Visualization of endolymphatic hydrops using Magnetic Resonance Imaging after intratympanic Gd-DTPA administration in patients with Meniere’s disease

BACKGROUND and OBJECTIVES: Endolymphatic hydrops are known as major causes of Meniere's disease. MRI (Magnetic resonance imaging) with contrast tried recently makes it possible to visualize perilymphatic and endolymphatic space without invasive procedures. There are no tryouts in the interior of our country. We attempted MRI after injection of gadolinium-diethylen-triamine pentaacetic acid (Gd-DTPA) in normal adults and patients with Meniere's disease to make sure 3D-FLAIR (fluid-attenuated inversion recovery) MRI parameters and to visualize endolymphatic spaces. MATERIALS and METHODS: Five normal adults and Five patients with Meniere's disease were included in this study. Twenty-four hours after Gd-DTPA intratympanic injection, we performed 3D-FLAIR and 3D-IR imaging at 3T. MRI region of interest signal intensity was used to determine the diffusion of Gd-DTPA into the perilymphatic fluid spaces over time. RESULTS: Five of five in normal group, using 3D-IR MRI after Gd injection, had enhanced imagings (perilymphatic spaces) of inner ears. Five of five in patients group, using 3D-IR after Gd injection, had enhanced perilymphatic spaces and non-enhanced endolymphatic hydrops. CONCLUSIONS: Delayed contrast imaging of the inner ear with 3D-IR MRI after Gd-DTPA intratympanic injection revealed in vivo visualization of endolymphatic hydropsope

쥐에서 비타민A 결핍이 노화 관련 및 소음 유발 감각신경성 난청에 미치는 영향

Dept. of Medicine/박사Vitamin A deficiency (VAD) causes a variety of pathologic phenotypes such as skin differentiation, spermatogenesis, and immune system function in human and animal subjects. VAD has also been reported to induce hearing impairment, yet its underlying mechanism is still unclear. In the present study, I evaluated the effect of VAD on hearing function using a mouse model of VAD. The hearing ability was evaluated with auditory brainstem responses (ABR) in two mouse strains: ICR (albino type) and C57BL/6 (pigmented type). For each strain, mice were divided into two groups as follows: group 1 (VAD group) was fed a purified vitamin A-free diet from 7 days after pregnancy and group 2 (control group) was fed a normal diet. Hearing thresholds was measured by ABR from 3 weeks until 20 weeks after birth. After serum levels of retinoic acid in VAD group reached less than a half of those in control group, only albino VAD group showed significant increase in hearing thresholds, compared to those of other groups (albino control group and both groups of pigmented mice) (p<.05). When identifying the histopathology in albino mice, the results were closely correlated with the changes in hearing thresholds with aging. However, when noise was applied to the pigmented strain, pigmented VAD mice showed poorer recovery of auditory thresholds after noise exposure than pigmented control mice. In conclusion, hearing thresholds of VAD mice were impaired by aging and noise insult when compared to other groups, although cochlear melanocytes might play some protective roles in pigmented VAD mice. These results suggest that VAD may cause age-related hearing loss and also affect the recovery of noise-induced hearing loss in mice.ope

Progressive hearing loss in vitamin A-deficient mice which may be protected by the activation of cochlear melanocyte

Vitamin A deficiency (VAD) produces various pathologic phenotypes in humans and animals. However, evidence regarding the effect of VAD on hearing function has been inconsistent. In this study, we evaluated the effect of VAD on hearing function in two mouse models of VAD. Hearing ability was evaluated on the basis of auditory brainstem response from 3 to 20 weeks after birth in C57BL/6 (pigmented) and imprinting control region (albino) mice. The two mice strains were divided into the VAD (purified vitamin A-free diet from 7 days after pregnancy) and control (normal diet) groups. Albino VAD mice exhibited hearing loss after 6 weeks and became deaf at 18 weeks. Histological findings revealed degenerative changes in outer hair cells and neuronal loss in the spiral ganglion in albino VAD mice. In contrast, pigmented VAD mice, except those with middle-ear infection, showed no significant hearing loss. Interestingly, pigmented VAD mice exhibited melanocyte activation in the stria vascularis and upregulation of tyrosinase. Recovery of hearing after noise exposure was poorer in pigmented VAD mice than in control mice. In conclusion, complete VAD might be related to age-related or noise-induced hearing loss in mice, protection against which might involve melanocyte activation.This research was supported by the Bio &amp;amp; Medical Technology Development Program of the National Research Foundation (NRF) funded by the Korean government (MSIP&amp;amp;MOHW) (No. 2016M3A9B5941215) and the Bio &amp;amp; Medical Technology Development Program of the National Research Foundation (NRF) funded by the ministry of Science, ICT &amp;amp; Future Planning (NRF-2014M3A9D5A01073865)

