Selected techniques
Enhanced Surgical Exposure for the High Extracranial Internal Carotid Artery Steven Richard Nelson, DDS, Sterling Robert Schow, DMD, Stephen Milton Stein, DDS, Lance Alexander Read, DDS, Clement McCarty Talkington, MD, Dallas, Texas
The need for enhanced surgical exposure for the high extracranial (Zone III) internal carotid artery is not uncommon. In certain circumstances, the posterior border and angle of the mandible may interfere with access to the distal internal carotid artery (ICA). The use of modified mandibular osteotomies has provided vascular surgeons in our institution with improved exposure of the ICA in selected cases. The intraoral sagittal split and extraoral vertical ramus osteotomies of the mandible allow manipulation of the posterior border and angle of the mandible with low morbidity and minimal postoperative complications. These procedures can be performed for both dentate and edentulous patients without the need for intermaxillary fixation. This paper introduces these modifications and discusses the benefits over previously described methods of mandibular manipulation. (Ann Vasc Surg 1992;6:000-000). KEY WORDS: artery.
Carotid endarterectomy; mandibular osteotomy; internal carotid
Surgical access for most lesions encountered during carotid endarterectomy can be obtained through a standard approach with hyperextension and contralateral rotational positioning of the patient's head. However, in cases of high bifurcation, distal extension of carotid plaques, or in blunt or penetrating trauma, additional exposure of the carotid artery may be necessary to obtain distal control. Numerous and innovative techniques to enhance exposure have been described in the vascular, neurosurgical, and otolaryngological literature, each with their From the Department of Oral and Maxillofacial Surgery, and the Department of Vascular Surgery, Baylor University Medical Center, and the Baylor College of Dentistry, Dallas, Texas. Reprint requests: Sterling R. Schow, DMD, Department of Oral and Maxiltofacial Surgery, Baytor College of Dentistry, 3302 Gaston Avenue, Dallas, Texas 75246. 467
own potential morbidity and shortcomings. These include division of the stylohyoid and digastric muscles, mandibular subluxation, mastoidectomy, removal of the styloid process, mandibular osteotomies, and resection of the temporomandibular joint articulation [1-151. In this paper, we present modifications of two mandibular osteotomies that are commonly performed by oral and maxillofacial surgeons to correct maxillofacial deformities [16]. These modified procedures can be utilized by the vascular surgeon to obtain direct exposure for distal control of the internal carotid artery in difficult access cases.
TECHNIQUES Prior to performing either of the following techniques, a preoperative panoramic radiograph is ob-
E N H A N C E D SURGICAL EXPOSURE FOR THE EXTRACRANIAL ICA
468
ANNALS OF VASCULAR SURGERY
All A.
B.
Fig. 1. (A-E) Modified sagittal split osteotomy technique is depicted above. Please refer to text for detailed explanation in sequence.
tained, if possible. This assists in locating the position of the mandibular foramen and allows the surgeons to identify bony pathology of the mandible which could be addressed, if indicated, prior to the procedure. Intraoral sagittal split osteotomy
This technique is performed intraorally, avoiding an extension or modification of the external incision used for exposure of the carotid artery as well as contamination of the surgical site. The oral and maxillofacial surgery team performs this osteotomy prior to beginning the carotid approach. A transorat incision is made to allow access to the mandibular ramus and body. The ramus of the mandible is then divided by creating a horizontal osteotomy on the medial aspect of the ramus above the mandibular foramen and a vertical osteotomy on the lateral aspect of the mandible in the molar tooth region. These osteotomies are connected by an anterior ramus osteotomy (Figs. la,b), At this point, a four hole bone plate is contoured
Fig. 2. Figures illustrate access gained by sagittal split osteotomy, With mouth in a closed position, posterior ramus can prohibit adequate access to ICA (A). After completion of osteotomy, ramus can be rotated anteriorly and superiorly with minimal stress placed on temporomandibular joint providing improved access to ICA (B).
