Endoscopic Repair of Internal Carotid Artery Injury with a Lateral Tongue Muscle Patch Graft: Novel Technique and Literature Review.

Objectives Iatrogenic injury to the internal carotid artery (ICA) is one of the most catastrophic complications of endoscopic sinus and skull base surgery. Previous research has shown that packing with a crushed muscle graft at the injury site can be an effective management technique to control bleeding and prevent the need for ICA sacrifice. Here, we describe a novel and readily available repair donor site-an autologous lateral tongue muscle patch. Design Three representative cases of a successful repair of ICA injuries using a lateral tongue muscle patch are included in this study. The graft measured approximately 2 × 3 cm and was taken from the lateral intrinsic tongue musculature. We describe the harvest of the graft, its advantages, and the details of operative repair. Results The lateral tongue provides a large and readily accessible source of muscle within the surgical field that can be quickly harvested during an endoscopic procedure. For the first case, an expanding parasellar ICA pseudoaneurysm was managed with a tongue muscle patch and nasal packing. In the second case, a cavernous ICA injury was sustained during craniopharyngioma resection. Case three involved an ICA injury during endonasal debridement of invasive fungal rhinosinusitis. None of the patients required embolization or neurovascular stenting. Postoperative angiograms and serial computed tomography angiograms showed complete resolution of the pseudoaneurysm, and the patients continued to do well at least 1 year after repair. Conclusion Lateral tongue muscle graft is an effective and efficient method to manage ICA injuries during endoscopic endonasal surgery. Advantages include the speed of harvest, donor site being readily accessible in the surgical field, and low donor site morbidity. It should be added to the repertoire of possible donor sites for addressing catastrophic sinonasal bleeding.

Balloon Sinuplasty and Stenting in the Management of Complex Frontal Sinus Outflow Tract Fractures.

OBJECTIVE: Classical management of complex fractures involving the frontal sinus outflow tract (FSOT) favors obliteration or cranialization to avoid delayed complications. We aim to exhibit success with a novel application of balloon sinuplasty and frontal stenting in the management of complex injuries disrupting the FSOT, which might have otherwise required more invasive interventions. STUDY DESIGN: Retrospective review. SETTING: Single institution, level 1 trauma center. METHODS: Retrospective review of patients presenting to a level 1 trauma center with fractures involving the FSOT. Outcomes include patency of the FSOT on imaging and endoscopy, rate of complications, degree of residual tabular displacement, and need for revision surgery. RESULTS: Twenty-five patients met inclusion criteria, with complete FSOT obstruction seen in all cases on computed tomography. All patients underwent balloon sinuplasty with frontal sinus stenting; 48% underwent concurrent anterior table repair, and 36% open repair of nasoorbitoethmoid complex fractures. The mean follow-up length was 13.9 months, at which time 91.3% of patients demonstrated radiographic and endoscopic FSOT patency. No residual sinus opacification or pneumocephalus was observed. CONCLUSION: Balloon sinuplasty with frontal sinus stenting is a straightforward and minimally invasive technique that can create a safe sinus in complex fractures disrupting the FSOT while avoiding the need for more invasive procedures.

Septal Perfoplasty for Management of Symptomatic Nasal Septal Perforation: An Alternative to Surgical Closure.

