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Otology
Published in Adnan Darr, Karan Jolly, Jameel Muzaffar, ENT Vivas, 2023
Jameel Muzaffar, Chloe Swords, Adnan Darr, Karan Jolly, Manohar Bance, Sanjiv Bhimrao
Acoustic reflex: Stapedius muscle in middle ear contracts in response to an intense sound Crossed vs uncrossedCN VIII > cochlear nucleus > SOC (bilateral) > FN nucleus (bilateral) > stapediusPattern of abnormality helps identify site of lesionNormal stapedial reflex threshold is 70–100 dB above the pure tone thresholdIf suspect retrocochlear pathology, test acoustic reflex decay: Decreased auditory perception with sustained stimulus
Conductive mechanism
Published in Stanley A. Gelfand, Hearing, 2017
Several studies have demonstrated that the acoustic reflex is absent when there is pathology affecting the stapedius muscle (Jepsen, 1955; Klockhoff, 1961; Feldman, 1967); however, the acoustic reflex was still obtained in two cases of tensor tympani pathology (Jepsen, 1955). It might be added at this point that a measurable tensor tympani reflex is known to occur as part of a startle reaction to very intense sound (Djupesland, 1964), or in response to a jet of air directed into the eye (Klockhoff, 1961). Based on these observations, one is drawn to conclude that in humans the acoustic reflex is a stapedius reflex.
Auditory Neuropathy Spectrum Disorder and Retrocochlear Disorders in Adults and Children
Published in John C Watkinson, Raymond W Clarke, Christopher P Aldren, Doris-Eva Bamiou, Raymond W Clarke, Richard M Irving, Haytham Kubba, Shakeel R Saeed, Paediatrics, The Ear, Skull Base, 2018
Further study has permitted the characterization of this group of disorders, and better assessment of these patients. These cases are now recognized as relatively common (5–12% of those previously considered to have severe to profound hearing loss in paediatric populations,11,12 with an estimated 1 in 7000 of neonates, assessed by universal newborn hearing screening,13 showed abnormal VIIIth nerve function) and probably represent a heterogeneous group where the common feature is disordered temporal processing (i.e. synchronization of sound). Progressive AN is reported in association with age-related degenerative changes, toxic effects of noise, mitochondrial, genetic and autoimmune disorders, etc.14 The first large series15 identified 49 cases from 543 patients who had either no ABR response or absent waves III and V. In seven patients, the audiometric data ranged from normal hearing to moderate impairment, i.e. 14% had better hearing sensitivity than might have been expected from their ABR, which was completely absent in these cases. Each of these seven patients also had abnormal acoustic reflex findings. Although the range of deficits as identified on medical, behavioural and electrophysiological testing was variable, there were many common features, including perinatal insults such as perinatal asphyxia, hyperbilirubinaemia or head injury. Tests of psycholinguistic abilities revealed significantly worse performance in auditory as compared to visual tasks, and speech discrimination testing revealed worse scores than would have been predicted from the patient’s hearing thresholds in the majority.
Presence of ipsilateral acoustic reflex artifact may result in clinical misidentification
Published in International Journal of Audiology, 2022
Dorothy Neave-DiToro, Michael Bergen, Shlomo Silman, Michele B. Emmer
The acoustic reflex is a bilateral reflex that occurs within the middle ear due to the presentation of high intensity acoustic stimulation. The exact physiological function and the evolution of the reflex is still debated within the literature and numerous theories exist (McGregor et al. 2018). This reflex can be stimulated and measured in the same ear (ipsilateral testing) or can be measured in one ear while the stimulating tone is presented to the opposite ear (contralateral testing). Acoustic reflex testing is being used globally to aid in the detection of middle ear pathologies such as middle ear effusion, otosclerosis, and ossicular discontinuity (Silman and Silverman 1991; Hunter and Shahnaz 2013; Silman and Emmer 1995). Reflex testing has been used to aid in the prediction of hearing loss (Emmer and Silman 2003; Flamme et al. 2017), differential diagnosis of auditory neuropathy (Berlin et al. 2005; Emanuel, Henson, and Knapp 2012; Schairer, Feeney, and Sanford 2013; Flamme et al. 2017), non-organic hearing loss and those at risk for retrocochlear impairment such acoustic neuromas and cerebellopontine angle tumours by use of normative 90th percentile data (Silman and Gelfand 1981). Furthermore, the ipsilateral acoustic reflex threshold (IART) is found to be an important tool in the detection of facial nerve pathology (Silman et al. 1988). More recently, the use of ARTs to assess binaural summation (Rawool and Parrill (2018) and to aid in the diagnosis of noise-induced cochlear synaptopathy (Guest et al. 2019) has been discussed.
Evaluation of auditory disability and cochlear functions in industrial workers exposed to occupational noise
Published in Hearing, Balance and Communication, 2021
The audiometric assessment was preceded by anamnesis, otoscopy and 24 hour acoustic rest from the occupational noise. Pure tone audiometry was performed to all subjects with audiometry (AC 40, DK-500; Interacoustics, Middelfart, Denmark) in an acoustic booth. TDH 39 supra-aural headphones were used to perform pure tone audiometry test. Air conduction hearing thresholds at 250, 500, 1000, 2000, 4000, 6000 and 8000 Hz and bone conduction hearing thresholds at 500, 1000, 2000 and 4000 Hz were evaluated also speech discrimination and speech recognition tests were performed to all subjects. The hearing was considered normal if hearing thresholds at 250, 500, 1000, 2000, 4000, 6000 and 8000 Hz were less than 20 dB HL. Tympanometric measurements were performed to all subjects with impedance audiometer (AZ 26; Interacoustics; Middelfart, Denmark) and ipsilateral–contralateral acoustic reflex measurements were performed at 500, 1000, 2000 and 4000 Hz. Subjects with type A tympanogram (static compliance of 0.3–2.0 cc and peak pressures of –100 to +50 daPa) and normal ipsilateral and contralateral acoustic reflexes thresholds (80–100 dB HL) at 500, 1000, 2000 and 4000 Hz included in this study [17].
Peripheral and central auditory function in adults with epilepsy and treated with carbamazepine
Published in Hearing, Balance and Communication, 2019
Sherifa A. Hamed, Amira M. Oseily
In this study, more than one third of the patients had abnormalities in acoustic reflex (but normal tympanometry) and mild deficits in PTA and abnormalities in BAEPs indicating delayed auditory conduction within the peripheral pathways and brainstem. The acoustic reflex (stapedius) is an involuntary muscle contraction that occurs in the middle ear in response to high-intensity sound stimuli. The reflex decreases the transmission of vibrational energy to the cochlea, where it is converted into electrical impulses to be processed by the brain. The acoustic reflex normally occurs only at relatively high intensities; activation for quieter sounds can indicate ear dysfunction. The pathway involved in the acoustic reflex is complex and can involve the ossicular chain (malleus, incus and stapes), the cochlea (organ of Corti), the auditory nerve, brainstem, facial nerve and other components [44]. In the presence of normal tympanometry, the abnormal acoustic reflex might be attributed to abnormalities in auditory nerve or its pathway within the brainstem. The auditory abnormalities in BAEPs were obvious particularly at high repetition rate frequencies (milliseconds) of BAEPs than with low repetition rate frequencies [45–47]. The increased drug concentrations, dose and/or prolonged exposure to CBZ were found to be associated risks of auditory pathway dysfunction [48–51].