Surgical Approach to the Distal Extracranial Internal Carotid Artery at the Base of the Skull
Khirurgia ( Moscow ) , 1989, N. 3, p. 35-40
Хирургический доступ к дистальной экстракраниальной
части внутренней сонной артерии у основания черепа
( The original paper is published in Russian language in the journal „ Khirurgia, Moscow,
1989 ). This is the translation into English language, because worldwide used language is
English and it will be more convenient for readers to read it in English. If one wants to read
the original paper, he can read it in the journal „ Хирургия „ , Москва, 1989 N 3 p. 35-40 ).
Surgical approach to the distal extracranial part of the internal
carotid artery at the base of the skull
Prof., Dr. Scs. Povilas Pauliukas
Vascular surgeons, operating internal carotid artery lesions sometimes have difficulties
with exposure of the most distal portion of the internal carotid artery. If one wants to
operate safely internal carotid artery lesions, he has to know how to expose the internal
carotid artery at the base of the skull, foramen caroticum externum. Such situations usually
emerge while operating internal carotid artery aneurysms, high extending atherosclerotic
plaques, degenerated, with intimal dissection high loops of internal carotid arteries and
traumatic its lesions at the base of the skull. In addition, this approach is very useful while
operating the tumors at the base of the skull: carotid body tumors, neurinomas of vagal
nerve and other cervical retropharyngeal nerves. This approach enables to perform all
above-named operations in parapharyngeal region safely, preserving all nerves, pharyngeal
plexus, all muscles, involved in swallowing and does not require such drastic surgical
maneuvers, like resection of the mandible, its luxation, resection of the mastoid process.
Despite that fact, that all these maneuvers facilitate exposure of the internal carotid artery,
however they do not allow to preserve the nerves and muscles involved in swallowing
process. That is, why patients after such procedures have the swallowing disturbances, often
seriously disabling. Author of this paper from 1983 year uses only his original, described
here, approach to the base of the skull, independently what pathology is operated in this
area, and never had serious swallowing disturbances after the operations due to injury to
the nervous or muscular structures of the pharynx.
I believe that surgical technique for exposure of the most distal extracranial part of
the internal carotid artery at the base of the skull, developed by me, will be useful for
vascular surgeons, neurosurgeons and other surgeons, operating in this area.
The operative technique of surgical approach to the distal extracranial part of the
internal carotid artery at the base of the skull is described. The method allows to
perform reconstructive operations on the distal part of the internal carotid artery with
preservation of the intactness and function of the muscles and nerves of the pharynx.
Surgical approach to the distal extracranial part of the internal carotid artery is very
complicated and difficult, because this part of the internal carotid artery is covered from the
front by the mandible branch, above it is a base of the skull, from behind it is obscured by the
vertebral column and the occipital bone. In the medial aspect of it is situated the pharynx.
From the lateral view, there is a narrow gap between the mastoid process and the mandible
branch. However, in this narrow gap between osseous structures internal carotid artery is
covered from the lateral aspect by the parotid gland, facial nerve, glossopharyngeal nerve,
hypoglossal nerve, pharyngeal nervous plexus, which supplies the innervation to the pharynx
and to its muscles, styloid process and several muscles, fulfilling the act of swallowing. Dorsal
to the internal carotid artery passes the vagal nerve and its branch – superior laryngeal nerve,
sympathetic trunk and its superior ganglion of the neck. Close to the base of the skull the
internal carotid artery and internal jugular vein is crossed from the lateral aspect by the
accessory nerve. Lateral to the internal carotid artery in the neck and at the base of the skull
passes the internal jugular vein.
Surgeon faces two challenges together: one - to reach and expose the internal carotid
artery at the base of the skull and to create the necessary space, allowing to perform the
needed operation, second – to preserve muscles, fulfilling the act of swallowing and nerves,
innervating them, which are tightly surrounding the internal carotid artery.
