Thomas Beleites

Morphology of bony tissues and implants uncovered by high-resolution tomographic imaging

Abstract Synchrotron radiation-based micro computed tomography contributes to the increasing demand for uncovering non-destructively the microscopic morphology of bony tissues and their interface regions with implants using isotropic spatial resolution in three-dimensional space. Using the microscopic ring structure of otoliths, the coherence-related interplay between density resolution and spatial resolution is demonstrated. The monochromatised, highly intense synchrotron radiation allows analysis of the morphology of arthritic joints without significant beam-hardening artefacts in a quantitative manner. It further enables intensity-based segmentation of metallic implants within bone and thereby to quantitatively study the bone morphology around different kinds of middle and inner ear implants. This knowledge permits improving medical interventions and optimising the implants design with respect to surface modification, mechanical properties, and shape.

Experience with vibroplasty couplers at the stapes head and footplate.

Objective To report on experiences with implanting the Vibrant Soundbridge (VSB) coupled to the stapes head using a new Clip-Coupler or to the stapes footplate using a new OW-Coupler (CliP- or OW-Coupler Vibroplasty). Study Design Single subject, repeated measures. Setting Two university hospital ENT departments. Patients Fourteen German-speaking patients from 2 European study sites were implanted with either a CliP-Coupler or OW-Coupler attached to a VSB floating mass transducer (FMT). They were evaluated preoperatively and postoperatively for bone and air conduction thresholds with and without the implant, as well as speech perception tests. Main Outcome Measures Measuring the efficacy and safety of OW- and CliP-Coupler-Vibroplasty as a method to treat mixed hearing loss. Results Bone conduction thresholds remained stable preoperatively and postoperatively. The patients’ average speech perception performances at 65/80 dB (HL) increased from 0.8/13.8% to 63/82%. The pure tone audiograms showed an average improvement in air conduction thresholds after implantation with the VSB of 25 dB at 0.5 kHz to 50 dB at 4 kHz. Conclusion OW- or Clip-Coupler-Vibroplasty using couplers was found to be a straightforward procedure, which produced good results in this group of patients.

Objektive Messung der normalen Nasalanz im sächsischen Sprachraum

ZusammenfassungIn den USA wurde von Fletcher das Nasometer als objektive Nasalitätsmessmethode entwickelt. Für das Nasometer bestehen im deutschsprachigen Raum für vergleichbare Testmaterialien keine anerkannten Normwerte. Anliegen der vorliegenden Studie ist die Untersuchung der auditiv normalen Nasalität im sächsischen Sprachraum mit Hilfe des Nasometers.Es wurden die Nasalanzwerte von 51 gesunden Testpersonen mit auditiv normaler Nasalität aus dem sächsischen Sprachraum mit dem Nasometer (Modell 6200, Fa. Kay-Elemetrics, USA) bestimmt. Als Testmaterialien wurden die Vokale “a”, “e”, “i”, “o”, “u”, die Sätze “Die Schokolade ist sehr lecker” und “Nenne meine Mama Mimi”, sowie die Texte “Nordwind und Sonne”, “Ein Kindergeburtstag” und ein Auszug aus dem Text “Der große Gesang” von Strittmatter benutzt.Der Mittelwert der Nasalanz für den keine Nasallaute enthaltenden Satz liegt bei 13,0%, für Vokale bei 17,7%. Der mittlere Nasalanzwert beträgt für den viele Nasale enthaltenden Prüfsatz 67,2%. Der Mittelwert der Texte liegt bei 33–41%. Die Ergebnisse für die Texte stimmen gut mit den Ergebnissen von Reuter aus dem brandenburgischen Sprachraum überein.Als Normwert für die normale Nasalanz im deutschsprachigen Raum wird für gemischte Texte der Bereich von 20–55% vorgeschlagen.AbstractIn the United States of America, the nasometer was developed by Fletcher as an objective method for measuring nasality. There are no accepted normal values for comparable test materials regarding the German language. The aim of this study was the examination of the auditively normal nasality of Saxon-speaking people with the nasometer.The nasalance of 51 healthy Saxon-speaking test persons with auditively normal nasality was measured with a model 6200 nasometer (Kay-Elemetrics, U.S.A.). The text materials used were the vowels “a”, “e”, “i”, “o”, and “u”, the sentences “Die Schokolade ist sehr lecker” (“The chocolate is very tasty”) and “Nenne meine Mama Mimi” (“Name my mama Mimi”), and the texts of “North wind and sun”, “A childrens birthday”, and an arbitrary selection from Strittmatter.The mean nasalance for the vowels was 17.7%, for the sentence containing no nasal sounds 13.0%, and for the sentence containing many nasal sounds 67.2%. The mean value of the texts was 33–41%. The results for the texts agreed well with the results of Reuter (1997), who examined people from the state of Brandenburg.A range from 20% to 55% is suggested as the normal value for nasalance in the German-speaking area.

