Endocochlear inflammation in cochlear implant users: case report and literature review

Cochlear implantation is a relatively safe procedure with a low complication rate. The overall rate of complications among cochlear implant patients ranges from 6% to 20%. Major complications are those that are life-threatening or require surgery, whereas minor complications are those that can be medically treated. Nonetheless, certain complications, even if highly rare, may require specific investigations and treatments. Among these rare complications are those with endocochlear involvement, such as cochleitis or labyrinthitis, with fibrosis or ossification that could lead to explantation. The aims of the present study were to report a particular case of post-operative cochleitis and to review the rate of complications after cochlear implantation, emphasising those conditions with proven endocochlear involvement.

We refer to the case of an eight-year-old Italian boy affected by the sudden onset of headache, ipsilateral otalgia and facial paresis, who presented to our clinic for inexplicable worsening of the performance of his implant and his residual hearing, six years after surgery. A complete investigation including (clinical history, routine, autoimmune and serological blood tests, electrophysiological measurements from the cochlear implant and neuroimaging) was performed and is herein described. Additionally, a comprehensive review of the literature was conducted using internet search engines; 274 papers were selected, 88 of which were best suited to our purposes.

In our case, the progression of the symptoms and the performance decrement required explantation, followed by a complete recovery. Reviewing the literature revealed only three reports concerning cases of proven endocochlear phlogosis that required revision surgery. Wound swelling/infection and vertigo remain the two most common complications of cochlear implantation. Failure of the device is the third most frequent complication (10.06% of all complications and 1.53% of cochlear implantations). Other rare conditions (such as granulating labyrinthitis with cochlear fibrosis, ossification and erosion, silicone allergy and the formation of a biofilm around the internal device) are possible and unpredictable. Although rare (approximately 1%), such cases may require explantation.

Despite efforts by both surgeons and manufacturers, device-related and surgical complications still occur. These and other rare conditions demand specific management, and their frequency may be underestimated. Further studies are needed to assess more realistic rates of complications and devise more efficient strategies for early diagnosis and treatment.