Vascular Compression of the Medulla
Oblongata by the Vertebral Artery:
Report of Two Cases
Kazuhiro Hongo, M.D., Hiroshi Nakagawa, M.D.,
Nobuhito Morota, M.D., Masanori Isobe, M.D.
Department of N eu ro lo g ical Surgery, A ic h i M e d ic a l U n iv e rs ity , N ag akute, A ic h i, Japan

OBJECTIVE AND IMPORTANCE: Compression of the medulla oblongata by
a tortuous vertebral artery is rare. W e report two patients with this lesion
who were treated with vascular decompression of the vertebral artery.
CLINICAL PRESENTATION: A 36-year-old man developed right hemiparesis
with lower cranial nerve deficits, and a 47-year-old man developed left
lower cranial nerve deficits and left cerebellar dysfunction. In both
patients, magnetic resonance imaging revealed a tortuous vertebral ar­
tery compressing the medulla oblongata.
INTERVENTION: In both patients, the compressed medulla oblongata was
treated by detaching the vertebral artery from the medulla oblongata,
shifting it, and anchoring it to the nearby dura mater. Postoperatively,
both patients are asymptomatic and have returned to their previous jobs.
CONCLUSION: Although compression of the medulla oblongata by a tortu­
ous vertebral artery is rare, it can cause brainstem dysfunction. Magnetic
resonance imaging clearly revealed the vascular compression in these
patients. Surgical treatment was effective. The symptoms related to a
tortuous vertebral artery and some techniques for surgical treatment are
discussed. Awareness of this rare lesion is necessary to ensure appropriate
treatment. (N eu ro surge ry 4 5 :9 0 7 - 9 1 0 , 1999)
Key words: M edu lla oblongata, V a s c u la r co m p ressio n , V erteb ral artery

T h e concept of neurovascular com­
pression as cranial nerve dysfunction resulting from the vascular com­
pression of cranial nerves is w idely
accepted. However, there are very few
rtP()fts of brainstem dysfunction caused
} Oscular compression. Kim et al. (5)
VUre the first to report such a patient,
clnd there have been several subsequent
reP°rts (2, 4, 6, 8-10). The authors re­
ported a similar case previously in
w ich the elongated vertebral artery
Caused a progressive pyram idal tract
and the artery was eventually sec*0ned to relieve the neurological signs
^ )•In this report, we present two patients
u 0 were treated successfully with mi­

crovascular decompression achieved by
shifting the tortuous vertebral artery.
Because a tortuous, thick vertebral artery
usually causes the compression, careful
and adequate decompression is needed to
treat this type of lesion operatively. The
routine placement of a prosthesis to
achieve microvascular decompression in
the treatment of hemifacial spasm or
trigeminal neuralgia may not be adequate
to achieve a definitive surgical result and
to avoid recurrence in these patients.
W e report two such patients, describe
the symptoms related to the tortuous
vertebral artery, and discuss some of
the su rg ica l tech n iq u es used for
treatment.

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CASE REPORTS
Patient 1
A 36-year-old man, who was a pedi­
atrician, was admitted to our institute
with a 9-month history of right hemipa­
resis, hemisensory disturbance, and slight
difficulty swallowing. These symptoms
gradually worsened before admission.
Exam ination
A t admission, the neurological exam­
ination disclosed an onionskin-like hypalgesia, a diminished gag reflex on the
right side, and slight atrophy of the
right sternocleidomastoid and supraspinatus muscles. M ild right hemiparesis
was also noted. Preoperatively, M R I re­
vealed significant compression of the
right anterolateral side of the medulla
oblongata, indicating a tortuous right
vertebral artery that was causing severe
indentation at the medulla (Fig. IA ). The
right vertebral angiogram (Fig. 2) re­
vealed a tortuous, elongated right ver­
tebral artery and deviation of the verte­
bral union to the right. His symptoms
and the M R I findings suggested that the
vertebral artery was the cause of his
symptoms. Surgery was performed af­
ter obtaining informed consent from the
patient.
O peration
The patient was placed in the left lat­
eral decubitus position under general
anesthesia. A right suboccipital craniot­
omy was performed. The dura mater
was opened, and the inferolateral por­
tion of the posterior fossa was exposed.
There was marked compression of the
anterolateral portion of the medulla ob­
longata by a m edially bent and tortuous
vertebral artery at the level of the hypo­
glossal nerve, anterior to the dentate lig­
ament. The vertebral artery was care­
fully separated from the medulla
oblongata and from the small vessels. A
7- X 20-mm piece of Teflon felt was
inserted beneath the vertebral artery
and used to elevate the artery; 5-0 nylon
sutures were used to anchor it to the
dura mater near the foramen magnum.

