Low-frequency Sensorineural Hearing Loss Research Articles

Distribution of Low-Frequency Nerve Fibers in the Auditory Nerve

Low-frequency cochlear fibers are on the outer surface of the auditory nerve adjacent to the vestibular nerve in the distal part of the internal auditory canal. There is a misconception that low-frequency cochlear fibers are in the core of the cochlear nerve and are surrounded by high-frequency fibers. We analyzed temporal bones with a loss of upper spiral ganglion cells caused by different etiologies (n = 6) and traced the corresponding fibers into the distal internal auditory canal. Spiral ganglion cells for each segment (I-IV) of the cochlea were counted, and we defined the location of nerve fibers from the various segments. There was total or near-total degeneration of the upper spiral ganglion cells in these bones. Corresponding low-frequency fibers were on the outer surface of the cochlear nerve adjacent to the vestibular nerve in the distal segment of the internal auditory canal. Low-frequency fibers seem to be located at the periphery of the cochlear nerve. These findings provide one possible explanation for the low-frequency sensorineural hearing loss found in 10% of patients with vestibular nerve schwannomas and may have clinical relevance in the diagnosis of these lesions.

Sensorineural Hearing Loss in Vogt‐Koyanagi‐Harada Syndrome

Vogt-Koyanagi-Harada (VKH) syndrome is a systemic condition characterized by ocular inflammatory disease as well as skin, ear, and meningeal manifestations. Patients with VKH often report tinnitus and hearing loss, but these symptoms tend to be given secondary consideration because most undergo treatment with steroids to prevent blindness resulting from granulomatous uveitis, exudative retinal detachment, and optic nerve inflammation. In the current retrospective review, 24 patients with this syndrome were screened for auditory system abnormalities. All patients denied history of noise exposure or ototoxic agent exposure. The age range of the patients was 13 to 42 years. Three patients reported tinnitus and two patients reported sudden hearing loss. One patient experienced vertigo and aural fullness. Eight of 24 patients had pure-tone thresholds greater than 25 dB hearing loss at two or more frequencies. Five of 24 of these patients experienced hearing loss outside of the 95% confidence interval for published age-matched control populations. There was sloping sensorineural hearing loss at 4 kHz and above in five of 24 patients. All eight patients with hearing loss experienced some degree of hearing loss at 4 kHz or above. Three patients had mild to moderate low-frequency sensorineural hearing loss. There were no tympanometric abnormalities suggestive of conductive involvement. Abnormal acoustic reflex decay was observed in one patient. We conclude that a significant number of patients with VKH experience sensorineural hearing loss and that every patient with VKH should undergo a review of systems for auditory abnormalities and referral for audiologic testing if symptomatic. It is possible that untreated patients may experience worse symptoms.

Vertigo in childhood: A clinical experience

Vertigo in childhood is a complaint consisting of a wide spectrum of diagnoses. The aim of this study was to evaluate pediatric patients with vertigo with normal eardrum and middle ear findings and discuss the differential diagnoses. Patient records of 50 children under 18 years of age with vertigo as the chief complaint, examined at the Baskent University, Research and Application Centers at Konya and Adana otorhinolaryngology clinics between May 2003 and October 2005 were retrospectively reviewed. The questionnaires, laboratory tests including blood samples, audiological and vestibular tests, and final diagnoses were analyzed. Patients with perforated eardrums, otitis media with effusion, and acute upper respiratory tract infections were not included in the study. The study group consisted of 50 patients (33 females, 66%; 17 males, 34%), between 4 and 17 years of age (mean age, 11.5+/-3.9 years). Severe sensorineural hearing loss was present in one patient unilaterally (2%) and one patient bilaterally (2%). Bilateral low-frequency sensorineural hearing loss was present in one patient (2%). Electronystagmography revealed central vestibular abnormalities in three patients (6%). Canal paresis was established in six patients (12%). The Dix-Hallpike test was positive in six patients (12%). The most frequent cause of vertigo was migraine, occurring in 34% of patients (n=17). Other less-frequent etiologies of vertigo were benign paroxysmal vertigo (n=6; 12%), benign paroxysmal positional vertigo (n=6; 12%), psychogenic vertigo (n=5; 10%), epilepsy (n=3; 6%), metabolic disorders (n=3; 6%), vestibular neuritis (n=2; 4%), Meniere's disease (n=1; 2%), perilymphatic fistula (n=1; 2%), amblyopia (n=1; 2%), and unclassifiable (n=5; 10%). Migraine was found to be the most frequent presenting diagnosis in childhood vertigo, although several peripheral vestibular disorders also were diagnosed. Evaluation of vertigo in childhood should begin with a thorough neuro-otologic evaluation and include other relevant multidisciplinary team members as needed to avoid unnecessary effort and cost.

