Posted: January 12, 2014
The measurement of both auditory brainstem response (ABR) and cochlear microphonic (CM) response is important in the assessment of hearing disorders. ABR represents the status of the neural components primarily at the brainstem level in the auditory system, while CM response represents the status of the cochlea (inner ear) arising from the sensory hair cells which convert sound into neural activities. In some disorders, the two types of responses are not correlated, meaning that one cannot be used to predict the other. For instance, in auditory neuropathy disorder the disappearance of ABR does not necessarily indicate that the condition of the cochlea is abnormal.
Traditionally, electrodes have been placed at the mastoid and ear canal to measure ABR and CM responses respectively. However, this traditional approach requires two distinct electrodes, which adds to the cost of the procedure. As well, the placement of the ear canal electrode requires additional training and a cooperative subject. Dr. Ming Zhang at the University of Alberta and the Glenrose Rehabilitation Hospital has designed a new electrode called the concha electrode, which can record ABR and CM responses simultaneously using a simple design that is both user-friendly and economical. The concha electrode has successfully been tested in healthy subjects which showed that the CM response measured was not significantly different from those measured separately with the ear canal electrode, and additionally the ABR was clearly evident. Furthermore, fewer postauricular artifacts were observed by the concha electrode than the mastoid electrode, providing more precise measurements. Moreover, the CM response can be used to assess cochlear low-frequency function (e.g., at 500 Hz, an important frequency in the pure-tone-average test), which is difficult to assess using otoacoustic emission (OAE) tests in the clinic.
- The concha electrode can assess both cochlear and neural conditions simultaneously with fewer postauricular artifacts than mastoid electrode, which provides a more efficient diagnostic process;
- Cochlear low-frequency function (e.g., at 500 Hz) can be assessed, which is difficult using OAE tests in the clinic.
- User-friendly electrode design does not require a high degree of training;
- Placement of the electrode outside the ear canal enhances patient comfort, reduces the requirement of patient cooperation, and decreases accidental bruising of the canal due to cough induced by canal-cleaning in newborns.
- Ease of use and comfort reduces the impact on patients and make it especially ideal for the pediatric population, for example, during newborn hearing screening;
- The device does not require a gold foil as required by canal electrode, and it is also durable and reusable as well as then more cost-efficient. Remote clinics may have concerns with the availability and cost of a canal electrode. This device would be of interest to companies in the auditory diagnostic industry.
This device would be of interest to companies in the auditory diagnostic industry.