Efficacy of computed tomographic image--guided endoscopic sinus surgery in residency training programs

Comparison of equine paranasal sinus trephination complications and outcome following standing computed tomography, radiography and sinoscopy guided approaches for the treatment of sinusitis

OBJECTIVE

The recent availability of standing computed tomography (CT) for equine paranasal sinus disease has enhanced diagnosis and enabled more targeted surgery compared to radiography and sinoscopy. To date, there have been no studies which have critically evaluated the benefit of preoperative CT versus radiography and sinoscopy on complications and outcome in horses undergoing sinus trephination.

STUDY DESIGN

Retrospective study.

ANIMALS

A total of 229 equids.

METHODS

The medical records of equids (229) presented for sinusitis treated via trephination that had CT, radiography and/or sinoscopy at time of surgery between 2009 and 2022 were reviewed. Outcome and complications were evaluated for six different pre- and intraoperative imaging modalities.

RESULTS

The six groups did not differ in demographics or disease category, though equids with less weight (p = .0179) and shorter disease duration (p = .0075) were more likely to have radiography and sinoscopy based surgical planning. Short-term postoperative complications occurred in 30.1% and were higher in groups using preoperative CT imaging (p = .01), with hemorrhage being the most common surgical complication. Following initial trephination surgery, 57.0% (127/223) of cases resolved and there was no difference between the imaging groups. Final resolution after follow-up medical or surgical treatment increased to 94.6% (211/223) and was not different between the imaging groups or between primary or secondary sinusitis. Additional nasal fenestrations to improve sinonasal drainage, maxillary septal bulla fenestrations and trephinations to treat nasal conchal bullae were made in the CT groups.

CLINICAL SIGNIFICANCE

CT provided additional diagnostic information and enabled different surgical approaches but did not improve resolution in this study population.

Anterior Skull Base Surgery via Endoscopic Endonasal Approach: Outcomes and Analysis

BACKGROUND

This study was retrospectively conducted to evaluate the postoperative surgical results of our patients with anterior skull base mass, defect, and/or cerebrospinal fluid rhinorrhea who underwent reconstruction via endoscopic endonasal approach and to share our experiences.

METHODS

Sociodemographic features of patients who had undergone endoscopic surgery in our clinic due to anterior skull base mass, defect, or rhinorrhea were evaluated in terms of etiological factors, surgical method, pathology, postoperative complications, need for revision surgery and comorbid disease.

RESULTS

A total of 131 patients were included; 76 were male and mean age was 36.2 years. Endoscopic endonasal surgery was performed for nasal mass (70.2%) in 92 cases, rhinorrhea (17.6%) in 23 cases, chronic sinusitis (7.6%) in 10 cases, and gunshot injury (4.6%) in 6 cases. After surgery, benign mass pathology was detected in 75 patients and malignant mass pathology was detected in 23 patients. Osteoma was the most common among benign formations, and squamous cell carcinoma was the most common among malignant formations. The most common cause of surgical revision was nasal masses (25 cases, 77.4%).

CONCLUSION

Endoscopic intracranial interventions and increased anterior skull base surgery are garnering increased interest of physicians as endoscopic approaches are gaining popularity in recent years. Successful results are achieved through appropriate diagnostic methods and endoscopic approaches. Success rates will be further increased due to developing technology and imaging methods, while the risk of complications and revision surgery will be further reduced.

Three-dimensional virtual planning for nodule resection in solid organs: A systematic review and meta-analysis

OBJECTIVES

To systematically review the effects of 3D-imaging virtual planning for nodule resection in the following solid organs: lung, liver, and kidney.

METHODS

MEDLINE, EMBASE, and Cochrane Library were searched through September 31, 2020 to include randomized and non-randomized controlled studies that compared outcomes of surgical resection of lung, liver, or kidney nodule resection with and without 3D virtual planning with computed tomography. From each article, the mean operation time (OT), mean estimated blood loss (EBL), mean postoperative hospital stay (POHS), and the number of postoperative events (POE) were extracted. The effect size (ES) of 3D virtual planning vs. non-3D planning was extracted from each study to calculate the pooled measurements for continuous variables (OT, EBL, POHS). Data were pooled using a random-effects model.

