Validation of operational definitions of mortality in a nationwide hemodialysis population using the HealthInsurance Review and Assessment Service databases of Korea

Health Insurance Review and Assessment Service’s (HIRA) claims data have been used in studies of hemodialysis patients even though information about mortality is not provided in this database. Mortality analysis using HIRA data has been conducted using various operational definitions that have not been validated. This study aimed to validate operational definitions of mortality for maintenance hemodialysis patients that have been used when analyzing the Korean HIRA database. Methods: This study utilized claims data of the Korean National Health Insurance Service (NHIS) between January 2008 and December 2019. We estimated mortality based on operational definitions applied in previous studies using the HIRA database and compared it with NHIS mortality information to validate accuracy. Results: A total of 128,876 patients who started maintenance hemodialysis between January 2009 and December 2019 were analyzed. The accuracy of estimated mortality was the highest at 96% in the group where mortality was defined as an absence of claims data for 150 days. If the period of no claims data was set to 90 days or less, there was a risk of overestimating the mortality for the entire study period. When it was set to 180 days or more, there was a risk of underestimating the mortality, as the follow-up time was close to the end of the study period. Conclusion: When mortality analysis of maintenance hemodialysis patients is performed using HIRA data, it is most accurate to set the operational definition period as the absence of claims data for 150 days.

Verbal Auditory Agnosia Developed after Unilateral Temporal Lobe Infarction / 대한이비인후과학회지

Stroke results in sudden loss of function related to its damaged portion. When this occurs in temporal lobe, the function of hearing and listening may be affected, although receptive language processing is affected while hearing perception is relatively spared. This is called as “central deafness.” It has been known that hearing ability is seldom impaired in the case of temporal lobe stroke except in the case of bilateral lesions. However, we experienced a 72-year-old, right-handed woman who presented with both sudden hearing difficulty due to unilateral temporal lobe infarctions after suddenly not being able to respond to any verbal questions except environmental sounds. Pure-tone audiometry showed both flat sensorineural hearing loss of mild degree in both ears but she could not understand any verbal sound. Brain MRI demonstrated extensive ischemic infarcts in the left temporal lobes involving primary auditory cortex. She was diagnosed as verbal auditory agnosia and has received speech-language therapy.

Therapeutic Efficacy of the Modified Epley Maneuver With a Pillow Under the Shoulders

Objectives@#. Canalolithiasis of the posterior semicircular canal (PC) is the most common reason for benign paroxysmal positional vertigo (BPPV). If a patient is diagnosed with PC-BPPV through the Dix-Hallpike test, the modified Epley maneuver (mEpley) is used as the gold standard treatment. To reduce the discomfort of the standard mEpley, we proposed placing a pillow under the shoulders during this therapeutic maneuver. The purpose of this study was to determine whether the therapeutic efficacy of the mEpley with a pillow under the shoulders (mEpley-PS) was comparable to that of the standard mEpley. @*Methods@#. A randomized controlled study at three academic referral hospitals was conducted in compliance with the CONSORT statement. Patients who were diagnosed with PC-BPPV through the Dix-Hallpike test were randomly assigned to groups A or B. Patients in groups A and B were treated with the standard mEpley and mEpley-PS, respectively. The resolution of vertigo and nystagmus on the Dix-Hallpike test at a 1-week follow-up after treatment was the main outcome measurement to assess the efficacy of treatment. @*Results@#. Forty-one patients diagnosed with PC-BPPV were enrolled in this study. Twenty-one patients were assigned to group A and 20 were assigned to group B. The success rate at 1 week after treatment was 85.7% in group A and 80.0% in group B. There was no statistically significant difference between the two groups (P=0.697). @*Conclusion@#. The therapeutic efficacy of the mEpley-PS was comparable to that of the standard mEpley. The use of the pillow modification may be an excellent alternative if a patient cannot tolerate the head-hanging position, and it is helpful for patients who have anxiety about the head-hanging position. The mEpley-PS can be performed on a bed with or without a headboard. It is both a patient-friendly and a clinician-friendly maneuver.

