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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6029_Библиотеки_им_академика_М_И_Перельмана.pdf
Surgical Approaches
P. Suchomel, J. Hradil, and R. Fricˇ
In the majority of procedures in CVJ, the surgical field
should lie slightly higher or at the level of right cardiac
atrium. The operating table should allow position changes
in up and down directions in case of uncontrollable
bleeding or, conversely, to prevent possible venous air
embolism. CVJ region, intentionally set higher than
heart, represents predisposition to venous air embolism,
and adequate precautions such as central venous line and
transesophageal echocardiography monitoring should be
considered. On the contrary, the lower position of the
surgical field may predispose to increased venous bleeding from epidural venous plexuses and veins surrounding
C2-roots. Majority of surgical procedures in UCS have
to be performed under guidance with fluoroscopy. X-ray
visibility of target bony structures must not be compromised by operating table or any other hardware. Surgical
position should not interfere with anesthesiological
equipment, especially with reinforced tubes securing airways. To retain preoperative stability but also to reduce
possible UCS deformation, the head is often fixated in a
Mayfield three-point clamp (Fig. 4.1). When performing
a rigid fixation of the head, appropriate position of
patient’s body has to be considered, particularly in cases
where the body can counteract by its weight. When a
controlled axial skeletal traction is needed, it is better to
use a halo ring or other freely adaptable skull fixation
clamp than the table-fixed Mayfield clamp. Last but not
the least, the surgical position should allow the surgeon
4
Fig. 4.1 Preparing of the patient for posterior UCS surgery.
Notice the attached IOM electrodes
to operate in an ergonomic and physically comfortable
position. The overall setting of the operation theater
should enable the use of extensive surgical armamentarium, surgical microscope, and other devices that are
commonly used in contemporary surgical techniques
(C-arm, navigation workstation, electrophysiological
monitoring etc.). Many surgical approaches to CVJ and
UCS area have been used and myriad access variants
used mostly by neurosurgeons to reach tumors, vascular
anomalies, and other CVJ pathologies have been reported.
Most of those intended to decompress the neural structures are however not suitable for reconstruction of the
spine and CVJ. In the following text only those approaches
suitable for spinal procedures will be described in detail.
P. Suchomel () and J. Hradil
Department of Neurosurgery,
Neurocenter, Regional Hospital Liberec,
Husova St. 10, 46063 Liberec, Czech Republic
R. Fricˇ
Department of Neurosurgery,
Rikshospitalet, Oslo University Hospital,
Sognsvannsveien 20, 0027 Oslo, Norway
P. Suchomel and O. Choutka, Reconstruction of Upper Cervical Spine and Craniovertebral Junction,
DOI: 10.1007/978-3-642-13158-5_4, © Springer-Verlag Berlin Heidelberg 2011
4.1 Posterior Midline Approach
This is the most traditional, the simplest, and truly the
most often used approach to the region of UCS and
CVJ. It is suitable for simple decompression of the
39
40
Fig. 4.2 Artistic drawing of structures visible from posterior
midline approach
neural structures (in trauma, Chiari malformation, etc.)
and is also commonly used to access the spinal cord
and structures in posterior fossa. The posterior midline
approach (Fig. 4.2) is, in principle, the easiest and safest approach for different techniques of posterior fixation (see Chap. 6) and therefore, it is most frequently
used for UCS reconstruction and/or stabilization.
4.1.1 Surgical Technique
Patient positioning largely depends on the type of the
surgery. The specific types of surgery require specific
positions. To limit the risk of venous bleeding, so called
“landing Concorde” setting with the lowered position of
the body and lower limbs flexed in knees can be of
advantage. The “braking horse” position with straight
neck and flexed UCS performed under lateral fluoroscopy enables an adjustment of the correct angle for C1-2
transarticular screw fixation. Nevertheless, no general
rules can be given and surgeon’s individual preference
and experience often plays the most important role.
