Tinnitus Perception in Light of a Parietal Operculo-Insular Involvement: A Review.

In tinnitus literature, researchers have increasingly been advocating for a clearer distinction between tinnitus perception and tinnitus-related distress. In non-bothersome tinnitus, the perception itself can be more specifically investigated: this has provided a body of evidence, based on resting-state and activation fMRI protocols, highlighting the involvement of regions outside the conventional auditory areas, such as the right parietal operculum. Here, we aim to conduct a review of available investigations of the human parietal operculo-insular subregions conducted at the microscopic, mesoscopic, and macroscopic scales arguing in favor of an auditory-somatosensory cross-talk.

Tracking white-matter brain modifications in chronic non-bothersome acoustic trauma tinnitus.

Subjective tinnitus is a symptom characterized by the perception of sound with no external acoustic source, most often accompanied by co-morbidities. To date, the specific role of white matter abnormalities related to tinnitus reaches no consensus in the literature. The goal of this study was to explore the structural connectivity related to tinnitus percept per se, thus focusing on a specific population presenting chronic non-bothersome tinnitus of similar etiology (noise induced) without co-morbidities.

Functional Connectivity in Chronic Nonbothersome Tinnitus Following Acoustic Trauma: A Seed-Based Resting-State Functional Magnetic Resonance Imaging Study.

Tinnitus and its mechanisms are an ongoing subject of interrogation in the neuroscientific community. Although most current models agree that it encompasses multiple structures within and outside the auditory system, evidence provided in the literature suffers from a lack of convergence. To further our understanding of contributions to tinnitus lying outside the auditory system, we explored a new model based on a proprioceptive hypothesis specifically in subjects experiencing chronic nonbothersome tinnitus due to acoustic trauma.

Relationship Between Audio-Vestibular Functional Tests and Inner Ear MRI in Meniere's Disease.

Objectives: Meniere's disease is an inner ear disorder generally attributed to an endolymphatic hydrops. Different electrophysiological tests and imaging techniques have been developed to improve endolymphatic hydrops diagnosis. The goal of our study was to compare the sensitivity and the specificity of delayed inner ear magnetic resonance imaging (MRI) after intravenous injection of gadolinium with extratympanic clicks electrocochleography (EcochG), phase shift of distortion product otoacoustic emissions (shift-DPOAEs), and cervical vestibular-evoked myogenic potentials (cVEMP) for the diagnosis of Meniere's disease.

Tinnitus and Associated Handicaps in the French Mountain Artillery: Assessment by the Tinnitus Handicap Inventory.

Introduction: Tinnitus and associated handicap related to acoustic trauma sequelae have never been assessed in the French artillery. Although impulsive noise exposure to firearms and canons are thought to increase prevalence of tinnitus among soldiers, recent studies demonstrating this fact are missing.

Materials And Methods: Here, a representative sample of 389 soldiers from an operational mountain artillery regiment was surveyed.

Specific activation of operculum 3 (OP3) brain region during provoked tinnitus-related phantom auditory perceptions in humans.

The phantom sound perception mechanism by which a sound perception occurs without any external sound source is still enigmatic. According to our previous fMRI study, a small region in the parietal operculum 3 was hyperactivated as a function of tinnitus periodicity in subjects with acoustic trauma tinnitus sequelae. This region was localized in the vicinity of neural correlates of middle-ear tympano-ossicular chain movements due to pressure variations.

Abnormal cortical sensorimotor activity during "Target" sound detection in subjects with acute acoustic trauma sequelae: an fMRI study.

The most common consequences of acute acoustic trauma (AAT) are hearing loss at frequencies above 3 kHz and tinnitus. In this study, we have used functional Magnetic Resonance Imaging (fMRI) to visualize neuronal activation patterns in military adults with AAT and various tinnitus sequelae during an auditory "oddball" attention task. AAT subjects displayed overactivities principally during reflex of target sound detection, in sensorimotor areas and in emotion-related areas such as the insula, anterior cingulate and prefrontal cortex, in premotor area, in cross-modal sensory associative areas, and, interestingly, in a region of the Rolandic operculum that has recently been shown to be involved in tympanic movements due to air pressure.

Cortical representation of tympanic membrane movements due to pressure variation: an fMRI study.

Middle ear sensory information has never been localized in the homunculus of the somatosensory cortex (S1). We investigated the somatosensory representation of the middle ear in 15 normal hearing subjects. We applied small air pressure variations to the tympanic membrane while performing a 3T-fMRI study.

Prediction of soman-induced cerebral damage by distortion product otoacoustic emissions.

The organophosphorus nerve agent soman is an irreversible cholinesterase (ChE) inhibitor that can produce long-lasting seizures and seizure-related brain damage (SRBD) in which acetylcholine and glutamate are involved. Since these neurotransmitters play a key-role in the auditory function, it was hypothesized that a hearing test may be an efficient way for detecting the central effects of soman intoxication. In the present study, distortion product otoacoustic emissions (DPOAEs), a non-invasive audiometric method, were used in rats administered with soman (70 μg/kg).

