Histological Reaction in the Round Window Membrane after Cochlear Implant Insertion in Nonhuman Primates.

INTRODUCTION: The primary objective of this article was to determine if any histological alterations occur in the round window (RW) and adjacent anatomical structures of an animal model with normal hearing when a cochlear implant (CI) electrode array is inserted. Furthermore, this article aims to relate these histological alterations to the auditory changes generated. METHODS: Cochlear implantation was performed, following the principles of minimally traumatic surgery (MTS), in 15 ears of nonhuman primates (Macaca fascicularis) (Mf) with normal hearing. Auditory brainstem-evoked potentials (ABR) using clicks and tones were used prior to surgery and during a 6-month follow-up period. Histological evaluation was carried out, analyzing the position of the electrode array with respect to the round window membrane (RWM), its percentage of occupation and integrity, the presence of intracochlear damage, and the tissue reaction provoked, the latter of which was quantified in the temporal bones. RESULTS: Surgery was performed on all 15 ears without relevant incidences. Regarding histology, the electrode array in the RW of all ears presented a lateral position with respect to the modiolus. No lesions affecting the integrity of the RW were observed. The mean value of the array's occupation in the RW was 25%. Tissue reaction, in the form of fibrosis, was observed in all ears and more intensely in the trans-RWM and post-RWM areas. In all ears, the electrodes remained on the scala tympani. No profound hearing impairment was recorded in any ear, being the mean loss of 25.4 dB when comparing presurgical thresholds with those collected 6 months after implantation in ABR click and 24.4 dB in ABR tone burst. CONCLUSIONS: The animal model and Hybrid L-14 (HL14) electrode array were optimal for implementing a surgical technique similar to that routinely performed on humans. Mild histological alterations were observed in the round window membrane and adjacent anatomical structures from the insertion of a cochlear implant electrode array. Following the minimally invasive technique, levels of hearing preservation were satisfactory, reaching a pre-post difference of 25.4 dB in the ABR click and 24.4 dB for a high-frequency tone burst. Complete hearing impairment was not observed in either ear. Correlation between the severity of histological alterations and hearing changes recorded in the ABR studies was observed.

Cochlear Implantation With a Dexamethasone Eluting Electrode Array: Functional and Anatomical Changes in Non-Human Primates.

OBJECTIVES: The aim of this study was to determine whether the dexamethasone-eluting electrode (DEXEL) has a protective anti-inflammatory effect in a normal hearing implanted cochlea, as well as its performance and safety. DESIGN: Ten healthy and normal hearing cynomolgus macaques (Mf) were divided into two cohorts: DEXEL group (DG) (CONCERTO CI device containing a DEXEL) and conventional CI group (CG) (unmodified CONCERTO CI device). The electrode was inserted into the scala tympani via the round window with an angle of insertion of 270 degrees. Auditory, impedance, electrically evoked compound action potential (eCAP), and recovery of function measurements were recorded monthly until sacrifice at 6 months post-implantation. A histologic analysis was also performed. RESULTS: At 6 months, measurement of auditory brainstem responses revealed a mean threshold shift, as well as a mean impedance value, lower in the DEXEL group. The minimum eCAP for the remaining active contacts in the DEXEL group was 68% of that in the conventional CI group. Also at 6 months, the eCAP amplitude produced by a stimulating current of 800 cu (eCAP) was almost 2.5-fold higher in the DEXEL group than in the conventional CI group (1338.86 ±â€Š637.87 µV versus 545.00 ±â€Š137.37 µV; p = 0.049). Tissue reactions, in particular fibrosis and ossification, were more common in the conventional CI group. CONCLUSIONS: The CI electrode array equipped with a dexamethasone-eluting component tested in macaques evidence that delivery of dexamethasone to the inner ear may produce rapid and long-lasting improvement of hearing with fewer neural tissue reactions.

Cochlear Implant Electrode Array From Partial to Full Insertion in Non-Human Primate Model.

OBJECTIVES: To determine the feasibility of progressive insertion (two sequential surgeries: partial to full insertion) of an electrode array and to compare functional outcomes. MATERIAL AND METHODS: 8 normal-hearing animals (Macaca fascicularis (MF)) were included. A 14 contact electrode array, which is suitably sized for the MF cochlea was partially inserted (PI) in 16 ears. After 3 months of follow-up revision surgery the electrode was advanced to a full insertion (FI) in 8 ears. Radiological examination and auditory testing was performed monthly for 6 months. In order to compare the values a two way repeated measures ANOVA was used. A p-value below 0.05 was considered as statistically significant. IBM SPSS Statistics V20 was used. RESULTS: Surgical procedure was completed in all cases with no complications. Mean auditory threshold shift (ABR click tones) after 6 months follow-up is 19 dB and 27 dB for PI and FI group. For frequencies 4, 6, 8, 12, and 16 kHz in the FI group, tone burst auditory thresholds increased after the revision surgery showing no recovery thereafter. Mean threshold shift at 6 months of follow- up is 19.8 dB ranging from 2 to 36dB for PI group and 33.14dB ranging from 8 to 48dB for FI group. Statistical analysis yields no significant differences between groups. CONCLUSION: It is feasible to perform a partial insertion of an electrode array and progress on a second surgical time to a full insertion (up to 270º). Hearing preservation is feasible for both procedures. Note that a minimal threshold deterioration is depicted among full insertion group, especially among high frequencies, with no statistical differences.

[Idiopathic local bladder amyloidosis]. / Amiloidosis vesical primaria localizada idiopática.

OBJECTIVE: To report one case of primary bladder amyloidosis. METHODS: We studied a male patient with asymptomatic hematuria by means of transurethral resection. RESULTS: Pathologic features were consistent with amyloidosis of the bladder wall. We cannot prove either sites of amyloid deposits or an etiology for this disease. CONCLUSIONS: Local idiopathic bladder amyloidosis is a very rare disease and the most common presenting symptom is painless hematuria. It may be difficult to differentiate between this disease and a urothelial bladder neoplasia.

Amiloidosis vesical primaria localizada idiopática / Idiopathic local bladder amyloidosis

OBJETIVO: Describir un caso de amiloidosisvesical localizada idiopática.MÉTODOS: Se estudió un paciente varón con hematuriaasintomática mediante resección transuretral.RESULTADOS: El resultado histológico de las muestrasenviadas informó de amiloidosis vesical. El estudio posteriorno demostró depósitos de material amiloide en otralocalización ni etiología demostrable de la amiloidosis.CONCLUSIONES: La amiloidosis vesical localizada idiopáticaes una entidad poco frecuente cuya principal formade presentación es la hematuria y que puede ser difícil dediferenciar de una patología neoplásica de urotelio vesical

OBJECTIVE: To report one case of primary ;;bladder amyloidosis. ;;METHODS: We studied a male patient with asymptomatic ;;hematuria by means of transurethral resection. ;;RESULTS: Pathologic features were consistent with ;;amyloidosis of the bladder wall. We cannot prove either ;;sites of amyloid deposits or an etiology for this disease. ;;CONCLUSIONS: Local idiopathic bladder amyloidosis is ;;a very rare disease and the most common presenting ;;symptom is painless hematuria. It may be difficult to ;;differentiate between this disease and a urothelial bladder ;;neoplasia