RESULTS

The literature search yielded 2397 studies and 10 met the inclusion criteria with a total of 897 patients. There was a significant difference in OT between groups with a moderate ES favoring the 3D group (ES,-0.56; 95%CI: 0.91,-0.29; I² = 83.1%; p < .001). Regarding EBL, there was a significant difference between 3D and non-3D with a small ES favoring IGS (ES,-0.18; 95%CI: 0.33,-0.02; I² = 22.5%; p = .0236). There was no difference between the 3D and non-3D groups for both POHS (POHS ES,-0.15; 95%CI: 0.39,0.10; I² = 37.0%; p = .174) and POE (POE odds ratio (OR),0.80; 95%CI:0.54,1.19; I² = 0.0%; p = .0.973).

CONCLUSIONS

3D-imaging planning for surgical resection of lung, kidney, and liver nodules could reduce OT and EBL with no effects on immediate POHS and POE. Improvements in these perioperative variables could improve medium and long-term postoperative clinical outcomes.

Role of Image Guided Navigation in Endoscopic Surgery of Paranasal Sinuses: A Comparative Study

The aim of the current study is to share our experience with surgical outcomes of Functional Endoscopic Sinus Surgery using an image-guidance system. The study was a randomised control trial with the comparison between two groups. Image guidance system (Electromagnetic) was used for endoscopic surgery on patients with disease of the paranasal sinuses (n = 30). Results were compared with those in control patients who underwent similar surgery without image guidance during the same period (n = 30). The operating room time (image-guidance group, 165.68 ± 6.55 min [mean ± SE]; control group, 163.33 ± 5.43 min), Intraoperative anatomical localization was accurate to within 2 mm. Intraoperative blood loss (image-guidance group, 566.67 ± 62.23 ml [mean ± SE]; control group, 636.33 ± 72.59 mL) and complication rates (image-guidance group, 3.3%; control group, 3.3%) did not differ significantly between groups. We find image guidance system a useful tool with accuracy of 2 mm. Actual intraoperative time, blood loss and complications do not differ significantly with or without the use of IGS.

Virtual Simulator as a Training Tool for Endonasal Surgery

Background

Virtual simulation could be an important tool for medical and surgical training as well as education. The efficacy of a simulator for endoscopic nasal procedures in a training program was evaluated.

Methods

The simulator is a medical and scientific tool for visualizing and interacting with three-dimensional volumetric data. Twenty endonasal operations with chronic rhinosinusitis were simulated by two 3rd-year residents and proctored by the senior surgeon 1 day before the actual surgery was performed with an endoscope and computer-aided surgery. A questionnaire was established.

Results

The surgical simulator may provide a better understanding of the morphology of the paranasal sinuses with a minor impact on performance of endoscopy by junior residents. Disadvantages identified were time consumption, absence of force feedback, and subtle handling of the joysticks.

Conclusion

The virtual simulator allows the nonendoscopically nasal trained surgeon to understand and practice endonasal surgery using real-patient data but failed to make an impact on operating room performance. Furthermore, the simulator's effectiveness was limited by the absence of force feedback, subtle handling of the joysticks, and considerable time consumption.

Image-Guided Endoscopic Orbital Decompression for Graves' Orbitopathy

Objectives: We studied the efficacy and safety of image-guided balanced orbital decompression for Graves' orbitopathy.

Methods: The data of 24 patients (45 orbits) were reviewed for demographics, ophthalmologic outcomes, and complications in regard to image-guided (18 orbits) versus non-image-guided surgery (27 orbits).

Results: Overall, all patients had a reduction in proptosis (mean reduction, 6.2 mm in proptosis) as measured by Hertel exophthalmometry. There was improvement in the visual acuity of all 12 orbits with preoperative acuity of 20/40 or worse and either complete resolution (38%) or improvement (62%) in the 16 orbits with optic neuropathy. These measures reached statistical significance. Despite subjective improvement in surgeon confidence, the use of image guidance did not result in a statistically significant difference in postoperative ophthalmologic outcomes. Medical and sinonasal complications were experienced by 11.1% and 18.5% of patients who underwent image-guided and non-image-guided orbital decompression, respectively.

Conclusions: Image guidance may be a useful adjunct to balanced orbital decompression for Graves' orbitopathy, but it was not associated with a statistically significant improvement in outcomes in this study.

Image-guided Localization of the Internal Auditory Canal via the Middle Cranial Fossa Approach

OBJECTIVE: We sought to determine the accuracy of an electromagnetic image guidance surgical navigation system in localizing the midpoint of the internal auditory canal (IAC) and other structures of the temporal bone through the middle cranial fossa approach.