Hearing status after an industrial explosion: experience of the AZF explosion, 21 September 2001, France.

Objectives: Following the explosion of a chemical plant in France, a study was conducted to analyse the relationship between hearing thresholds and distance from the explosion based on post- and pre-blast audiometric data, and to describe the functional symptoms and visits for hearing problems.

Methods: Audiometric tests with standard procedure of 511 workers of a company located near the explosion were proposed and conducted by the occupational medicine department after the explosion. Past occupational noise exposure, past medical history of ear problems, distance from the explosion, functional symptoms and visits for hearing problems following explosion and results of past audiometric tests if available were collected.

Distortion product otoacoustic emissions as non-invasive biomarkers and predictors of soman-induced central neurotoxicity: a preliminary study.

The organophosphorus nerve agent soman is an irreversible cholinesterase (ChE) inhibitor that can produce long-lasting seizures and brain damage in which the neurotransmitters acetylcholine and glutamate are involved. These same neurotransmitters play key-roles in the auditory function. It was then assumed that exploring the hearing function may provide markers of the central events triggered by soman intoxication.

Susceptibility to tinnitus revealed at 2 kHz range by bilateral lower DPOAEs in normal hearing subjects with noise exposure.

We investigated potential markers of susceptibility to tinnitus in a group of normal hearing young pilots aged 25-35 years and with 8 +/- 5 years of aircraft noise exposure. 316 pilots were interviewed about their tinnitus status and were tested for hearing thresholds (audiograms) and distortion products otoacoustic emissions (DPOAE-grams). There was no subject with permanent tinnitus.

Otoacoustic emissions and persistent tinnitus after acute acoustic trauma.

Objectives: To follow up the auditory status of military personnel after an acute acoustic trauma and to identify the possible predictive value of hearing thresholds and otoacoustic emissions during the first 24 hours after the acoustic trauma.

Study Design: A group of 24 young military subjects, aged 22 +/- 2.3 years, without any otologic problem before the acoustic trauma, were examined at three time intervals after an accidental acoustic trauma caused by the discharge of a firearm: 24 hours, 72 hours, and 15 days.

Hearing in military pilots: one-time audiometry in pilots of fighters, transports, and helicopters.

Introduction: Pilots are exposed to potentially harmful levels of noise, the actual consequences of which are still poorly documented. We have determined the audiometric profiles of pilots as a function of age and type of aircraft (i.e.

Moderate variations of mood/emotional states related to alterations in cochlear otoacoustic emissions and tinnitus onset in young normal hearing subjects exposed to gun impulse noise.

This study was designed to test whether under impulse noise exposure mood and emotional states could play a role in the onset of tinnitus and/or could modify cochlear sensitivity objectively measured with distortion product otoacoustic emissions (DPOAEs). The experimental design consisted in a short follow-up study of 54 young military subjects (20+/-2 years old), psychologically normal, with normal hearing, during two consecutive days of target practice rounds. Data collection included an abbreviated version of the profile of mood states (POMSs) inventory [Profile of Mood States, Educational and Industrial Testing Service, San Diego, 1971], questionnaires on tinnitus perception (previous history and after shooting) and DPOAEs measurements before and after shooting.

Over-stimulation of the vestibular system and body balance.

The purpose of this study was to examine whether an over-stimulation of the vestibular system, induced by thousands of time saccadic head stimulations, affects the vestibular sensitivity, and consequently if such a phenomenon could contribute to the deterioration of postural stability observed after a long distance running exercise. Eighteen athletic subjects performed a 20.5 km over ground race with an average speed of 15 km x h(-1), corresponding roughly to 7,500 strides shocks with associated saccadic accelerations transmitted to the head.

DPOAEs in young normal-hearing subjects with histories of otitis media: evidence of sub-clinical impairments.

To investigate the origin of the susceptibility to noise in subjects with histories of otitis media (OM), we assessed early sub-clinical impairments in normally hearing subjects with a history of OM using distortion product otoacoustic emissions (DPOAEs). DPOAEs of 213 normal-hearing subjects aged 18-24 years were obtained and comparisons of DPOAE levels in several groups as a function of OM past infections were tested by ANOVA. A main finding was that young normal-hearing subjects with a history of OM had significantly lower DPOAEs over all octaves tested compared to normal-hearing subjects without antecedent of OM.

Ex vivo expansion marginally amplifies repopulating cells from baboon peripheral blood mobilized CD34+ cells.

The ability of ex vivo expansion to increase the long-term repopulating capacity of a graft is still unknown. One problem is the most reliable way to quantify transplantable cells. We addressed this point in a baboon model based on autologous transplantation of serial limiting doses of non-manipulated or ex vivo-expanded mobilized CD34+ cells and determined the threshold doses of non-manipulated and expanded cells which supported long-term multilineage engraftment.