scholarly journals Tubular manipulators: a new concept for intracochlear positioning of an auditory prosthesis

2015 ◽  
Vol 1 (1) ◽  
pp. 515-518 ◽  
Author(s):  
Thomas S. Rau ◽  
Josephine Granna ◽  
Thomas Lenarz ◽  
Omid Majdani ◽  
Jessica Burgner-Kahrs
Keyword(s):  
Inner Ear ◽  
Preliminary Investigation ◽  
Electrode Array ◽  
Maximum Error ◽  
Patient Specific ◽  
Final Position ◽  
Auditory Prosthesis ◽  
Scala Tympani ◽  
Potential Applicability ◽  
Torsion Stiffness

AbstractThe aim of this study was to investigate the applicability of tubular manipulators as an actuator mechanism for intracochlear positioning of the electrode array (EA) of a cochlear implant (CI). This is motivated by the vision of an atraumatic insertion of the EA into the inner ear (cochlea) without any damage to the intracochlear structures in combination with a well-defined final position. To realize this, an actuator mechanism is required which allows consideration of the patient-specific anatomy. We propose a tubular manipulator for this task. It consists of three concentric tubes: A straight outer tube serves as a guiding sleeve to enter the inner ear (cochlea) and two additional telescoping, superelastic, helically precurved tubes. By selecting helical tube parameters of both tubes prior insertion, a patient-specific curling behaviour of the tubular manipulator can be achieved. For preliminary investigation, segmentation and skeletonization of 5 human scala tympani were performed to determine their centrelines. These centrelines were considered as individual ideal insertion paths. An optimization algorithm was developed to identify suitable tube set parameters (curvature, diameter, length, torsion, stiffness) as well as configuration parameters (translation and rotation of the 2 inner tubes). Different error values describing the deviation of the shape of the tubes with respect to the insertion path were used to quantify the optimization results. In all cases tube set parameters for a final position within the cochlea were found, while keeping the maximum error below 1mm. These preliminary results are promising in terms of the potential applicability of tubular manipulators for positioning auditory prosthesis inside the scala tympani of the inner ear.

Na and nonelectrolyte entry into inner ear fluids of the rat

1987 ◽  
Vol 253 (1) ◽  
pp. F50-F58 ◽  
Author(s):  
O. Sterkers ◽  
E. Ferrary ◽  
G. Saumon ◽  
C. Amiel
Keyword(s):  
Cerebrospinal Fluid ◽  
Inner Ear ◽  
Lateral Ventricle ◽  
Endothelial Barrier ◽  
Scala Tympani ◽  
Epithelial Secretion ◽  
Kinetics Of ◽  
Hydrophilic Solutes ◽  
Inner Ear Fluids ◽  
Scala Vestibuli

Kinetics of hydrophilic solute entry into endolymph (EL), perilymph (PL), and cerebrospinal fluid (CSF) were studied after intravenous administration (sodium, urea, glycerol, mannitol, sucrose) and cerebral lateral ventricle injection (urea, sucrose) of tracers in anesthetized rats. Samples of cochlear EL, PL of scala vestibuli (PLV), PL of scala tympani (PLT), and cisternal CSF were obtained. The data showed slow entry of tracers in PLV, PLT, and CSF as follows: Na greater than urea greater than mannitol approximately sucrose; slower entry of mannitol and sucrose in PLT and CSF than in PLV; 1 h delayed peak of radioactivity in PLV compared with the immediate peaks in PLT and CSF after CSF injection, and the value of PLV peak was 13% that in CSF; extremely slow entry of nonelectrolytes in EL. These results indicate that PLV originates mainly from plasma across a blood-perilymph barrier that restricts the entry of small hydrophilic solutes. The blood-perilymph barrier is most likely composed of an endothelial barrier associated with an epithelial secretion. The latter could be located at the vasculo-epithelial zone of the spiral limbus.

scholarly journals The Panoramic ECAP Method: estimating patient-specific patterns of current spread and neural health in cochlear implant users

2020 ◽  
Author(s):  
Charlotte Garcia ◽  
Tobias Goehring ◽  
Stefano Cosentino ◽  
Richard E Turner ◽  
John M. Deeks ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Electrode Array ◽  
Significant Negative Correlation ◽  
Patient Specific ◽  
Clinical Settings ◽  
Neural Activation ◽  
Activation Patterns ◽  
Current Spread ◽  
Compound Action Potentials ◽  
In Cis