MATERIALS AND METHODS: Seven fresh cadaveric whole heads were dissected via a middle cranial fossa approach. High-resolution CT scans were used with an InstaTrak 3500 Plus electromagnetic image guidance system (General Electric, Fairfield, CT). We evaluated the accuracy of identifying several middle cranial fossa landmarks including the midpoint of the IAC; the labyrinthine segment of the facial nerve; and the arcuate eminence, the carotid artery, and foramen spinosum.

RESULTS: We were able to identify the middle of the IAC within 2.31 mm (range 0.65-7.52 mm, SD 2.39 mm). The arcuate eminence could be identified within 1.86 mm (range 1.49-2.37 mm, SD 0.36 mm). We noted some interference when the handpiece was within 6 to 8 cm of the microscope.

CONCLUSION: Although computer-aided navigational tools are no substitute for thorough knowledge of temporal bone anatomy, we found the InstaTrak system reliable in identifying the midpoint of the IAC to within 2.4 mm through a middle fossa approach.

Stereotactic anatomical localization in complex sinus surgery: A systematic review and meta-analysis

OBJECTIVE

It is recognized that stereotactic anatomical localization (SAL) is a useful tool in endoscopic sinus surgery (ESS), but it may be most beneficial for complex rather than routine sinus procedures. This review sought to determine the safety and efficacy of SAL in complex indications for ESS.

DATA SOURCES

PubMed, EMBASE, Centre for Reviews and Dissemination, and the Cochrane Library were searched from inception up to April 4, 2014.

REVIEW METHODS

English studies comparing ESS with and without SAL in complex cases were included. Complex surgery included revision surgery, inverted papilloma, extensive sinus disease, or biopsy of tumors that are not exophytic. Safety outcomes included total, major, minor, orbital, dural, and major hemorrhage complications. Efficacy outcomes included operation completion, revision surgery, and patient-reported outcomes. Meta-analysis generated fixed-effects Mantel-Haenszel odds ratios (OR) and confidence intervals (CI).

RESULTS

A total of 2,381 studies were identified, of which nine met the inclusion criteria. Meta-analyses indicated a reduction in the likelihood of total (OR = 0.58; 95% CI, 0.37-0.92), major (OR = 0.36; 95% CI, 0.18-0.75), and orbital complications (OR = 0.38; 95% CI, 0.17-0.83). There was no demonstrated benefit of SAL at reducing revision surgery (OR = 0.64; 95% CI, 0.38-1.08), major hemorrhage (OR = 0.77; 95% CI, 0.29-2.06), or minor complications (OR = 0.85; 95% CI, 0.48-1.50).

CONCLUSION

Due to the rare outcomes under investigation, the included primary studies largely lacked the power to identify a statistically meaningful effect of SAL in ESS. However, meta-analyses of primary studies demonstrated a decreased likelihood of total, major, and orbital complications in complex ESS with the use of SAL.

Computer or not? Use of image guidance during endoscopic sinus surgery for chronic rhinosinusitis at St Paul's Hospital, Vancouver, and meta-analysis

BACKGROUND

The advantages and limitations of image guidance systems for endoscopic sinus surgery are unclear. We report our experience and present a meta-analysis of the evidence.

METHODS

We performed a retrospective analysis of endoscopic sinus surgery procedures performed with versus without image guidance. A total of 355 cases was included. Primary outcomes included complication rates and time to revision surgery. A literature search was conducted to enable identification and analysis of studies of similar comparisons.

RESULTS

Within 1.5 years of the index sinus surgical procedure, the risk of revision surgery was significantly higher for patients treated with non-assisted versus computer-assisted endoscopic sinus surgery (p = 0.001). Meta-analysis did not indicate a reduction in complications or revision surgery procedures with the use of image guidance systems, although the majority of included studies showed a non-significant reduction in revision surgery.

CONCLUSION

Our study offers some evidence that computer-assisted endoscopic sinus surgery may delay residual disease and reduce the requirement for revision surgery. Although this finding was not borne out in the meta-analysis, the majority of identified studies demonstrated a trend towards fewer revision procedures after computer-assisted endoscopic sinus surgery. This type of surgery may offer other advantages that are not easily measurable.