The posterior midline incision typically extends from
the inion to the spinous process of C3. The surgeon
advances along the nuchal ligament, preferably using a
monopolar electrocautery. The dissection of the upper
portion of the wound does not vary from that in cranial
procedures, detaching nuchal insertions to the posterior
skull base to achieve a proper exposure of the occipital
squama. The external occipital protuberance is identified. SNL and INL muscle attachments are dissected
and retracted laterally using bended self-retaining (“posterior fossa”) retractors. Continuing along the midline
4 Surgical Approaches
caudally, the spinous process of C2 is, usually, clearly
palpable. Subperiostal exposure of lateral walls of C2
lamina allows the introduction of the second angled
retractor caudally, e.g., opposite to the first one.
The posterior atlantal tubercle is the most important
anatomical landmark. Its muscle attachments are
sharply cut off and subperiostal dissection continues
laterally, first along the inferior border of C1 lamina.
This is a very important step to avoid potential injury
to VA in C1 posterior groove, especially if bone ponticuli are present as described in Chaps. 1 and 6.
The extent of the exposure and dissection of muscular attachments should be limited only to expose the
desired target structure. Muscle connections to the
spinous process of the C2 are biomechanically important. However, for most open procedures and surgical
techniques in this area, the dissection of muscular
detachments is unavoidable.
4.2 Posterior Paramedian Approach
This route is used mostly in minimally invasive procedures in the subaxial spine. There are not many indications for this approach in the region of the UCS.
However, as minimally invasive techniques become
more common, lateral paramedian incisions can be
used for screw introduction via tubular retractors, particularly in case of percutaneous surgical techniques
(Figs. 7.6 and 7.7; Chap. 7).
4.3 Lateral Approaches
There are several versions and numerous modifications
of lateral and posterolateral approaches such as farlateral or extreme-lateral. In neurosurgery, far-lateral
approach stands for a low suboccipital approach that
extends up to the occipital condyle and atlas, but it
does not include removal of these structures [32]. Its
caudal extensions merge with procedures designed
specifically for the UCS.
4.3.1 Posterolateral Approaches
These approaches are primarily designed for decompressive procedures and tumor resections. The surgery
4.3 Lateral Approaches
41
should not destabilize the UCS. The anatomy is complex and the course of the VA represents a major
obstacle. Different surgical techniques have been
described in detail, most of them introduced by neurosurgeons [3, 9, 22, 23, 54, 61, 69]. However, once the
surgical dissection affects the natural stability of the
spine, the reconstruction may be troublesome.
Resection of 50% of occipital condyle may increase
the flexion/extension movement by 153%, lateral
bending by 41%, and rotation by 28% [73]. All posterolateral reconstruction techniques involve unilateral
occipitocervical fixation, which does not provide sufficient primary stability. On the other hand, a substantially better functional outcome may be achieved when
the C0-C1 joints are adequately preserved [66].
Because of the issues mentioned above, we do not use
posterolateral approach as a primary route to reconstruct the UCS.
4.3.2 Lateral Approach for C1-C2 Transarticular Fixation
There are several early notes describing lateral
approach to the region of UCS. Henry (1957) used a
sternomastoid eversion in order to reach important
structures of the UCS [31]. Whitesides (1966) described
an approach designed for the UCS fusion [76]. Barbour
(1973) gave description of a technique of transarticular
C1-C2 fixation and reported it being used since 1956.
As he noted, it is necessary to perform this approach
bilaterally, because unilateral fixation is not sufficient
[8]. DuToit and Blignaut employed Barbour’s technique in 1973 [20] and found it quite difficult to place
the screws accurately. Several modifications were
therefore suggested [20, 62].
4.3.2.1 Surgical Technique
The patient is positioned supine. For the purpose of the
approach, the head is turned away; however, it must
be realigned into the neutral position before fixation.