to fit passively near the inferior border of the mandible with two holes on either side of the vertical bone cut (Fig. lb), A percutaneous trocar is introduced into the surgical site through a 5 mm stab incision in the cheek adjacent to the lateral osteotomy site on the mandible. Monocortical bone screws are placed through the trocar cannula to secure the bone plate. The screws and bone plate are removed and saved and the mandible is then carefully separated into proximal and distal segments (Fig. lc). This allows the mandibular ramus to be rotated superiorly and anteriorly, improving surgical access to the carotid artery (Fig. 2). At this point, the oral cavity can be isolated from the carotid surgical site with a steridrape and the vascular surgery team can proceed. It is important to note that communication with the internal carotid artery (ICA) surgical site is avoided. This is because
VOLt:ME 6 NO 5 - 1992
E N H A N C E D S U R G I C A L E X P O S U R E FOR THE E X T R A C R A N I A L ICA
minimal reflection of the tissues is required to perform the osteotomies. Reflection of tissues posteriorly is located only on the medial portion of the ramus, and most importantly, the mandibular periosteal sling remains intact throughout the procedure. At the completion of the vascular procedure, the proximal and distal segments of the mandible are anatomically repositioned by reapplying the bone plate and placing the screws from the percutaneous approach (Fig. Id). Additional stability is obtained by placing two or three bicortical screws at the external oblique ridge (Fig. le). The surgical site is then irrigated with copious amounts of sterile saline and closed with 3-0 chromic gut suture. We have used this procedure successfully in the treatment of 11 patients.
i
469
A.
Extraoral vertical ramus osteotomy
This technique can be utilized in cases where the need for increased access is questionable preoperatively. This procedure is performed after the vascular surgeons have made their initial approach to the carotid artery. Depending on the access to the mandible, a modification of the incision may be necessary by adding a 5 cm curvilinear anterior extension 2 cm below the inferior border of the mandible from the standard incision. Care is taken to avoid injury to the marginal mandibular branch of the facial nerve. The pterygomasseteric muscular sling is incised at the inferior border of the mandibular angle, and the lateral aspect of the ramus is exposed. The proposed osteotomy site is outlined from the sigmoid notch area to the angle of the mandible posterior to the position of the mandibular foramen. A T-shaped bone plate is contoured to fit passively over the proposed osteotomy and secured with bicortical screws (Fig. 3a). The bone plate is removed and the ramus is sectioned, allowing the proximal segment to be rotated laterally and anteriorly to improve surgical access (Figs. 3b, 3c). At the completion of the vascular surgery, the segments are anatomically repositioned and stabilized by reapplying the bone plate (Fig. 3d). Closure is obtained in standard fashion. This technique has been utilized on five occasions with excellent results.
DISCUSSION In certain circumstances, the need for enhanced surgical exposure of the high extracraniat ICA is required. According to Thompson [7], a high plaque is one located above the level of the third cervical vertebra. Hans and associates [6], have arbitrarily
C.
:
D.
Fig. 3. Extraoral vertical ramus osteotomy is illustrated. Please refer to text for detailed explanation in sequence.
divided the cervical ICA into three zones: Zone I extends from the carotid bifurcation to the superior margin of the third cervical vertebra (C-3); Zone II extends from the superior margin of C-3 to the inferior margin of C-l; and Zone III extends from the inferior margin of C-1 to the base of the skull. Utilizing these divisions when evaluating preoperative or posttraumatic arteriograms of the ICA can help determine the need for enhanced surgical exposure. The Zones of Hans should not be confused with the anatomical zone-based management of penetrating neck trauma used to evaluate neck wounds.
470
E N H A N C E D S U R G I C A L E X P O S U R E FOR THE E X T R A C R A N I A L ICA
a
ANNALS OF VASCULAR SURGERY
b
d Fig. 4. (A,B) Radiographic case illustration is presented. Arteriogram was obtained in 78-year-old white man with symptoms of transient ischemic attack. Stenosis of left internal carotid artery was noted in Zone III. (C) Preoperative panorex for planning mandibular ramus sagittal osteotomy to improve surgical access. (D) Postoperative panorex.
