Sebastian P. Schraven

Prevalence and histopathology of chronic polypoid sinusitis in pediatric patients with cystic fibrosis

BACKGROUND Chronic sinusitis is almost invariably a feature of cystic fibrosis. However, data on the endoscopically confirmed prevalence of chronic polypoid sinusitis (CPS) and its histological features are limited. METHODS Single centre prospective observational study. Unselected pediatric CF patients (n=81; ≤ 18 years) were endoscopically assessed for the prevalence of CPS. Sixteen of these underwent sinus surgery. The surgically obtained sinus specimens were compared to sinus specimen of non-CF-patients undergoing sinus surgery (n=61), using conventional histology and immunohistochemistry. RESULTS The prevalence of endoscopically confirmed CPS increased with age from 19% in infants younger than six years reaching 45% in adolescents. In CF patients, histology typically showed dilated glandular ducts and a predominance of mucous glands. The number of plasma cells and mast cells but not of eosinophils was significantly elevated compared to non-CF patients. CONCLUSION Prevalence of CPS in pediatric CF patients increases with age. Our findings indicate that chronic bacterial infection rather than allergic mechanisms may forward this pathology.

Conditions for highly efficient and reproducible round-window stimulation in humans.

Round-window stimulation is a new clinical approach for the application of active middle-ear implants. To investigate factors influencing the efficiency of round-window stimulation, experiments in 6 human temporal bones were performed with different actuator geometries and coupling conditions. The experiments show that the amplitude ratio between stapes and round-window actuator vibration is most efficient when using a 1.0-mm diameter rod with a 30° inclined tip geometry and an attached silicone pad. In this case, the amplitude ratio is 0.34 for frequencies up to 1.5 kHz and 0.27 for frequencies up to 20 kHz, with a standard deviation of only 4–6 dB at most frequencies. The analysis of data presented here and in a companion paper suggests that control of proper round-window membrane pretension as well as the inclined tip geometry are the major requirements for maximal performance.

Alternative Fixation of an Active Middle Ear Implant at the Short Incus Process

Introduction: Since 1996, the preferred approach for positioning the active middle-ear implant Vibrant Soundbridge© is a mastoidectomy and a posterior tympanotomy. With this device, placement of the floating mass transducer (FMT) on the long incus process is the standard method for treatment of mild-to-severe sensorineural hearing loss in the case of normal middle-ear anatomy. The aim of this study was to determine the vibrational effectiveness of FMT placement at the short incus process. Materials and Methods: An extended antrotomy and a posterior tympanotomy were performed in 5 fresh human temporal bones. As a control for normal middle-ear function, the tympanic membrane was stimulated acoustically and the vibration of the stapes footplate and the round-window (RW) membrane were (sequentially) measured by laser Doppler vibrometry. Vibration responses for coupling of an FMT to the long incus process (standard coupling) were compared to those for coupling to the short incus process. Results: Apart from narrow frequency bands near 3 and 9 kHz for the stapes footplate and RW membrane, respectively, the velocity responses presented no significant differences between standard coupling of the FMT and coupling to the short incus process. Conclusion: Coupling the FMT to the short incus process may be a viable alternative in cases where the surgical approach is limited to an extended antrotomy. A reliable technique for attachment to the short incus process has yet to be developed.

Standardized Active Middle-Ear Implant Coupling to the Short Incus Process.

Introduction Active middle-ear implants with floating-mass transducer (FMT) technology are used to treat mild-to-severe sensorineural hearing losses. The standard surgical approach for incus vibroplasty is a mastoidectomy and a posterior tympanotomy, crimping the FMT to the long incus process. An alternative fixation side with less surgical trauma might be the short incus process and incus body. The aim of this study was to develop and test a short incus process coupling device for its functional properties in temporal bone preparations and clinical practice. Materials and Methods An extended antrotomy and a posterior tympanotomy were performed in 10 fresh human temporal bones. As a control for normal middle-ear function, the tympanic membrane was stimulated acoustically, and the vibration of the stapes footplate was measured using laser Doppler vibrometry. FMT-induced vibration responses of the stapes were then measured for standard attachment at the long process and for 2 types of couplers designed for attachment at the short process of the incus (SP1 and SP2 coupler). Additionally, the functional outcome in 2 patients provided with an SP2 coupler was assessed postoperatively at 2 weeks, 3 months, and then 11 months, using pure-tone audiometry, auditory thresholds for frequency-modulated (warble) tones, vibroplasty thresholds, and speech audiometry in quiet and noise. Results For the SP2 coupler, velocity-amplitude responses in temporal-bone preparations showed generally similar mean amplitudes as compared with the standard coupling of the FMT to the long process but with clearly increased mean amplitudes between 0.7 and 1.5 kHz and with reduced interindividual variation between 0.5 and 3 kHz. The clinical data of 2 patients with mild-to-severe sensory hearing loss showed good vibroplasty thresholds and convincing results for speech audiometry in quiet (Freiburger monosyllables at 65 dB SPL, 23 ± 31% unaided versus 83 ± 4% aided) and noise (Hochmair-Schulz-Moser-test at 65 dB SPL at 10 dB SNR, 32 ± 45% unaided and 42 ± 29% aided). Conclusion The attachment of the FMT to the short incus process with the SP2 coupler leads to good mechanical and functional coupling in an experimental setup and clinical practice.