Osseointegration of Titanium Prostheses on the Stapes Footplate

The success of middle ear reconstructive surgery depends on stable coupling between the prosthesis and residual ossicles. To establish a stable fixed point on the stapes footplate for subsequent prosthesis reconstruction, a titanium footplate anchor was coated with osteoinductive substances to induce a controlled osseointegration on the footplate. Various studies have shown that collagen-based matrices with and without bone growth and differentiation factors can induce and enhance bone formation and consequently increase implant stability. The ears of 23 one-year-old Merino sheep (n = 46) were divided into five groups and implanted with a specially designed footplate anchor. The surface of each implant was modified by applying a collagenous matrix (collagen I or II) either with immobilized bone morphogenic protein (BMP-4) or transforming growth factor-ß, respectively, to stimulate osteoblastic activation and differentiation on the stapes footplate with subsequent osseointegration. Polychrome labeling was used to assess new bone formation and remodeling during the study. After study termination on day 84, synchrotron radiation-based computed microtomography and histomorphometry were used to identify bone implant contact. Eight implants showed radiographical and/or histological evidence of integration by newly formed bone. An osseointegration could histologically be proven in two of these eight specimens, and additional ectopic bone formations were seen in another 21 specimens. In all animals, bone turnover on the footplate was proven by polychrome labeling. This study proves the general ability to induce a controlled osseointegration of titanium implants biologically activated with artificial extracellular matrices on their surfaces on the stapes footplate in a mammalian organism.

Clinical investigation of flat panel CT following middle ear reconstruction: a study of 107 patients

ObjectivesAfter middle ear reconstruction using partial or total ossicular replacement prostheses (PORP/TORP), an air–bone gap (ABG) may persist because of prosthesis displacement or malposition. So far, CT of the temporal bone has played the main role in the diagnosis of reasons for postoperative insufficient ABG improvement. Recent experimental and clinical studies have evaluated flat panel CT (fpCT) as an alternative imaging technique that provides images with high isovolumetric resolution, fewer metal-induced artefacts and lower irradiation doses.MethodsOne hundred and seven consecutive patients with chronic otitis media with or without cholesteatoma underwent reconstruction by PORP (n = 52) or TORP (n = 55). All subjects underwent preoperative and postoperative audiometric testing and postoperative fpCT.ResultsStatistical evaluation of all 107 patients as well as the sole sub-assembly groups (PORP or TORP) showed a highly significant correlation between hearing improvement and fpCT-determined prosthesis position. FpCT enables detailed postoperative information on patients with middle ear reconstruction.ConclusionsFpCT is a new imaging technique that provides immediate feedback on surgical results after reconstructive middle ear surgery. Specific parameters evaluated by fpCT may serve as a predictive tool for estimated postoperative hearing improvement. Therefore this imaging technique is suitable for postoperative quality control in reconstructive middle ear surgery.Key Points• Flat panel CT offers advantages with regard to artefacts and radiation dose.• FpCT provides higher isovolumetric resolution of temporal bone and middle ear implants.• FpCT allows prediction of the postoperative hearing outcome in patients.• FpCT is an important tool for immediate postoperative quality control.• FpCT improves postoperative management of patients with complications following ossicular replacement

Impact of partial mastoid obliteration on caloric vestibular function in canal wall down mastoidectomy.

Objective: To evaluate the influence of our technique of partial mastoid obliteration with autologous bone pâté covered by cartilage plates on vestibular stimulation. Methods: Twenty-six patients who were treated for recurrent chronic otitis media by revision canal wall down tympanomastoidectomy and subsequent partial obliteration were invited for follow-up; 18 patients agreed to a complete follow-up including vestibular testing. Patients received questionnaires for evaluating preoperative and postoperative symptoms associated with vertigo. Examination comprised otomicroscopy, pure-tone audiometry, and caloric testing. Results: Mean follow-up was 6 years. Before surgery, 54% of the patients reported vertigo on caloric stimuli such as wind, water, or suction cleaning of the tympanomastoid cavity. In all patients, these symptoms were suspended after partial mastoid obliteration. The postoperative obliterated cavity volume averaged 3.1 ml. All cavities after surgery appeared completely epithelialized and dry. The postoperative caloric vestibular tests revealed an average nystagmus count of 46 beats per minute compared with 72 beats before surgery. Thus, the partial mastoid cavity obliteration led to a mean nystagmus reduction of 36% in our study group. Conclusion: Our technique of partially obliterating tympanomastoid cavities with autologous bone pâté being covered by cartilage plates results in small cavities with complete epithelialization of all surfaces. Furthermore, obliteration of mastoid cavities confers protection to the labyrinthine organ, thereby reducing postoperative vertigo on caloric stimulation.

