Year: 2002 Vol. 68 Ed. 4 - (8º)
Artigo Original
Pages: 502 to 509
PDF PT Image-Guided Endoscopic Sinus and Skull Base Surgery
Author(s):
Aldo C. Stamm 1,
Shirley Pignatari 2,
Bruno B. Sebusiani,
Marcos C. Galati 3,
Sérgio Mitsuda3,
Rainer G. Haetinger 4
Keywords: image-guided surgery, paranasal surgery, skull base surgery
Abstract:
Introduction: Although the paranasal sinuses and skull base surgeries have improved dramatically in the last two decades, especially due to advances in surgical instruments, endoscopic visualization and diagnosis procedures; complications of variable degree may still occur. The image-guided system is a very modern technology developed to help the surgeon to identify critical anatomic landmarks, conceived to provide more safety to the surgical procedures. Aim: The objective of this study was to evaluate the utility, the most important surgical indications, and the safety of this system, based on our experience with the image-guided system in paranasal sinuses and skull base surgeries. Material and method: We analyzed 20 patients undergone image-guided endoscopic paranasal sinuses and skull base surgery at São Paulo ENT Center, from November 2000 up to September 2001. Eleven (55%) of all patients were female, and the other nine ones (45%) were male. The utility, indications and safety of the system were evaluated according to subjective and objective criteria. 1. Utility: based on the need of the system by the surgeon during the surgical procedure; no need, low, moderate and high. 2. Indications: were analyzed according to the surgeries or surgical areas in which the system was required most. 3. Safety: based on the occurrence or absence of intraoperative and postoperative complications. Results: The system was used in all surgeries, although its need showed to be variable in each one. It was mostly required in surgeries of the skull base, revisional cases and surgeries in which the frontal recess had to be accessed. There was no occurrence of intra or post-operative complications. Conclusion: Although not essential, the image-guided system has shown to be useful and safe during endoscopic surgery, providing specific anatomical localization, mainly in patients with extensive disease, modified anatomic landmarks, frontal recess disease, sphenoid sinus, revisional cases or skull base lesions.
Introduction
Despite the significant progress and advent of new equipment in Otorhinolaryngology, including surgical instruments, video endoscopy and imaging techniques, nose, paranasal sinuses and skull base endoscopic surgeries still present high frequency of complications.
Nasosinusal and skull base endoscopic surgeries can be considered very common procedures, performed on average 250,000 times in the USA annually. Even though most of these procedures are complication-free, severe lesions are detected, especially among less experienced surgeons. It is important to point out that complications derived from mistakes in nasosinusal endoscopic surgeries are still the main causes for legal suits against physicians in the USA1.
It is estimated that low morbidity such as minor bleedings and synechia are present in 2 to 21% of the patients submitted to paranasal sinuses endoscopic surgery5, 17. High morbidity complications such as orbital lesions, among which we can include edema, ecchymosis, hematoma, extra-ocular muscle damage, optic nerve and intracranial damage, such as CSF leak, hemorrhage and intracranial hematoma, cerebral tissue lesion, meningitis, cerebral abscess, pneumoencephalus, and cranial nerve damage (olfactory, 3rd, 4th, 5th, 6th cranial nerves) are less frequent. Among the intracranial complications, CSF fistula is the most common one, normally occurring at the level of the roof of the ethmoidal sinus (ethmoidal fovea) and lamina cribosa. Vascular lesions normally occur at the level of the terminal branches of the maxillary artery and anterior and posterior ethmoid arteries. Lesions of the internal carotid artery and cavernous sinus are extremely rare.
It is believed that a great part of the complications are resultant from particularities inherent to the patient (anatomical variations, advanced disease, previous surgeries) and to the conditions of the surgical act (significant intra-operative bleeding). We should not, however, disregard the responsibility of the surgeon, especially owing to lack of anatomy knowledge and appropriate professional training.
Computer-guided endoscopic surgery aims at minimizing such complications, helping the surgeon to precisely locate intra-operatively the anatomical structures. The first navigation systems used stereotactic frameless, fixed to the head of the patient, and they were basically applicable to neurosurgery. This system presents low resolution, limited anatomical visualization on medial and lateral plans and used radioactive material. Despite the limitations, this technology proved to be very useful to support the localization of surgical instruments in relation to the skull base, frontal recess, ethmoidal fovea, posterior ethmoidal cells and sphenoid sinus3. Subsequently, new requirement was developed for nasosinusal surgeries, using articulated mechanical arms for intra-operative anatomic location, discarding the fixed frame on the patient (ISG Technologies, Mississauga, Ontario, Canada). More recently, a system that does not require the mechanic arm nor the frame was introduced, increasing considerably its use in nasosinusal and skull base endoscopic surgeries16. Computer-guided surgical equipment is divided into two groups: the optic system (that uses infrared light) and the electromagnetic system.