Concept and evaluation of an endaurally insertable middle-ear implant

A concept for a partially implantable hearing device, for which the power supply and signal transmission are provided by an optical transmission path, is evaluated. The actuator is designed to fit into the round-window niche and to couple directly to the round-window membrane. Implantable hearing aids can be a suitable solution in the case of severe hearing loss, where conventional hearing aids often fail. However, the surgical effort for an implantation is comparatively high. Therefore, the objective of our work was to provide a hearing system which combines reliable coupling to the auditory system with an easy implantation technique. The actuator was designed as a piezoelectric thin-film cantilever. The optical transmission path was realised using an infrared light-emitting diode combined with an active receiver circuit. For a voltage of 1V, the unloaded actuator presents displacement amplitudes of 1μm up to a stimulus frequency of 25kHz and forces up to 0.2mN. Proportionally larger forces can be achieved by stacking single actuators. The overall transmission loss from the electrical input of the light-emitting diode driver to the mechanical output of the unloaded actuator was less than 25dB at 1kHz and maximum output.

Long-term Stability of the Active Middle-ear Implant with Floating-mass Transducer Technology: A Single-center Study.

Objective: To examine the long-term results of an active middle-ear implant (AMEI) with floating-mass transducer (FMT) technology. Study Design: Prospective cohort study of German-speaking patients implanted with an AMEI between 2006 and 2013. Setting: Single-center study. Patients: Eighty-three patients. Intervention: AMEI with FMT technology implantation. Main Outcome Measures: Long-term outcome (27 mo; range, 12–84 mo) for FMT position in correlation with pure-tone audiometry, auditory thresholds for frequency-modulated (warble) tones, vibroplasty thresholds for pure tones, and speech audiometry in quiet and noise. Results: In 15.6% of patients, a revision surgery was necessary to improve functional performance of the AMEI, and the highest revision rate was found with FMT coupling to the round window not using couplers. A peak number of revision surgeries were observed 3 years after the initial surgery. Stable audiological results (pure-tone audiometry and speech audiometry in quiet and noise) were observed up to 84-month post-surgery. Incus vibroplasty (classic indication) showed a significantly lower functional gain compared with oval and round window vibroplasty. Vibroplasty in combined or conductive hearing loss showed no functional difference between forward and reverse stimulation of the cochlea; however, significantly lower vibroplasty thresholds were detected when using a coupler. Conclusions: The AMEI with FMT technology can be safely used in treatment of patients with mild-to-severe sensorineural, conductive, or mixed hearing loss. Optimized coupling, especially in incus vibroplasty, has to be developed to achieve enhanced audiological results.

BDNF in Lower Brain Parts Modifies Auditory Fiber Activity to Gain Fidelity but Increases the Risk for Generation of Central Noise After Injury

For all sensory organs, the establishment of spatial and temporal cortical resolution is assumed to be initiated by the first sensory experience and a BDNF-dependent increase in intracortical inhibition. To address the potential of cortical BDNF for sound processing, we used mice with a conditional deletion of BDNF in which Cre expression was under the control of the Pax2 or TrkC promoter. BDNF deletion profiles between these mice differ in the organ of Corti (BDNFPax2-KO) versus the auditory cortex and hippocampus (BDNFTrkC-KO). We demonstrate that BDNFPax2-KO but not BDNFTrkC-KO mice exhibit reduced sound-evoked suprathreshold ABR waves at the level of the auditory nerve (wave I) and inferior colliculus (IC) (wave IV), indicating that BDNF in lower brain regions but not in the auditory cortex improves sound sensitivity during hearing onset. Extracellular recording of IC neurons of BDNFPax2 mutant mice revealed that the reduced sensitivity of auditory fibers in these mice went hand in hand with elevated thresholds, reduced dynamic range, prolonged latency, and increased inhibitory strength in IC neurons. Reduced parvalbumin-positive contacts were found in the ascending auditory circuit, including the auditory cortex and hippocampus of BDNFPax2-KO, but not of BDNFTrkC-KO mice. Also, BDNFPax2-WT but not BDNFPax2-KO mice did lose basal inhibitory strength in IC neurons after acoustic trauma. These findings suggest that BDNF in the lower parts of the auditory system drives auditory fidelity along the entire ascending pathway up to the cortex by increasing inhibitory strength in behaviorally relevant frequency regions. Fidelity and inhibitory strength can be lost following auditory nerve injury leading to diminished sensory outcome and increased central noise.

Reinforced active middle ear implant fixation in incus vibroplasty.

