Digest of Spine Surgery Journal
2015. N 2. С. 13–16
© A.Yu. Mushkin et al., 2015
PROCESSUS OCCIPITO-VERTEBRALIS:
А RARE SUBOCCIPITAL ABNORMALITY
WITH DIFFERENT CLINICAL SIGNS*
A.Yu. Mushkin1, E.V. Ulrich2, A.V. Gubin3, V.P. Snischuk1, 4
Petersburg Research Institute of Phthisiopulmonology, St. Petersburg, Russia
2St. Petersburg State Pediatric Medical University, St. Petersburg, Russia
3Russian Research Center of Reparative Traumatology and Orthopaedics n.a. acad. G.A. Ilizarov, Kurgan, Russia
4Leningrad Regional Children’s Clinical Hospital, St. Petersburg, Russia
1St.
The paper presents three cases of similar pediatric bony abnormality at the craniovertebral junction accompanied by torticollis and ischemic brain attacks. Two patients were operated on, and the outcomes are analyzed. Type of Publication: case
series study. Level of Evidence – IV.
Key Words: torticollis, osteal torticollis, proatlas, atlantooccipital bone, cervical spine abnormalities, surgical treatment,
neck, cranio-vertebral abnormalities.
*Mushkin AYu, Ulrich EV, Gubin AV, Snischuk VP. [Processus occipito-vertebralis: а rare suboccipital abnormality with
different clinical signs]. Hirurgia pozvonocnika. 2015;12(2):40–43. In Russian.
Due to the peculiar anatomy of the
suboccipital region, which provides
functional support of the head, allows
a great deal of rotation and protects
elements of the central nervous system
and vessels, the craniovertebral junction
is considered as the most unique part of
the human skeleton.
The unusual structure of the Oc–C1–
C2 complex is confirmed by the features
of its embryologic development: the
complex is formed from 6 sclerotomes
that further differentiate into 14–16
ossification centers and after functional organization and sclerotomal resegmentation give rise to the cervical vertebrae [3]. It is no coincidence that this
extremely complex and unstable process
is accompanied by occurrence of multiple malformations, most of which, however, are asymptomatic or develop with
minimal complaints. This may explain
the fact that the majority of publications
devoted to craniovertebral dysplasia is
limited to the description of the anatomical features during their radiologic
examination. The clinical manifestations
of the disease generally refer to by a collective term “vertebrobasilar insufficiency” and are usually accompanied by signs
of circulatory disorders in the basin of
the vertebral arteries (so-called vertebral artery syndrome) or neurological
disorders at dislocations of Oc–C1 and
C1–C2 segments. Orthopedic pathology,
which is the leading sign of craniovertebral dysplasia, occurs quite rare, except
for severe abnormalities.
In different years, we have observed
three patients with the same type of craniovertebral abnormality who had similar
radiological features and different clinical signs. We have not found publications
devoted to this pathology. We gradually accumulated experience and technical facilities for the surgical treatment
of neck diseases in children; hence we
treated these patients in different ways.
Our retrospective experience may be of
interest to specialists.
Case description 1 (2007). A boy aged
11 was considered healthy. During rapid
growth, the mother noted the appearance and progression of torticollis and
facial asymmetry. At residence, he was
diagnosed with “chronic subluxation
of C1”. Cervical halter traction, correction with a Philadelphia cervical collar, and physiotherapy gave no success.
The patient was examined 1 year after
the onset of the disease (Fig. 1a). 3D-CT
imaging revealed a bony process aris13
Spine deformities
ing from the occipital bone on the left
that formed nearthrosis with posterior
arch of C1 (Fig. 1b). Functional selective
angiography in head rotation to the right
revealed changes regarded as the compression of the right vertebral artery at
the level of C1 (Fig. 1c).
Supposing that the oblique position
of the atlas decreases the Ос–C1 distance
on the right at head rotation and causes
compression of a. vertebralis dex. and
since we considered risky an intervention in the region of the left vertebral
artery loop, we agreed on balancing posterior fusion Oc–С1. Before the operation we visually corrected deformity
of the cervical spine during 14 days by
halo traction with asymmetric traction
(load right 6 kg, load left 2 kg). Without removing traction, posterior occipitospondylodesis Ос–С1 was made with
a fragment of iliac crest autograft and
wiring.
The postoperative period was without
complications, the child achieved verticalization with a Philadelphia collar. Control functional angiography 2 weeks after
surgery revealed no signs of compression
of a. vertebralis dex. Examination after 1
year: torticollis removed, facial asymme-
Digest of Spine Surgery Journal
2015. N 2. С. 13–16
A.Yu. Mushkin et al. Processus Occipito-vertebralis: А Rare Suboccipital Abnormality with Different Clinical Signs
try preserved (Fig. 1d). The bone block
is formed.
