Effects of CI on Tinnitus and Its Symptoms

Abnormal activity in the central auditory system is the cause of subjective experience of tinnitus. Electrical stimulation can inhibit the abnormal activity of auditory related neurons in patients with tinnitus. In recent years, the application of electrical stimulation in the treatment of tinnitus is a hot research topic, and has made some progress. However, its treatment is still in the discussion stage, and there is no best scheme suitable for clinical practice. At present, scholars have found that cochlear electrode stimulation can inhibit tinnitus, but its mechanism is not clear. It is difficult to locate the origin of tinnitus, and the location of electrode stimulation and stimulation parameters still need to be further optimized. Because the implanted part of the cochlear implant contains magnets, the patients cannot perform functional MRI. However, the prevalence of tinnitus in this group is very high (67.0\~100.0%, with an average of 80.0%), so it is of great value and significance to study the effect of tinnitus treatment in such patients. In this study, a new clinical electroencephalogram (EEG) technique was used to make up for the lack of MRI imaging in patients with electrode implantation. EEG analyzes the functional connection of different brain regions through EEG test electrodes, uses the traceability function of EEG software to locate the location of tinnitus, analyzes the process of tinnitus inhibition by electrical stimulation, and explains the mechanism of tinnitus inhibition by electrical stimulation from a new perspective.

1. Research content 1.1 Study on the change law of tinnitus affected by electrical stimulation after electrode implantation: 1) The change of tinnitus before operation after cochlear implantation; 2) Long term observation of electrical stimulation after cochlear implantation: (1) The change rule of tinnitus loudness after electrical stimulation (how long can it recover to be stable after power on); (2) The regularity of tinnitus frequency after electrical stimulation; (3) The recovery of tinnitus after electrode implantation for various causes of deafness.

   1.2 Study on the mechanism of electric stimulation inhibiting tinnitus: 1) Changes of resting EEG in patients with tinnitus before surgery, before surgery-after surgery, 1 month, 2 months, 3 months, 6 months, 12 month, more than 12 months; 2) The compilation of resting electroencephalogram analysis program; 3) The resting brain wave shape was analyzed to trace the anatomical position of the artificial cochlea to inhibit tinnitus.

   1.3 Study on the optimal setting of electrode stimulation for tinnitus treatment: 1) Setting different electric stimulation frequency and stimulation rate parameters to mask tinnitus; 2) Set the procedure of electric stimulation cochlear implant to mask tinnitus.
2. Research objectives 1) Summarize the changes of tinnitus after electrode implantation (effective treatment time, diseases suitable for electrical stimulation treatment, etc.); 2) Infer the mechanism of electric stimulation inhibiting tinnitus; 3) Set electrical stimulation parameters to effectively suppress tinnitus.
3. Scientific problems to be solved Our study group plan to use more advanced EEG technology to explore the principle of electric stimulation to suppress tinnitus, find out the effective scheme of electric stimulation to treat tinnitus, and help more patients solve the problem of tinnitus.

Eligibility Criteria:
Inclusion Criteria:

* 1. This study included patients who received cochlear implants at the Auditory Implant Center of the Otorhinolaryngology-Head and Neck Surgery, China PLA General Hospital;
* 2. The patients ranged from 16 to 90 years old;
* 3. The patient experienced hearing loss and had either tinnitus longer than 0.25 years (experimental group 1) or no tinnitus (control group 2) before the cochlear implant surgery;
* 4. The cochlear implants accepted by patients included products from MED-EL, Cochlear, Advanced Bionics and Nurotron;
* 5. All patients voluntarily participated in the study.

Exclusion Criteria:

* 1 Tinnitus types exclude non otogenic tinnitus (including tinnitus caused by hypertension, heart disease, hyperthyroidism, neurasthenia, hyperlipidemia, etc.);
* 2 Contraindications of cochlear implant surgery (refer to the guidelines for cochlear implant 2013 of the Chinese Medical Association);
* 3 Intellectual deficiency