Novel Antihypertension Mechanism of β-Glucan by Corin and ANP-Mediated Natriuresis in Mice

Many of the β-glucans are known to have antihypertensive activities, but, except for angiotensin-converting enzyme II inhibition, the underlying mechanisms remain unclear. Corin is an atrial natriuretic peptide (ANP)-converting enzyme. Activated corin cleaves pro-ANP to ANP, which regulates water–sodium balance and lowers blood pressure. Here, we reported a novel antihypertensive mechanism of β-glucans, involved with corin and ANP in mice. We showed that multiple oral administrations of β-glucan induced the expression of corin and ANP, and also increased natriuresis in mice. Microarray analysis showed that corin gene expression was only upregulated in mice liver by multiple, not single, oral administrations of the β-glucan fraction of Phellinus baumii (BGF). Corin was induced in liver and kidney tissues by the β-glucans from zymosan and barley, as well as by BGF. In addition to P. baumii, β-glucans from two other mushrooms, Phellinus linteus and Ganoderma lucidum, also induced corin mRNA expression in mouse liver. ELISA immunoassays showed that ANP production was increased in liver tissue by all the β-glucans tested, but not in the heart and kidney. Urinary sodium excretion was significantly increased by treatment with β-glucans in the order of BGF, zymosan, and barley, both in 1% normal and 10% high-sodium diets. In conclusion, we found that the oral administration of β-glucans could induce corin expression, ANP production, and sodium excretion in mice. Our findings will be helpful for investigations of β-glucans in corin and ANP-related fields, including blood pressure, salt–water balance, and circulation.

Nonshaved Ear Surgery: Effect of Hair on Surgical Site Infection of the Middle Ear/Mastoid Surgery and Patients' Preference for the Hair Removal

BACKGROUND AND OBJECTIVES: This study aimed 1) to compare the rates of surgical site infection (SSI) between two groups with and without preoperative hair shaving, 2) to compare the bacterial colonization just before the skin incision between them, and 3) to evaluate people’s preference for the hair shaving. SUBJECTS AND METHODS: The retrospective study enrolled cases in which middle ear and mastoid surgery was performed with as well as without hair removal. Main measurement outcomes were the SSI rate within 3 months following the surgery, bacterial culture results obtained from the incision area just before the skin incision, and questionnaire to evaluate the preference for hair shaving from patients with chronic suppurative otitis media but without experience with the ear surgery. RESULTS: This study did not show any difference in the rates of SSI and bacterial colonization between two groups with and without preoperative hair shaving. Most patients without experience with the ear surgery chose the nonshaved ear surgery, even though the questionnaire presented a comment as follow; “Your hair will always grow back as the growth speed of about 1.25 cm per month.” CONCLUSIONS: There is no evidence showing that preoperative shaving of the surgical site is helpful for the SSI than no hair removal. Nonshaved middle ear and mastoid surgery via postauricular approach appears to be preferable. Contrary to doctors’ popular belief, the hair shaving can cause psychological discomfort, especially for women. Now is the time to keep the balance between the professional’s perspective and the patients’ preferences.

Changing Disease Trends in the Northern Gyeonggi-do Province of South Korea from 2002 to 2013: A Big Data Study Using National Health Information Database Cohort

OBJECTIVES: To investigate the chronological patterns of diseases in Northern Gyeonggi-do province, South Korea, and compare these with national data. METHODS: A National Health Insurance cohort based on the National Health Information Database (NHID Cohort 2002–2013) was used to perform a retrospective, population-based study (46,605,433 of the target population, of which 1,025,340 were randomly sampled) to identify disease patterns from 2002 to 2013. Common diseases including malaria, cancer (uterine cervix, urinary bladder, colon), diabetes mellitus, psychiatric disorders, hypertension, intracranial hemorrhage, bronchitis/bronchiolitis, peptic ulcer, and end stage renal disease were evaluated. RESULTS: Uterine cervix cancer, urinary bladder cancer and colon cancer had the greatest rate of increase in Northern Gyeonggi-do province compared with the rest of the country, but by 2013 the incidence of these cancers had dropped dramatically. Acute myocardial infarction and end stage renal disease also increased over the study period. Psychiatric disorders, diabetes mellitus, hypertension and peptic ulcers showed a gradual increase over time. No obvious differences were found for intracranial hemorrhage or bronchitis/bronchiolitis between the Northern Gyeonggi-do province and the remaining South Korean provinces. Malaria showed a unique time trend, only observed in the Northern Gyeonggi province, peaking in 2004, 2007 and 2009 to 2010. CONCLUSION: This study showed that the Northern Gyeonggi-do province population had a different disease profile over time, compared with collated data for the remaining provinces in South Korea. “Big data” studies using the National Health Insurance cohort database can provide insight into the healthcare environment for healthcare providers, stakeholders and policymakers.