Clinical case 2 (2009). A girl aged 6
was referred to the intensive care unit
due to a sudden depression of consciousness to soporose state. During history
taking, she was found to have previously
experienced repeat transient vertigo, episodes of collapse with a disorder of consciousness and sudden muscle hypotonia
that relived on their own in 1–3 hours.
These events were provoked by abrupt
rotation and flexion of the head to the
left. MRI of the brain showed a moderate
increase in the lateral and third ventricles
to 15 and 16 mm, respectively, but without occlusion of liquor pathways.
On examination during verbal contact the patient is trying to open the eyes,
does not fix the eyes, and the eyeballs are
in the central position. Orbital fissure
and pupils OD = OS, poor consensual
light reflex. Face symmetrical, no paresis, and middle position of the tongue.
Severe general muscular hypotonia is
present. The patient responds to painful stimuli, the pain is localized. Tendon
reflexes are reduced and symmetrical.
Pathological meningeal symptoms are
absent. Liquor is without pathology, cell
count is 6/3. Focal changes in the fundus
are not revealed.
The condition was regarded as acute
cerebral ischemia. There was not possibility of urgent examination of the brain
vessels at the moment of admission; vascular therapy was started, which resulted
in a full recovery of consciousness within
a few hours. Routine multi-layer spiral
CT-angiography of the neck vessels and
base of brain revealed a bony process
(Fig. 2a, b) arising from the skull base on
the left and pressing into the external
surface of the anterior arch of the atlas.
Functional X-ray angiography of neck
vessels and brain showed normal patency
of common and internal carotid arteries.
The right and left vertebral arteries in the
middle position of the head are patent,
but functional tests (rotating the head
to the left) showed complete occlusion
of the right vertebral artery at the level of
the atlantooccipital membrane (Fig. 2c).
During normalization of the child’s condition the parents categorically refused
any additional examinations, took the
child from the hospital and the child was
lost for follow-up.
Case description 3 (2014). A girl aged
12 complained of head flexion restriction
to the left and discomfort in the neck,
b
а
c
d
Fig. 1
The patient aged 11: a – appearance on primary examination: torticollis and facial
asymmetry; b – 3D-CT of the suboccipital region (front view): bony process of the
occipital bone that forms neoarthrosis with C1 on the left; c – angiography findings
regarded as compression of the vertebral artery at the head rotation (arrow), a
retrospective analysis suggests that this conclusion could be wrong and in real the
effect of the compression is due to skiagraphs of artery loop elements; d – appearance
of the patient 1 year after the operation
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Spine deformities
which were increasing in the last two
years. The mother noted a slight asymmetry of the face and head position for
the first time at a preschool age; this did
not cause any subjective complaints and
was regarded as a consequence of congenital muscular torticollis. The parent
related the complaints with increasing
attention at puberty to her appearance,
as well as active rehabilitation treatment
recommended by physicians, including
neck massage and therapeutic physical
training with forced neck flexion. Radiographs of the cervical spine, including per
os, identified no clear pathology, except
for an oblique position of the skull base
in relation to the vertical axis of the cervical spine in anterioposterior radiograph
(not present due to the low informativity), which was also regarded as a sign of
muscular torticollis consequences.
CT of the craniovertebral junction posterior of the left mastoid bone
revealed a massive, vertically oriented
conical bony formation, which arises
from the occipital bone and the top is
connected to the external surface of the
posterior arch of the atlas (Fig. 3a). CT
angiography (Fig. 3b) clearly shows that
the formation is adjacent to the vertebral
artery at a considerable distance, without
causing its stenosis, which is confirmed
by Doppler examination with functional
tests. Due to lack of neurological and
vascular symptoms of the craniovertebral instability and subjective desire of
the girl to improve her appearance, we
decided to remove the abnormal bone
with simultaneous release of the vertebral artery.
The patient was positioned on the
stomach with pre-marked abnormality
in the posterolateral projection of the
neck (Fig. 3c). Linear incision was used
to expose the atlantooccipital bone with
adjacent parts of the occipital bone and
the left half of the posterior arch of С1. At
its medial edge, the vertebral artery was
visualized, which was protected from the
abnormal bone by turunda and neurosurgical spatula. The bone was removed
using bone nippers and high-speed drill
on all the way to the inner cortical plate,
which, in turn, was resected using Kerrison forceps of small size.
