[In vitro study on signal transduction in mice spiral ganglion cell stimulated by multi-wavelength laser based on calcium imaging]

Objective: To research the auditory nerve transduction effects under multi-wavelength pulsed laser stimulations within a safe and acceptable signal range. Methods: The real-time detection of intracellular calcium concentration was adopted by specific fluorescent indicator staining based on calcium imager. The spiral ganglion cells of mice were cultured in vitro. After fluorescent indicating, morphologic observation under optical microscope, Fura-2 calcium ion fluorescence excitation, intact morphology cells selection, fixing the optical fiber, the spiral ganglion cells were irradiated by different wavelength laser, including visible light (450 nm) and near infrared light (808 nm,1 065 nm). The intracellular calcium concentration was monitored by calcium ion imaging. Results: When 450 nm laser stimulated spiral ganglion cells, the intracellular calcium concentration was strongly increased, however, for other wavelength laser stimulation, there was no obvious relative response. And the sensitivity expression of the nerve cells under laser was related with the location of laser fiber. Cells closer to the fiber produced more obvious changes in calcium ion concentration, while for cells farther away from the fiber, the change amplitudes were weaker although the number of changes in calcium ion concentration was consistent. Conclusion: The spiral ganglion cells of mice can induce a signal transduction response under the action of laser, and the response has laser wavelength selectivity.

[Evaluation of the electrode position by CBCT following cochlear implantation]

Objective: To observe the position of the electrode in the cochlea following cochlear implantation by cone beam computed tomography (CBCT). Methods: Twenty-five children who received cochlear implantation and CBCT examinations in the Department of Otorhinolaryngology Head and Neck Surgery from the Second Hospital of Shandong University between January 2016 and December 2017 were selected. There were 15 males (17 ears) and 10 females (10 ears). The age ranged from 0.5 to 7.0 years old, with a median age of 1.6 years. 23 patients with unilateral implantation and two patients with bilateral implantation. The implants were all Med-El standard 12-electrode contact arrays. The CBCT was used to determine the position of the electrode in the cochlea, the distance between the electrode contacts and modiolus, and intracochlear insertion length of the electrode arrays. SPSS Statistics, version 22.0 was used for data processing and statistical analysis. Results: CBCT images could clearly demonstrate the structure of round window, oval window, modiolus, osseous cochlear duct, osseous spiral lamina, and electrodes. The electrode arrays of all the children were fully implanted into the cochlea. 26 of the electrode arrays were located in the scala tympani and one of them was inserted into the scala vestibular. The mean intracochlear insertion length of the electrode arrays was 30.23 (95%CI, 30.04-30.71) mm. The distance between the electrode contacts and modiolus gradually increased at the 1-4th electrode contacts and reached the maximum at the 4th electrode contacts with an average of 1.10 mm (95%CI, 1.02 to 1.18 mm), and then gradually decreased from the 5th electrode contacts. Conclusions: CBCT can clearly show cochlear fine structures and therefore accurately assess the electrode position following cochlear implantation.