The knowledge of patient-specific neural excitation patterns from cochlear implants can provide important information for optimising efficacy and improving speech perception outcomes. The Panoramic ECAP (or ‘PECAP’) method (Cosentino, et al., 2015) uses forward-masked electrically evoked compound action potentials (ECAPs) to estimate neural activation patterns of cochlear implant (CI) stimulation. The algorithm requires ECAPs be measured for loudness-balanced stimuli from all combinations of probe and masker electrodes, and takes advantage of ECAP amplitudes being a result of the overlapping excitatory areas of both probes and maskers. Here we present an improved version of the PECAP algorithm that imposes biologically realistic constraints on the solution and produces separate estimates of current spread and neural health along the length of the electrode array. The algorithm was evaluated for reliability and accuracy in three ways: (1) computer-simulated current-spread and neural-health scenarios, (2) comparisons to psychophysical correlates of neural health and electrode-modiolus distances in human CI users, and (3) detection of simulated neural ‘dead’ regions (using forward masking) in human CI users. The PECAP algorithm reliably estimated the computer simulated scenarios. A moderate but significant negative correlation between focused thresholds and PECAP’s neural health estimates was found, consistent with previous literature. It also correctly identified simulated dead regions in seven CI users. The revised PECAP algorithm provides an estimate of the electrode-to-neuron interface in CIs that could be used to inform and optimize CI stimulation strategies for individual patients in clinical settings.

Connectivity-based thalamus parcellation and surgical targeting of somatosensory subnuclei

2021 ◽  
pp. 1-8
Author(s):  
Ashley L. B. Raghu ◽  
Sean C. Martin ◽  
Tariq Parker ◽  
Tipu Z. Aziz ◽  
Alexander L. Green
Keyword(s):  
Electrode Array ◽  
Leg Pain ◽  
Patient Specific ◽  
Chronic Neuropathic Pain ◽  
Arm Pain ◽  
Face Pain ◽  
Pain Patients ◽  
And Diffusion ◽  
Term Benefit

OBJECTIVE The anatomy of the posterolateral thalamus varies substantially between individuals, presenting a challenge for surgical targeting. Patient-specific, connectivity-based parcellation of the thalamus may effectively approximate the ventrocaudal nucleus (Vc). This remains to be robustly validated or assessed as a method to guide surgical targeting. The authors assessed the validity of connectivity-based parcellation for targeting the Vc and its potential for improving clinical outcomes of pain surgery. METHODS A cohort of 19 patients with regional, chronic neuropathic pain underwent preoperative structural and diffusion MRI, then progressed to deep brain stimulation targeting the Vc based on traditional atlas coordinates. Surgical thalami were retrospectively segmented and then parcellated based on tractography estimates of thalamocortical connectivity. The location of each patient’s electrode array was analyzed with respect to their primary somatosensory cortex (S1) parcel and compared across patients with reference to the thalamic homunculus. RESULTS Ten patients achieved long-term pain relief. Sixty-one percent of an average array (interquartile range 42%–74%) was located in the S1 parcel. In patients who achieved long-term benefit from surgery, array location in the individually generated S1 parcels was medial for face pain, centromedial for arm pain, and centrolateral for leg pain. Patients who did not benefit from surgery did not follow this pattern. Standard stereotactic coordinates of electrode locations diverged from this pattern. CONCLUSIONS Connectivity-based parcellation of the thalamus appears to be a reliable method for segmenting the Vc. Identifying the Vc in this way, and targeting mediolaterally as appropriate for the region of pain, merits exploration in an effort to increase the yield of successful surgical procedures.

