treatment for such patients and should be
considered when patient anatomy is favorable and when unique
clinical characteristics make ventral approaches for foramen
magnum decompression favorable for the treatment of Chiari I
malformation.
Funding
This study did not receive any funding or financial support.
Disclosures
The authors have no personal, financial, or institutional interest in any of the
drugs, materials, or devices described in this article.
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