Delivering Speech by Non-Invasive Electric Stimulation of the Central Nervous System / 대한이비인후과학회지

Recent advances in neuroscience and precise electric stimulation have enabled us to deliver complex signals to the central nervous system. But most of the successful electric stimulation devices such as cochlear implant and deep brain stimulation require surgery. Considering that most of the patients with hearing loss have a significant residual hearing, it is not feasible to open up the round window and insert an electrode in a functional cochlea. The concept of non-invasive electric stimulation of the auditory system may have a role in the future to overcome this unmet need in the clinic. Until now, many researchers have tried to delivery speech signal to the brain by means of non-invasive electric stimulation. Trans-cranial electric stimulation have most extensively been studied and interesting outcomes have recently been published. Some studied were able to prove that the envelope of the speech can be delivered by non-invasive electric stimulation. This new technology is called speech entrainment. By inducing speech entrainment, researchers were able to enhance the speech recognition score in noisy environments. But there are also some limitations in this approach. For instance, the time delay of the auditory sound and brain entrainment must be matched which is quite challenging. Although some limitation needs to be resolved, recent advancements in this new field is very interesting. More developments will follow in the next few years that can help patients with hearing loss in the near future.

Effect of Speech Degradation and Listening Effort in Reverberating and Noisy Environments Given N400 Responses

Background and Objectives@#In distracting listening conditions, individuals need to pay extra attention to selectively listen to the target sounds. To investigate the amount of listening effort required in reverberating and noisy backgrounds, a semantic mismatch was examined. @*Subjects and Methods@#Electroencephalography was performed in 18 voluntary healthy participants using a 64-channel system to obtain N400 latencies. They were asked to listen to sounds and see letters in 2 reverberated×2 noisy paradigms (i.e., Q-0 ms, Q-2000 ms, 3 dB-0 ms, and 3 dB-2000 ms). With auditory-visual pairings, the participants were required to answer whether the auditory primes and letter targets did or did not match. @*Results@#Q-0 ms revealed the shortest N400 latency, whereas the latency was significantly increased at 3 dB-2000 ms. Further, Q-2000 ms showed approximately a 47 ms delayed latency compared to 3 dB-0 ms. Interestingly, the presence of reverberation significantly increased N400 latencies. Under the distracting conditions, both noise and reverberation involved stronger frontal activation. @*Conclusions@#The current distracting listening conditions could interrupt the semantic mismatch processing in the brain. The presence of reverberation, specifically a 2000 ms delay, necessitates additional mental effort, as evidenced in the delayed N400 latency and the involvement of the frontal sources in this study.

Effects of Residual Hearing on the Auditory Steady State Response for Cochlear Implantation in Children

BACKGROUND AND OBJECTIVES: We aim to explore the effects of residual auditory steady state response (ASSR) on cochlear implantation (CI) outcomes in children lacking auditory brainstem responses (ABRs). SUBJECTS AND METHODS: We retrospectively reviewed the data of child CI recipients lacking ABRs. All ears were divided into two groups: with residual ASSR and without ASSR. For each frequency, the T- and C-levels and the electrical dynamic ranges of postoperative 3-month and 1-year mappings were compared between the groups. To evaluate speech perception, patients who received simultaneous bilateral CIs were divided into two groups: group 1 exhibited responses at all frequencies in both ears; in group 2, at least one ear evidenced no response. The Categories of Auditory Perception (CAP) and Infant-Toddler Meaningful Auditory Integration Scale (IT-MAIS) scores were compared between the groups. RESULTS: We enrolled 16 patients. At 2 kHz, the postoperative 3-month and 1-year T-levels of patients with residual hearing were lower than those of hearing loss group (p=0.001, p=0.035). In residual hearing group, the ASSR threshold correlated positively with the postoperative 1-year T-level (p=0.012, R² =0.276) and C-level (p=0.002, R² =0.374). Of 10 simultaneous bilateral CI recipients, 5 exhibited ASSRs at all frequencies and the other 5 showed no response at ≥1 frequency. The latter had higher CAP scores at the postoperative 1-year (p=0.018). CONCLUSIONS: In children exhibiting hearing loss in ABR testing, residual hearing at 2 kHz ASSR correlated positively with the post-CI T-level. Those with ASSRs at all frequencies had significantly lower CAP scores at the postoperative 1year. CI should not be delayed when marginal residual hearing is evident in ASSR.