Prevalence and risk factors for reduced pulmonary function in diabetic patients: The Korea National Health and Nutrition Examination Survey

BACKGROUND/AIMS: An association between reduced pulmonary function and diabetes has been observed. Our aim was to evaluate the prevalence and risk factors associated with reduced pulmonary function in diabetic patients. METHODS: We analyzed data from the Korea National Health and Nutrition Examination Survey 2011 to 2013. The study population included data from 8,784 participants (including 1,431 diabetics) aged ≥ 40 years. Reduced pulmonary function was defined as patients with restrictive (forced expiratory volume in 1 second/forced vital capacity [FEV₁/FVC] ≥ 0.7 and FVC < 80% of predicted value) or obstructive (FEV₁/FVC < 0.7) patterns. RESULTS: Subjects with diabetes had a higher prevalence of restrictive (18.4% vs. 9.4%, p < 0.001) and obstructive impairments (20% vs. 12.6%, p < 0.001) than those without diabetes. The adjusted odds ratios (aORs) (95% confidence interval [CI]) for obstructive and restrictive pulmonary impairment were 0.91 (0.75 to 1.11) and 1.57 (1.30 to 1.89), respectively. In the diabetes population, age (aOR, 1.04; 95% CI, 1.02 to 1.06), male sex (aOR, 1.40; 95% CI, 1.04 to 1.88), and body mass index (aOR, 1.15; 95% CI, 1.10 to 1.21) were independently associated with restrictive pulmonary impairment. Age (aOR, 1.12; 95% CI, 1.09 to 1.14), male sex (aOR, 4.24; 95% CI, 2.42 to 7.44), and smoking at any point (ever-smoker: aOR, 1.96; 95% CI, 1.16 to 3.33) were independent risk factors for obstructive pulmonary impairment in diabetics. Diabetes duration or glycated hemoglobin had no association with pulmonary impairment in diabetes. CONCLUSIONS: Subjects with diabetes had a higher risk of restrictive pulmonary impairment than those without diabetes after adjusting for confounding factors. Older age, male sex, body mass index, and smoking were associated with reduced lung function in diabetes.

Clinical Characteristics of Idiopathic Epidermoid and Dermoid Cysts of the Ear

BACKGROUND AND OBJECTIVES: Epidermoid and dermoid cysts are benign cystic lesions, lined by ectodermal squamous epithelium. They are not common in the head and neck areas, which constitute ~7% of all cases of epidermoid and dermoid cysts. The aim of this study was to investigate the clinical characteristics of epidermoid and dermoid cysts that developed around the ear. SUBJECTS AND METHODS: The clinical records were retrospectively reviewed for patients confirmed histologically as idiopathic epidermoid and dermoid cysts of the ear from January 2011 to December 2015. RESULTS: Total 15 cases consisted of 14 epidermoid cysts and only 1 dermoid cyst. There were 11 males and 4 females (mean age of 37.8±16.8 years old). Right side was 7 cases and left was 8. The cyst was located at the lobule in 4 cases, at the ear canal in 4 cases, at the preauricular area in 4 cases, and at the postauricular area in 3 cases. In cases of epidermoid cysts, there was no significant difference in age, sex, and size according to the location. Patients with cysts on helix were younger than others. CONCLUSIONS: This study demonstrated that most cutaneous cysts developing around the ear were epidermoid cysts and there was no site preference for occurrence of epidermoid cysts.

