Unexplained Sensorineural Hearing Loss Research Articles

A Preliminary Study on the Potential Mechanism of Notch Signaling Pathway in the Regulation of Sudden Sensorineural Hearing Loss

Sudden sensorineural hearing loss (SSHNL) is a sudden onset of unexplained sensorineural hearing loss. Studies have shown that the number of patients with SSNHL is increasing year by year, and the average age is decreasing, which seriously affects the quality of life of patients. Its pathogenesis is complex and the mechanisms of hearing loss caused by various causes are quite different, but no matter what the cause is, it is ultimately related to the damage and loss of the inner ear structural hair cells (HCs) and their associated spiral ganglion cells (SGCs). Studies have shown that the Notch signaling pathway can regulate the development of the inner ear and nervous system in mammals. Hes family, Math1, DNER, Wnt signaling, and the lateral induction and lateral inhibition of Notch signaling related to the Notch signaling pathway are all key factors for the differentiation and development of HCs and SGCs. Based on the existing research, this paper makes a comprehensive and systematic summary, summarizes the importance of HCs and their afferent partner SGCs in SSNHL, and the relationship between Notch signaling pathway and the existence of the two, to provide a reference for clinical treatment of SSNHL in the future.

Analysis of thyroid dysfunction in patients with sudden sensorineural hearing loss.

BackgroundSudden sensorineural hearing loss (SSHL) refers to the sudden occurrence of unexplained sensorineural hearing loss. The present study showed that different systemic diseases had different influence on the occurrence and hearing outcome of SSHL. Thyroid hormone is one of the important factors for the development of fetal ear and auditory function. However, the distribution of thyroid dysfunction in SSHL patients and the effect of thyroid dysfunction on the occurrence and hearing outcome of SSHL has not been studied.MethodsIn this study, a retrospective analysis had been done in 676 patients with SSHL. We had described the distribution of thyroid function in patients with SSHL in detail, and by the statistical method, analyzed the relationship between the hearing outcome and thyroid dysfunction, respectively.ResultsIn all patients, 24.41% (165/676) had abnormal thyroid function testing results. The onset age of SSHL in FT3 abnormal group (including low and high group) was younger than that in normal FT3 group. Recovery group had more patients with lower-than-normal T3 level as compared to non-recovery patients. Significant associations between T3 levels and hearing outcome were observed in the subgroup with longer time elapse between symptom onset and treatment (≥14 d).ConclusionThe incidence of thyroid dysfunction in SSHL is significantly higher than in the general population. There was obvious relationship between T3 and FT3 item of thyroid dysfunction and the onset time and hearing outcome of SSHL, which indicated that T3 or FT3 indicator may be one of the affecting factors for the SSHL. Early screening and diagnosis of thyroid dysfunction, especial T3 level, may help to evaluate the prognosis in SSHL patients.

Analysis of archived newborn dried blood spots (DBS) identifies congenital cytomegalovirus as a major cause of unexplained pediatric sensorineural hearing loss

PurposeCongenital cytomegalovirus (cCMV) infection is the most common non-genetic cause of sensorineural hearing loss (SNHL). However, accurate diagnosis of cCMV as the etiology of SNHL is problematic beyond the neonatal period. This study therefore examined whether cCMV infection could be identified retrospectively in children presenting with unexplained SNHL to a multidisciplinary diagnostic outpatient otolaryngology clinic at an academic medical center in Minnesota. MethodsOver a 4-year period, 57 patients with an age range of 3months to 10years with unexplained SNHL were recruited to participate in this study. Informed consent was obtained to test the archived dried blood spots (DBS) of these patients for cCMV infection by real-time PCR, targeting a highly conserved region of the CMV UL83 gene. Results were normalized to recovery of an NRAS gene control. Chart review was conducted to identify subjects who underwent genetic testing and/or neurodiagnostic imaging to investigate possible genetic, syndromic, or anatomical causes of SNHL. ResultsIn total, 15 of the 57 children with unexplained SNHL tested positive for CMV DNA in their DBS (26%). A mean viral load of 8.3×104 (±4.1×104) [range, 1×103–6×105] copies/μg DNA was observed in subjects retrospectively diagnosed with cCMV. No statistically significant correlation was found between viral load and SNHL severity. ConclusionsA retrospective DBS analysis demonstrated that 26% of patients presenting with unexplained SNHL in childhood had cCMV. DBS testing is useful in the retrospective diagnosis of cCMV, and may provide definitive diagnostic information about the etiology of SNHL.

