Pre-surgery planning tool for estimation of resection volume to improve nasal breathing based on lattice Boltzmann fluid flow simulations.

PURPOSE: State-of-the-art medical examination techniques (e.g., rhinomanometry and endoscopy) do not always lead to satisfactory postoperative outcome. A fully automatized optimization tool based on patient computer tomography (CT) data to calculate local pressure gradient regions to reshape pathological nasal cavity geometry is proposed. METHODS: Five anonymous pre- and postoperative CT datasets with nasal septum deviations were used to simulate the airflow through the nasal cavity with lattice Boltzmann (LB) simulations. Pressure gradient regions were detected by a streamline analysis. After shape optimization, the volumetric difference between the two shapes of the nasal cavity yields the estimated resection volume. RESULTS: At LB rhinomanometry boundary conditions (bilateral flow rate of 600 ml/s), the preliminary study shows a critical pressure gradient of -1.1 Pa/mm as optimization criterion. The maximum coronal airflow ΔA  := cross-section ratio [Formula: see text] found close to the nostrils is 1.15. For the patients a pressure drop ratio ΔΠ  := (pre-surgery - virtual surgery)/(pre-surgery - post-surgery) between nostril and nasopharynx of 1.25, 1.72, -1.85, 0.79 and 1.02 is calculated. CONCLUSIONS: LB fluid mechanics optimization of the nasal cavity can yield results similar to surgery for air-flow cross section and pressure drop between nostril and nasopharynx. The optimization is numerically stable in all five cases of the presented study. A limitation of this study is that anatomical constraints (e.g. mucosa) have not been considered.

Nasal cavity airflow: Comparing laser doppler anemometry and computational fluid dynamic simulations.

Objective parameters to assess the physical flow conditions of breathing are scarce and decisions for surgery, e.g. nasal septum correction, mainly rely on subjective surgeon judgment. To define decision supporting parameters, we compare laser Doppler anemometry (LDA) and numerical computational fluid dynamic simulations (CFD) of the airflow velocity vector fields in the nasal cavity, including lattice Boltzmann (LB) and finite volume methods (FVM). The simulations are based on an anonymous patient CT dataset with septal deviation. LDA measurements are preformed using a 3D printed model. Nasal airflow geometry is randomly deformed in order to approximate surgical changes. The root-mean-square velocity error near the nasal valve of laser Doppler anemometry and lattice Boltzmann simulations is 0.071. Changes in geometry similarly affect both measurement and simulation.

Intractable Posterior Epistaxis due to a Spontaneous Low-Flow Carotid-Cavernous Sinus Fistula: A Case Report and a Review of the Literature.

We report a case of a 90-year-old patient with intractable posterior epistaxis presenting as the only symptom of a nontraumatic low-flow carotid-cavernous sinus fistula. Purpose of this case report is to introduce low-flow carotid-cavernous sinus fistula in the differential diagnosis of intractable posterior epistaxis. We provide a literature review for the sequence of actions for the confrontation of posterior epistaxis. We also emphasize the significance of the radiological diagnostic and therapeutic procedures in the management of posterior epistaxis due to pathology of the cavernous sinus. The gold-standard diagnostic procedure of carotid-cavernous sinus fistula is digital subtraction angiography (DSA). DSA with coils is also the state-of-the-art therapy. By failure of DSA, neurosurgery or stereotactic radiosurgery (SRS) may be used as alternatives. SRS may also be used as enhancement procedure of the DSA. Considering the prognosis of a successfully closed carotid-cavernous sinus fistula, recanalization occurs only in a minority of patients. Close follow-up is advised.

No association between obesity and post-tonsillectomy haemorrhage.

BACKGROUND: The prevalence of overweight and obesity is increasing worldwide. The impact of overweight on post-tonsillectomy haemorrhage rates in children and adults is unclear. METHODS: Body mass index and post-tonsillectomy haemorrhage were evaluated in all patients treated with tonsillectomy within one year in a tertiary referral centre. Bleeding episodes were categorised according to the Austrian Tonsil Study. RESULTS: Between June 2011 and June 2012, 300 adults and children underwent tonsillectomy. Post-tonsillectomy haemorrhage occurred in 55 patients. Of those, 29 were type A (history of blood in saliva only, no active bleeding), 15 were type B (active bleeding, treatment under local anaesthesia) and 11 were type C (active bleeding, treatment under general anaesthesia). The return to operating theatre rate was 3.7 per cent. Post-tonsillectomy haemorrhage was more frequent in adolescents and adults than in children. Overweight or obesity was positively correlated with age. Post-tonsillectomy bleeding was recorded in 11.1 per cent of underweight patients, 18.9 per cent of normal weight patients and 18.7 per cent of overweight patients (p = 0.7). Data stratification (according to age and weight) did not alter the post-tonsillectomy bleeding risk (p = 0.8). CONCLUSION: Overweight or obesity did not increase the risk of post-tonsillectomy haemorrhage in either children or adults.

