Abstract
Objective
To quantify the potential effectiveness of cochlear implantation for tinnitus suppression in patients with single-sided deafness using the Tinnitus Handicap Inventory.
Methods
The study included 12 patients with unilateral tinnitus who were undergoing cochlear implantation for single-sided deafness. The Tinnitus Handicap Inventory was administered at the patient’s cochlear implant candidacy evaluation appointment prior to implantation and every cochlear implant follow-up appointment, except activation, following implantation. Patient demographics and speech recognition scores were also retrospectively recorded using the electronic medical record.
Results
A significant reduction was found when comparing Tinnitus Handicap Inventory score preoperatively (61.2 ± 27.5) to the Tinnitus Handicap Inventory score after three months of cochlear implant use (24.6 ± 28.2, p = 0.004) and the Tinnitus Handicap Inventory score beyond 6 months of CI use (13.3 ± 18.9, p = 0.008). Further, 45% of patients reported total tinnitus suppression. Mean CNC word recognition score improved from 2.9% (SD 9.4) pre-operatively to 40.8% (SD 31.7) by 6 months post-activation, which was significantly improved from pre-operative scores (p = 0.008).
Conclusion
The present data is in agreement with previously published studies that have shown an improvement in tinnitus following cochlear implantation for the large majority of patients with single-sided deafness.
1
Introduction
Single-sided deafness (SSD) is a type of hearing loss in which an individual has non-functional hearing in one ear and no greater than a mild hearing loss in the opposite ear. SSD is reported to affect approximately 18.1 million people in the United States . Common causes of SSD include sudden idiopathic sensorineural hearing loss, temporal bone trauma, Meniere’s disease, and infection (labyrinthitis, mumps, meningitis). Single sided deafness is often associated with significant audiologic consequences, particularly in cases of sudden hearing loss. In these situations, patients may experience difficulty adapting to the loss of hearing in one ear especially when attempting to localize sounds or converse in a noisy environment such as a restaurant . Patients with SSD frequently also experience tinnitus, which can have a profound impact on an individual’s quality of life. Specifically, tinnitus has been associated with an increased incidence of depression, anxiety, difficulty concentrating, insomnia, and headaches in the general population .
While the underlying etiology of tinnitus is still debated, one hypothesis is that the perception arises from changes in neural activity caused by reduced or lack of auditory input due to hearing loss . For patients with functional hearing in the affected ear, auditory deprivation can be overcome through the use of hearing aids. However, for people with severe to profound sensorineural hearing loss, hearing aids and other forms of sound enrichment are not useful for tinnitus treatment. In recent years, patients with severe to profound hearing loss have sought cochlear implantation as a means of tinnitus relief when other treatments were found to be ineffective. Emerging evidence supports the effectiveness of cochlear implantation as a treatment for tinnitus in the majority of individuals implanted for SSD; however, a small subset of patients continues to suffer with debilitating tinnitus . The aggregate number of patients in these studies remains small; therefore the benefits of cochlear implantation in these circumstances deserve further investigation.
Given the above, the objectives of the present study are as follows: 1) report tinnitus and speech perception outcomes of patients with SSD and tinnitus implanted at Vanderbilt University Medical Center, and 2) investigate potential explanations for why a small percentage of subjects do not receive relief from their tinnitus following cochlear implantation.
2
Materials & methods
2.1
Subjects
Retrospective review of prospectively collected data from patients undergoing cochlear implantation for SSD at Vanderbilt University Medical Center was performed. The study was approved by the International Review Board. Eligible participants were adults (18 years and older) with unilateral severe to profound sensorineural hearing loss and normal hearing in the contralateral ear. Twelve (12) subjects were enrolled. Normal hearing was defined as a pure tone average (PTA) of 25 dB HL or better. Eligibility criteria also included unilateral tinnitus perception of any degree. Patients undergoing implantation for SSD who denied tinnitus were excluded from this study.
2.2
Methods
Tinnitus was assessed using the Tinnitus Handicap Inventory (THI) prospectively. The THI is a 25-item questionnaire designed to assess the patient’s perceived handicap as a result of their tinnitus. A point value is assigned to each possible answer, the points are added together, and a severity of tinnitus handicap is determined. The patient’s total score can range from 0 to 100, with a higher score indicating a greater handicap. The THI also provides five grades of severity: Grade 1 (0–16, slight or no handicap), Grade 2 (18–36, mild handicap), Grade 3 (38–56, moderate handicap), Grade 4 (58–76, severe handicap), and Grade 5 (78–100, catastrophic handicap). The THI was administered at the patient’s cochlear implant (CI) candidacy evaluation appointment prior to implantation, and then, it was administered at every CI follow-up appointment, except activation, following implantation. Follow-up appointments were scheduled in accordance with our clinic’s normal protocol—one month, three months, six months, and twelve months post-implantation.
Patient demographics and audiologic data were retrospectively recorded using the electronic medical record. Audiologic and speech recognition data was conducted in accordance with Vanderbilt’s standard CI protocol. Audiometric thresholds were completed in a double-walled sound treated booth. Thresholds were obtained for 125, 250, 500, 750, 1000, 1500, 2000, 3000, 4000, 6000, and 8000 Hz via air conduction presented under insert earphones. Masking was implemented where appropriate.