Original Barbour’s technique was very straightforward. The incision was an oblique line starting at the
anterior border of the mastoid process, passing down
over the palpable transverse process of C1 and running a little further behind the angle of the mandible
[8]. Anterior margin of the insertion of sternocleidomastoid muscle was identified. Advancing medially,
the surgeon cleared fascial cover and exposed the
transverse process of atlas. The accessory nerve,
which passes in a posteroinferior direction, was displaced, the transverse process was partially resected,
and paravertebral muscles cleared to expose the anterior aspect of the C1/C2 joint. The head was then
realigned to the neutral position before C1-C2 transarticular screw fixation was performed. The author
was concerned about too posterior dissection as it
could easily lead to injury of the VA or surrounding
venous plexuses.
After detailed cadaver studies, Du Toit suggested
several improvements. Transverse incision over the
base of the mastoid with extension downward and curving anteriorly along a neck crease was preferred for
better cosmetic result. Ear lobe was retracted anteriorly
and detachment of the sternocleidomastoid muscle
from its cranial insertion was suggested for better
exposure.
Roy-Camille [58] tried to avoid the muscle
detachment and inserted screws from a retro-SCM
approach. The authors admitted, nevertheless, frequent collisions of the drill and the trajectory of the
screws with the mastoid process. In the original Du
Toit’s setting, the transverse process of the C1 was
exposed by advancement just in front of the anterior
margin of the sternocleidomastoid muscle. Care
should be taken to avoid injury to the greater auricular nerve and external jugular vein during the exposure of the anterior border of the sternocleidomastoid
muscle. These structures are crossing obliquely in
upward and forward directions.
The accessory nerve is located 2–3 fingerbreadths
below the tip of the mastoid, running in posteroinferior
direction and it is hardly ever encountered during the
dissection. Posterior belly of the digastric muscle is
retracted anterosuperiorly in order to fully expose the
tip of the transverse process of the atlas. The occipital
artery and vein pass directly across the tip of the transverse process and should be mobilized and retracted.
Prevertebral fascia covering the process is incised and
subperiostally dissected along the anterior border of
the transverse process up to the lateral mass of the
atlas. Finally, the antero-lateral aspect of the lateral
mass is identified and cleared for insertion of the
screws. The head is realigned to the neutral position; a
proper adjustment of the joint has to be achieved and
secured by temporal fixation with a Kirschner wire
passing through the C1/C2 joint.
Drilling proceeds with an angle of 25° below the
horizontal plane and 10° behind the coronal plane
42
Fig. 4.3 Schematic picture of C1-2 transarticular screw intro-
duced from lateral approach
(Fig. 4.3). The authors used a special guiding device to
achieve proper angles and to protect surrounding structures while drilling. Twenty degrees in posterior direction was considered as the maximum safe angle to
avoid injury to the content of spinal canal. Navicular
bone screw was inserted and the joint was curetted and
packed with bone chips before final tightening. The
same procedure had to be performed contralaterally in
order to achieve a solid C1-C2 fixation.
4.3.2.2 Our Preference
We do not use the previously described approach for
UCS reconstruction because of its anatomical complexity and necessity for bilateral dissection. However,
the practical knowledge of the lateral approach can
surely be useful in certain indications, such as in case
of radical tumor removal.
4.4 High Anterolateral Approach
High anterolateral cervical approach is derived from
the subaxial access described to reach C3-T1 spine
[64]. DeAndrade and McNab [16] developed the cranial extension of standard approach to reach C1-2 area.
McAfee et al. suggested transecting the digastric
4 Surgical Approaches
muscle and resecting the submandibular gland in order
to enlarge the previously described access [45]. In
order to directly expose the atlantoaxial joints for
intraarticular cartilage debridement and to allow the
perpendicular transarticular C2 to C1 anterior screw
introduction, Vacaro et al. performed extensive rightsided high cervical approach accompanied by additional smaller incision on the left side [71]. Several
authors have advocated this approach (either mono or
bilateral) for treatment of different pathologies [55,
63]. However, lesions extending over the C1 level are
treated rarely [35]. Recently, this approach has been
successfully used in endoscopic resection of the
odontoid [77].