Objectives: The active middle ear implant Vibrant Soundbridge® was originally designed to treat mild-to-severe sensorineural hearing losses. The floating mass transducer (FMT) is crimped onto the long incus process. The procedure is termed incus vibroplasty to distinguish from other attachment sites or stimulus modi for treating conductive and mixed hearing losses. Rare but possible complications are difficult incus anatomy, necrosis of the long incus process, secondary detachment, and loosening of the FMT with concomitant amplification loss. The aim of this study was to functionally evaluate reinforcement of the standard attachment of the FMT to the long incus process. The head of a Soft CliP® stapes prosthesis was used for reinforcement. Functional evaluation was performed in temporal-bone preparations and in clinical practice. Design: A subtotal mastoidectomy and a posterior tympanotomy were performed in ten fresh human temporal bones. As a control for normal middle-ear function, the tympanic membrane was stimulated acoustically and the vibration of the stapes footplate and the round-window (RW) membrane, respectively, were measured by laser Doppler vibrometer (LDV). FMT-induced vibration responses of the stapes and RW were then measured for standard attachment and attachment reinforced with the head of a Soft CliP® stapes prosthesis. Additionally, the outcome in two groups of patients with incus vibroplasty using standard and the reinforced FMT attachment were compared. Eleven patients were treated by standard coupling; nine patients obtained reinforcement with the head of the Soft CliP® stapes prosthesis. Three to six months postoperatively, auditory thresholds for frequency-modulated (warble) tones and vibroplasty thresholds for pure tones were measured. Results: In temporal bone, laser Doppler vibrometer measurements showed significantly enhanced vibration amplitudes of the stapes footplate and the RW membrane for the reinforced attachment compared with those for the standard attachment (on average, 5–10 dB at frequencies below 1 kHz and above 4 kHz). Interindividual amplitude variations were also smaller for reinforced attachment (on average, the standard deviation was 4–7 dB smaller). The clinical data showed lower vibroplasty thresholds for reinforced attachment compared with standard attachment, which amounted to, on average, 16 dB at 500 Hz and 12 dB at 4 kHz. Conclusion: Auxiliary fixation of the FMT by reinforcing the attachment to the long incus process, in these experiments with the head of a Soft CliP® stapes prosthesis, leads to enhanced mechanical and functional coupling, evidenced by lower vibroplasty thresholds and increased bandwidth together with reduced variability of the vibrational frequency responses of the stapes footplate and RW membrane.

Vibro-EAS: a proposal for electroacoustic stimulation.

Hypothesis In situ evaluation of the vibration performance of a hybrid system for intracochlear fluid stimulation, constructed from a floating mass transducer (FMT) coupled to an electric acoustic stimulation (EAS) cochlea implant (CI) electrode. Background EAS uses both CI technology to restore severe-to-profound hearing loss at high frequencies and acoustic amplification for mild-to-moderate hearing loss in the low-to-mid frequency range. More patients with residual hearing are becoming candidates for EAS surgery because of the improved techniques for hearing preservation. Most patients with partial deafness fulfill the audiological criteria at low and mid-frequencies for the active middle-ear implant with FMT (VSB). The FMT of the VSB is a potential device for acoustical stimulation in EAS. Methods In seven fresh human temporal bones, stapes amplitude responses for fixation of a FMT to the long incus process (standard coupling) was compared with those for FMT fixation to a 20-mm inserted standard cochlea electrode array (31.5 mm) via the round window (Vibro-EAS). Vibration of the stapes footplate was measured by laser Doppler vibrometry. Results For 0.316 Vrms drive voltage, stimulation of the intracochlear fluid using a FMT-driven CI electrode (Vibro-EAS) yielded stapes amplitude responses comparable to those for acoustic stimulation with 84 dB SPL. These amplitude responses are 30 to 42 dB lower at frequencies up to 4 kHz than those for VSB standard coupling. Conclusion Intracochlear combined electrical and mechanical stimulation may be a viable technique for electroacoustic stimulation. A reliable technique for attachment or integration of the FMT to the cochlea electrode array has yet to be developed.

Dendritic cell tumor in a salivary gland lymph node: a rare differential diagnosis of salivary gland neoplasms

Dendritic cell tumors are extremely rare neoplasms arising from antigen-presenting cells of the immune system. We report a case of a 69-year-old man with an unremarkable medical history who presented with a 2-months history of a gradually enlarging painless, firm, mobile, 2 × 2-cm swelling at the caudal pole of the left parotid gland without systemic symptoms. Histologically, the tumor consisted of a spindle cell proliferation in an intraparotideal lymph node. Based on the histopathologic, immunohistochemical and electron microscopic findings, a dendritic cell tumor, not otherwise specified (NOS) in an intraparotideal lymph node was diagnosed.The patient underwent complete tumor resection, and is currently free of disease, 2 years after surgery. These extremely rare tumors must be distinguished from other more common tumors in the salivary glands. Awareness that dendritic cell tumors may occur in this localization, careful histologic evaluation and ancillary immunohistochemical and electron microscopical analyses should allow for recognition of this entity.Virtual SlidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1614859498581601.