Last generation equipment has demonstrated high degree of precision, supporting the performance of transnasal endoscopic surgery. The use of this three-dimensional navigation system provides information about the anatomical structures of the operative field, creating an individual anatomical atlas based on the preoperative computed tomography. The main advantage of the computer-based system is greater safety provided by precise intra-operative anatomic location, minimizing the risks of complications caused by the surgical procedure. The studies by Zinreich19 and Anon1 presented an accuracy level between 1 and 3mm in anatomical location of various nasal-sinusal structures. In addition, the use of this system to surgically improve the knowledge of less experienced professionals (such as resident physicians, for example) has been reported by Cassiano et al.4, who demonstrated statistically significant difference concerning the identification of critical anatomical structures and absence of intracranial complications in the group of residents that used computer-assisted endoscopic surgery when compared to the group that did not. In addition, according to researchers, besides promoting the precise recognition of anatomical landmarks during nasosinusal endoscopic surgeries, the use of computer-guided endoscopic surgery provides physicians with a very high level of personal satisfaction, owing probably to the top technology employed and the reduced surgical risk12.
The purpose of the present study, based on the analysis of our skull base and nasosinusal surgeries, was to assess the use and safety of the system, as well as to check the situations in which the use of the computer-guided system would be highly indicated.
MATERIAL AND METHOD
In the present study, we assessed 20 patients submitted to paranasal sinuses and skull base endoscopic surgical procedures, supported by three-dimensional navigation systems in the period of November 2000 to September 2001, in the Center of Otorhinolaryngology and Speech and Language Pathology and Audiology of São Paulo - Hospital Professor Edmundo Vasconcelos. Eleven (55%) of the patients were female and 9 (45%) were male subjects. Ages varied from 16 to 74 years.
The patients included were all older than 12 years of age and had paranasal sinuses and skull base diseases with precise surgical indication. All patients signed the informed consent form concerning the use of the equipment.
Patients with blood dyscrasia, cranial-encephalic malformations and disabling diseases were excluded from the study.
All patients in the study were submitted to conventional endoscopic surgery, assisted by computer-guided images and operated by the same surgeon. The use of the navigation system was not added as an extra cost to the surgical treatment.
The utility and indication of the system were assessed by the surgeon, following subjective criteria:
1. Utility: based on the need to use the system during the surgery (none, little, moderate, high).
2. Indications: the most important indications were assessed according to surgeries or surgical areas in which the surgeon frequently required the system to help him/her.
3. Safety: assessed by occurrence of complications during and after the surgery.
Navigation System
The navigation system used in this study was LandmarX - computed image-guided tracking system, Medtronic-Xomed, Jacksonville, Florida, USA, which uses three-dimensional reconstruction of the patient's anatomy based on preoperative computed tomography images. The system consists of infrared sensors located in the articulated arm over the computer, which detects the instrument movement in relation to the surgical field. Thus, the surgical instrument used has small signal emitters that provide information to the sensors, hence informing precisely the location of the instrument in the surgical field. So that the computer can precisely recognize and locate the surgical material, it is necessary to previously calibrate the navigation system before each surgery. Thus, we adjusted the equipment, identifying predetermined fixed points on the head of the patient, correlating these points visualized by CT images, and the points existing in the headframe coupled to the patient's head. Therefore, the computer could three-dimensionally map the operative field. The use of the headframe enabled the compensation of minor head movements made during the procedure, dispensing new calibrations. If well performed, calibration provides precision below 1.0mm in relation to intra-operative anatomic position. In our patients, the mean was 1.0mm. After the calibration, the navigation system provided the precise location of the instrument on the computer monitor, as the intersection point of three lines that move in real time in stored CT images. We can observe that the space contained inside the green and yellow circles is within 1 and 2 mm precision, respectively (Figure 1).
Results
1. Assessment of System Utility:
The equipment was used in all surgeries, although frequency and need varied according to each surgery. In Table 1 we can observe the relation of all operated cases with the navigation system and the needs of equipment use.