907

908

Hongo et al

F IG U R E 1. T2w eighted M R I

artery. Surgery was performed after
obtaining informed consent from the
patient.

scans of Patient 1.
A , preoperative

O p eration

M R I scan revealing

The patient was placed in the right
decubitus position under general anes­
thesia, and a left suboccipital craniot­
omy down to the foramen magnum was
performed. The lateral edge of the fora­
men magnum was widely drilled out
near the occipital condyle, and the dura
mater was opened. The vertebral artery
was exposed by retracting the cerebel­
lum and evacuating the cerebrospinal
fluid. The vertebral artery appeared to
compress the anterolateral surface of the
M
pontom edullary junction, where the
Hi
posteroinferior cerebellar artery origi­
nates. W hen the vertebral artery was
I IS
detached from the medulla oblongata,
an indentation caused by the artery was
visible. The root entry zone of the VIHth
cranial nerve was exposed, but no ab­
norm ality was found. W e suspected that
vertebral artery compression of the me­
dulla oblongata might be responsible
for the patient's symptoms, so the artery
was shifted. A thin, 4- X 22-mm piece of
Gore-Tex (W .L. Gore & Associates, Inc.,
Flagstaff, A Z ) was passed under the
vertebral artery just p>roximal to the pos­
teroinferior cerebellar artery origin. A
6-0 nylon suture was passed through *
led
two slits made in the dura mater over
the jugular tuberculum and tied to the
Gore-Tex sheet to detach the vertebral
artery from the medulla oblongata,
IS:
which achieved vascular decompression
(Fig. 4). Throughout the procedure, the
somatosensory evoked potential re­
mained unchanged.

a flow void in the
right side of the
m edulla oblongata,
w h ich indicates
severe vascular
com pression

B, postoperative M R I scan dem onstrating that this void is no longer

visible and indicating good decom pression of the m edulla oblongata.

w

Indentation, apparently caused by the
vertebral artery, was noted on the me­
dulla where the right hypoglossal nerve
originates, and the right vertebral artery
was clearly indented by the hypoglossal
nerve. The VUIth, IXth, Xth, and Xlth
cranial nerves were all spared.
Postoperative course
The postoperative neurological exam­
ination revealed that hypalgesia had
subsided, and the patient had a feeling
of fatigue in his right arm and leg. The
atrophy of the right sternocleidomas­
toid and supraspinatus muscles re­
mained. The postoperative M R I scan re­
vealed good decompression of the
medulla oblongata (Fig. IB ). The patient
was discharged 2 weeks after surgery.
His symptoms gradually decreased, and
he returned to his previous work 6
months after surgery. He has remained

healthy in the almost 9 years since the
operation.

Patient 2
A 47-year-old man, the master of a
sushi shop, first complained of vertigo 7
years before presentation. One year
later, he noticed difficulty hearing on
his left side. In March 1996, his gait was
unsteady and he could not stand w ith ­
out holding onto a bar. At that time, he
was referred to us by an otolaryngologist.
Exam ination
At admission, the patient was deaf in
his left ear and had a decreased gag
reflex on the left side. Standing on his
left foot and maintaining a tandem gait
were impossible because of left cerebel­
lar dysfunction. Preoperative M R I re­
vealed a tortuous left vertebral artery
compressing the left anterolateral side
of the medulla oblongata, resulting in
deformity of the medulla oblongata (Fig.
5A). On the basis of the neurological and
M R I findings, his symptoms were
thought to be caused by the vertebral

V

F IG U R E 3. T2weighted MRI
scans of Patient 2.
A, preoperative
M R I scan revealing
the left-sided
deformity of the
medulla oblongata
with the vertebral
F IG U R E 2. Vertebral angiogram of

artery attached to

Patient 1, revealing tortuous vertebral

the medulla, ft

arteries bilaterally and the point of

postoperative M R I scan dem onstrating space betw een the vertebral artery and the

m edulla com pression (a rro w h e a d ).

m edulla oblongata, w h ich indicates that vascular decom pression was achieved.