Importance: Symptomatic septal perforations are often difficult to manage and can have a significant impact on patient quality of life. Available surgical techniques for repair have demonstrated a varying rate of success, presenting a need for reliable interventions targeting symptom control. Objectives: To describe the modified surgical technique here termed septal perfoplasty. To demonstrate that creation of favorable septal perforation characteristics is effective in managing symptoms and improving patient quality of life. Design, Setting, and Participants: A retrospective review of the medical record was performed of patients who underwent the procedure of interest between July 1, 2006 and October 1, 2019 at Vanderbilt University Medical Center. All patients with symptomatic septal perforation who underwent septal perfoplasty within the timeframe reviewed were included. Septal perfoplasty was standardly performed in combination with turbinate reduction in all cases. This was combined with other indicated procedures for chronic sinusitis, repair of vestibular stenosis or nasal deformity. Main Outcomes and Measures: Creation of a well-mucosalized septal perforation, combined with patient-reported acceptable symptom control, was the primary outcome. Secondary outcomes include time to resolution, duration of follow-up, postsurgical complications, and need for further intervention. Results: Twenty patients (70% female; mean [range] age, 45.8 [15-72] years) underwent septal perfoplasty over the course of 13 years. The most common etiology of perforation was trauma (40%), presenting symptom was crusting (95%), and size of perforation repaired was large (60%). Mean follow-up was 37.6 months (range, 1-153 months). Overall, favorable perforation characteristics were created in 95% of cases by the first postoperative appointment. Acceptable symptomatic control was achieved in 18 out of 20 patients (90%), with a median time to improvement of 66 days. Eight patients required additional surgery to address chronic sinusitis or vestibular stenosis. Two patients experienced postoperative infections, treated conservatively with antibiotics. Conclusion and Relevance: Septal perfoplasty is a safe, simple, and effective method for management of symptomatic nasal septal perforation, which provides an alternative to more complicated interventions with comparable rates of symptomatic resolution. This procedure should particularly be considered for patients in which difficult repair is anticipated.

A multi-subject accuracy study on granular jamming for non-invasive attachment of fiducial markers to patients.

PURPOSE: This short communication describes experimental evaluation of a new granular jamming cap (GJC) recently introduced in Wellborn et al. (Int J Comput Assist Radiol Surg 12(6):1069-1077, 2017). The contributions beyond [8] are (1) to evaluate accuracy across multiple human subjects, and (2) to determine how much of the accuracy improvement is attributable to improved fiducial marker arrangement alone, and how much is due to granular jamming. The motivation for this GJC is to improve the accuracy of image-guidance interfaces in transnasal skull base surgery. Accuracy depends on a rigid connection between tracked fiducial markers and the patient. By molding itself to the unique contours of the individual patient's head and then solidifying, the GJC can firmly attach fiducial markers to a patient, increasing accuracy in the presence of disturbances. METHODS: A multi-subject study ([Formula: see text]) was performed to evaluate the accuracy of the GJC compared to a clinically used headband-based fixation device, in the presence of simulated accidental bumping (light force and impact events) that could occur in a real-world operating room. RESULTS: The GJC reduced the average target registration error at the pituitary gland by 66% in our force experiments and 78% in our impact experiments, which were statistically significant reductions ([Formula: see text]). Maximum target registration error was similarly reduced by 55% and 78% in the same two perturbation tests. CONCLUSION: The GJC increases the accuracy of transnasal image-guidance under force and impact perturbations by more firmly, yet non-invasively, attaching fiducial markers to the patient. We find that granular jamming provides accuracy improvement beyond that associated with improved fiducial marker arrangement.

Orbital apex syndrome caused by Alternaria species: A novel invasive fungus and new treatment paradigm.

Orbital apex syndrome as a result of invasive fungal sinusitis is a disease entity most commonly found in immunocompromised patients. Infectious invasion affecting the orbital apex can have devastating visual and life-threatening consequences. Mucormycosis and Aspergillus species are the most common causes of such infections. Alternaria fungal sinusitis is a known entity, but its ability to cause an orbital apex syndrome has not yet been reported. Here, we present a case of orbital apex syndrome in an immunocompromised patient with invasive fungal sinusitis caused by Alternaria species. The patient underwent sinus washout and placement of an intraorbital catheter for local instillation of amphotericin B for 10 days, in addition to systemic antifungal treatment, with clinical resolution of infection. The use of an intraorbital catheter for local treatment of fungal infection may offer an exenteration-sparing treatment option in these patients.

Risk Factors for Intraoperative and Postoperative Cerebrospinal Fluid Leaks in Endoscopic Transsphenoidal Sellar Surgery.

