Multislice CT-image-guided endoscopic sinus surgery using an electromagnetic tracking system

Our objective was to assess the practicability and accuracy of a computer-assisted multislice CT-guided frameless electromagnetic tracking for endoscopic sinus surgery. Eighty-two patients with various paranasal sinus diseases were evaluated. Prior to surgery, axial multislice spiral-CT scans with 2.5-mm collimation, 0.8-mm reconstruction increment, and a pitch of 3 were acquired. After Ethernet transfer of the CT data set to the guidance system, coronal and sagittal images were reconstructed. For intraoperative navigation the Insta Trak System (Visualization Technology, Boston, Mass.) was used. Navigational procedures are described in detail in the paper. Accuracy was assessed by means of visual landmarks which could be clearly identified endoscopically as well as on CT images. A second parameter for accuracy was calculated by the system itself as the root mean square (RMS). The system was able to display the position of the aspirating tip relative to anatomical structures with an average accuracy of 0.70 +/- 0.40 mm. Root mean square values showed a mean value of 0.40 +/- 0.20 mm. During surgical procedures the Insta Trak System provides the surgeon with additional image-based information to the endoscopic view. The device accuracy is high and the system proves to be practicable and efficient in ENT surgery.

[Laser-assisted transcanalicular dacryocystorhinostomy. Initial results]

BACKGROUND

Endoscopes for direct examination of the mucosa and disorders of the lacrimal drainage system have been available for four years. This had led to the wish to be able to treat lacrimal disorders by endoscopes and laser.

PATIENTS AND METHODS

Since September 1997 we have treated 48 patients by laser-assisted transcanalicular dacryocystorhinostomy (DCR) using a KTP laser, including all those with stenosis to the nasolacrimal duct and all those with postsaccal stenosis. A bony window with diameter of 5 x 5 mm was created. Bicanalicular intubation into the nose was performed and was left for 3-6 months.

RESULTS

We found 40 patients to have patent lacrimal pathway and no symptoms, 4 watering in cold weather, and 4 a restenosis.

CONCLUSIONS

The KTP-laser is sufficiently powerful to create bony windows at least 5 mm in diameter, and a transcanalicular laser-assisted DCR is therefore possible.

HLA patterns in patients with nasal polyposis

The etiology of nasal polyposis is still unknown, although risk factors include Aspirin intolerance, asthma, cystic fibrosis and primary ciliary dyskinesia. We studied frequencies of HLA A, B, DR and DQ in patients with nasal polyposis in order to determine a possible genetic component in the multifactorial pathogenesis of nasal polyps. Previous work has suggested an association of HLA-A1B8 with nasal polyposis and Aspirin intolerance. We investigated 89 patients with nasal polyposis, 11 of whom had Aspirin-intolerance, 19 asthma and 22 allergies to inhalation allergens. HLA patterns of these patients were compared to the ones of 1,070 healthy controls. No significant association of HLA-A1B8 was found with nasal polyps in the Aspirin-sensitive subgroup of our patients, but a significant association was seen with HLA-A74 and nasal polyposis.

Endolacrimal laser assisted lacrimal surgery

AIMS

To utilise the improved optical qualities of newly developed lacrimal endoscopes and newly miniaturised laser fibres for diagnostic visualisation and laser surgery of the lacrimal system.

METHODS

A KTP laser (wavelength 532 nm, 10 W energy) was used for laser assisted dacryocystorhinostomy (DCR) with endolacrimal visualisation in 26 patients. Bicanalicular silicone intubation was placed in all patients for at least 3 months.

RESULTS

After 3-9 months of follow up, the silicone tube in all 21 patients who underwent KTP laser DCR are still patent, three patients have eye watering in extremely cold weather and two required a conventional DCR.

CONCLUSIONS

The KTP laser generates enough power to open the bony window in DCR surgery. Precise endolacrimal visualisation via a specially designed miniendoscope is essential for surgical success.

[Computer assisted localization in endoscopic sinus surgery--state of the art? The Insta Trak system]

BACKGROUND

Image-guided surgery is increasingly acknowledged as useful technology also for endoscopic sinus surgery. For many years our department has been involved in the development and testing of devices for image-guided endoscopic sinus surgery. Since January 1997 we have been testing the "Insta Trak" System, which is based on electromagnetic tracking and was especially designed for use in endoscopic sinus surgery.

METHODS

We tested practicability and accuracy of the system in a wide range of cases from standard sphenoethmoidectomies to tricky frontal sinus surgery, from endoscopic tumour surgery to endoscopic repair of CSF fistulas. System accuracy was assessed by means of visual landmarks which could be clearly identified endoscopically as well as via computer screen. Additionally we measured the time for setting up the system, total operating time and rating of the subjective surgeon's assessment of the system's usefulness in each particular case.

RESULTS

We present the results according accuracy and practicability in 45 patients, who were operated on under computer-aided guidance. Our overall experience with the "Insta Trak" system was very positive. It was no longer the indeed promising, but still rather circumstantial and not always reliable technique we were used to. Operating the system was relatively easy and did not require excessive computer skills. We measured an average accuracy of 0.69 mm with a maximum deviation of 2 mm in a single test measurement. Incorrect use of the device, however, may significantly increase the possible weight of system errors.

CONCLUSIONS

The system accuracy was high and "Insta Trak" proved to be practicable and efficient in daily clinical routine. Especially in complicated cases like revision surgery "Insta Trak" proved to be extremely helpful. Whether a system like "Insta Trak" will be definitely able to lower complication rates in FESS is still an open question. Certainly in the near future no such navigational device will become a substitute for the surgeon's understanding of anatomy. In our opinion and experience "Insta Trak" is a significant development in sinus surgery. However, one must be aware of the fact that it cannot be more than yet another and indeed helpful tool.