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Jral

th
icle
>rti

ien
!■/
iei
ki

icti,

to

C o m p r e s s io n o f th e M e d u lla O b lo n g a t a b y th e V e r t e b r a l A r t e r y

FIGURE 4. Intraoperative photographs of Patient 2. A , the tortuous vertebral
artery (VA) compressing the m edulla oblongata. B, the vertebral artery is shifted
away from the m edulla oblongata w ith a Gore-Tex sheet and 6-0 nylon suture,
which is anchored to the dura m ater near the jugular tuberculum .

Postoperative course
The patient's postoperative course
was uneventful. The gag reflex seemed
normal, and his cerebellar dysfunction
decreased; he could stand and w alk
without holding a bar. The postopera­
tive MRI scan revealed that the vertebral
artery was detached from the medulla
oblongata, although some deformity of
the medulla remained (Fig. 3B). He was
discharged 2 weeks after surgery and
returned to his previous job 3 months
later.

d is c u s s io n

Patient 1 presented with progressive
pyramidal tract signs and lower cranial
nerve deficits. The M R I scans and ver­
tebral angiograms revealed compres­
sion of the medulla oblongata by a tor­
tuous vertebral artery. The right
vertebral artery was thought to be com­
pressing both the corticospinal tract just
below the pyramidal decussation and
the nucleus solitarius in the anterolatt rul portion of the medulla, causing the
n£ht hemiparesis and difficulty swalowing. A surgical decompression was
Performed with good results. Patient 2
presented with left hearing loss, de­
ceased gag reflex, and left cerebellar
ysfunction. There were no pyram idal
hact signs. The medulla oblongata was
apparently compressed by a tortuous

vertebral artery, especially at its antero­
medial side. The inferior olive and the
olivocerebellar tract, as w ell as the nu­
cleus ambiguus, were thought to be dis­
turbed. Surgery was performed after ob­
taining informed consent from the
patient regarding the benefits and pos­
sible risks of surgery. The reason for his
hearing disturbance was not fully deter­
mined. Because the cerebellar signs dis­
appeared after surgery, the tortuous
vertebral artery may have been com­
pressing the inferior olive and the olivo­
cerebellar tract at the level of the me­
dulla oblongata. In both patients, the
symptoms disappeared almost com­
pletely after surgery, and both patients
returned to their previous jobs.
There are few reports describing a tor­
tuous vertebral artery compressing the
medulla oblongata and causing neuro­
logical deficits, such as pyram idal tract
signs or lower cranial nerve deficits. In
1985, Kim et al. (5) reported the first
such case. Their patient responded well
to vascular decompression. Kobayashi
et al. (6) reported a patient with com­
pression of the medulla oblongata by
the vertebral arteries bilaterally associ­
ated with a Chiari malformation, in
which the symptoms improved after
vascular decompression of the medulla
oblongata. Except for the patient re­
ported by Tanaka et al. (10), in whom
the involved artery was an excessively