Electrical Cochlear Stimulation in the Deaf Cat: Comparisons Between Psychophysical and Central Auditory Neuronal Thresholds

2000 ◽  
Vol 83 (4) ◽  
pp. 2145-2162 ◽  
Author(s):  
Ralph E. Beitel ◽  
Russell L. Snyder ◽  
Christoph E. Schreiner ◽  
Marcia W. Raggio ◽  
Patricia A. Leake
Keyword(s):  
Electrical Stimulation ◽  
Auditory System ◽  
Pulse Rate ◽  
Auditory Nerve ◽  
Round Window ◽  
Electrode Array ◽  
Scala Tympani ◽  
Behavioral Thresholds ◽  
Current Pulses ◽  
Stimulation Of

Cochlear prostheses for electrical stimulation of the auditory nerve (“electrical hearing”) can provide auditory capacity for profoundly deaf adults and children, including in many cases a restored ability to perceive speech without visual cues. A fundamental challenge in auditory neuroscience is to understand the neural and perceptual mechanisms that make rehabilitation of hearing possible in these deaf humans. We have developed a feline behavioral model that allows us to study behavioral and physiological variables in the same deaf animals. Cats deafened by injection of ototoxic antibiotics were implanted with either a monopolar round window electrode or a multichannel scala tympani electrode array. To evaluate the effects of perceptually significant electrical stimulation of the auditory nerve on the central auditory system, an animal was trained to avoid a mild electrocutaneous shock when biphasic current pulses (0.2 ms/phase) were delivered to its implanted cochlea. Psychophysical detection thresholds and electrical auditory brain stem response (EABR) thresholds were estimated in each cat. At the conclusion of behavioral testing, acute physiological experiments were conducted, and threshold responses were recorded for single neurons and multineuronal clusters in the central nucleus of the inferior colliculus (ICC) and the primary auditory cortex (A1). Behavioral and neurophysiological thresholds were evaluated with reference to cochlear histopathology in the same deaf cats. The results of the present study include: 1) in the cats implanted with a scala tympani electrode array, the lowest ICC and A1 neural thresholds were virtually identical to the behavioral thresholds for intracochlear bipolar stimulation; 2) behavioral thresholds were lower than ICC and A1 neural thresholds in each of the cats implanted with a monopolar round window electrode; 3) EABR thresholds were higher than behavioral thresholds in all of the cats (mean difference = 6.5 dB); and 4) the cumulative number of action potentials for a sample of ICC neurons increased monotonically as a function of the amplitude and the number of stimulating biphasic pulses. This physiological result suggests that the output from the ICC may be integrated spatially across neurons and temporally integrated across pulses when the auditory nerve array is stimulated with a train of biphasic current pulses. Because behavioral thresholds were lower and reaction times were faster at a pulse rate of 30 pps compared with a pulse rate of 2 pps, spatial-temporal integration in the central auditory system was presumably reflected in psychophysical performance.

scholarly journals Exogenous IL-4-Expressing Bone Marrow Mesenchymal Stem Cells for the Treatment of Autoimmune Sensorineural Hearing Loss in a Guinea Pig Model

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Chang-qiang Tan ◽  
Xia Gao ◽  
Lang Guo ◽  
He Huang
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Mesenchymal Stem Cells ◽  
Hearing Loss ◽  
Sensorineural Hearing Loss ◽  
Inner Ear ◽  
Sensorineural Hearing ◽  
Scala Tympani ◽  
Auditory Brain Stem Response ◽  
Marrow Mesenchymal Stem Cells

Bone marrow mesenchymal stem cells (BMSCs) expressing recombinant IL-4 have the potential to remediate inflammatory diseases. We thus investigated whether BMSCs expressing exogenous IL-4 could alleviate autoimmune sensorineural hearing loss. BMSCs isolated from guinea pigs were transfected with recombinant lentivirus expressing IL-4. A total of 33 animals were divided into three groups. Group A received scala tympani injection of IL-4-expressing BMSCs, and Group B received control vector-expressing BMSCs, and Group C received phosphate-buffered saline. The distribution of implanted BMSCs in the inner ears was assessed by immunohistochemistry and fluorescence microscopy. Auditory brain-stem response (ABR) was monitored to evaluate the auditory changes. Following BMSCs transplantation, the threshold levels of ABR wave III decreased in Groups A and B and significant differences were observed between these two groupsP<0.05. Transplanted BMSCs distributed in the scala tympani and scala vestibuli. In some ears with hearing loss, there was a decrease in the number of spiral ganglion cells and varying degrees of endolymphatic hydrops or floccule. Following transplantation, the lentivirus-infected BMSCs migrated to the inner ear and produced IL-4. Our results demonstrate that, upon transplantation, BMSCs and BMSCs expressing recombinant IL-4 have the ability to remediate the inflammatory injury in autoimmune inner ear diseases.