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471
Many techniques have been developed over the transsected vertically anterior to the medial forayears to provide enhanced access to high lesions of men and horizontally across the mandibular ramus, the ICA. Fry and Fry [2], Thompson [7], Callow [8], superior to the mandibular foramen. This allowed Fischer and colleagues [I 3], and Dossa and cowork- adequate manipulation of the free segment for ICA ers [14], have all advocated forward subluxation of exposure. Restoration was accomplished with a the temporomandibular joint. Though this appears bone plate to reapproximate the parasymphysis to be a reasonable technique, it possesses many osteotomy and a Kirshner wire for the ramus osinherent problems. The amount of forward sublux- teotomy. The likely complications of this procedure ation is limited by the multiple ligamantous attach- include mucosal laceration with oral contamination ments to the condyle and mandible, and forward and injury to the marginal mandibular branch of the mobility of the mandible averages only 9 mm [17]. facial nerve. Wylie and Ehrenfeld [10], developed a subperiAdditionally, subluxation of the temporomandibular joint for an extended period of time places the osteal osteotomy with lateral rotation of the proxipatient at risk for developing joint symptomatology mal segment upward, over the temporomandibular and, possibly, internal derangement with intraartic- joint, with forward retraction of the anterior segular disc displacement [18]. Mattox [15] recom- ment. This approach has also been utilized by mends deliberate dislocation of the temporoman- Welsh and associates [11,12]. Additionally, the stydibular joint. This has the same limitations as loid process was removed and the digastric muscle subluxation of the temporomandibular joint and was divided. These authors described a wire fixafurthers the potential for intraarticular pathology to tion technique of the segments and did not allow develop. The performance and maintenance of ei- their patients to chew for at least three weeks. With ther of these maneuvers in the edentulous patient is lateral rotation of the proximal segment, the patient is at increased risk of developing both temporomandifficult. Many authors have promoted division or resec- dibular joint dysfunction and facial nerve palsey. tion of various muscular attachments with and This stabilization technique did not assure anatomic without removal of the mastoid process. DePalma mandibular repositioning, nor did it allow the pa[11 described dividing the stylohyoid and digastric tient to resume immediate postoperative mandibumuscles as weld as the ansa hypoglossi. Purdue and lar function. The techniques we describe provide a new and associates [3], reported a technique utilizing preand postauricular incisions allowing dissection of perhaps superior option for enhanced exposure of the parotid gland anteriorly, resection of the digas- the high ICA lesion. These osteotomies allow extric muscle from the mastoid process, avulsion of cellent manipulation of the posterior ramus and the styloid process with resection of the stylohyoid angle of the mandible with minimal stress to the muscle, and radical mastoidectomy. Deficiencies temporomandibular joint, parotid gland, and facial with these techniques include compromised Zone nerve. They can be performed on edentulous or III access, decreased mandibular range of motion dentate patients without developing intraoral comfrom resection of the digastric and stylohyoid mus- munications. The use of rigid fixation with cles, which we have observed in our patients, and preadapted bone plates and screws provides anatomic reapproximation and allows the patient to increased potential for nerve injury. A more radical approach has been described by function normally in the immediate postoperative Fisch and colleagues [9]. He recommended a radi- period. The stability provided by the bone plate cal mastoidectomy with obliteration of the middle eliminates the need for maxillomandibular fixation ear and resection of the mandibular condyle. The for anatomic reapproximation. Most patients are postsurgical functional problems resulting from this able to tolerate a soft diet within one week [16]. The preadaptation of the bone plate prior to completion technique are obvious. Various osteotomies to displace the angle of the of the osteotomy is a simple modification of procemandible into a position providing better access to dures performed routinely by oral and maxillofacial Zones II and III have been attempted. Batsdorf and surgeons across the nation. It assures anatomic Gregorius [4] used a horizontal osteotomy of the repositioning and fragment stabilization sufficient ramus superior to the mandibular foramen and a for mandibular function in the immediate postopervertical oblique osteotomy in the third molar re- ative period. Complications of these procedures are rare but, gion, anterior to the masseter attachment. This allowed lateral manipulation of the angle and pos- as with any mandibular osteotomy, include paresterior border of the mandible. The segment was thesia of the inferior alveolar nerve, inappropriate later wired back into position. Balagura and co- separation of the proximal and distal segments workers [5] modified the osteotomies of Batsdorf (which can be rectified with further modified osteotand Gregorius for use in edentulous patients. A omies), infection and bony nonunion [14,161. Ideally, the sagittal split osteotomy should be modified incision allowed access to the parasymphysis region of the mandible. The mandible was utilized. It provides a larger bone contact area for
472
ENHANCED SURGICAL EXPOSURE FOR THE EXTRACRANIAL ICA
healing and allows additional fixation, promoting faster healing and recovery. The sagittal split osteotomy is done prior to exposing the ICA to prevent oral contamination. Mandibular stabilization is accomplished after the neck incision is closed and protected. Careful preoperative evaluation of the patient and determination of the level of the lesion in the ICA is paramount to the decision to begin the operation with a sagittal osteotomy. Nevertheless, if the preoperative evaluation is ambiguous, the ICA dissection can be performed first. If improved access is deemed necessary intraoperatively, the extraoral vertical ramus osteotomy is accomplished through the ICA incision.
