09-12, 14:00–15:00 (Europe/Istanbul), Audiology 2
The types of signals used in Auditory Brainstem Responses (ABR) can be examined in three groups: Click stimuli that include all frequency bands, Tone-Burst stimuli that include a narrow frequency band, and Chirp stimuli.
Chirp stimuli were developed to compensate for the cochlear wave delay problem when click stimuli are used in ABR. Chirp stimuli have a wide-band (like click stimuli CE-Chirp) form as well as narrow-band stimuli (like tone-burst stimuli Narrow Band CE-Chirp).
The Chirp stimulus was developed by Claus Elberling (2007) to compensate for the wave delay in the cochlea. Due to the specially adjusted temporal distribution of its components, CE Chirp stimulus simultaneously accesses characteristic regions of the basal membrane. Since all cochlear regions are simultaneously depolarized by the CE-Chirp stimulus, ABR waves with higher amplitude are obtained (1).
To eliminate the cochlear wave delay problem that occurs when a tone burst stimulus is used, the NB CE-Chirp stimulus (2). In addition, the Level Specific (LS) CE-Chirp stimulus type has been developed by creating different delay models according to the intensity level at which the developed CE-Chirp stimulus is sent.
Studies on CE-Chirp ABR: Khorsand Sabet et al. (2014) found CE-Chirp ABR wave V amplitudes to be larger than Click ABR in individuals with normal hearing (3). Stuart et al. (2014) reported that larger wave V amplitudes were obtained with the CE-Chirp stimulus at 30 dB nHL than with the Click stimulus in newborns (4).
Ferm et al (2013) found 1 and 4 kHz NB Chirp ABR thresholds to be approximately 5 dB better than tone pip ABR thresholds in infants undergoing newborn screening (5). Cargnelutti et al. (2017) found that in people with normal hearing, wave V amplitudes were larger with LS CE-Chirp ABR than with click ABR at 85 dB nHL (6).
This information in the literature shows that ABR performed with Chirp stimulus types can be used effectively to estimate behavioral hearing thresholds.
References
1. Elberling C. Auditory brainstem responses to a chirp stimulus designed from derived-band latencies in normal hearing subject. J. Acoustical Society of America November 2008;124 (5): 3022
2. Rodriques GR, Ramos N, Lewis DR. Comparing auditory brainstem responses (ABRs) to toneburst and narrow band CE-Chirp in young infants. Int J Pediatr Otorhinolaryngol. 2013 Sep;77(9):1555-60
3. Khorsand Sabet V, Mandavi-Zafarghandi ME, Safavi M, Sharifian M, Tabatabaee SM. Comparison of click and CE Chirp-evoked human auditory brainstem responses: a preliminary study. Aud 2014;23(4):69-76
4. A Stuart; Cobb, Kensi M. Effect of stimulus and number sweeps on the neonate auditory brainstem response. Ear and Hearing The Official Journal of the American Society 2014;35(5):585-588
5. Ferml L, Lightfoot G, Stevens J. Comparison of ABR response amplitude, test time, and estimation of hearing threshold using frequency-specific chirp and tone pip stimuli in newborns. Int J Audiol 2013; 52(6):419-423
6. Cargnelutti M, Cóser PL, Biaggio EPV. LS CE-Chirp® vs. Click in the neuroaudiological diagnosis by ABR. Braz J Otorhinolaryngol., 2017,Jun;83(3):313-317.
The aim was to evaluate whether the Chirp stimulus types that have come into clinical use in recent years are effective in estimating behavioral hearing thresholds.
Superior semicircular canal dehiscence (SSCD) is a conductive pathology of inner ear origin. Otosclerosis is a metabolic disease of the otic capsule and results in progressive stapes fixation in the oval window.
The low-frequency conductive hearing loss observed in SSCD is similar to the audiologic features seen in otosclerosis. Therefore, differential diagnosis between otosclerosis and SSCD is important. There is an opening in the bony region at the apex of the superior semicircular canal. Vestibular dysfunction and auditory symptoms occur together (1).
In the differential diagnosis, while acoustic hearing reflexes are affected in otosclerosis, they are observed to be present in SSCD. The Vestibular evoked myogenic potentials (VEMPs) are important in the differential diagnosis of SSCD and otosclerosis. VEMPs are a neurophysiological assessment technique used to evaluate the vestibular functions of patients. VEMPs are classified as ocular VEMPs (oVEMPs) and cervical VEMPs (cVEMPs) based on the recording sites. In recent years, the use of the cVEMP test in auditory-vestibular evaluation has become increasingly widespread (2). While VEMP responses are obtained in conductive hearing pathologies originating from the inner ear, VEMP responses may not be obtained in conductive hearing pathologies originating from the middle ear. Therefore, VEMP responses cannot be obtained in otosclerosis, whereas VEMP thresholds may be determined to be lower than they should be in SSCD and enlarged vestibular aqueduct syndrome. Halmagyi et al. (3) reported that cVEMP responses could not be obtained when the air-bone gap was greater than 20 dB in pure tone audiometry. Bath et al. (4) reported that 97% of patients with conductive hearing loss did not have a cVEMP response.