Cholesteatoma recidivism: comparison of three different surgical techniques.

Objective To compare cholesteatoma recidivism rates after exclusive transcanal technique (ETC), combined transcanal and mastoidal technique (TCM, both subsets of intact canal wall technique, ICW), and canal wall down surgery (CWD). Study Design Retrospective case review and clinical case study Setting Tertiary referral center. Patients 406 cholesteatoma surgeries (2007–2009), 116 ears in clinical re-examination at least 1 year postoperatively. Intervention Sequential cholesteatoma surgery with ETC, TCM, or CWD. Main Outcome Measures Cholesteatoma recidivism, residual and recurrent disease, localization of recidivism, validity of clinical findings. Results Out of 406 patients, ETC was performed in 227 (56%), TCM in 122 (30%), and CWD in 57 (14%) cases. Recidivism rates after ICW (15%) and CWD (16%) were almost similar. Recidivism was more frequent after ETC (11%) than after TCM (25%). Residuals were observed in 2% after ETC, 6.5% after TCM, and 7% after CWD. Incidence of recurrent disease was 9% for ETC, 18% for TCM, and 9% for CWD. Preferred localization of recidivism was the tympanic cavity after ETC (92%) and CWD (56%) and the mastoid cavity after TCM (53%). The clinical re-examination showed no further recidivistic disease. Conclusions Sequential surgery is an effective and successful strategy in cholesteatoma eradication, providing a similar recidivism rate compared to following cholesteatoma retrograde and resection of the posterior canal wall. Lower recidivism after ETC was observed as a consequence of limited disease and the postoperative middle ear status determined the higher rate of recurrence after TCM. Therefore, the restricted visualization of the middle ear during ICW surgery does not increase the rate of recidivism, compared with CWD, as described in other studies. Cholesteatoma recidivism is mainly attributed to the surgeon’s experience that outweighs the chosen strategy.

Morphological and Radiologic Evaluation of the Human Nasopalatine Duct

In several mammals, a direct connection between the nasal cavity and the oral cavity is a common finding. The structure is named the nasopalatine duct (NPD). It has been hypothesized to be functional in terms of transportation of odorants from the oral cavity to the nasal cavity. In humans, the NPD exists during embryological development. The connection between the nasopalatine infundibulum and the incisive fossa is typically closed at the time of birth. We present the case of a 24-year-old man who presented with a persistent NPD. By means of a thin, soft tube, it was possible to probe the NPD. Magnetic resonance imaging revealed a bony gap between the hard palate and the alveolar process of the maxillary bone with a length of 16 mm and a width of 6 mm. In light of the literature of the past 500 years, this represents a rare finding of a persistent NPD.

New total ossicular replacement prostheses with a resilient joint: experimental data from human temporal bones.

Hypothesis New flexible total ossicular prostheses with an integrated microjoint can compensate for large static displacements in the reconstructed ossicular chain. When properly designed, they can mimic the function of the joints of the intact chain and ensure good vibration transfer in both straight and bent conditions. Background Prosthesis dislocations and extrusions are frequently observed after middle ear surgery. They are mainly related to the altered distance between the coupling points because of large static eardrum displacements. Methods The new prostheses consist of 2 titanium shafts, which are incorporated into a silicone body. The sound transfer function and stapes footplate displacement at static loads were evaluated in human temporal bones after ossicular reconstruction using prostheses with 2 different silicones with different hardness values. The stiffness and bending characteristics of the prostheses were investigated with a quasi-static load. Results The sound transfer properties of the middle ears with the prostheses inserted under uncompressed conditions were comparable with those of ears with intact ossicular chains. The implant with the soft silicone had improved acoustic transfer characteristics over the implant with the hard silicone in a compressed state. In the quasi-static experiments, the minimum medial footplate displacement was found with the same implant. The bending characteristics depended on the silicone stiffness and correlated closely with the point and angle of the load incidence. Conclusion The titanium prostheses with a resilient joint that were investigated in this study had good sound transfer characteristics under optimal conditions as well as in a compressed state. As a result of joint bending, the implants compensate for the small changes in length of the ossicular chain that occur under varying middle ear pressure. The implants require a stable support at the stapes footplate to function properly.

Sound Transfer of Active Middle Ear Implants

Implantable hearing aids are gaining importance for the treatment of sensorineural hearing loss and also for mixed hearing loss. The various hearing aid systems, combined with different middle ear situations, give rise to a wide range of different reconstructions. This article attempts to summarize the current knowledge concerning the mechanical interaction between active middle ear implants (AMEIs) and the normal or reconstructed middle ear. Some basic characteristics of the different AMEIs are provided in conjunction with the middle ear mechanics. The interaction of AMEIs and middle ear and the influence of various boundary conditions are discussed in more detail.