Pain After Cochlear Implantation: An Unusual Complication?

OBJECTIVE: To analyze clinical signs and better define the underestimated long-term pain after implantation, to discuss etiological hypothesis, and to propose our department treatment algorithm and results. STUDY DESIGN AND
SETTING: Retrospective review of children implanted with complaints of atypical pain in the area of device implantation, not in the immediate postoperative period, more than or equal to 4 on the Visual Analog Pain Scale (VAPS: 0-10) in the ENT pediatric department of Trousseau and Necker Enfants Malades Hospitals between 1998 and 2015. PATIENTS: All patients had full clinical and electrophysiological checking, and had normal functioning device. Exclusion criteria were: related history of local trauma, ongoing skin infection, magnet displacement, and device failure. INTERVENTION(S): Treatments and outcomes were reviewed, with a minimum of 6 months follow up. Two groups were analyzed: Group PS: pain associated with local swelling (n = 9) and Group P: isolated pain (n = 11). The first-line treatment was medical. In Group PS, anti-inflammatory, pain medication, and antibiotics were used at the same time; in Group P, only anti-inflammatory and pain medication was used. MAIN OUTCOME MEASURE(S): Success was defined when complete resolution of pain and swelling (pain scale = 0).
RESULTS: Twenty cases out of the 1,448 implanted patients in our department (1.4%) were included. Average age at first occurrence of pain was 15 years (3-22 yr). Mean delay between surgery and pain complaint was 5.8 years (0.25-14). Mean follow up was 2 years (0.5-5 yr).First line medical treatment was successful in eight cases (40%). Of the 12 patients who failed medical treatment and required surgery, two had resolution of pain with magnet change and 10 had resolution with reimplantation. (5/9 patients in Group PS and 7/11 in Group P).Microbiology was performed in 10/20 cases and analysis of explanted devices was performed in 7/10 cases. Positive microbiological culture of soft tissues was positive for 3/10 cases, biofilm was positive for 5/7 cases.Pain in the area of the implanted device can occur shortly after surgery or on long-term follow up. It has been seen in all device types. Pain may be clinically underestimated, as low VAPS grade (<5) or intermittent pain may be not reported. Low-grade infections might be a hypothesis to explain these pain. Management may include medical or surgical intervention.
CONCLUSION: Pain in the implanted area can be a major complication leading to implant non-use. Rate may be underestimated because of the lack of medical report. At explantation, we recommend systematic evaluation of biofilm and device failure regardless of the suspected etiology of the pain.