腰椎麻酔後の両側低音障害型難聴例

Spinal anesthesia is a very common procedure that is performed on a daily basis in surgical clinical practice. Well known complications include headache, nausea and vertigo. Hearing loss is also a known yet uncommon complication that is usually transient and seldom presents any problems.We report a case of bilateral low-frequency sensorineural hearing loss following spinal anesthesia. A 57-year-old-man with a right indirect inguinal hernia underwent inguinal herinoplasty under spinal anesthesia. The following day he complained of post-spinal headache and bilateral tinnitus. On the second post operative day, he reported a feeling of impaired hearing in both ears and was referred to our clinic. We treated the patient with infusions consisting of low-molecular dextran and prednisolone from the day of admission. Four days after therapy hearing loss declined and eight days later the patient showed full auditory recovery in the low-frequency area. This low-frequency sensorineural hearing loss is thought to be caused by endolymphatic hydrops due to the loss of cerebrospinal fluid during the spinal anesthesia procedure. Suggested therapies are bed rest, infusions with low-molecular weight dextran, steroids, vitamin B12 and epidural blood patch.

Recurrent hearing loss after myelography treated with epidural blood patch

Transient hearing impairment is a known sequel after various procedures that result in loss of cerebrospinal fluid, such as lumbar puncture, spinal anesthesia and myelography. But persistent or recurrent hearing loss after dural puncture is a rare entity. We present a case with recurrent low-frequency sensorineural hearing loss after myelography. The patient was treated successfully by means of an epidural blood patch, although the conservative treatment was ineffective.

Mutation analysis of the WFS1 gene in seven Danish Wolfram syndrome families; four new mutations identified

Wolfram syndrome (WS) is a neuro-degenerative autosomal recessive (AR) disorder (OMIM #222300) caused by mutations in the WFS1 gene on 4p16.1. More than 120 mutations have been identified in WFS1 associated with AR WS, as well as autosomal dominant nonsyndromic low-frequency sensorineural hearing loss (LFSNHL). WFS1 variants were identified in eight subjects from seven families with WS, leading to the identification of four novel mutations, Q194X (nonsense), H313Y (missense), L313fsX360 (duplication frame shift) and F883fsX951 (deletion frame shift), and four previously reported mutations, A133T and L543R (missense), V415del (in frame triple deletion) and F883fsX950 (deletion frame shift). A mutation was found in 11/14 disease chromosomes, two subjects were homozygous for one mutation, one subject was compound heterozygous for two nucleotide substitutions (missense), one subject was compound heterozygous for a duplication and a deletion (frame shift), and in three families only one mutation was detected (Q194X and H313Y). All affected individuals shared clinically early-onset diabetes mellitus and progressive optic atrophy with onset in the first and second decades, respectively. In contrast, diabetes insipidus was present in two subjects only. Various degrees and types of hearing impairment were diagnosed in six individuals and cataract was observed in five subjects.