Navigation with the StealthStationtrade mark in Skull Base Surgery: An Otolaryngological Perspective

The introduction of computer-assisted navigation systems has played a significant role in assuring the integration and consistent intraoperative use of radiological information. We used a frameless stereotactic navigation system to treat 62 patients with a variety of skull base pathologies. The optoelectric appliance uses digital imaging information to locate surgical instruments in the operative area. The aim of this study was to evaluate the clinical accuracy, practicality, and impact of this navigation system on otolaryngological procedures. In conjunction with rigid head fixation and bone-anchored registration markers, the precision of registration was 0.8 mm and the accuracy of clinical measurements was less than 2 mm. With conventional fiducials and flexible head positioning, deviations were as large as 4.5 mm. The additional use of surface registration increased the precision of registration. Preoperative preparations took 15 to 35 minutes, depending on the complexity of the planning. Intraoperative computer support is an important aid to a surgeon's orientation, especially when a patient's anatomy is atypical. Navigation systems will likely improve the quality of surgery and facilitate training.

Level of complete dissection of the ethmoid sinuses with a computed tomographic image guidance system

OBJECTIVES

We sought to determine the adequacy of endoscopic total ethmoidectomy with the use of a computed tomographic (CT) image guidance system.

METHODS

Endoscopic ethmoid sinus dissections were performed on cadavers by otolaryngologists. All cadavers were scanned before dissection. On each side of the cadaver, the ethmoid sinuses were examined independently. A complete endoscopic ethmoidectomy was performed with a CT image guidance system. After the endoscopic ethmoidectomy, the cadaver underwent a postdissection CT scan. The postdissection CT images were then evaluated for the level of complete dissection of the anterior and posterior ethmoid sinuses.

RESULTS

There were 18 ethmoid sinuses in the study. One specimen underwent a complete total ethmoidectomy with no residual cells. There were 4 complete anterior ethmoidectomies and 5 complete posterior ethmoidectomies. Overall, the average numbers of residual anterior ethmoid and posterior ethmoid air cells were 1.39 and 1.22, respectively. This difference was not statistically significant. The skull base was dissected more completely than the lamina papyracea, with a significant difference (p = 0.03). There was no difference in terms of residual cells between the left and right ethmoid sinuses (p > 0.05).

CONCLUSIONS

Even with the use of a CT image guidance system, a complete ethmoidectomy was still difficult to achieve. Residual ethmoid sinus cells were more commonly found along the lamina papyracea than along the skull base.

Computer-aided endoscopic sinus surgery: a retrospective comparative study

BACKGROUND AND OBJECTIVES

Endoscopic sinus surgery (ESS), markedly improved with the introduction of new preoperative imaging techniques, intraoperative visualization tools, and the use of surgical navigation systems. In this retrospective study we evaluated the usefulness of CT-guided endoscopic sinus surgery and studied its advantages over conventional endoscopic sinus surgery.

METHODS

We retrospectively reviewed the records of 60 randomly chosen patients with chronic rhinosinusitis (CRS) and moderate-to-severe sinonasal polyposis, undergoing endoscopic sinus surgery with surgical navigation (n=30) and without navigation (n=30). Data on the operative note, time of surgery, complications, and recurrence rate were collected and analyzed.

RESULTS

Of the 60 patients, 40 (66.7%) were diagnosed with CRS and 20 (33.3%) had allergic fungal sinusitis. Primary surgery was performed in 37 (61.7%) and revision surgery was performed in 23 (38.3%) cases. The computer-aided surgery (CAS) group included 28 (93.3%) patients with extensive disease and 12 (40%) with bone erosions, with intraorbital or extradural extension, while the non-CAS group included 24 (80%) patients with extensive disease and seven (23.3%) with bone erosions, with intraorbital or extradural extension. The average operative time was approximately 13 minutes greater in the navigation group, with significant improvement in the recurrence rate (n=11, 36.7% in the non-CAS group; n=5, 16.7% in the CAS group), and intraoperative complications were fewer in the CAS group (two exposures of orbital fat in the non-CAS group; no complications in the CAS group).

CONCLUSION

Computer navigational systems appear to serve as a valuable adjunct in preoperative planning and safe intraoperative dissection.

Outcome of computer-assisted surgery in patients with chronic rhinosinusitis

Objective:

To compare the complication rates and outcome of computer-assisted versus non-computer-assisted functional endoscopic sinus surgery.

Methods:

We reviewed retrospectively the medical records of 276 patients who had undergone sinus surgery for chronic rhinosinusitis with (n = 108) or without (n = 168) computer assistance, from 1996 to 2004, to determine the incidence of complications and need for revision surgery.

Results:

The incidence of complications was 6.5 per cent in the computer-assisted group and 6.0 per cent in the non-computer-assisted group (p = 1.00). In the computer-assisted group, 9.2 per cent needed revision surgery, compared with 10.7 per cent in the non-assisted group (p = 0.84).