2. Assessment of the Most Important Indications:
Surgeries and areas in which the surgeon required the most the system were: skull base surgeries, revisional surgeries without anatomical landmarks and frontal sinus and recess surgery.
3. Assessment of System Safety:
No patients presented intra or post-operative complications.Table 1. Distribution of patients submitted to computer-guided endoscopic surgery according to sex, age, diagnosis, utility and complications.
Legend: F= female; M= male;
Discussion
Paranasal sinuses and skull base endoscopic surgeries have been benefited by the use of three-dimensional navigation system owing to the characteristic anatomy of the region, with stationary bone limits that suffer modifications as the surgical procedure progresses. However, this system has proven to be useful in orthopedic, neurological and cardiac surgeries, minimizing the risk inherent to the surgery19.
The main obstacle for the use of the system is still its high cost. Systems used only by otorhinolaryngologists cost between US$150,000 and US$195,000. Systems available for more than one surgical area (for example, a system adaptable to both the otorhinolaryngologist and the neurosurgeon) are even more expensive15. Operational cost is added by the use of disposal materials, developed especially for the procedure. Another disadvantage is the need to have an additional pre-operative CT scan, even after the definition of diagnosis and operative planning.
The endoscopic surgery, as well as any other surgical procedure, reaches the maximum success with the minimum structural and functional damage, especially iatrogenic. However, the limitation of the operative field in the endoscopic surgery can increase the risk of accidents. It is especially true in patients with extensive tumors, patients submitted to various surgical procedures or anatomical variations caused by the disease itself19.
In our study, the system was useful in all surgeries, although it has not been essential in most of the cases. It is important to refer to the level of surgical stress, which was considerably reduced, especially in critical or doubtful areas. We could also observe that with the use of the navigation system it was possible to perform a more complete operative intervention, because the surgeon was certain about all affected sinuses, since they were inspected. It is especially valid in cases of trans-operative doubts, such as for example in surgeries of the frontal sinus and supra-orbital ethmoidal cells (opening or not some specific cells) and in localized tumor resections of the skull base, which diffusely compromise the operative region. Even though we did not have any case of intra or post-operative complication resultant from surgery or the method employed, it is important to mention that our rate of complications in similar surgeries, without the use of the navigation system, is also very low, about 0.94%.
In the studied literature we did not find studies showing statistically significant difference in rate of complications or frequency of revisional surgeries. In addition, there are few studies that show improvement of surgical results or shortening of surgical time using computer-guided surgical technology.
As to operation time using the navigation system, literature data are compatible with our study, showing that only 10 minutes are necessary to install the system and collect the image, approximately the same time necessary for injecting vasoconstrictor agents to act. It is likely that this additional period has been compensated during the surgical act, thanks to the time gained in precisely identifying the anatomical structures involved, enabling faster surgical procedures.
Based on the 20 operated patients, the most important indications to use the system, as well as the ones described by other authors5, were in extensive surgeries with poorly defined anatomical limits, revisional surgeries, frontal recess and sinus surgery, and sphenoid sinus surgery. In our study, the computer-guided surgical system proved to be useful also in cases of tumors and those that did not involve the skull base.
The follow-up of these patients for a prolonged period of time is necessary to assess the real benefits of the surgical treatment when compared to the results of patients operated on without this technology.
Conclusion
Based on the results of our study we concluded that:
1. The system of computer-guided endoscopic surgery is useful in surgeries of paranasal sinuses and skull base, although it is not essential;
2. The main indications for use are in patients with extensive disease, frontal recess and sinus surgery, revisional surgery, anatomical abnormalities, or in cases of tumors involving or not the skull base;
3. The system can be considered a precise and safe method.
References
1. Anon JB, Lipman SP, Oppenheim D, Halt RA. Computer-Assisted Endoscopic Sinus Surgery. Laryngoscope 1994;104(7):901-905.
2. Bale RJ, Vogele M, Freysinger W, Gunkel AR, Martin A, Bumm K, Thumfart WF. Minimally Invasive Head Holder to Improve the Performance of Frameless Stereotactic Surgery. Laryngoscope 1997;107(3): 373-377.
3. Cartellieri M, Vorbeck F. Endoscopic Sinus Surgery Using Intraoperative Computed Tomography Imaging for Updating a Three-dimensional Navigation System. Laryngoscope 2000;110(2):292-296.
4. Cassiano RR, Numa WA. Efficacy of computed tomographic image-guided endoscopic sinus surgery in residency training programs. Laryngoscope 2000;110(8): 277-1282.