Intratympanic Dexamethasone and Hyaluronic Acid in Patients with Low-Frequency and Ménière's-Associated Sudden Sensorineural Hearing Loss

Steroids are widely used for the treatment of cochleovestibular disorders. Direct steroid application in the middle ear cavity, when combined with a round window membrane permeability-modulating substance, increases the level of the steroid reaching the target cells. We measured hearing in patients with idiopathic isolated low-frequency sensorineural hearing loss and in patients with sudden sensorineural hearing loss and a history of Ménière's disease. Contradictory reports about effectiveness of intratympanic steroid therapy on vertigo control and hearing improvement in patients with Ménière's disease exist in the literature. Eighteen patients with isolated low-frequency idiopathic sudden sensorineural hearing loss and 21 patients with sudden sensorineural hearing loss and a history of Ménière's disease were prospectively evaluated. The acute effect of the intratympanic application of dexamethasone with hyaluronic acid on hearing outcome after failure of an initial standard treatment with intravenous steroid and vasoactive substances was assessed. Evaluation was based on standard pure-tone audiometry findings. After intratympanic injection of dexamethasone and hyaluronic acid, 14 of the 18 patients with isolated low-frequency sensorineural hearing loss showed a significant improvement in hearing. After intratympanic therapy, 15 patients with a previous history of Ménière's disease and idiopathic isolated low-frequency sensorineural hearing loss showed an improvement in hearing on pure-tone audiometry, four remained unchanged, and two showed a tendency toward a slight deterioration. Intratympanic combined dexamethasone/hyaluronic acid application provides a reliable and safe therapeutic option for improvement of hearing in patients with isolated low-frequency idiopathic sudden sensorineural hearing loss or sensorineural hearing loss resulting from Ménière's disease who have failed intravenous steroid and vasoactive treatments.

A mutation in Wolfram syndrome type 1 gene in a Japanese family with autosomal dominant low-frequency sensorineural hearing loss

Conclusion. Our findings suggest that Wolfram syndrome type 1 gene (WFS1) mutation is an important cause of autosomal dominant low-frequency sensorineural hearing loss (LFSNHL) in Japan. Objective. DFNA6/14 is caused by a heterozygous mutation of WFS1 and is a common cause of autosomal dominant LFSNHL among populations in both Europe and the US. The purpose of this study was to investigate WFS1 mutations among Japanese patients whose phenotypes were consistent with those of DFNA6/14. Material and methods. Using audiometry and genetic analysis, we searched for WFS1 mutations in three unrelated Japanese patients with LFSNHL and a familial history of autosomal dominant hearing loss. Results. One patient carried a heterozygous G2700A mutation at codon 844 in exon 8, resulting in substitution of a threonine for an alanine (A844T). Genetic analysis of the available members of the patient's family showed that the A844T mutation segregated with LFSNHL, but was not detected in any of 140 control chromosomes. It thus appears likely that the A844T mutation is causative for hearing loss in this group. Speech audiometry, self-recording audiometry and auditory brainstem responses showed the patient to have cochlear deafness without retrocochlear dysfunction. No mutation was found in the other two patients.

Haplotype and linkage disequilibrium analysis of the CRMP1 and EVC genes

In this report, we present the haplotype and linkage disequilibrium (LD) pattern in the Collapsin Response Mediator Protein 1 (CRMP1) and Ellis-van Creveld syndrome (EVC) gene region. We genotyped eight different single nucleotide polymorphisms (SNPs) in the CRMP1 and EVC genes in 90 control individuals of diverse ethnicity. The minor allele frequencies ranged from 3.3-49.4%, with most having a frequency >25%. A total of 37 haplotypes were derived from these eight polymorphisms, with only one haplotype having a frequency >10%. Pairwise LD analysis showed a weak but significant LD between markers located about 243 kb apart in this region. The LD was significant between markers spaced about 208 kb apart in EVC, whereas no LD was found between a pair of markers located about 5 kb apart in CRMP1. However, in general, LD correlated with the distance between loci. The CRMP1 and EVC genes are located near WFS1, the Wolfram syndrome type 1 gene, in which mutations also cause low frequency sensorineural hearing loss (LFSNHL). The haplotypes obtained from these polymorphisms will be useful to track the segregation of phenotypes in families with Ellis-van Creveld syndrome, Weyers acrodental dysostosis, LFSNHL and Wolfram syndrome type 1.

