Cochlear Implant Fitting in Child: Sweep and SHCHUP

Special Article - Cochlear Implant

Austin J Otolaryngol. 2016; 3(4): 1084.

Cochlear Implant Fitting in Child: Sweep and SHCHUP

Petrov SM* and Gritsjuk MI

Research Institute of the Ear, Throat, Nose, and Speech, St. Petersburg, Russia

*Corresponding author: Petrov SM, Research Institute of the Ear, Throat, Nose and Speech, St. Petersburg, Russia

Received: September 29, 2016; Accepted: November 30, 2016; Published: December 02, 2016

Abstract

Routine technique of stapedial reflex registration on electric stimulation is applied for cochlear implant fitting of small children. The problem is long duration of this procedure. In order “to shrink” time of reflexometry we suggest method of consecutive stimulation of all 12 electrodes of implant with simultaneous registration of stapedial reflexes – SWEEP method (patented). Threshold levels of stapedial reflex are used as Most Comfortable Levels (MCLs). But these levels are not the best ones for cochlear implanted patients.

Since CI-patients hear sounds, we have to use sounds for fitting too. So we propose our method of fitting by sound stimuli. We divided spectrum of white noise in accordance with widths of every channel, equalized Sound Pressure Level (SPL) of all these bands and summed bands of 1-4, 5-8, 9-12 channels. Patient establishes most comfortable SPL of these stepped noises. In accordance with results of investigation we regulates electrical MCL in appropriate channels (patented). Our method SHCHUP is successfully used for cochlear implant fitting of small children after ESRT-fitting.

Keywords: Cochlear implantation; Fitting; Stapedial reflex; Sweep stimulation-registration; Stepped noise; Most comfortable SPL; Threshold of discomfort

Abbreviations

CI: Cochlear Implanted; MCL: Most Comfortable Level; SPL: Sound Pressure Level

Case Presentation

The basis for successful rehabilitation of implanted patient is optimal fitting of speech processor, i.e. precise setting of threshold and most comfortable levels for each channel. Implant fitting of small children represents the difficult task since they cannot reliably estimate loudness of single electrical stimuli.

In these cases routine technique of stapedial reflex registration on electric stimulation is applied. Threshold levels of stapedial reflex are used as MCLs.

Definition of reflex threshold levels is performed independently for each of 12 channels. It is too long procedure for small child. Not every child will agree to pass the whole procedure in one examination.

In order “to shrink” time of reflexometry we use our method.

Practical use of SWEEP-method

Impedance meter AA220 is set into DECAY mode; program Maestro is set into DINAMIC SWEEP-stimulation mode. Amplitude of stimuli – MCLs in program under research.

Research is performed as follows: a child is in setup mode, probe of impedancemeter is entered in the contralateral ear and the impedancemeter is ready for work. Duration of electrical impulses is 300ms, interval between them equals to 600ms. With this parameters of stimuli we are able to stimulate consecutively all 12 channels of implant OPUS-2 and to register (or do not to register) reflexes during one session of Decay mode scan. Simultaneously “Decay” mode on the impedancemeter and “Sweep” program on PC in Maestro are executed. On display of the impedancemeter we see/don’t see 12 stapedial reflexes.

If threshold reflexes in some channels are discovered we do not change the stimulus level in these channels. In those channels, where clear reflex was discovered, we decrease levels of stimulation. In others, where reflex was absent, we increase levels and conduct new session of SWEEP stimulation-registration. This procedure is repeated until threshold levels of reflex will be registered in all channels.

As example of the procedure, the results of research for one examinee are presented in following pictures. Pictures 1-3 were printed from screen of impedancemeter and then were scanned (Figure 1).