The need to expose the internal carotid artery high, at the base of the skull, emerge in
cases of its traumatic lesions at the base of the skull, aneurysms, high extending, long
atherosclerotic plaques while performing endarterectomy procedure, in cases of degenerated,
symptomatic loops of internal carotid arteries with intimal dissection, partial thrombosis and
embolisation into cerebral arteries and in cases of complications while operating the proximal
part of internal carotid artery ( for example – intimal dissection, intimal flap existence after
internal carotid shunt was used in carotid artery, when there is a need to interpose an
autovenous shunt into the position of internal carotid artery etc.).
Majority of vascular surgeons, operating carotid arteries, limit their surgical actions at
the proximal part of the internal carotid artery, which is easy exposed. However, in case of
complications, which necessitate reconstructing internal carotid artery at the base of the skull,
they encounter big problems, complications and even danger for patient’s health and life if
they do not know how to expose the distal part of the extracranial internal carotid artery.
That’s, why every surgeon, operating on internal carotid arteries, must know and be skilled
how to approach the internal carotid artery at the base of the skull.
Historically, vascular surgeons began to ascend along internal carotid artery gradually.
A. Imparato proposed to mobilize the hypoglossal nerve [ 4 ]. R. De Palma proposed to
divide digastric and stylohyoid muscles, ligate the occipital artery, which crosses the internal
carotid artery laterally. Using these maneuvers one can expose internal carotid artery
approximately to its midpoint, because higher internal carotid artery is covered from the
lateral aspect by styloid process, muscles and ligaments, attached to it, which are playing an
important role in the swallowing act. Pharyngeal nervous plexus closely wreathe the internal
carotid artery at this level. Exposing the internal carotid artery higher than this point usually is
associated with swallowing and phonation difficulties [ 5 ].
There were proposals to resect the branch of the mandible in order to facilitate the
exposure of the distal part of the internal carotid artery [ 2, 6 ], ( Fig.1 A, B; Fig. 2 ).
Figure 1 A Figure 1 B
( Vertical osteotomy of the mandible branch )
With the same intention other authors proposed to subluxate the joint of the mandible and
retract the mandible to the front and down. [2, 3 ] ( Fig. 3 ), in order to widen the gap
between the mandible and spinal column. Both these methods do not solve the main problem
– how to preserve the muscles, participating in the act of swallowing and phonation and
intactness of their innervation and other important nerves of this region.
Figure 2 Figure 3
( Horizontal osteotomy of the mandible branch ) ( Subluxation of the mandible )
Author developed technique for exposure of the distal internal carotid artery at the base
of the skull, which preserves all muscles and nerves in this area, normal swallowing and
phonation function and creates adequate space for performing reconstructive operations on the
most distal part of the extracranial internal carotid artery up to the foramen caroticum
Patient is placed in the supine position with head slightly reclined and rotated to the opposite
side. Skin incision is made along and in the front of sternocleidomastoid muscle from mastoid
process until the middle of the neck. ( Fig. 4 ). Subcutaneous tissue and platysma are
transsected. External jugular vein is divided between two ligatures. N.. auricularis magnus is
transsected ( it has only sensory fibers and the numbness of the ear clears in several months ).
Wound is widened with self-retaining retractor. Sternocleidomastoid muscle can be divided
one centimeter below mastoid process. This maneuver adds an extra space for manipulations
with the most distal part of the internal carotid artery at the foramen caroticum externum. It is
sutured during wound closure.
Figure 4. Skin incision Figure 5. Neck region, which will be
analyzed in detail in the text. Parotid
gland is not depicted for clarity reason.
