Prospective Benefits of Deep Electrode Insertion For Children With Cochlear Implants

Claude Jolly, Joachim Mueller

The advantage of deep electrode insertion for adults with cochlear implants has been demonstrated in several studies (Büchner et al 2004, Hochmair et al 2003, Boeheim et al 2002). Benefits include extended pitch domain, reduced channel interaction due to greater channel separation from base to apex, and better performance in noise with the apical electrode activated. Measures of benefit have been established by focusing on the contribution of the apical region to performance in noisy and quiet environments. Without the apical electrode switched on, patients performed poorer in clinical testing. Experience will adult users suggest that young and very young children will also benefit from apical stimulation of the cochlea. Additional benefits for children may be related to the neural activation of central processes initiated by peripheral electrical stimulation. It has been demonstrated that stimulation of the auditory nerve through a cochlear implant within the critical time window of auditory development (age 0-4) initiates fastest functional maturation of the auditory cortex (Sharma et al, 2005).

An electrode array providing apical stimulation is able to stimulate the region of the auditory cortex dedicated to low frequencies, that might otherwise be taken over by middle or high frequencies. A deeply inserted electrode could therefore provide a better starting point for cortical development in prelingually deaf children.


 

	MED-EL deep insertion electrodes allow all maximum number of neural elements to be stimulated (cells, dendrites, axons). X-ray microsocopy by Prof. Hüttenbrink.
	Spiral ganglion neurons (green) in the basal turn are arranged in clusters.
	The spiral canal (Rosenthal’s Canal in the basal to middle turn) in the apex ends in a bulge.

PHOTOS:
Anneliese Schrott-Fischer and Rudolf Glueckert
Medical University Innsbruck, Austria
annelies.schrott@uibk.ac.at
Helge Rask-Andersen
Uppsala University Hospital, Sweden
helge.rask-andersen@akademiska.se

ELECTRON MICROSCOPY:
Kristian Pfaller
Division of Embryology and Histology
Medical University of Innsbruck, Austria
Kristian.pfaller@i-med.ac.at