Severe to profound hearing loss in patients with progressed Alport's syndrome

CONCLUSION: The concept of hearing loss severity must be redefined, as there is a clear need for more active hearing management in Alport's syndrome patients with severe and profound hearing loss. OBJECTIVES: Sensorineural hearing loss (SNHL) caused by Alport's syndrome generally does not exceed 60-70 dB, because a cochlear lesion is responsible for this hearing loss. Careful management of renal function improves the prognosis and the longevity of Alport's syndrome patients; it is useful to reassess SNHL caused by Alport's syndrome. PATIENTS AND METHODS: Thirty-two patients with Alport's syndrome were analyzed retrospectively. Pure tone audiograms (PTAs), speech audiograms, and transiently evoked otoacoustic emissions (TEOAEs) were performed. Hearing loss severity was compared to duration of disease and severity of renal dysfunction. We also evaluated the correlation between OAEs and PTAs according to the hypothesis that evoked OAEs would be abnormal even in early stage SNHL in Alport's syndrome. RESULTS: The level of hearing was positively correlated with disease duration. The hearing of the end-stage renal disease (ESRD) group, whose hearing threshold could exceed 70 dB, was worse than that of the non-ESRD group. OAEs were found in patients with normal hearing and mild hearing loss and had no significant early detection value.ope

Useful surgical techniques for facial nerve preservation in tumorous intra-temporal lesions

The management of the facial nerve in tumorous temporal lesions is particularly challenging due to its complex anatomic location and potential postoperative complications, including permanent facial paralysis. The most important concern regarding surgical treatment of a tumorous temporal lesion is the inevitable facial paralysis caused by nerve injury during the tumor removal, especially in patients with minimal to no preoperative facial nerve dysfunction. We describe successful four cases in which various surgical techniques were developed for the preservation of the facial nerve in treatment of intratemporal tumorous lesionsope

The effect of surgical timing on functional outcomes of traumatic facial nerve paralysis

BACKGROUND: The optimal timing for surgical exploration of traumatic facial paralysis to best preserve facial function is currently controversial. This article reviews the final outcomes of facial function in patients with traumatic intratemporal facial nerve injury according to the timing of surgical exploration. METHODS: We performed a retrospective review of 58 patients with complete facial nerve paralysis caused by temporal bone fractures as a result of head trauma between 1998 and 2007. Patients were divided into three groups according to the type of trauma. The only difference between patients in each group was the timing of the surgical exploration. Characteristics assessed in the study included type of trauma, location of facial nerve injury, timing of surgical intervention, audiometric findings, surgical approach, and long-term follow-up of recovery of facial nerve function, as assessed by two facial nerve grading systems. RESULTS: The final functional gains in early-operated patients were 3.7 +/- 0.59 on the House-Brackmann (HB) scale and 75.6 +/- 10.88 on the Sunnybrook scale. The outcome in late-operated patients was 2.17 +/- 0.52 on the HB scale and 34.7 +/- 16.95 on the Sunnybrook scale, and that of nonoperated patients was 2.0 +/- 0.63 on the HB scale and 26.8 +/- 6.27 on the Sunnybrook scale. CONCLUSION: This study demonstrated that some patients with traumatic facial nerve paralysis who had nerve conduction studies consistent with a poor prognosis regained considerable facial function after early surgical intervention. However, late exploration after facial nerve paralysis did not result in positive outcomes, regardless of the type of temporal bone fracture or the site of injury, and no difference was observed compared with conservative treatment.ope

Pou3f4 deficiency causes defects in otic fibrocytes and stria vascularis by different mechanisms

DFN3, the most prevalent X-linked hearing loss, is caused by mutations in the POU3F4 gene. Previous studies in Pou3f4 knockout mice suggest that defective otic fibrocytes in the spiral ligament of the cochlear lateral wall may underlie the hearing loss in DFN3. To better understand the pathological mechanisms of the DFN3 hearing loss, we analyzed inner ears of Pou3f4-deficient mice during development. Our results indicate that compartmentalization of the spiral ligament mesenchyme setting up boundaries for specific otic fibrocytes occurs normally in Pou3f4-deficient cochlea. However, differentiation of the compartmentalized mesenchyme into specific otic fibrocytes was blocked in the absence of Pou3f4 function. In addition, we found that stria vascularis in the cochlear lateral wall was also affected in Pou3f4-deficient cochlea. Unlike the otic fibrocytes, differentiation of stria vascularis was completed in the absence of Pou3f4 function, yet expression of Kir4.1 channels in the strial intermediate cells, essential for the sound transduction, was lost afterwards. These results suggest that Pou3f4 deficiency causes defects in both otic fibrocytes and stria vascularis at different developmental stages and by different pathological mechanisms, which may account for the progressive nature of DFN3 hearing loss.ope