Conclusions:

Although our study found no significant difference in complications or revision rates, computer-assisted surgery serves as an important orientation aid during functional endoscopic sinus surgery.

Computer assistance for intraoperative navigation in ENT surgery

The intraoperative need for exact orientation during interventions in the paranasal sinuses and the augmented need for navigational aids in lateral skull base surgery have lead to the development of computer-aided tools during the last fifteen years. These tools, which provide the position of a tool or a pointer in the patient's preoperative radiologic imaging, have quickly gained a wide acceptance for revision surgeries and the surgical treatment of complex pathologies in Ear-, Nose- and Throat (ENT-) surgery. Currently, the use of such systems is spreading from academic centers to smaller hospitals and will become a standard tool in the near future. We review the present state of computer-aided surgery (CAS) systems, based on our experience as clinical and research centers with a long experience in the field, provide some technological background information and, based on selected cases, show the merits of this technology. The systems we have been working with cover a wide variety of intraoperative navigational systems in ENT surgery (Easy Guide, MedScan II, MKM, SNN, STN, SurgiGATE ORL, Treon, VectorVision, Viewing Wand, [without claiming completeness]), and virtually the whole area of ENT surgeries: macroscopic, (video-)endoscopic and microscopic procedures. The 3D tracking technologies involved cover mechanical, optical (active and passive), magnetic and robotic principles. The visualization tools used are computer monitors, video monitors, head-up-displays and the microscope's oculars, thus spanning the area from pointer-systems to real navigators and a surgical telepresence demonstrator, implementing the majority of available patient-to-image referencing strategies. Clinically, the systems can be operated with an acceptable accuracy of around 1 mm, whereas in laboratory settings and in cadaver studies application accuracy may be pushed to its limits: the physical resolution of the radiologic imaging used for navigation.

Accuracy of image-guided surgical systems at the lateral skull base as clinically assessed using bone-anchored hearing aid posts as surgical targets

OBJECTIVE

Image-guided surgical (IGS) technology has been clinically available for more than a decade. To date, no acceptable standard exists for reporting the accuracy of IGS systems, especially for lateral skull base applications. We present a validation method that uses the post from bone-anchored hearing aid (BAHA) patients as a target. We then compare the accuracy of 2 IGS systems-one using laser skin-surface scanning (LSSS) and another using a noninvasive fiducial frame (FF) attached to patient via dental bite-block (DBB) for registration.

STUDY DESIGN

Prospective.

SETTING

Tertiary referral center.

PATIENTS

Six BAHA patients who had adequate dentition for creation of a DBB.

INTERVENTION(S)

For each patient, a dental impression was obtained, and a customized DBB was made to hold an FF. Temporal bone computed tomographic (CT) scans were obtained with the patient wearing the DBB, FF, and a customized marker on the BAHA post. In a mock operating room, CT scans were registered to operative anatomy using 2 methods: 1) LSSS and 2) FF.

MAIN OUTCOME MEASURE(S)

For each patient and each system, the position of the BAHA marker in the CT scan and in the mock operating room (using optical measurement technology) was compared, and the distances between them are reported to demonstrate accuracy.

RESULTS

Accuracy (mean +/- standard deviation) was 1.54 +/- 0.63 mm for DBB registration and 3.21 +/- 1.02 mm for LSSS registration.

CONCLUSION

An IGS system using FF registration is more accurate than one using LSSS (p = 0.03, 2-sided Student's t test). BAHA patients provide a unique patient population upon which IGS systems may be validated.

[Computer-aided surgery of the paranasal sinuses and the anterior skull base]

Endoscopic or microscopic surgery for chronic rhinosinusitis with or without nasal polyps is a routine intervention in daily practice. It is often a delicate and difficult minimally invasive intervention in a narrow space, with a tunnel view of 4 mm in the case of endoscopy and frequent bleeding in chronically inflamed tissue. Therefore, orientation in such a "labyrinth" is often difficult. In the case of polyp recurrence or tumors, the normal anatomical landmarks are often missing, which renders orientation even more difficult. In such cases, computer-aided navigation together with images such as those from computed tomography or magnetic resonance imaging can support the surgeon to make the operation more accurate and, in some cases, faster. Computer-aided surgery also has great potential for education.