One must be carefull cutting the sternocleidomastoid muscle not to cut the accessory nerve,
which crosses obliquely the internal surface of the sternocleidomastoid muscle. The facial
nerve is also close to mastoid process as it emerges from the foramen stylomastoideum and
turns toward the parotid gland. One must have it in mind while retracting the parotid gland,
and retract it delicately, otherwise facial nerve postoperative palsy may occur due to its
hyperextension. Carotid artery bifurcation is exposed and common, internal and external
carotid arteries are encircled with the tapes. Important anatomical structures and their
topographical relations in the wound are depicted in Fig. 6. Sympathetic trunk and internal
jugular vein are not depicted, because they are situated on the lateral-dorsal aspect of the
wound and there is no need to dissect them.
Dissection of the internal jugular vein at the base of the skull, especially its dorsal surface,
damages the lymphatic channels, draining the lymph from the nasopharynx. This causes
intumescense of the pharynx and tonsils to the degree that intubation of the patient sometimes
is needeed to peserve his breathing and to prevent asphyxia. Furthermore, there is a danger to
damage accessory nerve, which is closely adhered to internal jugular vein on the frontal
surface of vein. Finally, there is unnessesary and unwarranted dissection, which do not
enhance the space or ability to work with the distal portion of the internal carotid artery.
The tendon of the digastric muscle is divided between two retaining sutures and both its
ends are retracted to the opposite sides. ( Fig. 7 ). One must be very carefull not to damage the
hypoglossal nerve. It must be indentified in the wound as soon, as possible and encircled with
the tape. Then, internal carotid artery is dissected upwards, carefully ligating small veins,
crossing the internal carotid artery in front of it. These veins are very delicate and should be
ligated after encircling them with ligature using microdissector and divided between two
ligatures, because hemostats usually tear these tiny veins and troublesome bleeding may
occur. In case of bleeding from these venules one must be very carefull not to damage
pharyngeal nervous plexus, hypoglossal or pharyngeal nerves, because damage especially of
pharyngeal plexus will cause dysphagia, sometimes disabling. Therefore, dissection and all
surgical actions in this area should be very precise and carefull.
Figure 6 Figure 7
In Figures 6 - 15 the same numbers marks all important anatomic structures:
1 – venter posterior m.digastrici; 2 – m. stylohyoideus; 3 – a. sternocleidomastoidea; 4 – a.
occipitalis; 5 – plexus pharyngeus; 6 – n. hypoglossus; 7 – n. glossopharyngeus; 8 - proc.
styloideus; 9 – n. facialis; 10 – n. vagus; 11 – n. laryngeus superior; 12 – ramus marginalis
n. facialis; 13 – m.sternocleidomastoideus; 14 – a. carotis interna; 15 – a. carotis externa.
Other explanations are in the text.
Sternocleidomastoid artery, which branches from the external carotid artery or
sometimes – occipital artery and sternocleidomastoid vein, crosses and fixes the hypoglossal
nerve on the cranial aspect ( Fig. 6 ). Therefore, hypoglossal nerve can be retracted upwards
without its hyperextension and damage only if these small vessels are ligated and divided.
Damage of this nerve causes dysarthria, deviation of the tongue, fibrillation and atrophy of the
muscles of the affected side. A. Imparato was the first, who proposed this maneuver [ 4 ].
After ligation of sternocleidomastoid artery and vein, the hypoglossal nerve can be easily
displaced far upwards, so, that internal carotid artery can be exposed quite high ( Fig. 7 ), but
not to the base of the skull. Such technique for exposure of the internal carotid artery
personally I use always, even in cases of typical endarterectomy of the internal carotid artery,
because this technique allows safely and comfortably remove atherosclerotic plaque, even if it
extends high distally. Furthermore, such adequate exposure of the internal carotid artery
strongly facilitates the use of the internal shunt, when blood flow to the corresponding brain
hemisphere while clamping internal carotid artery is insufficient. Majority of vascular
surgeons, operating internal carotid arteries, use such technique of exposure of the internal
Further maneuvers are required only if there is a need to expose and to reconstruct the
internal carotid artery at the base of the skull.