Noise and Room Acoustic Conditions in a Tertiary Referral Hospital, Seoul National University Hospital

BACKGROUND AND OBJECTIVES: Noise levels and room acoustic parameters at a tertiary referral hospital, Seoul National University Hospital (SNUH) in Korea, are investigated. MATERIALS AND METHODS: Through a questionnaire, acoustically problematic rooms are identified. Noise levels in emergency rooms (ERs) and intensive care units (ICUs) are measured over about three days. Acoustically critical and problematic rooms in the otolaryngology department are measured including examination rooms, operating rooms, nurse stations, receptions, and patient rooms. RESULTS: The A-weighted equivalent noise level, L(Aeq), ranges from 54 to 56 dBA, which is at least 10 dB lower than the noise levels of 65 to 73 dBA measured in American ERs. In an ICU, the noise level for the first night was 66 dBA, which came down to 56 dBA for the next day. The noise levels during three different ear surgeries vary from 57 to 62 dBA, depending on the use of surgical drills and suctions. The noise levels in a patient room is found to be 47 dBA, while the nurse stations and the receptions have high noise levels up to 64 dBA. The reverberation times in an operation room, examination room, and single patient room are found to be below 0.6 s. CONCLUSIONS: At SNUH, the nurse stations and receptions were found to be quite noisy. The ERs were quieter than in the previous studies. The measured reverberation times seemed low enough but some other nurse stations and examination rooms were not satisfactory according to the questionnaire.

Proposal on the Diagnostic Criteria of Definite Isolated Otolith Dysfunction

BACKGROUND AND OBJECTIVES: Dizzy patients with abnormal otolith function tests, despite a normal caloric response, are defined as having specific (isolated) otolith organ dysfunction. This study was performed to compare the differences in clinical presentation between isolated otolith dysfunction (iOD) patients with lab- and Sx-based iOD group and lab-based iOD symptoms. SUBJECTS AND METHODS: The medical records of 23 iOD patients with normal caloric response but abnormal cervical vestibular evoked myogenic potential (VEMP), ocular VEMP, or subjective visual vertical were reviewed. Non-spinning vertigo was considered as otolith-related symptoms. The patients’ age, onset of dizziness, Numeric Rating Scale on the severity of dizziness, and concomitant vestibular disorders were analyzed. RESULTS: Patients in the lab-based iOD group were significantly older than those in the lab- and Sx-based iOD group. Known vestibular disorders were significantly more common in the lab-based iOD group (83.3%) compared to the lab- and Sx-based iOD group (18.2%). Despite the normal caloric response, catch-up saccade was found in the video head impulse test in more than half (54.5%) of the lab-based iOD group patients. There was no catch-up saccade in the lab- and Sx-based iOD group. There were no significant differences in gender ratio, frequency of dizziness attacks, and duration of illness. CONCLUSIONS: We propose new definitions of definite iOD (lab- and Sx-based iOD) and probable iOD (lab- or Sx-based iOD). These new definitions may help researchers to identify patients who are more likely to have true iOD, and facilitate comparisons of results between different studies.

Recovery Phase Spontaneous Nystagmus, Its Existence and Clinical Implication

BACKGROUND AND OBJECTIVES: Determination of the lesion side based on the direction of the nystagmus could result in confusions to the clinicians due to mismatch between the vestibular function tests and also between vestibular and audiologic features. To minimize these mistakes, we elucidated the clinical manifestation and vestibular function test results in cases with recovery spontaneous nystagmus (rSN). SUBJECTS AND METHODS: Patients who visited ENT clinic of tertiary referral hospital for acute onset continuous vertigo from January 2008 to December 2011 were enrolled. In these patients, we assessed onset time of vertigo, time point of paralytic spontaneous nystagmus (SN) and time point of rSN. At each time point of SN, vestibular function tests and hearing function tests were performed. RESULTS: We confirmed the rSN among patients with unilateral vestibulopathy and demonstrated that high gain of the rotatory chair test (slow harmonic acceleration) and/or mismatch of the SN direction and contralateral caloric weakness could indicate the recovery state of patients and nystagmus observed in this stage is recovery phase nystagmus. CONCLUSIONS: In acute vestibulopathy patients, recovery phase nystagmus was observed and on this stage of disease vestibular function tests shows several features that could predict recovery state.