The anterior aspect of the UCS can also be approached
by a route passing behind the carotid artery [31, 75]. As
compared to the previously described “prearterial”
route, it is less straightforward. Although the connecting arteries and veins can be spared, the medial dislocation of the neurovascular bundle can be difficult and this
approach did not gain wide popularity.
4.4.1 Surgical Technique
In case of simple decompression of the UCS, the head
can be slightly rotated to the contralateral side in order
to achieve a better exposure. However, neutral head
position should be maintained when subsequent fusion
is planned. The skin incision is located either submandibularly or vertically along the sternocleidomastoid
muscle (STCM). Platysma is divided along its fibers,
the anterior border of STCM is dissected, and the muscle is retracted laterally. Then the anterior surface of
the spine can be approached between the neurovascular bundle medially and the pharyngeal wall laterally.
The parotid gland containing facial nerve tree is
retracted cranially, the digastric muscle is transected,
and the facial vein and external carotid artery branches
are ligated. Division of descending loop of ansa cervicalis from n. XII. allows cranial dislocation of hypoglossal nerve. Finally, the prevertebral fascia is sharply
cut and the longus colli muscle subperiostally is
exposed with the help of bipolar electrocautery.
Adequate release of the longus colli muscle is necessary for a safe anchorage of wound retractors beneath
the muscle. Elevation of pharyngeal wall in a cranial
direction enables direct visibility of anterior C1 arch.
4.5 Transoral Approach
43
4.4.2 Our Preference
The greatest advantage of high anterolateral cervical
approach is its anatomical similarity to the anterior
approach to subaxial cervical spine, which most of the
spine surgeons are very familiar with, performing it on
a daily basis. Furthermore, no potentially infected cavity is opened during this approach and the use of metal
implants is therefore safe. Difficulty can be encountered in case of low position of the mandible or immobile degenerative spine. Postoperative swallowing
difficulties are frequent, though most often temporary.
At our institution, the high anterolateral approach is
most frequently used in cases of UCS injury. The graft
and anterior plate is typically used in dislocated hangman’s fracture to fixate C2/3 segment (Figs. 12.14 and
12.18, Chap. 12). When performing the odontoid screw
fixation, we do not need a large exposure and oblique
approach starting at the C4/5 level suits well. Nearly
all pathologies of C2 vertebra can be treated by this
retropharyngeal approach, including palliative resection of tumors, evacuation of inflammatory tissue, and/
or C1-2 or even C0-1-2 transarticular fixation in case
of instability (Figs. 14.2 and 14.3, Chap. 14). Major
drawbacks of this approach are the oblique view of the
spine where estimation of the midline may be difficult
(Fig. 4.4), impossibility to expose the clival region,
and limited radicality in tumor resection. The exposure
achieved by this approach is frequently compromised
by the mandibular angle.
4.5 Transoral Approach
Transoral surgery is defined as a procedure carried out
through the oral cavity to gain access to anterior midline structures of CVJ and UCS. Under normal conditions, the surgeon should be able to expose the area
from the lower rim of clivus cranially to the level of
disk space C2-3 caudally.
The simple transoral approach can be extended
upwards by transsection of the maxilla or downwards
by splitting the mandible. Currently, minimally invasive and endoscopic techniques are increasingly used.
4.5.1 Transoral-Traspharyngeal
Approach
Fig. 4.4 Artistic drawing depicting the limited oblique visibility
of UCS during high anterolateral cervical approach
The first documented transoral (TO) surgery was performed by Kanavel (1919) who removed a bullet
located between anterior arch of atlas and a skull base
[39]. Scoville and Sherman (1952) studied the transoral route on cadavers and recommended its clinical
use for approach to the rim of FM [60]. Southwick and
Robinson successfully performed transoral removal of
C2 osteoma and evacuation of an abscess [64].