Prevalence and risk factors of periodontitis among adults with or without diabetes mellitus

BACKGROUND/AIMS: This study examined prevalence and risk factors of periodontitis in representative samples of Korean adults, with and without diabetes mellitus (DM). METHODS: Data from the 2012 Korean National Health and Nutritional Examination Survey were analyzed. A total of 4,477 adults (≥ 30 years old) were selected from 8,057 individuals who completed a nutrition survey, a self-reported general health behavior questionnaire, an oral examination, an oral hygiene behaviors survey, and laboratory tests. DM was defined as a fasting plasma glucose ≥ 126 mg/dL, or self-reported diagnosed diabetes, or current use of oral hypoglycemic agents and/or insulin. The community periodontal index was used to assess periodontitis status and comparisons between the periodontitis and the non-periodontitis group, were performed, according to the presence of DM. Risk factors for periodontitis in adults with DM and without DM were evaluated by multiple logistic regression analysis. RESULTS: The prevalence of periodontitis was significantly higher in adults with DM (43.7%) than in those without DM (25%, p < 0.001). In adults without DM, risk factors for periodontitis were older age, male, urban habitation, waist circumference, smoking, oral pain, and less frequent tooth brushing. Significant risk factors for periodontitis in adults with DM were the smoking, oral pain, and not-using an oral hygiene product. CONCLUSIONS: Adults with DM have an increased risk of periodontitis than those without DM. Current smoking and oral pain increase this risk. Using an oral hygiene product can reduce risk of periodontal disease in adults with DM.

Glomerular filtration rate affects interpretation of pulmonary function test in a Korean general population: results from the Korea National Health and Nutrition Examination Survey 2010 to 2012

BACKGROUND/AIMS: The pulmonary abnormalities (principally restrictive abnormalities) are characteristic of renal transplant recipients or those with end-stage renal disease. Our aim was to explore whether the prevalence of spirometric abnormalities was influenced by the estimated glomerular filtration rates (GFRs) in a Korean general population. METHODS: We used data obtained during the 2010 to 2012 Korean National Health and Nutrition Examination Survey, a national cross-sectional survey. We analyzed data from subjects for whom spirometric assays and estimated GFRs were of acceptable quality. RESULTS: A total of 8,809 subjects (3,868 male and 4,941 female) was included. In both males and females with GFR values < 60 mL/min/1.73 m², the linear trends toward the presence of obstructive and restrictive patterns were significant. However, the percent predicted forced vital capacity (FVC) decreased with a decline in the estimated GFR, but only in males (p for trend < 0.0031). Multivariate linear regression analysis showed a decline in the estimated GFR was independently associated with falls in the percent predicted FVC and the forced expiratory volume in 1 second/FVC ratio in both males and females. However, the percent predicted FVC was independently predictive only in males (p = 0.002). CONCLUSIONS: Impaired pulmonary function was associated with a decline in the estimated GFR. The percent predicted FVC decrease paralleled the decline in estimated GFR in male only. Careful interpretation of pulmonary function test data is required in patients with decreased GFRs or impaired renal function, especially males.

Clinical Efficacy of Electroneurography in Acute Facial Paralysis

The estimated incidence of acute facial paralysis is approximately 30 patients per 100000 populations annually. Facial paralysis is an extremely frightening situation and gives extreme stress to patients because obvious disfiguring face may cause significant functional, aesthetic, and psychological disturbances. For stressful patients with acute facial paralysis, it is very important for clinicians to answer the questions like whether or not their facial function will return to normal, how much of their facial function will be recovered, and how long this is going to take. It is also important for clinicians to treat the psychological aspects by adequately explaining the prognosis, in addition to providing the appropriate medical treatment. For decades, clinicians have used various electrophysiologic tests, including the nerve excitability test, the maximal stimulation test, electroneurography, and electromyography. In particular, electroneurography is the only objective measure that is useful in early stage of acute facial paralysis. In this review article, we first discuss the pathophysiology of injured peripheral nerve. And then, we describe about various electrophysiologic tests and discuss the electroneurography extensively.