Endoplasmic reticulum stress and N-glycosylation modulate expression of WFS1 protein

Mutations of the WFS1 gene are responsible for two hereditary diseases, Wolfram syndrome and low frequency sensorineural hearing loss. The WFS1 protein is a glycoprotein located in the endoplasmic reticulum (ER) membrane but its function is poorly understood. Herein we show WFS1 mRNA and protein levels in pancreatic islets to be increased with ER-stress inducers, thapsigargin and dithiothreitol. Another ER-stress inducer, the N-glycosylation inhibitor tunicamycin, also raised WFS1 mRNA but not protein levels. Site-directed mutagenesis showed both Asn-663 and Asn-748 to be N-glycosylated in mouse WFS1 protein. The glycosylation-defective WFS1 protein, in which Asn-663 and Asn-748 had been substituted with aspartate, exhibited an increased protein turnover rate. Consistent with this, the WFS1 protein was more rapidly degraded in the presence of tunicamycin. These data indicate that ER-stress and N-glycosylation play important roles in WFS1 expression and stability, and also suggest regulatory roles for this protein in ER-stress induced cell death.

Familial auditory neuropathy.

Auditory neuropathy is a sensorineural hearing disorder characterized by absent or abnormal auditory brainstem responses and normal cochlear outer hair cell function as measured by otoacoustic emission recordings. Many risk factors are thought to be involved in its etiology and pathophysiology. Four Chinese pedigrees with familial auditory neuropathy were presented to demonstrate involvement of genetic factors in the etiology of auditory neuropathy. Probands of the above-mentioned pedigrees, who had been diagnosed with auditory neuropathy, were evaluated and followed in the Department of Otolaryngology-Head and Neck Surgery, China People Liberation Army General Hospital (Beijing, China). Their family members were studied, and the pedigree maps established. History of illness, physical examination, pure-tone audiometry, acoustic reflex, auditory brainstem responses, and transient evoked and distortion-product otoacoustic emissions were obtained from members of these families. Some subjects received vestibular caloric testing, computed tomography scan of the temporal bone, and electrocardiography to exclude other possible neuropathic disorders. In most affected patients, hearing loss of various degrees and speech discrimination difficulties started at 10 to 16 years of age. Their audiological evaluation showed absence of acoustic reflex and auditory brainstem responses. As expected in auditory neuropathy, these patients exhibited near-normal cochlear outer hair cell function as shown in distortion product otoacoustic emission recordings. Pure-tone audiometry revealed hearing loss ranging from mild to profound in these patients. Different inheritance patterns were observed in the four families. In Pedigree I, 7 male patients were identified among 43 family members, exhibiting an X-linked recessive pattern. Affected brothers were found in Pedigrees II and III, whereas in pedigree IV, two sisters were affected. All the patients were otherwise normal without evidence of peripheral neuropathy at the time of writing. Patients with characteristics of nonsyndromic hereditary auditory neuropathy were identified in one large and three smaller Chinese families. Pedigree analysis suggested an X-linked, recessive hereditary pattern in one pedigree and autosomal recessive inheritances in the other three pedigrees. The phenotypes in the study were typical of auditory neuropathy; they were transmitted in different inheritance patterns, indicating clinical and genetic heterogeneity of this disorder. The observed inheritance and clinical audiological findings are different from those previously described for nonsyndromic low-frequency sensorineural hearing loss. This information should facilitate future molecular linkage analyses and positional cloning for the relative genes contributing to auditory neuropathy.

Patient selection for incus body coupling of a totally implantable middle ear implant