Mucocele in an orbitoethmoidal (Haller's) cell (accidentally combined with acute contralateral dacryocystitis)

Haller's cells--according to recent terminology now called orbitoethmoidal cells (OEC)--are defined as anterior or posterior ethmoidal cells that have developed into the orbital floor. They can be excessively pneumatized and thus contribute to obstruction of the ostiomeatal complex area. We present the case of a 42 year old white male, who was admitted for treatment of an acute dacryocystitis on the right side. The CT scan revealed moderate sinusitis of the right ethmoid and maxillary sinuses and coincidentally a mucocele in an OEC on the left side. An endoscopic dacryocystorhinostomy on the right and a revision of the mucocele on the left side were performed in the same sitting. We consider both indications--stenosis of the nasolacrimal duct as well as mucoceles rewarding indications for endoscopic surgery. An external approach to the nasolacrimal duct in this case would have been problematic, as the external skin and soft tissue covering the duct already showed severe inflammatory changes. The operation of the up until that time asymptomatic mucocele was of prophylactic character. To our knowledge this is the first report of a mucocele developing in an OEC in the literature.

Cavernous haemangioma in the infraorbital nerve canal--an unusual expansion in the maxillary sinus

A patient with a four-week history of hypaesthesia and recurrent swelling of the cheek in the left infraorbital region presented with a computed tomography (CT) scan demonstrating an expansion in the infraorbital nerve canal, thought to be a neuroma. The tumour was surgically removed without complications and no bleeding. Histopathological investigation showed a partially thrombosed cavernous haemangioma. To our knowledge, after reviewing the literature, this is the first report of a cavernous haemangioma in the infraorbital nerve canal.

Endoscopic optic nerve decompression: the Graz experience

Recommendations for management of traumatic injuries to the optic nerve in the literature include expectant management, medical therapy, surgical treatment, and medical therapy combined with surgical decompression. Traditional surgical approaches to optic nerve decompression (OND) are a neurosurgical or craniotomy approach, extranasal transethmoidal approach, transorbital approach, transantral approach, and intranasal microscopic approach. Recent advances in instrumentation and surgical techniques have made an endoscopic approach to OND possible. Since 1991 endonasal endoscopic decompression of the optic nerve has been the surgical approach of choice in patients requiring OND in the authors' hospital. The endoscopic method offers many advantages over the traditional approaches. Decreased morbidity, preservation of olfaction, rapid recovery time, more acceptable cosmetic results with no external scars, no risk of injury to the developing teeth in children, and less operative stress in a patient who may have multisystem trauma are only some of the benefits associated with the endoscopic OND. The authors' technique of endonasal endoscopic approach to OND, medical management, and indications for surgery and the results in 22 patients undergoing this procedure are discussed.

[Surgical occlusion of cerebrospinal fistulas of the anterior skull base using intrathecal sodium fluorescein]

BACKGROUND

For more than 25 years, intrathecal 5% sodium fluorescein has been routinely used at the University ENT Hospital at Graz during surgical closures of CSF leaks of the anterior skull base. Especially with endoscopic approaches, this technique has been of significant help in identifying and localizing dural defects. No fluorescein-related complications occurred in the series reported.

MATERIAL AND METHODS

In a retrospective study, indications, techniques, and results of surgical closures of CSF leaks of the anterior skull base are reviewed. During 5 1/2 years from 1990-1995, 72 patients with CSF-rhinorrhea were operated on at our department, 69 of whom had sodium fluorescein applied intrathecally. In 41 patients strictly endoscopic techniques were applied, in 22 patients an external approach was chosen and in 9 cases combined approaches were used. Defects in the roof of the ethmoid, the lamina cribrosa, and in the sphenoid sinus almost exclusively were approached endoscopically. Defects in the posterior table of the frontal sinus, especially when located laterally, were approached from externally or via combined endonasal and external routes. The causes of the CSF leaks, their localization, and the surgical approaches chosen are analysed and the surgical techniques described in detail.

RESULTS

The direct coronal CT of the paranasal sinuses/anterior skull base proved to be significantly better in detecting lesions compared to axial CT images (82% vs. 53%). In all cases intrathecal fluorescein allowed for a precise localization of the defect(s). There were no fluorescein related complications in this series. In one patient with massive frontobasal chip fractures and substantial dural defect, a rhinosurgical closure was not successful. Two patients developed recurrent fistulae after several months and years respectively. One of these patients had to be operated 3 times until permanent closure was achieved. Two patients had to be revised because of mucoceles of the frontal sinuses, in both cases the initial closure of the dural defect proved to be tight.

CONCLUSION

Our results demonstrate that with exception of defects of the posterior lateral table of the frontal sinus, CSF leaks of the rhinobasis can be closed safely endoscopically. After a follow-up from 19-65 months, the overall success rate for 72 CSF leaks was at 94.5%. When applied correctly, the fluorescein technique proves to be an extremely helpful technique for diagnosis and surgery of CSF leaks.

Bilateral ventricular neurofibroma of the larynx

Laryngeal neurofibroma (LNF) is an unusual tumour and only approximately two dozen cases have been reported previously. Isolated LNF not associated with von Recklinghausen's disease is even more unusual. According to a review of the available literature, the case presented is the first bilateral one and the first originating from the ventricles. The tumour was removed completely by microlaryngoscopy without tracheostomy. The macroscopic and light macroscopic findings are presented and a review of the literature on neurogenic tumours in the larynx is presented.

Mediastinal emphysema associated with functional endoscopic sinus surgery. A case report

A case of mediastinal emphysema after functional endoscopic sinus surgery (FESS) is presented. Mediastinal emphysema is a rare and previously unreported complication after FESS. The possible aetiologies are discussed.