Medium-level laser in chronic tinnitus treatment.

The purpose of this study was to evaluate the effect of medium-level laser therapy in chronic tinnitus treatment. In a prospective double-blind placebo-controlled trial, either active laser (450 mW, 830 nm combined Ga-Al-As diode laser) or placebo irradiation was applied through the external acoustic meatus of the affected ear towards the cochlea. Fourty-eight patients with chronic tinnitus were studied. The main outcome was measured using the Goebel tinnitus questionnaire, visual analogue scales measuring the perceived loudness of tinnitus, the annoyance associated with tinnitus, and the degree of attention paid to tinnitus as well as psycho-acoustical matches of tinnitus pitch and loudness. The results did show only very moderate temporary improvement of tinnitus. Moreover, no statistically relevant differences between laser and placebo group could be found. We conclude that medium-level laser therapy cannot be regarded as an effective treatment of chronic tinnitus in our therapy regime considering the limited number of patients included in our study.

[Acute rhinosinusitis in adults--EPOS 2012 Part II]. / Akute Rhinosinusitis bei Erwachsenen--EPOS 2012 Teil II.

Rhinosinusitis (RS) is an inflammatory disorder of the mucous membranes of the nose and paranasal sinuses, which are almost always affected concurrently. The EPOS2012 position paper initiated by the European Rhinologic Society and the European Academy of Allergy and Clinical Immunology is a recent comprehensive source on this common disease affecting approximately 20% of the population worldwide. Inflammation, not infection, is considered the cornerstone of RS, which is considered a temporal and pathophysiologic disease continuum with various subtypes. Acute rhinosinusitis is diagnosed, if typical symptoms last less than 12 weeks. It affects approximately 10% of the European population. Acute RS is further subdivided into acute viral, acute postviral and acute bacterial RS. Acute viral RS lasts less than 10 days with decreasing symptom intensity, while acute postviral RS is characterized by longer duration or a sudden increase of symptom severity around the 5th day ('double sickening'). Acute bacterial RS is assumed if 3 of the following 5 criteria are additionally met: Discoloured discharge (with unilateral predominance), severe local pain (with unilateral predominance), fever (>38ºC), elevated ESR/CRP, and 'double-sickening'. For the treatment of acute viral RS, nasal saline irrigations and OTC cold remedies are advised. In acute postviral RS, additional topical steroids are suggested. Advantages and disadvantages of antibiotic treatment in acute bacterial RS are detailed. Overall, the new EPOS position paper infers a reorientation in this area of high medical, pharmaceutical and economic relevance.

Quantitative error analysis for computer assisted navigation: a feasibility study.

PURPOSE: The benefit of computer-assisted navigation depends on the registration process, at which patient features are correlated to some preoperative imagery. The operator-induced uncertainty in localizing patient features-the user localization error (ULE)-is unknown and most likely dominating the application accuracy. This initial feasibility study aims at providing first data for ULE with a research navigation system. METHODS: Active optical navigation was done in CT-images of a plastic skull, an anatomic specimen (both with implanted fiducials), and a volunteer with anatomical landmarks exclusively. Each object was registered ten times with 3, 5, 7, and 9 registration points. Measurements were taken at 10 (anatomic specimen and volunteer) and 11 targets (plastic skull). The active NDI Polaris system was used under ideal working conditions (tracking accuracy 0.23 mm root-mean-square, RMS; probe tip calibration was 0.18 mm RMS). Variances of tracking along the principal directions were measured as 0.18 mm(2), 0.32 mm(2), and 0.42 mm(2). ULE was calculated from predicted application accuracy with isotropic and anisotropic models and from experimental variances, respectively. RESULTS: The ULE was determined from the variances as 0.45 mm (plastic skull), 0.60 mm (anatomic specimen), and 4.96 mm (volunteer). The predicted application accuracy did not yield consistent values for the ULE. CONCLUSIONS: Quantitative data of application accuracy could be tested against prediction models with iso- and anisotropic noise models and revealed some discrepancies. This could potentially be due to the facts that navigation and one prediction model wrongly assume isotropic noise (tracking is anisotropic), while the anisotropic noise prediction model assumes an anisotropic registration strategy (registration is isotropic in typical navigation systems). The ULE data are presumably the first quantitative values for the precision of localizing anatomical landmarks and implanted fiducials. Submillimetric localization is possible for implanted screws; anatomic landmarks are not suitable for high-precision clinical navigation.

Substantial dose reduction in modern multi-slice spiral computed tomography (MSCT)-guided craniofacial and skull base surgery.