The first series of patients surgically treated by transoral route was presented by authors from Hong Kong
when Fang and Ong (1962) reported six cases of posttraumatic C1-2 dislocations and inflammatory process
in CVJ, respectively. Mullan et al. used the transoral
route for removal of tumors in CVJ [51]. Sukoff et al.
were the first who reported a successful transoral
decompression of the spinal canal in a case of myelopathy caused by rheumatoid disease [68].
Numerous papers dealing with this problematic
issue were published later [17, 33, 44, 56, 65]; most of
them case reports and small series of patients. The
main obstacles for a wider acceptance of the transoral
approach were: (1) need for special instruments, (2)
poor illumination, and (3) depth of the surgical field.
44
4 Surgical Approaches
The risk of infection was a big concern particularly in
cases when the subarachnoid space had to be opened.
The initial enthusiasm vanished after reports of high
frequency of meningitis and CSF fistulas, the complications with possible catastrophic sequelae. Some
other causes of high morbidity/mortality were also
reported [36, 38]. Only few surgeons continued to
develop the technique of transoral approach, trying to
reduce the frequency of complications [13–15, 28, 47,
48]. Crockard published his results from more than
350 transoral procedures in 1993 [13–15] and later
shared the lessons learned from his vast experience
[14]. He defined the pathologies indicated for transoral approach, described his technique, and emphasized possible risks. Frequency of infectious
complications was reduced to less than 3% in his
series. Hadley et al. reduced the perioperative mortality to zero [28].
Transoral approach is often necessary in case of
irreducible CVJ deformity where anterior pressure to
neural structures is present [48]. This situation may be
caused by a wide variety of disorders. From the historical perspective, the majority of cases were patients
suffering from rheumatoid arthritis where compression
caused by rheumatoid pannus was further enhanced by
posterior displacement of the odontoid. This indication
has become less frequent today because of studies
proving that atlantoaxial fusion alone can prevent not
only the vertical migration of the odontoid [26] but
also reduce the size of pannus (or even lead to its disappearance) [27, 49, 80, 82].
The other frequent indications for transoral route
include developmental or acquired deformities where
the anterior pressure cannot be reduced by simple
reduction; namely, an infection of the odontoid and its
surroundings can be a reason for TO intervention in
order to evacuate the pus and debride the infected tissue. Also, tumors can be biopsied or resected via transoral route.
Transoral decompression can induce significant
multidirectional instability of UCS and/or CVJ. This
applies particularly for cases with pre-existing partial
instability due to the disease itself, complete odontoidectomy, or transsection of the atlantal ligament
[18, 19]. Similarly, resection of the anterior arch of
atlas may influence the translational and particularly
the vertical stability of the CVJ [52]. The atlas loses its
anterior tension band. Due to its wedge-shaped profile, the lateral masses separate horizontally under the
vertical load caused purely by head’s weight and/or
rotations in the C1-C2 joint. Such mechanism is probably often responsible for development and progression of basilar impression. This condition can occur
after simple transoral odontoidectomy without fusion,
but even after vertically unstable posterior fixation
techniques such as with Lugue type rods fixed with
wires [53]. Precautions of atlas settling are twofold:
first, as recommended by Spetzler [65], not to resect
the anterior arch completely. Second, modern stable
posterior fixation constructs (plate/rod and screws)
have to be used. There were attempts to stabilize the
UCS anteriorly with plates in one session surgery [30,
41]. However, the biomechanical insufficiency of this
fixation [40] combined with the risk of hardware infection speak in favor of UCS stabilization from posterior
approach. Rare cases of complex surgeries, namely
tumor resections, result in total destabilization of CVJ
and require a reconstruction using a complex 360°
fixation [57, 67].
Current opinion on transoral procedures favors
direct extradural decompression which, however, is
inappropriate for intradural pathology. Watertight dural
closure is still an issue as potential risk of CSF leakage
and consequent infection is unacceptably high.