Laparoscopic tube-preserving surgical procedures for ectopic tubal pregnancy

OBJECTIVE: To present our experience with laparoscopic tube-preserving surgery for ectopic tubal pregnancy and evaluate its feasibility and efficacy. METHODS: This was a prospective study of 57 consecutive patients with ectopic tubal pregnancies undergoing laparoscopic tube-preserving procedures including salpingotomy, salpingostomy, segmental resection and reanastomosis, and fimbrial milking. The outcome measures were treatment success rates and homolateral patency rates. RESULTS: Of the 57 surgical procedures, 55 (96.4%) were performed successfully without any additional intervention. The number of patients receiving salpingotomy, salpingostomy, segmental resection and reanastomosis, and fimbrial milking were 24 (42.1%), 25 (43.9%), 4 (7.0%), and 2 (3.5%), respectively. Two case was switched to salpingectomy because excessive bipolar coagulation was required to obtain hemostasis at the tubal bleeding bed. Over a mean β-human chorionic gonadotropin resolution time of 18.3±5.9 days, no persistent trophoblast or postoperative complications occurred. A tubal patency test using hysterosalpingography was performed in 15 cases at 3 months postoperatively. Among these, the homolateral tubal patency rate was 75% (11 of 15) and the contralateral patency rate was 80% (12 of 15). CONCLUSION: Tube-preserving surgery is a feasible and safe treatment option for ectopic tubal pregnancy. However, considering that the optimal goal of tube-preserving surgical procedures is not the treatment success, some caution is warranted in interpreting results of this study.

Disability of Hearing Impairment Is Positively Associated With Urine Albumin/Creatinine Ratio in Korean Adults: The 2011–2012 Korea National Health and Nutrition Examination Survey

OBJECTIVES: The aim of this study was to determine whether chronic kidney disease (CKD) is associated with hearing thresholds in the nationwide, large-scaled Korean population. METHODS: This study analyzed the data of 9,798 subjects of 19 years and older (4,387 males and 5,411 females). Urine albumin-to-creatinine ratio (ACR) was measured from first-voided spot urine samples. The air-conduction hearing threshold was measured at 0.5, 1, 2, 3, 4, and 6 kHz and pure tone audiogram (PTA) average was calculated as the four-frequency average of 0.5, 1, 2, and 4 kHz. RESULTS: Urine ACR was significantly correlated with the PTA average of better ear in both genders, especially at 3 and 6 kHz in males and at 1, 3, 4, and 6 kHz in females. After adjusting, urine ACR also increased the risk of hearing loss in female, especially if urine ACR was 30 mg/g and more (odds ratio, 1.636–2.229. This study showed that the degree of hearing loss was significantly different according to categories of urine ACR in both genders. Hearing loss without disability was found less but that with bilateral hearing disability was found more as urine ACR increased. In generally, prevalence of hearing loss with disability was higher in males than females. CONCLUSION: This study demonstrated that urine ACR was significantly correlated with the PTA average of better ear in Korean adults of both genders. This study suggests that clinicians should carefully monitor the hearing level for subjects with elevated urine ACR, even though high urine ACR within the normal range.

How do You Select an Anesthesia Method Prior to Tympanostomy Tube Insertion for a Child?

The use of general (face-mask inhalation and intravenous) anesthesia has been the method of choice for tympanostomy tube insertion in children. However, there is no exact guideline for the choice of anesthesia method and there is no evidence to support the use of one anesthesia method over another. Clinically, the anesthesia method used to be decided by old customs and the surgeon's blind faith that children cannot bear tympanostomy tube insertion under local anesthesia. Clinicians should keep in mind that pediatric anesthesia has a potential risk. Despite infrequent serious complications, their seriousness necessitates that sedation or general anesthesia should be done by an anesthesiologist and thus children requiring tympanostomy tube insertion should be referred to secondary or tertiary hospitals, even if they have been followed by a primary care physician for a long time. Previous evidence showed that local anesthesia is appropriate for tympanostomy tube insertion in selected children, especially in children older than 5 years are older. Proper choice of anesthesia method is helpful for both patient and medical service provider. Local anesthesia can give psychological relief to children and their parent. It is easier for the medical service providers to schedule the operation and allocate the medical resources in their hospital. Local anesthesia can reduce individual, social, and national burdens for the health care services.