The tendon of the slylohyoid muscle is divided between two retaining sutures and
retracted into the opposite sides. ( Fig. 7 ). Digastric and stylohyoid muscles must be divided
at the tendon portion in order not to damage the innervation of these muscles and to preserve
their normal function postoperatively. Facial nerve small branches supply the motor
innervation to these muscles. Kocher-Langenbeck or US Army type blunt retractor is used to
delicately retract parotid gland upwards. Forcefully retracting parotid gland causes
hyperextension of the facial nerve and postoperative paralysis of the muscles on the operated
side of the face. Hypoglossal, glossopharyngeal nerves and fine mesh of the pharyngeal
nervous plexus between these two nerves are clearly seen after this maneuver. ( Fig. 7 ).
Pharyngeal plexus is composed of the sensory fibers from glossopharyngeal nerve, motor
fibers from vagal nerve, sympathetic fibers from the sympathetic trunk and parasympathetic
fibers from the vagal nerve. It is very important to work very delicately with pharyngeal
nervous plexus and preserve its fibers from any trauma, especially from cutting any fiber,
because damage to any fiber ( sensory or motor ) will cause sensory or motor derangement of
the pharynx to the degree that patient will be unable to swallow even water postoperatively.
Pharyngeal plexus is separated very delicately bluntly into two parts by displacing
nervous fibers along their course in the middle of the plexus upwards and downwards, thus
making a window in the middle of the plexus. Then, the upper part of the pharyngeal plexus
together with the glossopharyngeal nerve and the lower part of it together with the
hypoglossal nerve are encircled with the tapes and delicately retracted into opposite sides in
order to enlarge the window, through which is mobilized that part of the internal carotid
artery, which is situated behind the pharyngeal plexus ( Fig.8 ). Then, the upper part of the
pharyngeal plexus together with glossopharyngeal nerve is retracted downwards ( Fig. 9. )
whereupon styloid process is clearly seen. It can be of different thickness and length:
sometimes - only short, thin, cartilaginous, sometimes – osseous, very thick and long. The
middle part of the styloid process is denuded from tiny muscle fibers bluntly using two fingers
only in very short distance, just to enable the surgeon to cut the styloid process with fine
Liston type cutting forceps. The dissector should be used to denude the styloid process in case
when it is not enough the space for fingers. The surgeon should clearly see the jaws of forceps
and the anatomic structures close to the styloid process while cutting the styloid process. The
base of the styloid process should be left intact in order not to strip attachment of the
stylohyoid muscle and to avoid damage to the trunk of the facial and glossopharyngeal nerves,
which are very close to the base of the styloid process. The attachment of the stylohyoid
muscle to the base of styloid process is preserved in order to preserve its normal function after
the operation ( both ends of its tendon portion are sutured at the end of operation ). Distal part
of the styloid process is also left intact, preserving the attaching to it stylopharyngeal,
styloglossal muscles and stylomandibular ligament. The place, where the styloid process
should be cut is depicted by dotted line in Fig. 9. The styloid process together with the
muscles, attaching to it, is retracted to the medial part of the wound ( Fig. 10 ).
Figure 8 Figure 9
Figure 10 Figure 11
The most distal part of the internal carotid artery up to the foramen caroticum externum
now is accessible for exposure after cutting the styloid process. The internal carotid artery is
encircled with the tape and gently dissected from the adherent tissue up to the foramen
caroticum externum, or to the level, which is needed for reconstruction of the internal carotid
artery. Thereafter, the operation is performed for which this high approach to the internal
carotid artery is used. The most difficult cases are traumatic lesions of the distal extracranial
internal carotid artery, aneurysms of the internal carotid artery, big carotid body tumors
and other tumors of the parapharyngeal region of the neck.
In this paper as an example, I shall analyze the technique of reconstruction of internal
carotid artery in case of high loop, which is situated close to the foramen caroticum externum.