Dispersive liquid–liquid microextraction (DLLME) optimization for determination of designer drugs (cathinones) and drugs abuse in oral fluid

Congenital cytomegalovirus (cCMV) infection is the most common non-genetic cause of sensorineural hearing loss (SNHL). However, accurate diagnosis of cCMV as the etiology of SNHL is problematic beyond the neonatal period. This study therefore examined whether cCMV infection could be identified retrospectively in children presenting with unexplained SNHL to a multidisciplinary diagnostic outpatient otolaryngology clinic at an academic medical center in Minnesota.Over a 4-year period, 57 patients with an age range of 3 months to 10 years with unexplained SNHL were recruited to participate in this study. Informed consent was obtained to test the archived dried blood spots (DBS) of these patients for cCMV infection by real-time PCR, targeting a highly conserved region of the CMV UL83 gene. Results were normalized to recovery of an NRAS gene control. Chart review was conducted to identify subjects who underwent genetic testing and/or neurodiagnostic imaging to investigate possible genetic, syndromic, or anatomical causes of SNHL.In total, 15 of the 57 children with unexplained SNHL tested positive for CMV DNA in their DBS (26%). A mean viral load of 8.3 × 104 (± 4.1 × 104) [range, 1 × 103–6 × 105] copies/μg DNA was observed in subjects retrospectively diagnosed with cCMV. No statistically significant correlation was found between viral load and SNHL severity.A retrospective DBS analysis demonstrated that 26% of patients presenting with unexplained SNHL in childhood had cCMV. DBS testing is useful in the retrospective diagnosis of cCMV, and may provide definitive diagnostic information about the etiology of SNHL.

Hipoaldosteronismo primario e hipoacusia bilateral moderada en un niño con una mutación sin sentido en homocigosis (Thr318Met) en el gen CYP11B2

Isolated congenital hypoaldosteronism is a rare disorder that presents as chronic salt-wasting syndrome during infancy. Aldosterone synthase deficiency due to mutations in CYP11B2 is the underlying cause in most cases. Apart from the classical electrolyte disturbances (hyponatremia and hyperkalemia), no other extra-adrenal features have been described to date. We report a male child with congenital hypoaldosteronism due to a homozygous missense mutation (Thr318Met) in CYP11B2 who also presented with unexplained sensorineural hearing loss.

Congenital cytomegalovirus: association between dried blood spot viral load and hearing loss

Aim:To investigate the relation between cytomegalovirus (CMV) viral load on dried blood spots (DBS) from newborn biochemical screening (“Guthrie”) cards, and sensorineural hearing loss (SNHL) in congenital CMV.Design:Cross-sectional study with...

Fourth International Symposium on Molecular Diagnostics in Laboratory Medicine 2–4 May 2002

Congenital cytomegalovirus (cCMV) infection is the most common non-genetic cause of sensorineural hearing loss (SNHL). However, accurate diagnosis of cCMV as the etiology of SNHL is problematic beyond the neonatal period. This study therefore examined whether cCMV infection could be identified retrospectively in children presenting with unexplained SNHL to a multidisciplinary diagnostic outpatient otolaryngology clinic at an academic medical center in Minnesota.Over a 4-year period, 57 patients with an age range of 3 months to 10 years with unexplained SNHL were recruited to participate in this study. Informed consent was obtained to test the archived dried blood spots (DBS) of these patients for cCMV infection by real-time PCR, targeting a highly conserved region of the CMV UL83 gene. Results were normalized to recovery of an NRAS gene control. Chart review was conducted to identify subjects who underwent genetic testing and/or neurodiagnostic imaging to investigate possible genetic, syndromic, or anatomical causes of SNHL.In total, 15 of the 57 children with unexplained SNHL tested positive for CMV DNA in their DBS (26%). A mean viral load of 8.3 × 104 (± 4.1 × 104) [range, 1 × 103–6 × 105] copies/μg DNA was observed in subjects retrospectively diagnosed with cCMV. No statistically significant correlation was found between viral load and SNHL severity.A retrospective DBS analysis demonstrated that 26% of patients presenting with unexplained SNHL in childhood had cCMV. DBS testing is useful in the retrospective diagnosis of cCMV, and may provide definitive diagnostic information about the etiology of SNHL.