4.5.1.1 Anatomical Background
The transoral approach to the midline is generally
very safe as there are no important structures interposed (Fig. 4.5). Nevertheless, a detailed knowledge
of anatomy is mandatory, particularly when facing
anatomical variations during surgery. The pharyngeal
mucosa, constrictor muscles, prevertebral fascia, and
anterior longitudinal ligament are overlying the target area. The thickness of posterior pharyngeal wall
is approximately 4 mm above the level of C1 tubercle
and 6 mm above the level of the lateral masses and
central part of C2 [1]. Most of the authors use the midline splitting; however, the use of mucosal flap has also
been recommended [59]. Midline approach to anterior
aspect of UCS is safe. Once leaving the midline as in
flap technique, we have to keep in mind that important
structures must be protected by using a subperiostal
dissection. Cranially, care has to be taken not to injure
the XII nerve at its exit from the base of condyle and
the jugular foramen. Variant position of carotid artery
(deformed by subbasal kinking or coiling) can be very
4.5 Transoral Approach
Fig. 4.5 Artistic drawing of structures visible during simple
transoral approach
treacherous (Fig. 6.8, Chap. 6). Anterior tubercle of
the atlas is considered to be a crucial point for safe
dissection. The attachments of longus colli and longus
capitis muscles are less strong than the attachment of
anterior longitudinal ligament here.
Anterior arch of the atlas is approximately 30 mm
long, 15 mm high, and 6 mm thick. Usual working
space created by resection of the anterior arch is a little
smaller, reaching about 12–15 mm. Synovial joint with
fluid filled capsule can sometimes be encountered
behind the arch. The odontoid process is usually
20 mm (15–25.4 mm) long and slightly tilted posteriorly. The diameter at its base (“waist”) is approximately 9 mm (7.8–14.1 mm) and the maximal diameter
is 11 mm (8.4–14.1 mm). The expected distance of
vertebral artery from the midline is approximately
25 mm at the level of C1 and 11–15 mm at the level of
C2. Detachment of more or less damaged allar and
apical ligaments is necessary to release the odontoid
process. The crucial ligament, tectorial membrane, and
dura mater are located behind the resected odontoid.
While reaching the clival ridge one has to be aware
of venous sinus at its margin and possible venous
bleeding.
45
4.5.1.2 Surgical Technique
Neurosurgeons tend to perform a decompression of
neural structures first, followed by stabilization of the
CVJ, while orthopedic surgeons usually prefer to work
in reverse order. The extent of adequate exposure of
anterior surface of the CVJ and USC very much
depends on preoperative imaging and the extent of the
pathological process to be treated. As emphasized
above, all relevant radiological investigations should
be performed before planning the TO procedure.
Potential fixation points for the UCS stabilization have
to be defined before the surgery also. Simple transoral
procedure can be performed only if the patient’s orifice
can be opened wide enough to allow insertion of the
instruments. Minimal opening must be more than
2–3 cm [14, 48]. This is of special importance in RA
patients in whom the motion of mandibular joints is
often limited. The oral cavity must be free of infection,
including possible dental focuses which have to be
sanated. Prophylactic antibiotics should always be
administered. Corticosteroids are given in order to prevent soft tissue swelling and potential secondary damage to the spinal cord.
The majority of surgeons recommend intraoperative electrophysiological monitoring (IOM). Patients
are often intubated awake with the help of fiberoptic
guidance. Tracheostomy is performed only in very
complex surgeries with expected difficult postoperative course [50]. Some surgeons fixate the head into
three-point Mayfield type clamp, others use the “horse
shoe” support only. Oral cavity should be disinfected
very carefully. Different types of transoral distractors
are available to open the mouth and to push down the
tongue. The soft palate is often hindering the view. It
can either be split in the midline, leaving the uvula on
one side [48], or retracted up into epipharynx with the
help of a stitch attached to a rubber tube inserted transnasally [14, 28].