PURPOSE: Reduction of the radiation exposure involved in image-guided craniofacial and skull base surgery is an important goal. The purpose was to evaluate the influence of low-dose protocols in modern multi-slice spiral computed tomography (MSCT) on target registration errors (TREs). MATERIALS AND METHODS: An anthropomorphic skull phantom with target markers at the craniofacial bone and the anterior skull base was scanned in Sensation Open (40-slice), LightSpeed VCT (64-slice) and Definition Flash (128-slice). Identical baseline protocols (BP) at 120  kV/100  mAs were compared to the following low-dose protocols (LD) in care dose/dose modulation: (LD-I) 100  kV/35ref. mAs, (LD-II) 80  kV/40 - 41ref. mAs, and (LD-III) 80  kV/15 - 17ref. mAs. CTDIvol and DLP were obtained. TREs using an optical navigation system were calculated for all scanners and protocols. Results were statistically analyzed in SPSS and compared for significant differences (p ≤ 0.05). RESULTS: CTDIvol for the Sensation Open/LightSpeed VCT/Definition Flash showed: (BP) 22.24 /32.48 /14.32 mGy; (LD-I) 4.61 /3.52 /1.62 mGy; (LD-II) 3.15 /2.01 /0.87 mGy; and (LD-III) na/0.76 /0.76 mGy. Differences between the BfS (Bundesamt für Strahlenschutz) reference CTDIvol of 9 mGy and the lowest CTDIvol were approximately 3-fold for Sensation Open, and 12-fold for the LightSpeed VCT and Definition Flash. A total of 33 registrations and 297 TRE measurements were performed. In all MSCT scanners, the TREs did not significantly differ between the low-dose and the baseline protocols. CONCLUSION: Low-dose protocols in modern MSCT provided substantial dose reductions without significant influence on TRE and should be strongly considered in image-guided surgery.

Optical and electromagnetic tracking for navigated surgery of the sinuses and frontal skull base.

BACKGROUND: New hardware and software algorithms in electromagnetic tracking for computer assisted surgery (CAS) have been developed. We aimed to compare electromagnetic tracking for navigated procedures in frontal skull base surgery to optical tracking. METHODS: Target registration error (TRE) was determined in 6 anatomic specimens in an experimental wet-lab. As targets, 6 titanium screws were evenly distributed over the surgical areas of interest from the frontal sinus to the clivus. Optical tracking and electromagnetic tracking was evaluated in identical software environment using a last generation commercially available navigation system. RESULTS: Submillimetric application accuracy could be achieved with both tracking modalities. Optical was more accurate than electromagnetic tracking and its reliability was better. Target position did not influence TRE, however TRE varied significantly from skull to skull. CONCLUSIONS: Although less accurate than optical tracking, electromagnetic tracking still offers excellent accuracy and reliability for anterior skull base surgery. Electromagnetic tracking is not dependent on direct line of sight between its hardware components and therefore easily integrated even in cluttered operating theatres.

[The learning curve of registration in navigated skull base surgery]. / Lernkurve bei der Registrierung navigierter Eingriffe an der Schädelbasis.

BACKGROUND: Computer aided surgery (CAS) is advantageous in challenging procedures in head and neck surgery. It is not clear, if the application of CAS has to be trained to achieve reliable results. The learning curve of the registration of the patient's coordinates to prior acquired radiologic imagery was investigated. MATERIAL AND METHODS: 4 residents performed pair-point registrations on 5 anatomic specimens in an experimental wet lab. The residents were in the same year of education and had no experience in CAS procedures. After each registration the application error was evaluated by determining the target registration error (TRE). Pair point matching by skin glued external fiducials was compared with pair point matching by internal anatomical landmarks. RESULTS: The application accuracy was improved by increasing numbers of performed registrations (p<0.001, trendtest of Page). An inverse trend of the learning curve could be observed, the median TRE values improved from 3.3 mm in the first registration to 1.6 mm after the fifth registration. In comparison e. g. an experienced CAS-user can achieve submillimetric TRE values under wet lab conditions. Pair point matching by anatomical landmarks resulted in worse application accuracy initially and the learning curve was steeper than with external fiducial markers. CONCLUSION: There is a training effect in CAS interventions. Pair point matching results in sufficient application accuracy after training only.

[Automatic registration of patients with A-mode ultrasound for computer-assisted surgery. Laboratory proof of concept]. / Automatische Registration des Patienten mit A-Mode-Ultraschall für computerunterstützte Chirurgie. Funktionsnachweis im Labor.