CONCLUSIONS This paper introduces modifications of two common surgical procedures performed routinely by oral and maxillofacial surgeons to correct facial deformities. The vascular surgeon can utilize these well established procedures to help obtain direct visualization of the high extracranial (Zone III) internal carotid artery.
REFERENCES 1. DEPALMA RG. Optimal exposure of the internal carotid artery for endarterectomy. Surg Gynecol Obstet 1977;144: 24%250. 2. FRY RE, FRY WJ. Extracranial carotid artery injuries. Surgery 1980;88:581-586. 3. PURDUE GF, PELLIGRINI RV, ARENA S. Aneurysms of the high internal carotid artery: a new approach, Surgery t 981 ;89:268-270. 4. BATZDORF U, GREGORIUS FK. Surgical exposure of the high cervical carotid artery: experimental study and review. Neurosurgery 1983;13:657--661.
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5. BALAGURA S, CARTER JB, ANDGOSSETT DL. Surgical approach to the high subcranial internal carotid artery. Neurosurgery 1985;16:402-405. 6. HANS SS, SHAH S, HANS B. Carotid endarterectomy for high plaques. Am J Surg 1989;157:431-434. 7. THOMPSON JE. Carotid endarterectomy for high plaques (editorial comment). Am J Surg 1989;157:434--435. 8. CALLOW AD. Cerebrovascular insufficiency. In: HAMOVICI H, CALLOW AD, ERNST CB, DEPALMA RG, HOL° LIER LH (eds). Haimovici's Vascular Surgery. Norwalk, CT: Appleton and Lange, 1989, pp 72%730. 9. FISCH UP, OLDRING DJ, SENNING A. Surgical therapy of internal artery lesions at the skull base and temporal bone. Otolaryngol Head Neck Surg 1980;88:548-554. 10. WYLIE EJ, E H R E N F E L D WK. Extracranial Occlusive Cerebrovascular Disease: Diagnosis and Management. Philadelphia: W.B. Saunders, 1970. 11. WELSH P, PRADIER R, REPETTO R. High exposure of the carotid artery for difficult lesions. In: BERGAN J J, YAO JST (eds). Cerebrovascular Insufficiency. New York: Grune and Stratton, 1983, pp 433-447. 12. WELSH P, PRADIER R, REPETTO R. Fibromuscular dysplasia of the distal cervical internal carotid artery. J Cardiovasc Surg 1981;22:321-326. 13. FISCHER DF Jr, CLAGETT GP, PARKER JI, et al, Mandibular subluxation for high carotid exposure. J Vasc Surg 1984;1:727-733. 14. DOSSA C, SHEPARD AD, WOLFORD G, et al. Distal internal carotid exposure: a simplified technique for temporary mandibular subluxation. J Vasc Surg 1990;12:319-325. 15. MATTOX KL. Vascular trauma. In: HAIMOVICI H, CALLOW AD, ERNST CB, DEPALMA RG, HOLLIER LH (eds). tIaimovici's Vascular Surgery. Norwalk, CT: Appleton and Lange, 1989, pp 373. 16. TERRY BC, WHITE RP. Mandibular ramus surgery. In: PROFFIT WR, WHITE RP (eds). Surgical-Orthodontic Treatment. St. Louis: Mosby Year Book, 1991, pp 264-282. 17. RUGH JD, JOHNSON RW. Mandibular movements. In: MOHL ND, ZARB GA, CARLESON GE, RUGH JD (eds). A Textbook of Occlusion. Chicago: Quintessence Books, 1988, pp 131. 18. BELL WE. Temporomandibular Disorders: Classification, Diagnosis and Management. Chicago: Yearbook Medical Publishers Inc., 1986, pp 194-198,
Enhanced Surgical Exposure for the High Extracranial Internal Carotid Artery Steven Richard Nelson, DDS, Sterling Robert Schow, DMD, Stephen Milton Stein, DDS, Lance Alexander Read, DDS, Clement McCarty Talkington, MD, Dallas, Texas
The need for enhanced surgical exposure for the high extracranial (Zone III) internal carotid artery is not uncommon. In certain circumstances, the posterior border and angle of the mandible may interfere with access to the distal internal carotid artery (ICA). The use of modified mandibular osteotomies has provided vascular surgeons in our institution with improved exposure of the ICA in selected cases. The intraoral sagittal split and extraoral vertical ramus osteotomies of the mandible allow manipulation of the posterior border and angle of the mandible with low morbidity and minimal postoperative complications. These procedures can be performed for both dentate and edentulous patients without the need for intermaxillary fixation. This paper introduces these modifications and discusses the benefits over previously described methods of mandibular manipulation. (Ann Vasc Surg 1992;6:000-000). KEY WORDS: artery.