Anatomical Factors Influencing Pneumatization of the Petrous Apex

OBJECTIVES: Aim of the present study was to define the relationship between petrous apex pneumatization and the nearby major anatomical landmarks using temporal bone computed tomography (CT) images. METHODS: This retrospective, Institutional Review Board-approved study analyzed CT images of 84 patients that showed normal findings bilaterally. Pneumatization of the petrous apex was classified using two methods. Eight parameters were as follows: angle between the posterior cranial fossa and internal auditory canal, Morimitsu classification of anterior epitympanic space, distance between the carotid canal and jugular bulb, distance between the cochlear modiolus and carotid canal, distance between the tympanic segment and jugular bulb, high jugular bulb, distance between the vertical segment and jugular bulb, and distance between the lateral semicircular canals and middle cranial fossa. RESULTS: There was a significant difference in Morimitsu classification of the anterior epitympanic space between the two classification methods. Poorly pneumatic upper petrous apices were distributed uniformly in three types of Morimitsu classification, but more pneumatic upper petrous apices were found more often in anterior type. Lower petrous apex was well pneumatized regardless of the types of anterior epitympanic space, but the largest amount of pneumatization was found more frequently in the anterior type of anterior epitympanic space. CONCLUSION: This study showed that there was no reliable anatomic marker to estimate petrous apex pneumatization and suggests that the pneumatization of the petrous apex may be an independent process from other part of the temporal bone, and may not be influenced by the nearby major anatomical structures in the temporal bone. In this study, the anterior type of anterior epitympanic space was found to be closely related to more well-pneumatized petrous apices, which implies that the anterior saccule of the saccus medius may be the main factor influencing pneumatization of the petrous apex.

Age as a Determinant to Select an Anesthesia Method for Tympanostomy Tube Insertion in a Pediatric Population

BACKGROUND AND OBJECTIVES: To evaluate the relationship between age and anesthesia method used for tympanostomy tube insertion (TTI) and to provide evidence to guide the selection of an appropriate anesthesia method in children. SUBJECTS AND METHODS: We performed a retrospective review of children under 15 years of age who underwent tympanostomy tube insertion (n=159) or myringotomy alone (n=175) under local or general anesthesia by a single surgeon at a university-based, secondary care referral hospital. Epidermiologic data between local and general anesthesia groups as well as between TTI and myringotomy were analyzed. Medical costs were compared between local and general anesthesia groups. RESULTS: Children who received local anesthesia were significantly older than those who received general anesthesia. Unilateral tympanostomy tube insertion was performed more frequently under local anesthesia than bilateral. Logistic regression modeling showed that local anesthesia was more frequently applied in older children (odds ratio=1.041) and for unilateral tympanostomy tube insertion (odds ratio=8.990). The cut-off value of age for local anesthesia was roughly 5 years. CONCLUSIONS: In a pediatric population at a single medical center, age and whether unilateral or bilateral procedures were required were important factors in selecting an anesthesia method for tympanostomy tube insertion. Our findings suggest that local anesthesia can be preferentially considered for children 5 years of age or older, especially in those with unilateral otitis media with effusion.

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.

How Does Speaking Clearly Influence Acoustic Measures? A Speech Clarity Study Using Long-term Average Speech Spectra in Korean Language