Objective To determine the factors associated with intra- and postoperative cerebrospinal fluid (CSF) leaks in setting of endoscopic transsphenoidal sellar surgery. Study Design Retrospective cohort. Setting Tertiary referral center. Subjects and Methods This study included 806 patients who underwent endoscopic transsphenoidal sellar surgery between 2004 and 2016. The associations between CSF leaks (intra- and postoperative) and patient demographics, medical history, tumor characteristics, and intraoperative repair techniques were analyzed. Results In sum, 205 (25.4%) patients had a CSF leak: 188 (23.3%) intraoperative leaks and 38 (4.7%) postoperative leaks. Twenty-one (2.6%) patients had postoperative leaks after having repair of an intraoperative leak; 55% of patients with a postoperative leak had an intraoperative leak repaired. On multivariate analysis, body mass index (BMI), hydrocephalus, suprasellar extension, and craniopharyngioma significantly predicted intraoperative CSF leaks, while only BMI and hydrocephalus predicted postoperative CSF leaks. Patients having septal flap repairs of CSF leaks had a higher postoperative leak rate relative to other repair techniques (odds ratio, 6.37; P = .013). Rigid reconstruction did not correlate with leaks. Conclusion For this large cohort of patients undergoing endoscopic transsphenoidal sellar surgery, BMI and hydrocephalus were identified as predictors of postoperative CSF leaks, including those occurring after repair of intraoperative leak. These variables may put stress on the surgical repair of sellar defects, and consideration of these risk factors may help counsel patients and guide perioperative decision making in regard to repair strategies and CSF diversion techniques.

Through the Eustachian Tube and Beyond: A New Miniature Robotic Endoscope to See Into The Middle Ear.

This paper presents a novel miniature robotic endoscope that is small enough to pass through the Eustachian tube and provide visualization of the middle ear (ME). The device features a miniature bending tip previously conceived of as a small-scale robotic wrist that has been adapted to carry and aim a small chip-tip camera and fiber optic light sources. The motivation for trans-Eustachian tube ME inspection is to provide a natural-orifice-based route to the ME that does not require cutting or lifting the eardrum, as is currently required. In this paper, we first perform an analysis of the ME anatomy and use a computational design optimization platform to derive the kinematic requirements for endoscopic inspection of the ME through the Eustachian tube. Based on these requirements, we fabricate the proposed device and use it to demonstrate the feasibility of ME inspection in an anthropomorphic model, i.e. a 3D-printed ME phantom generated from patient image data. We show that our prototype provides > 74% visibility coverage of the sinus tympani, a region of the ME crucial for diagnosis, compared to an average of only 6.9% using a straight, non-articulated endoscope through the Eustachian Tube.

The relationship between social determinants of health and utilization of tertiary rhinology care.

BACKGROUND: Chronic rhinosinusitis (CRS) has a high prevalence and significant cost and quality of life implications. Many types of practitioners care for patients with rhinosinusitis; however, patients with chronic or complicated conditions are often referred for tertiary rhinology services. It is unclear how social determinants of health affect access and utilization of these services. A better understanding of social barriers to tertiary rhinology care is needed to reduce health care disparities and improve health outcomes. The aim of the present study was to measure whether income, insurance status, race, and education affect utilization of tertiary rhinology care. METHODS: All adult patients diagnosed with CRS by rhinologists at a single tertiary care hospital were identified (2010-2014). Patient characteristics (age, gender, race, insurance status) were compared with population-level data from the hospital and from Davidson County, Tennessee, which includes Nashville. Rhinology utilization rates were calculated for each ZIP code within the county. The association between determinants of health (race, insurance status, education, median income) and tertiary rhinology utilization were measured by using multivariable regression analyses. RESULTS: A total of 1341 unique patients with CRS (median age, 50 years; 55% women, 80% white, 82% with private insurance) from Davidson County used tertiary rhinology services. These patients were significantly older and more likely to be female, white, and privately insured than patients seen hospital-wide or among the population of Davidson County (p < 0.001). Utilization rates were higher in ZIP codes with a lower proportion of minorities, a higher median income, and higher rates of private insurance and college education. However, in adjusted analysis, only attainment of a college education was independently associated with utilization of tertiary rhinology services. Utilization was 4% higher for every 1% increase in college-educated population (coefficient 0.04 [95% CI, 0.01-0.07]; p = 0.01). CONCLUSION: Results of this study indicated that some social determinants of health (race, income, educational level, insurance status) do affect utilization of tertiary rhinology services. Higher utilization among those with higher income and educational attainment are contradictory to the data, which indicated that lower socioeconomic status was associated with a higher CRS rate. Further study is required to understand the disparities in rhinology utilization rates.