Carotid endarterectomy; mandibular osteotomy; internal carotid
Surgical access for most lesions encountered during carotid endarterectomy can be obtained through a standard approach with hyperextension and contralateral rotational positioning of the patient's head. However, in cases of high bifurcation, distal extension of carotid plaques, or in blunt or penetrating trauma, additional exposure of the carotid artery may be necessary to obtain distal control. Numerous and innovative techniques to enhance exposure have been described in the vascular, neurosurgical, and otolaryngological literature, each with their From the Department of Oral and Maxillofacial Surgery, and the Department of Vascular Surgery, Baylor University Medical Center, and the Baylor College of Dentistry, Dallas, Texas. Reprint requests: Sterling R. Schow, DMD, Department of Oral and Maxiltofacial Surgery, Baytor College of Dentistry, 3302 Gaston Avenue, Dallas, Texas 75246. 467
own potential morbidity and shortcomings. These include division of the stylohyoid and digastric muscles, mandibular subluxation, mastoidectomy, removal of the styloid process, mandibular osteotomies, and resection of the temporomandibular joint articulation [1-151. In this paper, we present modifications of two mandibular osteotomies that are commonly performed by oral and maxillofacial surgeons to correct maxillofacial deformities [16]. These modified procedures can be utilized by the vascular surgeon to obtain direct exposure for distal control of the internal carotid artery in difficult access cases.
TECHNIQUES Prior to performing either of the following techniques, a preoperative panoramic radiograph is ob-
E N H A N C E D SURGICAL EXPOSURE FOR THE EXTRACRANIAL ICA
468
ANNALS OF VASCULAR SURGERY
All A.
B.
Fig. 1. (A-E) Modified sagittal split osteotomy technique is depicted above. Please refer to text for detailed explanation in sequence.
tained, if possible. This assists in locating the position of the mandibular foramen and allows the surgeons to identify bony pathology of the mandible which could be addressed, if indicated, prior to the procedure. Intraoral sagittal split osteotomy
This technique is performed intraorally, avoiding an extension or modification of the external incision used for exposure of the carotid artery as well as contamination of the surgical site. The oral and maxillofacial surgery team performs this osteotomy prior to beginning the carotid approach. A transorat incision is made to allow access to the mandibular ramus and body. The ramus of the mandible is then divided by creating a horizontal osteotomy on the medial aspect of the ramus above the mandibular foramen and a vertical osteotomy on the lateral aspect of the mandible in the molar tooth region. These osteotomies are connected by an anterior ramus osteotomy (Figs. la,b), At this point, a four hole bone plate is contoured
Fig. 2. Figures illustrate access gained by sagittal split osteotomy, With mouth in a closed position, posterior ramus can prohibit adequate access to ICA (A). After completion of osteotomy, ramus can be rotated anteriorly and superiorly with minimal stress placed on temporomandibular joint providing improved access to ICA (B).