Image-Guided Technique in Neurotology

To date, clinical application of image-guided surgery (IGS) to otology/neurotology has been limited, but a large potential market and numerous applications support use. Such applications include control of surgical instruments (eg, turning off a drill when close to an anatomic boundary), robotic surgery (eg, robotic mastoidectomy), and minimally invasive surgery (eg, percutaneous cochlear implantation).

[The use of the BrainLAB Kolibri navigation system in endoscopic paranasal sinus surgery under local anaesthesia. An analysis of 35 cases]

BACKGROUND

As a result of technological advances, 3D-navigation systems are playing an increasingly important role in paranasal sinus and anterior skull base surgery.

PATIENTS AND METHODS

The BrainLAB Kolibri navigation system (BrainLAB, Heimstetten, Germany) was used in the surgical management of chronic sinusitis and nasal polyposis in 35 patients. Surgery was performed under local anaesthesia. In order to compare this technique with traditional methods, 35 additional patients underwent conventional surgery. A clinical plausibility test using specific anatomical landmarks was performed to evaluate intraoperative navigation accuracy. In addition, a standardised questionnaire was used to document setup and registration times. Standardised rating scales helped assess whether the system can make surgery safer.

RESULTS

It took approximately 5.8 min to set up the navigation system. The time required for system and patient positioning, including the attachment of the headband, was 4.2 min on average. Patient registration with the z-touch system was completed after an average of 4.2 min. It took an average of approximately 8.1 min to register a patient using the soft-touch system. The use of the navigation system increased the total time for preparation and surgery by approximately 50% in comparison to the conventional technique. An average accuracy of 1.5-2.3 mm in all three planes was measured. Participating surgeons felt that the system made surgery considerably safer.

CONCLUSIONS

The BrainLAB Kolibri navigation system offers good accuracy, a short setup time and an easy registration technique. The combination of these qualities and intuitive operation make this system a suitable option for routine use in paranasal sinus surgery. As a result of its compactness, the BrainLAB Kolibri navigation system can be moved easily between different operating rooms and can also be used in small facilities (e.g. container operating theatres in field hospitals).

Endoscopic pituitary surgery with and without image guidance: an experimental comparison

BACKGROUND

The combination of image guidance and endoscopy is the newest trend in pituitary surgery. To assess the impact of image guidance on EPS, we measured and calculated the accuracy of the system and compared some critical surgical steps with and without image guidance under experimental conditions in terms of surgical time and precision.

METHODS

Twenty cadaver heads were explored by standard endoscopic transsphenoidal surgical technique. Optic-radiologic correlations of topographic landmarks were photographed, and the system accuracy and actual visual accuracy were recorded. Some important anatomical parameters were measured in surgical field and on navigation system, and the differences were calculated and analyzed. Some critical surgical steps were recorded and compared between with and without image guidance.

RESULTS

The system accuracy (root mean square), calculated by the computer automatically, showed a mean value of 0.28 +/- 0.06 mm. In some cases, there was a small discrepancy between the visible position of the pointer and its counterpart on the navigation system; we coined this actual visual accuracy. The average value was 1.53 +/- 0.49 mm. The maximum difference between the measurements from the navigation system and from their actual visual counterparts was less than 7%. With and without image guidance, in normal anatomical conditioning, there was no statistically significant difference between the duration of ostium sphenoidale exposure and sellar window creation; however, in anatomical variations, the surgical time was shown to be significantly shorter when navigation was used.

CONCLUSION

We have demonstrated in this experimental setting that the electromagnetic tracking image guidance possesses a high accuracy at millimetric level and therefore provides precise localization and orientation in EPS. With the assistance of neuronavigation system, it is advantageous not only in saving operating time, but also, more importantly, in enhancing the orientation, thus, rendering surgeries safer and more efficient. During the in vivo pituitary surgery, EPS with image guidance can provide accurate and reliable stereoinformation to achieve better results with lesser risks, particularly in complex cases or in reoperations, even in the hands of experienced surgeons.

Quality of life and complications following image-guided endoscopic sinus surgery

OBJECTIVES

To compare the quality of life (QOL) outcome and incidence of complications following image-guided versus non-image-guided endoscopic sinus surgery (ESS).

STUDY DESIGN

The operative, office, and hospital charts of patients who underwent primary ESS for chronic sinusitis by a single surgeon with (2002-2005) or without (1997-2002) image guidance were reviewed for patient demographics, incidence of complications, and revision procedures. A telephone survey was used to administer the QOL survey to both cohorts.

