Hearing loss and its association with the proteome of perilymph, cerebrospinal fluid, and tumor tissue in patients with vestibular schwannoma.

This study examined the association between hearing loss in sporadic vestibular schwannoma patients and the proteome of perilymph (PL), cerebrospinal fluid (CSF), and vestibular schwannoma. Intraoperative sampling of PL and of CSF, and biopsy of vestibular schwannoma tissue, was performed in 32, 32, and 20 patients with vestibular schwannoma, respectively. Perilymph and CSF in three patients with meningioma and normal hearing were also sampled. The proteomes were identified by liquid chromatography coupled to high-resolution tandem mass spectrometry. Preoperative hearing function of the patients was evaluated with pure tone audiometry, with mean values at frequencies of 500, 1000, 2000, and 4000 Hz (PTA4) in the tumor-affected ear used to delineate three hearing groups. Analysis of the PL samples revealed significant upregulation of complement factor H-related protein 2 (CFHR2) in patients with severe to profound hearing loss after false discovery rate correction. Pathway analysis of biofunctions revealed higher activation scores in the severe/profound hearing loss group of leukocyte migration, viral infection, and migration of cells in PL. Upregulation of CFHR2 and activation of these pathways indicate chronic inflammation in the cochlea of vestibular schwannoma patients with severe to profound hearing loss compared with patients with normal hearing or mild hearing loss.

Metformin mediates neuroprotection and attenuates hearing loss in experimental pneumococcal meningitis.

BACKGROUND: Pneumococcal meningitis is associated with high risk of neurological sequelae such as cognitive impairment and hearing loss. These sequelae are due to parenchymal brain and inner ear damage primarily induced by the excessive inflammatory reaction in response to bacterial brain invasion. Metformin-a biguanide drug to treat diabetes mellitus type 2-was recently found to suppress neuroinflammation and induce neuroregeneration. This study evaluated the effect of metformin adjunctive to antibiotics on neuroinflammation, brain and inner ear damage, and neurofunctional outcome in experimental pediatric pneumococcal meningitis. METHODS: Eleven-day-old Wistar rats were infected intracisternally with 5.22 ± 1.27 × 103 CFU Streptococcus pneumoniae and randomized for treatment with metformin (50 mg/kg, i.p., once daily for 3 weeks) plus ceftriaxone (100 mg/kg, i.p., bid, n = 61) or ceftriaxone monotherapy (n = 79). Cortical damage and hippocampal apoptosis were evaluated histomorphometrically 42 h post infection. Cerebrospinal fluid cytokine levels were analyzed during acute infection. Five weeks post infection, auditory brainstem responses were measured to determine hearing thresholds. Spiral ganglion neuron density and abundance of recently proliferated and integrated hippocampal granule neurons were assessed histologically. Additionally, the anti-inflammatory effect of metformin was studied in primary rat astroglial cells in vitro. RESULTS: Upon pneumococcal infection, metformin treatment significantly reduced levels of inflammatory cytokines and nitric oxide production in cerebrospinal fluid and in astroglial cell cultures in vitro (p < 0.05). Compared to animals receiving ceftriaxone monotherapy, adjunctive metformin significantly reduced cortical necrosis (p < 0.02) during acute infection and improved median click-induced hearing thresholds (60 dB vs. 100 dB, p < 0.002) 5 weeks after infection. Adjuvant metformin significantly improved pure tone hearing thresholds at all assessed frequencies compared to ceftriaxone monotherapy (p < 0.05) and protected from PM-induced spiral ganglion neuron loss in the inner ear (p < 0.05). CONCLUSION: Adjuvant metformin reduces brain injury during pneumococcal meningitis by decreasing the excessive neuroinflammatory response. Furthermore, it protects spiral ganglion neurons in the inner ear and improves hearing impairments after experimental pneumococcal meningitis. These results identify adjuvant metformin as a promising therapeutic option to improve the outcome after pediatric pneumococcal meningitis.

Cerebrospinal fluid leak during stapes surgery: Gushing leaks and oozing leaks, two different phenomena.

Cerebrospinal fluid (CSF) leak is an uncommon event that can occur during stapes surgery. Such leaks can be classified as gushing leaks (stapes gushers) and oozing leaks. A stapes gusher is a massive flow of CSF through the perforated footplate that fills the middle ear suddenly, while an oozing leak is a slower and less profuse flow. We conducted a retrospective, observational, multicenter study of 38 patients-23 men and 15 women, aged 23 to 71 years (mean: 47)-who had experienced a CSF leak during stapes surgery. Patients were divided into various groups according to the type of surgical procedure performed and the type of postoperative complications they experienced. Audiometric and clinical evaluations were carried out pre- and postoperatively. Correlations among surgical variations (total or partial stapedectomy, placement of a prosthesis), hearing outcomes, and the incidence of postoperative complications (postoperative CSF leak and vertigo) were studied. Our statistical analysis revealed that gushing leaks and oozing leaks result in different degrees of hearing impairment and different rates of complications. We recommend that an individual approach be used to manage these complications.