Coffee: the key to safer image-guided surgery-a granular jamming cap for non-invasive, rigid fixation of fiducial markers to the patient.

PURPOSE: Accurate image guidance requires a rigid connection between tracked fiducial markers and the patient, which cannot be guaranteed by current non-invasive attachment techniques. We propose a new granular jamming approach to firmly, yet non-invasively, connect fiducials to the patient. METHODS: Our granular jamming cap surrounds the head and conforms to the contours of the patient's skull. When a vacuum is drawn, the device solidifies in a manner conceptually like a vacuum-packed bag of ground coffee, providing a rigid structure that can firmly hold fiducial markers to the patient's skull. By using the new Polaris Krios optical tracker, we can also use more fiducials in advantageous configurations to reduce registration error. RESULTS: We tested our new approach against a clinically used headband-based fiducial fixation device under perturbations that could reasonably be expected to occur in a real-world operating room. In bump testing, we found that the granular jamming cap reduced average TRE at the skull base from 2.29 to 0.56 mm and maximum TRE at the same point from 7.65 to 1.30 mm. Clinically significant TRE reductions were also observed in head repositioning and static force testing experiments. CONCLUSION: The granular jamming cap concept increases the robustness and accuracy of image-guided sinus and skull base surgery by more firmly attaching fiducial markers to the patient's skull.

Outcomes of outpatient endoscopic repair of cerebrospinal fluid rhinorrhea.

BACKGROUND: Endoscopic repair of anterior skull-base defects has become the gold standard for management of cerebrospinal fluid (CSF) rhinorrhea. Both improved techniques and adjuvant therapies have led to accepted success rates of greater than 90%. As management has evolved, shorter hospitalizations have been required and the goal of this study is to analyze the outcomes of patients repaired on an outpatient basis vs those managed as inpatients postoperatively. METHODS: Patients undergoing endoscopic repair of CSF rhinorrhea between 2004 and 2014 were identified by review of medical records. Demographic and clinical data were collected and compared between patients having surgery with and without postoperative admission. Patients managed with lumbar drains were not included. Statistical analyses were preformed to determine if any differences in patient demographics and outcomes existed. RESULTS: A total of 86 patients were identified; 39 of 86 patients (45.3%) underwent outpatient surgery; 47 patients were admitted postoperatively with a mean hospital stay of 1.66 days with a median and mode of 1 day. No statistically significant differences were found between leak location, etiology, rates of recurrence, or complications. The outpatient group was found to have a greater proportion of small defects <1 cm2 (p = 0.003). Repair technique was also significantly different between groups (p = 0.001). CONCLUSION: Endoscopic management of CSF rhinorrhea is a safe method of treatment with reliable success rates. Our retrospective analysis revealed comparable outcomes in patients treated with and without postoperative hospital admission, and supports the idea that outpatient management may be reasonable in certain patients, especially those with defects <1 cm2 .

Risk of post-operative pneumocephalus in patients with obstructive sleep apnea undergoing transsphenoidal surgery.