Objective—To evaluate audiologic selection criteria for incus body coupling (IBC) of a totally implantable middle ear implant (TI-MEI) for the treatment of sensorineural hearing loss (SNHL).Material and Methods—The protocol is specified in the Investigational Device Exemption of a Food and Drug Administration-approved multicenter clinical trial. The prospective study compared pre- and postoperative hearing levels using each patient as their own control. In addition, an implant on/off comparison was made. All patients had a follow-up interval of at least 6 months. Audiologic assessment tests included speech discrimination in quiet as the primary efficacy variable and pure-tone audiometry (aided thresholds), gain, speech recognition in noise and subject satisfaction using standardized questionnaires and visual analog scales (VASs) as secondary efficacy variables. The study group of patients (n = 13) was divided into 3 subgroups based on their pure-tone and speech discrimination scores: Group A consisted of 6 patients, Group B 9 patients and Group C of all 13 patients. All patients suffered from long-standing bilateral moderate to severe SNHL. Five patients were dissatisfied hearing aid (HA) users and eight subjects could not wear HAs. All patients were implanted with a TI-MEI which was coupled to the incus body. The amplification level of the device was set postoperatively using inductive digital fitting based on "most comfortable loudness" specifications.Results—The implant produced median improvements from 30% (optimally fit bilateral HAs; n = 5) and 50% (HA non-users; n = 8) to 70% word recognition at 60 dB SPL. Average word recognition scores at 60, 80 and 90 dB SPL in Groups A and B showed increases from 42% (interquartile range +27%, -12%) to 93.5% (+3%, -5%) and 92.5% (+3%, -7%), respectively. In the presence of background noise, the sentence recognition threshold ranged from -2 to 1 dB signal-to-noise ratio. Maximum amplification was 50 dB at 3 kHz and 55 dB at 4 kHz. In Groups A and B, VASs revealed improvements in both natural sound impression and clarity from 62-70% of a natural sound impression to maximum scores of 100%. Using the standardized Gothenburg profile, subjective evaluations of hearing, orientation, social behavior and self-confidence reached 96-98%, 92-96% and 84-92% of the maximum score for Groups A-C, respectively.Conclusions—In selected cases, IBC of the TI-MEI investigated herein may be indicated for the treatment of SNHL, provided the following four conditions are met. First, the patient does not derive sufficient benefit from conventional HAs. Second, the specific indication for IBC is restricted to situations that do not allow the coupling of the MEI to the long incus process (e.g. due to an anatomical variation of facial nerve location). Third, IBC is restricted to patients with a steeply sloped moderate to severe high frequency SNHL, amounting to 90 dB HL from 3 to 8 kHz. Patients with low frequency SNHL should not be operated on with the IBC technique, as maximum low frequency hearing loss at 0.5 kHz must not exceed 30 dB. Fourth, Schueller's X-ray should reveal normal mastoid pneumatization. Being restricted to a 6-month follow-up period, this paper provides early clinical results and no clinical evidence of long-term efficiency of the implant.

Mutations in the Wolfram syndrome type 1 gene (WFS1) define a clinical entity of dominant low-frequency sensorineural hearing loss.

To describe low-frequency sensorineural hearing loss (LFSNHL) inherited as a dominant trait in 3 families and in 1 sporadic case. Longitudinal clinical study from 1968 to 2001. Tertiary care hospital; field studies conducted by molecular genetic research laboratory. Dominant LFSNHL families. Questionnaires, serial audiograms, and interviews, correlated with molecular genetic data. Symptoms, age of onset, serial audiometric data, and hearing aid use. Low-frequency sensorineural hearing loss is typically diagnosed in the first decade and slowly progresses over decades; LFSNHL is often asymptomatic in young patients, few of whom use hearing aids. Speech perception becomes affected in later decades when patients develop high-frequency loss. Even children with a strong family history of dominant LFSNHL were not monitored routinely. Penetrance appears complete in that all individuals with a genetic mutation developed hearing loss. Dominant LFSNHL is most commonly caused by mutations in the Wolfram syndrome type 1 gene (WFS1). Mutations in WFS1 also cause a rare recessive syndromic form of hearing loss known as Wolfram syndrome or DIDMOAD (diabetes insipidus, diabetes mellitus, optic atrophy, and deafness). Routine newborn hearing screening methods will not typically identify hearing loss affecting frequencies below 2000 Hz; thus, children at risk must be specifically monitored. Genetic counseling and genetic testing may be useful in the management of patients with this type of hearing loss.

Progression of low-frequency sensorineural hearing loss (DFNA6/14-WFS1).