to fit passively near the inferior border of the mandible with two holes on either side of the vertical bone cut (Fig. lb), A percutaneous trocar is introduced into the surgical site through a 5 mm stab incision in the cheek adjacent to the lateral osteotomy site on the mandible. Monocortical bone screws are placed through the trocar cannula to secure the bone plate. The screws and bone plate are removed and saved and the mandible is then carefully separated into proximal and distal segments (Fig. lc). This allows the mandibular ramus to be rotated superiorly and anteriorly, improving surgical access to the carotid artery (Fig. 2). At this point, the oral cavity can be isolated from the carotid surgical site with a steridrape and the vascular surgery team can proceed. It is important to note that communication with the internal carotid artery (ICA) surgical site is avoided. This is because
VOLt:ME 6 NO 5 - 1992
E N H A N C E D S U R G I C A L E X P O S U R E FOR THE E X T R A C R A N I A L ICA
minimal reflection of the tissues is required to perform the osteotomies. Reflection of tissues posteriorly is located only on the medial portion of the ramus, and most importantly, the mandibular periosteal sling remains intact throughout the procedure. At the completion of the vascular procedure, the proximal and distal segments of the mandible are anatomically repositioned by reapplying the bone plate and placing the screws from the percutaneous approach (Fig. Id). Additional stability is obtained by placing two or three bicortical screws at the external oblique ridge (Fig. le). The surgical site is then irrigated with copious amounts of sterile saline and closed with 3-0 chromic gut suture. We have used this procedure successfully in the treatment of 11 patients.
i
469
A.
Extraoral vertical ramus osteotomy
This technique can be utilized in cases where the need for increased access is questionable preoperatively. This procedure is performed after the vascular surgeons have made their initial approach to the carotid artery. Depending on the access to the mandible, a modification of the incision may be necessary by adding a 5 cm curvilinear anterior extension 2 cm below the inferior border of the mandible from the standard incision. Care is taken to avoid injury to the marginal mandibular branch of the facial nerve. The pterygomasseteric muscular sling is incised at the inferior border of the mandibular angle, and the lateral aspect of the ramus is exposed. The proposed osteotomy site is outlined from the sigmoid notch area to the angle of the mandible posterior to the position of the mandibular foramen. A T-shaped bone plate is contoured to fit passively over the proposed osteotomy and secured with bicortical screws (Fig. 3a). The bone plate is removed and the ramus is sectioned, allowing the proximal segment to be rotated laterally and anteriorly to improve surgical access (Figs. 3b, 3c). At the completion of the vascular surgery, the segments are anatomically repositioned and stabilized by reapplying the bone plate (Fig. 3d). Closure is obtained in standard fashion. This technique has been utilized on five occasions with excellent results.
DISCUSSION In certain circumstances, the need for enhanced surgical exposure of the high extracraniat ICA is required. According to Thompson [7], a high plaque is one located above the level of the third cervical vertebra. Hans and associates [6], have arbitrarily
C.
:
D.
Fig. 3. Extraoral vertical ramus osteotomy is illustrated. Please refer to text for detailed explanation in sequence.
divided the cervical ICA into three zones: Zone I extends from the carotid bifurcation to the superior margin of the third cervical vertebra (C-3); Zone II extends from the superior margin of C-3 to the inferior margin of C-l; and Zone III extends from the inferior margin of C-1 to the base of the skull. Utilizing these divisions when evaluating preoperative or posttraumatic arteriograms of the ICA can help determine the need for enhanced surgical exposure. The Zones of Hans should not be confused with the anatomical zone-based management of penetrating neck trauma used to evaluate neck wounds.
470
E N H A N C E D S U R G I C A L E X P O S U R E FOR THE E X T R A C R A N I A L ICA
a
ANNALS OF VASCULAR SURGERY
b
d Fig. 4. (A,B) Radiographic case illustration is presented. Arteriogram was obtained in 78-year-old white man with symptoms of transient ischemic attack. Stenosis of left internal carotid artery was noted in Zone III. (C) Preoperative panorex for planning mandibular ramus sagittal osteotomy to improve surgical access. (D) Postoperative panorex.