Patients undergoing transsphenoidal surgery (TSS) have an anterior skull base defect that limits the use of positive pressure ventilation post-operatively. Obstructive sleep apnea (OSA) can be seen in these patients and is treated with continuous positive airway pressure (CPAP). In our study we documented the incidence of pre-existing OSA and reported the incidence of diagnosed pneumocephalus and its relationship to OSA. A retrospective review was conducted from a surgical outcomes database. Electronic medical records were reviewed, with an emphasis on diagnosis of OSA and documented symptomatic pneumocephalus. A total of 324 patients underwent 349 TSS for sellar mass resection. The average body mass index of the study cohort was 32.5kg/m(2). Sixty-nine patients (21%) had documented OSA. Only 25 out of 69 (36%) had a documented post-operative CPAP plan. Out of all 349 procedures, there were two incidents of pneumocephalus diagnosed. Neither of the patients had pre-existing OSA. One in five patients in our study had pre-existing OSA. Most patients returned to CPAP use within several weeks of TSS for resection of a sellar mass. Neither of the patients with pneumocephalus had pre-existing OSA and none of the patients with early re-initiation of CPAP developed this complication. This study provides preliminary evidence that resuming CPAP early in the post-operative period might be less dangerous than previously assumed.

Outcomes of endoscopic repair of cerebrospinal fluid rhinorrhea without lumbar drains.

OBJECTIVE: Lumbar drains (LD) are commonly used during endoscopic repair of cerebrospinal fluid (CSF) rhinorrhea, either to facilitate graft healing or to monitor CSF fluid dynamics. However, the indications and necessity of LD placement remains controversial. The current study sought to evaluate endoscopic CSF leak repair outcomes in the setting of limited LD use. METHODS: Patients who underwent endoscopic repair of CSF rhinorrhea between 2004 and 2014 were identified by a review of medical records. Demographic and clinical data were extracted and compared between patients who had surgery with and patients who had surgery without a perioperative LD. A univariate analysis was performed to identify factors predictive of recurrence. RESULTS: A total of 107 patients (116 surgical procedures) were identified, with a mean follow-up of 15.8 months. Eighty-eight of 107 patients (82.2%) had surgery without an LD. The mean hospital stay was 4.48 days in the LD group versus 1.03 days in the non-LD group (p < 0.00001). There was no difference in recurrence rate between the LD and non-LD groups. Predictors of recurrence included repair technique (p = 0.04) and size of defect (p = 0.005). Body mass index, leak site (ethmoid, sphenoid, frontal), and etiology (spontaneous, iatrogenic, traumatic) were not predictive of leak recurrence. CONCLUSION: Use of LDs in endoscopic CSF leak repair was not associated with reduced recurrence rates, regardless of leak etiology, and resulted in a significant increase in hospital length of stay. Although the use of perioperative LDs to monitor CSF dynamics may have some therapeutic and diagnostic advantages, it may not be associated with clinically significant improvements in patient outcomes or recurrence rates.

REMODEL larger cohort with long-term outcomes and meta-analysis of standalone balloon dilation studies.

OBJECTIVES/HYPOTHESIS: To provide the final results from the REMODEL (randomized evaluation of maxillary antrostomy versus ostial dilation efficacy through long-term follow-up) full-study cohorts and perform meta-analyses of standalone balloon sinus dilation studies to explore long-term outcomes in a large patient sample. STUDY DESIGN: Randomized controlled trial and meta-analysis. METHODS: Final outcomes from the REMODEL randomized trial, including a larger cohort of 135 patients treated with functional endoscopic sinus surgery (FESS) or in-office balloon dilation, were evaluated. One hundred thirty patients had 12-month data, 66 had 18-month data, and 25 had 24-month data. In addition, a meta-analysis evaluated outcomes from six studies including 358 standalone balloon dilation patients with up to 24 months follow-up. RESULTS: Outcomes out to 2 years from the REMODEL full-study cohort are consistent with 6-month and 12-month outcomes. In the meta-analysis of standalone balloon dilation studies, technical success is 97.5%, and mean 20-item Sino-Nasal Outcomes Test scores are significantly and clinically improved at all time points (P < .0001). There are significant reductions (P < .0001) in work/school days missed, homebound days, physician/nurse visits, acute infections, and antibiotic prescriptions. Mean recovery time is 1.4 days. Comparison of 12-month symptom improvements and revision rates between the REMODEL FESS arm (n = 59), REMODEL balloon dilation arm (n = 71), and pooled single-arm standalone balloon dilation studies (n = 243) demonstrated no statistical difference. CONCLUSIONS: All outcomes are comparable between FESS and balloon dilation at all time points from 6 months to 24 months. Balloon dilation produces faster recovery, less postoperative pain, and fewer debridements than FESS. There is significant, durable benefit in a large series of 358 patients undergoing standalone balloon dilation.

