Intracochlear tPA infusion may reduce fibrosis caused by cochlear implantation surgery

Abstract

Background: Experiments show that the extent of ongoing fibrotic change within the cochlea can be determined by the volume and pattern of bleeding within the first 24 h following cochlear implantation. Tissue-type plasminogen activator (tPA) is effective at reducing thrombus volume when administered both within and external to the systemic circulation.

Aims/Objectives: To determine if tPA delivered into the scala tympani immediately following implantation will reduce thrombus volume within the lower basal turn of the cochlea.

Materials and Methods: Guinea pigs were implanted with either ‘soft’ or ‘hard’ arrays and administered tPA or saline via an intra-cochlear infusion immediately after implantation. Hearing was checked prior to, and 2 weeks after implantation. Cochleae were then harvested and imaged.

Results: Animals implanted with ‘soft’ arrays had 4.2% less tissue response compared with animals implanted with ‘hard’ arrays. In animals receiving ‘soft’ arrays, tPA reduced the volume of tissue response (measured by the percentage of the lower basal turn of the scala tympani occupied by tissue response) compared with saline.

Conclusions and Significance: tPA may be effective in reducing the overall volume of tissue response in routine ‘soft’ cochlear implantation and may have a greater effect in the event of significant surgical trauma.

Chinese abstract

背景：实验表明, 耳蜗内持续的纤维化程度可以通过人工耳蜗植入后最初24小时内的出血量和出血型式来确定。当在体循环之内和之外施用时, 组织型纤溶酶原激活物（tPA）在降低血栓量方面是有效的。

目的：确定植入后立即向鼓膜输入tPA是否会减少耳蜗下基底转弯内的血栓量。

材料和方法：对豚鼠植入“软”或“硬”阵列, 并在植入后立即通过耳蜗内输入注射tPA或盐水。在植入前和植入后2周检查听力, 然后将耳蜗取出并对其进行成像。

结果：与植入“硬”阵列的动物相比, 植入“软”阵列的动物的组织反应低4.2％。在接受“软”阵列的动物中, 与生理盐水相比, tPA减少了组织反应量（通过组织反应占据的鼓室鼓膜下基转的百分比来测量）。

结论和意义：tPA可有效降低常规“软”人工耳蜗植入时组织反应总量, 并可在发生严重手术创伤时起更大的作用。

Keywords:

• Cochlear implant
• tPA
• tissue response
• surgical trauma
• auditory brainstem response
• TSLIM

Disclosure statement

No potential conflict of interest was reported by the authors.

Acknowledgment

The authors acknowledge Mr Cameron Patrick from the Statistical Consulting Centre and Melbourne Statistical Consulting Platform (The University of Melbourne) for his assistance with statistical analysis and presentation, and Helen Feng and Dimitra Stathopoulos for their assistance with manufacture of the electrode arrays.

Additional information

Funding

This research was funded in part by a generous bequest from the late Gordon Darling, AC. JKC is a recipient of the Hugh Noel Puckle Scholarship.