BACKGROUND: The main source of error in 3D navigation is the patient-to-image registration process. Anatomical landmarks or adhesive markers perform sub-optimally. Bone-anchored invasive markers significantly change the clinical workflow of navigated ENT surgery, are invasive and cause patient discomfort. In order to minimize registration errors and to further streamline the clinical use of intraoperative 3D navigation we demonstrate that A-mode ultrasound allows an accurate 3D surface profile of the os occipitale to be created which can be reliably registered on preoperative patient CT data. METHODS: The transducer is mechanically positioned with sub-millimeter accuracy on the patient's occiput. From the sound echos a 3D surface is generated and registered to the preoperative CT images with the iterative closest point (ICP) algorithm. The evaluation of our setup was performed on three anatomic specimens and one bony skull. RESULTS: The ultrasound echoes from the occiput allowed the creation of an adequate 3D surface which could be registered to a segmentation of the CT image with an accuracy greater than 1.5 mm. The experiments were evaluated by an intuitive representation of the spatial deviation between CT and ultrasound data as a color-coded map. CONCLUSION: The approach to scan the posterior skull with A-mode ultrasound enables automatic intraoperative registration and can be integrated into the intraoperative setup.

External nasal valve collapse - a case-control and interventional study employing a novel internal nasal dilator (Nasanita).

BACKGROUND: Nasal alar collapse is a common problem and difficult to assess and treat. METHODS: In 10 healthy controls and 10 patients with alar collapse, the size of the external nasal valve was analyzed on standardized nasal base photographs during quiet breathing and forced inspiration. A novel internal nasal dilator (Nasanita, Siemens & Co, Germany) was employed to assess the effects of a therapeutic intervention. In addition, active anterior rhinomanometry was performed. RESULTS: During quiet breathing, the external nasal valves were significantly smaller in patients with alar collapse (0.3 +/- 0.08 cm2) than in controls (0.7 +/- 0.2 cm2; p < 0.001). In heal-thy controls, forced inspiration did not significantly alter the size of the external nasal valve (-1.8% +/- 27.5%; p = 0.84), whereas it significantly decreased the external valve area in patients with alar collapse (-42.1% +/- 26.4%; p = 0.001). The internal nasal dilator significantly increased external valve areas during quiet breathing and forced inspiration and completely abolished alar collapse. Nasal airflow at a transnasal pressure difference of 150 Pa was not correlated with external valve size. Nasal airflow increased significantly after inserting the internal nasal dilator to 1300 +/- 370 ml/s (p < 0.001) in controls and 1300 +/-300 ml/s (p < 0.01) in patients. CONCLUSION: A small sized external nasal valve appears to be a major causative factor of alar collapse. A novel internal nasal dilator effectively enlarged the external nasal valve, abolished alar collapse and improved nasal airflow.

[3-D navigation in the petrous bone with submillimeter accuracy]. / Submillimetrische 3D-Navigation im Felsenbein. Eine Laboruntersuchung.

BACKGROUND: In order to evaluate the possible submillimeter application accuracy in computer-aided navigation in the petrous bone, we performed a set of approximately 3,000 measurements on a specially prepared anatomic specimen using the Zeiss STN intraoperative navigation system. This allowed direct measurements of relevant anatomic structures in and around the petrous bone which are usually not directly accessible. RESULTS: We found that the best results can be achieved by exploiting contemporary multislice CT-imaging with 0.5 mm slice thickness and by direct radiologic imaging of the petrous bone; additionally, an extrinsic marker structure, the VBH-referencing element, served as an extension of the applied surface markers for the "patient-to-image" referencing procedure. Interestingly, the additional use of a surface registration, as provided by the STN-navigation system, to potentially optimize the registration, did not improve the results. In the best case, i.e. with high-resolution CT-imaging, 0.5 mm slice spacing, the use of surface markers, and the extrinsic referencing structure applied, an absolute difference between the calculated and actual position of the probe was 0.42+/-0.69 mm. CONCLUSIONS: These results show that intraoperative 3-D navigation can be successfully transferred to a clinical application in the petrous bone or at the cerebellopontine angle with satisfactory accuracy in this highly sensitive anatomic region, even if only a restricted area of the patient can be used for the referencing procedure.

Intraspecific variation in serum proteins of brown hare (Lepus europaeus Pallas, 1778).

1. Serum proteins of brown hare (Lepus europaeus Pallas, 1778) were studied by the use of 1D PAGE, 2D agarose-PAGE, immunoblotting, inhibitions of trypsin and chymotrypsin, and specific staining for esterase. 2. Some serum proteins were identified, and easily interpretable polymorphisms were found in transferrin alpha 1B glycoprotein, protease inhibitors ATC2, ATC3 and AT1, esterase ES1 and in an unidentified postalbumin PO. 3. On the basis of family studies the evidence was obtained that the variants observed in these polymorphic proteins are under genetic control by codominant alleles of autosomal loci.