Early Practice: External Sinus Surgery and Procedures and Complications.

External approaches to the paranasal sinuses are rarely used in the endoscopic era. However, their indications for use have not changed, and in every surgeon's career those indications may present themselves. For residents training in the endoscopic era, these procedures are also very rarely seen. In this article, the external approaches to the maxillary, ethmoid, and frontal sinuses are described: their original descriptions, modern use, and potential complications. It is hoped that this article will serve to instruct residents and practitioners alike in these techniques.

An experimental feasibility study on robotic endonasal telesurgery.

BACKGROUND: Novel robots have recently been developed specifically for endonasal surgery. They can deliver several thin, tentacle-like surgical instruments through a single nostril. Among the many potential advantages of such a robotic system is the prospect of telesurgery over long distances. OBJECTIVE: To describe a phantom pituitary tumor removal done by a surgeon in Nashville, Tennessee, controlling a robot located approximately 800 km away in Chapel Hill, North Carolina, the first remote telesurgery experiment involving tentacle-like concentric tube manipulators. METHODS: A phantom pituitary tumor removal experiment was conducted twice, once locally and once remotely, with the robotic system. Robot commands and video were transmitted across the Internet. The latency of the system was evaluated quantitatively in both local and remote cases to determine the effect of the 800-km distance between the surgeon and robot. RESULTS: We measured a control and video latency of < 100 milliseconds in the remote case. Qualitatively, the surgeon was able to carry out the experiment easily and observed no discernable difference between the remote and local cases. CONCLUSION: Telesurgery over long distances is feasible with this robotic system. In the longer term, this may enable expert skull base surgeons to help many more patients by performing surgeries remotely over long distances.

Endonasal Skull Base Tumor Removal Using Concentric Tube Continuum Robots: A Phantom Study.

Objectives The purpose of this study is to experimentally evaluate the use of concentric tube continuum robots in endonasal skull base tumor removal. This new type of surgical robot offers many advantages over existing straight and rigid surgical tools including added dexterity, the ability to scale movements, and the ability to rotate the end effector while leaving the robot fixed in space. In this study, a concentric tube continuum robot was used to remove simulated pituitary tumors from a skull phantom. Design The robot was teleoperated by experienced skull base surgeons to remove a phantom pituitary tumor within a skull. Percentage resection was measured by weight. Resection duration was timed. Setting Academic research laboratory. Main Outcome Measures Percentage removal of tumor material and procedure duration. Results Average removal percentage of 79.8 ± 5.9% and average time to complete procedure of 12.5 ± 4.1 minutes (n = 20). Conclusions The robotic system presented here for use in endonasal skull base surgery shows promise in improving the dexterity, tool motion, and end effector capabilities currently available with straight and rigid tools while remaining an effective tool for resecting the tumor.

Oral antibiotics and the management of chronic sinusitis: what do we know?