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909

long basilar artery, the vessel responsi­
ble is usually a tortuous vertebral artery,
but never one with a "m egadolicho"
shape.
It is not easy to determine when sur­
gery is indicated. For hemifacial spasm
or trigeminal neuralgia, surgical micro­
vascular decompression is indicated by
the clinical status, even when no appar­
ent offending vessels are observed on
M R I scans or magnetic resonance angio­
grams. On the other hand, in symptom­
atic patients in whom compression of
the medulla oblongata by the vertebral
artery is suspected, a definite diagnosis
should be made with the aid of M R I as
well as with a precise neurological ex­
amination. In our two patients, the de­
formity of an apparently compressed
medulla oblongata was visible on the
M R I scans.
There are several possible methods of
surgical vascular decompression. Sim ­
ply inserting a prosthesis between the
brainstem and the offending vessel can
usually decompress the typical hemifa­
cial spasm or trigeminal neuralgia.
However, with compression of the me­
dulla oblongata by the vertebral artery,
the offending artery may be thick and
quite difficult to decompress by this
method. Fukushima (3) and Kondo (7)
proposed lifting and anchoring the of­
fending vessel to the nearby dura mater
with a variety of materials. In our cases,
the tortuous vertebral artery was shifted
and anchored to the dura mater with a
Teflon sheet in Patient I and Gore-Tex
in Patient 2, without inserting a prosthe­
sis. Good vascular decompression was
achieved, which improved the neuro­
logical deficits. The vertebral artery
should be shifted carefully, to avoid
damaging small branches or perforating
arteries from the vertebral artery enter­
ing the medulla oblongata. W e previ­
ously reported a patient treated by sec­
tioning the tortuous vertebral artery to
produce vascular decompression of the
medulla oblongata (4). This is the ulti­
mate w ay to achieve vascular decom­
pression, but indications for this ap­
proach may be quite limited. Shifting
the vessel and anchoring it to the dura
mater is a more appropriate choice.
In conclusion, careful examination us­
ing M R I may help diagnose this rare
lesion more frequently. A precise diag-

910

Hongo et al

nosis on the basis of both M R I and a
careful neurological examination is es­
sential to determine appropriate surgi­
cal interventions.
R e c e iv e d , D e c e m b e r 17, 1998.
A c c e p te d , Ju n e 7, 1999.
R e p rin t req uests: K a z u h iro H o n g o , M .D ., D e ­
p a rtm e n t of N e u ro s u rg e ry , S h in sh u U n iv e rs ity
Sch o o l o f M e d ic in e , A s a h i 3-1-1, M a ts u m o to
390-8621, Ja p a n .

R EFER EN C ES
1. Deleted in proof.
2

. Dohi K, Kubota M , Ham ada H, Kuwabara K,
Nishijim a Y, Kushihashi T, Matsum oto K: Com ­
pression of the medulla oblongata by a dissect­
ing aneurysm of the vertebral artery

7

years

after its rupture: Case report [in Japanese]. No
Sh in k ei G eka 2 2 :1 0 6 7 - 1 0 7 0 , 1 9 9 4 .
3

. Fukushima T: Posterior cranial fossa neurovas­
cular decompression (Jannetta method) for tri­
geminal neuralgia and facial spasm [in Japa­
nese]. No Sh in k ei G eka 1 0 :1 2 5 7 - 1 2 6 1 , 1 9 8 2 .

4

. Hongo K, Kobayashi S, Hokam a M, Sugita K:
Vertebral artery section for treating arterial
compression of the medulla oblongata: Case
report. J Neurosurg 7 9 :1 1 6 - 1 1 8 , 1 9 9 3 .

5

. Kim P, Ishijima B, Takahashi H, Shim izu H,
Yokochi M: Hem iparesis caused by vertebral
artery compression of the medulla oblongata:
Case report. J Neurosurg 6 2 :4 2 5 ^ 4 2 9 , 1 9 8 5 .

6

. Kobayashi

T,

Ogawa

A,

Kam eyam a

M,

Uenohara H, Yoshimoto T: Chiari malformation
w ith compression of the medulla oblongata by
the vertebral arteries: Case report. J Neurosurg
7 7 :3 0 7 - 3 0 9 , 1 9 9 2 .
7

. Kondo A: Follow-up results of m icrovascular
decompression in trigeminal neuralgia and
hemifacial spasm. Neurosurgery 4 0 :4 6 - 5 2 , 1 9 9 7 .