OBJECTIVES: To investigate acoustic differences between conversational and clear speech of Korean and to evaluate the influence of the gender on the speech clarity using the long-term average speech spectrum (LTASS). METHODS: Each subject's voice was recorded using a sound level meter connected to GoldWave program. Average long-term root mean square (RMS) of one-third octave bands speech spectrum was calculated from 100 to 10,000 Hz after normalizing to 70 dB overall level using the MATLAB program. Twenty ordinary Korean were compared with 20 Korean announcers with equal numbers of men and women in each group. RESULTS: Compared with the LTASS of ordinary men, that of ordinary women was lower at low frequencies, but higher at 630, 800, 1,600, 5,000, and 10,000 Hz. Compared with the LTASS of male announcers, that of female announcers was lower at low frequencies. Compared with the LTASS of ordinary men, that of male announcers was significantly lower at 100, 125, 200, and 250 Hz. Compared with the LTASS of ordinary women, that of female announcers was lower at 100, 125, 160, 200, 250, 500, and 10,000 Hz. The LTASS of announcer showed lower levels at 100, 200 Hz and higher at 500, 630, 800, and 1,000 Hz that that of ordinary Koreans. CONCLUSION: This study showed that the drop-off of the LTASS in the low frequency region might make the ratings of women and announcers more clearly than those of men and ordinary persons respectively. This drop-off in the low frequency might result in less upward spread of masking and clearer speech. This study reduced an error resulting from a wide variability of clear speech strategies and intelligibility gains, because this study recruited professional speakers. We hope that our results demonstrate the difference in acoustic characteristics of the speech of ordinary Korean persons.

Binaural Electric-Acoustic Interactions Recorded from the Inferior Colliculus of Guinea Pigs: The Effect of Masking Observed in the Central Nucleus of the Inferior Colliculus

OBJECTIVES: To investigate the electric-acoustic interactions within the inferior colliculus of guinea pigs and to observe how central masking appears in invasive neural recordings of the inferior colliculus (IC). METHODS: A platinum-iridium wire was inserted to scala tympani through cochleostomy with a depth no greater than 1 mm for intracochlear stimulation of electric pulse train. A 5 mm 100 microm, single-shank, thin-film, penetrating recording probe was inserted perpendicularly to the surface of the IC in the coronal plane at an angle of 30-40degrees off the parasagittal plane with a depth of 2.0-2.5 mm. The peripheral and central masking effects were compared using electric pulse trains to the left ear and acoustic noise to the left ear (ipsilateral) and to the right ear (contralateral). Binaural acoustic stimuli were presented with different time delays and compared with combined electric and acoustic stimuli. The averaged evoked potentials and total spike numbers were measured using thin-film electrodes inserted into the central nucleus of the IC. RESULTS: Ipsilateral noise had more obvious effects on the electric response than did contralateral noise. Contralateral noise decreased slightly the response amplitude to the electric pulse train stimuli. Immediately after the onset of acoustic noise, the response pattern changed transiently with shorter response intervals. The effects of contralateral noise were evident at the beginning of the continuous noise. The total spike number decreased when the binaural stimuli reached the IC most simultaneously. CONCLUSION: These results suggest that central masking is quite different from peripheral masking and occurs within the binaural auditory system, and this study showed that the effect of masking could be observed in the IC recording. These effects are more evident and consistent with the psychophysical data from spike number analyses than with the previously reported gross potential data.

The Past and Present of the Research on Cochlear Stem Cell / 대한이비인후과학회지

Hearing loss is the most frequent sensory deficit in the human population and can occur at any age. Hearing loss ranges from mild to profound, can be conductive, sensorineural or mixed type and may be congenital or acquired. Sometimes, some of hearing loss can be cured by medical or surgical interventions but most of hearing loss is irreversible and many patients struggle in their daily activities and their quality of life suffers. Although hearing aids as well as cochlear implants can give good solution to patients with a hearing loss that cannot be cured, both of them have some limitations and cannot solve the hearing problem perfectly. Recent scientific achievements in cochlear stem cell research and regenerative medicine can suggest ultimate solution to researchers as well as doctors and can give a hope to patients with a hearing loss and their family. Until now, mammalian cochlear hair cells have been known to be never replaced or regenerated, such that insults to the cochlea cause progressive and permanent hearing loss of variable degree. However, non-mammalian vertebrates are capable of replacing lost hair cells and have stem cells in their cochlea, which has recently led to efforts to understand the molecular and cellular basis of regenerative responses in different vertebrate species. In this article, I review the development of mammalian cochlea, focusing on the molecular events related with the development and regeneration. I also introduce the progress in overcoming the limits to mammalian cochlear hair cell regeneration and recent efforts to cochlear regenerative medicine.