To assess the audiometric profile and speech recognition characteristics in affected members of 2 families with DFNA6/14 harboring heterozygous mutations in the WFS1 gene that cause an autosomal dominant nonsyndromic sensorineural hearing impairment trait. Family study. Tertiary referral center. Patients Thirteen patients from 2 recently identified Dutch families with DFNA6/14 (Dutch III and IV). Cross-sectional and longitudinal analyses of pure-tone thresholds at octave frequencies of 0.25 to 8 kHz were performed, and speech phoneme recognition scores were assessed. Progression was evaluated by linear regression analysis with and without correction for presbycusis. All individuals showed low-frequency hearing impairment. The 2-kHz frequency was more affected in the Dutch III family than in the Dutch IV family. Progressive hearing loss beyond presbycusis was found in the Dutch IV family and in 3 individuals in the Dutch III family. Annual threshold deterioration was between 0.6 and 1 dB per year at all frequencies. The speech recognition scores in the Dutch III family showed significantly more deterioration at increasing levels of hearing impairment compared with those in the Dutch IV family. Both families showed an autosomal dominant, progressive, low-frequency sensorineural hearing impairment caused by heterozygous WFS1 mutations.

The WFS1 gene, responsible for low frequency sensorineural hearing loss and Wolfram syndrome, is expressed in a variety of inner ear cells.

Heterozygous mutations in the WFS1 gene are responsible for autosomal dominant low frequency hearing loss at the DFNA6/14 locus, while homozygous or compound heterozygous mutations underlie Wolfram syndrome. In this study we examine expression of wolframin, the WFS1-gene product, in mouse inner ear at different developmental stages using immunohistochemistry and in situ hybridization. Both techniques showed compatible results and indicated a clear expression in different cell types of the inner ear. Although there were observable developmental differences, no differences in staining pattern or gradients of expression were observed between the basal and apical parts of the cochlea. Double immunostaining with an endoplasmic reticulum marker confirmed that wolframin localizes to this organelle. A remarkable similarity was observed between cells expressing wolframin and the presence of canalicular reticulum, a specialized form of endoplasmic reticulum. The canalicular reticulum is believed to be involved in the transcellular movements of ions, an important process in the physiology of the inner ear. Although there is nothing currently known about the function of wolframin, our results suggest that it may play a role in inner ear ion homeostasis as maintained by the canalicular reticulum.

A PCR-RFLP assay for the A716T mutation in the WFS1 gene, a common cause of low-frequency sensorineural hearing loss.

Nonsyndromic low-frequency sensorineural hearing loss (LFSNHL) is an unusual type of hearing loss that affects frequencies at 2,000 Hz and below. Recently, we reported five different heterozygous missense mutations in the Wolfram syndrome gene, WFS1, found to be responsible for LFSNHL in six families. One of the five mutations, A716T, may be a common cause of LFSNHL, as it has been reported in three families to date (Bespalova et al., 2001; Young et al., 2001). We have developed a PCR-based restriction fragment-length polymorphism (RFLP) assay to detect the A716T mutation in a simple, specific test. This method was evaluated with DNA samples from a family in which the A716T mutation was segregating with LFSNHL. This simple assay successfully detected the presence of the A716T mutation in all of the individuals predicted to be affected, based on audiologic results. Therefore, this assay can be routinely used for initial screening of the A716T mutation in patients with LFSNHL, before screening the entire coding region of the WFS1 gene.

Mutations in the WFS1 gene that cause low-frequency sensorineural hearing loss are small non-inactivating mutations.

Hereditary hearing impairment is an extremely heterogeneous trait, with more than 70 identified loci. Only two of these loci are associated with an auditory phenotype that predominantly affects the low frequencies (DFNA1 and DFNA6/14). In this study, we have completed mutation screening of the WFS1 gene in eight autosomal dominant families and twelve sporadic cases in which affected persons have low-frequency sensorineural hearing impairment (LFSNHI). Mutations in this gene are known to be responsible for Wolfram syndrome or DIDMOAD (diabetes insipidus, diabetes mellitus, optic atrophy, and deafness), which is an autosomal recessive trait. We have identified seven missense mutations and a single amino acid deletion affecting conserved amino acids in six families and one sporadic case, indicating that mutations in WFS1 are a major cause of inherited but not sporadic low-frequency hearing impairment. Among the ten WFS1 mutations reported in LFSNHI, none is expected to lead to premature protein truncation, and nine cluster in the C-terminal protein domain. In contrast, 64% of the Wolfram syndrome mutations are inactivating. Our results indicate that only non-inactivating mutations in WFS1 are responsible for non-syndromic low-frequency hearing impairment.