Clinical Application and Updates on Vestibular Evoked Myogenic Potential: Proposal for Future Development in Vestibulopathy / 대한평형의학회지

Both cervical vestibular evoked myogenic potential (cVEMP) and ocular VEMP (oVEMP) are irreplaceable tools in the current vestibular science, but they have many drawbacks. For example, the test-retest reliability of the asymmetry ratio is inadequate for both tests. The American Academy of Neurology noted that there is insufficient evidence to determine whether cVEMP and oVEMP can accurately identify vestibular function specifically related to the saccule/utricle. One of the most important factors underlying the variability of cVEMP seems to be the control of, and compensation for, baseline muscle contraction power. Reasons for variability in oVEMP include a poor signal to noise ratio, the angle of superior gaze, effective and controlled presentation of stimuli, intracranial pressure, and electrode location. Many of these shortcomings could be improved by further development of recording methods and devices. This article examines the reasons for the insufficient reliability of VEMP and proposes avenues for improvement of VEMP recording systems.

Clinical Implication and Proposed Mechanism of Direction Changing Vibration Induced Nystagmus in Unilateral Vestibular Hypofunction / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: We evaluated the clinical characteristics and vestibular function of patients with direction changing vibration induced nystagmus (DC VIN) and unilateral vestibular hypofunction and suggest clinical implication and a proposed mechanism of DC VIN. SUBJECTS AND METHOD: The records of 315 patients who underwent the VIN test were reviewed retrospectively. Among these, 18 patients (5.7%) showed DC VIN, and out of whom, 15 patients (4.8%) were diagnosed as unilateral vestibular hypofunction by caloric, rotation chair (RCT), and video head impulse test (vHIT). We analyzed the relationship between DC VIN and the dizziness characteristics, duration of disease, and the outcome of the vestibular function test. RESULTS: The mean age of 15 patients was 67.4±10.7 years and the mean duration of dizziness was 13.6±29.7 months. The caloric test revealed 25% of the patients to have significant canal paresis [Caloric vestibular neuritis (VN)], while 75% showed normal caloric response. However, unilateral vestibular hypofunction was observed by abnormal results in RCT or vHIT (Non-caloric VN). Seven patients showed ipsilateral DC VIN (nystagmus to vibrated side) and eight patients contralateral DC VIN (nystagmus to opposite side of vibration). Patients with ipsilateral DC VIN were shown to have a significant longer duration of dizziness than those with contralateral DC VIN. CONCLUSION: Although rare, DC VIN can also be found in patients with unilateral vestibular hypofunction. Patients with DC VIN had a mild vestibular asymmetry with Non-caloric VN or Caloric VN in the process of compensation. The mechanism of ipsilateral DC VIN seems to be due to the small amount of vestibular asymmetry, which is smaller than the interaural attenuation of vibration.

Comparisons in Outcome and Subject Comfort between Rotation Chair Systems

BACKGROUND AND OBJECTIVES: A rotation chair test has been used to evaluate the function of the horizontal semicircular canals. Currently, two chair systems according to the presence of cylindrical darkroom are used in a clinic setting. However, it has not been thoroughly investigated whether one system is superior to the other system or not. In this study, we aimed to compare test outcomes and subject convenience between two systems. SUBJECTS AND METHODS: Twenty subjects with no history of otologic disease were enrolled. Subjects were tested with two systems: system [A] with a cylindrical chamber and system [B] with no chamber. The results of sinusoidal harmonic acceleration (SHA), step velocity (SV), and visual fixation (VFX) tests were compared between the systems. Subject convenience was assessed with a questionnaire survey and results were compared between the systems. RESULTS: There were no significant differences in gain or asymmetry in SHA test between the systems. However, the phase of system [A] was significantly lower than that of system [B] at 0.16 Hz. There was no significant difference between the systems in directional preponderance (DP) gain or DP time constant. Regarding the VFX test, gain was higher in system [A] than system [B]. Subjects reported less stuffiness and less anxiety with system [B] than system [A], while preferring the system [A] goggles. CONCLUSIONS: A rotation chair system without a darkroom can provide a more comfortable experience for subjects in terms of stuffiness and anxiety, while showing comparable results in SHA and SV tests with a darkroom system.