Speech recognition was assessed as recommended by the revised Minimum Speech Test Battery for adult CI recipients. All speech recognition testing was completed in a double-walked sound treated booth. Stimuli was presented at 60 dBA through a single loudspeaker positioned at zero degrees azimuth approximately 1 m from the listener. The patient’s contralateral, normal hearing ear was plugged with an E.A.R. foam earplug and covered with a supraaural headphone.
The primary audiologic outcome of interest was the Consonant Nucleus Consonant (CNC) word recognition score. Testing consisted of monosyllabic words preceded by a carrier word, which are arranged into lists of 50 words (ex. “Ready, bird”) . Participants were instructed to repeat as much of each word as possible and encouraged to guess when necessary. Each phoneme and each word are scored individually, which results in an overall phoneme percentage correct score and an overall word percentage correct score.
2.3
Statistical analysis
Analyses were performed with GraphPad Prism 7.0 . For continuous variables, values were determined to follow a normal distribution using a D’Agostino and Perason omnibus normality test. Paired t- test or Wilcoxon signed rank test was used to assess changes in speech recognition over time. A value of p < 0.05 was considered indicative of statistical significance.
2
Materials & methods
2.1
Subjects
Retrospective review of prospectively collected data from patients undergoing cochlear implantation for SSD at Vanderbilt University Medical Center was performed. The study was approved by the International Review Board. Eligible participants were adults (18 years and older) with unilateral severe to profound sensorineural hearing loss and normal hearing in the contralateral ear. Twelve (12) subjects were enrolled. Normal hearing was defined as a pure tone average (PTA) of 25 dB HL or better. Eligibility criteria also included unilateral tinnitus perception of any degree. Patients undergoing implantation for SSD who denied tinnitus were excluded from this study.
2.2
Methods
Tinnitus was assessed using the Tinnitus Handicap Inventory (THI) prospectively. The THI is a 25-item questionnaire designed to assess the patient’s perceived handicap as a result of their tinnitus. A point value is assigned to each possible answer, the points are added together, and a severity of tinnitus handicap is determined. The patient’s total score can range from 0 to 100, with a higher score indicating a greater handicap. The THI also provides five grades of severity: Grade 1 (0–16, slight or no handicap), Grade 2 (18–36, mild handicap), Grade 3 (38–56, moderate handicap), Grade 4 (58–76, severe handicap), and Grade 5 (78–100, catastrophic handicap). The THI was administered at the patient’s cochlear implant (CI) candidacy evaluation appointment prior to implantation, and then, it was administered at every CI follow-up appointment, except activation, following implantation. Follow-up appointments were scheduled in accordance with our clinic’s normal protocol—one month, three months, six months, and twelve months post-implantation.
Patient demographics and audiologic data were retrospectively recorded using the electronic medical record. Audiologic and speech recognition data was conducted in accordance with Vanderbilt’s standard CI protocol. Audiometric thresholds were completed in a double-walled sound treated booth. Thresholds were obtained for 125, 250, 500, 750, 1000, 1500, 2000, 3000, 4000, 6000, and 8000 Hz via air conduction presented under insert earphones. Masking was implemented where appropriate.
Speech recognition was assessed as recommended by the revised Minimum Speech Test Battery for adult CI recipients. All speech recognition testing was completed in a double-walked sound treated booth. Stimuli was presented at 60 dBA through a single loudspeaker positioned at zero degrees azimuth approximately 1 m from the listener. The patient’s contralateral, normal hearing ear was plugged with an E.A.R. foam earplug and covered with a supraaural headphone.
The primary audiologic outcome of interest was the Consonant Nucleus Consonant (CNC) word recognition score. Testing consisted of monosyllabic words preceded by a carrier word, which are arranged into lists of 50 words (ex. “Ready, bird”) . Participants were instructed to repeat as much of each word as possible and encouraged to guess when necessary. Each phoneme and each word are scored individually, which results in an overall phoneme percentage correct score and an overall word percentage correct score.
2.3
Statistical analysis
Analyses were performed with GraphPad Prism 7.0 . For continuous variables, values were determined to follow a normal distribution using a D’Agostino and Perason omnibus normality test. Paired t- test or Wilcoxon signed rank test was used to assess changes in speech recognition over time. A value of p < 0.05 was considered indicative of statistical significance.
3
Results
3.1
Patient characteristics
Twelve participants met inclusion criteria. The majority of patients were male (83.3%), with a mean age at the time of cochlear implantation of 51.6 ± 15.5 years. The etiology of SSD, duration of deafness, electrode implanted, and PTA in the non-implanted ear are detailed in Table 1 . Mean pre-operative PTA was 13.2 ± 5.9 dB in the non-implanted ear, and 87.7 ± 19.3 dB in the ear to be implanted. Average unaided pre-operative pure-tone thresholds at individual frequencies are plotted for both ears in Fig. 1 .
