Auditorische Synaptopathie/Neuropathie

Abstract

Auditory synaptopathy/neuropathy (AS/AN) is a special subtype of sensorineural hearing disorders with heterogeneous phenotypes and underestimated incidence. AS/AN generally develops in infancy, occasionally in adulthood. Symptoms include fluctuating, mostly bilateral hearing loss and abnormally reduced speech comprehension, especially in noisy environments. Within audiological assessments, patients with AS/AN present otoacoustic emissions (TEOAE; DPOAE) and cochlear microphonics (CM), absence of stapedius reflexes (SR) as well as absent or pathologically altered auditory evoked brainstem potentials (ABR). Children with AS/AN cannot be identified within OAE-based newborn hearing screening programs. Clinical findings, transtympanic electrocochleography (ECoG) and further diagnostic tools permit further identification of individual characteristics. In individual cases conventional amplification and the use of FM systems may improve hearing and communication skills. If these interventions, accompanied by intensive hearing, speech and language therapy are unsuccessful, cochlear implants (CI) or alternative forms of communication may be useful options for rehabilitation.

Investigation of Maximum Monosyllabic Word Recognition as a Predictor of Speech Understanding with Cochlear Implant

“…The objective clarification of these cases appears difficult, as findings that can be clearly interpreted, e.g., via electrocochleography, seem to show a lower incidence with increasing age [28]. Deprivational processes within the auditory periphery offer a possible explanation [29]. Reduced top-down functions, such as impaired linguistic and neurocognitive abilities, should also be considered as a possible cause [30].…”

Aktuelle audiologische Diagnostik

“…Nachweisbar ist diese Suppression durch Messung der Click-evozierten TEOAE bei Beschallung des anderen Ohres mit einem breitbandigen Rauschen, dessen Pegel im Bereich von 50 bis 70 dB HL liegt. Im Falle einer Auditorischen Synaptopathie/Neuropathie (AS/AN) ist der Suppres sionseffekt geringer oder er bleibt ganz aus [162,206,207]. Für den Nachweis dieses Effektes sollte die Reizsequenz so gewählt werden, dass die linearen Anteile der Reizantwort nicht eliminiert werden ("linear mode").…”

“…Mit der Möglichkeit zur zuverlässigen frequenzspezifischen Objektivierung der Schwelle im Kindesalter leistet die ECochG etwas, wozu keine der anderen Methoden in der Lage ist. Über die Schwellenbestimmung hinaus trägt die ECochG zur Diagnostik der AS/AN bei; die charakteristische Befundkonstellation besteht darin, dass nur das CM, aber kein SAP nachweisbar ist [162,206,207,248,249].…”

Current audiological diagnostics

“…This suppression can be identified by measurement of the click-evoked TEOAE when providing sound to the other ear with a broadband noise that has a level of 50–70 dB HL. In cases of auditory synaptopathy/neuropathy (AS/AN), the suppression effect is lower or completely missing [ 162 ], [ 206 ], [ 207 ]. In order to prove this effect, the "nonlinear" stimulus sequence, which eliminates the linear components of the response, should not be selected (“linear mode”).…”

“…Regarding the frequency-specific objectification of the threshold in children, ECochG is more powerful than most other methods. Beyond the determination of threshold, ECochG contributes to the diagnostics of AS/AN; the characteristic finding is the constellation of clearly pronounced CMs and depleted or lacking CAPs [ 162 ], [ 206 ], [ 207 ], [ 248 ], [ 249 ].…”