The incision site is usually infiltrated with a mixture
of local anesthetics and adrenalin. The optimal way of
mucosal incision is still being debated. A better visibility of target structures, more lateral exposure, and
easier wound closure advocate for use of broadbased
mucosa-muscle flap [59]. This so called U-flap may
be based either cranially [37] or caudally [43]. On the
other hand, U-flaps do not allow vertical extension
of the wound and more extensive lateral distraction
of the wound is often needed. Wound healing can be
46
4 Surgical Approaches
troublesome especially if ischemized during the surgery. Currently, most authors recommend a simple
midline incision starting at the anterior tubercle of
atlas [13–15, 28, 47, 48]. Lateral fluoroscopy is used to
determine the target part of the bone and also for final
estimation of the extent of resection. Filling the resection cavity with contrast medium can be helpful. Most
surgeons sit behind patient’s head while operating. Use
of microsurgical techniques is mandatory. The maximal safe lateral extent of subperiostal dissection is considered to be 40 mm at the level of C1 and 30 mm at the
level of the base of C2 [1]. The anterior arch of the atlas
is usually removed by high-speed drill and borders of
the odontoid are identified. The egg-shell type resection
of the odontoid is then performed starting either at its
tip or its base. Posterior remnants of the odontoid are
removed last. If dura has to be opened, watertight suture
is supplemented with patch and glue. Postoperative lumbar drainage seems to be mandatory if the risk of CSF
leakage and meningitis shall be minimized. Duration
of external lumbar drainage recommended varies from
only 4 days [28] to 10 days or more, as practiced by most
authors [13–15, 47, 48]. Final wound closure is recommended to be performed in two layers, e.g., muscle and
mucosa layer, but successful results after closure in
just one layer has also been described. Postoperatively,
the gastric tube is used for feeding for approximately
10 days. Depending on the type and the extent of surgery, some patients are left intubated for 2–3 days following the surgery. If indicated, posterior stabilization
may be performed either in the same session or it may
be postponed to a later time, while the patient is wearing
a halo vest fixation in the meantime.
4.5.2 Extended Transoral Approaches
Under normal anatomical circumstances, the classical
transoral approach (with or without splitting of the soft
palate) allows the surgeon to reach the lower edge of
clivus in a cranial direction and the C2/3 disk space in
a caudal direction. The lower third of clivus and part of
anterior C3 body surface can sometimes be exposed in
patients with large orifice. This variation may certainly
be helpful in some patients, but it is wise to be prepared
for a situation when the approach has to be extended.
When extending the simple transoral route to more
complex approaches to UCS and CVJ, several factors
have to be taken into account, including patient’s specific anatomical variations, size, location, and biology
of the lesion, whether en bloc or piecemeal resection is
intended, and last but not the least, the surgeon’s own
preference, most often given by his/her familiarity
with the procedure. Anatomical studies documented
that cranial or caudal extensions of transoral approach
not only increase the surgical field in vertical direction
but also make the operative field more superficial [81].
On the other hand, a need for more extensive dissection and potential surgical injury to structures such as
dental system possesses an increased risk of complications and/or worse functional outcome.
4.5.2.1 Transoral – Transmaxillar Approach
By this technique, the dissection plane is extended cranially, which is necessary for surgical targets located
above the level of the hard palate. It is the case in some
primary or secondary basilar invaginations/impressions or in platybasia where obtuse-angled clivus anatomically elevates the FM cranially. Tumors with
cranial extension, typically chordomas, may require a
surgical route providing the approach to intact part of
the clivus so that a radical resection can be achieved
(Fig. 7.1, Chap. 7, Fig. 20.13, Chap. 20).
Transfacial approaches had been used in maxillofacial surgery historically, but only in later years as a
route to the upper two-thirds of the clivus [4]. To reach
the clivus, Archer et al. [6] modified Le Fort I osteotomy (called as “Cheever’s operation”). Crockard [34]
developed a complex technique to get an approach to
lower clivus by adding a midline maxillary splitting to
Le Fort type maxillotomy and called the procedure an
“open-door maxilotomy”. In the largest published
series of patients operated on by transoral route (with a
remarkable number of developmental deformities), the
maxillary extension of the approach was reported to be
necessary in approximately 3% of cases [10].