Central Apogeotropic Direction Changing Positional Nystagmus due to Fourth Ventricle Mass Mimicking Horizontal Canal Cupulolithiasis Benign Paroxysmal Positional Vertigo / 대한평형의학회지

In some dizzy patients the apogeotropic direction changing positional nystagmus (DCPN) can be caused by a central disorder such as a mass lesion near the fourth ventricle or infaction. We have recently encountered a patient who showed a central DCPN mimicing a horizontal canal cupulolithiasis benign paroxysmal positional vertigo (BPPV). A 4.1 cm sized tumor was filling the fourth ventricle before the operation. When the head was turned to the left side vigorous right beting nystagmus was found. When the head was turned to the right side vigorous left beting nystagmus was found. But unlinke the typical horizontal canal BPPV, bowing and lying down position did not elicit any nystagmus. In order to see if the central DCPN was a transient finding or a persistent finding, we checked the nystagmus 3 weeks after the first testing. The same pattern of nystagmus was found again. The video head impulse test gain of all six canals were within the normal limit. In this article we discuss the points how to suspect a central DCPN in such cases.

The Principle and Methodology of Vestibular Evoked Myogenic Potential / 대한평형의학회지

Vestibular evoked myogenic potential (VEMP) has developed as a broadly applied vestibular function test in clinics from its introduction in 1992. In the past, there was only one well known VEMP protocol, which is cervical VEMP, however recently ocular VEMP is also popular. Therefore, clarifying the VEMP recording protocol (cervical VEMP or ocular VEMP) before discussing the VEMP result has become essential. There is considerable difference regarding this VEMP test from other vestibular function tests. VEMP is thought to be assessing the functions of the otolith organs (utricle and saccule) which are evoked by acoustic stimulus. Cervical VEMP is valuable since this is the only available test method which could speculate the function of the saccule and inferior vestibular nerve. Still, there's less clearly understood part regarding the central pathway of VEMP. However, many clinicians and researchers participating in vestibular research speculate that this functional test will have a more dominant role in the near future. Here we describe the basic principles and methodological considerations regarding VEMP recording.

Correlation between Tinnitus Induced Distress and Sleep Quality / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: There exist few studies about relationship between tinnitus and sleep disturbance. Furthermore, the currently available studies have some limitations of confounding factors. This study evaluated correlation between tinnitus and sleep quality, especially by controlling depression and anxiety factors. SUBJECTS AND METHOD: The present study was planned as a cross sectional study using questionnaires. Using 46 patients with tinnitus, sleep quality was investigated by Pittsburgh Sleep Quality Index (PSQI) score, anxiety by State-Trait Anxiety Inventory (STAI, axis1 and axis2), depression by Beck Depression Inventory (BDI), and tinnitus induced distress by Tinnitus Handicap Inventory (THI). The final analysis method was multiple regression analysis. THI and PSQI were regarded as dependent and independent variables, respectively. BDI and STAI were regarded as confounding factors. RESULTS: Each factor (PSQI, two STAI, and BDI) revealed significant correlation with THI score. Considering four factors together with regression analysis, PSQI score was the most influencing factor on THI score (p=0.002). CONCLUSION: Although depression and anxiety were both influencing factors on tinnitus-induced distress as known previously, sleep quality influenced tinnitus-induced distress came out as the most significant factor in the multivariable analysis.

Erratum: Determinants of Conductive Hearing Loss in Tympanic Membrane Perforation: Correction of the Sixth Author Name

The sixth author's name should have been given as Myung-Whan Suh.

In Reply: Broad Band Noise May be Preferable, Even After Controlling the Pretreatment Severity of Tinnitus Induced Distress

No abstract available.

