Pain After Cochlear Implantation Without Signs of Inflammation: A Systematic Review.

Objectives: This review summarizes current evidence on causes and management strategies for delayed pain post-cochlear implantation (CI) surgery, without clinical evidence of inflammation or infection.

Methods: The systematic review was undertaken in line with Preferred Reporting Items for Systematic review and Meta-Analysis Protocols 2015 guidelines. A literature search was undertaken, with inclusion of patients who underwent CI and presented with delayed pain (>3 months post-operatively) around their device site without an identifiable cause. Analysis was undertaken using MATLAB (MathWorks, Natick, MA) and the R-software package (www.r-project.org).

Results: 4 articles (48 patients), all retrospective case series, met inclusion criteria. The mean onset of pain post-CI was 60 months and mean follow-up was 15.8 months, there was no difference in the prevalence of pain between device brands (p=0.13). The majority (90%) did not have any hearing deterioration, and investigations did not reveal a cause for the pain in any of the patients. In terms of management, medical therapies, including oral therapy (analgesia, non-steroidal anti-inflammatories, antibiotics) and local treatments (topical, injections) resolved pain in 41% and 63%, respectively. Surgical intervention (explantation, magnet replacement, tympanic neurectomy), where undertaken, resolved pain in 100%. A minority had an identifiable infective microorganism cultured from intra-operative soft tissue or biofilm samples.

Conclusions: Evidence for the causes and management of delayed pain post-CI without clinical evidence of inflammation is scarce. A stepwise approach is deemed best, with decisions being made on an individual basis, evaluating each patient's specific circumstances and priorities. Further evaluation of explanted devices would allow for better understanding of the causes and treatment of this group of patients.