5. Davis WE. Middle Meatus Antrostomy: Patency Rates and Risk Factors. Otolaryngol Head Neck Surg 1991;104:467.
6. Elias WJ, Chadduck JB, Alden TD, Laws ER. Frameless Stereotaxy for Transsphenoidal Surgery. Neurosurgery 1999;45(2):271-277.
7. Fried MP, Kleefield J, Gopal H, Reardon E, Ho BT, Kuhn FA. Image-Guided Endoscopic Surgery: Results of Accuracy and Performance in a Multicenter Clinical Study Using an Electromagnetic Tracking System. Laryngoscope 1997;107(5):594-601.
8. Grevers G, Menauer F, Leunig A, Caversaccio M, Kastenbauer E. Navigationschirurgie bei Nasen-nebenhöhlenerkrankungen. Laryngo-Rhino-Otol 1999;78:41-46.
9. Gunkel AR, Freysinger W, Thumfart WF. Computer-Assisted Surgery in the Frontal and Maxillary Sinus. Laryngoscope 1997;107(5):631-633.
10. Loehrl TA, Toohill RJ, Smith TL. Use of Computer-Aided Surgery for Frontal Sinus Ventilation. Laryngoscope 2000;110(11):1965-1967.
11. Luxenberger W, Köle W, Stammberger H, Reittner P. Computerunterstützte Nasennebenhöhlenchirurgie - Der Standard von morgen? Laryngo-Rhino-Otol 1999;78: 318-326.
12. Metson RB, Cosenza MJ, Cunningham MJ, Randolph GW. Physician Experience With an Optical Image Guidance System for Sinus Surgery. Laryngoscope 2000;110(6):972-976.
13. Ossoff RH, Reinisch L. Computer-Assisted Surgical Techniques: A Vision for the Future of Otolaryngology - Head and Neck Surgery. J. Otolaryngol 1994;23(5):354-359.
14. Roth M, Lanza DC, Zinreich J, Yousem D, Scanlan KA, Kennedy DW. Advantages and Disadvantages of Three-dimensional Computed Tomography Intraoperative Localization for Functional Endoscopic Sinus Surgery. Laryngoscope 1995;105(11):1279-1286.
15. Sillers MJ, Gibbons MD. Cost Analysis of Computer-Aided Surgery of the Paranasal Sinuses. Oper Tech Otolaryngol - Head and Neck Surg 2001;12:51-54.
16. Smith TL, Loehrl TA, Smith MM. Surgery of the Frontal Recess and Sinus: The Utility of a Computed Tomography Image-Guidance System in Selected Cases. In: Oper Tech Otolaryngol - Head and Neck Surg 2001;12:7-12.
17. Stankiewicz JA. Complications in Endoscopic Sinus Surgery. Otolaryngol Clin N Amer 1989;22:749.
18. Weber R, Draf W, Kratzsch B, Hosemann W, Schaefer SD. Modern Concepts of Frontal Sinus Surgery. Laryngoscope 2000;111(1):137-146.
19. Zinreich SJ. Image-guided Functional Endoscopic Sinus Surgery. In: Kennedy DW, Bolger WE, Zinreich SJ. (eds.). Diseases of the Sinuses - Diagnosis and Management. Hamilton: B.C. Decker, 2001. p.357-67.
[1] Director of Center of Otorhinolaryngology and Speech and Language Pathology and Audiology of São Paulo - Hospital Professor Edmundo Vasconcelos.
2] Physician, responsible for the Sector of Pediatric Otorhinolaryngology, Center of Otorhinolaryngology and Speech and Language Pathology and Audiology of São Paulo - Hospital Professor Edmundo Vasconcelos; Professor, Discipline of Pediatric Otorhinolaryngology, Federal University of São Paulo/EPM.
[3] Resident Physician, Center of Otorhinolaryngology and Speech and Language Pathology and Audiology of São Paulo - Hospital Professor Edmundo Vasconcelos.
[4] Responsible for the Division of Head and Neck Radiology, Med-Imagem - Hospital Beneficência Portuguesa de São Paulo.
Affiliation: Center of Otorhinolaryngology and Speech and Language Pathology and Audiology of São Paulo - Hospital Professor Edmundo Vasconcelos.
Address correspondence to: Rua Borges Lagoa 1450 - 04038-905 - Vila Clementino - São Paulo - Tel. (55 11) 5080-4357
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