Pathology of labyrinthine ossification

1991 ◽  
Vol 105 (8) ◽  
pp. 621-624 ◽  
Author(s):  
Christopher deSouza ◽  
Michael M. Paparella ◽  
Pat Schachern ◽  
Tae H. Yoon
Keyword(s):  
Inner Ear ◽  
Otitis Media ◽  
Osseous Tissue ◽  
Scala Tympani ◽  
Fabry’S Disease ◽  
Fabry's Disease ◽  
Basal Turn ◽  
Vascular Compromise ◽  
Temporal Bones

AbstractOssification of the inner ear is the result of multifactorial pathogeneses, such as infection or malignant infiltration, and otosclerosis. Ossification of the innerear spaces is a well documented sequela of suppurative labyrinthitis. In this study of human temporal bones, sections from 14 patients (28 temporal bones)were studied. In additionto the osseous tissue within the inner ear, findings included neoplasms, otosclerosis, otitis media, trauma, and Fabry's disease. We have attempted to correlate these conditions and their influence on the formation of osseous tissue within the spaces of the inner ear. Tympanogenic infection and vascular compromise were found to play an important role in ossification. The scala tympani ofthe basal turn of the cochlea was frequently the site involved.

Reduction of Inner Ear Inflammation by Treatment with Anti-ICAM-1 Antibody

1997 ◽  
Vol 106 (12) ◽  
pp. 1070-1075 ◽  
Author(s):  
Tsuyoshi Takasu ◽  
Jeffrey P. Harris
Keyword(s):  
Monoclonal Antibody ◽  
Inner Ear ◽  
Therapeutic Approach ◽  
Inflammatory Cell ◽  
Inflammatory Cell Infiltration ◽  
Endolymphatic Sac ◽  
Experimental Paradigm ◽  
Scala Tympani ◽  
Immune Mediated

The in vivo effect of systemic administration of monoclonal antibody (mAb) against ICAM-1 (αICAM-1) in experimental immune-mediated labyrinthitis was evaluated. The αICAM-1–treated rats showed reduced inflammatory cell infiltration in the scala tympani and the perisaccular tissue of the endolymphatic sac. However, with this experimental paradigm, labyrinthitis could not be completely abolished. These findings suggest that ICAM-1–dependent pathways play an important role in the series of immunologic events occurring in the inner ear, and that the use of ICAM-1 antagonist may be a possible therapeutic approach to labyrinthitis.

scholarly journals A Surgical Navigation System for Guiding Exact Cochleostomy Using Auditory Feedback: A Clinical Feasibility Study

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Byunghyun Cho ◽  
Nozomu Matsumoto ◽  
Shizuo Komune ◽  
Makoto Hashizume
Keyword(s):  
Feasibility Study ◽  
Navigation System ◽  
Auditory Feedback ◽  
Surgical Navigation ◽  
Complex Structure ◽  
Electrode Array ◽  
Scala Tympani ◽  
Correct Placement ◽  
Surgical Navigation System ◽  
The Common

In cochlear implantation (CI), the insertion of the electrode array into the appropriate compartment of the cochlea, the scala tympani, is important for an optimal hearing outcome. The current surgical technique for CI depends primarily on the surgeon’s skills and experience level to achieve the correct placement of the electrode array, and the surgeon needs to confirm that the exact placement is achieved prior to completing the procedure. Thus, a surgical navigation system can help the surgeon to access the scala tympani without injuring important organs in the complex structure of the temporal bone. However, the use of a surgical microscope has restricted the effectiveness of the surgical navigation because it has been difficult to deliver the navigational information to the surgeon from outside of the surgeon’s visual attention. We herein present a clinical feasibility study of an auditory feedback function developed as a computer-surgeon interface that can guide the surgeon to the preset cochleostomy location. As a result, the surgeon could confirm that the drilling point was correct, while keeping his or her eyes focused on the microscope. The proposed interface reduced the common frustration that surgeons experience when using surgical navigation during otologic surgeries.

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