Effects of platelet activating factor on the tubotympanic mucosa and inner ear in the guinea pig.

The effect of platelet activating factor (PAF) was studied to elucidate its role in the pathogenesis of otitis media and sensorineural hearing loss. The PAF alone did not induce a reduction of ciliary activity of the cultured middle ear mucosa. However, a dose-dependent decrease in ciliary activity was observed in the presence of the medium containing both PAF and macrophages. Intravenous injection of PAF did not induce dysfunction of the mucociliary system or morphologic changes of epithelium in the tubotympanum, but cytoplasmic vacuolization and ballooning were observed in the inner ear within 1 hour after injection of PAF. In contrast, intratympanic injection of PAF induced mucociliary dysfunction and some pathologic changes in the tubotympanum. Intratympanic inoculation of PAF induced no pathologic findings in the inner ear. These results suggest that PAF is at least partially involved in the pathogenesis of certain middle ear diseases such as otitis media with effusion. Additionally, PAF might be involved in the pathogenesis of some types of unexplained sensorineural hearing loss.

Aplasia and hypoplasia of the vestibulocochlear nerve: diagnosis with MR imaging.

To introduce aplasia or hypoplasia of the vestibulocochlear nerve (VCN) as a possible cause of hearing loss and to identify the magnetic resonance (MR) imaging characteristics of this entity. In seven patients with congenital deafness or unexplained sensorineural hearing loss, MR imaging enabled diagnosis of aplasia or hypoplasia of the VCN. Axial (0.7-mm) three-dimensional Fourier transformation-constructive interference in steady state (3DFT-CISS) images and parasagittal reconstruction images perpendicular on the course of the VCN were obtained. Twenty normal inner ears were also studied; their findings were compared with those of the patients. The facial nerve and inferior and superior vestibular and cochlear branches of the VCN were identified on the MR images in the 20 normal inner ears. Aplasia of the VCN was detected in two patients with normal labyrinths but with a severe stenosis of the internal auditory canal. A common VCN with absence of the cochlear branch was found bilaterally in two patients with a congenital malformation of the labyrinth. A common VCN with absence or hypoplasia of the cochlear branch was found in three patients with normal internal auditory canals and labyrinths. Submillimetric gradient-echo images (eg, 3DFT-CISS) should always be used to exclude aplasia or hypoplasia of the cochlear branch of the VCN in all cochlear implant candidates and patients with congenital deafness. This entity, which can occur with or without associated labyrinthine malformation, should be confirmed in two planes.

Congenital perilymphatic fistula: a prospective study in infants and children.

A 3-year prospective study of 244 children (aged 5 months to 17 years) with sensorineural hearing loss of unknown cause revealed that 57 children (23%) had radiographic evidence of abnormalities of the temporal bone, detected by computed tomography scan, and/or progression of sensorineural hearing loss. Of these 57 children, 42 (74%) underwent surgical exploration, with 15 children (26%) of this subgroup demonstrating active congenital perilymphatic fistula. The prevalence of congenital perilymphatic fistula in a large, closely monitored population of children with unexplained sensorineural hearing loss appears to be at least 6% (15 of 244 children). The incidence may be higher because some congenital perilymphatic fistulae may leak intermittently and not be observed during middle ear surgery. Therefore, in children with suspected sensorineural hearing loss, early and frequent audiological evaluations should be made to rule out progressive/fluctuating sensorineural hearing loss. These children should also have radiographic imaging of their temporal bone by computed tomography scan. The use of both methods is the best indicator for congenital perilymphatic fistula.