PURPOSE OF REVIEW: Chronic rhinosinusitis affected 12.5% of the general population in the United States, making it one of the most common causes for patients to seek medical care. Despite a lack of compelling evidence, antibiotics are the most frequently prescribed class of medications for the treatment of chronic sinusitis, demonstrating a deeply rooted belief that bacteria are in some way responsible for the disease. RECENT FINDINGS: Despite the high prevalence of sinusitis, the cause of chronic rhinosinusitis remains elusive despite multiple attempts to determine the underlying cause. Theories have come and gone throughout the years with fungi, bacteria, host immunological defects, allergy, structural and functional defects, gastroesophageal reflux disease, environmental chemicals, and bacterial biofilms being blamed for this chronic inflammatory state of the sinonasal mucosa. Recent literature has continued to explore these various theories. SUMMARY: To date, there is no high-quality evidence that antibiotic therapy has any effect on the long-term management of chronic rhinosinusitis. No randomized placebo-controlled studies evaluating the utility of antibiotics have as yet been conducted. There remains an urgent need for a high-quality, prospective clinical trial to determine the proper role of antibiotics in the treatment of chronic rhinosinusitis.

Robotic surgery for the sinuses and skull base: what are the possibilities and what are the obstacles?

PURPOSE OF REVIEW: Robotic surgery in otolaryngology - head and neck surgery has become a valuable tool in certain anatomic approaches; however, its application in surgery of the paranasal sinuses and anterior skull base is still in an investigatory phase and requires further evaluation. RECENT FINDINGS: Existing robotic surgical systems face particular limitations in their application at the skull base because of instrument size and lack of variability. Unfortunately, only one system is available commercially that is applicable in the head and neck region and FDA approved for use in patients. This system, although advantageous in many otolaryngologic procedures, is difficult to use for endoscopic sinus and skull base surgery. However, other systems that target this anatomic subsite specifically are in development and show promise. Advances in the design of robotic arms, materials, and shape will potentially give surgeons a significant advantage over traditional endoscopic techniques. SUMMARY: This article will review the current applications of robotic systems in paranasal sinus and skull base surgery, describe the requirements of a robotic system for use in this type of surgery, and describe a system under development at our institution.

A Telerobotic System for Transnasal Surgery.

Mechanics-based models of concentric tube continuum robots have recently achieved a level of sophistication that makes it possible to begin to apply these robots to a variety of real-world clinical scenarios. Endonasal skull base surgery is one such application, where their small diameter and tentacle like dexterity are particularly advantageous. In this paper we provide the medical motivation for an endonasal surgical robot featuring concentric tube manipulators, and describe our model-based design and teleoperation methods, as well as a complete system incorporating image-guidance. Experimental demonstrations using a laparoscopic training task, a cadaver reachability study, and a phantom tumor resection experiment illustrate that both novice and expert users can effectively teleoperate the system, and that skull base surgeons can use the robot to achieve their objectives in a realistic surgical scenario.

Forces Applied at the Skull Base during Transnasal Endoscopic Transsphenoidal Pituitary Tumor Excision.

Objectives Our laboratory is developing a surgical robotic system to further improve dexterity and visualization that will allow for broader application of transnasal skull base surgery. To optimize this system, intraoperative force data are required. Using a modified curette, force data were recorded and analyzed during pituitary tumor excision. Design A neurosurgical curette was modified by the addition of a force sensor. The instrument was validated in an in vitro model to measure forces during simulated pituitary tumor excision. Following this, intraoperative force data from three patients during transnasal endoscopic excision of pituitary tumors was obtained. Setting Academic medical center. Main Outcome Measures Forces applied at the skull base during surgical excision of pituitary tumors. Results Average forces applied during in vitro testing ranged from 0.1 to 0.15 N. Average forces recorded during in vivo testing ranged from 0.1 to 0.5 N. Maximal forces occurred with collisions of the bony sella. The average maximal force was 1.61 N. There were no complications related to the use of the modified curette. Conclusions Forces to remove pituitary tumor are small and are similar between patients. The in vitro model presented here is adequate for further testing of a robotic skull base surgery system.