VOLUME 6 N o 5 - 1992
E N t I A N C E D SURGICAL EXPOSURE FOR THE E X T R A C R A N I A L ICA
471
Many techniques have been developed over the transsected vertically anterior to the medial forayears to provide enhanced access to high lesions of men and horizontally across the mandibular ramus, the ICA. Fry and Fry [2], Thompson [7], Callow [8], superior to the mandibular foramen. This allowed Fischer and colleagues [I 3], and Dossa and cowork- adequate manipulation of the free segment for ICA ers [14], have all advocated forward subluxation of exposure. Restoration was accomplished with a the temporomandibular joint. Though this appears bone plate to reapproximate the parasymphysis to be a reasonable technique, it possesses many osteotomy and a Kirshner wire for the ramus osinherent problems. The amount of forward sublux- teotomy. The likely complications of this procedure ation is limited by the multiple ligamantous attach- include mucosal laceration with oral contamination ments to the condyle and mandible, and forward and injury to the marginal mandibular branch of the mobility of the mandible averages only 9 mm [17]. facial nerve. Wylie and Ehrenfeld [10], developed a subperiAdditionally, subluxation of the temporomandibular joint for an extended period of time places the osteal osteotomy with lateral rotation of the proxipatient at risk for developing joint symptomatology mal segment upward, over the temporomandibular and, possibly, internal derangement with intraartic- joint, with forward retraction of the anterior segular disc displacement [18]. Mattox [15] recom- ment. This approach has also been utilized by mends deliberate dislocation of the temporoman- Welsh and associates [11,12]. Additionally, the stydibular joint. This has the same limitations as loid process was removed and the digastric muscle subluxation of the temporomandibular joint and was divided. These authors described a wire fixafurthers the potential for intraarticular pathology to tion technique of the segments and did not allow develop. The performance and maintenance of ei- their patients to chew for at least three weeks. With ther of these maneuvers in the edentulous patient is lateral rotation of the proximal segment, the patient is at increased risk of developing both temporomandifficult. Many authors have promoted division or resec- dibular joint dysfunction and facial nerve palsey. tion of various muscular attachments with and This stabilization technique did not assure anatomic without removal of the mastoid process. DePalma mandibular repositioning, nor did it allow the pa[11 described dividing the stylohyoid and digastric tient to resume immediate postoperative mandibumuscles as weld as the ansa hypoglossi. Purdue and lar function. The techniques we describe provide a new and associates [3], reported a technique utilizing preand postauricular incisions allowing dissection of perhaps superior option for enhanced exposure of the parotid gland anteriorly, resection of the digas- the high ICA lesion. These osteotomies allow extric muscle from the mastoid process, avulsion of cellent manipulation of the posterior ramus and the styloid process with resection of the stylohyoid angle of the mandible with minimal stress to the muscle, and radical mastoidectomy. Deficiencies temporomandibular joint, parotid gland, and facial with these techniques include compromised Zone nerve. They can be performed on edentulous or III access, decreased mandibular range of motion dentate patients without developing intraoral comfrom resection of the digastric and stylohyoid mus- munications. The use of rigid fixation with cles, which we have observed in our patients, and preadapted bone plates and screws provides anatomic reapproximation and allows the patient to increased potential for nerve injury. A more radical approach has been described by function normally in the immediate postoperative Fisch and colleagues [9]. He recommended a radi- period. The stability provided by the bone plate cal mastoidectomy with obliteration of the middle eliminates the need for maxillomandibular fixation ear and resection of the mandibular condyle. The for anatomic reapproximation. Most patients are postsurgical functional problems resulting from this able to tolerate a soft diet within one week [16]. The preadaptation of the bone plate prior to completion technique are obvious. Various osteotomies to displace the angle of the of the osteotomy is a simple modification of procemandible into a position providing better access to dures performed routinely by oral and maxillofacial Zones II and III have been attempted. Batsdorf and surgeons across the nation. It assures anatomic Gregorius [4] used a horizontal osteotomy of the repositioning and fragment stabilization sufficient ramus superior to the mandibular foramen and a for mandibular function in the immediate postopervertical oblique osteotomy in the third molar re- ative period. Complications of these procedures are rare but, gion, anterior to the masseter attachment. This allowed lateral manipulation of the angle and pos- as with any mandibular osteotomy, include paresterior border of the mandible. The segment was thesia of the inferior alveolar nerve, inappropriate later wired back into position. Balagura and co- separation of the proximal and distal segments workers [5] modified the osteotomies of Batsdorf (which can be rectified with further modified osteotand Gregorius for use in edentulous patients. A omies), infection and bony nonunion [14,161. Ideally, the sagittal split osteotomy should be modified incision allowed access to the parasymphysis region of the mandible. The mandible was utilized. It provides a larger bone contact area for
472
ENHANCED SURGICAL EXPOSURE FOR THE EXTRACRANIAL ICA
healing and allows additional fixation, promoting faster healing and recovery. The sagittal split osteotomy is done prior to exposing the ICA to prevent oral contamination. Mandibular stabilization is accomplished after the neck incision is closed and protected. Careful preoperative evaluation of the patient and determination of the level of the lesion in the ICA is paramount to the decision to begin the operation with a sagittal osteotomy. Nevertheless, if the preoperative evaluation is ambiguous, the ICA dissection can be performed first. If improved access is deemed necessary intraoperatively, the extraoral vertical ramus osteotomy is accomplished through the ICA incision.