Abordaje por fosa media para el cierre de fístulas de líquido cefalorraquídeo espontáneas a oído medio / Middle cranial fossa approach for the repair of spontaneous cerebrospinal fluid leaks to the middle ear

Introducción. Las fístulas espontáneas de líquido cefalorraquídeo (LCR) al oído medio por dehiscencias espontáneas óseas del tegmen pueden ser origen de hipoacusia de transmisión y complicarse con meningitis u otras complicaciones intracraneales. El tratamiento quirúrgico para el cierre de estas comunicaciones anómalas puede realizarse por vía transmastoidea o por abordaje por fosa craneal media (FCM). Material y métodos. Se realiza un estudio retrospectivo de los pacientes intervenidos en nuestro servicio de fístulas de LCR espontáneas a oído medio por medio de abordaje por FCM en un período de 6años (2009-2014). Resultados. Se intervienen 13 pacientes con fístulas espontáneas por este abordaje, siendo el síntoma de presentación de todos ellos la hipoacusia de transmisión. En todos los casos se realiza un cierre multicapa (músculo, fascia temporal y cortical ósea) para cerrar el defecto o defectos existentes. El seguimiento mínimo en todos ellos es de 14meses, con cierre de la fístula en todos los casos salvo en uno, que precisó reintervención. No hubo complicaciones intraoperatorias ni postoperatorias debido a la técnica empleada, y la audiometría se normaliza en todos los casos, salvo en el caso de fracaso mencionado. Conclusiones. El abordaje por FCM y cierre en multicapa es una técnica adecuada y eficaz para el cierre de fístulas de LCR espontáneas a oído medio y consigue, además del cierre de la comunicación, el re-establecimiento de la audición (AU)

Introduction. Spontaneous cerebrospinal fluid (CSF) leaks to the middle ear due to tegmen tympani defects can result in hearing loss or hypoacusis and predispose to meningitis as well as other neurological complications. Surgical repair of the defect can be performed through a middle cranial fossa (MCF) approach or a transmastoid approach. Material and methods. We conducted a retrospective study of the patients in our Department due to a spontaneous CSF leak to the middle ear treated using a MCF approach during a 6-year period (2009-2014). Results. Thirteen patients with spontaneous CSF leak to the middle ear were treated with this approach. The primary and first symptom in all of them was conductive hearing loss. In all cases, the defect or defects were closed in a multilayer manner using muscle, temporalis fascia and cortical bone. Minimum follow-up in this series was 14 months, with successful closure in all but one patient (who required reintervention). We found no intra- or postoperative complications due to the craniotomy, and the audiometry improved and normalised in all cases except for the failed case. Conclusions. The MCF approach with a multilayer closure of the defect is an effective technique for repairing spontaneous CSF leaks to the middle ear and for restoring hearing in these patients (AU)

Effect of Spinal Anaesthesia on Hearing Threshold

Background: Hearing loss following spinal anaesthesia is a known yet uncommonly reported complication. This study was aimed at determining the incidence and type of hearing loss (HL) following spinal anaesthesia (SA) and the relationship with the size of spinal needle. Methods: A prospective study of patients scheduled for spinal anaesthesia for surgery at the Operating room and Otorhinolaryngology department in a tertiary centre was undertaken. The audiometry was done and the pre- and post - anaesthesia results were compared.Results: Ninety - four ears of 47 patients; 16 males and 31 females; age range between 21 and 63 years (mean + SD= 41+5) were included. The duration of anaesthesia was between 90 and 150 minutes (mean + SD= 116+9). HL was seen in 9 ears of 7 patients (15) and tinnitus in 14 ears. The preoperative and postoperative BC PTA were 10 - 45dB (mean + SD= 26+ 5) and 25 - 65dB (mean + SD=38+5) respectively; (P= 0.02) while the preoperative and postoperative AC PTA in the early frequency range (0-100Hz) were between 5 - 45dB (mean + SD= 20+ 5) and 25 - 50dB (mean + SD=25+7) respectively; (P= 0.08). There was significant difference in the mean BC PTA between those who had procedure less than 1 hour; 37.2dB and those greater than 1 hour 38.4dB; (P=0.004). According to the Quincke needle sizes; the mean BC PTA among those who had 26G and 27G were 37.4dB and 38.1dB respectively (P=0.2). Conclusion: HL complicating SA is significant and associated with duration of procedure thus should be included in informed consent for medico-legal and ethical reasons and measures must be taken to avoid the leak of cerebrospinal fluid