8

. M iyazaki

M,

Hashimoto

T,

Sakuram a

N,

Yoshimoto T, Tayama M , Kuroda Y: Central
sleep apnea and arterial compression of the me­
dulla. A nn N eurol 2 9 :5 6 4 - 5 6 5 , 1 9 9 1 .
9

. M urata

H, W aga S, Kojima T, Shim izu T,

Shim izu S: M edulla oblongata compression by
a tortuous vertebral artery: Case report [in Jap ­
anese], No Sh in k ei G eka 2 3 :3 4 9 - 3 5 3 , 1 9 9 5 .
1 0 . Tanaka Y, M iyazaki M , Tsuda M , M atsuyam a
M , Kuzuhara S: Compression of the medulla
oblongata by an elongated vertebral artery [in
Japanese]. Sh in k ein aik a 3 4 :3 3 5 - 3 3 6 , 1 9 9 1 .

C O M M EN TS
The authors report the successful
treatment of two patients who were rel­
atively young and who presented with

symptoms suggestive of lower brain­
stem dysfunction. Imaging studies were
reasonably correlated w ith neurological
signs and suggested encroachment by
the aberrant course of a vertebral artery.
The authors' illustrations and intraoper­
ative photographs demonstrate a nice
technique for displacing the vertebral
artery from the brainstem. This unusual
condition, as well as potential treatment
alternatives, has been described previ­
ously, but the authors supplement the
existing literature with useful surgical
recommendations. M y typical experi­
ence has involved older patients with
ectatic vertebral arteries that produced
the mass effect. The expected perioper­
ative course in elderly patients can be
expected to be more difficult than that
reported in this article. In addition, in
patients with more advanced and dis­
abling neurological symptoms, the dis­
section and displacement of the artery
from the brainstem is not as well toler­
ated and has a higher morbidity. N e v­
ertheless, anecdotal evidence suggests
that this condition can be progressive,
and therefore treatment is warranted. I
plan to use the Gore-Tex sling, as re­
ported by the authors, in my own
practice.
H. H unt Batjer
Chicago, Illinois
I read with interest these two unusual
case reports by Hongo et al. from Aichi
Medical University. Symptomatic vas­
cular compression of the medulla by a
tortuous vertebral artery has been re­
ported previously. This rare condition
presents several challenges to neurosur­
geons. As outlined by the authors, a
careful neurological examination is im ­
perative to ensure that the patient's
symptoms are attributable to vascular
compression of the brainstem. In the era
of magnetic resonance imaging, it is not
uncommon to identify asymptomatic
distortion of the brainstem caused by a
tortuous vertebral or basilar artery. In

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the clinical decision-making process, the
neurosurgeon must determine whether
the patient's symptoms are significant
enough to warrant surgical interven­
tion. Each of the patients reported b\
Hongo et al. had significant and pro­
gressive
neurological deficits that
clearly justified surgical intervention.
The surgical management of this partic­
ular disorder is much more complicated
than microvascular decompression for
cranial nerve dysfunction. These risks
must be weighed when considering sur­
gical intervention. Finally, the technical
aspects of vascular decompression of
the medulla are formidable. As pointed
out by the authors, simple placement of
a prosthetic device between the artery
and brainstem is inadequate treatment.
More often, the artery must be displaced
from the brainstem by creation of a sling
to the adjacent dura. Care must be taken
to avoid injury to small perforating
branches off the vertebrobasilar system.
These authors have presented an impor­
tant report and have achieved excellent
surgical results in these two patients.
D an ie l L. Barrow

Atlanta, Georgia
Tortuosity of the vertebral and basilar
arteries is the rule rather than the excep­
tion. It is unusual, however, for such
tortuosity to cause clinical symptoms.
Patient 1 in this article is a compelling
example of such a vascular compression
syndrome. Patient 2 is less compelling,
although the M R I scans are quite dra­
matic. The authors are correct in em­
phasizing the need for careful patient
selection before any operative decom­
pression. M oving large, tortuous pos­
terior circulation vessels is more haz­
ardous than the typical superior
cerebellar artery manipulation in tri­
gem inal neuralgia. The Gore-Tex sling
is an innovative w ay of managing this
problem.
Ste ve n L. Giannotta

Los Angeles, California