Digest of Spine Surgery Journal
2015. N 2. С. 13–16
A.Yu. Mushkin et al. Processus Occipito-vertebralis: А Rare Suboccipital Abnormality with Different Clinical Signs
The surfaces of the occipital bone and
the arch of C1 in contact with the abnormality were treated with bone wax. Over
the intervention area, posterior atlantooccipital membrane was well visualized
with vertebral artery passing through. A
suture in layers was applied.
а
The patient underwent immobilization in a Schantz collar in the early
postoperative period only during activation of pain. Postoperative CT scans are
shown in Fig. 3d. Two and six months
after the operation there were no subjective complaints, mild asymmetry in
b
c
Fig. 2
Female patient aged 6: 3D-CT reconstruction (a), 3D-CT angiography (b) and
radiographic angiography of the neck (c): bonyprocess that arises from the occipital
bone and the top of the bony process presses into the external surface of C1 lateral
to the loop of a. vertebralis; obstruction of the right vertebral artery in head rotation
а
c
b
d
Fig. 3
Female patient aged 12: a – 3D-CT reconstruction in posteroanterior projection: bony
process of the occipital bone forms neoarthrosis with C1, oblique position of the head;
b – coronal and axial CT views showing the arrangement of the vertebral artery at
the medial edge of the bony formation; c – the projection of palpable pathological
bony formation posterior to proc. mastoideus; d – 3D-CT reconstruction of the
craniovertebral area after the operation
15
Spine deformities
the position of the head retained, however, volume of movements significantly
increased, especially of lateral flexion.
Thus, in all three children the same
abnormality was identified characterized
by a bony formation arising from the
occipital bone and pressing into the C1
vertebra. In all cases, the anomaly was
manifested in different major clinical
symptoms: late progressing torticollis
(case 1), acute transient cerebral ischemia (case 2), and restriction of head
rotation and events of discomfort (case
3). The clinical manifestation of the disease in the first case resulted from the
growth of the child at puberty, in the second case from abrupt head rotation, and
in the third from the child growth in prepubertal period and active rehabilitation
treatment recommended by physicians.
Similar to an omovertebral bone,
which is a bony connection which is
not present in the norm, but is present
between the elevated scapula and one of
the cervical vertebra in Sprengel’s deformity, the considered pathology may be
referred to as an atlantooccipital bone,
although, perhaps, it will be more correct
to consider it as the vertebrate process of
the occipital bone (processus occipitovertabralis). In our opinion, the originality of the pathology, especially the size
and position of the bony formation significantly distinguishes it from known
descriptions of proatlas, manifestation of
atlas or atlanto-occipital synostosis [1, 2,
4, 5], although they are likely to have the
same embryogenesis. This bony abnormality causes secondary orthopedic manifestations (torticollis) and vascular disorders, and the extent of clinical signs
differs significantly in each case.
As for surgical approach, most likely, the operation in the third case is the
most justified. However, the decision for
such intervention should be based on the
full radiographic examination to evaluate the ratio of bone, vascular and brain
structures in the area of the abnormality
(CT-angiography is the most informative,
including 3D-reconstruction and functional tests), the technology and surgical instrumentation that permit minimal
traumatization during the operation.
Digest of Spine Surgery Journal
2015. N 2. С. 13–16
A.Yu. Mushkin et al. Processus Occipito-vertebralis: А Rare Suboccipital Abnormality with Different Clinical Signs
Литература/References
Address correspondence to:
Mushkin Aleksandr Yuryevich Politekhnicheskaya str., 32,
St. Petersburg, 194064, Russia, [email protected]
1. Veselovskiy V.P., Mikhaylov M.K., Samitov O.Sh. Diagnosis of syndromes of spine
osteochondrosis. Kazan, 1990. In Russian.
2. Vetrile S.T., Kolesov S.V. Craniovertebral Pathology. Moscow, 2007. In Russian.
3. Brockmeyer DL. Anvanced Pediatric Craniocervical Surgery. NY, 2006.
4. Clark CR, ed. The Cervical Spine. 3rd ed. Philadelphia, 1998.
5. Heary RF, Albert TJ, eds. Spinal Deformities. The Essentials. NY, 2006.
Aleksandr Yuryevich Mushkin, MD, DMSc, Prof., St. Petersburg Research Institute of Phthisiopulmonology, St. Petersburg; Eduard Vladimirovich Ulrikh, MD, DMSc,
Prof., St. Petersburg State Pediatric Medical University; Aleksandr Vadimovich Gubin, MD, DMSc, Russian Research Center of Reparative Traumatology and Orthopaedics n.a. acad. G.A. Ilizarov, Kurgan; Viktor Pavlovich Snischuk, MD, St. Petersburg Research Institute of Phthisiopulmonology, Leningrad Regional Children’s Clinical
Hospital, St. Petersburg, Russia.
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Spine deformities