4.5.2.2 Transoral – Transmandibular Approach
This approach is only seldom used in adult patients in
cases where a lesion, most frequently a tumor, extends
from C2 downwards below the level of vertebra C3.
Other indication is a limited opening of the mouth (less
than 2 cm) in patients where no other approach is
4.5 Transoral Approach
possible. The transmandibular route is very old
although it was originally developed for treatment of
oropharyngeal malignancies; its adaptation for upper
cervical spine surgery dates back to the early 1980s [5,
17]. Some of the authors use medial glossotomy [78,
81], some avoid it [12, 24, 25], but this decision is usu-
ally based on the character of the lesion and require
careful preoperative radiological analysis. There are
recent reports of this approach in children with complex developmental anomalies [11].
4.5.2.3 Our Preference
47
We tend to perform decompression first, followed by
stabilization procedure. Patients treated by transoral
route suffer from lesions causing an anterior compression, which cannot be reduced by traction or posterior
fixation alone. The indication becomes emergent in the
presence or imminent danger of neurological deficit.
In specific cases, transoral biopsy is the simplest way
to obtain samples for biopsy (tumors, infection).
All available standard radiological workouts are
always performed. MRI is mandatory and CTA can
give an important information regarding the course of
vertebral and carotid arteries in selected cases.
Careful inspection of the mouth, extent of orifice
opening, and mobility of cervical spine is always examined before transoral surgery. Specific investigations can
be performed, such as simulation of reachable areas
under fluoroscopy in an awake patient. This is performed
with a blunt metal rod after the dorsal part of the tongue
and oropharynx is locally anesthetized. Although this
procedure can be uncomfortable for the patient, it is the
most objective and valuable way of estimating the
achievable extension of the approach in a specific patient
(Fig. 4.6). Under fluoroscopy, possible asymptomatic
hyperextension of UCS can also be tested preoperatively.
We find this method safer and more reliable than complicated calculations. IOM is almost always a necessity in
UCS surgery; ventral aspect of the medulla lies close to
the surgical field and MEPs are therefore more useful
than SSEPs. Electrophysiology gives the surgeon vital
information and confidence in certain situations. It is
also useful to control the effect of anterior spinal decompression and it allows a safe rotation of the patient prior
to posterior fusion. Airways are secured via orotracheal
tube. Tracheotomy is reserved for complex surgeries or
cases with high probability of prolonged respirator-
Fig. 4.6 Preoperative fluoroscopical testing of transorally reach-
able areas in awake patient
assisted ventilation postoperatively. We use a local surface application of naphazoline in order to achieve
vasoconstriction in nasal and oral mucosa, and local cortisone ointment to prevent swelling of lips. The antibiotic prophylaxis according to hospital’s policy is
administered before anesthesia. The transoral intubation
with reinforced tube is performed with or without
fiberoptical guidance. In patients with marked compression and/or neurologic deficit, awake intubation is preferred. Although it is better tolerated in awake patients,
we do not use nasotracheal intubation as the tube would
cross the surgical field and possibly limit lateral extension of the field, as well as increase the risk of infection.
The head is positioned onto “horseshoe” pads for
cases of simple decompression. Mayfield clamp is
always used when stabilization is planned in the same
session (Fig. 4.7). The positioning of the head is very
important. Slight extension of the cervical spine may
enhance the surgical access to the clival edge. Possible
craniocaudal extension of TO approach is tested again
using a metal rod and a fluoroscope prior to fixation
in the final position. Fluoroscopical visibility of anterior atlantal tubercle and other important anatomical
landmarks have to be checked. Simple laryngoscope
can be helpful when disinfecting the oral cavity thoroughly. The incisives are protected with silicon rubber half-tube. In patients with irregular dentition, it
might be difficult to anchor the distraction frame cranially. Polymethacrylate template of upper jaw made
preoperatively can make the maxillary anchorage
easier. After the first disinfection and circumferential