Effect of Different Sounds on the Treatment Outcome of Tinnitus Retraining Therapy

OBJECTIVES: The purpose of this study was to evaluate the therapeutic effect of three different types of sounds on tinnitus patients undergoing tinnitus retraining therapy (TRT). METHODS: This is a single-institution retrospective study, performed in one tertiary otological referral center. Thirty-eight adults with subjective idiopathic tinnitus who were followed for at least 9 weeks were enrolled. Sound therapy was delivered in 3 different ways: narrowband noise TRT (nTRT); mixed band noise TRT (mTRT); broadband noise TRT (bTRT). Treatment response was measured through validated psychometric questionnaires: Tinnitus Handicap Inventory (THI), visual analog scale (VAS) on annoyance, and numerical description of hours of tinnitus perception (awareness hours). RESULTS: A total of 38 patients were followed for at least 9 weeks. In nTRT group, all outcome measures including THI, VAS, and the awareness hours, decreased over 9 weeks with no statistical significance. In mTRT group, all outcome measures except for awareness hours significantly improved 9 weeks after the beginning of the treatment. In bTRT group, all outcome measures decreased significantly in 9 weeks. When therapeutic success is defined as improvement in THI 7 or more, bTRT group (77.8%) showed a higher success rate than other groups for 38 patients with the minimum follow-up of 9 weeks. CONCLUSION: All three sounds can provide relief in patients with annoying tinnitus after TRT. However, there is difference in the therapeutic effect according to sound types. Broadband sound seems to be better than narrowband sound or mixed sound in relieving the patients from tinnitus. Therefore, sound therapy with broadband noise may be more appropriate during TRT, but further evidence is needed for precise conclusion.

Preoperative Vestibular Function in Adults with Cochlear Implantation: Comparison between Prelingual and Poslingual Deafness / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Cochlear system and vestibular system have close relationship anatomically and developmentally. According to previous literatures, there are high incidences of vestibular dysfunction in subjects with severe hearing loss. The aim of this study is to validate the status of vestibular function in adults with profound hearing loss, and to compare the status of vestibular function between pre-lingual and post-lingual deaf. SUBJECTS AND METHOD: Vestibular function of 59 patients who had profound hearing loss was reviewed retrospectively. Patient's information and audiometry, Korean version Central Institute for the Deaf (KCID) scores, caloric test, rotation chair test and vestibular evoked myogenic potential (VEMP) were analyzed. The subjects were divided into two groups, prelingual deaf (pre-LD, n=12) and postlingual deaf (post-LD, n=47). We analyzed the difference between two groups. RESULTS: Fifty nine point six percent of patients showed hypo-function in caloric test. In the rotational chair test, abnormality of step velocity gain (43.1%), time constant (51.8%), sinusoidal harmonic acceleration (SHA)-gain (53.4%), SHA-phase lead (29.1%) and SHA-asymmetry (23.6%) were found. There was unilateral (20.0%) and bilateral (37.5%) hypo-function when VEMP was tested. Between pre-LD and post-LD groups, VEMP test revealed statistically significant difference between two groups (p=0.020). Post-LD groups had more patients of unilateral or bilateral hypofunction in VEMP test. The KCID score showed no significant correlation with vestibular functions. CONCLUSION: The patients of bilateral profound hearing loss showed unilateral or bilateral vestibular functional abnormality despite of no dizziness. Prevalence of lateral canal dysfunction does not seem to be different between pre-LD group and post-LD group. And post-LD groups have higher probability of saccular dysfunction than pre-LD.

Multicenter Study on the Clinician's Diagnostic and Therapeutic Approaches for Benign Paroxysmal Positional Vertigo in Korea / 대한평형의학회지

BACKGROUND AND OBJECTIVES: It is necessary to establish the most efficient diagnostic and therapeutic method for benign paroxysmal positional vertigo (BPPV), which is appropriate for Korean healthcare system. We aimed to evaluate current state of Korean clinician's diagnostic and therapeutic approaches for BPPV. MATERIALS AND METHODS: A 16-item survey was emailed to the members of dizziness department of Otology Research Interest Group in the Korean Otologic Society (n=68). 43 were returned and analyzed. RESULTS: All respondents (100%) used Dix-Hallpike test as a diagnostic tool for vertical canal-BPPV. Supine roll test was used for diagnosing lateral canal BPPV in nearly all the respondents (97.7%). Epley maneuver was chosen as otolith repositioning maneuver (ORM) for posterior canal BPPV in all respondents and barbecue rotation (BBQ) was used for treating lateral canal BPPV with geotropic nystagmus in 95.3% of respondents. Extreme variation was noted for therapeutic approach of lateral canal BPPV with ageotropic nystagmus BBQ, with 4 kinds of ORM and adjunctive measures to liberate otolith from cupula, while BBQ was again the most commonly used ORM (76.7%). CONCLUSION: The development of practical and efficient ORM for lateral canal BPPV with ageotropic nystagmus is necessary.

