Sinonasal and ear manifestations of Erdheim-Chester disease.

To calculate the prevalence of sinonasal and ear involvement in an Erdheim-Chester disease (ECD) population, to describe the different ear, nose and throat (ENT) manifestations and to study the association between ENT involvement, other organ involvement, and BRAF mutations. We led a retrospective monocentric study in the national referral center for ECD. One hundred and sixty-two patients with ECD and ENT data were included between January 1, 1980 and December 31, 2020. Ear and nose clinical and radiological findings were noted. We described and studied the prevalence of ENT involvement in ECD population. The association between sinonasal and ear involvement, other organ involvement, and BRAF mutations was calculated. The prevalence of ENT manifestations is around 45%. No clinical rhinologic or otologic signs were specific to ECD. Sinus imaging was abnormal in 70% of cases. A bilateral maxillary sinus frame osteosclerosis was highly specific of ECD. Associations were found between the sinus MRI imaging type and BRAF status, central nervous system involvement, cerebellum involvement and xanthelasma. Sinonasal or ear involvement is frequent in ECD and has specific imaging features for sinuses. Trial registration: #2011-A00447-34.

An Optimized Robot-Based Technique for Cochlear Implantation to Reduce Array Insertion Trauma.

OBJECTIVE: To compare the intracochlear trauma induced by optimized robot-based and manual techniques with a straight electrode array prototype inserted at different lengths. STUDY DESIGN: Experimental study. SETTING: Robot-based otologic surgery laboratory. SUBJECTS AND METHODS: A prototype array was inserted at different insertion lengths (21 and 25 mm) in 20 temporal bones. The manual insertion was performed with a microforceps. The optimized approach consisted of an optimal axis insertion provided by a robot-based arm controlled by a tracking system, with a constant speed of insertion (0.25 mm/s) achieved by a motorized insertion tool. The electrode position was determined at the level of each electrode by stereomicroscopic cochlea section analysis. RESULTS: A higher number of electrodes correctly located in the scala tympani was associated with the optimized approach ( P = .03, 2-way analysis of variance). Regardless of the insertion technique used, the array inserted at 25 mm allowed complete insertion of the active stimulating portion of the array in all cases. Insertion depth was greater when the array was inserted to 25 mm versus 21 mm ( P < .001, 2-way analysis of variance). The optimized insertion was associated with less trauma than that from manual insertion regardless the length of the inserted array ( P = .04, 2-way analysis of variance). CONCLUSION: Compared with a manual insertion, intracochlear trauma could be reduced with array insertion performed on an optimal axis by using motorized insertion and by applying a constant insertion speed.

Cochlear Implant Insertion Axis Into the Basal Turn: A Critical Factor in Electrode Array Translocation.

HYPOTHESIS: An inappropriate insertion axis leads to intracochlear trauma during cochlear implantation (CI). BACKGROUND: Few studies assessed the relationship between the insertion axis and the electrode scalar location. METHODS: Preimplantation cone-beam CT (CBCT) was performed on 12 human temporal bones. In five temporal bones, an optimal insertion axis was planned, due to the impossibility to attain the ST centerline from the posterior tympanotomy, because of facial canal position. In the seven other temporal bones, an inaccurate insertion axis was intentionally planned (optimal axis+15 degrees). Automated CI array insertion according to the planned axis was performed with a motorized insertion tool driven by a navigated robot-based arm. The cochlea and basilar membrane were segmented from the preimplantation CBCT and the array segmented from the postimplantation CBCT to construct a merged final three-dimensional (3D) model. Microscopical and 3D analysis were performed to determine the intracochlear trauma at the level of each electrode. RESULTS: A good agreement was observed in determining electrode position between microscopic analysis and the 3D model (Cohen's kappa k = 0.67). The angle of approach to the ST centerline was associated with the number of electrodes inserted into the ST (r = -0.65, p = 0.02, [95% CI -0.90 to -0.11] Spearman's rank correlation). CONCLUSION: A 3D reconstruction model was effective in determining the array position in the cochlea scalae. Our data indicate that the angle of approach to the ST centerline is a critical factor in intracochlear trauma. Additional studies should be conducted to assess the importance of the insertion axis with other array designs.

Influence of electrode array stiffness and diameter on hearing in cochlear implanted guinea pig.

During cochlear implantation, electrode array translocation and trauma should be avoided to preserve residual hearing. The aim of our study was to evaluate the effect of physical parameters of the array on residual hearing and cochlear structures during insertion. Three array prototypes with different stiffnesses or external diameters were implanted in normal hearing guinea pigs via a motorized insertion tool carried on a robot-based arm, and insertion forces were recorded. Array prototypes 0.4 and 0.4R had 0.4 mm external diameter and prototype 0.3 had 0.3 mm external diameter. The axial stiffness was set to 1 for the 0.4 prototype and the stiffnesses of the 0.4R and 0.3 prototypes were calculated from this as 6.8 and 0.8 (relative units), respectively. Hearing was assessed preoperatively by the auditory brainstem response (ABR), and then at day 7 and day 30 post-implantation. A study of the macroscopic anatomy was performed on cochleae harvested at day 30 to examine the scala location of the array. At day 7, guinea pigs implanted with the 0.4R array had significantly poorer hearing results than those implanted with the 0.3 array (26±17.7, 44±23.4, 33±20.5 dB, n = 7, vs 5±8.7, 1±11.6, 12±11.5 dB, n = 6, mean±SEM, respectively, at 8, 16 and 24 kHz, p<0.01) or those implanted with the 0.4 array (44±23.4 dB, n = 7, vs 28±21.7 dB, n = 7, at 16 kHz, p<0.05). Hearing remained stable from day 7 to day 30. The maximal peak of insertion force was higher with the 0.4R array than with the 0.3 array (56±23.8 mN, n = 7, vs 26±8.7 mN, n = 6). Observation of the cochleae showed that an incorrectly positioned electrode array or fibrosis were associated with hearing loss ≥40 dB (at 16 kHz). An optimal position in the scala tympani with a flexible and thin array and prevention of fibrosis should be the primary objectives to preserve hearing during cochlear implantation.