CONCLUSIONS This paper introduces modifications of two common surgical procedures performed routinely by oral and maxillofacial surgeons to correct facial deformities. The vascular surgeon can utilize these well established procedures to help obtain direct visualization of the high extracranial (Zone III) internal carotid artery.
REFERENCES 1. DEPALMA RG. Optimal exposure of the internal carotid artery for endarterectomy. Surg Gynecol Obstet 1977;144: 24%250. 2. FRY RE, FRY WJ. Extracranial carotid artery injuries. Surgery 1980;88:581-586. 3. PURDUE GF, PELLIGRINI RV, ARENA S. Aneurysms of the high internal carotid artery: a new approach, Surgery t 981 ;89:268-270. 4. BATZDORF U, GREGORIUS FK. Surgical exposure of the high cervical carotid artery: experimental study and review. Neurosurgery 1983;13:657--661.
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ANNALS OF VASCULAR SURGERY
5. BALAGURA S, CARTER JB, ANDGOSSETT DL. Surgical approach to the high subcranial internal carotid artery. Neurosurgery 1985;16:402-405. 6. HANS SS, SHAH S, HANS B. Carotid endarterectomy for high plaques. Am J Surg 1989;157:431-434. 7. THOMPSON JE. Carotid endarterectomy for high plaques (editorial comment). Am J Surg 1989;157:434--435. 8. CALLOW AD. Cerebrovascular insufficiency. In: HAMOVICI H, CALLOW AD, ERNST CB, DEPALMA RG, HOL° LIER LH (eds). Haimovici's Vascular Surgery. Norwalk, CT: Appleton and Lange, 1989, pp 72%730. 9. FISCH UP, OLDRING DJ, SENNING A. Surgical therapy of internal artery lesions at the skull base and temporal bone. Otolaryngol Head Neck Surg 1980;88:548-554. 10. WYLIE EJ, E H R E N F E L D WK. Extracranial Occlusive Cerebrovascular Disease: Diagnosis and Management. Philadelphia: W.B. Saunders, 1970. 11. WELSH P, PRADIER R, REPETTO R. High exposure of the carotid artery for difficult lesions. In: BERGAN J J, YAO JST (eds). Cerebrovascular Insufficiency. New York: Grune and Stratton, 1983, pp 433-447. 12. WELSH P, PRADIER R, REPETTO R. Fibromuscular dysplasia of the distal cervical internal carotid artery. J Cardiovasc Surg 1981;22:321-326. 13. FISCHER DF Jr, CLAGETT GP, PARKER JI, et al, Mandibular subluxation for high carotid exposure. J Vasc Surg 1984;1:727-733. 14. DOSSA C, SHEPARD AD, WOLFORD G, et al. Distal internal carotid exposure: a simplified technique for temporary mandibular subluxation. J Vasc Surg 1990;12:319-325. 15. MATTOX KL. Vascular trauma. In: HAIMOVICI H, CALLOW AD, ERNST CB, DEPALMA RG, HOLLIER LH (eds). tIaimovici's Vascular Surgery. Norwalk, CT: Appleton and Lange, 1989, pp 373. 16. TERRY BC, WHITE RP. Mandibular ramus surgery. In: PROFFIT WR, WHITE RP (eds). Surgical-Orthodontic Treatment. St. Louis: Mosby Year Book, 1991, pp 264-282. 17. RUGH JD, JOHNSON RW. Mandibular movements. In: MOHL ND, ZARB GA, CARLESON GE, RUGH JD (eds). A Textbook of Occlusion. Chicago: Quintessence Books, 1988, pp 131. 18. BELL WE. Temporomandibular Disorders: Classification, Diagnosis and Management. Chicago: Yearbook Medical Publishers Inc., 1986, pp 194-198,