RESULTS

In comparing patients who underwent image-guided (60) versus non-image-guided surgery (179), respectively, there was no statistically significant difference in the incidence of major intraoperative complications (6.6% vs 5.6%), major postoperative complications (5% vs 3.9%), revision procedures (6.6% vs 7.3%), and postoperative SNOT-20 symptom scores (23.6 vs 23.4). A higher incidence of intraoperative cerebrospinal fluid leak was noted in the non-image-guided group (0% vs 2.2%).

CONCLUSIONS

Our study does not demonstrate an improvement in the incidence of complications, need for revision procedures, or quality-of-life outcome for patients undergoing primary ESS for chronic sinusitis. The use of image guidance may result in a lower incidence of skull base trauma and cerebrospinal fluid leak.

EBM RATING

B-2b.

Computer-aided surgery of the paranasal sinuses and skull base

Endoscopic sinus surgery is one of the most common surgical procedures in otolaryngology. However, the location of the orbit and intracranial contents in close proximity to the paranasal sinuses makes endoscopic sinus surgery potentially hazardous. Otolaryngologists have employed computer-aided surgery, or image-guided surgery, over the past two decades to enhance surgeon confidence, allow more thorough surgical dissections and possibly reduce the complication rate of endoscopic sinus surgery. Computer-aided surgery utilizes preoperative imaging to provide real-time localization of surgical instruments in the surgical field. Although computer-aided surgery originated in the neurosurgical realm, otolaryngologists soon appreciated that this technology could assist in identifying critical orbital or intracranial structures surrounding the paranasal sinuses, and potentially aid in decreasing complications. In this article, the history of image-guidance systems and their application to surgery of the paranasal sinuses and skull base will be reviewed. The components of computer-aided surgery systems and the currently available technologies for surgical instrument tracking are discussed, as well as the advantages and disadvantages of each of the tracking technologies. In addition, issues relating to the accuracy of image-guidance systems are examined. A number of institutional series noting surgeon experience with computer-aided surgery in the domain of paranasal sinus surgery are reviewed. Furthermore, the authors evaluate the utility of image-guidance technology beyond the paranasal sinuses and skull base, such as its use in surgery of the pituitary gland and pterygopalatine fossa, research and resident education. Finally, potential future applications of computer-aided surgery technology are discussed.

In vitro assessment of image-guided otologic surgery: submillimeter accuracy within the region of the temporal bone

OBJECTIVES

Application of image-guided surgery to otology has been limited by the need for submillimeter accuracy via a fiducial system that is easily usable (noninvasive and nonobstructive).

METHODS

A dental bite-block was fitted with a rigid frame with 7 fiducial markers surrounding each external ear. The temporal bones of 3 cadaveric skulls were removed and replaced with surgical targets arranged in a bull's-eye pattern about the centroid of each temporal bone. The surgical targets were identified both within CT scans and in physical space using an infrared optical tracking system. The difference between positions in CT space versus physical space was calculated as target registration error.

RESULTS

A total of 234 independent target registration errors were calculated. Mean +/- standard deviation = 0.73 mm +/- 0.25 mm.

CONCLUSIONS

These findings show that image-guided otologic surgery with submillimeter accuracy is achievable with a minimally invasive fiducial frame. Significance In vivo validation of the system is ongoing. With such validation, this system may facilitate clinically applicable image-guided otologic surgery.

EBM RATING

A.

Preoperative imaging of chronic sinusitis by multislice computed tomography

The aim of this study was to evaluate whether multislice CT enables quality improvement and dose reduction in the imaging of the paranasal sinuses, especially when using secondary reconstructions. We compared the imaging quality of direct CT scans and secondary reconstructions of single-slice CT (SSCT) as a criterion standard with multislice CT (MSCT) of the paranasal sinuses in 80 patients suspected of having chronic sinusitis. Coronary secondary reconstructions were calculated from all transversal CT data sets. Coronary reconstructions of transversal MSCT showed a significantly better image quality compared with coronary reconstructions of SSCT. Because of the absence of dental metal artifacts, coronary reconstructions of MSCT were superior even to direct coronary images of SSCT. MSCT offered a superior examination quality compared to SSCT. A halving of radiation dosage can be reached by eliminating one examination plane.

Image-guided surgery: what is the accuracy?

PURPOSE OF REVIEW

Use of image-guided surgery (IGS) systems in otolaryngology, particularly rhinology, has grown exponentially in recent years. Central to their use is the understanding of the accuracy of each system. The purpose of this review is to discuss the error inherent in all IGS systems. A standardized technique (currently used in the engineering literature) for understanding and reporting error in IGS systems is reviewed. Using this technique, the error of commercially available IGS systems is reviewed.

