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Surgical Approach to the Distal Extracranial Internal Carotid Artery at the Base of the Skull
 

Surgical Approach to the Distal Extracranial Internal Carotid Artery at the Base of the Skull

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    Surgical Approach to the Distal Extracranial Internal Carotid Artery at the Base of the Skull Surgical Approach to the Distal Extracranial Internal Carotid Artery at the Base of the Skull Document Transcript

    • 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. Summary 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.
    • Introduction 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 externum.
    • Technique 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 carotid artery. 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. References: 1. De Palma R. G. Surgery, Gynecology, Obstetrics, 1977, vol. 144, N 2, p. 249-250. 2. Ernst C. B. Surgical Rounds, 1985, vol. 8, N 1, p. 21-29. 3. Fisher D. F., Clagett G. P. Journal of Vascular Surgery, 1984, vol. 1, N 8, p. 727-731. 4. Imparato A. M., Bracco A., Kim G., Bergman L. Stroke, 1972, vol. 3, N 5, p. 576-578. 5. Vannix R. S., Joergenson E. J., Carter R. American Journal of Surgery, 1977, vol. 134, N 1, p.82-89. 6. Wylie E. J., Stoney R. J., Ehrenfeld W. K. Manual of Vascular Surgery. New York, 1986.