Delayed Electrode Extrusion after Cochlear Implant Repositioning / 대한이비인후과학회지

It is well known that cochlear implant device repositioned in the posterosuperior direction will cause intracochlear electrode extrusion. We have recently repositioned a cochlear implant device due to infection and device exposure. The device repositioning was performed under C-arm assisted fluoroscopic monitoring. The exposed device was covered with a local scalp flap. During and immediately after the repositioning operation, electrodes seemed to be well positioned in place. Mapping and neural response imaging were performed 4 days after the operation, and the results were quite similar to the preoperative results. But when the same tests were performed one month after repositioning operation, we found that the number 15 and 16 electrodes were not responsive. The transorbital view also revealed a slight extrusion of the intracochlear electrode. In the present article, we discuss the possible cause of delayed electrode extrusion and its clinical implication.

Audiological and Clinical Finding of Eosinophilic Otitis Media in Korea / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Eosinophilic otitis media (EOM) is characterized by the presence of a highly viscous effusion containing eosinophils. It mainly occurs in patients with bronchial asthma, nasal polyps and is resistant to conventional treatments for otitis media. In these patients, steroid is very effective in controlling the disease. However, the major complication is sensorineural hearing loss, especially at high frequencies, which may occur despite steroid therapy. SUBJECTS AND METHOD: Here we report 10 cases of EOM at Seoul National University Hospital. Clinical courses and characteristics of the patients were analyzed. We compared the hearing deterioration and other clinical variables between EOM patients and age-matched non-EOM chronic otitis media patients. RESULTS: All cases had viscous effusion and 9 cases were associated with asthma and nasal polyps. All patients had a decreased hearing in high frequency range compared to the age matched controls. The average bone conduction threshold difference at 2 kHz, 4 kHz was 22.4 dB HL and 42.5 dB HL, respectively. Among the patients, one showed profound sensorineural hearing loss bilaterally after the onset of EOM and received cochlear implantation. The open set sentence score was 82% 6 months after cochlear implantation. Most of the cases were resistant to conventional treatments for otitis media, such as administration of antibiotic agents, ventilation tube insertion or mastoidectomy. However, cases that were given steroid treatment had improvement in ear symptoms. CONCLUSION: Since EOM patients show deterioration of hearing, it is important to properly diagnose EOM, start adequate treatment and explain to patients that the disease may last for a long period and progressive hearing loss may occur.

Clinical Manifestation and Prognosis of Vestibular Migraine According to the Vestibular Function Test Results

BACKGROUND AND OBJECTIVES: According to previous reports, patients with vestibular migraine (VM) display variable results from vestibular function tests (VFT): central, peripheral, or normal. The aim of this study was to classify the VM patients into the three groups according to interictal VFT findings (central, peripheral or normal) and to clarify the relationship between VFT results and the clinical manifestations and prognosis in each group. SUBJECTS AND METHODS: We reviewed the medical records of 81 patients diagnosed as VM using the criteria of Neuhauser, et al. between December 2004 and June 2009. Patients were divided into three groups according to the results of VFT. We compared the clinical manifestations and prognosis between groups. Characteristics including dizziness, the nature of headache, associated otologic symptoms, hearing threshold, duration of illness, and recovery time were analyzed. RESULTS: The number of patients with central, peripheral vestibular dysfunction and normal finding in VFT were 15, 28, and 38 respectively. There were no significant differences in the nature of headache, associated otologic symptoms, hearing threshold, duration of illness, and recovery time. A small difference was observed in the mean age and characteristics of dizziness, but these were not significant. CONCLUSIONS: In patients with VM, classification according to the type of vestibular dysfunction was not helpful in the prediction of prognosis and clinical manifestations.