Mutations in the Wolfram syndrome 1 gene (WFS1) are a common cause of low frequency sensorineural hearing loss.

Non-syndromic low frequency sensorineural hearing loss (LFSNHL) affecting only 2000 Hz and below is an unusual type of hearing loss that worsens over time without progressing to profound deafness. This type of LFSNHL may be associated with mild tinnitus but is not associated with vertigo. We have previously reported two families with autosomal dominant LFSNHL linked to adjacent but non-overlapping loci on 4p16, DFNA6 and DFNA14. However, further study revealed that an individual with LFSNHL in the DFNA6 family who had a recombination event that excluded the DFNA14 candidate region was actually a phenocopy, and consequently, DFNA6 and DFNA14 are allelic. LFSNHL appears to be genetically nearly homogeneous, as only one LFSNHL family is known to map to a different chromosome (DFNA1). The DFNA6/14 critical region includes WFS1, the gene responsible for Wolfram syndrome, an autosomal recessive disorder characterized by diabetes mellitus and optic atrophy, and often, deafness. Herein we report five different heterozygous missense mutations (T699M, A716T, V779M, L829P, G831D) in the WFS1 gene found in six LFSNHL families. Mutations in WFS1 were identified in all LFSNHL families tested, with A716T arising independently in two families. None of the mutations was found in at least 220 control chromosomes with the exception of V779M, which was identified in 1/336 controls. This frequency is consistent with the prevalence of heterozygous carriers for Wolfram syndrome estimated at 0.3-1%. An increased risk of sensorineural hearing loss has been reported in such carriers. Therefore, we conclude that mutations in WFS1 are a common cause of LFSNHL.

Audio-vestibular evaluation in patients with Behçet's syndrome.

A prospective controlled clinical study was carried out at the Department of Ophthalmology and ENT, Inönü University Medical Faculty, Turgut Ozal Medical Center, Research Hospital, to evaluate the audio-vestibular involvement in patients with Behçet's syndrome compared with controls. Twenty-five consecutive patients with Behçet's syndrome (mean age +/- SD, 34.96 +/- 8.50) and 20 age- and sex-matched healthy volunteers (hospital staff) as control subjects (mean age +/- SD, 34.45 +/- 9.16) were included in this study. Behçet's patients were divided into two groups according to the number of criteria, complete (all four major criteria) and incomplete (three major criteria without ocular involvement). The groups were compared with each other or controls regarding inner ear involvement. Audiometric pure-tone thresholds at 125 to 8000 Hz were obtained in all subjects in both groups, and pure tone average (PTA) hearing thresholds were calculated for the middle, high and low frequencies. In addition, short increment sensitivity index (SISI), tone decay and BERA examinations were performed in all Behçet's patients. Sensorineural hearing loss (SNHL) was present in six of 25 patients with Behçet's syndrome. Two Behçet's patients had unilateral total SNHL, two had bilateral moderate level SNHL, one had bilateral low-frequency SNHL and one bilateral high frequency SNHL. In two, BERA, and in five SISI, examination disclosed inner ear involvement. In control subjects, the past medical history was normal and there was no consistent audio-vestibular complaint. Their PTA thresholds were all in the normal range. Otoscopic examination findings were normal, with intact, mobile tympanic membranes in both groups. The present study showed that audio-vestibular involvement is not infrequent in Behçet's syndrome compared with age- and sex-matched healthy controls, and it is under-estimated. All Behçet's patients should regularly be followed by an otolaryngologists and be given information about the possibility of inner ear involvement. According to our results, hearing loss occurs more often in older patients and also in the complete form of Behçet's syndrome.

Regarding the mechanism of sudden low frequency sensorineural hearing loss

Regarding the mechanism of sudden low frequency sensorineural hearing loss