RECENT FINDINGS

The most commonly used IGS systems depend on the conformation of the skin, as opposed to relying on bone-implanted devices. For these systems, mean accuracies 2 mm or less are routinely reported. This finding is independent of fiducial markers (eg, proprietary headsets, skin-affixed markers, or laser scanning of skin surfaces). Techniques of fiducial localization and registration of CT scans to intraoperative anatomy are proprietary to each company. As such, there is great variability in reporting system specifications-particularly error of IGS systems. This lack of standardization makes comparison of one system to another difficult if not impossible.

SUMMARY

Image-guided surgery systems commonly used in rhinology report mean accuracies of 2 mm or less. Surgeons must be aware that this value represents a mean of a distribution of errors. As such, 95% of the time error can be expected to be less than approximately 1.7 times its mean value. However, outliers (errors much larger and much smaller than the mean) may exist for each IGS intervention. As noted, IGS systems function to complement-not replace-knowledge of surgical anatomy.

Contemporary use of image-guided systems

Technologic advancements in radiographic imaging and interactive computers have allowed image-guided systems to be developed, which have been used to characterize surgical anatomy with greater accuracy and detail. Early generations of image-guided systems were difficult to use; however, recent modifications have allowed it to become more user friendly and less cumbersome. As a result, the application of image-guided systems has expanded and its use has become more frequent. Two major designs, optical and electromagnetic, have been used. Although most image-guided systems use computed tomography digital images, magnetic resonance image-based image-guided systems serve a unique and useful purpose. Future directions for image-guided surgery include smaller flexible instrumentation and simplified registration. As image-guided systems continue to evolve, they will enable otolaryngologist to broaden the horizon of minimally invasive techniques and operations.

Cirurgia Endoscópica Nasossinusal e da Base do Crânio Guiada por Computador

Introdução: Apesar de nas últimas décadas, as cirurgias dos seios paranasais e base de crânio terem apresentado grande progresso, principalmente com o advento dos novos instrumentais, visualização endoscópica e estudos por imagem, ainda apresentam complicações de graus variáveis. A cirurgia guiada por computador (CGC), tecnologia introduzida há poucos anos, foi idealizada para auxiliar o cirurgião na localização precisa de estruturas anatômicas durante o ato cirúrgico, proporcionando mais segurança para o paciente e para o médico. Objetivo: O objetivo deste estudo foi fazer uma avaliação global da utilidade, indicações e segurança desta tecnologia, apresentando a nossa experiência com este sistema. Forma de estudo: Clínico retrospectivo. Material e Método: Foram estudados 20 pacientes portadores de doenças nasossinusais e base de crânio, submetidos à cirurgia endoscópica dos seios paranasais e base de crânio, utilizando o sistema de navegação no período de novembro de 2000 a setembro de 2001 no Centro de Otorrinolaringologia e Fonoaudiologia de São Paulo. Dos 20 pacientes operados, onze (55%) eram do sexo feminino e 9 (45%), do sexo masculino, idades entre 16 e 74 anos, sendo a idade média de 46 anos. As avaliações da utilidade, indicações e segurança, foram baseadas em critérios subjetivos e objetivos. 1. Utilidade: foi avaliada segundo a necessidade ou não do auxílio do sistema pelo cirurgião durante as cirurgias - nenhuma, pouca, moderada, muita. 2. Indicações mais importantes: baseadas nas cirurgias ou nas áreas cirúrgicas onde o cirurgião mais necessitou do sistema. 3. Segurança: avaliada pela ocorrência ou não de complicações intra e pós-operatórias. Resultados: O sistema foi utilizado em todas as cirurgias, embora não com a mesma freqüência ou necessidade. As cirurgias que tiveram maior necessidade do sistema foram as de base de crânio, poliposes revisionais com anatomia alterada e na região do recesso frontal. Não houve nenhuma complicação intra ou pós-operatória nos pacientes operados referentes ao método empregado. Conclusão: O sistema de navegação associado à cirurgia video-endoscópica mostrou-se bastante útil e seguro nas cirurgias de base de crânio e nasossinusais, mas não essencial. O sistema se mostrou particularmente útil nas doenças do recesso e seio frontal, seio esfenoidal, doenças extensas, pacientes com alterações anatômicas, cirurgias revisionais e lesões de base de crânio.