Usually loops of internal carotid artery need to be operated when they are symptomatic,
degenerated, sometimes have aneurysmatic dilatations of the artery, with intimal spontaneous
dissection and partial thrombosis and embolization into the cerebral arteries, or if they have
tight septal symptomatic stenosis due to the one or two kinks at the poles of the loop.
If the problem is kinking of the internal carotid artery and its wall is not degenerated,
the internal carotid artery is mobilized to the normal internal carotid artery above the loop or
as high, as is needed. Then the internal carotid artery is pulled down to the bifurcation and cut
obliquely from the bifurcation. The length excess of internal carotid artery is resected and it is
reimplanted back into incised down, widened orifice of common carotid artery ( Fig. 11 ).
In case, the internal carotid artery is degenerated, with arterial wall deterioration,
intimal dissection, aneurysmal transformation, or if the poles of the loop can not be
straightened due to arterial wall degeneration, such loops must be entirely resected with “ end
to end “ anastomosis of the ends of residual intact internal carotid artery. In such cases the
internal carotid artery is mobilized from the bifurcation up to the foramen caroticum externum
( if the loop is situated high at the base of the skull ) or as high, as needed. Then the internal
carotid artery is cut transversely just below the loop trough the window made in the
pharyngeal plexus ( Fig.12 ).
Figure 12 Figure 13
Both ends of internal carotid artery are pulled from behind the pharyngeal plexus, hypoglossal
and glossopharyngeal nerves and put in front of them. So, the entire internal carotid artery is
in front of all nervous structures and is very easy to work with it. The entire loop is resected,
leaving both internal carotid artery ends with intact, normal wall ( Fig. 13 ). The ends of
internal carotid artery are approximated and sutured in “ end to end “ fashion ( Fig. 14 ) .
After completing the anastomosis, entire internal carotid artery is located in front of all
nervous structures ( Fig. 15 ).
Figure 14 Figure 15
Then the styloid process is sutured to the digastric muscle attaching part on the base of
the styloid process in transverse fashion by “ U “ type non resorbable suture ( Fig. 11 ), thus
restoring the normal function of the muscles so important for swallowing act, attached to the
styloid process. In the same manner, styloid process together with its muscles is attached to
the base of digastric muscle in case of internal carotid artery loop resection and “ end to end “
anastomosis and positioning of sutured internal carotid artery in front of nervous structures as
well. Only in such way it is possible to preserve the integrity and normal function of these tiny
muscles ( stylopharyngeal, styloglossal ) because if one cuts them transversely, they contract,
they are very tiny and tear very easy, so it is impossible to reattach their contracted ends back
by suture. Therefore, it is an imperative to preserve these muscles intact and attached to the
styloid process, because in such way, their innervation is preserved and they are reliably fixed
to the skull together with the styloid process.
Then with “ U “ type sutures are reattached the tendons of stylohyoid and digastric
muscles. If the sternocleidomastoid muscle was cut transversely just below mastoid process, it
is reattached by several “ U “ type sutures. The wound is drained and closed in layers.
I use this technique for exposure of the distal extracranial part of the internal carotid
artery for many years, from 1983 year. This technique I use and for resection of carotid body
tumors, other tumors of the parapharyngeal region. I used this technique in more than 100
patients. I never had any serious complications. One patient had slight facial hemiparesis due
to hyperextension of the facial nerve trunk by assistant, which cleared in 3 months. Two
patients had impeded swallowing due to the particular cause: muscles participating in the
swallowing act were hyperextended by huge tumor: vagal nerve neurilemoma in one case and
huge internal carotid artery aneurysm in the second case. After the removal of tumor and
aneurysm, muscles were intact, however hyperextended and too long and weak on the
operated side for enabling patient to swallow normally. The swallowing act recovered in both
patients in 6 months period to normal due to increase of strength and shortening of muscles,
participating in swallowing act.
Several other patients had just very slight worsening of swallowing, which cleared in several
days or weeks.
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